WorldWideScience

Sample records for bearing piles

  1. Grouted Pile and Its Bearing Capacity

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The grouting method applied in bored pile is an improvement to the conventional bored pile. Load tests have proved that grouting under the bored pile tip is an effective method to enhance the bearing capacity of the pile and to reduce the pile settlement. In this paper, the grouting technology is described and pile-load test results are discussed. In order to put the grouting method into design practice, the authors analyze the working mechanism of soil compaction. And, based on the theory of cavities expansion in soil mass, approximate formulae are proposed for estimating the bearing capacity of the grouted pile. The theoretical prediction agrees well with the load test results.

  2. Bearing Behaviors of Stiffened Deep Cement Mixed Pile

    Institute of Scientific and Technical Information of China (English)

    WU Mai; ZHAO Xin

    2006-01-01

    A series of investigations were conducted to study the bearing capacity and load transfer mechanism of stiffened deep cement mixed (SDCM) pile.Laboratory tests including six specimens were conducted to investigate the frictional resistance between the concrete core and the cementsoil.Two model piles and twenty-four full-scale piles were tested to examine the bearing behavior of single pile.Laboratory and model tests results indicate that the cohesive strength is large enough to ensure the interaction between core pile and the outer cement-soil.The full-scale test results show that the SDCM piles exhibit similar bearing behavior to bored and cast-in-place concrete piles.In general, with the rational composite structure the SDCM piles can transmit the applied load effectively, and due to the addition of the stiffer core, the SDCM piles possess high bearing capacity.Based on the findings of these experimental investigations and theoretical analysis, a practical design method is developed to predict the vertical bearing capacity of SDCM pile.

  3. Bearing capacity and mechanical behavior of CFG pile composite foundation

    Institute of Scientific and Technical Information of China (English)

    陈秋南; 赵明华; 周国华; 张主华

    2008-01-01

    CFG pile (i.e., pile constructed by granular materials of cement, fly-ash and gravel) composite foundation is applied in subsoil treatment widely and successfully. In order to have a further study of this kind of subsoil treatment technology, the influencing factors and calculation methods of the vertical bearing capacity of single CFG pile and the CFG pile composite foundation were discussed respectively. And based on the obtained solutions, effects by the cushion and measurements to reduce negative friction area were analyzed. Moreover, the developing law of settlement and bearing capacity eigenvalue controlled by the material strength with the increase of load were given for the CFG composite foundation. The in-situ static load test was tested for CFG pile. The results of test show that the maximum test load or half of the ultimate load is used from all the points of test, the average bearing capacity eigenvalue of single pile is 390 kN, and slightly greater than the design value of bearing capacity. The bearing capacity eigenvalues of composite foundation for 3 piles are greater than 300 kPa, and the mechanical properties of CFG pile composite foundation are almost identical in the case of the same load and cushion thickness. The pile-soil stress ratio and the load-sharing ratio can be adjusted through setting up cushion thickness.

  4. Vertical bearing capacity of pile based on load transfer model

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-hua; YANG Ming-hui; ZOU Xin-jun

    2005-01-01

    The load transfer analytical method is applied to study the bearing mechanism of piles with vertical load in this paper. According to the different hardening rules of soil or rock around the pile shaft, such as work-softening, ideal elasto-plastic and work-hardening, a universal tri-linear load transfer model is suggested for the development of side and tip resistance by various types of soil (rock) with the consideration of sediment at the bottom of the pile. Based on the model, a formula is derived for the relationship between the settlement and load on the pile top to determine the vertical bearing capacity, taking into account such factors as the characteristics of the stratum, the side resistance along the shaft, and tip resistance under the pile tip. A close agreement of the calculated results with the measured data from a field test pile lends confidence to the future application of the present approach in engineering practice.

  5. The Influence of Time on Bearing Capacity of Driven Piles

    DEFF Research Database (Denmark)

    Jensen, J. Lysebjerg; Augustesen, A.; Sørensen, Carsten S.

    2004-01-01

    In Danish engineering practice, one of the ways to determine the ultimate bearing capacity of an axially loaded pile is by means of geostatic formulas. In the equation describing the contribution from the shaft friction to the total bearing capacity for piles located entirely or partly in clay......, a regeneration factor appears. The regeneration factor accounts for effects of dissipation of pore pressure due to pile driving and true time effects such as ageing on the ultimate bearing capacity. Normally the factor is 0.4 but in this paper, the influence of the undrained shear strength and time...

  6. Bearing Capacity of Mixed Pile with Stiffness Core

    Institute of Scientific and Technical Information of China (English)

    YUE Jianwei; JIANG Xinliang; LING Guangrong

    2006-01-01

    To study load transfer mechanism and bearing capacity of a mixed pile with stiffness core (MPSC), which is formed by inserting a precast reinforced concrete pile (PRCP), in-situ tests involving MPSCs with different lengths, diameters, water cement ratios and PRCPs, cement mixed piles, and drilling hole piles, were carried out.Limit bearing capacities, load-settlement curves and stress distribution of MPSCs and mixed piles were obtained.The load transfer between cement soil and PRCP was analyzed by finite element method (FEM).Test results and FEM analysis show that an MPSC has fully utilized the big friction from a cement mixed pile and the high compressive strength from a PRCP which transfers outer top load into the inner cement soil, and that inserting a PRCP into a mixed pile changes the stress distribution of a mixed pile and improves frictional resistance between a mixed pile and soil.The length and the section area on PRCP of an MPSC both have an optimum value.Adopting MPSC is effective in improving the bearing capacity of soft soil ground.

  7. Experimental Study on Post Grouting Bearing Capacity of Large Diameter Bored Piles

    Directory of Open Access Journals (Sweden)

    Wang Duanduan

    2015-01-01

    Full Text Available Post grouting can improve the inherent defects such as the formation of the mud cake at pile side and the sediment at pile end in the process of bored pile construction. Thus post grouting has been widely used in Engineering. The purpose of this paper is to research the influences of post grouting to pile bearing capacity more systematically and intuitively. Combined with the static load test of four test piles in Weihe River Bridge test area of new airport highway in Xi’an, the bearing capacity and settlement of routine piles and post grouting piles are comparatively analyzed. The test results show that under the same geological condition, post grouting can improve the properties of pile tip and pile shaft soil of bored piles significantly, enhance the ultimate resistance, improve the ultimate bearing capacity and reduce the pile tip settlement. Then post grouting can aim to optimize pile foundation.

  8. Mechanism Research on the Improvement of Bearing Capacity of Single Pile by Pile-base Post Grouting Technique and Estimation of Bearing Capacity

    Directory of Open Access Journals (Sweden)

    Zhao Feng

    2015-01-01

    Full Text Available The slurry wall bored grouting has some defects. The pile-base post grouting technique can efficiently make up these defects and greatly improve the bearing capacity. Based on the pile-base post grouting technique and its process analysis, this paper carries out a detailed analysis about the improvement of mechanism of bearing capacity and mechanism of spherical expansion by the use of pile-base post grouting technique, as well as the estimation method of the bearing capacity of pile-base post grouting pile, which has a certain reference value for theoretical research and technical application of the technique.

  9. Mechanism Research on the Improvement of Bearing Capacity of Single Pile by Pile-base Post Grouting Technique and Estimation of Bearing Capacity

    OpenAIRE

    Zhao Feng

    2015-01-01

    The slurry wall bored grouting has some defects. The pile-base post grouting technique can efficiently make up these defects and greatly improve the bearing capacity. Based on the pile-base post grouting technique and its process analysis, this paper carries out a detailed analysis about the improvement of mechanism of bearing capacity and mechanism of spherical expansion by the use of pile-base post grouting technique, as well as the estimation method of the bearing capacity of pile-base pos...

  10. Dynamic load testing on the bearing capacity of prestressed tubular concrete piles in soft ground

    Science.gov (United States)

    Yu, Chuang; Liu, Songyu

    2008-11-01

    Dynamic load testing (DLT) is a high strain test method for assessing pile performance. The shaft capacity of a driven PTC (prestressed tubular concrete) pile in marine soft ground will vary with time after installation. The DLT method has been successfully transferred to the testing of prestressed pipe piles in marine soft clay of Lianyungang area in China. DLT is investigated to determine the ultimate bearing capacity of single pile at different period after pile installation. The ultimate bearing capacity of single pile was founded to increase more than 70% during the inventing 3 months, which demonstrate the time effect of rigid pile bearing capacity in marine soft ground. Furthermore, the skin friction and axial force along the pile shaft are presented as well, which present the load transfer mechanism of pipe pile in soft clay. It shows the economy and efficiency of DLT method compared to static load testing method.

  11. Bearing Capacity Estimation of Bridge Piles Using the Impulse Transient Response Method

    Directory of Open Access Journals (Sweden)

    Meng Ma

    2016-01-01

    Full Text Available A bearing capacity estimation method for bridge piles was developed. In this method, the pulse echo test was used to select the intact piles; the dynamic stiffness was obtained by the impulse transient response test. A total of 680 bridge piles were tested, and their capacities were estimated. Finally, core drilling analysis was used to check the reliability of this method. The results show that, for intact piles, an obvious positive correlation exits between the dynamic stiffness and bearing capacity of the piles. The core drilling analysis proved that the estimation method was reliable.

  12. Experimental Study on Post Grouting Bearing Capacity of Large Diameter Bored Piles

    OpenAIRE

    Wang Duanduan; Wang Longfei; Zhang Lipeng

    2015-01-01

    Post grouting can improve the inherent defects such as the formation of the mud cake at pile side and the sediment at pile end in the process of bored pile construction. Thus post grouting has been widely used in Engineering. The purpose of this paper is to research the influences of post grouting to pile bearing capacity more systematically and intuitively. Combined with the static load test of four test piles in Weihe River Bridge test area of new airport highway in Xi’an, the bearing capac...

  13. Reliability Analysis of Bearing Capacity of Large-Diameter Piles under Osterberg Test

    Directory of Open Access Journals (Sweden)

    Lei Nie

    2013-05-01

    Full Text Available This study gives the reliability analysis of bearing capacity of large-diameter piles under osterberg test. The limit state equation of dimensionless random variables is utilized in the reliability analysis of vertical bearing capacity of large-diameter piles based on Osterberg loading tests. And the reliability index and the resistance partial coefficient under the current specifications are calculated using calibration method. The results show: the reliable index of large-diameter piles is correlated with the load effect ratio and is smaller than the ordinary piles; resistance partial coefficient of 1.53 is proper in design of large-diameter piles.

  14. Regressive approach for predicting bearing capacity of bored piles from cone penetration test data

    Directory of Open Access Journals (Sweden)

    Iyad S. Alkroosh

    2015-10-01

    Full Text Available In this study, the least square support vector machine (LSSVM algorithm was applied to predicting the bearing capacity of bored piles embedded in sand and mixed soils. Pile geometry and cone penetration test (CPT results were used as input variables for prediction of pile bearing capacity. The data used were collected from the existing literature and consisted of 50 case records. The application of LSSVM was carried out by dividing the data into three sets: a training set for learning the problem and obtaining a relationship between input variables and pile bearing capacity, and testing and validation sets for evaluation of the predictive and generalization ability of the obtained relationship. The predictions of pile bearing capacity by LSSVM were evaluated by comparing with experimental data and with those by traditional CPT-based methods and the gene expression programming (GEP model. It was found that the LSSVM performs well with coefficient of determination, mean, and standard deviation equivalent to 0.99, 1.03, and 0.08, respectively, for the testing set, and 1, 1.04, and 0.11, respectively, for the validation set. The low values of the calculated mean squared error and mean absolute error indicated that the LSSVM was accurate in predicting the pile bearing capacity. The results of comparison also showed that the proposed algorithm predicted the pile bearing capacity more accurately than the traditional methods including the GEP model.

  15. Analytical Model for the End-Bearing Capacity of Tapered Piles Using Cavity Expansion Theory

    Directory of Open Access Journals (Sweden)

    Suman Manandhar

    2012-01-01

    Full Text Available On the basis of evidence from model tests on increasing the end-bearing behavior of tapered piles at the load-settlement curve, this paper proposes an analytical spherical cavity expansion theory to evaluate the end-bearing capacity. The angle of tapering is inserted in the proposed model to evaluate the end-bearing capacity. The test results of the proposed model in different types of sands and different relative densities show good effects compared to conventional straight piles. The end-bearing capacity increases with increases in the tapering angle. The paper then propounds a model for prototypes and real-type pile tests which predicts and validates to evaluate the end-bearing capacity.

  16. Study on Load-Bearing Characteristics of a New Pile Group Foundation for an Offshore Wind Turbine

    Directory of Open Access Journals (Sweden)

    Ruiqing Lang

    2014-01-01

    Full Text Available Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.

  17. Study on load-bearing characteristics of a new pile group foundation for an offshore wind turbine.

    Science.gov (United States)

    Lang, Ruiqing; Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect. PMID:25250375

  18. Study on load-bearing characteristics of a new pile group foundation for an offshore wind turbine.

    Science.gov (United States)

    Lang, Ruiqing; Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.

  19. Numerical simulation of the influence of soil core on the bearing capacity of pipe pile

    Directory of Open Access Journals (Sweden)

    G.Ya. Bulatov

    2010-03-01

    Full Text Available The cost of the foundation can be up to 20-30% of the total building cost. Reducing consumption of materials and quality selection of the required characteristics of the pile can reduce both the estimated cost and time of work.In terms of compact construction and the high land prices the most relevant is high-rise building. But it is hard to build in soft ground conditions (for example, in St. Petersburg. The situation is complicated by insufficiently explored methods of selection and design of piles (especially steel-tube piles for specific cases of construction, as well as by the absence of regulatory documents related to the high-performance technology.The article considers the clarification methods for calculating the bearing capacity of tubular steel piles. An additional contribution of soil core to the overall bearing capacity due to accounting an effect of its "natural" selflocking in the cavity of the steel pipe is considered.The conclusions about the effectiveness of the piles, depending on different initial parameters are made.

  20. Application of pressuremeter measurements for the prediction of bearing capacity of verticaly loaded piles

    OpenAIRE

    Robas, Alenka

    2007-01-01

    Pressuremeter is an in situ test widely in operation in France, and in the last decade it has won recognition all over the world, as well as in Slovenia. Basically it is used to determinate the soil characteristics needed for the design of foundations. This thesis deals with the calculation of the bearing capacity of the vertically loaded piles using different methods based on pressuremeter measurements. The thesis deals only with buildings on deep foundations and because the u...

  1. CFG桩复合地基承载力分析%Analysis of bearing capability of CFG pile composite foundation

    Institute of Scientific and Technical Information of China (English)

    贾剑青; 王宏图; 李晶; 张宪; 范晓刚

    2011-01-01

    The CFG pile is used to consolidate the foundation in one passenger dedicated line.The field experiments including low strain dynamic testing,bearing capability of single pile and the composite foundation are done,and the bearing capability of composite foundation is calculated,too.The results show that the first and second class piles account for 93.9% and 6.1% respectively,and the bearing capability eigenvalues of single pile and composite foundation are larger than the designed values.The 3D FEM model is established to simulate the stresses of CFG pile top and inter-pile soil changing with load level,and the stress ratio between CFG pile and inter-pile soil is analyzed,too.The following results are got from the calculation results of FEM: 1) the stresses of CFG pile top and inter-pile soil increase with load level,but the increasing rate of the former is larger than the latter;2) the stress ratio between CFG pile and inter-pile soil increases quickly when the load level is low,and it tends to convergent gradually with load increasing.%某客运专线某标段采用CFG桩加固技术。对CFG桩进行了低应变动测、单桩承载力试验、复合地基承载力试验及理论计算。结果表明:一类桩占93.9%,二类桩占6.1%;单桩承载力及复合地基承载力特征值均大于设计值。建立了三维有限元模型,模拟分析了CFG桩顶及桩间土应力随加载水平的变化关系以及CFG桩及桩间土应力分担比。模拟结果表明:1)随着荷载的增加,CFG桩顶应力及桩间土应力也随之增大,但CFG桩顶应力的增长速率大于桩间土;2)加载初期,CFG桩与桩间土应力分担比逐渐增大,且增长速度较快;随着荷载的增加,桩土应力分担逐渐趋于稳定。

  2. Dynamic torsional response of pre-strained end bearing pile embedded in pre-strained isotropic saturated soil medium

    Institute of Scientific and Technical Information of China (English)

    胡文韬; 夏唐代; 张智卿

    2013-01-01

    The influence of initial strain state on the dynamic response of an end bearing pile embedded in isotropic saturated soil is investigated through the linearized theory of small elastic perturbation superposed on largely stressed bodies. The governing equations for soil, based on Biot’s poroelasticity theory, are derived in the cylindrical coordinates, and the pile is modeled by using the one-dimensional elastic theory. The analytical solutions of pile impedance, frequency response of both twist angle and time history of velocity response are obtained by using of separation of variables technique. Finally, a parametric study of the influence of initial strains on the torsional impedance, twist angle, and velocity response at the top of the pile is carried out.

  3. Experimental study on load bearing behavior of large-scaled caps with pile groups

    Institute of Scientific and Technical Information of China (English)

    Guo Chao; Lu Bo; Gong Weiming; Qiu Hongxing

    2009-01-01

    The objective of this investigation was to study the behavior of deep pile caps and the ultimate load-carrying capacity. Four 1/10 scaled models of nine-pile caps were cast and tested on vertical loads to failure. The destruction shapes of pile caps, the correlation between load and displacement, and the internal stresses were analyzed systematical-ly. The results demonstrated that the failures of all the four models are resulted from punching shear; the internal flow of the forces in nine-pile caps can be approximated by "strut-and-fie" model. Furthermore, the failure loads of these spec-imens were predicted by some of the present design methods and the calculated results were compared with the experi-mental loads. The comparative results also indicated that the "strut-and-tie" model is a more reasonable design method for deep pile caps design.

  4. 浅析挤扩多盘桩单桩竖向抗拔承载力%ANALYSISON THE PUSH-EXTEND MULTI-UNDER-REAMED PILE BEARING CAPACITY OF SINGLE PILE PULLED ON VERTICAL LOADS

    Institute of Scientific and Technical Information of China (English)

    任佳佳; 钱永梅; 尹新生

    2012-01-01

    通过研究挤扩多盘桩的现有抗拔承载力计算方法,提出利用传统模式来计算挤扩多盘桩的抗拔承载力的不足之处,并根据挤扩多盘桩在竖向拔力作用下的土体的破坏特征和桩的受力机理,提出最新的挤扩多盘桩抗拔承载力的计算模式,为该型桩的设计应用提供可靠的理论依据。%By studying the existing calculation method of pulled out of the bearing capacity of the push-extend multi-under- reamed pile, this article put forward deficiencies of the traditional mode to calculate the bearing capacity of the push-extend multi-under-reamed pile, and according to the push-extend multi-under-reamed pile under vertical pull force the characteristics of the soil destruction and working mechanism of pile, put forward the newest calculation method of pulled out of the bearing capacity of the push-extend multi-under-reamed pile, the reliable theory basis will influence the application of the expansion multiple disk pile.

  5. 滚压成型灌注螺纹桩承载性能研究%Bearing Capacity Behavior of Roll Forming Filling Screw Pile

    Institute of Scientific and Technical Information of China (English)

    徐学燕; 于琳琳; 刘复孝

    2011-01-01

    采用静载荷试验及数值计算相结合的方法进行了螺纹桩承载性能的研究.分析了螺齿宽度、螺距等桩型参数对螺纹桩承载性能的影响,对外径相同的直径桩与螺纹桩的承载性能进行了静载荷对比试验研究.螺纹桩单桩极限承载力较相同桩外径的直型桩极限承载力稍高,螺齿宽度对螺纹桩的极限承载力影响非常明显,随螺齿宽度的增加螺纹桩的极限承载力增大;螺距对极限承载力影响也较为明显,随螺距的减小,螺纹桩的极限承载力增大.螺纹桩在低荷载水平下,桩侧阻力沿桩身均匀发挥,桩端阻力较小,随荷载水平的增大,桩端阻力大幅提高,并提出螺纹桩承载力的计算公式.%Bearing capacity behavior of roll forming filling screw pile (screw pile for short) is investigated through numerical calculation and static load test. The influence of pile-type parameters, such as width of thread tooth and thread pitch, on the ultimate bearing capacity of crew pile is studied; furthermore, the bearing capacity behavior of screw pile and that of pile with the same diameter are compared and analyzed through static load test. The results show that the ultimate bearing capacity of screw pile is a bit higher than that of pile with the same outside diameter; width of thread tooth has a distinct effect on ultimate bearing capacity which increases with the increment of width of thread tooth. When the screw pile is tested under light load, the resistance on pile side is distributed along screw pile, and tip resistance is small, but the resistance rises considerably with load increasing. Besides, the design formula of bearing capacity of screw pile is proposed.

  6. 爆炸荷载下桩基竖向动承载力研究%Study on vertical bearing capacity of pile foundation under blast loading

    Institute of Scientific and Technical Information of China (English)

    王后裕; 姚焕忠; 言志信; 张剑寒; 杨进勇

    2013-01-01

    针对地面抗爆工程建设中桩基设计问题,采用动三轴试验、动力有限元方法等手段,开展了爆炸作用下地基土的动力特性及桩基抗爆承载力研究,结果表明桩基竖向极限抗爆承载力为其竖向极限静承载力2倍以上,高于按照现行桩基规范得到的1.25 ~1.5倍范围值,表明将常规抗震设计的办法直接用于抗爆炸冲击荷载的桩基设计时偏保守.%For the problem of pile foundation design of ground protective projects subjected to blast loading,a series of resrearches of dynamic property of soil and bearing capacity of pile under shock waves are carried out by the methods of dynamic triaxial test and dynamic FEM and so on.The result shows that the dynamic bearing capacity of pile is two times greater than that of static bearing capacity and 1.25 ~ 1.5 times greater than that of current pile code method.Therefore it is conservative to estimate the dynamic bearing capacity of pile with current pile code method.

  7. 轮胎桩复合地基承载性能研究%Numerical Simulation Research on Bearing Capacity of Rubber Tire Pile Composite Foundation

    Institute of Scientific and Technical Information of China (English)

    王凤池; 高寰; 张明; 董明

    2015-01-01

    In order to improve the utilization of waste tires and the bearing capacity of the composite foundation ,a new type of composite foundation with rubber tire piles was put forward .Based on the laboratory test data ,the bearing capaci-ty of tire pile composite foundation ,stress distribution of soil in the pile and lateral deformation of the pile were analyzed using the simulation software FLAC3D .The results indicate that the better the mechanical properties of the soil around the pile ,the larger the bearing capacity of the tire pile composite foundation .When there is a great difference between the compressive modulus of the soil around the pile and in the pile ,the depth gradually increases with the load .Its effect of foundation reinforcement is better than that of granular material piles .%为提高废弃轮胎的利用率,提高复合地基的承载能力,提出了一种新型复合地基,即轮胎桩复合地基。以室内试验数据为基础,利用 FLAC3D数值模拟软件对承载能力、桩内土体应力分布进行了模拟分析。结果表明:桩周土体的力学性质越好,轮胎桩复合地基的承载力越大。当桩周土体的压缩模量与桩内土体的压缩模量相差较大时,随着荷载的增加影响深度逐渐增大。其加固地基的效果较散体材料桩要好。

  8. 潮汕车站桩网复合地基管桩承载性状数值分析%Numerical Analysis on Bearing Behavior of the Piles in Pile-net Composite Foundation for Chaoshan Railway Station

    Institute of Scientific and Technical Information of China (English)

    姚志勇

    2012-01-01

    采用桩网复合地基,对软土地基进行加固处理是十分有效的措施。依托厦深铁路潮汕车站深厚软土的地基处理,利用FLAC3D有限元计算软件对潮汕车站桩网复合地基管桩承载性状进行数值模拟分析,以研究管桩桩身轴力特性及管桩桩身摩阻力分布特性。负摩阻力对桩网复合地基有不利的影响,其增大了桩的沉降量,降低了桩对上部荷载承载能力和桩网复合地基的整体工作性能。在工程设计过程中应充分考虑负摩阻力对桩承载力及沉降的影响。%It is a very effective measure that using the pile-net composite foundation to reinforce the soft foundation.In this paper,based on the foundation treatment of deep soft soil in the Chaoshan railway station area on Xiamen-Shenzhen Railway,the bearing behavior of pile of the pile-net composite foundation is analyzed by using the numerical simulation software FLAC3D to study the distributing properties of axis force and skin friction of pile body.The negative skin friction affect the pile-net composite foundation adversely because it can increase the settlement of pile and reduce upper bearing capacity of pile and whole working performance of pile-net composite foundation.During the engineering design process,the influence of negative friction on pile bearing capacity and settlement should be taken into full account.

  9. Experimental study concerning lift bearing value of wide bottom and caison type pile foundation for transmission pylon

    Energy Technology Data Exchange (ETDEWEB)

    Okuyama, Kazuo; Tanino, Kengo; Sugiyama, Futami

    1988-07-30

    The transmission route becomes mountain area because many power sources become distant, so that the foundations must be mainly made by manpower. Therefore, the caison type pile foundation is used in many cases and further the scale becomes larger. The wide bottom foundation, where the base bottom is enlarged, is applied to construct economically. It is known that the lift bearing value is increased by enlarging the width but it is necessary to confirm whether the existing calculation technique can be applied or not, so that large field tests and model experimenta in a centrifugal force field were conducted. The lift bearing value is increased with the increase of penetration but the fracture type changes from the logarithmic spiral to the withdrawal type and when the surface inclines, the foundation inclines to valley side even if the lift load is vertical. Moreover, if the foundation width is smaller, the ground over the enlarged width is compressed, resulting fracture of the withdrawal type but if the width is too large, the fracture type changes to the logarithmic spiral type and the bearing value becomes larger. It is necessary to select ground which is uncompressible or has positive dilatancy. (30 figs, 10 tabs, 3 refs)

  10. Bearing Behaviors of Rubberized Cement-Soil Pile Composite Foundation%橡胶水泥土桩复合地基的承载性状

    Institute of Scientific and Technical Information of China (English)

    王凤池; 史富民; 徐云龙; 刘凤起

    2011-01-01

    通过橡胶水泥土桩复合地基室内载荷试验,研究了橡胶水泥土桩复合地基的承载特性及橡胶粉掺量的影响.对于橡胶水泥土单桩复合地基,桩土荷载随上部荷载变化存在再分配过程.桩土应力比在加载过程中非定值,曲线呈上单凸峰变化.褥垫层厚度对橡胶水泥土单桩复合地基的桩土应力比同样有调节作用.随着橡胶粉掺量的增加,复合地基的比例界限值增加;桩身的应变增大并沿随桩身高度呈显著线性变化;桩土应力比值减小.研究表明,合理调整桩身橡胶粉掺量可以优化桩土应力比,改善复合地基承载性能.%Through indoor load tests on rubberized cement-soil pile composite foundation, its bearing behavior and the influences of rubber powder content were studied. For the rubberized cement-soil pile composite foundation, the bearing load of pile and soil is redistributed when the upper load changes. The value of pile-soil stress ratio is not definite in the loading process and the shape of pile-soil stress ratio curve has single upper leptokurtosis. The thickness of cushion also has regulating effect on pile-soil stress ratio. With the rubber powder content increasing, the ratio limit value of composite foundation increases; the strain along pile body height increases linearly significantly and the pile-soil stress ratio decreases. The results show that reasonable adjustment of rubber powder content can optimize the pile-soil stress ratio and improve the bearing capacity of composite foundation.

  11. Relationship between pile foundation bearing capacity and its dynamic stiffness%桩基承载力与其动刚度的关系

    Institute of Scientific and Technical Information of China (English)

    刘建磊; 马蒙; 张勇; 缴玉森

    2015-01-01

    为分析桩基承载力与机械阻抗法中动刚度的关系,在同一场地设计了4根相同尺寸的带有不同程度缺陷的模型桩(缩颈桩或断桩),对模型桩进行了机械阻抗法动测和静载试验。建立了桩—土有限元模型,利用模型桩测试数据对有限元模型进行校准,并分析了完整桩在冲击动荷载和静载试验中对主要物理参数的敏感性;同时分析了缩颈、扩颈缺陷对桩基动刚度的影响规律。研究结果表明:对于相同形式、相近地层环境中的桩基,动刚度能很好地反映静力特性;动刚度对影响桩基承载能力的缺陷较为敏感,合理动刚度下限值可以作为桩基承载力的预警值。%In order to investigate the relationship between the bearing capacity of pile foundation and its dynamic stiffness in the impulse transient response method ( T RM ) ,four model piles,with same size but different damage ( necking or breaking) ,were designed in a same test field. Dynamic response was measured with T RM and static load test was performed. A pile-soil finite element model was built,calibrated by model pile tests. Sensitivity of main parameters were analyzed for intact piles under impulse and static loads,and the effect of necking or expanding defects on dynamic stiffness were studied. It revealed that dynamic stiffness reflected the corresponding static characteristics for pile foundations with the same type and located in similar ground environment. Dynamic stiffness is sensitive to the defects which affect the pile bearing capacity,and a reasonable lower bound of dynamic stiffness can be used as a precaution for pile bearing capacity.

  12. Numerical simulation of bearing capacity of the bored pile in soft rock%软岩钻孔灌注桩承载力的数值模拟

    Institute of Scientific and Technical Information of China (English)

    高长岭; 李荣峰; 柴建峰

    2012-01-01

    如何确定软岩地区钻孔灌注桩的承载力是一个复杂而又亟待解决的问题.本文以南京长江三桥软岩钻孔灌注桩为例,利用数值模拟法(FLAC3D模拟分析),模拟南京长江三桥软岩钻孔灌注桩逐级加载后的受力性状,根据得到的桩周土岩的应力场、位移场及破坏区的分布和扩展,确定软岩钻孔灌注桩的极限承载力.将数值模拟结果和自平衡测试结果进行比较,笔者发现两者吻合较好.%A method for determining the bearing capacity of bored piles in soft rock areas has been a complex problem that should be solved urgently. Taking the bored piles in soft rock of the third bridge over the Yangtze River in Nanjing as an example and using the numerical simulation method (FLAC3D simulation analysis), this paper simulated the force behavior of the bored piles in soft rock of the third bridge over the Yangtze River in Nanjing in the case of step stress test. Based on stress field, displacement field and the distribution and expansion of the failure zone obtained in the soil and rock around the pile, the authors determined the ultimate bearing capacity of the bored pile in soft rock. A comparison with the numerical simulation results and the self-balanced load test results shows that the numerical simulation result agrees well with the self-balanced load test result.

  13. 非饱和土中端承桩水平振动特性研究%Horizontal vibration of an end-bearing pile in unsaturated soil

    Institute of Scientific and Technical Information of China (English)

    章敏; 王星华; 冯国瑞

    2015-01-01

    针对非饱和土中桩的水平稳态振动问题,采用三相多孔介质波动方程,考虑固、液、气三相材料间的惯性和黏性耦合效应以及基质吸力的影响,通过Helmholtz矢量分解及分离变量法解耦波动方程,并将基桩等效为能描述其剪切变形和转动惯性效应的铁摩辛柯(Timoshenko)梁模型,采用Novak三维连续介质模型对非饱和土中端承桩的稳态水平振动进行了理论推导,获得了桩顶水平频域响应解析解,讨论了饱和度对土层和桩顶阻抗的影响以及桩身位移、内力沿深度的分布规律。结果表明,随着土体饱和度的升高,土层复阻抗和桩顶动力阻抗增大,桩身位移和内力则相应地减小;饱和度,包括渗透系数在内的影响仅在土体接近准饱和时才得以发挥;频率较低时,短桩拥有较大的刚度因子。桩长越长,阻抗因子越大,而共振频率越低。当长径比超过10时,桩顶阻抗不再随长径比的增加而改变。%Up to now horizontal vibration response of a single pile in unsaturated soil is analyzed theoretically. The unsaturated soil surrounding pile is described by three-phase poro-elastic theory, which takes into account the viscous and inertial coupling between solid skeleton and pore fluids as well as the matrix suction, while the pile embedded in unsaturated soil is end bearing and treated as a Timoshenko beam model to describe the shear deformation and rotational inertia effects. The Helmholtz decomposition and variable separation method are firstly adopted to decouple the governing equations of the unsaturated soil. And then a rigorous mathematical formulation of the pile-head frequency–response function is deduced by virtue of the three-dimensional continuum model proposed by Novak and the compatibility between the pile and soil. The influences of degree of saturation on the impedances of pile and soil together with the distribution of

  14. Pressured Grouting Method (PGM) in Pile Engineering

    Institute of Scientific and Technical Information of China (English)

    吴兴序; 于志强; 王旭

    2002-01-01

    Application of pressured grouting method (PGM) in pile engineering can tackle problems encountered during construction of bored piles. Bearing capacity of piles can be increased through compaction of subsoils around piles. This paper reports research efforts of this technique by the pile research team in Southwest Jiaotong University in last decade with respect to the construction process, test findings, and primary research conclusions. The social-economical benefits of this method and application market in pile engineering are also analyzed.

  15. Comparison of Design Bearing Capacity and Site Static Load Test of the Cast-in-place Piles in Caohe Aqueduct%漕河渡槽灌注桩承载力与静载试验比较

    Institute of Scientific and Technical Information of China (English)

    杨胜慧

    2013-01-01

    The cast-in-place piles foundation is adopted in the Caohe aqueduct body. There is 0.5 meter of the piles foun-dation entering into the weak weathered rock, the bearing capacity of the piles foundation is calculated according to point bearing pile . The static load test is adopted to check the the bearing capacity of the cast-in-place pile foundation, the test results show that the bearing capacity of pile foundation in Caohe aqueduct meet the design requirements.%漕河渡槽槽身段采用灌注桩基础,桩基进入弱风化岩石0.5m,按纯端承桩计算桩基承载力。采用桩基静载试验检测桩基承载力,试验结果表明,漕河渡槽桩基承载力达到设计要求。

  16. Calculation of axially bearing capacity of a batter pile based on mechanism of deformation compatibility%基于变形协调的斜桩轴向承载力计算方法

    Institute of Scientific and Technical Information of China (English)

    张麒蛰; 卓卫东; 范立础

    2013-01-01

    In order to obtain the axial bearing capacity of a batter pile , the calculation formula for the axially bearing capacity of a batter pile was deduced based on the non-uniform distribution char-acteristics of the friction resistance around the batter pile shaft and the mechanism of pile -soil deformation compatibility .The results calculated by the proposed formula and the method given by the design code of pile were compared to explore the influence of the factors , such as pile inclina-tion, diameter, length and utmost friction resistance around pile shaft , on axial bearing capacity. The calculated results showed that the value of the pile axially bearing capacity calculated by the proposed formula decreased with the increase of pile inclination .For different pile diameters , the pile axially bearing capacity was 7%smaller than that calculated by the code's formula.The shorter of the pile length or the lesser of the utmost friction resistance of the pile was , the smaller bearing capacity calculated by the code's formula was than the values calculated by the proposed formula . Finally , with the increase of the pile length or utmost friction resistance , the value of bearing capaci-ty calculated by this proposed formula was greater than the value calculated by the code's formula. The proposed formula also takes into account of the influence of pile inclination and the mechanism of pile-soil deformation compatibility .It can be a reference to calculate axial bearing capacity of bat-ter piles.%为进一步研究斜桩轴向承载力计算方法,基于斜桩的桩周摩阻力不均匀分布的特性和桩-土受力变形协调的原则,推导了斜桩轴向承载力计算公式,通过对比本文公式与规范公式的计算结果,揭示了桩身倾角、桩径、桩长和桩侧极限摩阻力等因素对斜桩轴向容许承载力的影响规律。结果表明:鉴于规范公式未考虑斜桩桩身倾角对承载力的影响,本文公式计算得

  17. 预应力管桩承载力抗拔系数试验分析%Test and Analysis of Prestressed Pipe Pile Bearing Capacity Pull-out Coefficient

    Institute of Scientific and Technical Information of China (English)

    陈捷; 周同和; 王会龙

    2015-01-01

    通过两组8台现场静载荷试验的成果分析和已有试验成果的比较,研究了采用静压和锤击施工的预应力管桩(采用PHC)在黏土与粉土中的承载力抗拔系数。结果表明,受到桩端阻力与桩侧阻力相互作用的影响,桩端位于承载力较高的砂层时,预应力管桩承载力抗拔系数较小,桩端位于桩端阻力较小的黏土层时,预应力管桩承载力抗拔系数较大。土层抗拔系数受长径比影响较大,长径比大的桩,上部土层抗拔系数可能较大;长径比较小时,下部土层抗拔系数可能较大。研究成果可供建筑抗浮工程优化设计作为参考。%By the analysis of two groups of eight field static load test results and the comparison of existing test results,we studied the bearing capacity uplift coefficient of PHC Piles whose construction adopts hydrostatic pressure and hammering in clay and silt. The results show that bearing capacity of pile resistance coefficient is little when the bearing capacity of pile tip into the higher sand layer,the bearing capacity of pile resistance coefficient is larger when we put the pile end into the clay layer of smaller pile side resistance due to the influence of pile end resistance of pile side resistance. The aspect ratio has a great influence on the bearing capacity uplift coefficient of soil layer. When the aspect ratio is larger,the bearing capacity uplift coefficient of soil upper layer is greater than the pile of little aspect ratio;the bearing capacity uplift coefficient of soil lower layer may be greater than the upper soil layer when the pile has small aspect ratio;The research results can be used for reference by the building anti-floating engineering optimization design.

  18. Grouting for Pile Foundation Improvement

    OpenAIRE

    Van der Stoel, A.E.C.

    2001-01-01

    The aim of this research was to examine the use of grouting methods for pile foundation improvement, a generic term that is used here to define both foundation renovation (increasing the bearing capacity of a pile foundation that has insufficient bearing capacity) and foundation protection (safeguarding the piles of the foundation against possible damage resulting from underground construction activities in the vicinity). A full-scale test, of which the general set-up and consistency check ar...

  19. 轴向荷载对斜桩水平承载特性影响试验及理论研究%Test and theoretical research on influence of axial load on lateral bearing capacity of batter piles

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      斜群桩受水平荷载作用时,群桩中的基桩受到径向荷载、轴向荷载和弯矩的共同作用。为研究轴向荷载对斜桩水平承载特性的影响,完成了3根单桩以及1组1×2斜桩的大尺寸模型试验。试验结果表明:轴向拉力作用会降低斜桩的水平刚度和极限承载力;而轴向压力作用则会使其水平刚度和极限承载力提高。基于桩侧浅层土体楔形破坏假定,推导了考虑轴向荷载影响的斜桩水平极限土抗力计算公式,提出了桩侧土抗力的p-y曲线方法,并通过模型试验及现场试验验证其合理性。%When batter pile group are under lateral load, the foundation piles in pile group are subjected to radial load, axial load and bending moment. In order to study the influence of axial load on lateral bearing capacity of batter piles, large-scale model tests of three single piles and a 1×2 batter pile group have been conducted in a larger soil tank. It is found that the upward axial force on the pile top decreases the lateral stiffness and the lateral ultimate bearing capacity of batter pile; while the downward axial force enhances the horizontal stiffness and the lateral ultimate bearing capacity of batter pile. Based on the assumption of wedge failure of the shallow soil around piles, considering the influence of axial load on piles, a formula for calculating the lateral ultimate resistance force of soil is deduced. Then, a p-y curve method for resistance force of soil around piles is proposed. Finally, the formula and the proposed p-y curve method for batter pile are verified by model tests and field tests.

  20. 灰土挤密复合地基桩体极限承载力统一解%Unified solution of ultimate bearing capacity of piles in lime-soil composite foundation

    Institute of Scientific and Technical Information of China (English)

    赵均海; 崔莹; 张常光; 孙珊珊

    2013-01-01

    As the values of theoretical calculation for ultimate bearing capacity of piles are quite different from the actual measured values, with the unified strength theory and considering the compatibility condition between piles and soil, the theoretical calculation formula for ultimate bearing capacity of piles has been put forward involving the following factors such as regarding the soil around single pile reinforced area as a long thick-walled cylinder and considering the lateral ultimate binding pressure which soil can exert on pile. Furthermore, the influence factors such as intermediate principal stress, the length of pile and the internal friction angle of lime-soil pile are illustrated according with an actual project and the values calculated by the formula are in good accordance with the actual measured values of ultimate bearing capacity of piles. The results show that the intermediate principal stress has great impact on the lateral ultimate binding pressure which soil can exert on piles. The solution with consideration of the intermediate principal stress has the positive effect on the ultimate strength of soil. And the value of ultimate bearing capacity of piles increases with the increase of the length of piles or with the increase of the internal friction angle of lime-soil.%针对目前灰土挤密复合地基桩体极限承载力理论计算值与实测标准值存在较大差异的问题,将单桩加固区的土体视为一定深度的长厚壁圆筒,基于统一强度理论和桩土变形协调条件,推导了桩孔极限内压下的灰土桩极限承载力统一解.讨论中间主应力、桩长和内摩擦角对灰土桩极限承载力的影响特性,并将理论公式计算值与实测标准值进行了对比,吻合较好.研究结果表明:中间主应力对土体所能提供的侧向极限约束力有较大影响;考虑中间主应力影响对岩土材料的强度发挥有着积极作用;增加桩长和灰土的内摩擦角,灰土桩极限承载力相应提高.

  1. 大直径扩底人工挖孔桩承载力研究%Experimental Research on Bearing Capacity of Large-Diameter Belled Pile

    Institute of Scientific and Technical Information of China (English)

    杨砚宗

    2014-01-01

    Based on a practical project in Wuhan, the bearing capacity of large-diameter belled pile has been studied by the limits of rock uniaxial compressive strength and deep plate loading test to determine the carrying capacity value of the bearing layer. We used standardized formulas to evaluate by two sets of test parameters characteristic values of pile capacity, and used static load tests to validate the estimated carrying capacity. The results showed that:the estimated carrying capacity of deep plate loading test, which is significantly greater than the uniaxial compressive strength test, is very similar with static load test. The plate loading test can accurately estimate the single pile loading capability, and that can provide a reliable reference for the design of large-diameter belled pile.%依托武汉某工程实例,对大直径扩底人工挖孔桩承载力进行了研究,通过岩石极限单轴抗压强度室内试验和深层载荷板试验确定持力层的承载力特征值,采用规范提供的计算公式,用两套试验参数对单桩承载力进行预估,并通过现场单桩载荷试验对计算结果进行验证。研究表明:深层载荷板试验参数预估单桩承载力特征值,明显大于岩石极限单轴抗压强度室内试验计算值,且前者与单桩静载荷试验结果更为接近,可准确预估单桩承载力,进而为后续大直径扩底挖孔桩设计提供可靠参考。

  2. Research On Bearing Capacity Of Micropile Groups Arranged Inclined Piles By Numerical Simulation%斜桩布置对微型桩群桩承载力影响的数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    吴开辉

    2015-01-01

    采用plaxis有限元软件,对三组设置斜桩的微型桩群桩进行数值计算分析,分析结果显示,布置斜桩时,群桩的抗压、抗拔以及水平承载力相比于未设置斜桩情况均有一定程度的提高,进一步分析,斜桩的设置对2×2群桩的提高效果最为显著,3×3群桩次之,4×4群桩最小,本文的数值分析结果具有一定的工程应用价值。%The finite element software “plaxis” is adopted to calculate and analyze the establishment of three micro -pile groups with the inclined pile .The analysis showed that the ability of compressive resistance , anti-pulling and lateral bearing capacity has improved a lot than those without inclined pile .After further analysis , the settlement of the inclined pile has the most remarkable effect for 2 ×2 pile groups , the 3 ×3 pile groups second , and the 4 ×4 pile groups is minimum .The result of the numerical calculation analysis has great value in engineering field .

  3. 大直径钻孔灌注桩的竖向承载性能%Vertical bearing capacity of large-diameter bored pile

    Institute of Scientific and Technical Information of China (English)

    刘念武; 龚晓南; 俞峰

    2015-01-01

    T he self‐balancing test w as conducted on tw o 2 .2 m diameter drilled piles in order to analyze the bearing capacity of large diameter bored piles .The test results were compared with in‐situ test results . Results show that the change of load‐displacement of pile with post‐grouting is slower than pile without post‐grouting .The end resistance reached the limit state when pile tip displacements approached 20 mm (1% D ,D is the pile diameter) .The side resistance increased firstly and maintained a stable trend with the increase of pile‐soil relative displacement .The critical displacement was 1 .5‐3 .0 mm .Post‐grouting can improve the side resistance over a certain depth from the pile tip ,and the improvement in round gravel mixed pebble bed is 18 percent . Resistive loads up and dow n the side of the load cell is different and transformation coefficient is 0 .92 and 0 .91 , respectively . Side resistance and undrained vane‐shear strength has a linear relationship and has a better goodness of fit .The ultimate side resistance of round gravel mixed can be estimated by dynamic sounding (63 .5 kg) hits .%为了分析大直径钻孔灌注桩的承载性能,对2根直径分别为2.2m的钻孔灌注桩开展自平衡试验,将试验结果与原位测试结果进行对比分析.通过对测试结果的分析发现,注浆后荷载箱的向上及向下荷载‐位移曲线的变化更加缓慢,当桩端位移为20 mm(1% D ,其中 D为桩径)左右时,端阻达到极限状态,未注浆桩和注浆桩的极限端阻分别为2834、3561 kPa .桩身侧阻随着桩土相对位移的增大呈先增大后保持稳定的趋势,淤泥质粉土层、黏土夹粉砂层、圆砾混卵石层的侧阻在桩土相对位移为1.5~3.0mm时达到稳定.注浆能够提高桩端以上一定深度的桩身侧阻,圆砾混卵石层中侧阻的提高幅度约为18%.荷载箱上下的侧阻随位移的变化模式不同,未注浆桩

  4. Bearing capacity and load transfer mechanism of static drill rooted nodular piles%静钻根植竹节桩承载力及荷载传递机制研究

    Institute of Scientific and Technical Information of China (English)

    周佳锦; 王奎华; 龚晓南; 张日红; 严天龙; 许远荣

    2014-01-01

    The static drill rooted nodular pile is a new type of composite pile foundation which consists of precast nodular pile and the cemented soil along the pile shaft. This kind of composite pile has a good bearing capacity, and the mud pollution will largely be reduced in its construction process. A group of experiments were conducted to provide a comparison between this composite pile and the bored pile. The axial force of the nodular pile was measured by the strain gauges attached on the pile shaft to analyze the distribution of the axial force and the skin friction along the shaft; and then a three-dimensional model was built by using the ABAQUS finite element program to investigate the load transfer mechanism of this composite pile in detail. The results of the field tests and ABAQUS simulation showed that:the bearing capacity of the static drill rooted nodular pile is better than that of the bored pile in soft soil area. The settlement of the composite pile is controlled by the precast pile, and the deformation of the precast pile and the cemented soil can be considered as deformation compatibility. The nodes on the nodular pile play an important role during the load transfer process;and the skin friction of the static drill rooted nodular pile is about 1.05-1.10 times of the skin friction of the bored pile in the same soil layer.%静钻根植竹节桩是由预应力竹节桩和桩周水泥土构成的一种新型组合桩基,该新型桩不仅承载性能较好,而且可以大量减少桩基施工过程中所产生的泥浆污染。通过静钻根植竹节桩和钻孔灌注桩的静荷载对比试验及埋设在竹节桩桩身上的应变计对桩身轴力进行测量,分析了静钻根植竹节桩桩身的轴力分布情况以及侧摩阻力的分布,用有限元软件ABAQUS对静钻根植竹节桩进行三维建模计算,详细地分析这种新型组合桩的荷载传递机制。结合现场试验与模拟计算可以得到:在软土地区,静

  5. Numerical analysis of bearing characteristics of composite subgrade reinforced by chemical churning pile groups%旋喷群桩复合地基承载特性的数值分析

    Institute of Scientific and Technical Information of China (English)

    安关峰; 张洪彬; 刘添俊

    2012-01-01

    旋喷桩加固软土地基在各种地基处理工程中得到了广泛应用.对旋喷桩的研究多数集中在其施工工艺的改进上,或者针对单桩的承载特性进行研究,而对旋喷群桩的承载特性则研究不多.根据工程实际情况,采用基于MIDAS-GTS的三维有限元分析技术,通过改变旋喷群桩的布置方式、桩弹性模量、桩长、桩径、桩距等设计参数及桩-土接触面等参数对旋喷群桩复合地基承载特性的影响进行了研究.研究表明:旋喷桩加固软土地基主要减小了地表至桩底深度范围内土体的竖向沉降,对桩底下方的土体沉降基本无影响;提高旋喷桩桩径及材料强度会提高复合地基承载能力;不同旋喷桩布置方式、桩-土之间是否设置Goodman接触面单元对地基承载能力基本无影响.%The method of soft soil subgrade reinforcement with chemical churning pile is used more and more in projects of subgrade treatment. At present, the researches about chemical churning pile usually focus on improvement in construction techniques or bearing characteristics of single pile. But research about bearing characteristics of chemical churning pile groups is not much. Based on MIDAS-GTS three-dimensional finite element analysis, the influence of design parameters on bearing characteristics of chemical churning pile groups is studied. These design parameters of chemical churning pile include layout, elastic modulus, length, diameter of piles, and distance between piles, the parameters of interface between piles and soil. The results show that the vertical settlement of soil within the range between surface and pile bottom is reduced in soft soil subgrade reinforced by chemical churning piles; but the method has little effect on the vertical settlement of soil under pile bottom. Larger pile diameter and higher material strength can improve the bearing capacity of composite subgrade. But different layouts of chemical churning piles

  6. 非埋式桩板结构路基承载机制%Bearing capacity mechanism of non-embedded pile-plank structure subgrade

    Institute of Scientific and Technical Information of China (English)

    苏谦; 王武斌; 白皓; 廖超; 赵伟

    2012-01-01

    Sensor components were disposed at the typical section of test subgrade, and the bearing capacity mechanism of non-embedded pile-plank structure in deep collapsible loess foundations was studied by long-term observation. The pile-soil interaction was considered, the concept of comprehensive rotation stiffness was introduced based on the principle of equal stiffness, the vertical and horizontal plane models of the subgrade were installed, and the deformation and mechanical characteristic of the structure were analyzed. Measured result shows that the test value of structural main reinforcement stress agree well with the theoretical calculation value, the difference is about 10%-30~//00, and the maximum reinforcement stress of 60. 60 MPa appears at the cross section of joist. Pile side earth bears about 95% of total load, and no negative friction is produced. The load transfer law of the structure is different from that of traditional subgrade, load can be transferred to deeper bearing layer by pile foundation, which improves the stress state of soft soil section. Half a year, after the laying completion of track construction, the largest accumulated settlement of top surface for bearing plank occurs at the cross section of mid-span, which is 1.0 mm, and meets the requirement of settlement control. 1 tab, 12 figs, 15 refs.%为了研究深厚湿陷性黄土地基非埋式桩板结构路基的承载机制,选取试验段典型断面进行元器件布置与长期观测;考虑桩土相互作用,依据等刚度的原则引入综合转动刚度的概念,建立了纵、横向平面分析模型,对非埋式桩板结构的受力与变形特性进行测试分析。实测结果表明:结构主筋应力测试值与理论值相差10%~30%,吻合较好,最大值出现在托梁支座断面上侧,为60.60MPa;桩侧土体承受约95%的荷载,且未产生负摩阻力;桩板结构的荷载传递规律与传统路基不同,桩基将荷载传递到更

  7. 厚层沉渣嵌岩桩承载性状研究%Research on bearing behavior of rock-socketed piles in thick sediments

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    In situ core-drilling tests and static loading tests are carried out on rock-socketed pile. The test results show that when using the impact pore-forming construction and the upper part is a weakly cemented soil, pile bottom sediment thickness is generally larger, which is much thicker than the specified value by the foundation code. When the load reached a certain value, sudden and large subsidence is observed, because the end resistance does not take effect due to the existence of a thick layer of sediments. The test results indicate that the current design method of rock-socketed pile which considering both of the end and side resistance is not appropriate when impact pore-forming construction is used and there is weakly cemented soil around the pile. The bearing capacity of single rock-socketed pile should be determined by side resistance in soil and the socketed segment in rock. Numerical analysis is carried out on the distribution of side resistance of the rock-socketed segment and deformation and load carrying capacity of the pile. Under a given applied load, smaller settlement is observed when socketed thickness and rock strength is greater. With the increase of the applied load on pile top, settlement difference caused by the variation of socketed thickness and rock strength increases. The distribution of side resistance of the socketed segment along the vertical direction shows a double-peak saddle shape. When the socketed thickness and rock strength are smaller, the lower peak is higher than the upper peak. When the socketed thickness and rock strength are larger, the lower peak is lower than the upper peak. Under a given applied load on the pile top, smaller socketed thickness would result in larger settlement and side resistance. Due to the thick layer of sediment, the axial force of the rock-socketed segment of the pile gradually decreases from the applied load on pile top to zero along vertical direction, the smaller the socketed thichness, the

  8. 基于MTA的浅部缺陷端承桩的频谱特性分析%Spectral response of shallow defect end-bearing piles based on modal test and analysis

    Institute of Scientific and Technical Information of China (English)

    卢明; 王齐仁

    2012-01-01

    Low strain reflected wave method was widely used in the pile foundation quality evaluation . In order to overcome the limitations of analysis of shallow defect end - bearing piles rely on the characteristics of the elastic wave . From the angle of the vibration test and analysis, the modal testing theory ( MTA) was introducted, the frequency domain response theory model was built, that of various shallow End - bearing piles, the characteristics and laws of modal response were analysised in the piles head motivate, the theoretical basis was provided that of piles testing and defect judgment.%低应变反射波法已广泛应用于桩基质量评价,为了克服单纯依靠弹性波渡动学特性来分析浅层缺陷端承桩的局限,从振动测试与分析的角度,引入模态试验分析理论(MTA),建立了浅部各种缺陷端承桩的频率域响应理论模型,分析了浅部各种缺陷端承桩在桩头激励下的模态响应特征和规律,为工程桩检测和缺陷判断提供理论依据.

  9. 天津厚地层超长钻孔灌注桩单桩承载特性研究%Research on vertical bearing capacity of single super-long bored pile in thick stratum of Tianjin

    Institute of Scientific and Technical Information of China (English)

    柯洪; 吴翔; 王继华; 曾云川; 赵春宏; 冯庆高

    2011-01-01

    The layers of a main tower construction site in Tianjin are mainly clay, silt and silt sand. Two groups of the super-long bored test piles with post pressure-grouting (a total of eight piles) are designed to take bearing behavior test using single pile vertical static load test of compression to master the engineering properties in the main tower construction site. Vibrating wire reinforcement meter and stratified settlement tube are installed to find out the pile side friction and the pile body layered settlement state. After the test, the results of the data analysis show that the pile side grouting can significantly improve the long pile side skin friction; pre-load pressure can enhance the flexibility of the super-long pile and reduce the settlement of the top of the pile in some degree. After unloaded stability, the test pile also has side resistance; the resistance of the upper segment is negative skin friction; and the lower segment is positive skin friction; and the pile body axial force causes the test pile to have some compression volume; that is an important part of the residual deformation.%天津市某主塔楼桩基选用后压浆超长钻孔灌注桩,为了掌握超长后压浆钻孔灌注桩在该地层的工程特性,共设计了2组(共8根)试桩进行单桩竖向抗压静载试验.试桩中安装了振弦式钢筋计和分层沉降管以反映桩侧摩阻力和桩身分层沉降状态.对试验数据进行对比分析和计算结果表明,桩侧注浆可以明显提高超长桩的侧摩阻力;采用预压加载可以增强超长桩的弹性,减少桩项的沉降;卸荷稳定后试桩具有桩侧阻力,桩身上段所受阻力为负摩阻力,下段为正摩阻力,同时具有的桩身轴力使试桩产生一定的压缩,其压缩量为残余变形量的重要组成部分.

  10. ANALYSIS ON THE DETERMINAION OF VERTICAL LOAD-BEARING CAPACITY OF SINGLE PILE WITH NEW AND OLD REGULATIONS%浅析新、旧规范单桩竖向承载力的确定

    Institute of Scientific and Technical Information of China (English)

    姬立君; 李爱群; 赵恩山

    2001-01-01

    通过桩基础新、旧规范对比的论述,指出了在以静压法确定单桩承载力时,旧规范存在着的不足及新规范具有的优点。%By comparison with new and old regulations of pile foundation, the paper points out faults of old regulations and advantages of new regulations when static pressure method is used to determine load-bearing capacity of single pile.

  11. 时间对复合地基桩间土承载力的影响研究%Study about influence of time on bearing capacity of soil between piles in composite foundation

    Institute of Scientific and Technical Information of China (English)

    张军平; 刘涛; 吴宗璋

    2013-01-01

      结合青藏铁路西格段增建二线工程碎石桩复合地基工程实例,通过重型动力触探试验和桩间土承载力计算分析,研究了复合地基桩间土承载力随软土固结时间提高的特性,得到了动力触探曲线随时间变化的规律;理论分析了地基处理后瞬时桩间土承载力与处理前地基承载力的关系,得到了时间对桩间土承载力影响的规律,给碎石桩复合地基的处理效果提供评价依据,为碎石桩复合地基上层的路基施工提供科学指导。%In accordance to the project of gravel pile composite foundation in the double tracking project in Xining-Golmud section of Qinghai-Tibet Railway,and computational analyses of heavy dynamic penetration test and the bearing capacity of soil between piles,this paper studies the time characteristics of bearing capacity of soil between piles in composite foundation increasing with the soft soil consolidation,and gets the regulation that dynamic penetration curves change with time and the feature that soil between piles increases with time as well. Besides,in theory,this paper elaborates on the relation between momentary bearing capacities of soil between piles after and before soil foundation process,and gets influence mechanism of time on bearing capacity of soil between piles. At last,this study provides the evaluation basis for the processing treatment of gravel pile composite foundation and scientific guidance for roadbed construction of the upper layer of gravel pile composite foundation.

  12. Grouted jetted precast concrete sheet piles: Method, experiments, and applications

    OpenAIRE

    Xu, GH; Yue, ZQ; Liu, DF; He, FR

    2006-01-01

    This paper introduces an innovative technology - grouted jetted precast concrete piling - that increases the efficiency of piling operations in coastal regions. The technology includes the following steps: (i) casting concrete piles factory-designed especially for jetting and grouting; (ii) jetting to drive the concrete piles with a crane on a floating ship or platform into soil; and (iii) grouting to enhance the sheet pile connections and to increase the pile bearing capacity. This technolog...

  13. Big Pile or Small Pile?

    Science.gov (United States)

    Branca, Mario; Quidacciolu, Rossana G.; Soletta, Isabella

    2013-01-01

    The construction of a voltaic pile (battery) is a simple laboratory activity that commemorates the invention of this important device and is of great help in teaching physics. The voltaic pile is often seen as a scientific toy, with the "pile" being constructed from fruit. These toys use some strips of copper and zinc inserted in a piece…

  14. Research on method of pressure grouting piling of driven tube

    Institute of Scientific and Technical Information of China (English)

    Dianqi PAN; Zupei ZHANG; Diancai PAN; Yong CHEN; Maosen TAN

    2006-01-01

    The pressure grouting pile of driven tube can improve the load bearing capacity of the single pile from the mechanism of pressure grouting pile of driven tube. On the basis of analyzing the mechanism, the authors designed the machines and tools of pressure grouting, determined the operating manufacture and technology parameter on the pressure grouting secondly. The result shows that the pressure grouting pile of driven tube not only changes the pile type but also reduce the length of the pile and its engineering cost, it enhances the load bearing capacity of single pile an the same time.

  15. Mesomechanical analysis of bearing characteristics of pile-supported embankment with particle flow code%桩承式路堤承载特性颗粒流细观模拟

    Institute of Scientific and Technical Information of China (English)

    郑俊杰; 赖汉江; 董友扣; 张军

    2012-01-01

    Based on a two-dimensional discrete element method program PFC2D, a numerical model was established to simulate the bearing characteristics of pile-supported embankment. The variations of contact forces, stresses, vertical displacements and pile-soil stress ratios were analyzed. Further- more, a parametric study was carried out to investigate the performance of pile-supported embankment and the selected influencing factors consist of the pile spacing, the width of pile cap, the friction angle of cushion and the particle shape of cushion. The numerical results show that the soil arching struc- ture in embankment fill mainly exists above the pile cap of one time clear pile spacing. The wider the pl e cap as well as the smaller the pile spacing are, the higher pile-soil stress ratio but the weaker sta bility of soil arching structure will be. If the surface of soil particle is rougher as well as the friction angle is greater, pile-soil stress ratio will be higher and the stability of soil arching structure will be stronger. With an increase of surcharge loads, the soil arching structure presents a changing process of forming-failure-reforming.%采用离散元法软件PFC2D,建立了桩承式路堤承载特性颗粒流试验模型.分析了路堤荷载下填土颗粒间接触力、应力和竖向位移等的分布规律以及桩土应力比的变化规律,并研究了桩间距、桩帽宽度、颗粒间内摩擦角和颗粒形状等因素对桩承式路堤承载特性的影响.结果表明:填土颗粒中土拱结构主要存在于桩顶1倍桩净间距高度范围内;桩帽宽度越大,桩间距越小,桩土应力比越大但土拱结构稳定性越弱;填土颗粒表面越粗糙,内摩擦角越大,桩土应力比越大且土拱结构稳定性越强;随着路堤荷载的增加,填土颗粒中土拱结构呈现出形成-破坏-再形成的变化规律.

  16. Model test of bearing behaviors of squeezed and branch pile under horizontal periodic loading%水平周期荷载作用下支盘桩受力性状的模型试验

    Institute of Scientific and Technical Information of China (English)

    高笑娟; 李跃辉; 吕冰; 钟国华

    2015-01-01

    为了研究桩在水平动荷载作用下的受力和变形规律,自制了一套能施加动荷载的加载装置,并对两根承力盘位置不同的模型桩进行了水平动荷载试验,研究了桩顶所加荷载幅值、加载频率、承力盘的位置等因素对支盘桩桩身弯矩和桩侧土压力的影响规律。结果表明:随着桩顶荷载幅值的增加,桩身上部正弯矩和弯矩的最大值均呈现增大趋势,桩侧土中压力亦逐渐增大;随着加载频率的增大,桩身上部弯矩先变大,后又减小,土中压力一直呈增大趋势;承力盘位置靠上的桩在同样条件下桩身正弯矩和最大弯矩值较小,桩侧土中的压力也较小。%A dynamic loading equipment was made to study the load bearing capacity and deformation law of model pile under periodic load. In this paper the horizontal periodic load tests of two model piles with different plate position were carried out in the self-made soil box. The influence of the load amplitude, loading frequency, position of plate on the pile section moment and soil pressure were researched. The results show that the moment in pile body and the maximum moment increase with the increasing of load amplitude, and the soil pressure also in-crease at the same time. With the increase of the loading frequency, the moment in pile body increases firstly but decreases later, and the soil pressure keeps increasing. For the two model piles with different plate position, the moment in pile body and the soil pressure of the pile with plate nearer pile top are less than that of the other pile. Those results may be used in the practical engineering.

  17. Bear

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The famous physicist made for his scholars this riddle. A fellow encountered a bear in a wasteland. There was nobody else there. Both were frightened and ran away. Fellow to the north, bear to the west. Suddenly the fellow stopped, aimed his gun to the south and shot the bear. What colour was the bear?

  18. 不同土质情况下机械连接竹节桩的承载力对比分析%Comparative Analysis on Bearing Capacity of Mechanical-connection Bamboo Joint Pile in Different Soil Conditions

    Institute of Scientific and Technical Information of China (English)

    施卫力; 杨成斌

    2015-01-01

    Mechanical‐connection bamboo joint pile has been used in different soil conditions and showed significant effect . In this paper , we carried out contrast test analysis of the mechanical connection bamboo pile with the conventional pipe pile in different soil vertical ultimate bearing capacity and anti pulling capacity .. T he results show that the bearing capacity of composite pile mechanical connection in different soil conditions is obviously higher than that of the conventional pipe .%机械连接竹节桩已在不同土质工程中得到应用且效果显著。本文将机械连接竹节桩与传统管桩在不同土质中的竖向极限承载力和抗拔承载力分别进行了对比性试验分析。结果表明,在不同土质情况下机械连接竹节桩的承载力比传统管桩有明显的提高。

  19. Experimental study on pile-end post-grouting piles for super large bridge pile foundations

    Institute of Scientific and Technical Information of China (English)

    Weiming GONG; Guoliang DAI; Haowen ZHANG

    2009-01-01

    The application of pile-end post-grouting piles for super-large bridge pile foundations in some important projects was introduced in this paper. There are totally 21 test piles. The maximum pile diameter varies from 2.5 m to 3 m, and the maximum length is 125m; the bearing capacity of the post-grouting piles is over ten thousands tons. Based on the test results, the bearing capacity,displacement, and beating characteristics before and after grouting were analyzed. The results show that the beating capacity of the piles is increased in different degrees after grouting although the technical parameters, including the patterns of grouting pipes, pressure, dosages of cement, duration of grouting lasting time, are different. However,the obtained values are very discrete. In addition, the calculation formula for the post-grouting piles under specified grouting condition was deduced based on the statistics analysis results of 57 test piles. The research results have been applied in the design of bridge foundation.

  20. EXPERIMENTAL STUDY ON BEARING PERFORMANCE OF STEEL PIPE PILE COMPOSITE FOUNDATION CONSTRUCTED BY TOP-DOWN METHOD UNDER VERTICAL LOADS%钢管桩逆作复合基础竖向承载性能试验研究

    Institute of Scientific and Technical Information of China (English)

    周儒夏; 龚维明; 杨乐; 柏平

    2012-01-01

    Model tests were designed to investigate the bearing capacity properties of composite steel pipe pile foundations in sandy soil.Results indicated that:To a single pile composite foundation,the load was totally carried by ground under the cap before sealing piles.Then,after sealing,the pile started to work and the pile-soil load share ratios were between 73.5%~92% before reaching ultimate bearing capacity.As vertical load increased continually to the capacity limit,the ratio reduced obviously.To a composite foundation with 8 steel pipe piles was tested,the attenuation gradient of axial load was larger in the middle and lower parts rather than the upper part during axial load transfer.The rates of the corner piles were biggest,then the side piles.The side frictional resistances developed gradually from the top to the bottom and the maximum value reached at the distance of 1.55 m below the top.At every load step,the resistances of the corner piles were greater than that of side piles.Moreover,the ultimate bearing capacity of the steel pipe pile composite foundation was significantly higher than that of the high-rise cap pile group foundation.%为了研究砂性土中钢管桩复合基础的承载特性,设计了模型桩系列试验。结果表明:对于单桩复合基础,封桩前阶段的荷载全部直接由承台底砂土承担,封桩后阶段桩体达到极限承载力之前,桩体分担的荷载占荷载增量的73.5%~92%,当桩的承载能力达到极限后,随着荷载的继续增加,桩分担的荷载比例较之前衰减明显,而土体分担的荷载比例增加。钢管桩八桩复合基础中,桩身轴力在桩身上部的衰减梯度明显小于中下部,角桩衰减速率最大,边桩次之;桩身摩阻力自上而下逐渐发挥,桩顶以下1.55 m处摩阻力达到最大;每级荷载作用下,角桩的侧阻力大于边桩。钢管桩群桩复合基础的竖向承载力远大于相对应的高承台群桩承载力。

  1. Theoretical solution for time effect of shaft bearing capacity of single pile in soft soils%软土中单桩桩侧承载力时效性理论解

    Institute of Scientific and Technical Information of China (English)

    曹权; 施建勇; 雷国辉; 艾英钵; 陈鸿

    2011-01-01

    以有效应力原理为基础,结合考虑应变软化、桩径和弹性区孔压分布等因素的桩周土固结解,推导出软土中单桩桩侧承载力时效性的理论解.与传统桩的承载力时效性简化分析方法不同,该理论解不仅考虑了多土层地基中各土层刚度指数的差异对固结过程的影响,还考虑了各土层因固结系数不同对孔压消散速率的影响.通过现场不同间歇期的单桩载荷试验测试结果验证了其合理性.%Based on the theory of effective stress, consolidation solution around the pile which is taken into account the influence of strain softening, magnitude of pile radius and range of excess pore water pressure, a theoretical relationship about time-effect of bearing capacity of single pile is developed, which can be used to predict the variation of shaft bearing capacity of a jacked-in pile with time in saturated soft clay. Different from the traditional way, the effect of different stiffness indices and different consolidation coefficients on the consolidation process in varied clays and highly stratified deposits are considered in the new consolidation solution. Besides, the rationality of the solution is verified by the pile load tests in different time periods after installation.

  2. Pile Model Tests Using Strain Gauge Technology

    Directory of Open Access Journals (Sweden)

    Krasiński Adam

    2015-09-01

    Full Text Available Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model.

  3. Experiments of Multi-element Composite Foundation with Steel Pipe Pile and Gravel Pile

    Institute of Scientific and Technical Information of China (English)

    WANG Xian-zhi; ZHENG Jun-jie

    2008-01-01

    A set of self-developed apparatus for foundation physical model were utilized to conduct model tests of the multi-element composite foundation with a steel pipe pile and several gravel piles. Some load-bearing characteristics of the multi-element composite foundation, including the curves of foundation settlement, stresses of piles, pile-soil stress ratio, and load-sharing ratio of piles and soil, were obtained to study its working performances in silty sand soil. The experimental results revealed that the multi-element composite foundation with steel pipe pile and gravel pile contributed more than the gravel pile composite foundation in improving the bearing capacity of the silty fine sand.

  4. Optimization Mathematical Model of Pile Forces for Offshore Piled Breasting Dolphins

    Institute of Scientific and Technical Information of China (English)

    周锡礽; 王东芹; 王晖; 朱福明

    2004-01-01

    An optimization mathematical model of the pile forces for piled breasting dolphins in the open sea under various loading conditions is presented. The optimum layout with the well distributed pile forces and the least number of piles is achieved by the multiplier penalty function method. Several engineering cases have been calculated and compared with the result of the conventional design method. It is shown that the number of piles can be reduced at least by 10% ~ 20%and the piles' bearing state is improved greatly.

  5. Static and dynamic pile testing of reinforced concrete piles with structure integrated fibre optic strain sensors

    Science.gov (United States)

    Schilder, Constanze; Kohlhoff, Harald; Hofmann, Detlef; Basedau, Frank; Habel, Wolfgang R.; Baeßler, Matthias; Niederleithinger, Ernst; Georgi, Steven; Herten, Markus

    2013-05-01

    Static and dynamic pile tests are carried out to determine the load bearing capacity and the quality of reinforced concrete piles. As part of a round robin test to evaluate dynamic load tests, structure integrated fibre optic strain sensors were used to receive more detailed information about the strains along the pile length compared to conventional measurements at the pile head. This paper shows the instrumentation of the pile with extrinsic Fabry-Perot interferometers sensors and fibre Bragg gratings sensors together with the results of the conducted static load test as well as the dynamic load tests and pile integrity tests.

  6. 粒料桩复合地基承载力发挥值试验研究%Experimental Study on Efficiency Factor of Bearing Capacity of Granular Pile Composite Foundation

    Institute of Scientific and Technical Information of China (English)

    轩勇; 刘军勇

    2013-01-01

    结合实体公路工程,通过现场试验段土压力监测,计算复合地基承载力发挥值;结合破坏模式,对其复合地基承载力发挥值进行分析.研究结果表明:粒料桩复合地基按照土体先破坏计算的复合地基承载力发挥值,接近现场载荷试验结果,复合地基承载力可通过桩墩间土压力进行计算确定;不论是强夯置换砾石墩还是振动砾石桩,其破坏形式是桩(墩)间土先破坏引起的整个复合地基的破坏.%Combining with substantial highway engineering,efficiency factor of bearing capacity of composite foundation was calculated through soil pressure monitoring at the section for site test and,with failure mode,it was analyzed as well.The study result shows that for granular pile composite foundation,the efficiency factor of bearing capacity calculated in terms of earth mass failure taken place first is close to the result of on-site load test and the bearing capacity may be calculated through soil pressure between piles/piers.In addition,the failure mode is such that the whole composite foundation is destroyed in the event that the soil between piles (piers) is destructed at first,regardless of dynamic replacement gravel pier or vibration gravel pile.

  7. A p-y curve method for horizontal bearing characteristics of single batter pile in sands%砂土地基斜桩水平承载特性p-y曲线法

    Institute of Scientific and Technical Information of China (English)

    凌道盛; 任涛; 王云岗

    2013-01-01

    Based on the p-y curve method for plumb pile in sand proposed by Reese, a new p-y curve method and its corresponding finite element method for analyzing horizontal bearing characteristics of single batter pile are presented. Firstly, according to the mechanical behavior of the shallow soil near a batter pile, a three-dimensional wedge model is put forward to describe the passive region which is in the limit state. By using limit equilibrium analysis method, the expression of ultimate soil resistance of batter pile is derived. Then, the influences of pile angle and the friction between pile and soil are numerically studied; and the method for determining the initial modulus of p-y curve of batter pile is given. By modifying the p-y curve for plumb pile in sands proposed by Reese, the p-y curve for batter pile in sand is obtained. Using the virtual work principle, the finite element formulations for horizontal bearing analysis of single batter pile are deduced; and the iteration algorithm is put forwards. The corresponding program is coded by authors; and numerical examples are taken to illustrate the effectiveness of the method. Finally, a printed centrifuge model test of batter pile is analyzed by the presented method. The numerical results show fine agreement with those of model test.%基于Reese建议的砂土p-y曲线,提出了适用于斜桩水平承载特性分析的修正p-y曲线及相应的有限元分析方法.根据桩前土体受力特点,假设桩前浅层土体达到极限破坏状态时桩侧被动破坏区为一个三维楔形体,采用极限平衡分析方法导出了斜桩桩侧极限土抗力表达式,对比研究了斜桩倾角、桩-土界面摩擦系数等因素对极限土抗力的影响规律,并给出了斜桩初始地基反力模量确定方法.在此基础上,修正Reese提出的直桩p-y曲线,提出了砂土地基中斜桩p-y曲线确定方法.利用虚功原理,导出了斜桩水平承载特性分析的有限单元列式,编制相应

  8. Determining the pile bearing capacity by the curve match method of high strain dynamic testing%确定基桩承载力的高应变实测曲线拟合法

    Institute of Scientific and Technical Information of China (English)

    王秉宇; 崔建波; 王士杰; 孙东岭

    2012-01-01

    采用高应变实测曲线拟合法确定基桩承载力及桩侧摩阻力的分布,通过基桩承载力动、静试验结果的对比,分析了高应变实测曲线拟合法的测试精度和可靠性,探究了高应变动测法确定基桩承载力的误差来源及因由,为合理确定桩基工程设计参数提供可靠保证.%This essay will determine, the bearing capacity of the pile and shaft resistance by the curve match method of high strain dynamic testing. By the pile of bearing capacity of the contrast between the testing results of static loading and dynamic high strain, analyses the reliability and surveying precision of the curve match method and exdores the error sources and reason, which reasonably determine the pile foundation engineering of design parameters.

  9. Analysis of the Effect of Pile Skin Resistance Verses Pile Diameter Based on Experimental Research

    Directory of Open Access Journals (Sweden)

    S. M. Marandi

    2009-01-01

    Full Text Available In spite of the many recent advances in pile design and execution methods, the quantitative effects of grouted pile skin resistance and form on subsequent pile behavior remains an area for research. There are many parameters involved in the analysis of the bearing capacity of piles and descriptive method theory of the loading effect for each parameter is very complex. Many of these parameters are interrelated and investigation of the relationships leads to complex equations, which cannot be easily solved. The only reliable solution is to study the influence of each parameter by experimental model tests in equipped laboratories. This research presents the results of static compression tests on two model groups of pipe and grouted pile shafts (35mm, 50mm and 60 mm in diameters and 900 mm in length installed into beds of Yazd siliceous sand (located in southeast Iran. The findings of the experimental research were to the average ultimate loads at failure for grouted piles were approximately 12% higher than for the pipe piles. The pile skin resistance is an effective factor on pile bearing capacity, the load transfer response appears to be more plastic with increasing pile diameter in siliceous sand and the skin resistance of the pile was not linearly proportional to the pile diameter and varied with increase in pile diameter.

  10. Experimental study on enhancing bearing capacity of marine soft soil foundation with cement-mixing piles%水泥土搅拌桩增强海相软土地基承载力的试验研究

    Institute of Scientific and Technical Information of China (English)

    吕田丰

    2015-01-01

    为了研究本地区海相软土地基采用水泥土搅拌桩进行加固技术,提高海相软土地基承载力的可行性。选取了本地区典型的海相软土场地,采用水泥土搅拌桩对软土地基进行加固,利用浅层平板载荷试验和复合地基载荷试验的方法,对海相软土加固前后的地基承载能力进行了比较分析。结果表明,利用水泥土搅拌桩对海相软土地基进行加固,可以有效地增强海相软土地基承载力。%In order to study the feasibility of improving bearing capacity of marine soft soil foundation through the technique of reinforcing local marine soft soil foundation with cement-mixing piles,we select typical marine soft soil site and reinforce the soft soil foundation with cement-mixing piles.Through super-ficial plate loading test and composite foundation loading test,we conduct comparative analysis on the bear-ing capacities of marine soft soil foundation before and after the reinforcement.Results show that reinfor-cing marine soft soil foundation with cement-mixing piles can improve the bearing capacity effectively.

  11. Prediction of Vertical Ultimate Bearing Capacity and Dynamic Stability Analysis of Super-Long Pile%超长桩竖向极限承载力预测与动力稳定性分析

    Institute of Scientific and Technical Information of China (English)

    姚文娟; 钟倩倩; 郭志兴; 胡宝琳; 仇元忠

    2011-01-01

    Based on the catastrophe theory, a cusp catastrophe model of super-long pile under vertical sta-tic load was established, and the predictor formula was derived. Based on the above analysis, dynamic load was tested, the double cusps catastrophe model of super-long pile under combined load was proposed and used in the analysis of the dynamic stability. Dynamic analysis showed that; The relationship among the amplitude H, the Frequency q and the nonlinear coefficient a was conformed to the double cusps ca-tastrophe model when combined load was applied on super-long pile; there was a certain relationship a-mong the change value of dynamic loading frequency, the previous deformation value of pile and the non-linear coefficient of systems in the process of destabilization of super-long pile; important influence on the response characteristics of super-long pile was obtained under the different dynamic loading path. Project example results show that: the cusp catastrophe model is applicable in predicting vertical ultimate bearing capacity of super-long pile.%应用突变理论建立了超长桩在竖向静荷载作用下的尖点突变模型,推导得到了超长桩的竖向极限承载力预测公式.在静荷载分析的基础上,引入动荷载,建立了超长桩在动静组合荷载作用下的双尖点突变模型,并对其动力稳定性进行了分析.动力分析表明:动静组合荷载作用下超长桩的振幅H、频率关系q与结构非线性系数a三者之间符合双尖点突变模型;超长桩失稳时动载频率的变化值与桩顶预变形值及系统非线性系数有一定的关系;动载作用“路径”对超长桩的响应特征有很大的影响.工程算例表明:应用尖点突变理论对超长桩的竖向极限承载力进行预测具有较好的适用性.

  12. 水平荷载作用下高承台管桩的荷载传递性状及承载力研究%Load Transfer and Bearing Capacity of High-Cap Pipe Piles under Horizontal Load

    Institute of Scientific and Technical Information of China (English)

    雷华阳; 刘利霞; 霍海峰; 陆培毅; 付瑞清; 付海峰

    2012-01-01

    exposing height is less than 1.7m. ultimate horizontal bearing capacity of high cap pipe piles stays constantly, when the exposing height is more than 1. 7 m, it decreases rapidly. Increasing the soil strength, the modulus and diameter of piles could be favorable to the horizontal bearing capacity, while changing the length has little influence.

  13. 单桩竖向抗拔承载力离心模型试验研究%Centrifugal Model Test on the Vertical Uplift Bearing Capacity of Single Pile

    Institute of Scientific and Technical Information of China (English)

    任国峰; 徐光明; 顾行文

    2012-01-01

    To assist the design of pile foundation of an offshore wind farm, centrifuge modeling is performed to determine the uplift bearing capacity of single ultra-long steel pipe-pile of large diameter by which the wind turbine foundation is constituted. Curve of load versus displacement ( Q-S curve) deducted from the results of centrifuge model test are compared with that from prototype uplift capacity test. The effect of loading manner and loading rate on the ultimate uplift bearing capacity is discussed. It is shown by comparison that the value of ultimate uplift bearing capacity of single pile from centrifuge test is greater than that obtained from prototype test. As higher rate usually mobilizes higher strength, a higher loading rate in the centrifuge model test is regarded as the cause of the difference between two test results.%结合某海上风电场桩基工程中的大直径超长钢管桩抗拔承载力研究,利用离心模拟技术,初步推求得出荷载-位移的关系曲线(即Q-S曲线),并与现场抗拔试验成果得出的Q-S曲线进行了比较,分析两者加载方式和加载速率的不同对Q-S曲线的影响.结果发现,上拔力的加载速率较快,求得的单桩抗拔极限承载力偏高.

  14. 关于有黏结强度增强体复合地基承载力深度修正的讨论%DISCUSSION ON DEPTH MODIFICATION OF COHESIVE PILE COMPOSITE FOUNDATION BEARING CAPACITY

    Institute of Scientific and Technical Information of China (English)

    吴迈; 侯伟明; 王恩远

    2014-01-01

    Depth modification of the bearing capacity of a composite foundation involves project safety and investment.Due to lacking research and unified understanding in that issue , and based on the regulations of Technical Code for Ground Treatment of Buildings (JGJ 79—2012) and related points of view in The Understanding and Use of the Technical Code ( JGJ 79—2012 ) , the substance of depth modification of cohesive-pile composite foundation was analyzed and , two methods to predict the modified bearing capacity of pile and soil between piles were deduced .The suitability of the two methods was testified by an example , the principle and method to revise the bearing capacity were also presented .%复合地基承载力深度修正问题,事关工程的安全和投资。但目前对这一问题的研究不足,认识并不统一。基于JGJ 79—2012《建筑地基处理技术规范》的规定和《建筑地基处理技术规范理解与应用》(按JGJ 79—2012)的观点,辨析有黏结强度增强体复合地基承载力深度修正的实质,导出考虑深度修正的桩身和桩间土承载力的两种计算方法。结合算例对该两种方法的适用性予以验证,最后提出有黏结强度增强体复合地基承载力深度修正的原则和方法。

  15. 预应力管桩单桩极限承载力动静测试研究分析%Study and analysis on activity test of prestressed pipe pile ultimate bearing capacity of single pile

    Institute of Scientific and Technical Information of China (English)

    邵晶晶

    2011-01-01

    结合某工程,在同一场地,对不同桩长条件下的预应力混凝土管桩进行了静载荷和动力测试对比试验,取得了一些对比资料和实测成果,并对其原因进行简要分析,从而得出了一些有益的结论,具有一定指导意义。%Combining with a project, this paper made static load and dynamic test contrast test to prestressed concrete pipe pile at the same site and for different pile long, gained some contrast materials and the measured results, and briefly analysed the reasons, so as to abtain some useful conclusions, had some guiding significant.

  16. Tension Tests On Bored Piles In Sand

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Clausen, Johan; Damkilde, Lars

    2006-01-01

    The lengths of the bored piles varied from 2 m to 6 m and all were of a diameter of 140 mm. The piles were tested to failure in tension and the load-displacement relations were recorded. The investigation has shown pronounced differences between the load bearing capacities obtained by different...

  17. Test Research on Vertical Bearing Capacity of Bored Pile Reinforced by High Pressure Jet Grouting%旋喷加固灌注桩竖向抗压承载性能试验研究

    Institute of Scientific and Technical Information of China (English)

    于宝来

    2015-01-01

    In the reconstruction and restoration project , the ground treatment which improves the bearing capacity of bored pile can obtain much more economic benefit and engineering efficiency .However, relatively less research has been carried out on the combined application of ground treatment and bored pile .Based on the data of in-situ static load tests , the laws of load-displacement curve , internal force , and soil friction resistance of single pile were discussed .The test results show that the load transfer mechanism of bored piles is the same each other .The vertical bearing capacity of bored pile reinforced by high pressure jet grouting is significantly im-proved, and the displacement is less under the same load .The skin friction resistance is enhanced by high pres-sure jet grouting .The effect of high pressure jet grouting reinforcement to shallow soil is larger than that to deep soil, and the skin friction resistance of silty soil grows larger than that of clay soil .%城市建筑改造和修复工程发展迅速,钻孔灌注桩和地基处理的联合应用能有效地解决施工条件限制和承载力的要求,提高经济效益和工程效率。目前二者联合应用的实例和研究相对较少。通过现场试验,对高压旋喷地基处理前后相同规格的钻孔灌注桩进行荷载试验,对比分析旋喷处理前后灌注桩的荷载-沉降曲线、极限承载力及桩侧摩阻力分布等规律。结果表明,旋喷加固前后灌注桩竖向荷载传递规律相似;旋喷加固后灌注桩的竖向极限承载力提高,相同荷载下沉降降低;高压旋喷提高了土体侧摩阻力,旋喷对浅层土的加固效果高于深层土,对粉土侧摩阻力的提高效果要高于黏性土。

  18. Influential Study on Wave Loading to Vertical Bearing Capacity of Wharf Pile Foundation%波浪荷载对码头桩基竖向承载力的影响研究

    Institute of Scientific and Technical Information of China (English)

    袁伟; 闫澍旺; 赵亮

    2011-01-01

    The soil around pile foundation in the wharf will suffer from strength reduction under the cycle wave loading conditions, which would further influence the vertical bearing capacity of the pile foundation. Through the indoor dynamic biaxial GDS to simulate' the cycle wave loading and apply these loads to the soil sample of Tianjin port, the strength reduction laws of soil under the dynamic cycle loads in different depths are obtained. Next, with the help of ABAQUS, combining the working loads with cycle wave loading on the pile foundation, the distribution laws of soil dynamic stress around the pile are analyzed. After synthesizing the dynamic biaxial test, the final results are obtained, which show the soil suffered from strength reduction spreads to the depth up to 5 m, the maximum strength reduction rate nearby soil can reach 85.3 % and the vertical bearing capacity of wharf pile foundation reduction rate is 5.73 % .%码头桩基在波浪循环荷载的长期作用下,桩周一定范围的土体会出现强度弱化,进而会一定程度的影响基桩竖向承载力.该文首先通过室内GDS动态三轴仪对天津港码头地基土样作用模拟的波浪循环荷载,研究不同深度土体受到不同幅值的循环动应力荷载作用后其强度的折减规律.然后通过ABAQUS有限元软件计算模拟码头桩基在上部既有结构相互作用的同时,桩身上部受波浪循环荷载,桩周土动应力的分布规律.结合室内动三轴试验结果,计算得到该码头桩基在波浪循环荷载作用下桩周土体弱化的影响深度约为5m,桩周土体的强度折减率最大达到85.3%,码头桩基竖向承载力的折减率为5.73%.

  19. Application of Finite Element Method in Calculating the Bearing Capacity of Pile Boots%有限元法在桩靴承载力计算中的应用

    Institute of Scientific and Technical Information of China (English)

    王楠; 朱龙海; 姜胜辉; 胡日军; 徐永臣

    2014-01-01

    Pitching pile of self elevating drilling platform is a dynamic process of continu-ous plastic damage of foundation soils in the pile shoe loads .When the ultimate bearing capacity of foundation equals to the load on pile boots ,the pile pitching is completed . Because the classical theory of limit bearing capacity of soil mechanics has made assump-tions to the sliding surface hidden in the soil body ,the damage process occurring inside the soil could not be analyzed efficiently .For this reason ,the finite element method (FEM ) is used to simulate the pile pitching process ,by w hich the failure mechanism of foundation soils and the stress-strain of subsoil body under a middle load are obtained . By comparing with the ultimate bearing capacity calculated by using different theoretical formulae ,the factors influencing the ultimate bearing capacity of foundation soils are analyzed .T he results reveal that the larger the B/H ratio is ,the easier the plastic dam-age occurs in the underlying soft stratum .As a result ,the ultimate bearing capacity re-duces obviously .When the value of B/H is less than 0 .286 ,the influence of the under-lying soft stratum on the ultimate bearing capacity of foundation soils can be ignored .%自升式钻井平台插桩是地基土在桩靴荷载作用下发生连续的塑性破坏的动态过程,当地基极限承载力等于桩靴荷载时插桩完成。经典土力学极限承载力理论对土体潜在滑动面做了假设,无法有效分析土体内部的破坏过程。本研究应用有限元法(FEM )对插桩过程进行了模拟,得到地基土的破坏机制以及中间荷载下土体的应力、应变情况,通过和各理论公式计算的极限承载力进行对比分析,分析影响地基极限承载力的因素。研究表明,基础宽度与硬土层厚度的比值 B/H越大,下卧软土层越容易发生塑性破坏,极限承载力明显下降,当B/H<0.286时,可以忽略下卧软土层对地基承载力的影响。

  20. Analysis & Calculation on Axial Compression Allowable Bearing Capacity of Rock-Socketed Pile in Xiamen City%厦门地区嵌岩桩单桩轴向受压容许承载力分析计算*

    Institute of Scientific and Technical Information of China (English)

    马朝旭; 刘世忠; 杨子江

    2013-01-01

    依照厦门市疏港路下穿仙岳路通道工程地质勘测资料,根据公路规范、建筑规范和福建省当地规范对基坑开挖过程中单排围护桩的单桩轴向受压容许承载力进行计算,并对各规范计算值进行分析比较。同时结合大型有限元软件 ANSYS建立桩基础三维弹塑性模型分析桩土共同工作机理,将规范计算值以面荷载的形式在模型中施加于桩顶,对此荷载下的桩体位移和桩底反力进行计算分析,同时对门机轴向荷载作用下的桩顶位移实测值和模型计算值进行对比分析,得出在规范计算值范围内,桩体未发生破坏。结果表明各个规范公式在计算桩基轴向受压容许承载力时对岩土参数取值各异,采用的计算模式存在差异,因此规范计算值差别较大,ANSYS模型数值分析结果与现场实测结果吻合良好,可为该地区桩基础设计提供参考。%According to the channel construction engineering geology survey material of Xianyue Road and Shugang Road in Xiamen,the axial compression allowable bearing capacity of fender pile in the process of excavation is calculated by highway criterion,building code and local regulations in Fujian Province and all standard calculation values are compared.With the large finite element software ANSYS,the pile founda-tion three-dimensional elastic-plastic model is established to analyze the pile and soil common working mechanism.The model uses the standard calculation value as the surface load applied to the pile and gets the displacement of the pile and the reaction at the bottom of pile.The displacement of pile under the axial load of the crane is also measured and analyzed.It is found that the pile foundation is not destroyed in the range of standard calculation values.The results show that all codes adopt different geotechnical parame-ters and the calculation method is different,so the difference of standard calculation values is big

  1. 基于贝塔分布的抗拔桩承载力可靠度分析%Reliability analysis of bearing capacity for anti-uplift piles based on Beta distribution

    Institute of Scientific and Technical Information of China (English)

    徐志军; 郑俊杰; 边晓亚; 赵文艺

    2012-01-01

    The bearing capacities of 12 anti-uplift piles were collected,and the probability distribution of partial factor(the ratio of the measured values of bear capacity of anti-uplift piles and their corresponding calculated values) was fitted utilizing Beta distribution.The results through the K-S test indicate that the fitting accuracy employing Beta distribution is better than employing normal distribution,lognormal distribution and extreme value I distribution.The results from calculation of reliability indices based on Monte Carlo simulation method show that the mean of partial factor,loading combinations,loading ratios and factors of safety have significant influence on reliability indices,while the reliability index is insensitive to coefficient of variation of partial factor.Finally,the resistance factors of anti-uplift piles were given according to load and resistance factor design method.%以12根抗拔桩承载力为研究对象,利用4参数的贝塔分布拟合出抗拔桩承载力试计比(承载力实测值和计算值的比)的概率分布.通过K-S检验法检验指出:贝塔分布的拟合精度优于常见的正态分布、对数正态分布和极值I型分布.利用蒙特卡罗法计算出抗拔桩承载力的可靠度指标,计算结果表明:承载力试计比的均值、荷载组合、荷载比和安全系数对可靠度有显著的影响.最后利用荷载抗力系数设计法给出了抗拔桩的抗力系数.

  2. 灌注桩钢筋笼长度对承载力的影响%The bearing capacity of pile length of reinforcing cage of inlfuence

    Institute of Scientific and Technical Information of China (English)

    王东; 马青龙; 王德庆

    2015-01-01

    The uplift pile for foundation under pulling force is a common practice of engineering. In some deep underground engineering, the bored piles can provide higher pull-out force, reinforced concrete pile and the soil is a good way to combine, make the uplift capacity of pile with good performance. But in actual project, the contractor to save costs, fail to execute the works in accordance with the drawings, to reduce the length of reinforcing cage, brings to the engineering quality hidden trouble.%抗拔桩来承担基础承受的上拔力是工程界常见的做法.在一些较深的地下工程中,钻孔灌注桩能提供较高的抗拔力,钢筋混凝土桩身与土层可以很好地结合 ,使这种桩具有良好的抗拔性能.但在实际工程中,施工方为节约成本,未能按照图纸施工,减少钢筋笼的长度,给工程质量带来隐患.

  3. 高承载素混凝土桩复合地基现场试验研究%Field tests on high-bearing composite foundation with plain concrete piles

    Institute of Scientific and Technical Information of China (English)

    陶景晖; 梁书亭; 樊有维; 张永乐; 陶茂之

    2012-01-01

    某高层建筑采用素混凝土桩复合地基。基坑开挖后,进行了多项原位载荷试验以及桩、土应力测试;在建造过程中,进行了沉降观测,并对复合地基应力变化做了跟踪测试。基于试验数据,对复合地基的工作机理、荷载分担特性、桩身应力分布特征、基础沉降特点等进行了分析,并探讨了桩底后注浆工艺对复合地基工作性状的影响。研究表明:素混凝土桩复合地基具有高承载力和低变形的性能;非挤土成桩工艺增强体,对桩问土也具有加固效果;采用桩底后注浆工艺,可提高复合地基承载力、减小变形,加固效果在高荷载水平下较好;基础底板及上部结构刚度对桩的不均匀受力具有一定的调整能力。提出了根据荷载和地基反力分布状况,采取针对性的变刚度调平措施的建议。%The composite foundation with plain concrete piles is applied in the construction of a high-rise building. Various in-situ loading tests and stress tests of piles and soil are performed after excavation of foundation pits. The settlement and stress variations of the composite foundation are monitored during the construction period. Based on the test data, the work mechanism, load sharing characteristics of composite foundation, stress distribution of the piles, and settlement characteristics of the foundation are analyzed. Moreover, the effects of post-grouting technology of the piles on the work performances of the composite foundation are evaluated. The test results indicate that the composite foundation with plain concrete piles exhibits high bearing and small deformation capacities. The reinforcement without soil compaction technology has a reinforcing effect on the soil among piles. The application of post-grouting technology can improve the bearing capacity and reduce the settlement of the composite foundation, and high loading level may result in better reinforcing

  4. Pile Model Tests Using Strain Gauge Technology

    Science.gov (United States)

    Krasiński, Adam; Kusio, Tomasz

    2015-09-01

    Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model. To find a suitable solution for axial force measurement, which could be applied to small scale model piles, we had to take into account the following requirements: - a linear and stable relationship between measured and physical values, - the force measurement accuracy of about 0.1 kN, - the range of measured forces up to 30 kN, - resistance of measuring gauges against aggressive counteraction of concrete mortar and against moisture, - insensitivity to pile bending, - economical factor. These requirements can be fulfilled by strain gauge sensors if an appropriate methodology is used for test preparation (Hoffmann [1]). In this paper, we focus on some aspects of the application of strain gauge sensors for model pile tests. The efficiency of the method is proved on the examples of static load tests carried out on SDP model piles acting as single piles and in a group.

  5. 海上风电桩基础竖向承载力循环弱化简化分析%Simplified analysis of cyclic degradation of axial bearing capacity for offshore wind turbine pile foundations

    Institute of Scientific and Technical Information of China (English)

    刘莹; 黄茂松; 李帅

    2013-01-01

    提出了一个考虑循环衰减作用的软黏土弹塑性损伤弱化模型,在此模型基础上建立了一个基于剪切位移法的单桩竖向承载力简化计算方法,并利用大型有限元软件进行了不同循环荷载水平下单桩竖向承载力的计算。为了证明简化方法的准确性与有效性,将计算结果与有限元计算结果进行对比,二者的吻合度较高。先期循环荷载能引起单桩竖向承载力弱化,并且弱化程度随先期循环荷载水平的增加而增加。最后将简化方法应用于某海上风电场桩基础承载力的计算中,结果表明,提出的简化方法可应用于实际工程问题的分析。%A modified undrained elastic-plastic model considering the cyclic degradation of clay soil is proposed. Based on this model, a simplified analysis procedure based on shear displacement method is presented. Numerical simulations for axial bearing capacity of single pile are conducted by commercially available finite element software at different cyclic load levels. The results calculated by this simplified analysis have a good consistency and effectiveness with the results from finite element analysis. The axial bearing capacity of single pile will be degraded after resisting cyclic loading, and the degradation will be greater as the increase of cyclic loading levels. As an example, the axial bearing capacities of pile foundation of an offshore wind farm are studied with the application of the proposed simplified analysis method. The proposed simplified calculation method will serve as a useful tool for engineering design.

  6. Calculation of bearing capacity of socketed pile in extremely soft medium weathered rock%极软质中风化岩嵌岩桩承载力计算方法探讨

    Institute of Scientific and Technical Information of China (English)

    宋兰芳; 卢永昌

    2009-01-01

    对软质中风化岩嵌岩桩承载力,目前规范尚无明确的计算方法,实际工程按JTJ285-2000计算的承载力与高应变实测承载力相差较大,其计算方法已不再适用.结合2个实际工程,对极软质中风化岩(饱和单轴抗压强度标准值小于5 MPa)嵌岩桩承载力计算方法进行探讨,提出合理的计算方法.%For the embedding pile bearing capacity in very soft medium weathered rocks, there are no clearly regulated calculation methods in current codes. In accordance with the rules of "Design and Construction Codes for Port Engineering" the calculated results of the bearing capacity show large deviations against the actually measured result by high strain test, therefore, its ealeulation method is not applicable anymore. On the basis of practices in two projects, this article carried out a preliminary study on the calculation method of embedding pipe bearing eapacity in extremely soft medium weathered rock (with saturated uniaxial compressive strength less than 5 Mpa) .

  7. Application of PCC pile in soil improvement of highway

    Institute of Scientific and Technical Information of China (English)

    刘芝平; 刘汉龙; 谭慧明

    2008-01-01

    The construction process and load-bearing behaviors of Cast-in-place concrete thin-wall pipe piles are analyzed based on its application on Yantong Expressway Project. The low strain test, static load test and field excavation were also carried out, and the bearing capacity of the new pile can meet the requirements of design. With the increase of pile diameter, the bearing capacity is increased. The settlement of composite foundation is decreased, when the replacement ratio of pile is increased. The test results also show that the load carried by inner soils is neglectable. According to the tests and application, it can be concluded that the new type of pile is convenient to construction with high bearing capacity and reliable quality, which has great potential in practical engineering.

  8. THE NUMERICAL ANALYSIS ON BEARING CAPACITY OF CFG PILE COMPOSITE FOUNDATION UNDER BLASTING%爆破地震作用下CFG桩复合地基动力特性的数值分析

    Institute of Scientific and Technical Information of China (English)

    王维玉; 赵拓; 孟艳杰

    2012-01-01

    Through CFG pile composite foundation dynamic test, a test model was built by using finite element analysis software. The analyses were made for the horizontal acceleration, vertical acceleration, horizontal displacement, vertical displacement and stress, which were dynamic response about the same position different depth and the same depth different locations. The analysis results of the dynamic response were in good agreement with the test results. The factors of dynamic response were studied by numerical simulation. Compared with the dynamic response results of natural foundation, we obtained the conclusions in guiding the significance. A basis is supplied for load bearing capacity, deformation and dynamic characteristics of a CFG pile composite foundation.%该文以CFG桩复合地基在爆破地震作用下的现场动力试验为背景,应用有限元软件建立有限元动力分析的数值模拟模型,从水平加速度、竖向加速度、水平位移、竖向位移及应力几个方面对复合地基同一位置不同深度和同一深度不同位置的动力响应进行了分析,其分析结果与试验结果吻合较好.通过数值模拟对动力响应的影响因素进行了比较研究.并与天然地基的动力响应结果进行对比,得出了有指导意义的结论.为今后探讨CFG桩复合地基的承载力、变形和动力特性提供了研究基础.

  9. Assessment of Time Functions for Piles Driven in Clay

    DEFF Research Database (Denmark)

    Augustesen, Anders; Andersen, Lars; Sørensen, Carsten Steen

    The vertical bearing capacity of piles situated in clay is studied with regard to the long-term set-up. A statistical analysis is carried out on the basis of data from numerous static loading tests. The database covers a wide range of both soil and pile properties, which ensures a general....... Hence, it is suggested that a constant set-up factor should be applied for the prediction of pile capacities at a given time after initial driving....

  10. The high strain dynamic test method of foundation pile bearing capacity based on genetic algorithm%基于遗传算法的基桩承载力高应变动测法

    Institute of Scientific and Technical Information of China (English)

    闫明

    2014-01-01

    为了准确得到桩基的承载力,在实测曲线拟合方面提出了采取遗传算法来代替传统人工试凑的方法,以通过编程实现自动求解,并结合工程实例试验,将采用遗传算法的拟合结果与静载荷试验结果作了对比,证实了该方法的可行性与可靠性。%In order to get the accurate bearing capacity of pile foundation,this paper used the genetic algorithm to replace the traditional manual test in measured curve fitting method,through the program realization of automatic solution,and combining with practical engineering test,con-trasted the fitting results and static load test results of genetic algorithm,verified the feasibility and reliability of the method.

  11. Modelling Pile Installation Effects: A Numerical Approach

    NARCIS (Netherlands)

    Engin, H.K.

    2013-01-01

    One of the most traditional methods for supporting structures resting on soft soils is the use of piles. They generally work by transferring the loads to deeper soil layers, which can provide sufficient bearing capacity when mobilised. This type of foundations has been commonly used throughout the w

  12. Mechanical and deformation analyses of pile foundation for supporting structure of off-shore wind turbine at Changhua coast in Taiwan

    Science.gov (United States)

    Wang, W. C.; Lin, D. G.

    2015-12-01

    This study investigates the bearing capacities and mechanical behaviors of pile foundation installed on the seabed of wind farm near Chang-Hua coast of western Taiwan for the supporting structure of offshore wind turbine. A series of three-dimensional (3-D) numerical modeling of pile foundation subjected to various types of combined loading were carried out using Plaix-3D finite element program to investigate the interactive behaviors between soil and pile. In the numerical modeling, pile diameter, pile length and pile spacing were selected as design parameters to inspect their effects on the bearing capacities and deformation behaviors of the pile foundation. For a specific design parameter combination, one can obtain the corresponding loading-displacement curve, various ultimate bearing capacities, V-H (Vertical-Horizontal combined loading) ultimate bearing capacity envelope, and p-ycurve of pile foundation. Numerical results indicate that: (1) Large displacement and plastic points at ultimate state mostly distribute and concentrate in the topsoil of seabed and around pile head. (2) The soil resistance on the soil-pile interface is ascending with the increases of depth, pile diameter and pile length. (3) The vertical and horizontal bearing capacities of pile group increase significantly with the increase of pile diameter. (4) The vertical and bending moment capacities of pile group increase greatly with the increase of pile length whereas the horizontal capacity is almost insensitive to pile length. (5) The bending moment of pile is highly influenced by the pile spacing. (6) For different design parameters, the shape of ultimate bearing capacity envelopes of pile group on V-H plane is similar while the envelopes will expand as the design parameters increase. For different loading levels of bending moment, the envelopes on V-H plane will contract gradually as the bending moment loading increasing.

  13. Method Cement Post-grouting to Increase the Load Capacity for Bored Pile

    Directory of Open Access Journals (Sweden)

    Van Loc Nguyen

    2013-05-01

    Full Text Available Drilled shafts foundations are used as an indispensable solution for long span bridges in Vietnam. In order to increase the bearing capacity, aside from the increasing of the pile length and diameter, an interested way now is treatment of pile bases after concrete placement. This study is aimed at investigating the defect at the bottom of the bored pile from the sonic test. The injection of hight pressure of cement grout to the shaft and tip of the defected bored pile was conducted to increase the bearing capacity of pile. The bearing capacity of defected bored pile is calculated by the TCXD-205:1998 an finite element mothod. After post-grouting technique done, the soil investigation tests have been carried out to define the properties of treated soils. The analytic mothod, finite element method an load test also have been applied to determine the bearing capacity of treated bored pile. The results show that the post-grouting to the shaft and tip of pile can increase two times of bearing capacity of defected bored pile and about 20% compared to the normal bored pile.

  14. Nonlinear calculating method of pile settlement

    Institute of Scientific and Technical Information of China (English)

    贺炜; 王桂尧; 王泓华

    2008-01-01

    To study calculating method of settlement on top of extra-long large-diameter pile, the relevant research results were summarized. The hyperbola model, a nonlinear load transfer function, was introduced to establish the basic differential equation with load transfer method. Assumed that the displacement of pile shaft was the high order power series of buried depth, through merging the same orthometric items and arranging the relevant coefficients, the solution which could take the nonlinear pile-soil interaction and stratum properties of soil into account was solved by power series. On the basis of the solution, by determining the load transfer depth with criterion of settlement on pile tip, the method by making boundary conditions compatible was advised to solve the load-settlement curve of pile. The relevant flow chart and mathematic expressions of boundary conditions were also listed. Lastly, the load transfer methods based on both two-broken-line model and hyperbola model were applied to analyzing a real project. The related coefficients of fitting curves by hyperbola were not less than 0.96, which shows that the hyperbola model is truthfulness, and is propitious to avoid personal error. The calculating value of load-settlement curve agrees well with the measured one, which indicates that it can be applied in engineering practice and making the theory that limits the design bearing capacity by settlement on pile top comes true.

  15. Piles of objects

    KAUST Repository

    Hsu, Shu-Wei

    2010-01-01

    We present a method for directly modeling piles of objects in multi-body simulations. Piles of objects represent some of the more interesting, but also most time-consuming portion of simulation. We propose a method for reducing computation in many of these situations by explicitly modeling the piles that the objects may form into. By modeling pile behavior rather than the behavior of all individual objects, we can achieve realistic results in less time, and without directly modeling the frictional component that leads to desired pile shapes. Our method is simple to implement and can be easily integrated with existing rigid body simulations. We observe notable speedups in several rigid body examples, and generate a wider variety of piled structures than possible with strict impulse-based simulation. © 2010 ACM.

  16. Capacity and failure mechanism of laterally loaded jet-grouting reinforced piles: Field and numerical investigation

    Institute of Scientific and Technical Information of China (English)

    HE Ben; WANG LiZhong; HONG Yi

    2016-01-01

    This study presents the results of field and numerical investigations of lateral stiffness,capacity,and failure mechanisms for plain piles and reinforced concrete piles in soft clay.A plastic-damage model is used to simulate concrete piles and jet-grouting in the numerical analyses.The field study and numerical investigations show that by applying jet-grouting surrounding the upper 7.5D (D =pile diameter) of a pile,lateral stiffness and bearing capacity of the pile are increased by about 110% and 100%,respectively.This is partially because the jet-grouting increases the apparent diameter of the pile,so as to enlarge the extent of failure wedge and hence passive resistance in front of the reinforced pile.Moreover,the jet-grouting provides a circumferential confinement to the concrete pile,which suppresses development of tensile stress in the pile.Correspondingly,tension-induced plastic damage in the concrete pile is reduced,causing less degradation of stiffness and strength of the pile than that of a plain pile.Effectiveness of the circumferential confinement provided by the jet-grouting,however,diminishes once the grouting cracks because of the significant vertical and circumferential tensile stress near its mid-depth.The lateral capacity of the jet-grouting reinforced pile is,therefore,governed by mobilized passive resistance of soil and plastic damage of jet-grouting.

  17. 液压高频振动沉桩的饱和土超静孔压及单桩静载特性试验研究%Experimental studies on pore pressure of saturated soils and bearing capacity of piles driven by high-frequency hydraulic vibrator

    Institute of Scientific and Technical Information of China (English)

    邓俊杰; 陈龙珠; 邢爱国; 宋春雨

    2011-01-01

    为解决常规锤击、电动中低频振动法进行桩基施工时引起较为严重的噪声、振动和增大电网负荷等问题,发达国家已在应用液压高频振动施工技术,但沉桩的土动力学机理以及单桩静力荷载-沉降特性等尚缺乏深入的室内外试验研究.利用大吨位液压高频振动锤,在某深厚饱和软土场地对直径500 mm、长度26~29 m的预应力管桩进行了沉桩施工试验,观测了邻近地基土超静孔压随沉桩深度而上升及其后续消散的过程;在休止期满后进行了单桩怪向静载荷试验,并将实测极限承载力与其它常规施工方法的进行了比较分析.试验结果对推广应用液压高频振动沉桩新技术,具有重要的学术和应用参考价值.%To solve the serious noise and vibration problems as well as the high pressure on the capacity of city power supply caused by the existing piling methods with falling hammers and low-frequency electric vibrators, a new piling technique using high-frequency hydraulic vibrators has been used in some developed european countries and the USA.The piling mechanism related to soil dynamics at high frequency and the bearing capacity of piles after installation with the hydraulic vibrators should be investigated in laboratory and construction sites.Using a high-frequency hydraulic vibrator manufactured by a Shanghai machinery company, pre-casted/pre-stressed concrete pipe piles with diameter of 500 mm and length of 26-29 m are driven into the saturated soft ground in the Minhang campus of Shanghai Jiaotong University in China, and the induced excess pore water pressures of adjacent soil at different depths are investigated for about one month.After the specified interruption period of 28 days after piling, the ultimate bearing capacity of each pile is studied by means of the conventional static loading tests and compared with that of piles installed with falling hammers and statically jetting.The experimental

  18. BEHAVIOR OF LATERALLY LOADED PILE

    OpenAIRE

    Ashish Mehta; P.D.Pachpor

    2010-01-01

    A finite element analysis is done to predict the responses for single pile subjected to lateral load in layered soils, with consideration of pile soil interaction. Pile and soil are simulated by Solid-3D element. In the computational model, contact surfaces between pile and soil are created. The displacements are determined for pile soil system with linearly constants and linearly varying with depth cases is considered. The engineering properties for soil and pile are considered as variable f...

  19. BEHAVIOR OF LATERALLY LOADED PILE

    Directory of Open Access Journals (Sweden)

    Ashish Mehta

    2010-12-01

    Full Text Available A finite element analysis is done to predict the responses for single pile subjected to lateral load in layered soils, with consideration of pile soil interaction. Pile and soil are simulated by Solid-3D element. In the computational model, contact surfaces between pile and soil are created. The displacements are determined for pile soil system with linearly constants and linearly varying with depth cases is considered. The engineering properties for soil and pile are considered as variable for analysis.

  20. Experimental study on DX pile performance in frozen soils under lateral loading

    Institute of Scientific and Technical Information of China (English)

    XiaoBing Liu; LiHong Chen; ZhongYang Yu; JianXiao Hu; Wen Peng

    2013-01-01

    Experiments about working mechanism and mechanical characteristics of the DX model pile foundation under lateral dynamic and static loading were conducted by using a model system of the dynamic frozen soil-pile interaction. The horizontal displacement-force relationship of the pile head and bending moment distribution along the body in frozen soils of different temperatures were discussed. According to test results, both the horizontal displacement-force relationship of the DX pile head and bending moment distribution of the DX pile body are smaller than that of equal-diameter piles under same lateral loads. The piles with different plate positions show different displacements and bending moments. This phenomenon is mainly related to the soil temperature and bearing plates locations. Thus, dynamic response analysis of the pile foundation should be taken into account.

  1. Basal Reinforced Piled Embankments

    NARCIS (Netherlands)

    Van Eekelen, S.J.M.

    2015-01-01

    A basal reinforced piled embankment consists of a reinforced embankment on a pile foundation. The reinforcement consists of one or more horizontal layers of geosynthetic reinforcement (GR) installed at the base of the embankment. The design of the GR is the subject of this thesis. A basal reinforce

  2. Pile foundation of nuclear power plant structures

    International Nuclear Information System (INIS)

    The subject of pile foundation used for nuclear power plant structures, considering the experience gained by the designers of the Angra Nuclear Power Plant, Units 2 and 3 in Brazil is dealt with. The general concept of the pile foundations, including types and execution of the piles, is described briefly. Then the two basic models, i.e. the static model and the dynamic one, used in the design are shown, and the pertinent design assumptions as related to the Angra project are mentioned. The criteria which established the loading capacity of the piles are discussed and the geological conditions of the Angra site are also explained briefly, justifying the reasons why pile foundations are necessary in this project. After that, the design procedures and particularly the tools - i.e. the computer programs - are described. It is noted that the relatively simple but always time consuming job of loading determination calculations can be computerized too, as it was done on this project through the computer program SEASA. The interesting aspects of soil/structure interaction, applicable to static models, are covered in detail, showing the theoretical base wich was used in the program PILMAT. Then the advantage resulting from computerizing of the job of pile reinforcement design are mentioned, describing briefly the jobs done by the two special programs PILDES and PILTAB. The point is stressed that the effort computerizing the structural design of this project was not so much due to the required accuracy of the calculations, but mainly due to the need to save on the design time, as to allow to perform the design task within the relatively tight time schedule. A conclusion can be drawn that design of pile foundations for nuclear power plant structures is a more complex task than the design of bearing type of foundation for the same structures, but that the task can be always made easier when the design process can be computerized. (Author)

  3. Analysis of Negative Skin Friction on Single Pile above a Tunnel

    Institute of Scientific and Technical Information of China (English)

    王志亮; 刘学庆

    2003-01-01

    A finite element program with two different soil models is adopted to study the negative skin friction of an unloaded single pile embedded in the settlement trough of a tunnel. The results show that it is necessary to consider the nonlinear property of soil and to set interface elements between piles and soil in analysis of the negative skin friction of piles. Among a pile group, the pile located above the tunnel centerline bears larger downdrag than the ones far away from tunnel centerline.

  4. 岛状多年冻土地区桥梁桩基回冻后承载力的静载与动测对比试验研究%STATIC AND DYNAMIC CONTRAST TEST FOR BEARING CAPACITY OF REFROZEN BRIDGE PILE FOUNDATION IN PATCHY PERMAFROST REGIONS

    Institute of Scientific and Technical Information of China (English)

    宇德忠; 程培峰; 季成; 崔志刚

    2015-01-01

    为了准确掌握岛状多年冻土地区桥梁钻孔灌注桩的回冻时间及桩基回冻后的承载力,在岛状多年冻土地区选择2个试验地点,每个试验地点浇筑了2根15 m长的试验桩,并在其中一根试验桩处布设温度监测系统,采集桩基回冻过程中的温度数据,根据温度监测结果判断桩基回冻状态,在桩基完成回冻后进行静载与动测试验,测出桩基极限承载力。监测及试验结果表明:试验桩所在区域岛状多年冻土地温约为-1.9℃,桩基完成回冻后桩身内部温度与桩侧1 m处的土体温度变化趋势相同,相同深度处的温差小于0.1℃;用静载法实测出的各土层回冻后的桩侧摩阻力值修正高应变动测法桩–土力学模型中的土层参数,计算曲线与实测曲线拟合较好;动测与静载试验所得到的桩基极限承载力误差为3.91%,试验结果相符合。研究成果可为类似冻土条件下的桩基设计及承载力检测提供理论依据。%To accurately know the refreezing time and capacity of the bridge bored pile constructed in polygonal permafrost regions,two test sites were chosen. Within each site,two 15 m test piles were built. The temperature monitoring system was established in one of the two sites to record and monitor the pile refreezing process. Based on the refreezing condition,static load and dynamic load tests were performed to determine the bearing capacity of the pile. Test results indicate that the mean permafrost temperature is-1.9℃. The trend of temperature change within the pile in refreezing process is similar to that of the permafrost temperature change 1 m beside the pile, which indicates that the difference of temperature change is smaller than 0.1℃. The calculated pile capacity fits well with the testing data by introducing the refreezing pile lateral frictional parameter to modify the soil mechanical model. The capacity error obtains from static load test

  5. Pile Instrumentation Using Retrievable Sensors

    OpenAIRE

    Faisal H. Ali; Bujang B.K. Huat; Lee S. Kai

    2008-01-01

    Strain gauges are normally used to monitor the shortening or compression of pile during static pile load test. For concrete spun pile, the technique used either by incorporating high temperature-resistant strain gauges into the heat-cured production process of the spun piles or by installing an instrumented steel pipe into the hollow core of the spun piles followed by cement grout infilling. The former is extremely unpopular due to high cost of these gauges and the uncertainty over their abil...

  6. Research on Bored Bearing Characteristics in Xi’an

    Directory of Open Access Journals (Sweden)

    Zhang Lipeng

    2015-01-01

    Full Text Available To analyze the influence of different soil properties on pile foundation load-bearing characteristics, taking a section of railway in Xi’an and a bridge of Xi’an as test area, and by field static load test to study load transfer characteristics after the test piles under axial pressure, including the distribution of axial force, pile lateral friction, tip resistance traits, ultimate bearing capacity determine, and compare with the theory bearing capacity. Experimental results show that, adjacent soil properties change large, axial force and lateral friction mutation at the junction of corresponding soil layer. Silty clay in different parts is below ground, and its lateral friction plays much difference. Pile lateral friction plays an important role in bearing capacity, but the role of round gravel soil end bearing capacity to pile bearing capacity can’t be ignored. Tests calculate pile bearing capacity significantly larger than standardized formula calculation bearing capacity, which are respectively 55.35% and 119.1%. And give the similar project condition the suggested values of pile bearing capacity and soil friction, to provide reference for similar pile foundation design.

  7. Comprehensive Detection and Analysis of Defects in Foundation Pile of Bridge

    Institute of Scientific and Technical Information of China (English)

    WANG Qi-ren; HE Ji-shan; YANG Tian-chun

    2003-01-01

    In the process of piling ,there are many various defects in foundation pile of bridge such as mud-bearing,sediment-bearing, isolation, honeycomb, broken piles, and so on, showing physical and mechanical features of low-density and low-intensity. In fact, by using the comprehensive detection of acoustic transmission method, the reflected wave method as well as drill coring sample method, and the rational utilization of engineering geological condition in field, the characteristics, size and location of common defects of foundation pile of bridge can be accurately detected and judged and the integrity of piles and the quality of concrete can be impersonally estimated.comprehensive detecting and analyzing methods on this kind of piles are introduced briefly. The physical characters of defects and basic features of detecting curves and their corresponding relation are emphasized, and causes are analyzed in in detail in this paper.

  8. Seismic Dynamic Damage Characteristics of Vertical and Batter Pile-supported Wharf Structure Systems

    Directory of Open Access Journals (Sweden)

    Li Jiren

    2015-10-01

    Full Text Available Considering a typical steel pipe pile-supported wharf as the research object, finite element analytical models of batter and vertical pile structures were established under the same construction site, service, and geological conditions to investigate the seismic dynamic damage characteristics of vertical and batter pile-supported wharf structures. By the numerical simulation and the nonlinear time history response analysis of structure system and the moment–axial force relation curve, we analyzed the dynamic damage characteristics of the two different structures of batter and vertical piles under different seismic ground motions to provide reasonable basis and reference for designing and selecting a pile-supported wharf structure. Results showed that the axial force of batter piles was dominant in the batter pile structure and that batter piles could effectively bear and share seismic load. Under the seismic ground motion with peak ground acceleration (PGA of 350 Gal and in consideration of the factors of the design requirement of horizontal displacement, the seismic performance of the batter pile structure was better than that of the vertical pile structure. Under the seismic ground motion with a PGA of 1000 Gal, plastic failure occurred in two different structures. The contrastive analysis of the development of plastic damage and the absorption and dissipation for seismic energy indicated that the seismic performance of the vertical pile structure was better than that of the batter pile structure.

  9. Numerical analysis of pile lateral behavior of pile supported embankment

    Institute of Scientific and Technical Information of China (English)

    荆志东; 刘力; 郑刚; 姜岩

    2008-01-01

    A finite difference numerical method was adopted to evaluate the pile lateral behavior of pile supported embankment. A published case history was used to verify the proposed methodology. By simulating the case history, the determination of parameters needed were verified. Then three embankments constructed on different ground conditions with different soil-pile relative stiffnesses were analyzed to study pile lateral behaviors including pile deflection and bending moment. The results show that pile deflections and bending moments induced by soil lateral deformation and embankment vertical load are different for piles at different positions under the same embankment. The relative stiffness between pile and soil affected by the properties of different reinforcing piles such as concrete pile and deep mixing method pile exert important effects on the pile lateral behavior and the pile’s failure modes. Consequently, it is necessary to consider the different piles lateral behaviors and possible failure modes at different positions and the different piles proprieties with different reinforcing methods in the embankment stability analysis.

  10. Soil-Pile Interaction in the Pile Vertical Vibration Based on Fictitious Soil-Pile Model

    OpenAIRE

    Guodong Deng; Jiasheng Zhang; Wenbing Wu; Xiong Shi; Fei Meng

    2014-01-01

    By introducing the fictitious soil-pile model, the soil-pile interaction in the pile vertical vibration is investigated. Firstly, assuming the surrounding soil of pile to be viscoelastic material and considering its vertical wave effect, the governing equations of soil-pile system subjected to arbitrary harmonic dynamic force are founded based on the Euler-Bernoulli rod theory. Secondly, the analytical solution of velocity response in frequency domain and its corresponding semianalytical solu...

  11. Field test study of DX piles%DX桩群桩现场试验研究

    Institute of Scientific and Technical Information of China (English)

    陈立宏; 唐松涛; 贺德新

    2011-01-01

    DX桩(三岔双向挤扩灌注桩)作为一种新型的变截面桩型在承载力和沉降方面比普通直孔灌注桩具有明显的优势.但对于DX桩的承载机制和沉降特性的研究,特别是DX桩群桩的研究还不充分.主要通过现场的模型桩试验,对DX桩单桩和群桩的承载力和沉降特性进行了研究.分析了相同条件下单桩和群桩的特性,同时比较了相同桩长、桩径以及相同承载力条件下DX桩和直孔桩的差异,为DX桩的设计提供了参考.%Cast-in-place pile with expanded branches and bells by 3-way extruding arms (DX pile), a new variable cross-section pile,has obvious advantages in bearing capacity and settlement control compared to conventional pile.However, studies of bearing mechanism and settlement characteristic.especially group DX piles.are not sufficient.The bearing capacity and settlement characteristics of single DX pilc and group DX piles are analyzed via in-situ model test.Special attention is paid on single and group DX piles comparison under same conditions; at the meantime, the single DX pile and conventional pile with the same pile length,diameter, and the same bearing capacity are compared so as to provide the theoretical references for the bearing capacity design of the DX piles in the engineering practice.

  12. FIELD INVESTIGATIONS OF PILED-RAFT FOUNDATIONS WITH SHORT-LENGTH CONIC PILES IN BUILDING AREAS OF MINSK

    Directory of Open Access Journals (Sweden)

    V. A. Sernov

    2015-01-01

    Full Text Available In recent time piled foundations are extensively applied due to an increase of storeys in buildings constructed in Minsk and load increment on the soil. Preference is given to this approach even in the case when relatively firm soil occurs in the top part of the foundation bed. In this case maximum usage of the foundation bed bearing capacity and reduction of foundation cost are considered as top-priority tasks for designers. One of the ways to increase the bearing capacity of piled foundations is the necessity to take into account resistance of foundation bed soil located under raft bottom. The raft as well as a shallow foundation is capable to transfer a significant part of building load into the soil. Such approach makes it possible to reduce a number of piles in the foundation or shorten their length. Then it results in shortening of the construction period and significant reduction in zero cycle. However up to the present moment reliable calculation methods that permit to take into account soil resistance in the raft base. An analysis of previous investigations on the matter executed by various researchers and a number of field investigations have been carried out with the purpose to develop the proposed methods.The paper presents results of field investigations on foundations consisting of short stamped tapered piles which are joined together with the help of the raft fragment. Strength and deformation characteristics of the bases are increasing while making such foundations in the fill-up soil. In this case the filled-up ground layer becomes a bearing layer both for piles and rafts as well. Improvement of high-plastic clay-bearing soil properties is ensured by ramming dry concrete mix under pile foot. The paper describes an experience on application of the piled-raft foundation in complicated engineering and geological conditions while constructing the Orthodox Church in Minsk.

  13. A simplified analysis method for piled raft and pile group foundations with batter piles

    Science.gov (United States)

    Kitiyodom, Pastsakorn; Matsumoto, Tatsunori

    2002-11-01

    A simplified method of numerical analysis has been developed to estimate the deformation and load distribution of piled raft foundations subjected to vertical, lateral, and moment loads, using a hybrid model in which the flexible raft is modelled as thin plates and the piles as elastic beams and the soil is treated as springs. Both the vertical and lateral resistances of the piles as well as the raft base are incorporated into the model. Pile-soil-pile, pile-soil-raft and raft-soil-raft interactions are taken into account based on Mindlin's solutions for both vertical and lateral forces. The validity of the proposed method is verified through comparisons with several existing methods for single piles, pile groups and piled rafts. Workable design charts are given for the estimation of the lateral displacement and the load distribution of piled rafts from the stiffnesses of the raft alone and the pile group alone. Additionally, parametric studies were carried out concerning batter pile foundations. It was found that the use of batter piles can efficiently improve the deformation characteristics of pile foundations subjected to lateral loads.

  14. Design and construction of steel plate pile cofferdam used in bearing platform with embedded rock%嵌岩承台钢板桩围堰的设计与施工

    Institute of Scientific and Technical Information of China (English)

    张芳

    2012-01-01

    In light of geological condition of especially big bridge on Jin-Chi railway,the paper analyzes and compares three kinds of water resisting schemes including vertical shaft,caisson,and steel plate pile cofferdam,determines to apply steel plate pile cofferdam,specifically introduces calculation methods of corresponding design,and describes construction technology.In the end,it summarizes the features and matters needing attention in the construction of steel plate pile cofferdam,with a view to guide similar engineering in future.%针对锦赤铁路洗矿厂特大桥地质条件,对比分析了竖井、沉井、钢板桩围堰三种阻水方案,确定采用钢板桩围堰方案,详细介绍了相关设计计算方法,并对施工工艺作了具体阐述,并总结了钢板桩围堰的特点及施工注意事项,以指导今后同类工程。

  15. Actual Analysis of Bearing Capacity of Piles with Super-large Diameter and Deep Penetration Based on Statnamic Method%基于静动法的大直径超长桩承载力实测分析

    Institute of Scientific and Technical Information of China (English)

    王湛; 刘宇峰; 娄学谦; 戴宇文; 桑登峰

    2014-01-01

    Piles with super-large diameters and deep penetration are widely used in ocean and bridge engineering;however,traditional capacity test methods used for such piles have limitations.Focusing on the imperfections of nor-mal static load and Osterberg cell (O-cell)methods,the statnamic testing method is investigated on the basis of the Second Penang Bridge project in Malaysia.The capacities of piles with super-large diameters and deep penetration in sandy strata are studied.Compared with the results of the O-cell method used on the same pile,the applicability of statnamic testing for super-large diameter,deep-penetration piles is analyzed.Results indicate that the equivalent stat-ic capacities resulting from the Unloading Point Method (UPM)and the Segmental Unloading Point Method (SUPM)are 30% larger than the results when using the O-cell method.Because of the influences of dynamic soil re-sistance and pore pressure,the side friction of statnamic testing is also larger than that when using the O-cell meth-od.Therefore,the statnamic method still requires modification.%大直径超长桩在海洋工程和桥梁工程中应用广泛,但目前常用的测试方法均有各自的局限性。针对普通静载费时费力,自平衡测试方法研究不够完善等不足,基于马来西亚槟城二桥工程,采用现场实测方法对砂土地层中大直径超长嵌岩桩的静动法测试进行研究。通过对同一根桩上的自平衡法测试结果进行对比,分析静动法测试大直径超长桩承载力的适用性。通过对比发现,静动法测试结果用传统卸荷点法和分段卸荷点法处理得到的等效静承载力比自平衡法大30%左右;且由于土动摩阻和孔隙水压力影响,静动法测得的桩身摩阻力也大于自平衡测试结果,需要进行修正。

  16. Development on Carrier Pile Technology%载体桩技术的拓展研究

    Institute of Scientific and Technical Information of China (English)

    杨启安; 王继忠

    2011-01-01

    Through embedding the construction garbage into the bottom of concrete pile and compacting the soil under the pile end, the bearing capacity of carrier pile is improved. In this paper, the load-bearing mechanism of carrier pile technology is studied and the way that the bearing capacity of carrier pile is calculated as equivalent spread footing was put forward. From the composition, construction process, control index, load-bearing mechanism and effect range, carrier pile and rammer pile were compared to distinguish these two kinds. Through changing the size of pile body and bearing carrier to adjust the capacity of carrier pile or reinforcing composite foundation with carrier pile, the field of application was widened.%载体桩技术通过将建筑垃圾置入混凝土桩桩底并夯实,挤密桩端土体而达到提高单桩的承载力.研究了载体桩技术的受力机理,提出了采用等效扩展基础的承载力计算方法.从桩的构成、施工工艺、控制指标、受力原理及施工影响范围等方面对载体桩和夯扩桩进行区别.通过改变载体桩桩身和载体的尺寸进而改变载体桩单桩的承载力,或将载体桩施工成复合地基中增强体,进一步扩大载体桩技术的应用范围.

  17. Laterally Loaded Piles in Clay

    DEFF Research Database (Denmark)

    Christensen, Helle; Niewald, Gitte

    1992-01-01

    The ultimate lateral resistance of a pile element moved horizontally can be analyzed by the theory of plasticity. At a certain depth the movements around the pile are purely horizontal and upper bound solutions can be estimated theoretically under undrained circumstances. Model tests...... in the laboratory show ultimate resistances close to the estimated limits and p - y curves close to curves based on test results from full-scale piles. Rough and smooth piles with circular and square cross sections are investigated....

  18. Static load test and load transfer mechanism study of squeezed branch and plate pile in collapsible loess foundation

    Institute of Scientific and Technical Information of China (English)

    GAO Xiao-juan; WANG Jin-chang; ZHU Xiang-rong

    2007-01-01

    As a special geological phenomenon, the character of collapsible loess foundation is collapsible when penetrated by water. This character leads to the soil losing load bearing capacity largely and may lead to foundation failure. Pile is a popular foundation used in collapsible loess. The squeezed branch and plate pile is a new type of pile developed in recent years and has not be used in a project before. In this paper three squeezed branch and plate piles are tested in collapsible loess after immersion processing. The results may be used for reference in similar construction project, and to provide theoretical references for designing of the squeezed branch and plate piles in engineering practice.

  19. Method Cement Post-grouting to Increase the Load Capacity for Bored Pile

    OpenAIRE

    Loc Nguyen; Lei Nie; Min Zhang

    2013-01-01

    Drilled shafts foundations are used as an indispensable solution for long span bridges in Vietnam. In order to increase the bearing capacity, aside from the increasing of the pile length and diameter, an interested way now is treatment of pile bases after concrete placement. This study is aimed at investigating the defect at the bottom of the bored pile from the sonic test. The injection of hight pressure of cement grout to the shaft and tip of the defected bored pile was conducted to increas...

  20. 非对称异型面剪力墙与简体下的厚承台受力性能研究%Study on load-bearing behaviors of deep pile cap under tube structures and shear walls with asymmetric special-shaped cross sections

    Institute of Scientific and Technical Information of China (English)

    郭宏磊

    2012-01-01

    The experimental analysis, finite element and theoretical studies of the deep pile cap under the shear wall and tube structure with the asymmetric special-shaped cross section are conducted, in which the failure circumstances in the three stages from bending, transition until punching are described. It is pointed out that the main failure modes of this kind of deep pile cap is bending-punching failure with prevailing punching. Load transferring mechanisms of Spatial Strut-and-Tie (SST) is found in the deep pile cap and the complete calculation method of the strut end cross sectional area is put forward furthermore, the proposed method is validated by theoretical bearing-capacity calculation analysis and verification of experiments. The specific principle and method for constructing transfemng load system of SST are explained, the stress concentration phenomenon and diseconomy in the failure attribute of this kind of pile cap are clarified. The research results may aid the engineering design.%进行非对称异型面剪力墙与简体下的厚承台试验、有限元与理论研究;描述该种承台从弯曲到过渡直至冲切三个阶段的破坏情况,指出其为以冲切为主的弯冲破坏;阐述该种承台存在空间桁架传力机理;给出斜压杆端横截面面积的完整计算方法,并经承载力计算分析和试验结果的验证,汪明其合理性;说明构建空间桁架传力体系的具体原则与方法;表明该种承台破坏属性中的应力集中现象及其不经济性。所得结论可对工程设计提供帮助。

  1. Theoretical study on setup of expanded-base pile considering cavity contraction

    Institute of Scientific and Technical Information of China (English)

    齐昌广; 刘干斌; 王艳; 邓岳保

    2015-01-01

    When an expanded-base pile is installed into ground, the cavity expansion associated with penetration of the enlarged pile base is followed by cavity contraction along the smaller-diameter pile shaft. In order to account for the influence of cavity contraction on the change of bearing capacity of expanded-base pile, a theoretical calculation methodology, predicting the setup of expanded-base pile, was established by employing the cavity contraction theory to estimate the shaft resistance of expanded-base pile, and horizontal consolidation theory to predict the dissipation of excess pore pressure. Finally, the numerical solutions for the setup of expanded-base pile were obtained. The parametric study about the influence of cavity contraction on setup of expanded-base pile was carried out, while a field test was introduced. The parametric study shows that the decrements in radial pressure and the maximum pore water pressure after considering cavity contraction are increased as the expanded ratio(base diameter/shaft diameter) and rigidity index of soil are raised. The comparison between calculated and measured values shows that the calculated results of ultimate bearing capacity for expanded-base pile considering cavity contraction agree well with the measured values; however, the computations ignoring cavity contraction are 2.5-3.0 times the measured values.

  2. Theoretical study on setup of expanded-base pile considering cavity contraction

    Institute of Scientific and Technical Information of China (English)

    齐昌广; 刘干斌; 王艳; 邓岳保

    2015-01-01

    When an expanded-base pile is installed into ground, the cavity expansion associated with penetration of the enlarged pile base is followed by cavity contraction along the smaller-diameter pile shaft. In order to account for the influence of cavity contraction on the change of bearing capacity of expanded-base pile, a theoretical calculation methodology, predicting the setup of expanded-base pile, was established by employing the cavity contraction theory to estimate the shaft resistance of expanded-base pile, and horizontal consolidation theory to predict the dissipation of excess pore pressure. Finally, the numerical solutions for the setup of expanded-base pile were obtained. The parametric study about the influence of cavity contraction on setup of expanded-base pile was carried out, while a field test was introduced. The parametric study shows that the decrements in radial pressure and the maximum pore water pressure after considering cavity contraction are increased as the expanded ratio (base diameter/shaft diameter) and rigidity index of soil are raised. The comparison between calculated and measured values shows that the calculated results of ultimate bearing capacity for expanded-base pile considering cavity contraction agree well with the measured values; however, the computations ignoring cavity contraction are 2.5−3.0 times the measured values.

  3. Soil-Pile Interaction in the Pile Vertical Vibration Based on Fictitious Soil-Pile Model

    Directory of Open Access Journals (Sweden)

    Guodong Deng

    2014-01-01

    Full Text Available By introducing the fictitious soil-pile model, the soil-pile interaction in the pile vertical vibration is investigated. Firstly, assuming the surrounding soil of pile to be viscoelastic material and considering its vertical wave effect, the governing equations of soil-pile system subjected to arbitrary harmonic dynamic force are founded based on the Euler-Bernoulli rod theory. Secondly, the analytical solution of velocity response in frequency domain and its corresponding semianalytical solution of velocity response in time domain are derived by means of Laplace transform technique and separation of variables technique. Based on the obtained solutions, the influence of parameters of pile end soil on the dynamic response is studied in detail for different designing parameters of pile. Lastly, the fictitious soil-pile model and other pile end soil supporting models are compared. It is shown that the dynamic response obtained by the fictitious soil-pile model is among the dynamic responses obtained by other existing models if there are appropriate material parameters and thickness of pile end soil for the fictitious soil-pile model.

  4. Comparison of Design Methods for Axially Loaded Driven Piles in Cohesionless Soil

    DEFF Research Database (Denmark)

    Thomassen, Kristina; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    2012-01-01

    For offshore wind turbines on deeper waters, a jacket sub-structure supported by axially loaded piles is thought to be the most suitable solution. The design method recommended by API and two CPT-based design methods are compared for two uniform sand profiles. The analysis show great difference...... in the predictions of bearing capacities calculated by means of the three methods for piles loaded in both tension and compression. This implies that further analysis of the bearing capacity of axially loaded piles in sand should be conducted....

  5. Field study of plastic tube cast-in-place concrete pile

    Institute of Scientific and Technical Information of China (English)

    陈永辉; 曹德洪; 王新泉; 杜海伟; 张霆

    2008-01-01

    The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on single piles with different forms of pile shoes and on their composite foundations were analyzed. The distribution patterns of axial force, shaft friction and toe resistance were studied based on the measurements taken from buried strain gauges. From the point of engineering application, the pile has merits in convenient quality control, high bearing capacity and reliable quality, showing higher reasonability, advancement and suitability than other ground improvement methods. The pile can be adopted properly to take place of ordinary ground improvement method, achieving greater economical and social benefits.

  6. Non-probabilistic fuzzy reliability analysis of pile foundation stability by interval theory

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Randomness and fuzziness are among the attributes of the influential factors for stability assessment of pile foundation.According to these two characteristics, the triangular fuzzy number analysis approach was introduced to determine the probability-distributed function of mechanical parameters. Then the functional function of reliability analysis was constructed based on the study of bearing mechanism of pile foundation, and the way to calculate interval values of the functional function was developed by using improved interval-truncation approach and operation rules of interval numbers. Afterwards, the non-probabilistic fuzzy reliability analysis method was applied to assessing the pile foundation, from which a method was presented for nonprobabilistic fuzzy reliability analysis of pile foundation stability by interval theory. Finally, the probability distribution curve of nonprobabilistic fuzzy reliability indexes of practical pile foundation was concluded. Its failure possibility is 0.91%, which shows that the pile foundation is stable and reliable.

  7. Slime thickness evaluation of bored piles by electrical resistivity probe

    Science.gov (United States)

    Chun, Ok-Hyun; Yoon, Hyung-Koo; Park, Min-Chul; Lee, Jong-Sub

    2014-09-01

    The bottoms of bored piles are generally stacked with soil particles, both while boreholes are being drilled, and afterward. The stacked soils are called slime, and when loads are applied on the pile, increase the pile settlement. Thus to guarantee the end bearing capacity of bored piles, the slime thickness should be precisely detected. The objective of this study is to suggest a new method for evaluating the slime thickness, using temperature compensated electrical resistivity. Laboratory studies are performed in advance, to estimate and compare the resolution of the electrical resistivity probe (ERP) and time domain reflectometry (TDR). The electrical properties of the ERP and TDR are measured using coaxial type electrodes and parallel type two-wire electrodes, respectively. Penetration tests, conducted in the fully saturated sand-clay mixtures, demonstrate that the ERP produces a better resolution of layer detection than TDR. Thus, field application tests using the ERP with a diameter of 35.7 mm are conducted for the investigation of slime thickness in large diameter bored piles. Field tests show that the slime layers are clearly identified by the ERP: the electrical resistivity dramatically increases at the interface between the slurry and slime layer. The electrical resistivity in the slurry layer inversely correlates with the amount of circulated water. This study suggests that the new electrical resistivity method may be a useful method for the investigation of the slime thickness in bored piles.

  8. THE NEW STRUCTURE OF A PLATE-PILE FOUNDATION

    Directory of Open Access Journals (Sweden)

    SAMORODOV О. V.

    2016-01-01

    Full Text Available Raising of problem. In the construction of high-rise buildings with significant loads on foundations and bedding at the base of not rocky soils tend to use the most common pile foundation to reduce the deformation and correspond to regulations [1] on the maximum permissible deformation. Monitoring of the stress-strain state (SSS pile foundations constructed buildings shows the existing reserves of bearing capacity on the one hand - soil bases of the second group of limit states, on the other - the foundation of the first group of limit states by regulating the SSS foundation during construction and exploitation. Therefore, are increasingly using more progressive structure of foundations consisting of piles and of plate, as well as methods for their construction [2 - 10], however, in their design there are a number of disadvantages associated with the ambiguity of the application of methods for the calculation of such structures, which allows to do only partial conclusions and recommendations. Purpose. Is proposing the new structure of a plate-pile foundation, which overcomes the drawbacks of the existing design solutions and methods of consruction their, as well as is proposing an engineering method of a determination of basic parameters. Conclusion. Is proposes the new structure of a plate-pile foundation and the method of a determination of basic parameters his in the design of a soil base to the maximum permissible deformation Su buildings. Efficiency of application this type plate-pile foundation obtained by rational distribution resistance between a plate and piles, when under load from the building to the first work fully incorporated plate that allows maximum deformed for plate, and then the piles - due to of the hinge connection with the plate. Thus, depending on the maximum permissible deformation for buildings resistance of plate part of a full load of more than 50%, that significantly reduces the consumption of concrete.

  9. Retrofitting Of RCC Piles By Using Basalt Fiber Reinforced Polymer BFRP Composite Part 1 Review Papers On RCC Structures And Piles Retrofitting Works.

    Directory of Open Access Journals (Sweden)

    R. Ananda Kumar

    2015-01-01

    Full Text Available Abstract Retrofitting works are immensely essential for deteriorated and damaged structures in Engineering and Medical fields in order to keep or return to the originality for safe guarding the structures and consumers. In this paper different types of methods of retrofitting review notes are given based on the experimental numerical and analytical methods results on strengthening the Reinforced cement concrete RCC structures including RCC piles. Soil-pile interaction on axial load lateral load reviews are also presented. This review paper is prepared to find out the performance of basalt fibre reinforced polymer BFRP composite retrofitted reinforced cement concrete single end bearing piles.

  10. Adaptação de métodos semi-empíricos para estimar capacidade de carga de estacas de pequeno diâmetro no solo de Londrina, Estado do Paraná = Adaptation of the semi-empiric methods to calculate small diameter piles bearing capacity in the soil of Londrina City, Paraná State

    Directory of Open Access Journals (Sweden)

    Miriam Gonçalves Miguel

    2005-07-01

    Full Text Available A cidade de Londrina, Estado do Paraná, possui um perfil geotécnicoconstituído de uma camada superficial de solo argilo-siltoso, poroso, laterítico e muitas vezes colapsível, que se estende até a profundidade máxima de 12 metros. As estacas utilizadas em obras de pequeno a médio porte se encontram totalmente embutidas nesta camada, sofrendo a influência de seu comportamento laterítico e colapsível. Os métodos clássicos brasileiros de estimativa de capacidade de carga de estacas tornam-se conservadores, frente aos resultados reais, quando aplicados em solos lateríticos e, contra a segurança, quando aplicados em solos colapsíveis, isto é, na condição crítica ao colapso. Este trabalho avalia os coeficientes de ajuste das resistências de ponta e ao atrito lateral para esses métodos, no caso de estacas apiloadas, sendo estes coeficientes obtidos pela retro-análise de resultados de provas de carga estática à compressão, realizadas no Campo Experimental de Engenharia Geotécnica da Universidade Estadual de Londrina.The city of Londrina, Paraná, has a typical geotechnical profile defined by a superficial layer of porous silty clay with maximum depth of about 12 meters, that shows lateritic characteristics, andmany times, collapsibility. Casts in place piles are often used for small buildings in the region and are fully embedded in this soil layer. Therefore, this type of foundation is subjected to the lateritic and occasionally collapsible influence of soil. Brazilian pile bearing capacity methods may yield conservative results when applied to tropical soils, as far as the lateritic origin in concerned. On the other hand, it can be unsafe if collapsibility prevails. This paper evaluates coefficients to adjust both point and lateral resistance of cast in place small diameter piles in the situation described. The work was carried out at the Londrina State University Geotechnical Experimental Site, and back analysis from static

  11. Polar bear use of a persistent food subsidy: insights from non-invasive genetic sampling in Alaska

    Science.gov (United States)

    Peacock, Elizabeth; Herreman, Jason

    2013-01-01

    Remains of bowhead whales (Balaena mysticetus) harvested by Iñupiat whalers are deposited in bone piles along the coast of Alaska and have become persistent and reliable food sources for polar bears (Ursus maritimus). The importance of bone piles to individuals and the population, the patterns of use, and the number, sex, and age of bears using these resources are poorly understood. We implemented barbed-wire hair snaring to obtain genetic identities from bears using the Point Barrow bone pile in winter 2010–11. Eighty-three percent of genotyped samples produced individual and sex identification. We identified 97 bears from 200 samples. Using genetic mark–recapture techniques, we estimated that 228 bears used the bone pile during November to February, which would represent approximately 15% of the Southern Beaufort Sea polar bear subpopulation, if all bears were from this subpopulation. We found that polar bears of all age and sex classes simultaneously used the bone pile. More males than females used the bone pile, and males predominated in February, likely because 1/3 of adult females would be denning during this period. On average, bears spent 10 days at the bone pile (median  =  5 days); the probability that an individual bear remained at the bone pile from week to week was 63% for females and 45% for males. Most bears in the sample were detected visiting the bone pile once or twice. We found some evidence of matrilineal fidelity to the bone pile, but the group of animals visiting the bone pile did not differ genetically from the Southern Beaufort Sea subpopulation, nor did patterns of relatedness. We demonstrate that bowhead whale bone piles may be an influential food subsidy for polar bears in the Barrow region in autumn and winter for all sex and age classes.

  12. Piled Embankment Design Comparison

    Directory of Open Access Journals (Sweden)

    Drusa Marián

    2015-05-01

    Full Text Available There are currently several national standards or regulations for the design of the piled embankment, providing suitable solutions for foundation of transport structure on soft, high compressible subsoil, [1]. The most widely used and the best-known standard is British Standard BS8006 [2], which was confronted with another analytical design methodologies (Ebgeo, CUR. Today’s popularity and versatility of FEM numerical models brings many advantages, which analytical methods cannot achieved, but must be verified by proposed scaled physical model, which was currently being developed by Department of Geotechnics, University of Žilina.

  13. Piled Embankment Design Comparison

    Science.gov (United States)

    Drusa, Marián; Kais, Ladislav; Vlček, Jozef; Mečár, Martin

    2015-05-01

    There are currently several national standards or regulations for the design of the piled embankment, providing suitable solutions for foundation of transport structure on soft, high compressible subsoil, [1]. The most widely used and the best-known standard is British Standard BS8006 [2], which was confronted with another analytical design methodologies (Ebgeo, CUR). Today's popularity and versatility of FEM numerical models brings many advantages, which analytical methods cannot achieved, but must be verified by proposed scaled physical model, which was currently being developed by Department of Geotechnics, University of Žilina.

  14. Determination of load-transfer parameters of single piles axially loaded

    Directory of Open Access Journals (Sweden)

    Yaich Achour N

    2014-04-01

    Full Text Available Modern buildings require more use of the deep foundations including piles. The good perception of the behavior of piles and the knowledge of their bearing capacity is essential for a rational use. The present work focuses on the behavior of single pile under vertical loads in clay and sand soils. Thus, an approach to semi-empirical calculations load transfer as well as finite element modeling are used in order to determine the curve loading / sag at the head of pile and deduce the calculation parameters. This study has allowed predicting the load curves piles, knowing their geometric properties and some test results of in-situ soil (CPT, PMT and SPT.

  15. Numeric simulation analysis of load-settlement relation of pile in layer foundation

    Institute of Scientific and Technical Information of China (English)

    WANG You-qing

    2006-01-01

    Considering the level distribution of soil layers, the soils surrounding pile are simulated with level finite layer elements. Supposing that the vertical deformation of the soil elements surrounding pile varies in the form of exponent function with radial distance, and considering the nonlinear constitutive relation of stress and strain, the stiffness matrix is established. The mechanics behavior of the pile-soil interface is simulated with a nonlinear interface element. This method can truly express the behavior of the pile-soil system. The load-settlement relation Q-S curves of two big diameter prototype piles on bearing test are analyzed, and satisfying results are obtained. This method is reasonable in theory and feasible in engineering.

  16. MODEL TEST STUDY OF STRUCTURAL PROPERTIES OF PILED-RAFT FOUNDATION AFFECTED BY PILE SPACING%桩间距对桩筏基础结构性能影响的模型试验研究

    Institute of Scientific and Technical Information of China (English)

    蒋刚; 江宝; 王旭东; 周峰

    2013-01-01

      为研究桩间距对桩筏基础结构性能的影响,设计并进行不同桩间距的桩筏基础系列模型试验。结果表明,设置不同的桩间距可调配群桩基础中桩与筏板的分担作用,调整桩筏基础的受力性能。常规桩距桩筏基础以桩为承载主体,地基土的荷载分担次之;当桩间距大于6倍桩径后,桩较早进入塑性支承状态,地基土分担荷载能力增强,桩与筏板荷载分担的主次作用发生转换,筏板逐渐转换为基础的承载主体。随着桩间距增大,筏板内力分布由整体弯曲过渡到以局部弯曲为主。桩筏基础桩顶荷载分布规律受桩间距的影响,随着桩间距增大,桩顶荷载由角桩最大逐渐转化为中间桩最大。建议桩筏基础设计方法应考虑桩间距设置对筏板与桩土体系相对刚度、筏板内力和桩顶荷载不均匀特征的影响。%  In order to study the influence of pile spacing on the structural properties of piled-raft foundation, model tests of piled-raft foundation with different pile spacings had been investigated. The results indicate that the effect of loading share ratio between pile and subsoil could be adjusted by different pile spacings. Then the mechanical properties of piled-raft foundation are regulated. The piles are mainly bearing body of piled-raft foundation being in conventional pile spacing,and the subsoil takes the second place. As the pile spacing is over 6 times of pile diameter,the shared-load effect of subsoil increases;piles go at plastically bearing capacity status earlier. Then the raft becomes the main bearing body of piled raft foundation as loading increases. With pile spacing increasing,the internal force distribution properties of raft transfer from wholly bending status to locally bending status. The uneven loading distribution regulation on pile-raft tops is affected by pile spacing. The maximal loading of pile under raft transfers from corner

  17. Laboratory Model Test on Interaction of Pile-tip Soils and Pile-side Soils%灌注桩桩端与桩侧土体相互作用试验研究

    Institute of Scientific and Technical Information of China (English)

    王学知; 李亚东; 赵春风

    2012-01-01

    Based on the laboratory model experiment, according to the influence factors during the pile construction, the bearing condition of the pile-side soils and pile-tip soils is controlled by setting mire skin around the pile and asbestos at the bottom of pile. Then the influence regulation on the pile-tip bearing capacity and pile lateral friction is studied by the change of the condition of the pile-tip soils and pile-side soils respectively. By the experimental study, the commutative enhance mechanism is revealed.%基于室内模型桩试验方法,结合灌注桩施工工艺对桩侧与桩端土体造成的影响,通过在桩侧设置泥皮与在桩端铺设石棉毡的方法分别控制桩侧与桩端土体承载条件,考察桩侧土体性质变化对桩端阻力的影响规律以及桩端土体性质改变时桩侧摩阻力的变化特征,进而揭示灌注桩桩端与桩侧土体相互强化的规律.

  18. Design of Continuous Flight Auger Pile Foundation for a Multi-Storey Apartment Building

    OpenAIRE

    Yatskevich, Yulia

    2010-01-01

    The object of this work was studying, systemizing and describing continuous flight auger (CFA) pile foundation design for a residential complex and calculating the bearing capacity of a single СFA pile on the basis of Russian Building Code. This thesis was written on the request of the YIT Lentek JSK Design Department. The information for the theoretical part was gathered from Russian Building Codes, theoretical manuals, other common available materials (including the Internet), and proje...

  19. STUDY OF SOFT SOIL REINFORCEMENT USING HYBRID PILE-PVD

    OpenAIRE

    Sandyutama, Y.; L.Samang; A. M. Imran; Harianto, T.

    2015-01-01

    Recently due to the high demand of construction road need the construction in short period. The problem of construction on soft clay is the low bearing capacity and total as well as differential settlements. Therefore, innovation in soil improvement is needed. Soft soil improvement by geotextile and rigid piles is an interesting method to provide and economic and effective solution, which reduces settlements, construction time and cost. Full-scale tests were performed to investigate the perfo...

  20. Pile foundation design of complex pile-supported structure integrated with 3D strata model%耦合三维地层模型的复杂高桩结构桩基设计

    Institute of Scientific and Technical Information of China (English)

    刘杰; 芦志强; 杨凯

    2013-01-01

      针对复杂高桩结构桩基设计的空间问题和传统地质资料的表达不足,为信息化、可视化管理桩基,提出了建立桩基信息数据库;基于工程区域的多源地形、地质数据,引入三维地层建模技术,建立了复杂高桩结构的三维地层耦合模型,并实现桩基和地层的三维重建、碰桩检测、桩位优化、持力层的选取、桩长及轴向承载力计算、桩位自动绘制等可视化辅助设计功能,极大提高了复杂高桩结构桩基设计的效率与水平。%  To counter the spatial issues of pile foundation design for complex pile-supported structure and lack expression of traditional geological data, we establish the pile information database for digitally and visually managing piles to facilitate design work. By coupling 3D piles model and strata-graphic model, we achieve several visual-aided design functions, such as reconstruction of piles and strata, collision detection and optimization of piles layout, selection of pile bearing stratum, calculation of pile length and axial bearing capacity, and automatic output of piles layout in 2D. The successful application of the technical solutions has improved the efficiency and level of pile foundation design for complex pile-supported structure.

  1. Viscoelastic behavior of concrete pile

    Institute of Scientific and Technical Information of China (English)

    丁科; 唐小弟

    2008-01-01

    Based on constitutive theory of viscoelasticity,the viscoelastic behaviour of concrete pile was investigated.The influence of viscosity coefficient on the stress,displacement and velocity response was discussed.With the increase of viscosity coefficient,the amplitude of stress wave decreases,and the maximum value of the stress wave shifts to deeper position of the pile.In other words,the viscosity coefficient behaves as lag effect to stress wave.

  2. Target reliability index for serviceability limit state of single piles

    Institute of Scientific and Technical Information of China (English)

    边晓亚; 郑俊杰; 徐志军; 章荣军

    2015-01-01

    The objective is to develop an approach for the determination of the target reliability index for serviceability limit state (SLS) of single piles. This contributes to conducting the SLS reliability-based design (RBD) of piles. Based on a two-parameter, hyperbolic curve-fitting equation describing the load−settlement relation of piles, the SLS model factor is defined. Then, taking into account the uncertainties of load−settlement model, load and bearing capacity of piles, the formula for computing the SLS reliability index (βsls) is obtained using the mean value first order second moment (MVFOSM) method. Meanwhile, the limit state function for conducting the SLS reliability analysis by the Monte Carlo simulation (MCS) method is established. These two methods are finally applied to determine the SLS target reliability index. Herein, the limiting tolerable settlement (slt) is treated as a random variable. For illustration, four load test databases from South Africa are compiled again to conduct reliability analysis and present the recommended target reliability indices. The results indicate that the MVFOSM method overestimatesβsls compared to that computed by the MCS method. Besides, both factor of safety (FS) and slt are key factors influencingβsls, so the combination of FS andβsls is welcome to be used for the SLS reliability analysis of piles when slt is determined. For smaller slt, pile types and soils conditions have significant influence on the SLS target reliability indices; for larger slt, slt is the major factor having influence on the SLS target reliability indices. This proves that slt is the most key parameter for the determination of the SLS target reliability index.

  3. DETERMINING DRIVING RESISTANCE WITH REBOUND OF PILE-TOP DURING PILE DRIVING

    Institute of Scientific and Technical Information of China (English)

    陈仁朋; 胡亚元; 陈云敏

    2001-01-01

    This paper presents a method to determine driving resistance with rebound of pile-top during pile driving. The soil around the pile shaft is assumed to be rigid-plastic, while that under the pile-tip is assumed to be ideally elastoplastic. The driving force acting on the pile-top is simplified to a triangular impact force. The kinematic equation of the pile-tip is established. From the one-dimensional wave equation, the movements of the pile-tip and pile-top are determined. The rebound at the pile-top can be written in a very concise form. It is shown that the shaft resistance makes the rebound at the pile-top decrease. In particular, when the pile is very long or the soil around the pile is very stiff, the decrease is very obvious.

  4. Simulation analysis for O-cell test of pile and the interaction of upper pile and lower pile

    Institute of Scientific and Technical Information of China (English)

    ZHENG Ying-jie; ZHANG Ke-xu; ZHANG Er-qi

    2009-01-01

    In this paper, the soil-pile system of O-cell test of pile is simplified as an axi-symmetrie problem.By using aggregation of quadrilateral isoparametrie elements to simulate pile and soil, setting Goodman' s elements between pile and soils, a method of numerical simulation analysis on O-cell test of pile is presented with the consideration of nonlinear mechanical behavior of soils and pile-soil interface.The method is applied to the a-nalysis of a case of O-cell test of pile.The load-displacement curves and axial force curves of upper pile and lower pile obtained from the O-cell test of pile are fitted, and parameters of the mechanical model of soils and interface are determined.Analysis results validate that the numerical simulation analysis method put forward in this paper is applicable.Furthermore, the interaction and influence of upper pile and lower pile in the O-cell test are also studied with the method.The result shows that if load box is located in a soil layer with fine me-chanical behavior, the interaction of upper pile and lower pile in O-cell test can be ignored generally.

  5. 十字形沉管灌注桩的成桩工艺技术%Pile-formed technology for cross tube-sinking cast-in-place pile

    Institute of Scientific and Technical Information of China (English)

    邹正盛; 孔清华; 莫云波; 孔红斌

    2012-01-01

    The change of pile cross section can increase the lateral area of pile, and pile bearing capacity can be improved. Based on this, the piles with abnormal section were developed. At present, a variety of special-shaped section piles on which research or application is more, such as X and Y pile, are formed by the casing with uniform section and tube-sinking method in China. Because the deformation resistance capability of these casings is weak, application of these casings on construction of long piles or super-long piles is limited. The casing for the cross shaped pile is the circular steel casing with bottom wings, and has strong resistance to deformation. So, it can be used in construction of big piles, long piles or super-long piles, concrete or reinforced concrete piles, soil-squeezing piles and soil-borrowing piles, which can be used for foundation treatment, and also for construction of the foundation piles. When the special soil-borrowing devices are used for non soil-squeezing piles, quick construction, high efficient pile-forming and low cost can be able to realize.%改变桩截面形状,增加桩周面积,可提高桩承载力,因此导致了异形截面桩的诞生.目前我国研究较多的多种异形截面桩如X桩、Y桩等,均是采用全长等截面的异形截面模管沉管成桩.由于这些异形截面模管抗变形能力相对较弱,在应用到长桩或超长桩的施工上可能会受到一定的限制.十字形桩成桩模管为底部加翼的圆形截面钢模管,抗变形能力强,能成大桩长桩或超长桩、混凝土素桩或钢筋混凝土桩、挤土桩或非挤土桩,既可用于地基处理,也可作为基桩施工.非挤土桩成桩时,采用专用管内取土装置,施工快捷,成桩效率高,成本低.

  6. Analysis of Interaction Factors Between Two Piles

    Institute of Scientific and Technical Information of China (English)

    CAO Ming; CHEN Long-zhu

    2008-01-01

    A rigorous analytical method is presented for calculating the interaction factor between two identical piles subjected to vertical loads. Following the technique proposed by Muki and Sternberg, the problem is decomposed into an extended soil mass and two fictitious piles characterized respectively by Young's modulus of the soil and that of the difference between the pile and soil. The unknown axial forces along fictitious piles are determined by solving a Fredholm integral equation of the second kind, which imposes the compatibility condition that the axial strains of the fictitious piles are equal to those corresponding to the centroidal axes of the extended soil. The real pile forces and displacements can subequally be calculated based on the determined fictitious pile forces, and finally, the desired pile interaction factors may be obtained. Results confirm the validity of the proposed approach and portray the influence of the governing parameters on the pile interaction.

  7. Comparison on the Horizontal Behaviors of Lattice-Shaped Diaphragm Wall and Pile Group under Static and Seismic Loads

    Directory of Open Access Journals (Sweden)

    Jiu-jiang Wu

    2016-01-01

    Full Text Available Lattice-shaped diaphragm wall (hereafter referring to LSDW is a new type of bridge foundation, and the relevant investigation on its horizontal behaviors is scant. This paper is devoted to the numerical study of the comparison on the static and seismic responses of LSDW and pile group under similar material quantity in soft soil. It can be found that the horizontal bearing capacity of LSDW is considerably larger than that of pile group, and the deformation pattern of LSDW basically appears to be an overall toppling while pile group clearly shows a local bending deformation pattern during the static loading process. The acceleration response and the acceleration amplification effects of LSDW are slightly greater than that of pile group due to the existing of soil core and the difference on the ability of energy dissipation. The horizontal displacement response of pile group is close to that of LSDW at first and becomes stronger than that of LSDW due to the generation of plastic soil deformation near the pile-soil interface at last. The pile body may be broken in larger potential than LSDW especially when its horizontal displacement is notable. Compared with pile group, LSDW can be a good option for being served as a lateral bearing or an earthquake-proof foundation in soft soil.

  8. A new method for testing pile by single-impact energy and P-S curve

    Science.gov (United States)

    Xu, Zhao-Yong; Duan, Yong-Kang; Wang, Bin; Hu, Yi-Li; Yang, Run-Hai; Xu, Jun; Zhao, Jin-Ming

    2004-11-01

    By studying the pile-formula and stress-wave methods ( e.g., CASE method), the authors propose a new method for testing piles using the single-impact energy and P-S curves. The vibration and wave figures are recorded, and the dynamic and static displacements are measured by different transducers near the top of piles when the pile is impacted by a heavy hammer or micro-rocket. By observing the transformation coefficient of driving energy (total energy), the consumed energy of wave motion and vibration and so on, the vertical bearing capacity for single pile is measured and calculated. Then, using the vibration wave diagram, the dynamic relation curves between the force ( P) and the displacement ( S) is calculated and the yield points are determined. Using the static-loading test, the dynamic results are checked and the relative constants of dynamic-static P-S curves are determined. Then the subsidence quantity corresponding to the bearing capacity is determined. Moreover, the shaped quality of the pile body can be judged from the formation of P-S curves.

  9. Instrumented model pile tests on sand plugs

    Energy Technology Data Exchange (ETDEWEB)

    Haaren, L.J.C. van; Verruijt, A. [Delft Univ. of Technology (Netherlands); Kolk, H.J. [Fugro Engineers B.V., Leidschendam (Netherlands)

    1995-12-31

    0pen ended piles develop internal frictional resistance between the internal soil plug end the pile wall during axial loading. Current pipe pile design practice assumes that the ultimate internal skin friction is of the same order of magnitude as the outer skin friction. This paper describes a series of laboratory pile load tests on instrumented model pipe piles, designed to investigate the development of plug stresses and skin friction along the plug length during pile loading. The piles contain sand columns of various relative densities and of different heights. The soil plugs are loaded to failure under fully drained conditions. The test data indicate that internal skin friction in sand can be substantially higher than assumed in conventional design practice. This finding could lead to significant economical savings on future pipe pile foundations in sand.

  10. Displacement and deformation analysis for uplift piles

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    On the assumptions that the shear resistance increases linearly with increasing shear displacement between the uplift pile and surrounding soil,that the axis force is distributed as parabola along the pile length,that elastic distortion occurs when the pile is loaded,that the displacement of pile is in accord with that of the soil,and that the uplift pile failure is regarded as the soil failure,arational calculation method was proposed for calculating the deformation,ultimate displacement and shear resistance of piles.The distributions of frictional resistance and the shear displacement along the pile length were obtained with the method.The comparisons were made between the measurement results and the present results.The present theoretical results agree well with the measurement results,with the average difference being less than 12% before failure.The comparisons show that the proposed method is reasonable for uplift design and engineering construction of piles.

  11. Experiment and Analysis of the Pile-bottom Grouting Technology in Ming River Aqueduct Pile Foundation%桩底压浆技术在洺河渡槽桩基试验与分析

    Institute of Scientific and Technical Information of China (English)

    杨镇生

    2013-01-01

      洺河渡槽通过3根试验桩的桩底压浆前后静载对比试验,测定桩底压浆对桩周侧摩阻力和端承力的增强效果,为桩底压浆提供设计计算参数和施工工艺参数。%Through the static load comparative tests before and after pile-bottom grouting of three test piles in Ming River aqueduct, determining the effect of the pile bottom grouting on pile side friction resistance and end bearing capacity, pro-viding the design calculation parameters and construction process parameters for the pile bottom grouting.

  12. Influence of vertical loads on lateral pile group response considering soil-pile-cap interactions

    Science.gov (United States)

    Hussien, Mahmoud N.; Tobita, Tetsuo; Iai, Susumu

    This paper presents the results of a numerical investigation conducted to study the effect of vertical loads on lateral response of a free head and a capped pile group in sand. A coupled soil-pile system is idealized through 2D finite elements with soil models idealized by a hyperbolic type multiple shear mechanism. The analysis focuses on the five piles in the middle row of a 3x5 pile group spaced at 3.92-pile diameters. The interaction between a pile and the surrounding soil in the 3D type is idealized in the 2D analysis using soil-pile interaction springs with a hysteretic non-linear load displacement relationship. The presence of vertical loads on free head piles increases the confining pressures in the sand deposit confined by the piles but the rate of increase in those outside the group is relatively small, resulting in the difference in a balance of lateral soil pressures acting at the back of and in front of individual piles. A vertical load applied to a group pile with a uniform vertical displacement of 0.1 pile diameter decreases the lateral resistance of the leading pile (pile 1) by 10 % and increases the lateral resistance of piles 3 and 5 by 14 and 35 %, respectively. The same trend with higher percentages of increase or decrease is observed in the capped pile group case.

  13. Bearing system

    Science.gov (United States)

    Kapich, Davorin D.

    1987-01-01

    A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

  14. OF THE SLAB-PILE FOUNDATION

    Directory of Open Access Journals (Sweden)

    Ter-Martirosyan ZavenGrigorevich

    2012-10-01

    It is proven that the above properties produce a substantial impact onto the stress-strain state of soils that interact with the pile and the grid, and the impact values make it possible to assess the rigidity of the slab-pile foundation that is needed to solve the problems of the multiplicity of piles as well as the problems of distribution of the total load between the piles and the grid.

  15. Analysis of pile foundations under dynamic loads

    International Nuclear Information System (INIS)

    A method is presented for the analysis of pile foundations which are subjected to horizontal dynamic loads from earthquakes, airplane impact, gas explosion or other sources. The motion of the pile cap and the pile forces are computed. - The loads may be applied to the pile cap or directly to the piles (e.g. by earthquake wave motion). The soil may be stratified and is considered to be an elastic or visco-elastic medium. The piles are assumed vertical. The method makes use of an approximate fundamental solution for displacements caused by a dynamic point load in a layered visco-elastic medium. The approximation involves a discretization of the medium in the vertical direction. In horizontal directions the medium is treated by continuum theory. The soil medium supports each pile at about 10 to 20 nodes. A dynamic flexiblity matrix for the soil is derived which relates the elastic, damping and inertial forces of the soil to the displacements at each node. It includes effects of radiation damping. All piles are coupled through the soil flexibility matrix. The piles are modelled by beam elements. Transient response is computed using fast discrete Fourier transforms. The arrangement of the piles is arbitrary. However, simple and double symmetry can be accounted for by the computer program. When the pile arrangement is axisymmetric, the degrees of freedom can be reduced to only those of two piles per ring. The influence of the number of piles and the influence of the pile spacing on group stiffness and on pile forces is presented for two soil profiles. Dynamic effects on pile forces of a foundation for a reactor building are studied. They are significant when soils are soft. (orig.)

  16. APPLICATION OF STEEL PIPE PILE LOADING TESTS TO DESIGN VERIFICATION OF FOUNDATION OF THE TOKYO GATE BRIDGE

    Science.gov (United States)

    Saitou, Yutaka; Kikuchi, Yoshiaki; Kusakabe, Osamu; Kiyomiya, Osamu; Yoneyama, Haruo; Kawakami, Taiji

    Steel sheet pipe pile foundations with large diameter steel pipe sheet pile were used for the foundation of the main pier of the Tokyo Gateway bridge. However, as for the large diameter steel pipe pile, the bearing mechanism including a pile tip plugging effect is still unclear due to lack of the practical examinations even though loading tests are performed on Trans-Tokyo Bay Highway. In the light of the foregoing problems, static pile loading tests both vertical and horizontal directions, a dynamic loading test, and cone penetration tests we re conducted for determining proper design parameters of the ground for the foundations. Design parameters were determined rationally based on the tests results. Rational design verification was obtained from this research.

  17. CONDUCTING AND ANALYZING THE RESULTS OF THE EXPERIMENTAL BOX TEST OF RETAINING WALL MODELS WITHOUT PILES AND ON THE PILE FOUNDATION

    Directory of Open Access Journals (Sweden)

    M. A. Lisnevskyi

    2015-08-01

    Full Text Available Purpose. Taking into consideration that the bearing capacity of the foundation may be insufficient, in the study it is assumed that pile foundation can be used to reduce the impact of the construction of new retaining structures on roads and railways near the existing buildings or in areas of dense urban development and ensure the stability of the foundation. To reduce the volume of excavation it is necessary to choose the economic structure of the retaining wall. To do this, one should explore stress-strain state (SSS of the retaining walls, to develop methods to improve their strength and stability, as well as to choose the most appropriate method of their analysis. Methodology. In the design of retaining walls foundation mat and piles are considered as independent elements. Since the combined effect of the retaining wall, piles and foundation mat as well as the effect of soil or rock foundation on the structure are considered not fully, so there are some limitations in the existing design techniques. To achieve the purpose the box tests of retaining walls models without piles and with piles for studying their interaction with the surrounding soil massif were conducted. Findings. Laboratory simulation of complex systems «surrounding soil – retaining wall – pile» was carried out and on the basis of the box test results were analyzed strains and its main parameters of the stress-strain state. Analysis of the results showed that the structure of a retaining wall with piles is steady and stable. Originality. So far, in Ukraine has not been carried out similar experimental box tests with models of retaining walls in such combinations. In the article has been presented unique photos and test results, as well as their analysis. Practical value. Using the methodology of experimental tests of the retaining wall models with piles and without them gives a wider opportunity to study stress-strain state of such structures.

  18. 桩土共同作用原理在处理质量事故方面的应用%The Principle of Pile-soil Interaction Applied to Reinforce Pile Accident

    Institute of Scientific and Technical Information of China (English)

    朱奎; 徐日庆; 沈加珍

    2011-01-01

    某工程桩出现质量事故,根据承载力和地质情况对桩基特点进行了分析,利用桩土共同作用原理进行加固,通过土参与承载补偿桩承载力不足.在构造上将基础与桩脱开,并设置褥垫层,通过有效技术措施促使桩土变形协调,从而达到桩土共同作用的效果.工程实例表明承载力和沉降均可以满足要求.%Quality accident of pile happened, and the character of pile foundation is analyzed according to the geological condition and beadng capacity. The reinforcements which based on the principle of pile-soil interaction is adopted,soil supported load to compensate inadequate bearing capacity of pile. foundation and pile is separated in structure and cushion is applied,and the effective technical measure urge pile-soil distortion coordinate,then pile-soil interaction is achieved, furthermore,engineering project hold that foundation of bearing capacity and settlement can meet with the requirement.

  19. Decommissioning of Windscale pile 1

    International Nuclear Information System (INIS)

    The Windscale Piles were constructed in the late 1940's primarily for the production of plutonium in support of the British atomic weapons programme. In 1957 Pile 1 suffered a fire during the routine release of stored Wigner energy by nuclear heating. Following the fire as much material as possible was recovered, an inventory and status report prepared and the pile sealed and placed under surveillance and maintenance, the only practicable option at the time. Over the last decade in addition to general improvements in routine monitoring equipment there has been extensive investigative work carried out to better understand the damage caused by the fire and assess the options for further action. These studies concluded that the preferred option was for the Pile core to be removed, treated and packaged for intermediate storage prior to final disposal. The paper will describe the core investigations, the assessed conditions, and the options considered. It will also describe the tendering process to allow contractors to propose solutions against a cardinal point specification, the outline of the preferred solution and the progress of the work to date. (author)

  20. DRIVEN POLYSTRONG REINFORCED CONCRETE PILES AND NEW DESIGN OF PILE CAPS

    Directory of Open Access Journals (Sweden)

    I. I. Bekbasarov

    2015-01-01

    Full Text Available The paper presents constructional and technological features for manufacturing driven piles with variable strength of pile shaft. Economical efficiency of their production has been shown in the paper. The paper provides a pile cap design that ensures perception of hammer impacts with the help of lateral edges of the pile cap. Driven reinforced concrete piles which are manufactured from three shaft sections having various strength have been proposed in the paper. Material strength (concrete grade and diameter of bars and length of shaft sections are given on a case by case basis in accordance with nature and rate of stresses in piles during their driving process. Manufacturing of polystrong piles provides an opportunity to select them for a particular construction site with due account of their preservation during driving process.A pile cap has been developed that as opposed to existing analogous designs makes it possible to transmit impact efforts from a hammer to the pile through lateral surface of its head part. The pile cap provides the possibility to increase an area for perception of hammer impact efforts by the pile and in doing so it is possible significantly to reduce a damage risk and destruction of pile concrete during its driving. Application of polystrong piles and their driving with the help of new pile cap are considered as a basis for defect-free and resource-saving technology for pile foundations in the construction.

  1. Pullout capacity of batter pile in sand.

    Science.gov (United States)

    Nazir, Ashraf; Nasr, Ahmed

    2013-03-01

    Many offshore structures are subjected to overturning moments due to wind load, wave pressure, and ship impacts. Also most of retaining walls are subjected to horizontal forces and bending moments, these forces are due to earth pressure. For foundations in such structures, usually a combination of vertical and batter piles is used. Little information is available in the literature about estimating the capacity of piles under uplift. In cases where these supporting piles are not vertical, the behavior under axial pullout is not well established. In order to delineate the significant variables affecting the ultimate uplift shaft resistance of batter pile in dry sand, a testing program comprising 62 pullout tests was conducted. The tests are conducted on model steel pile installed in loose, medium, and dense sand to an embedded depth ratio, L/d, vary from 7.5 to 30 and with various batter angles of 0°, 10°, 20°, and 30°. Results indicate that the pullout capacity of a batter pile constructed in dense and/or medium density sand increases with the increase of batter angle attains maximum value and then decreases, the maximum value of Pα occurs at batter angle approximately equal to 20°, and it is about 21-31% more than the vertical pile capacity, while the pullout capacity for batter pile that constructed in loose sand decreases with the increase of pile inclination. The results also indicated that the circular pile is more resistant to pullout forces than the square and rectangular pile shape. The rough model piles tested is experienced 18-75% increase in capacity compared with the smooth model piles. The suggested relations for the pullout capacity of batter pile regarding the vertical pile capacity are well predicted.

  2. Pullout capacity of batter pile in sand

    Directory of Open Access Journals (Sweden)

    Ashraf Nazir

    2013-03-01

    Full Text Available Many offshore structures are subjected to overturning moments due to wind load, wave pressure, and ship impacts. Also most of retaining walls are subjected to horizontal forces and bending moments, these forces are due to earth pressure. For foundations in such structures, usually a combination of vertical and batter piles is used. Little information is available in the literature about estimating the capacity of piles under uplift. In cases where these supporting piles are not vertical, the behavior under axial pullout is not well established. In order to delineate the significant variables affecting the ultimate uplift shaft resistance of batter pile in dry sand, a testing program comprising 62 pullout tests was conducted. The tests are conducted on model steel pile installed in loose, medium, and dense sand to an embedded depth ratio, L/d, vary from 7.5 to 30 and with various batter angles of 0°, 10°, 20°, and 30°. Results indicate that the pullout capacity of a batter pile constructed in dense and/or medium density sand increases with the increase of batter angle attains maximum value and then decreases, the maximum value of Pα occurs at batter angle approximately equal to 20°, and it is about 21–31% more than the vertical pile capacity, while the pullout capacity for batter pile that constructed in loose sand decreases with the increase of pile inclination. The results also indicated that the circular pile is more resistant to pullout forces than the square and rectangular pile shape. The rough model piles tested is experienced 18–75% increase in capacity compared with the smooth model piles. The suggested relations for the pullout capacity of batter pile regarding the vertical pile capacity are well predicted.

  3. High capacity cast-in-place concrete pile load tests at CNRL's oil sand plant near Fort McMurray, Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Clementino, R.; Tweedie, R.; Sobkowicz, J.; Workman, C. [Thurber Engineering Ltd., Calgary, AB (Canada); Sisson, R. [Canadian Natural Resources Ltd., Calgary, AB (Canada)

    2006-07-01

    In order to assess capacities for design of foundation piles, a thorough pile load test program was conducted in 2003 and 2004 at Canadian Natural Resources Limited's (CNRL) Horizon Oil Sands Plant site, located near Fort McMurray, Alberta. One of its major components is a large plant for the extraction and upgrading of bitumen from oil sand. The program consisted of five piles tested in a static frame to vertical loads of up to 10 MN, four piles tested using the statnamic method to loads of up to 16 MN, and two piles tested using Osterberg Cells at equivalent top-down loads of up to 22 MN. This paper described the installation and instrumentation of the piles and presented the test results. It also compared these results to historical design values and discussed the results. It was concluded that the pile load test program demonstrated that high capacity can be achieved with straight shaft piles that extend 6 metres or more into oil sands, with small settlements. Piles may be designed using a combination of shaft friction and end bearing capacity. In many instances, end bearing capacity can be ignored, requiring less base preparation and inspection. 6 refs., 2 tabs., 11 figs.

  4. Pile Load Capacity – Calculation Methods

    Directory of Open Access Journals (Sweden)

    Wrana Bogumił

    2015-12-01

    Full Text Available The article is a review of the current problems of the foundation pile capacity calculations. The article considers the main principles of pile capacity calculations presented in Eurocode 7 and other methods with adequate explanations. Two main methods are presented: α – method used to calculate the short-term load capacity of piles in cohesive soils and β – method used to calculate the long-term load capacity of piles in both cohesive and cohesionless soils. Moreover, methods based on cone CPTu result are presented as well as the pile capacity problem based on static tests.

  5. Erective Sea Embankment with PCC Piles

    Institute of Scientific and Technical Information of China (English)

    LIU Han-long; FEI Kang; DENG An; ZHANG Ting

    2005-01-01

    The sea embankment is a critical civil works in marine and coastal engineering. In this study, an innovative technique is proposed for constructing erective sea embankments. In the construction of sea embankments, this technique integrates PCC pile installation, PVDs drainage systems, and geotextile reinforcements, resulting in sea embankments with PCC piles. In the application of a sea embankment with PCC piles, PCC piles are employed as the retaining structures;the soft sea ground inside PCC piles is drained and improved by PVDs and vacuum-surcharge combined preloading; geotextile-reinforced backfills lying over the improved soft ground form the embankment body. Brief descrptions of the fundamentals, design and construction of the sea embankment with PCC piles are presented. A case study on the stability of sea embankment with PCC piles is presented as well.

  6. Introduction to Single Piles under Lateral Loading

    DEFF Research Database (Denmark)

    Augustesen, Anders; Ibsen, Lars Bo

    The purpose of this chapter is to give a short introduction to single piles subjected to lateral loading. First, the observed behaviour of laterally loaded piles is described, i.e. the effects of loading conditions, installation procedure, pile type etc. on pile behaviour are presented (section 1.......2). The description is based on results of laboratory tests, full-scale field tests as well as numerical investigations presented in literature. Second, general methods that attempt to model lateral pile response are discussed in section 1.4. Third, focus is paid to a widely used method for prediction of the response...... of a lateral loaded pile, namely the Winkler approach in which the pile is modelled as an elastic beam on an elastic foundation (section 1.5). The soil response and thereby the elastic foundation is represented by springs with nonlinear behaviour (p-y curves). In section 1.6 different types and formulations...

  7. Behaviour of jacked and driven piles in sandy soil

    OpenAIRE

    Yang, J; Tham, LG; Lee, PKK; Chan, ST; Yu, F.

    2006-01-01

    As an alternative to conventional dynamic pile installation methods, pile jacking is an environmentally friendly technique that could become more widely accepted. Great concern has arisen over the performance of jacked piles as compared with that of driven piles. This paper describes a comprehensive field study that was aimed at investigating the differences and similarities between the behaviour of jacked H-piles and that of driven H-piles. The instrumented piles, varying in length from 32 t...

  8. Physical modelling of pipe piles under oblique pullout loads using transparent soil and particle image velocimetry

    Institute of Scientific and Technical Information of China (English)

    曹兆虎; 刘汉龙; 孔纲强; 周航

    2015-01-01

    A small-scale physical modelling method was developed to investigate the pile bearing capacity and the soil displacement around the pile using transparent soil and particle image velocimetry(PIV) technique. Transparent sand was made of baked quartz and a pore fluid with a matching refractive index. The physical modelling system consists of a loading system, a laser light, a CCD camera, an optical platform and a computer for image analyzing. A distinctive laser speckle was generated by the interaction between the laser light and transparent soil. Two laser speckle images before and after deformation were used to calculate the soil displacement field using PIV. Two pipe piles with different diameters under oblique pullout loads at angles of 0°, 30°, 45°, 60° and 90° were used in tests. The load-displacement response, oblique pullout ultimate resistances and soil displacement fields were then studied. The test results show that the developed physical modelling method and transparent soil are suitable for pile-soil interaction problems. The soil displacements around the pipe piles will improve the understanding on the capacity of pipe piles under oblique pullout loads.

  9. Mathematical Model and Analysis of Negative Skin Friction of Pile Group in Consolidating Soil

    Directory of Open Access Journals (Sweden)

    Gangqiang Kong

    2013-01-01

    Full Text Available In order to calculate negative skin friction (NSF of pile group embedded in a consolidating soil, the dragload calculating formulas of single pile were established by considering Davis one-dimensional nonlinear consolidation soils settlement and hyperbolic load-transfer of pile-soil interface. Based on effective influence area theory, a simple semiempirical mathematical model of analysis for predicting the group effect of pile group under dragload was described. The accuracy and reliability of mathematical models built in this paper were verified by practical engineering comparative analysis. Case studies were studied, and the prediction values were found to be in good agreement with those of measured values. Then, the influences factors, such as, soil consolidation degree, the initial volume compressibility coefficient, and the stiffness of bearing soil, were analyzed and discussed. The results show that the mathematical models considering nonlinear soil consolidation and group effect can reflect the practical NSF of pile group effectively and accurately. The results of this paper can provide reference for practical pile group embedded in consolidating soil under NSF design and calculation.

  10. Uranium migration and retention during weathering of a granitic waste rock pile

    International Nuclear Information System (INIS)

    Highlights: • We investigate the environmental impact of the granitic waste rock piles. • The majority of the waste rocks in the pile is barren- or overburden rock. • The main neo-formed U-bearing phases are (Ca) and (Cu) uranyl phosphates. • Under circum-neutral pH conditions they do not pose an environment threat. - Abstract: This study investigates the post-mining evolution of S-type granitic waste rocks around a former uranium mine, Vieilles Sagnes (Haute Vienne, NW Massif Central, France). This mine was operated between 1957 and 1965 in the La Crouzille former world-class uranium mining district and is representative of intra-granitic vein-type deposits. 50 years after mine closure and the construction and subsequent re-vegetation of the granitic waste rock pile, we evaluate the environmental evolution of the rock pile, including rock alteration, neo-formation of U-bearing phases during weathering, and U migration. Vertical trenches have been excavated through the rock pile down to an underlying paleo-soil, allowing the investigation of the vertical differentiation of the rock pile and its influence on water pathways, weathering processes and U migration and retention. Arenization dominantly drives liberation of U, by dissolution of uraninite inclusions in the most alterable granitic minerals (i.e. K-feldspar and biotite). Retention of U in the matrix at the base of the waste rock pile, and in the underlying paleo-soil most likely occurs by precipitation of (nano-) uranyl phosphates or a combination of co-precipitation and adsorption reactions of U onto Fe (oxy)hydroxides and/or clay minerals. Even though U-migration was observed, U is retained in stable secondary mineral phases, provided the current conditions will not be modified

  11. Literature review Quasi-static and Dynamic pile load tests: Primarily report on non-static pile load tests

    OpenAIRE

    Huy, N.Q.

    2010-01-01

    Pile testing, which plays an importance role in the field of deep foundation design, is performed by static and non-static methods to provide information about the following issues: (Poulos, 1998) - The ultimate capacity of a single pile. - The load-displacement behavior of a pile. - The performance of a pile during the test conditions. - The integrity of a pile (pile integrity test). For the purposes of verification the design axial capacity and the static load – settlement behavior of piles...

  12. 桩伴侣与基桩抗震的概念设计%Pile Partner and the Conceptual Earthquake-resistant Design of Foundation Pile

    Institute of Scientific and Technical Information of China (English)

    薛江炜; 葛忻声; 蔡景珞; 杨勇

    2013-01-01

    It is uncertain that the lateral components such as basement wall and cap side wall bearing horizontal load,so the conventional pile foundation with low cap might endure lateral force that is larger,and even cause its damage.The applying of pile partner to improve traditional foundation pile structure form is put for ward,especially when there is few frictional force between pile cap and soil,or the soil modulus is small.The partner can be component for anti-earthquake concept design under rare earthquake action,pile partner may be sacrificed firstly to keep pile perform well.The improper design of composite foundation will destroy or weaken the isolation effect of pillow,and can be solved by reserving buffer space between pile and partner.%地下室外墙、承台侧壁等侧向构件承担水平荷载具有很大的不确定性,常规采用的低承台桩基有可能承受较大的甚至导致破坏的水平力,建议用桩伴侣改善传统基桩的构造形式,特别是对于承台与桩间土摩擦力小或者桩身范围地基土模量低的两类状况.在罕遇地震时,作为抗震概念设计的耗能构件,首先牺牲伴侣,避免或延迟桩头的破坏;复合地基如果设计不当会破坏或削弱褥垫层隔震的效果,可在伴侣与桩之间预留缓冲空间.

  13. Thermal Conductivity Of Rubble Piles

    CERN Document Server

    Luan, Jing

    2015-01-01

    Rubble piles are a common feature of solar system bodies. They are composed of monolithic elements of ice or rock bound by gravity. Voids occupy a significant fraction of the volume of a rubble pile. They can exist up to pressure $P\\approx \\epsy\\mu$, where $\\epsy$ is the monolithic material's yield strain and $\\mu$ its rigidity. At low $P$, contacts between neighboring elements are confined to a small fraction of their surface areas. As a result, the effective thermal conductivity of a rubble pile, $\\kcon\\approx k(P/(\\epsy\\mu))^{1/2}$, can be orders of magnitude smaller than, $k$, the thermal conductivity of its monolithic elements. In a fluid-free environment, only radiation can transfer energy across voids. It contributes an additional component, $\\krad=16\\ell\\sigma T^3/3$, to the total effective conductivity, $\\keff=\\kcon +\\krad$. Here $\\ell$, the inverse of the opacity per unit volume, is of order the size of the elements and voids. An important distinction between $\\kcon$ and $\\krad$ is that the former i...

  14. Test Setup for Axially Loaded Piles in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina

    The test setup for testing axially static and cyclic loaded piles in sand is described in the following. The purpose for the tests is to examine the tensile capacity of axially loaded piles in dense fully saturated sand. The pile dimensions are chosen to resemble full scale dimension of piles used...... in offshore pile foundations today....

  15. 斜向荷载作用下桩群中设置斜桩对其沉降的影响分析%Effect analysis of battered pile on the settlement of pile group under inclined loadings

    Institute of Scientific and Technical Information of China (English)

    杨阳; 王国才; 金菲力

    2012-01-01

    The setting mode of pile group has much effect on pile group's bearing capacity and settlement under inclined loadings. In order to reveal this effect, the nonlinear finite element software is used and a 3-D model is developed to simulate the battered pile group under inclined loadings. The effect of inclined angle, pile-soil elastic modulus, battered pile length and number, etc. , on the settlement of battered pile group, is analyzed. The results indicate that: the geometry of soil, the inclined angle of battered pile, pile rigidity, length and number, etc. , has much effect on the settlement of battered pile group. Some useful conclusions are obtained for the design and construction of pile group that subjected to inclined loadings.%斜向荷载作用下桩群的设置方式对其承载力和沉降有较大影响.为揭示这一影响规律,采用非线性有限元软件对斜向荷载作用下桩群中设置的斜桩进行三维建模,分析了斜桩的倾角、桩-土弹性模量、斜桩桩长以及桩数等因素对群桩沉降的影响.结果表明:地基土质情况、斜桩的倾角、刚度和桩长与桩数等对倾斜群桩的沉降影响较大,所得结论对斜向荷载作用下群桩基础的设计与施工具有一定的指导意义.

  16. Numerical Modeling of Laterally Loaded Piles

    OpenAIRE

    S. T. Kok; B. B.k. Huat

    2008-01-01

    Design of laterally loaded piles due to soil movement relies on a number of theoretical and numerical approaches. However, the magnitude of soil movement is difficult to estimate with reasonable confidence and accuracy. Finite Element Analysis (FEA) offers an excellent alternative to study pile-soil interaction and piles response under lateral loading due to soil movement. This research presents published analytical results and case history modeled in a 2D finite element environment in the ca...

  17. Global and local scour at pile groups

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Bundgaard, Klavs; Fredsøe, Jørgen

    2005-01-01

    This paper presents the results of an experimental investigation on scour around pile groups with different configurations exposed to steady current. Two kinds of tests were carried out: rigid-bed tests and actual scour tests. In these, the mean and turbulence properties of the flow were measured...... across the pile groups. The pile-group configurations were such that the global scour was distinguished from the local scour. The results show that the global scour can be quite substantial....

  18. Global and local scour at pile groups

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Bundgaard, Klavs; Fredsøe, Jørgen

    2005-01-01

    This paper presents the results of an experimental investigation on scour around pile groups with different configurations exposed to steady current. Two kinds of tests were carried out: (1) Rigid-bed tests, and (2) Actual scour tests. In the former tests, the mean and turbulence properties...... of the flow were measured across the pile groups. The pile group configurations were such that the global scour was distinguished from the local scour. The results show that the global scour can be quite substantial....

  19. Pile Spacing Optimization of Short Piled Raft Foundation System for Obtaining Minimum Settlement on Peat

    Science.gov (United States)

    Suro, S. M.; Bakar, I.; Sulaeman, A.

    2016-07-01

    Short Piled Raft is a modified piled raft foundation system, which represents combination between raft foundation and pile foundation, but the length of pile is relatively shorter. The basic concept of the Short Piled Raft foundation system considers the passive soil pressure creating a stiff condition of slab-pile system. This means that the thin concrete slab floats on the supporting soil, while the piles serve as stiffeners concrete slab and also to reduce settlement of the foundation. Slab to pile ratio of such system has been mentioned by several researchers, however the optimum pile spacing of stability performance for obtaining minimum settlement on peat haven't been clearly discussed. In this study, finite element method to simulate the stability performance related to settlement of Short Piled Raft foundation system was used. Short Piled Raft foundation system with concrete slab of 7.0 m x 7.0 m square was assumed to be built on peat with the thickness of 3.5 m. The material properties of pile and raft were constant. The outer diameter of galvanized steel pipe as pile was 0.30 m; raft thickness was considered to be constant of 0.15 m and the length of pile was 3.0 m, while the pile spacing varied from 0.50 to 3.00 m. Point load varied from 0 to 100 kN with increment of 20 kN was also considered as a static load, acted on the centre of the concrete slab. Optimization was done by comparing each numerical result of simulations, thus conclusion can easily be drawn. The optimum pile spacing was 1.00 m which produced minimum settlement of 30.11 mm under the load of 100 kN.

  20. Soil stress field around driven piles

    OpenAIRE

    Allard, Marie-Agnes

    1989-01-01

    The description, equipment, and results of a series of pile-driving experiments conducted in a centrifuge using a model pile driven in dry sand are presented. The work was conceived on the basis of the modelling of a soil-structure system under an artificially generated gravitational field, and motivated by the need for experimental data for a better understanding of the complex phenomena involved in the pile-soil interaction during driving. The behavior of the pile itself has been the fo...

  1. Safety precautions in atomic pile control (1962)

    International Nuclear Information System (INIS)

    We have been led to study the problem of safety in atomic pile control as a result of our participation on the one hand in the planning of C.E.A. atomic piles, and on the other hand in the pile safety sub omission considering atomic pile safety of operational or planned C.E.A. piles. We have thus had to consider the wishes occurring in piles during their operation and also their behaviour in the dynamic state The present work deals mainly with the importance of intrinsic safety devices, with the influence of reactivity variations on the power fluctuations during accidental operation, and with the development of robust and reliable safety appliances. The starting p accident has been especially studied both for low-flux piles where a compromise is necessary between the response time of the safety appliances and the statistical fluctuations and for high lux piles where xenon poisoning has an effect on the lower limit of the velocity of reactivity liberation. The desirability has been stressed of automation as a safety factor in atomic pile control. The details required for an understanding of the diagrams of the apparatus are given. (author)

  2. Point resistance of piles in sand

    OpenAIRE

    Miura, Norihiko

    1983-01-01

    Mechanism of point resistance of pile in sand was investigated mainly from the viewpoint of the particle-crushing of sand at the pile tip. It is shown that the work dissipated in the particle-crushing of sand is as large as 66 percent of the total work done by the external force, hence the point resistance of a pile in sand greatly depends on the particle-crushing property of the sand. It is also shown that the relationship between point resistance and vertical pressure of a pile can be predi...

  3. Influence of reaction piles on test pile response in a static load test

    Institute of Scientific and Technical Information of China (English)

    Qian-qing ZHANG; Shu-cai LI; Zhong-miao ZHANG

    2013-01-01

    This work presents a new analytical method to analyze the influence of reaction piles on the test pile response in a static load test.In our method,the interactive effect between soil and pile is simulated using independent springs and the shear displacement method is adopted to analyze the influence of reaction piles on test pile response.Moreover,the influence of the sheltering effect between reaction piles and test pile on the test pile response is taken into account.Two cases are analyzed to verify the rationality and efficiency of the present method.This method can be easily extended to a nonlinear response of an influenced test pile embedded in a multilayered soil,and the validity is also demonstrated using centrifuge model tests and a computer program presented in the literature.The present analyses indicate that the proposed method will lead to an underestimation of the test pile settlement in a static load test if the influence of the presence of reaction piles on the test pile response is neglected.

  4. Journal bearing

    Science.gov (United States)

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

    1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

  5. Effect of pile-cap connection on behavior of torsionally loaded pile groups

    Institute of Scientific and Technical Information of China (English)

    Ling-gang KONG; Li-min ZHANG

    2008-01-01

    To evaluate the respouses of fixed and pinned pile groups under torsiun, a method is presented to analyze the nonlinear behavior of free-standing pile groups with rigid pile caps. The method is capable of simulating the nonlinear soil response in the near field usingp-y and τ-θ curves, the far-field interactions through Mindlin's and Randolph's elastic solutions, and the coupling effect of lateral resistance on torsional resistance of the individual piles using an empirical factor. Based on comparisons of the solutions for fixedand pinned-head, 1×2, 2×2, and 3×3 pile groups subjected to torsion, it was found that pile-cap connection significantly influences the torsional capacity of pile groups and the assignment of applied torques in the pile groups. In this study, the applied torques for the pinned-head pile groups are only 44%~64% of those for the corresponding fixed-head pile groups at a twist angle of 2°. Such a difference is mainly due to the change of the lateral resistances of individual piles in the groups.

  6. Steel Sheet Pile Walls in Soft Soil

    NARCIS (Netherlands)

    Kort, D.A.

    2002-01-01

    For almost a century, steel sheet pile walls are applied worldwide as earth retaining structures for excavations and quay walls. Within the framework of the development of European structural codes for Civil Engineering works, the Eurocodes, Eurocode 3 Part 5 for design of steel sheet pile walls was

  7. Analysis of pile load-transfer under pile-side softening

    Institute of Scientific and Technical Information of China (English)

    刘杰; 张可能

    2003-01-01

    A set of analytical equations for the variation of the axial force along depth and the pile-top load-settle-ment curve were established, using tri-linear softening model to pile-side soil and bilinear hardening model to pile-end soil . Influences of the pile-side and pile-end soil behavior on the load-settlement curve were discussed, indica-ting that the lowering reason for the variation step degree of the axial force along depth is the softening of the pile-side soil to result in the side friction lowering when the pile-top load is increased. To verify the reliability of thismethod, the parameters used in calculation are obtained from the test in Zhuzhou area. The obtained results are thencompared with the tested results. Contrast shows that the calculated results and the tested values are very close,which illustrates that the proposed method is reliable.

  8. Analysis of the Pile Foundation Calculation Process%解析桩基础计算过程

    Institute of Scientific and Technical Information of China (English)

    辛建雄

    2014-01-01

    This article bases on the specification of Guangd-ong province, specific analyses the calculation and design process of prestressed pipe pile. The author takes a residential district in Chaozhou as an example and specific elaborates its calculation of bearing capacity of pile and the pile foundation bearing capacity.%文章根据广东省规范,具体解析了预应力管桩的计算与设计过程。并以潮州市的一个住宅小区为例子,具体阐述了其桩承载力、桩基础承载力验算。

  9. Model Tests of Pile Defect Detection

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The pile, as an important foundation style, is being used in engineering practice. Defects of different types and damages of different degrees easily occur during the process of pile construction. So,dietecting defects of the pile is very important. As so far, there are some difficult problems in pile defect detection. Based on stress wave theory, some of these typical difficult problems were studied through model tests. The analyses of the test results are carried out and some significant results of the low-strain method are obtained, when a pile has a gradually-decreasing crosssection part, the amplitude of the reflective signal originating from the defect is dependent on the decreasing value of the rate of crosssection β. No apparent signal reflected from the necking appeares on the velocity response curve when the value of β is less than about 3.5 %.

  10. Physical modelling of pipe piles under oblique pullout loads using transparent soil and particle image velocimetry

    Institute of Scientific and Technical Information of China (English)

    曹兆虎; 刘汉龙; 孔纲强; 周航

    2015-01-01

    A small-scale physical modelling method was developed to investigate the pile bearing capacity and the soil displacement around the pile using transparent soil and particle image velocimetry (PIV) technique. Transparent sand was made of baked quartz and a pore fluid with a matching refractive index. The physical modelling system consists of a loading system, a laser light, a CCD camera, an optical platform and a computer for image analyzing. A distinctive laser speckle was generated by the interaction between the laser light and transparent soil. Two laser speckle images before and after deformation were used to calculate the soil displacement field using PIV. Two pipe piles with different diameters under oblique pullout loads at angles of 0°, 30°, 45°, 60° and 90° were used in tests. The load−displacement response, oblique pullout ultimate resistances and soil displacement fields were then studied. The test results show that the developed physical modelling method and transparent soil are suitable for pile−soil interaction problems. The soil displacements around the pipe piles will improve the understanding on the capacity of pipe piles under oblique pullout loads.

  11. 工程基桩检测的动静对比实例分析%Case analysis on dynamic and statistic contrast in engineering foundation pile detection

    Institute of Scientific and Technical Information of China (English)

    绳怀海; 孙海涛; 祝凤春

    2011-01-01

    Combining with engineering case,in order to accurately detects pile-side and pile-end resistance distribution condition,it carries on dynamic and statistic load test and high strain dynamic detection for the pile foundation,and analyzes and evaluates the detection results.In the end,it obtains that is feasible to use high strain dynamic detection of pile foundation to determine the foundation pile bearing capacity.%结合某工程实例,为了准确测定桩侧、桩端阻力分布情况,对基桩进行了动静载测试及高应变动力检测,并对检测结果进行了分析评价,得出用基桩高应变动力检测确定基桩承载力是可行的。

  12. PILE-SOIL INTERACTION TEST OF FILLING PILE AND MODELING STUDY BY THE FINITE ELEMENT METHOD%灌注桩桩土相互作用试验及有限元模拟研究

    Institute of Scientific and Technical Information of China (English)

    赵法锁; 俞剑勇; 罗丽娟; 卢全中; 胡志平

    2001-01-01

    以灌注桩桩土相互作用的原位试验为基础,结合西安土层结构、性质;采用有限单元法对黄土地区的砼灌注桩桩—土相互作用进行仿真模拟,研究了 桩土相互作用、荷载的传递规律、桩土相对位移与桩侧摩阻力的关系。通过桩载试验资料 对比,得出三维有限单元法的模拟结果与实测值相近,该研究进一步揭示了桩土相互作用的实质,为最优桩长的选取和单桩承载力的确定奠定了基础。%Based on the in situ test of pile-soil interaction of filling pile, combining with the properties of soils in Xi′an, and modelings pile-soil interaction of concrete filling pile in the loess area by using finite element method, the authors studied pile-soil interaction, regulari ty of load transferring, and the relation between relative displacement and lateral friction resistance of the pile. By comparing of pile load test data,it is found that the modeling result by three-dimensional finite element method is similar to that of actual measurement. Moreover, the essence of pile-soil interaction is revealed. It provides a basis for the selection of optimum pilele ngth and the definition of pile bearing capacity.

  13. Experimental Modeling of Pile-Leg Interaction in Jacket Type Offshore Platforms Cyclic Inelastic Behavior

    Directory of Open Access Journals (Sweden)

    M. R. Honarvar

    2008-01-01

    Full Text Available Offshore platforms in seismically active areas should be designed to survive in the event of severe ground excitations with no global structural failure. The annulus between the pile and leg in jacket-type offshore platforms can be filled with cement grout as a means of reducing horizontal deflections, inhibiting corrosion and preventing local damages. This paper discusses an experimental approach which can be used to demonstrate the effect of grouting on enhanced structural performance of jackets. In this regard, the lateral load bearing behavior of grouted and un-grouted jackets are investigated experimentally with special attention to effect of grout on pile-leg interaction. Results are presented on the cyclic inelastic behavior of two scaled frame models of a representative platform which was recently installed in the Persian gulf. The objective of this effort was to improve the understanding of the behavior of jackets subjected to lateral motions and specially the effects of exact real pile-leg interaction. it should be noted that this paper addresses the exact and realistic pile-leg interaction. It is concluded that grouting can not be considered as a definite method of improving strength and structural nonlinear dynamic behavior. Although it generally increases the lateral stiffness, but some side effects and points are to be considered. In this paper, the two separate lateral load bearing mechanisms -namely portal (braced mechanism and frame bending mechanism- are distinguished and the effect of grout on each one is shown.

  14. A new method for testing pile by single-impact energy and P-S curve

    Institute of Scientific and Technical Information of China (English)

    许昭永; 段永康; 王彬; 胡毅力; 杨润海; 许峻; 赵晋明

    2004-01-01

    By studying the pile-formula and stress-wave methods (e.g., CASE method), the authors propose a new method fortesting piles using the single-impact energy and P-S curves. The vibration and wave figures are recorded, and thedynamic and static displacements are measured by different transducers near the top of piles when the pile is impacted by a heavy hammer or micro-rocket. By observing the transformation coefficient of driving energy (totalenergy), the consumed energy of wave motion and vibration and so on, the vertical bearing capacity for single pileis measured and calculated. Then, using the vibration wave diagram, the dynamic relation curves between the force(P) and the displacement (S) is calculated and the yield points are determined. Using the static-loading test, thedynamic results are checked and the relative constants of dynamic-static P-S curves are determined. Then the subsidence quantity corresponding to the bearing capacity is determined. Moreover, the shaped quality of the pilebody can be judged from the formation of P-S curves.

  15. The stiffness change and the increase in the ultimate capacity for a stiff pile resulting from a cyclic loading

    DEFF Research Database (Denmark)

    Lada, Aleksandra; Ibsen, Lars Bo; Nicolai, Giulio

    In the paper the experimental results of small-scale tests on a stiff monopile are presented to outline the change in stiffness during the cyclic loading and the change in the ultimate pile capacity. The results confirm the increase of stiffness and the increase in bearing capacity resulting from...

  16. GAS BEARING

    Science.gov (United States)

    Skarstrom, C.W.

    1960-09-01

    A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

  17. 3D finite element analysis on pile-soil interaction of passive pile group

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-hua; LIU Dun-ping; ZHANG Ling; JIANG Chong

    2008-01-01

    The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plastic complying with the Drucker-Prager yield criterion in the analysis. The large displacement of soil was considered and contact elements were used to evaluate the interaction between pile and soil. The influences of soil depth of layer and number of piles on the lateral pressure of the pile were investigated, and the lateral pressure distributions on the (2×1) pile group and on the (2×2) pile group were compared. The results show that the adjacent surcharge may result in significant lateral movement of the soft soil and cousiderable pressure on the pile. The pressure acting on the row near the surcharge is higher than that on the other row, due to the "barrier" and arching effects in pile groups. The passive load and its distribution should be taken into account in the design of the passive piles.

  18. Vertical vibration of a large diameter pipe pile considering transverse inertia effect of pile

    Institute of Scientific and Technical Information of China (English)

    郑长杰; 刘汉龙; 丁选明; 周航

    2016-01-01

    Considering the transverse inertia effect of pile, the vertical dynamic response of a large diameter pipe pile in viscoelastic soil layer is studied. The wave propagations in the outer and inner soil are simulated by three-dimensional elastodynamic theory and those in the pile are simulated by Rayleigh-Love rod theory. The vertical and radial displacements of the outer and inner soil are obtained by utilizing Laplace transform technique and differentiation on the governing equations of soils. Then, based on the continuous conditions between the pile and soils, the displacements of the pile are derived. The frequency domain velocity admittance and time domain velocity response of the pile top are also presented. The solution is compared to a classical rod model solution to verify the validity. The influences of the radii and Poisson ratio of pile on the transverse inertia effect of pile are analyzed. The parametric study shows that Poisson ratio and outer radius of pile have significant influence on the transverse inertia effect of large diameter pipe piles, while the inner radius has little effect.

  19. Analysis of effect of different construction methods of piles on the end effect on skin friction of piles

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hongbo; CHEN Zhuchang

    2007-01-01

    Based on the comparative analysis of end effect on skin friction of displacement-pile (driven pile),the end effect on skin friction of bored pile is studied.The end effect on skin friction between driven pile and bored pile is different and the end effect on skin friction of bored pile is reduce of skin friction in the soil layer adjacent to the pile end.The degradation degree of skin friction is deduced with the increase of the distance from pile end.The concept of additional mud cake formed by the effect of cushion at the bottom of borehole during pouring concrete is introduced to explain the mechanism of end effect on skin friction of the bored pile.The test results of post-grouting piles indicate that the post-grouting technique is an effective way to improve the end effect on skin friction of bored pile.

  20. Centrifuge model test on dynamic behavior of group-pile foundation With inclined piles and its numerical simulation

    Institute of Scientific and Technical Information of China (English)

    Feng ZHANG; Katsunori OKAWA; Makoto KIMURA

    2008-01-01

    In this paper, dynamic behavior of a grouppile foundation with inclined piles in loose sand has been investigated with centrifuge model tests. The test results are also simulated with elastoplastic dynamic finite ele-ment method, in which, not only sectional force of piles, stress of ground, but also deformation of piles are calcu-lated using a three-dimensional elastoplastic dynamic finite element analysis (Code name: DGPILE-3D). The numerical analyses are conducted with a full system in which a superstructure, a pile foundation and surround-ing ground are considered together so that interaction between pile foundation and soils can be properly simu-lated because the nonlinearities of both the pile and the ground are described with suitable constitutive models. Different types of piles, vertical pile or inclined pile, are considered in order to verify the different characteristics of a group pile foundation with inclined piles. The validity of the calculation is verified by the model tests.

  1. Grizzly bear

    Science.gov (United States)

    Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.

    2003-01-01

    The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

  2. A simplified algorithm for the design of piled raft foundations applied for the case study of a building erected within Żoliborz-Szczęśliwice glacial tunnel valley

    Directory of Open Access Journals (Sweden)

    Kacprzak Grzegorz

    2015-06-01

    Full Text Available A common engineering solution for excessive settlement with raft foundation (s is the use of piles in order to reduce the vertical displacements, in this method, the whole structural load is transferred to the piles. This is an overly cautious approach, and there remains a need to find an optimal design method for a building’s foundations. Such a solution may be the piled raft foundation, which allows a reduction of the number of piles due to the integration of the raft in the bearing capacity of the foundation. The aim of the article is to estimate the contribution of foundation elements such as the raft and the piles in the bearing capacity of a residential building located in Warsaw, where the geological conditions are characterized by organic soil layers, principally of gyttja.

  3. Safety precautions in atomic pile control (1962); Securite dans le controle des piles atomiques (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Furet, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    We have been led to study the problem of safety in atomic pile control as a result of our participation on the one hand in the planning of C.E.A. atomic piles, and on the other hand in the pile safety sub omission considering atomic pile safety of operational or planned C.E.A. piles. We have thus had to consider the wishes occurring in piles during their operation and also their behaviour in the dynamic state The present work deals mainly with the importance of intrinsic safety devices, with the influence of reactivity variations on the power fluctuations during accidental operation, and with the development of robust and reliable safety appliances. The starting p accident has been especially studied both for low-flux piles where a compromise is necessary between the response time of the safety appliances and the statistical fluctuations and for high lux piles where xenon poisoning has an effect on the lower limit of the velocity of reactivity liberation. The desirability has been stressed of automation as a safety factor in atomic pile control. The details required for an understanding of the diagrams of the apparatus are given. (author) [French] Nous avons aborde le probleme de la securite dans le controle des piles atomiques a la suite de notre participation d'une part aux avant rojets de piles atomiques du CE.A. et d'autre part a l'examen au sein de la sous ommission de surete des piles, de la securite des piles du CE.A. en fonctionnement ou en projet. Nous avons ete amenes a nous interesser alors aux risques encourus par les piles pendant leur fonctionnement et par la meme a leur comportement en regime dynamique. Ce travail traite principalement de l'importance des securites intrinseques, de l'influence des variations de reactivite sur les evolutions de puissance en regime d'accident et du developpement d'appareillages de securite robustes et de fonctionnement tres sur. L'accident de demarrage a ete particulierement

  4. Numerical Analysis of Piles in Layered Soils: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Ravi Kumar Reddy C

    2015-04-01

    Full Text Available In this paper, numerical analysis of a pile-soil interaction problem is presented considering the parameters influencing the axial load-deformation behavior of the pile embedded in a layered soil medium. The analysis is demonstrated with parametric solutions of a pile with underlain model soil strata under the axial force. An attempt is made to ascertain the extent of influence of elastic properties of the pile, geometry of the pile, end conditions of the pile and the elastic properties of the underlain soil strata on the response of the piles under axial loads lying in a model soil layers in terms of the settlement of the pile and the internal deformation of the pile. The study revealed that the increase in modulus of elasticity of pile improves the settlement resistance of the pile, increase in the ratio of cross sectional dimensions causes decrease in the top deformations of the pile, the settlement of the pile reduced to a great extent when the cross section of the pile adopted is non circular instead of circular and increase in the elastic modulii of top and bottom layers of soil has decreased the settlement of the pile to a great extent, but elastic modulus of soil layers other than top and bottom has got negligible influence on the settlement of the pile.

  5. 30 CFR 77.214 - Refuse piles; general.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles; general. 77.214 Section 77.214... Installations § 77.214 Refuse piles; general. (a) Refuse piles constructed on or after July 1, 1971, shall be..., tipples, or other surface installations and such piles shall not be located over abandoned openings...

  6. 30 CFR 816.83 - Coal mine waste: Refuse piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Coal mine waste: Refuse piles. 816.83 Section... ACTIVITIES § 816.83 Coal mine waste: Refuse piles. Refuse piles shall meet the requirements of § 816.81, the... drainage may not be diverted over the outslope of the refuse piles. Runoff from the areas above the...

  7. 30 CFR 817.83 - Coal mine waste: Refuse piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Coal mine waste: Refuse piles. 817.83 Section... ACTIVITIES § 817.83 Coal mine waste: Refuse piles. Refuse piles shall meet the requirements of § 817.81, the... drainage may not be diverted over the outslope of the refuse pile. Runoff from areas above the refuse...

  8. 30 CFR 77.215-4 - Refuse piles; abandonment.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles; abandonment. 77.215-4 Section 77... MINES Surface Installations § 77.215-4 Refuse piles; abandonment. When a refuse pile is to be abandoned... refuse pile shall be abandoned in accordance with a plan submitted by the operator and approved by...

  9. Research on Mechanism and Dynamic Characteristics of Composite Foundation with Multi-type Piles%多桩型复合地基作用机理与动力特性研究

    Institute of Scientific and Technical Information of China (English)

    张艳美; 潘振华; 张鸿儒; 王震; 黄春霞

    2015-01-01

    To meet the requirements of bearing capacity and anti-liquefaction of liquefiable founda-tions,the reinforcement of liquefiable soil using CFG piles combined with gravel piles is used in engineering.In this study,a composite foundation with multi-type piles composed of gravel piles and CFG piles was analyzed.In composite foundations with multi-type piles,gravel piles are sup-plemented piles that are mainly used to accelerate the foundation drainage consolidation.CFG piles are the main piles that undertake greater seismic load and reduce the dynamic pore pressure and post-earthquake settlement of the foundation.A composite foundation with multi-type piles com-posed of gravel and CFG piles can improve the bearing capacity and liquefaction resistance of a liquefiable foundation.A three dimensional numerical model was established and the dynamic characteristics of a composite foundation with multi-type piles was studied through numerical simulation;the influence of design parameters such as the ratio of pile type,pile diameter,pile length,CFG pile body stiffness,and gravel pile body permeability on dynamic characteristics of a composite foundation with multi-type piles was analyzed.The results show that the dynamic de-formation of a composite foundation,including gravel pile composite foundation,CFG pile com-posite foundation,and composite foundation with multi-type piles is obviously smaller than that of a natural foundation during earthquakes,and the dynamic deformation decreases with increase in the number of CFG piles.When the ratio of gravel piles and CFG piles is 4:5,the dynamic de-formation curve of a composite foundation with multi-type piles is close to that of the CFG pile composite foundation and the influence of the increase in the amount of CFG piles on the reduc-tion in the dynamic deformation of the composite foundation is no longer obvious.When the ratio of gravel piles and CFG piles is 4:5,the dynamic pore water pressure of the composite foundation

  10. Efficient stock piling of 40mm shells

    Directory of Open Access Journals (Sweden)

    J. N. Nanda

    1958-10-01

    Full Text Available A problem was posed as to discuss efficient stock-piling of 40mm shells. There is, in fact no data from which emergency requirements can be deduced. A figure has been quoted by Army authorities that E rounds per month are required during an emergency. The size of the emergency stock pile will depend upon the difference of the normal peace time production, and also on the time taken for the crash programme of emergency production to come into fulfillment. In addition the delivery time from factories to the stock piles is also kept in view.

  11. 预应力管桩终压值控制静压施工技术%Construction Technology of Controlling Static Pressure on the Base of Prestressed Pile Final Pressure Value

    Institute of Scientific and Technical Information of China (English)

    徐左屏; 许小云

    2014-01-01

    In order to resolve the shallow strong supporting layer prestressed pipe pile capacity and pile strength matching problem, this paper adopted end bearing friction supplemented pile design on the base of the final pressure value PU and detection limit value. Through exploring holes, static pressure, sending piles, pile tip bearing stratum strong compaction, final pressure value control, regulation and grouting technology, under the same type of pile, pile length and pile pressure conditions, this kind of design can increase the pile bearing capacity of 30% to 40%, effectively reduce the initial pile and uneven settlement, fundamentally solve the dilemma of waste of resources and finally meet the requirement of conservation of pile design and low construction costs.%为了解决浅强持力层预应力管桩单桩承载力和桩身强度匹配问题,采用端承为主、摩擦为辅的桩型设计,以桩身允许抗压强度作为终压值PU和试验检测极限值的依据,通过探孔、静压、送桩、桩尖持力层强挤密、终压值控制、稳压和注浆技术,在相同桩型、桩长和压桩工艺条件下提高单桩承载力30%~40%,有效减少桩基初始和不均匀沉降,从根本上解决资源浪费和节约桩基设计、施工成本。

  12. Analysis on Pile-Soil Load Transfer Behaviour of Drilling and Fiuld Compress Pile%钻孔压浆桩桩土荷载传递性状分析

    Institute of Scientific and Technical Information of China (English)

    徐松林; 吴文; 张华; 胡恒初; 姚春桥

    2001-01-01

    The construction process of drilling and fluid compress pile and that of drilling and grouting pile are different, so the load transfer behaviours between pile and soil are also varied. sliding micrometer is used herein to measure the axial strain of the drilling and fluid compress pile and the load transfer behaviours of pile-soil are analyzed in association with static load tests. The results indicate the said technique can both improve the bearing capacity of pile and also be economical.%钻孔压浆桩与钻孔灌注桩和后压浆技术在施工工艺上不同,其桩土荷载传递性状亦有差异。本 文应用滑动测微计测试钻孔压浆桩桩身轴向应变,结合静载试验分析了桩土荷载传递性状。其结果表 明,与其他两种基础处理方法相比,它的应用不仅改善了桩的承载性能,而且也具有经济优势。

  13. Bearing capacity improvement using micropiles a case study

    OpenAIRE

    Babu, Sivakumar GL; Murthy, Srinivasa BR; Murthy, DSN; Nataraj, MS

    2004-01-01

    Micropiles have been used effectively in many applications of ground improvement to increase the bearing capacity and reduce the settlements particularly in strengthening the existing foundations. Frictional resistance between the surface of the pile and soil and the associated group/network effects of micropiles are considered as the possible mechanism for improvement. This paper deals with a case study in which micropiles of 100 mm diameter and 4 m long have been used to improve the bearing...

  14. The Pile-soil interaction analysis about bank connecting structure of blind sheet-pile%遮帘板桩式接岸结构桩土相互作用分析*

    Institute of Scientific and Technical Information of China (English)

    周世良; 程烈; 沈灵; 凌霄

    2013-01-01

      Based on a project, we carry out a numerical analysis for the pile-soil interaction of the blind sheet-pile bank connecting structure. We also study the effect of the calculation parameters on the pile-soil interaction. When the blind sheet-pile suffers the rear earth pressure, the earth pressure among the sheet-pile passes to both sides of the barrier piles, so that it reduces the earth pressure bore by the front piles which produces the soil arching effect, and improves the bearing capacity of the bank connecting structure. It is found that the soil cohesion and the internal friction angel have greater impacts on pile-soil interaction. With the cohesion and internal friction angel increase, the load-bearing of blind piles also increases, and finally tends to a stabilized value. When the cohesive reaches to a certain value, the internal friction angel has a less impact on the pile-soil interaction. In order to make an optimal design, we must make a comprehensive consideration about not only the span of the blind pile but also the span between the blind pile and the front row pile. It can be used as a secondary factor when designing the bank connecting structure of the blind sheet pile, because the soil elastic modulus, Poisson’s ration and the coefficient of friction of the pile have small effects on the pile-soil interaction.%  结合某工程,对遮帘板桩式接岸结构桩土相互作用进行数值分析,研究了桩土相关计算参数对桩土作用的影响。由于遮帘桩的存在,在受到后方土压力时,遮帘桩桩间土压力向两侧遮帘桩传递,这样减小了前排桩承受的土压力,产生土拱效应,提高了接岸结构的承载力。土的粘聚力与内摩擦角对桩土相互作用影响较大,随着粘聚力与内摩擦角的增加,遮帘桩荷载承担比均有所增加,最后都趋于稳定值,当粘聚力达到一定值时,内摩擦角对桩土相互作用影响较小。遮帘桩间距及

  15. INTERACTION BETWEEN LONG PILES AND THE SOIL BODY AS PART OF THE SLAB-PILE FOUNDATION

    OpenAIRE

    Ter-Martirosyan ZavenGrigorevich; Trinh Tuan Viet

    2012-01-01

    The paper provides a definition of and a solution to the problems of interaction between long piles and the soil body as part of the slab-pile foundation with the due account for the interval between the piles, the length of piles and their correlations, as well as the nonlinear properties of soil identified by analytical and numerical methods through the application of Plaxis-2d software. It is proven that the above properties produce a substantial impact onto the stress-strain state of s...

  16. Modelling the dynamic pile-soil-pile interaction in a multi-layered half-space

    OpenAIRE

    Hamad, Waleed; Ntotsios, Evangelos; Hunt, Hugh; Hussein, M.F.M.; Thompson, D. J.; Talbot, James

    2015-01-01

    Within the context of railway ground-borne vibration, the dynamic pile-soil-pile interaction remains an area that has not been sufficiently investigated. Whilest a number of researchers have scrutinised the vibration response of piled-foundations, their approaches exhibit a compromise between computation time and solution accuracy. In this paper, two models of piled-foundations in a multi-layered half-space are presented; one is an efficient semi-analytical model and another is a fully-couple...

  17. The Effect of Soil-Pile Interface Behaviour on Laterally Loaded Piles

    DEFF Research Database (Denmark)

    Zania, Varvara; Hededal, Ole

    2011-01-01

    In current practice it is either the p – y curve concept, or analytical solutions assuming different formulations for ultimate soil resistance that are being used to evaluate the lateral pile response. The adequacy of the p – y curves or of the assumed pressure distribution and ultimate soil...... resistance have been questioned. In this study the lateral capacity of three-dimensional numerical models of rigid piles embedded in cohesionless soil was estimated. The potential variability of the friction properties along the perimeter of the pile was considered. The interface properties affect...... the ultimate soil resistance and the stiffness of the soil–pile response....

  18. Non-linear response of coupled soil-pile-structure system under sinusoidal excitations with various frequencies

    Science.gov (United States)

    Hussien, Mahmoud N.; Tobita, Tetsuo; Iai, Susumu

    The non-linear response of coupled soil-pile-structure systems to seismic loading is parametrically studied in the frequency domain using two-dimensional (2D) finite elements (FE). The soil-pile interaction in three dimensions (3D) is idealized in the 2D type using soil-pile interaction springs with non-linear hysteretic load displacement relationships. The system under investigation comprises of a single degree of freedom structure supported by an end-bearing single pile founded in a homogenous sand layer over rigid rock. Comparisons with established results from the literature suggest that the adopted FE model reasonably captures the essential features of the seismic response of the coupled soil-pile-structure system. Numerical results demonstrate the strong influence on the effective natural period of the foundation properties. The effect of non-linear soil behavior and soil profile as well as the frequency content of excitation on both kinematic and inertial interactions is illustrated. The relative contributions of kinematic and inertial interaction to the development of dynamic pile bending are clarified.

  19. Study on rock-socketed PHC pile foundation by test%嵌岩PHC桩基试验研究

    Institute of Scientific and Technical Information of China (English)

    吴建; 陈超; 高倚山; 金红星

    2012-01-01

    工程领域采用的PHC桩基多以粘性土、砂性土层为持力层,文中给出了在复杂中软土地基条件下,以风化岩为持力层,进行PHC桩嵌岩试验的工程实例。通过沉桩试验、高应变动测、静载荷试验等,综合讨论了PHC桩实施嵌岩的可行性,总结分析了岩土工程勘察的侧重点,提出了加强桩身强度、优化桩靴设计和控制沉桩锤击力等措施确保嵌岩桩身质量的一些认识。%Bearing stratum of PHC piles generally adopts clay and sandy soil in construction project.In the condition of complicated soft soil foundation,this paper makes experiments on rock-socketed PHC pile,which adopts weathered bedrock as bearing stratum.By pile driving test,high-strain dynamic test and static loading test,this paper analyzes the feasibility of PHC pile driven into bedrock.And this paper summarizes the key point of geotechnical engineering investigation and suggests some measures in order to ensure the quality of rock-socketed PHC pile,such as strengthening pile body,optimizing pile shoe and controlling hammer energy.

  20. Local Scour Around Piles Under Wave Action

    Institute of Scientific and Technical Information of China (English)

    陈国平; 左其华; 黄海龙

    2004-01-01

    The model tests are performed with regular waves, and the effect of wave height, wave period, water depth, scdiment size and pile diameter is evaluated. The shape and size of local scour around piles are studied. There are three typical scour patterns due to wave action. It is found that a relationship exists between the erosion depth and the wave number. An empirical formula of the maximum local scour is thus derived.

  1. Seismic soil pile interaction:experimental evidence

    OpenAIRE

    Moccia, Flaviana

    2009-01-01

    The comprehension of the real behaviour of pile foundations under earthquake loading is very important, since it can significantly affect the performance of the superstructure. As a matter of fact the experience of recent earthquake has confirmed that piles can suffer extreme damage and failure under earthquake loading. The case histories from Kobe earthquake (1995) indicate that not only the inertial actions but also the kinematic ones, due to ground movements, which was overlooked in design...

  2. Experimental Research on Comparison of High Strain Dynamic Testing and Static Loading Test on Vertical Bearing Capacity for Large Diameter Manual Hole Digging Pile%大直径人工挖孔桩竖向承载力动静对比试验研究

    Institute of Scientific and Technical Information of China (English)

    洪辉煌

    2015-01-01

    在介绍静载荷试验和高应变法的基础上,结合工程实例对它们的检测结果进行对比,由此检验高应变法检测大直径人工挖孔桩的精度.%Based on the introduction of high strain dynamic testing and static loading test,and combined with the engineering example,the testing results were compared in this paper. Thereout,it could check up the testing precision of high strain dynamic testing on large diameter manual hole digging pile.

  3. Grouting of uranium mill tailings piles

    International Nuclear Information System (INIS)

    A program of remedial action was initiated for a number of inactive uranium mill tailings piles. These piles result from mining and processing of uranium ores to meet the nation's defense and nuclear power needs and represent a potential hazard to health and the environment. Possible remedial actions include the application of covers to reduce radon emissions and airborne transport of the tailings, liners to prevent groundwater contamination by leachates from the piles, physical or chemical stabilization of the tailings, or moving the piles to remote locations. Conventional installation of liners would require excavation of the piles to emplace the liner; however, utilization of grouting techniques, such as those used in civil engineering to stabilize soils, might be a potential method of producing a liner without excavation. Laboratory studies on groutability of uranium mill tailings were conducted using samples from three abandoned piles and employing a number of particulate and chemical grouts. These studies indicate that it is possible to alter the permeability of the tailings from ambient values of 10-3 cm/s to values approaching 10-7 cm/s using silicate grouts and to 10-8 cm/s using acrylamide and acrylate grouts. An evaluation of grouting techniques, equipment required, and costs associated with grouting were also conducted and are presented. 10 references, 1 table

  4. 微型桩芯搅拌桩工程实践与工作机理研究%Project practice and work mechanism about micropile-core cement mixing pile

    Institute of Scientific and Technical Information of China (English)

    包华; 邓亚光; 张慧

    2012-01-01

    微型桩芯水泥搅拌桩复合地基在江苏沿海、沿江地区广泛应用。结合实际工程简要介绍了该复合桩的施工工艺与构造、承载力设计方法。研究了桩芯、桩体与地基土三者之间的应力分布与荷载分担规律。结果表明,微型桩芯的打入提高了复合桩与桩周土之间的摩阻力,复合桩表现出摩擦桩工作特性。微型桩芯搅拌桩复合地基具有刚性桩复合地基的工作特点,荷载通过桩芯到桩体再到桩周土逐步向外有效地扩散到整个基础持力层。%Composite foundation composited of micropile-core cement mixing pile and foundation soil is widely used in coastal and riverside area of Jiangsu.Based on the actual project practice,the construction technology,details and design method of bearing capacity for this composited pile were introduced.Stress distribution and load share law were studied among pile core,mixing-pile body and foundation soil.The results show that piling core can enhance the friction force between piles and soil around pile.Composite pile shows the working characteristics of friction pile.This composited piled foundation is rigid,and the load can be transferred effectively from inside to outside through pile core,mixing-pile body and soil around pile.

  5. Foil bearings

    Science.gov (United States)

    Elrod, David A.

    1993-11-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  6. Study on pile drivability with one dimensional wave propagation theory

    Institute of Scientific and Technical Information of China (English)

    陈仁朋; 王仕方; 陈云敏

    2003-01-01

    Pile drivability is a key problem during the stage of design and construction installation of pile foundations. The solution to the one dimensional wave equation was used to determine the impact force at the top of a concrete pile for a given ram mass, cushion stiffness, and pile impedance. The kinematic equation of pile toe was established and solved based on wave equation theory. The movements of the pile top and pile toe were presented, which clearly showed the dynamic displacement, including rebound and penetration of pile top and toe. A parametric study was made with a full range of practical values of ram weight, cushion stiffness, dropheight, and pile impedance. Suggestions for optimizing the parameters were also presented. Comparisons between the results obtained by the present solution and in-situ measurements indicated the reliability and validity of the method.

  7. The Effect of the Propeller Jet on Pile Groups

    Institute of Scientific and Technical Information of China (English)

    Kubilay Cihan

    2014-01-01

    The objective of this study is to determine the effect of jet propeller on the damage of berthing structures combined of armoured slope with pile groups. For this purpose, scour measurements were performed for four types berthing structures, which were armoured slope with tandem arrangements of piles for two and three piles and with side by side arrangements of piles for two and three piles. The effect of gap between piles on damage was investigated. The damage level induced by propeller jet between piles was determined. The gaps were 1, 2, 3, and 4 times the pile diameter. Three different values of Rpm (690, 820, and 950) were chosen for the tests. The diameter of circular piles is 40 mm. The slope ratio was 1/3 and the diameter of propeller was 10 cm.

  8. 大直径(超)长灌注桩竖向载荷试验研究%Study on large diameter and (super) long bored piles by using vertical loading tests

    Institute of Scientific and Technical Information of China (English)

    张添文; 陈广才

    2013-01-01

    本文通过厦门某项目大直径(超)长灌注桩桩端有无注浆、不同持力层的对比静载试验以及基坑底大吨位(6000kN)抗拔试验,分析研究大直径(超)长灌注桩的竖向承载性能,得出以下结论和建议:抗压桩、抗拔桩均存在侧阻力时间效应因素的影响而降低桩侧摩阻力,当暴孔约9d,抗压桩桩侧摩阻力降低约23%,抗拔桩桩侧摩阻力降低约1/3;采用S-lgP法和经验参数法(结合静载试验)分离桩侧摩阻力和桩端阻力,表明大直径超长灌注桩即使是嵌岩桩通常也属于端承摩擦桩,侧摩阻力先于端阻力发挥,故应先满足桩身压屈变形,才能保证桩端阻力的发挥;不管是抗压桩还是抗拔桩,可优先考虑桩侧注浆,可较大幅度提高桩侧摩阻力,而不要盲目增加桩长或嵌岩深度;桩侧抗拔土阻力峰值对应的桩顶上拔量同样约为0.02D,当桩周土层为全风化岩—强风化岩时,抗拔系数约为0.60.%Based on the static loading tests with the post grouting or not for the cast-in-situ piles for a project in Xiamen with large diameter and (super) long bored piles,the contrast static loading tests on pile tip in different soils,and the uplift static loading tests in foundation pit with big load 6000kN,the vertical bearing performance of the large diameter and (super) long bored piles is analyzed on the basis of many groups of contrast vertical loading tests.The conclusions and suggestions are as follows:the pile side friction resistance of compressive pile or uplift pile is reduced because of the time effect; when the finished bore hole is in air for 9 days,the side friction resistance of compressive pile is reduced about 23%,and the uplift pile is reduced about 1/3 ; with the S-lgP method or the empirical coefficient method (combined with loading tests),the pile side friction and the pile tip resistance are separated,which shows that large diameter and super long bored piles usually belong to the end

  9. Analytical Analysis and Field Test Investigation of Consolidation for CCSG Pile Composite Foundation in Soft Clay

    Directory of Open Access Journals (Sweden)

    Jin Yu

    2013-01-01

    Full Text Available Low-grade concrete-cored sand-gravel (CCSG pile composite foundation is a new kind of composite foundation for thick and soft clay ground treatment. An analytical solution was derived for calculating the consolidation process of this composite foundation by considering coefficients of horizontal permeability in smear zone, the radial flow within the sand-gravel shell, and the impervious property of concrete-cored pile. The results show that Terzaghi’s one-dimensional consolidation solution and the consolidation analytical solution of ordinary composite foundation were special cases of this solution. Curves of the average consolidation degree of the composite foundation under various nondimensional parameters were observed using the program based on the theoretical formula. Meanwhile, a series of in situ measurements including the settlement of pile and soil, the pore water pressure, and the total stress under embankment load were obtained on the CCSG pile composite foundation on a section of Zhenjiang-Liyang highway. The analyzed results show that the new style composite foundation patent technology has many advantages such as small differential postconstruction settlement (differential is not good, small is, reliable quality, high bearing capacity, and stability. And the consolidation of composite foundation is largely affected by the nondimensional parameters. The analytical solution is finally verified with the actual measurement data.

  10. Determination of pile failure mechanism under pullout test in loose sand

    Institute of Scientific and Technical Information of China (English)

    K. Faizi; R. Kalatehjari; R. Nazir; A. S. A. Rashid

    2015-01-01

    Estimating the deformation of soil around the pile contributes to reliable design of structures under pullout force. This work presents the results of a series of small-scale physical modelling tests designed to investigate the uplift resistance of piles with diameter of 5 cm and slenderness ratios of 1, 2, 3 and 4 in loose sand. Close photogrammetric technique and particle image velocimetry (PIV) were employed to observe the failure patterns due to uplift force on piles. The results show that the shear zones curve slightly outward near the ground surface. After peak resistance, the shear strain concentrates into a pair of narrow shear bands, then a flow around mechanism is formed accompanied by a reduction in the uplift resistance. The results from the laboratory tests were verified by analytical method proposed by Chattopadhyay and PLAXIS 2D and 3D finite element method software. It is found that the depth and width of the failure surface increase with the increment of the slenderness ratio. A good agreement is observed among the measured bearing capacity and obtained failure surface of the models and the results of numerical modelling. Finally, the maximum deformation of loose and dense sand respectively with densities of 25% and 75% were compared in the stage of fully removing pile. The results shows that the deformation of the soil is related to its density, therefore it depends on its dilatancy.

  11. Wavelet analyses for stress wave detection of piles

    Institute of Scientific and Technical Information of China (English)

    WANG; Jingtao; (王靖涛)

    2003-01-01

    The theoretical foundation for application of wavelet analysis to pile integrity detection has been presented. The mechanism of spectral variations of reflected pulse from various defects in piles is explained by using the wave scattering theory. The theoretical analyses have been verified through the tests of model piles and a lot of engineering piles. A quantitative evaluation method for estimating damage degree of piles is proposed. The characteristic indexes describing spectrum variations of reflected signals and their critical values are given. They can be used not only to evaluate the damage degree but also to identify the kinds of pile defects.

  12. 埕岛粉喷桩复合地基应力比试验%Experiment of pile-soil stress ratio of DJM pile composite foundation in Chengdao

    Institute of Scientific and Technical Information of China (English)

    颜庆智; 闫相祯; 江立群

    2011-01-01

    桩土应力比是反映桩体和桩间土协同工作的重要指标,也是复合地基承载力和沉降计算的重要参数,与地基土的物理力学性质密切相关,影响因素复杂.结合某大型工程,首次对埕岛软土上粉喷桩复合地基进行大型应力比试验,得到埕岛粉喷桩复合地基应力比随荷载、时间、褥垫层厚度、褥垫层刚度的变化规律,并进行有限元分析,对两种结果进行对比.结果表明:粉喷桩复合地基桩土应力比值没有时间效应;粉喷桩复合地基桩土应力比与褥垫层厚度负相关,一定厚度褥垫层可协调桩土工作,宜试验确定最佳厚度范围;应力比与褥垫层弹性模量正相关,模量达到某一值时桩土应力比不再变化,应根据桩体材料选用适当弹性模量褥垫材料;该地区粉喷桩复合地基桩土应力比主要分布在6.5~9.0.%Pile-soil stress ratio is a very important indicator to reflect the level of the together-work of the pile and soil, also a major parameter calculating bearing capacity of composite foundation and settlement, and it is interrelated with the physical and mechanical properties of the soil, whose influencing factor is also complicated. Combined with a large-scale project, the large stress ratio test to the DJM pile composite foundation in the soft clay of Chengdao was conducted. The regulations of the pile-soil stress ratio of DJM pile composite foundation with the change of load, time, thickness and stiffness of pillow in Chengdao region were obtained. The finite element analysis was carried out, and these two results were compared. The results show that there is no time effect to the pile-soil stress ratio of DJM pile composite foundation. The pile-soil stress ratio of DJM pile composite foundation is negative correlation to the thickness of pillow. The pillow with a certain thickness could coordinate the work of the pile-soil, and the best thickness range should be confirmed by

  13. 关于桩基设计若干问题的探讨%Some Issues of pile foundation design

    Institute of Scientific and Technical Information of China (English)

    陈义侃

    2012-01-01

    There has been a lot of discussion about the issue of pile design, this paper only discussed the problems encountered in design, review, construction drawing review, such as vertical bearing capacity problem, pile layout problem, problem of soil liquefaction, pile body strength. It is hoped everybody to participate in the discussion and correct some mistakes.%桩基设计中有关问题的讨论很多,本文仅仅就设计、校审、施工图审查工作中,遇到的问题,诸如单桩竖向承载力问题、桩基的布置问题、液化土层问题、桩身强度问题等进行讨论,作为抛砖引玉,欢迎参与讨论,错误之处敬请指正。

  14. 软土路基中多型桩复合地基的应用研究%Study on the Application of Multi-type-pile Composite Foundation in the Soft Soil Subgrade

    Institute of Scientific and Technical Information of China (English)

    吁燃; 王曙光

    2016-01-01

    为了充分发挥碎石桩与素混凝土桩的优点,将碎石桩与素混凝土桩组合成多型桩复合地基。通过理论计算,分析碎石桩与素混凝土桩组成的多型桩复合地基受力原理。以某高速公路深层软土路基的处理为例,采用多型桩复合地基对该软土路基进行处理,取得了良好的经济效益。%The multi-type-pile composite foundation of gravel pile and plain concrete pile is composed to exert the advantages of crushed stone pile and concrete pile.The load-bearing principle of multi-type-pile composite foundation composed of gravel pile and plain concrete pile is analyzed.Taking an engineering of deep soft soil treatment in the highway for example,the multi-type-pile composite foundation is used,and it achieves good economic performances.

  15. 素混凝土桩复合地基荷载传递机理的试验研究%STUDY ON LOADS TRANSFERRING MECHANISM OF COMPOSITE GROUNDS WITH CONCRETE PILES

    Institute of Scientific and Technical Information of China (English)

    池跃君; 宋二祥; 金淮; 高文新

    2001-01-01

    The distribution and change of axial force of piles and pile friction in composite grounds are very important characters of composite grounds. The axial force of piles was measured by means of in-situ test and on the basis of this the pile friction was worked out. Contrasted with compressible piles and compound piles, the mechanism of concrete piles is different. Contrasted with compressible piles, the loads on concrete piles can be transferred though the whole piles. Contrasted with compound piles, the concrete piles provide negative pile friction around upper piles that leads to the force of piles top is not the maximum. The maximum is at neutrality point. With loads increasing, the negative pile friction decreases and the neutrality point moves upward and part of the negative pile friction transforms into a positive pile friction. It is the pile friction that makes piles bear more loads at the beginning of loading and makes pile friction of lower piles be fully utilized. Thus the interaction between piles and surrounding soil is present in the process of loading. At the same time, the bearing capacity of soil around piles is reinforced.%为研究带有垫层的素混凝土桩复合地基中桩身轴力、桩侧摩阻力的分布及发展过程,设计了一组足比例尺单桩复合地基试验,在桩身内埋设钢弦式应力计测出了桩身轴力,并由此得出桩侧摩阻力。从实测结果与散体桩、无垫层带台单桩的桩身轴力、侧摩阻力分布对比分析可以看出,三者传力机理是不同的。与散体桩相比,素混凝土桩复合地基中荷载沿桩身全长传递。与无垫层带台单桩相比,桩侧摩阻力从加荷开始在桩周上部土层即出现负摩阻,使得桩身轴力最大点不在桩顶而在中性点处。带有垫层的素混凝土桩复合地基中桩侧负摩阻力的大小随荷载加大而变小,同时中性点位置逐渐上移,相当一部分上部土层的摩阻力随着荷载的

  16. 水上木桩成桩质量控制%The DrivingQua lity Co ntrol of Water Timber Pile

    Institute of Scientific and Technical Information of China (English)

    周仲景

    2014-01-01

    The feasibility of water timber pile driving construction was discussed combined with practical engineering , by analyzing the key elements of verticality control on timber pile driving and the implementation of the countermeasures , the bearing capacity of pile testing and settlement observation after construction , it indicated that water timber pile driving construction technique in soft soil layers were applica -ble.%结合工程实例探讨了水上木桩施工的可行性,分析木桩施打时垂直度控制的关键要素及相应对策的实施,并通过成桩后承载力的检测和工后的沉降观测,表明该桩型的水上施工工艺在软土地区是适用的。

  17. Picking up Clues from the Discard Pile

    Science.gov (United States)

    2008-01-01

    As NASA's Phoenix Mars Lander excavates trenches, it also builds piles with most of the material scooped from the holes. The piles, like this one called 'Caterpillar,' provide researchers some information about the soil. On Aug. 24, 2008, during the late afternoon of the 88th Martian day after landing, Phoenix's Surface Stereo Imager took separate exposures through red, green and blue filters that have been combined into this approximately true-color image. This conical pile of soil is about 10 centimeters (4 inches) tall. The sources of material that the robotic arm has dropped onto the Caterpillar pile have included the 'Dodo' and ''Upper Cupboard' trenches and, more recently, the deeper 'Stone Soup' trench. Observations of the pile provide information, such as the slope of the cone and the textures of the soil, that helps scientists understand properties of material excavated from the trenches. For the Stone Soup trench in particular, which is about 18 centimeters (7 inches) deep, the bottom of the trench is in shadow and more difficult to observe than other trenches that Phoenix has dug. The Phoenix team obtained spectral clues about the composition of material from the bottom of Stone Soup by photographing Caterpillar through 15 different filters of the Surface Stereo Imager when the pile was covered in freshly excavated material from the trench. The spectral observation did not produce any sign of water-ice, just typical soil for the site. However, the bigger clumps do show a platy texture that could be consistent with elevated concentration of salts in the soil from deep in Stone Soup. The team chose that location as the source for a soil sample to be analyzed in the lander's wet chemistry laboratory, which can identify soluble salts in the soil. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed

  18. Transient response of piles-bridge under horizontal excitation

    Institute of Scientific and Technical Information of China (English)

    朱斌; 陈仁朋; 陈云敏

    2003-01-01

    Moving ships and other objects drifting on water often impact a bridge' s pile foundations. The mechanical model of the piles-bridge structure under horizontal forcing was established, and a time-domain approach based on Finite-difference Method was developed for analyzing the dynamic response of the piles-bridge structure. For a single pile, good agreement between two computed results validated the present approach.The slenderness ratio of the pile, the pile-soil stiffness ratio and the type of the structure influence the dynamic response of the piles-bridge structure. The computed results showed that the stiffness of the structure determines the dynamic response of the piles-bridge structure under horizontal forcing.

  19. Transient response of piles-bridge under horizontal excitation

    Institute of Scientific and Technical Information of China (English)

    朱斌; 陈仁朋; 陈云敏

    2003-01-01

    Moving ships and other objects drifting on water often impact a bridge's pile foundations. The mechanical model of the piles-bridge structure under horizontal forcing was established, and a time-domain approach based on Finite-difference Method was developed for analyzing the dynamic response of the piles-bridge structure. For a single pile, good agreement between two computed results validated the present approach. The slenderness ratio of the pile, the pile-soil stiffness ratio and the type of the structure influence the dynamic response of the piles-bridge structure. The computed results showed that the stiffness of the structure determines the dynamic response of the piles-bridge structure under horizontal forcing.

  20. In-situ pile detection and analysis of excavation of foundation pit against the influence of uplift piles%基坑开挖对抗拔桩影响的原位桩检测分析

    Institute of Scientific and Technical Information of China (English)

    王朝祥; 张超; 李洪嘉

    2015-01-01

    Excavation of foundation pit can inevitably cause foundation stress field changes and then lead the normal stress of pile-soil interface changes,so as to reduce the bearing capacity of uplift pile and influence the deformation of tension piles. In this essay will detect and analyze the load-carrying properties of uplift pile which at different depth in the sandy region of Shenyang through the test of in-situ pile static load pull-out at the surface and different excavation depth position,some meaningful conclusions are drawn.%基于基坑开挖不可避免地引起地基应力场变化,导致桩—土接触面法向应力发生改变,从而降低抗拔桩承载力,对抗拔桩的变形也产生影响的情况,通过地表和不同开挖深度位置进行原位桩静载荷抗拔试验,对沈阳砂土地区抗拔桩在不同深度时的承载性能进行了原位检测分析,得出了一些有意义的结论。

  1. Application Study of Self-balanced Testing Method on Big Diameter Rock-socketed Piles

    Directory of Open Access Journals (Sweden)

    Qing-biao WANG

    2013-07-01

    Full Text Available Through the technological test of self-balanced testing method on big diameter rock-socketed piles of broadcasting centre building of Tai’an, this paper studies and analyzes the links of the balance position selection, the load cell production and installation, displacement sensor selection and installation, loading steps, stability conditions and determination of the bearing capacity in the process of self-balanced testing. And this paper summarizes key technology and engineering experience of self-balanced testing method of big diameter rock-socketed piles and, meanwhile, it also analyzes the difficult technical problems needed to be resolved urgently at present. Conclusion of the study has important significance to the popularization and application of self-balanced testing method and the similar projects.

  2. Hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

    This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the rheological models and the equations of lubrication. It also presents the numerical approaches used to solve the above equations by finite differences, finite volumes and finite elements methods.

  3. In-situ test and analysis of PHC pipe piles treatment of soft foundation in large-scale refinery%大型炼厂软弱地基PHC管桩现场试验与分析

    Institute of Scientific and Technical Information of China (English)

    马永峰; 周丁恒; 邴启超; 周训军

    2015-01-01

    The soft foundation treatment of large-scale refinery is very complex. In view of this condition, a series of in-situ tests of PHC pipe pile, including low/high strain dynamic test, horizontal and compressive static load test of single pile, were carried out. Based on results of low/high strain test, the quality and completeness of the pile was analyzed. The bearing capacity of single pile was verified by re-sults of high strain test and static load test. And some economical comparison was carried out among various piles of different diameter. The results of static load test showed that the bearing capacity of single pile has reached the standards; when the diameter of PHC pipe pile is 400mm, the ultimate bearing capacity of single pile is affected by pile length greatly;however for PHC pipe pile of 500 mm or 600 mm, the influence from pile length is smaller;the ultimate bearing capacity of single piles that have the same length increases with pile diameter, and the increasing forms are different among piles of various length;the horizontal bearing capacity of PHC pipe pile with concrete core is 50%larger than that of pile without concrete core;In economic terms, the best choice for compressive PHC pipe pile is Ø500 type, the bearing strata of PHC pipe piles should be intensively-weathered to medium-weathered mudstone or completely-weathered to medium-weathered sandstone.%针对大型炼厂工程软弱地基处理的复杂性,开展了PHC管桩的现场试验,完成了PHC管桩施工后的低应变、高应变动力测试及单桩水平、抗压静载荷试验。基于低、高应变测试结果分析了桩身质量及完整性;以高应变测试和静载荷试验结果验证了单桩承载能力;对不同桩径的PHC管桩经济性做了比较分析。静载荷试验结果表明,PHC管桩单桩承载力能达到设计要求;PHC管桩桩径为400 mm时,桩长对单桩极限承载力影响较大,桩径为500 mm或600 mm时,桩长影响较小;同一桩长

  4. THE KINEMATIC AND INERTIAL SOIL-PILE INTERACTIONS: CENTRIFUGE MODELLING

    OpenAIRE

    Chenaf, Nawel; CHAZELAS, Jean-Louis

    2008-01-01

    International audience Piles supporting superstructures undergo with the soil two interactions during an earthquake: the kinematic interaction and the inertial interaction. The kinematic soil-pile interaction is the pile loading by the soil displacement produced by the seismic waves propagating. Inertial superstructure-pile-soil interaction results from forces due to the superstructure actuation by the kinematic interaction. These two interactions are superimposed in seismic events and the...

  5. The Tensile Capacity Of Bored Piles In Frictional Soils

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Andersen, Allan; Damkilde, Lars

    2008-01-01

    Three series of 10 piles each were installed in two different locations. The length of the piles varied from 2 to 6 m and the diameters were 14 and 25 cm. The piles were constructed above the groundwater table using continuous flight augers and the concrete was placed by gravity free fall....... The piles were tested to failure in axial uplift and the load-displacement relations were recorded....

  6. Compressive Experimental Study of Micro Piles by Concreting Method%灌注细石混凝土微型桩基础下压试验研究

    Institute of Scientific and Technical Information of China (English)

    苏荣臻; 邱书清; 鲁先龙

    2012-01-01

    通过现场真型试验,对灌注细石混凝土成桩微型桩基础抗压承载机理及其抗压承载力计算方法进行了研究.试验表明:本次试验条件下,微型桩单桩可看成纯摩擦桩进行抗压承载力计算;微型桩群桩在极限下压荷载作用下,承台底部土体承担荷载比例仅为4.8%,在进行微型桩群桩抗压极限承载力计算时可不考虑承台底土的承载作用;由于承台对下压荷载的重分配,在下压荷载作用下,角桩承力最大,边桩次之,中桩最小;本次试验条件下,微型桩抗压群桩效应系数可取0.8进行计算.%In (his paper, field tests were done to study the compressive bearing mechanism and compressive design method of micropiles. Study shows: in this experimental condition, single micropile can be regarded as friction pile to calculate the compressive bearing capacity; under the ultimate load, the bearing ratio of the soil under the cap of micropile group is only 4. 8% , so calculating the compressive bearing capacity of micropile group cannot take into account the role of subsoil bearing; under compressive load, the bearing load of the angle pile is maximum, the side pile is the second, and the middle pile is minimum; in this experimental condition, the compressive pile group effect coefficient is 0. 8.

  7. A new method of testing pile using dynamic P-S-curve made by amplitude of wave train

    Institute of Scientific and Technical Information of China (English)

    胡毅力; 许峻; 段永康; 许昭永; 杨润海; 赵晋明

    2004-01-01

    A new method of detecting the vertical bearing capacity for single-pile with high strain is discussed in this paper. A heavy hammer or a small type of rocket is used to strike the pile top and the detectors are used to record vibration graphs. An expression of higher degree of strain (deformation force) is introduced. It is testified theoretically that the displacement, velocity and acceleration cannot be obtained by simple integral acceleration and differential velocity when long displacement and high strain exist, namely when the pile phase generates a whole slip relative to the soil body. That is to say that there are non-linear relations between them. It is educed accordingly that the force P and displacement S are calculated from the amplitude of wave train and (dynamic) P-S curve is drew so as to determine the yield points. Further, a method of determining the vertical bearing capacity for single-pile is discussed. A static load test is utilized to check the result of dynamic test and determine the correlative constants of dynamic-static P(Q)-S curve.

  8. A new method of testing pile using dynamic P-S-curve made by amplitude of wave train

    Science.gov (United States)

    Hu, Yi-Li; Xu, Jun; Duan, Yong-Kong; Xu, Zhao-Yong; Yang, Run-Hai; Zhao, Jin-Ming

    2004-11-01

    A new method of detecting the vertical bearing capacity for single-pile with high strain is discussed in this paper. A heavy hammer or a small type of rocket is used to strike the pile top and the detectors are used to record vibration graphs. An expression of higher degree of strain (deformation force) is introduced. It is testified theoretically that the displacement, velocity and acceleration cannot be obtained by simple integral acceleration and differential velocity when long displacement and high strain exist, namely when the pile phase generates a whole slip relative to the soil body. That is to say that there are non-linear relations between them. It is educed accordingly that the force P and displacement S are calculated from the amplitude of wave train and (dynamic) P-S curve is drew so as to determine the yield points. Further, a method of determining the vertical bearing capacity for single-pile is discussed. A static load test is utilized to check the result of dynamic test and determine the correlative constants of dynamic-static P( Q)- S curve.

  9. Stress wave propagation in reinforced concrete piles during driving

    NARCIS (Netherlands)

    Zorn, N.F.

    1983-01-01

    The aim of this report is to give an insight into what happens in a reinforced concrete pile during driving, and to contribute to design requirements for the loading case pile driving. Since the behaviour of stress waves in piles is influenced by a various number of parameters, the fewest of which r

  10. Test Procedure for Axially Loaded Piles in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina

    The test procedure described in the following is used when examining the effects of static or cyclic loading on the skin friction of an axially loaded pile in dense sand. The pile specimen is only loaded in tension to avoid any contribution from the base resistance. The pile dimensions are chosen...

  11. 30 CFR 77.215-3 - Refuse piles: certification.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles: certification. 77.215-3 Section... COAL MINES Surface Installations § 77.215-3 Refuse piles: certification. (a) Within 180 days following written notification by the District Manager that a refuse pile can present a hazard, the person...

  12. 30 CFR 77.215-1 - Refuse piles; identification.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles; identification. 77.215-1 Section... COAL MINES Surface Installations § 77.215-1 Refuse piles; identification. A permanent identification marker, at least six feet high and showing the refuse pile identification number as assigned by...

  13. 30 CFR 77.215-2 - Refuse piles; reporting requirements.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles; reporting requirements. 77.215-2... COAL MINES Surface Installations § 77.215-2 Refuse piles; reporting requirements. (a) The proposed location of a new refuse pile shall be reported to and acknowledged in writing by the District...

  14. 30 CFR 77.215 - Refuse piles; construction requirements.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles; construction requirements. 77.215... COAL MINES Surface Installations § 77.215 Refuse piles; construction requirements. (a) Refuse deposited on a pile shall be spread in layers and compacted in such a manner so as to minimize the flow of...

  15. 30 CFR 77.209 - Surge and storage piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Surge and storage piles. 77.209 Section 77.209... Installations § 77.209 Surge and storage piles. No person shall be permitted to walk or stand immediately above a reclaiming area or in any other area at or near a surge or storage pile where the...

  16. 深开挖卸载条件下坑底群桩受力特性的有限元分析%FINITE ELEMENT ANALYSIS OF LOADING CHARACTERS OF GROUP PILES FOUNDATION DUE TO UNLOADING OF DEEP EXCAVATION

    Institute of Scientific and Technical Information of China (English)

    郝爱玲; 查甫生; 林志月; 崔可锐

    2014-01-01

    大面积的深基坑坑底往往设置密集的工程桩,深开挖导致的土体卸荷回弹作用会对这些工程桩产生强烈的影响。采用ABAQUS软件建立平面有限元分析模型,对深开挖过程中坑底群桩的受力特性进行研究,确定桩顶抬升量、桩土相对位移、桩身轴力和桩侧摩阻力的分布。最后在开挖结束时对各工程桩重新加载,根据Q-s曲线来判断其抗压承载力和抗拔承载力。结果表明,工程桩的承载力与其在基坑平面中的位置有关。%Large scale deep excavation is normally followed by construction of serried engineering piles inside the excavation zone , and unloading and rebound of soil induced by deep excavation have a great influence on those engineering piles .The mechanical characteristics of the pile groups in the bottom of foundation during the process of deep excavation were studied through building plane finite element model by ABAQUS software , and it was determined the lifting extent of pile block, pile-soil relative displacement , pile shaft force, and side friction of pile.Finally, each engineering pile was reloaded when excavation came to an end , then it was made judgments about their compressive bearing capacity and uplift bearing capacity according to the Q-s curve.The results showed that the bearing capacity of the engineering piles was related to their positions in the foundation excavation plane .

  17. Reduction in Rebound of Concrete Piles Driven into Clays by Coating Pile Surface with Titanium Dioxide Nanoparticles

    OpenAIRE

    Amalia, Nadya; Asri, Asifa; Rokhmat, Mamat; Sutisna; Abdullah, Mikrajuddin

    2015-01-01

    Using a model for concrete piles driven into clays, we compared penetration depths between uncoated piles and piles coated with titanium dioxide (TiO2) nanoparticles. The behavior of surfaces coated with TiO2 changes to superhydrophilic, enabling water molecules to penetrate inside the clay pores. The attraction suppresses or reduces the compression of water inside the clay pores. The absence of bulk pressure from water causes the pile not to bounce (backward movement after striking). Contrar...

  18. Full size testing of sheet pile walls

    NARCIS (Netherlands)

    Kuilen, J.W.G. van de; Linden, M.L.R. van der; Katsma, H.; Stolle, P.

    1996-01-01

    Azobé (Lophira alata) is widely used in timber sheet pile walls in the Netherlands. The boards in these walls are coupled and therefore load-sharing can be expected. A simulation model based on the finite element method DIANA (DIANA, 1992) was developed and load-sharing could be calculated. To check

  19. Underwater noise generated by offshore pile driving

    NARCIS (Netherlands)

    Tsouvalas, A.

    2015-01-01

    Anthropogenic noise emission in the marine environment has always been an environmental issue of serious concern. In particular, the noise generated during the installation of foundation piles is considered to be one of the most significant sources of underwater noise pollution. This is mainly attri

  20. On the Modelling of Pile Installation

    NARCIS (Netherlands)

    Dijkstra, J.

    2009-01-01

    This thesis introduces two different types of physical model tests to investigate the stress and density change in the soil during installation of a jacked pile as well as two numerical modelling approaches to model the same process in a finite element code capable of large deformations.

  1. 40 CFR 264.554 - Staging piles.

    Science.gov (United States)

    2010-07-01

    ... operations as long as they are intended to prepare the wastes for subsequent management or treatment. (2) (b... waste no longer meets the definition of ignitable or reactive under § 261.21 or § 261.23 of this chapter... determine that continued operation of the staging pile: (i) Will not pose a threat to human health and...

  2. Literature review Quasi-static and Dynamic pile load tests: Primarily report on non-static pile load tests

    NARCIS (Netherlands)

    Huy, N.Q.

    2010-01-01

    Pile testing, which plays an importance role in the field of deep foundation design, is performed by static and non-static methods to provide information about the following issues: (Poulos, 1998) - The ultimate capacity of a single pile. - The load-displacement behavior of a pile. - The performance

  3. Pile – Soil Interaction during Vibratory Sheet Pile Driving : a Full Scale Field Study

    OpenAIRE

    Guillement, Claire

    2013-01-01

    Urban construction sites require strict control of their environmental impact, which, for vibratory sheet pile driving, can include damage to nearby structures due to ground vibrations. However, the lack of knowledge concerning the generation of soil vibrations makes the prediction of ground vibration levels difficult. This MSc. thesis in particular, focuses on a crucial link in the vibration transfer chain: the sheet pile – soil interface, which is also one of the least documented. The aim o...

  4. Tooling Converts Stock Bearings To Custom Bearings

    Science.gov (United States)

    Fleenor, E. N., Jr.

    1983-01-01

    Technique for reworking stock bearings saves time and produces helicopter-rotor bearings ground more precisely. Split tapered ring at one end of threaded bolt expands to hold inside of inner race bearing assembly; nut, at other end of bolt, adjusts amount of spring tension. Piece of hardware grasps bearing firmly without interfering with grinding operation. Operation produces bearing of higher quality than commercially available bearings.

  5. 现浇X形群桩竖向抗拔特性及影响因素分析%Vertical Uplift Capacity Characteristics and Influence Factor Analysis of Cast-in-situ X-section Reinforced Concrete Pile Group

    Institute of Scientific and Technical Information of China (English)

    孔纲强; 丁选明; 陈育民; 杨贵

    2012-01-01

    Based on Nanjing Sewage Treatment Plant soft ground improvement engineering, field tests of X-section cast-in-situ reinforced concrete pile (referred to as XCC pile) under vertical uplift bearing capacity were carried out, in which the relation curves of load-displacement were measured. Numerical models for XCC single pile and pile group under uplift load were built by using FLAC3D software. The simulation result was compared with single pile field test result. Comparing analysis with the bearing capacity of circular piles under uplift load was carried out. Then, the mechanical properties of XCC pile group which were influenced by pile length, pile-soil fraction coefficient and pile position were analyzed and discussed. The study results show that the vertical uplift bearing capacity of XCC pile is relatively equals to that of circular pile with the same out-diameters, nearly 17. 4% larger than that of circular pile with the same concrete volumes.%结合南京某污水处理厂软基处理工程,开展了现浇X形钢筋混凝土桩(简称X形桩)单桩竖向抗拔承载力现场试验,测得了荷载-位移关系曲线;基于FLAC3D软件建立了竖向上拔荷载作用下X形单桩、群桩特性分析的数值模型,并与现场单桩抗拔试验结果进行对比分析;比较研究了与等效圆形截面桩抗拔承载力的差异,并分析了基桩长度、桩-土摩擦因数以及基桩位置等因素对X形群桩力学特性的影响规律.研究结果表明:X形桩竖向抗拔承载力与其等外包直径的圆形截面桩承载力相近,较等混凝土用量的圆形截面桩承载力提高了近17.4%.

  6. NONLINEAR DYNAMICAL CHARACTERISTICS OF PILES UNDER HORIZONTAL VIBRATION

    Institute of Scientific and Technical Information of China (English)

    HU Yu-jia; CHENG Chang-jun; YANG Xiao

    2005-01-01

    The pile-soil system is regarded as a visco-elastic half-space embedded pile. Based on the method of continuum mechanics, a nonlinear mathematical model of pilesoil interaction was established-a coupling nonlinear boundary value problem. Under the case of horizontal vibration, the nonlinearly dynamical characteristics of pile applying the axis force were studied in horizontal direction in frequency domain. The effects of parameters, especially the axis force on the stiffness were studied in detail. The numerical results suggest that it is possible that the pile applying an axis force will lose its stability. So, the effect of the axis force on the pile is considered.

  7. The Settlement Behavior of Piled Raft Interaction in Undrained Soil

    DEFF Research Database (Denmark)

    Ghalesari, Abbasali Taghavi; Barari, Amin; Amini, Pedram Fardad;

    2013-01-01

    , the behavior of a piled raft on undrained soil is studied based on a series of parametric studies on the average and differential settlement of piled raft using three-dimensional finite element analysis. The settlement behavior is found to be dependent on the number of piles and raft thickness.......Offshore piled raft foundations are one of the most commonly used foundations in offshore structures. When a raft foundation alone does not satisfy the design requirements, the addition of piles may improve both the ultimate load capacity and the settlement performance of the raft. In this paper...

  8. Seismic Response Analysis of Portal Water Injection Sheet Pile

    Institute of Scientific and Technical Information of China (English)

    WANG Yuanbin; GUO Haiyan; ZHANG Chunhui

    2007-01-01

    To further the study on the newly developed portal water injection sheet pile under static loads, in this paper, by adopting the nonlinear calculation module of FEM software ANSYS, a model for the interaction between the soil and the sheet piles is set up,and the seismic response analysis for this type of space-retaining structure is performed. The effects of the embedded depth and the distance between the front pile and the back pile on the dynamic characteristics of the portal water injection sheet pile are studied.

  9. 竖向荷载下群桩-土-承台相互作用数值分析%Numerical analysis of interaction of pile group-soil-raft under vertical load

    Institute of Scientific and Technical Information of China (English)

    杜家庆; 杜守继; 赵丹蕾; 唐文勇

    2013-01-01

    Besides the interaction of the multiple stress superposition from piles shaft friction, pile bottom resistance and contact stress between low caps and soil, the clamping action makes the cap-pile-soil interaction more complicated in pile foundation with large pile diameter and small spacing. 3D finite difference program is employed to evaluate the pile-soil-cap interaction with the change of vertical load, while the pile spacing and pile diameter remain constant in the analysis procedure. Analysis is carried out to explain the interaction of cap-pile-soil from the following aspects such as the lateral friction of soil in each layer, load on the top of characteristic piles, load-settlement relationship, vertical displacement of soil between piles, etc. The results show that: the clamping action on the upper soil among piles will decrease, and the pile shaft friction in the upper part will increase when the load exceeds 117.8 MN which is slightly larger than Pu/2 (Pu means ultimate bearing capacity of piles group); the lower part of pile shaft friction shows a trend of decrease due to the influence of the multiple stress superposition, and the decrease trend in characteristic piles has different influence scope; the load, which makes settlement of piles group achieve 5% of pile diameter, can be regarded as the vertical ultimate bearing capacity of piles group, and it is reasonable; when the ratio of piles group’s settlement to pile diameter exceeds 1%, the proportion of the load carried by piles decreases because of the cap contribution.%  在大桩径、小桩距的群桩条件下,不仅有来自桩侧、桩端和承台传递的多重应力叠加,还有群桩对桩间土的夹持作用影响,桩-土-承台之间作用更加复杂。用有限差分软件模拟固定桩距、桩径,变化竖向荷载下桩-土-承台的相互作用。从各层土的侧摩阻力、不同位置桩的桩顶荷载、荷载-沉降关系、桩间土体位移等方面的计算

  10. Numerical analysis of kinematic soil—pile interaction

    Science.gov (United States)

    Castelli, Francesco; Maugeri, Michele; Mylonakis, George

    2008-07-01

    In the present study, the response of singles pile to kinematic seismic loading is investigated using the computer program SAP2000@. The objectives of the study are: (1) to develop a numerical model that can realistically simulate kinematic soil-structure interaction for piles accounting for discontinuity conditions at the pile-soil interface, energy dissipation and wave propagation; (2) to use the model for evaluating kinematic interaction effects on pile response as function of input ground motion; and (3) to present a case study in which theoretical predictions are compared with results obtained from other formulations. To evaluate the effects of kinematic loading, the responses of both the free-field soil (with no piles) and the pile were compared. Time history and static pushover analyses were conducted to estimate the displacement and kinematic pile bending under seismic loadings.

  11. Friction effects on lateral loading behavior of rigid piles

    DEFF Research Database (Denmark)

    Zania, Varvara; Hededal, Ole

    2012-01-01

    The adequacy of the p -y curves used in the current practice for the design of rigid pile foundations with large diameter, like in the case of monopile foundations of offshore wind turbines, has been widely questioned. The current study aims at analyzing the lateral behavior of rigid piles, while...... taking into account the shear frictional resistance along the pile. For this purpose efficient three dimensional finite element models of different diameter have been developed. The increase of the side friction and of the diameter of the pile is shown to alter the failure pattern and increase...... the lateral capacity of the pile. The obtained p - y curves demonstrate the importance of the aforementioned parameters in the design of rigid piles, as the reduction of friction along the interface reduces not only the ultimate load but also the stiffness of the soil-pile response. Read More: http...

  12. The Strength of Rubble Pile Asteroids

    Science.gov (United States)

    Scheeres, D. J.; Sanchez, P.

    2012-12-01

    The rubble pile hypothesis for small asteroids in the Near Earth and Main Belt populations have been driven by several factors, including the observed high porosity of those bodies whose mass have been measured, the evident limitation on spin rate of asteroids larger than ~500 meters, and direct observation of the surface morphology of these bodies. Given these observations, it has been presumed that small asteroids should evolve as if they were cohesionless collections of grains. Detailed geophysical analysis of these bodies by Holsapple (Icarus 2010) show that cohesionless bodies will evolve under the addition of angular momentum by the YORP effect into more distended and, paradoxically, more slowly rotating bodies. Additional analysis in Holsapple (Icarus 2007) has shown that cohesional strength within a rubble pile could strengthen a collection of grains to the point where they could sustain rapid rotation. In our current talk we use the above as a starting point and incorporate new observations of the asteroid morphology driven by recent analysis of asteroid Itokawa by the Hayabusa science team and research on the mechanics of grains in the space environment (Scheeres et al. 2010). Analysis of images of Itokawa determined a measured size distribution of 1/d^3 for larger grains on asteroid Itokawa (Michikami et al., Earth Planets Space, 60, 13-20, 2008). Analysis of the sample shows the presence of micron sized dust on that asteroid's surface (Tsuchiyama et al., Science 333, 1125, 2011). Combining these observations provides a global indication of grain distribution within rubble piles. Even assuming a less steep distribution of 1/d^2 for dust grains smaller than 1 mm in size, the interior of Itokawa should still be dominated by the finest dust grains, with the mean grain size equal to ~ twice the smallest grain in the distribution. One implication of this result is that fines are present on the surface of the rubble pile Itokawa and thus should be distributed

  13. A computational model of pile vertical vibration in saturated soil based on the radial disturbed zone of pile driving

    Science.gov (United States)

    Li, Qiang; Shi, Qian; Wang, Kuihua

    2010-06-01

    In this study, a simplified computational model of pile vertical vibration was developed. The model was based on the inhomogeneous radial disturbed zone of soil in the vicinity of a pile disturbed by pile driving. The model contained two regions: the disturbed zone, which was located in the immediate vicinity of the pile, and the undisturbed region, external to the disturbed zone. In the model, excess pore pressure in the disturbed zone caused by pile driving was assumed to follow a logarithmic distribution. The relationships of stress and strain in the disturbed zone were based on the principle of effective stress under plain strain conditions. The external zone was governed by the poroelastic theory proposed by Biot. With the use of a variable separation method, an analytical solution in the frequency domain was obtained. Furthermore, a semi-analytical solution was attained by employing a numerical convolution method. Numerical results from the frequency and time domain indicated that the equivalent radius of the disturbed zone and the ratio of excess pore pressure had a significant effect on pile dynamic response. However, actual interactions between pile and soil will be weaker due to the presence of the radial disturbed zone, which is caused by pile driving. Consequently, the ideal undisturbed model overestimates the interaction between pile and soil; however, the proposed model reflects the interaction of pile and soil better than the perfect contact model. Numerical results indicate that the model can account for the time effect of pile dynamic tests.

  14. The mechanical response of piles with consideration of pile-soil interactions under a periodic wave pressure

    Institute of Scientific and Technical Information of China (English)

    朱峰; 徐卫亚; 王环玲

    2014-01-01

    The pile-soil interaction under wave loads is an extremely complex and difficult issue in engineering. In this study, a physical model test is designed based on the principle of the gravity similarity to obtain time histories of wave forces of unsteady regular waves, and to measure the magnitude and the distribution of wave forces acting on the piles. A numerical model and relevant numerical methods for the pile-soil contact surface are adopted based on the principles of elastic dynamics. For a practical project, the time histories of wave forces on the piles are obtained through physical model tests. The deformations of the piles in the pile-soil interactions and the distribution of the bending moment on the piles are studied. It is shown that, with the increase of the period of wave pressures, the absolute value of the horizontal displacement of the piles increases, the embedment depth of the piles increases, and the scope of influence of soils increases. The change of the bending moment on the piles is consistent with that of its theoretical results, and the proposed numerical method can very well simulate the properties of the piles.

  15. DYNAMIC SOUNDING AND BEARING CAPACITY OF PILES / ДИНАМИЧЕСКОЕ ЗОНДИРОВАНИЕ И НЕСУЩАЯ СПОСОБНОСТЬ СВАЙ

    Directory of Open Access Journals (Sweden)

    Chichkin A. F. / Чичкин Александр Федорович

    2013-11-01

    Full Text Available The article is devoted to the analysis of the results of dynamic sounding on construction platforms with various soil conditions in comparison to the tests of piles by static loading. The authors provide the comparison of the results of tests and calculations, on the basis of which the conclusion about competitiveness of dynamic sounding is made, and used in Penza city to set trial pile length with dynamic testing and statistics sounding / Анализируются результаты динамического зондирования на площадках строительства с различными грунтовыми условиями в сопоставлении с испытаниями свай статической нагрузкой. Приводятся сравнительные результаты испытаний и расчетов, на основании чего делается вывод о конкурентоспособности способа динамического зондирования, применяемого в г. Пензе для назначения длины пробных свай, с динамическими испытаниями свай и статическим зондированием

  16. Application of post-pile grouting technique to composite building of the Huaibei Huasong commercial plaza%桩基后注浆技术在淮北华松商业广场综合楼中的应用

    Institute of Scientific and Technical Information of China (English)

    李飞蛟

    2012-01-01

      淮北华松商业广场综合楼场地地深部局部岩溶发育,主楼柱距大,要求桩基承载力大,通过对桩端持力层的后注浆处理,既避开岩溶,又满足承载力、变形要求。%  Karst is locally developed in the depth of the site of composite building of Huaibei Huasong commercial pla-za. The major building pillars are widely spaced and require piles to have great bearing capacity. Post-pile grouting was performed to the pile-end bearing layer, not only avoiding karst, but also meeting the demand of bearing capacity and deformation.

  17. NONLINEAR STATIC CALCULATION MODEL AND PSEUDO-STATIC TEST OF PILE GROUP BRIDGE FOUNDATIONS%桥梁群桩基础非线性静力计算模型及拟静力试验研究

    Institute of Scientific and Technical Information of China (English)

    张永亮; 陈兴冲; 孙建飞

    2013-01-01

    Horizontal bearing characteristics of bridge pile foundations can be analyzed by using linear elastic subgrade reaction method(m-method) when displacement of pile foundation is generally smaller. However, displacement of pile foundations is often larger under the effect of strong earthquakes. In order to understand the horizontal bearing capacity and deformation characteristics of pile foundations considering nonlinear behaviors of pile shaft and subsoil,a model of pile foundations is constructed. Failure mechanism,bearing capacity, deformation characteristics and hysteresis characteristics of pile foundations are studied by using pseudo-static test. A nonlinear static calculation model of pile group foundations is put forward under horizontal load. The elastoplasticity of pile shafts in variable axial loads is simulated by distributed PMM plastic hinge;and nonlinearity of subsoil is simulated by the curves of p-y,t-z and q-z,respectively,which have been given in the code of American API;where p is horizontal soil resistance at lateral of pile shaft;y is horizontal displacement;t is vertical frictional resistance around piles shaft;q is vertical bearing resistance at pile tip;z is vertical relative displacement of interface between pile and soil. The results show that:(1) The numerical results are in good agreement with those obtained from experiments. (2) Hysteretic characteristics of pile foundations can be simulated using Clough degradation bilinear model. (3) Weak positions of pile shaft are 0-4 times around the radius of pile below pile top. The results can provide references for evaluating seismic performance of bridge pile foundation using capacity spectrum method.%线弹性地基反力法(m 法)仅适用于正常使用时桥梁桩基础变位较小的情况,但在强震作用下基础的变位较大。为了研究桩基础在地基土及桩身进入非线性状态下的水平承载能力及变形特性,通过群桩基础缩尺比例模型,采用拟

  18. 不同运动方向两桩间桩-土-桩相互作用%PILE-SOIL-PILE INTERACTION BETWEEN TWO PILES MOVING ALONG DIFFERENT DIRECTIONS

    Institute of Scientific and Technical Information of China (English)

    孔令刚; 樊继营; 陈仁朋; 陈云敏

    2013-01-01

    Both centrifuge modeling and numerical simulation are employed to investigate pile-soil-pile interaction between two adjacent piles with pile spacing of 3 times pile diameter moving in different directions. The influence of pile spacing,internal friction angle of sand,and different displacements of the leading and trailing piles on reduction factor are also analyzed based on numerical results. It is found that pile-soil-pile interaction is significant in two adjacent piles undergoing different movement directions. The reduction factor of the trail pile is not larger than that of the leading one in the investigated two cases. It is also found that reduction factors for the leading and trail piles almost linearly increase as pile spacing varies from 3 times pile diameter to 5 times and almost keep constant with internal friction angle. In addition,loading mode has certain effect on reduction factors of the two piles.%通过离心模型试验和数值模拟手段研究不同运动方向下桩间距为3倍桩径的两桩间相互作用规律,并分析桩间距、土体内摩擦角以及不同桩头位移对前、后桩折减系数的影响。通过分析表明,沿不同方向运动的两桩间存在明显的桩-土-桩相互作用,该相互作用效果与桩所在位置有明显关系,前桩的相互作用折减系数明显大于于后桩;当桩间距在3~5倍桩径范围内,前、后桩折减系数随桩间距近似线性变化;砂土内摩察角对折减系数的影响可以忽略。另外,不同加载方式对两桩的折减系数也有一定影响。

  19. Numerical modeling of an advancing hydraulically-driven pile in sand

    Institute of Scientific and Technical Information of China (English)

    Meen-wah GUI

    2011-01-01

    The penetration of a model pile through sand was investigated via a numerical analysis. Data from nine triaxial compression tests on dense specimens at different stress levels was generalized and used to create an empirical non-linear plastic hardening stress-strain relation for use in the analysis. As the computer program used is capable of large displacement analyses in radial symmetry, we expected that the analysis would easily reproduce the tip resistance penetration profile of the model pile in sand of known density and stress. However, initial attempts led to over-prediction. Successful analyses required both successive reformations of the mesh and the complete elimination of the dilatant peak in soil strength, which is naturally eliminated under large confining stress directly beneath the advancing tip, and that soil in the far-field had strained insufficiently to reach peak strength. Thus, the soil around the shaft must have been sheared to a critical state as it flowed past the tip. The hypothesis that the resistance to displacement piles in sand is mainly a function of the deformability of the sand was again proven, and the use of peak strength in the traditional bearing capacity formulae was found to be inappropriate. Independent investigation in this direction is needed to quantify the hypothesis.

  20. Research on loading performance test of super-long PHC pipe pile%超长PHC管桩承压性能试验研究

    Institute of Scientific and Technical Information of China (English)

    刘运庚

    2012-01-01

    According to the compressive static loading experiment on six PHC super-long pipe pile,the paper analyzes the compressive static performance of the PHC pipe pile,adopts the high strain dynamic testing method,concludes the side friction resistance and end-bearing friction at different soil layers,proves by the research result that the single-pile compressive loading capacity varies along with the different bearing stratums,the single ultimate loading capacity,the end-bearing friction,and its total friction increase with the addition of the pile length,and concludes the average of the recovery coefficient of the loading capacity(recovering coefficient of friction of soil around piles) is 1.13 according to the comparison between the test result from the pipe pile redriving and the driving tests.%根据6个PHC超长管桩的抗压静载试验,分析了PHC管桩的抗承载性能,采用高应变检测方法,得到了不同土层的侧摩阻力及桩端阻力值,研究结果表明:单桩抗压承载力因持力层的不同而不同;随着桩长的增加,单桩极限承载力、桩端阻力及其所占总阻力的比例相应增加;根据管桩复打和初打检测结果的比较,得到承载力恢复系数(桩周土阻力恢复系数)平均值为1.13。

  1. Are cometary nuclei primordial rubble piles?

    Science.gov (United States)

    Weissman, P. R.

    1986-01-01

    Whipple's icy conglomerate model for the cometary nucleus has had considerable sucess in explaining a variety of cometary phenomena such as gas production rates and nongravitational forces. However, as discussed here, both observational evidence and theoretical considerations suggest that the cometary nucleus may not be a well-consolidated single body, but may instead be a loosely bound agglomeration of smaller fragments, weakly bonded and subject to occasional or even frequent disruptive events. The proposed model is analogous to the 'rubble pile' model suggested for the larger main-belt asteroids, although the larger cometary fragments are expected to be primordial condensations rather than collisionally derived debris as in the asteroid case. The concept of cometary nuclei as primordial rubble piles is proposed as a modification of the basic Whipple model, not as a replacement for it.

  2. FORECASTING PILE SETTLEMENT ON CLAYSTONE USING NUMERICAL AND ANALYTICAL METHODS

    Directory of Open Access Journals (Sweden)

    Ponomarev Andrey Budimirovich

    2016-06-01

    Full Text Available In the article the problem of designing pile foundations on claystones is reviewed. The purpose of this paper is comparative analysis of the analytical and numerical methods for forecasting the settlement of piles on claystones. The following tasks were solved during the study: 1 The existing researches of pile settlement are analyzed; 2 The characteristics of experimental studies and the parameters for numerical modeling are presented, methods of field research of single piles’ operation are described; 3 Calculation of single pile settlement is performed using numerical methods in the software package Plaxis 2D and analytical method according to the requirements SP 24.13330.2011; 4 Experimental data is compared with the results of analytical and numerical calculations; 5 Basing on these results recommendations for forecasting pile settlement on claystone are presented. Much attention is paid to the calculation of pile settlement considering the impacted areas in ground space beside pile and the comparison with the results of field experiments. Basing on the obtained results, for the prediction of settlement of single pile on claystone the authors recommend using the analytical method considered in SP 24.13330.2011 with account for the impacted areas in ground space beside driven pile. In the case of forecasting the settlement of single pile on claystone by numerical methods in Plaxis 2D the authors recommend using the Hardening Soil model considering the impacted areas in ground space beside the driven pile. The analyses of the results and calculations are presented for examination and verification; therefore it is necessary to continue the research work of deep foundation at another experimental sites to improve the reliability of the calculation of pile foundation settlement. The work is of great interest for geotechnical engineers engaged in research, design and construction of pile foundations.

  3. Soil Structure Interaction in Energy Piles

    OpenAIRE

    Chen, Diming

    2016-01-01

    This study focuses on developing an improved thermo-mechanical soil-structure interaction (i.e., load transfer) analysis to assess the axial strains, stresses, and displacements during thermo-mechanical loading of energy piles in different soils having different end restraint boundary conditions. This study builds on established analyses by (i) incorporating an algorithm to identify the location of the point of zero displacement (i.e., the null point) during changes in temperature, (ii) addin...

  4. Underwater noise generated by offshore pile driving

    OpenAIRE

    Tsouvalas, A.

    2015-01-01

    Anthropogenic noise emission in the marine environment has always been an environmental issue of serious concern. In particular, the noise generated during the installation of foundation piles is considered to be one of the most significant sources of underwater noise pollution. This is mainly attributed to the recent developments in the offshore wind industry. To meet the increasing demand for energy from renewable resources, a large number of offshore wind farms are planned to be constructe...

  5. CENTRIFUGAL VIBRATION TEST OF RC PILE FOUNDATION

    Science.gov (United States)

    Higuchi, Shunichi; Tsutsumiuchi, Takahiro; Otsuka, Rinna; Ito, Koji; Ejiri, Joji

    It is necessary that nonlinear responses of structures are clarified by soil-structure interaction analysis for the purpose of evaluating the seismic performances of underground structure or foundation structure. In this research, centrifuge shake table tests of reinforced concrete pile foundation installed in the liquefied ground were conducted. Then, finite element analyses for the tests were conducted to confirm an applicability of the analytical method by comparing the experimental results and analytical results.

  6. 扩顶CFG桩在大型油罐地基处理中的应用%Application of Top-Extended CFG Pile to Foundation Treatment of Large Oil Tank

    Institute of Scientific and Technical Information of China (English)

    盛志战; 苏振兴; 陈彬; 曹建方

    2013-01-01

    扩顶CFG桩复合地基是在常规CFG桩复合地基基础上发展起来的一种新的地基处理形式,利用了扩顶的荷载收集效应,充分发挥桩体高承载力的优势及桩间土的承载和变形协调能力.本文简要介绍了扩顶CFG桩复合地基的作用机理及油罐地基处理的要求和特点.针对江苏某大型油罐基底为淤泥质软土的特殊情况,采用“山皮石桩+ CFG桩+桩帽+加筋垫层”的复合形式,桩帽和加筋垫层的共同作用,充分发挥桩体高承载力的优势,创造性的将山皮石桩+扩顶CFG桩的多桩型复合地基处理方式应用于大型油罐地基处理中,为大型油罐软土地基处理提供了一种新的思路.%The top-extended CFG pile composite foundation is a new foundation treatment technique based on the conventional CFG pile composite foundation. It can make full use of the "load collecting" function and high bearing capacity of top-extended piles, and the bearing capacity and the deformation compatibility of soil between piles. This paper introduces the mechanism of the top-extended CFG pile composite foundation and the requirements and characteristics of oil tank foundation treatment. According to the foundation for silt soil of a large oil tank in Jiangsu province, it can give full play to the advantages of high bearing capacity of CFG pile, using the "gravel pile + CFG pile + pile cap + reinforced cushion" compound form , as well as pile caps and reinforced cushion worked together. The gravel pile and top-extended CFG pile composite foundation is creatively applied to the foundation treatment of large oil tanks and provides new thinking for yhe soft soil foundation treatment of large oil tanks.

  7. Hydrodynamic Behavior of Curtainwall-Pile Breakwaters

    Institute of Scientific and Technical Information of China (English)

    O.Nejadkazem; A.R.M.Gharabaghi

    2012-01-01

    A numerical model is developed that can predict the interaction of regular waves normally incident upon a curtainwall-pile breakwater; the upper part of which is a vertical wall and the lower part consists of an array of vertical piles.The numerical model is based on an eigenfunetion expansion method,and utilizes a boundary condition nearby the vertical piles that accounts for wave energy dissipation.Numerical solution comprises a finite number of terms,which is a superposition of propagating waves and a series of evanescent waves.The modeling is validated by comparison with previous experimental studies and overall agreement between measurement and calculation is fairly good.The numerical results are related to reflection,transmission,and dissipation coefficient; wave run-up,wave force,and wave overturning moment are also presented.Effect of porosity,relative draft,and relative water depth are discussed; the choice of suitable range of them is described.The relative draft is more effective for shallow water waves.Model shows decrease in relative draft and leads to reduction of relative wave force,overturning moment,and nunup.It is shown that curtainwallpile breakwaters can operate both effectively and efficiently in the range of relative draft between 0.15 and 0.75.The range 0.5 to 0.2 is also recommended for porosity.

  8. Soil Plug Effect Prediction and Pile Driveability Analysis for Large-Diameter Steel Piles in Ocean Engineering

    Institute of Scientific and Technical Information of China (English)

    LIU Run; YAN Shu-wang; LI Zhi-hua

    2009-01-01

    Long steel piles with large diameters have been more widely used in the field of ocean engineering.Owing to the pile with a large diameter,soil plug development during pile driving has great influences on pile driveability and beating capacity.The response of soil plug developed inside the open-ended pipe pile during the dynamic condition of pile-driving is different from the response under the static condition of loading during service.This paper addresses the former aspect.A numerical procedure for soil plng effect prediction and pile driveability analysis is proposed and described.By taking into consideration of the pile dimension effect on side and tip resistance,this approach introduces a dimensional coefficient to the conventional static equilibrium equations for the plug differential unit and proposes an improved static equity method for the plug effect prediction.At the same time,this approach introduces a simplified model by use of one-dimensional stress wave equation to simulate the interaction between soft ping and pile inner wall.The proposed approach has been applied in practical engineering analyses.Results show that the calculated plug effect and pile driveability based on the proposed approach agree well with the observed data.

  9. Mechanical properties of prestressed high-intensity concrete pile and pile caps combined%预应力高强混凝土管桩-承台组合体受力性能

    Institute of Scientific and Technical Information of China (English)

    李艳艳; 李泽高; 李和庆; 赵雄

    2015-01-01

    对5个预制桩身与承台组合体试件进行低周反复试验,分析构件的破坏形态、承载力及延性、锚固钢筋的受力,研究预制桩身与承台锚固钢筋的不同锚固形式对试件受力性能的影响.结果表明:通过连接板焊接锚固钢筋的试件,倾角锚固钢筋能延缓试件裂缝的发展,提高试件的承载能力;在桩身内安放钢筋笼并深入承台的锚固钢筋可明显改善管桩-承台组合体试件的整体性,提高组合体试件的承载能力、延性,改善组合体试件的变形能力,且斜角锚固钢筋试件的承载能力优于直角试件.%5 specimens of prefabricated pile combined with pile caps are tested under low cycle reciprocating loading.The failure patterns,the bearing capacity and the ductility,the forces in anchoring reinforcing bars,as well as the influence of different forms of the precast pile and pile cap anchoring reinforcing bars on the mechanical properties of the specimen are studied.It is shown that by anchoring reinforced connecting plate welded specimens,the inclined anchoring reinforcing bars can play a role in delaying the growth of cracks,increasing the beating capacity of the specimen.The specimens with the pile body and the anchoring reinforcing bars can significantly improve the integrity of the pile cap assembly of the specimen and increase the bearing capacity,the ductility,and the deformation ability,and the bearing capacity of the anchoring reinforcing bars of oblique angle is better than that of the rectangular specimens.

  10. Impedance function of a group of vertical piles

    International Nuclear Information System (INIS)

    Impedance and transfer functions of a group of vertical piles located in any desired configuration in plan in a horizontally stratified soil layer are derived. Hysteretic and radiation damping are accounted for. The method separates the piles and the soil, introducing unknown interaction forces. The total flexibility matrix of the soil is constructed, superposing the (complex) flexibility coefficients caused by the interaction forces of a single pile only. The dependence of the impedance and transfer functions on the oscllating frequency for foundations with different numbers of piles is investigated. Pile-soil-pile interaction is shown to be very important for all modes of vibration. The procedure is used in the seismic analysis of a reactor building. (Author)

  11. SCOUR MITIGATION AT BRIDGE PIERS USING SACRIFICIAL PILES

    Institute of Scientific and Technical Information of China (English)

    M. Anisul HAQUE; Md. Munsur RAHMAN; G.M. Tarekul ISLAM; M. Asad HUSSAIN

    2007-01-01

    To mitigate scour around bridge piers, sacrificial piles are economic method where natural processes are involved. The arrangement should be such that scoured materials from the sacrificial piles should have enough volume to fill the scour hole created upstream of the pier in such a way that sediments are trapped inside the scour hole. This concept differs from earlier study made with sacrificial piles that mainly deals to reduce the strength of horseshoe vortex. To determine the effect of sacrificial piles for scour mitigation, alternative arrangements of piles were tested in front of a rectangular pier under clear-water condition and found that when the group of piles is placed at a distance of twice the projected width of the pier, for which percentage of blockage of the pier width is 60%, the scour volume can be reduced upto 61% while the maximum scour depth can be reduced upto 50%.

  12. Settlement calculation for long-short composite piled raft foundation

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-hua; ZHANG Ling; YANG Ming-hui

    2006-01-01

    The mechanism of long-short composite piled raft foundation was discussed. Assuming the relationship between shear stress and shear strain of the surrounding soil was elasto-plastic, shear displacement method was employed to establish the different explicit relational equations between the load and the displacement at the top of pile in either elastic or elasto-plastic period. Then Mylonakis & Gazetas model was introduced to simulate the interaction between two piles or between piles and soil. Considering the effect of cushion, the flexible coefficients of interaction were provided. With the addition of a relevant program, the settlement calculation for long-short composite piled raft foundation was developed which could be used to account for the interaction of piles,soil and cushion. Finally, the calculation method was used to analyze an engineering example. The calculated value of settlement is 10.2 mm, which is close to the observed value 8.8 mm.

  13. In-Pile Thermal Conductivity Measurement Methods for Nuclear Fuels

    OpenAIRE

    Fox, Brandon S.

    2010-01-01

    Measuring nuclear fuel thermal conductivity in-pile can provide much needed data for understanding fuel performance during irradiation and yield thermophysical property data needed for simulation codes and fuel databases. The objective of this research is to develop and compare two in-pile thermal conductivity methods in a laboratory setting using surrogate fuel materials. A steady-state radial heat flow method was investigated to understand its viability as an in-pile steady-state thermal...

  14. Influence of heave reducing piles on ground movements around excavations

    OpenAIRE

    McNamara, A M

    2001-01-01

    The research concerns the influence of piles, installed beneath deep excavations, as a means of reducing movements in the surrounding ground. The work focussed on the use of piles installed as a part of top down basement construction, a technique used in conjunction with deep excavations in urban areas. The investigations sought to explore the effectiveness of bored piles as a means of enhancing the stiffness of the soil beneath the excavation and so reducing the spread of movements to the su...

  15. Environmentally Friendly Solution to Ground Hazards in Design of Bridges in Earthquake Prone Areas Using Timber Piles

    Science.gov (United States)

    Sadeghi, H.

    2015-12-01

    Bridges are major elements of infrastructure in all societies. Their safety and continued serviceability guaranties the transportation and emergency access in urban and rural areas. However, these important structures are subject to earthquake induced damages in structure and foundations. The basic approach to the proper support of foundations are a) distribution of imposed loads to foundation in a way they can resist those loads without excessive settlement and failure; b) modification of foundation ground with various available methods; and c) combination of "a" and "b". The engineers has to face the task of designing the foundations meeting all safely and serviceability criteria but sometimes when there are numerous environmental and financial constrains, the use of some traditional methods become inevitable. This paper explains the application of timber piles to improve ground resistance to liquefaction and to secure the abutments of short to medium length bridges in an earthquake/liquefaction prone area in Bohol Island, Philippines. The limitations of using the common ground improvement methods (i.e., injection, dynamic compaction) because of either environmental or financial concerns along with the abundance of timber in the area made the engineers to use a network of timber piles behind the backwalls of the bridge abutments. The suggested timber pile network is simulated by numerical methods and its safety is examined. The results show that the compaction caused by driving of the piles and bearing capacity provided by timbers reduce the settlement and lateral movements due to service and earthquake induced loads.

  16. Analysis of Anti-Pulling Behaviors of Pile with Branch Plates%支盘桩抗拔承载特性分析

    Institute of Scientific and Technical Information of China (English)

    柯江

    2013-01-01

    支盘桩是一种新桩型,近年来在工程中得到比较广泛的应用,但对于支盘桩的研究多集中在受压承载特性,其抗拔承载特性的研究成果较少,在理论研究上还不够成熟,因此采用Abaqus软件,考虑了初始应力场,桩土之间的非线性接触以及土体材料的非线性,研究了支盘桩在上拔荷载作用下的承载特性,分析表明:在天然状态下土体对桩体的压力在支盘处最大,支盘桩达到抗拔极限承载力时,桩身轴力在支盘的上下出现突变,支盘下斜面以及桩底与土体产生了分离,塑性应变主要发生在支盘上的土体中;研究成果可为支盘桩的设计提供一定的理论依据.%The pile with branch plate is a new type of pile, widely used in engineering practice recently, but the study on the pile with branch plate focuses only on its compressive behaviors, there have been fewer studies on its an-ti-pulling behaviors, and the theory about this type of piles has not fully developed. Using software ABAQUS, the paper has studied the anti-pulling behaviors of pile with branch plates by considering the nonlinear contact between pile and soil, the initial stress field and the nonlinearity of soil material. The analysis shows that the soil pressure imposed on the pile was the largest at the branch plate under the natural condition, when the bearing capacity of pile with branch plates reached to the limit, the axial force of pile had mutations at the upper and lower of the branch plate, the lower slope of branch plate and soil produced a separation also between pile bottom and soil, the plastic strain occurred mainly in the upside of branch plate. The research results can provide some theoretical basis for the design of the pile with branch plate.

  17. Vertical Dynamic Impedance of Tapered Pile considering Compacting Effect

    Directory of Open Access Journals (Sweden)

    Wenbing Wu

    2013-01-01

    Full Text Available Based on complex stiffness transfer model, the vertical vibration of tapered pile embedded in layered soil is theoretically investigated by considering the compacting effect of the soil layer surrounding the tapered pile in the piling process. Allowing for the stratification of the surrounding soil and variable crosssection of the tapered pile, the pile-soil system is discretized into finite segments. By virtue of the complex stiffness transfer model to simulate the compacting effect, the complex stiffness of different soil segments surrounding the tapered pile is obtained. Then, substituting the complex stiffness into the vertical dynamic governing equation of tapered pile, the analytical solution of vertical dynamic impedance of tapered pile under vertical exciting force is derived by means of the Laplace technique and impedance function transfer method. Based on the presented solutions, the influence of compacting effect of surrounding soil on vertical dynamic impedance at the pile head is investigated within the low frequency range concerned in the design of dynamic foundation.

  18. Simulation of Pile-up in the ATLAS Experiment

    CERN Document Server

    Marshall, Z; The ATLAS collaboration

    2014-01-01

    The high luminosity of the LHC results in a significant background to interesting physics events known as pile-up. ATLAS has adopted two independent methods for modeling pile-up and its effect on analyses. The first is a bottom-up approach, using a detailed simulation of the detector to recreate each component of the pile-up background. The second uses specially recorded data events to emulate it. This article reports on the experience using both of these methods, including performance considerations, for simulating pile-up in ATLAS.

  19. Soil-cement piles by drilling-mixing method

    OpenAIRE

    ZOTSENKO N.; VYNNYKOV YU.; ZOTSENKO V.

    2015-01-01

    Development of the drilling-mixing technology lead to the appearance of the soil-cement piles. It has all advantages of the drilling piles, but it eliminate the problem of the well walls stability. Drilling-mixing technology consist in, that machine with drilling-mixing head loosen soil; impregnated it by laitance; and mixed. Piles are perform from the excavation bottom until design depth. The movable soil-cement mixture feels wells during all the process. Pile has cylindrical form with set s...

  20. 某高层建筑桩基事故分析与加固处理措施研究%Analysis on Accident and Corresponding Treatment Measures of Piles Instrumented in a Tall Building

    Institute of Scientific and Technical Information of China (English)

    吴明; 彭建兵; 王淑贤; 孟舒然; 臧明东

    2014-01-01

    通过低应变动测、钻探取芯、静载试验等检测手段分析了某高层建筑钻孔灌注桩存在的问题及桩基事故产生的原因。在对桩基事故详细分析的基础上,给出了桩基承载力不足和沉降过大桩基事故处理的补打钻孔灌注桩加基础厚底板方案。实践表明,该加固方案是可行的,不仅可满足桩基承载力的要求,且可减小群桩基础的差异沉降。%This paper analyzes an accident of bored piles instrumented in a tall building and proposes the cause of the accident using low strain dynamic testing, drilling core and static load test. Based on the detailed analysis of the accident of bored piles, reinforcement scheme composed of bored pile and thick beam-slab raft foundation can be used to treat the accident of large settlement and shortage of bearing capacity of bored piles. Engineering practice indicates that this reinforcement scheme is feasible, and can meet the requirement of pile bearing capacity, as well as decrease the differential settlement of pile groups.

  1. Longitudinal vibration of pile in layered soil based on Rayleigh-Love rod theory and fictitious soil-pile model

    Institute of Scientific and Technical Information of China (English)

    Lü Shu-hui; WANG Kui-hua; WU Wen-bing; C. J. LEO

    2015-01-01

    The dynamic response of pile in layered soil is theoretically investigated when considering the transverse inertia effect. Firstly, the fictitious soil-pile model is employed to simulate the dynamic interaction between the pile and the soil layers beneath pile toe. The dynamic interactions of adjacent soil layers along the vertical direction are simplified as distributed Voigt models. Meanwhile, the pile and fictitious soil-pile are assumed to be viscoelastic Rayleigh-Love rods, and both the radial and vertical displacement continuity conditions at the soil-pile interface are taken into consideration. On this basis, the analytical solution for dynamic response at the pile head is derived in the frequency domain and the corresponding quasi-analytical solution in the time domain is then obtained by means of the convolution theorem. Following this, the accuracy and parameter value of the hypothetical boundaries for soil-layer interfaces are discussed. Comparisons with published solution and measured data are carried out to verify the rationality of the present solution. Parametric analyses are further conducted by using the present solution to investigate the relationships between the transverse inertia effects and soil-pile parameters.

  2. Threat from Rubble-Pile Asteroids

    Science.gov (United States)

    Schultz, P. H.

    2015-12-01

    While chondrites are the most common meteoroids to enter our atmosphere, they represent a small fraction of recovered falls. Most stony meteorites disrupt during entry, consumed by ablation or lost by weathering; in contrast, small iron meteorites (entry at altitude; (c) no accessory meteorite falls; (d) "explosion" (not low-speed compression) crater; (e) infrasound/seismic data indicating a high-speed entry/collision; and (f) petrologic evidence for shock deformation/melting in breccias indicative of speeds >4 km/s. Although a monolithic chondrite (~ 10 m across) might allow surviving entry, most objects of this size contain multiple flaws, ensuring atmospheric disruption. Hence, an alternative "needle model" was proposed wherein a small rubble-pile object gradually re-shaped itself during entry [Schultz, 2008], a process that minimizes drag, thermal signatures of entry, and catastrophic disruption. First proposed to account for smaller than expected craters on Venus [Schultz, 1992], such a process resembles subsequent Shoemaker-Levy entry models [Boslough and Crawford, 1997] that predicted much deeper entry than standard models. Laboratory experiments at the NASA Ames Vertical Gun Range simulated this process by breaking-up hypervelocity projectiles into a cloud of debris and tracking its path at near-full atmospheric pressure. The resulting cloud of fragments exhibited less deceleration than a solid sphere at the same speed. Moreover, shadowgraphs revealed constituent fragments "surfing" the pressure jump within the mach cone/column. Previous models proposed that crater-forming impacts must be >50-100 m in diameter in order to survive entry [Bland and Artemieva, 2004]. The "needle model" for the Carancas meteorite entry, however, raises questions about this lower limit for threats by rubble-pile asteroids, e.g., Itokawa. Consequently, we modeled the fate of a rubble-pile entering earth's atmosphere using GEODYN, an Eulerian code with adaptive mesh refinement

  3. 某采煤沉陷区综合治理工程基桩试验研究%Research on comprehensive treatment of foundation pile experiments in some mining subsidence areas

    Institute of Scientific and Technical Information of China (English)

    赵惠华; 李建军

    2011-01-01

    According to the design for the rock-socketed part's bearing piles with manual digging hole reinforced concrete in the comprehensive treatment of the residential buildings in some mining subsidence areas,the paper adopts the rock foundation loading experiment to identify the standard value of the saturated single pile strength in bearing course at pile ends and uses the dynamic detection method to test the quality of the engineering piles,and proves the effect of using rock-socketed part's bearing piles with manual digging hole reinforced concrete in treating the mining subsidence areas is better.%通过某采煤沉陷区综合治理工程住宅楼人工挖孔钢筋混凝土嵌岩端承桩设计,采用岩基载荷试验方法确定了桩端持力层岩石饱和单桩抗压强度标准值和采用动力检测法检测了工程桩的桩身质量,结果表明人工挖孔钢筋混凝土嵌岩端承桩在处理某采煤沉陷区效果较好。

  4. Numerical Simulation for the Soil-Pile-Structure Interaction under Seismic Loading

    OpenAIRE

    Lifeng Luan; Yunbin Liu; Ying Li

    2015-01-01

    Piles are widely used as reinforcement structures in geotechnical engineering designs. If the settlement of the soil is greater than the pile, the pile is pulled down by the soil, and negative friction force is produced. Previous studies have mainly focused on the interaction of pile-soil under static condition. However, many pile projects are located in earthquake-prone areas, which indicate the importance of determining the response of the pile-soil structure under seismic load. In this pap...

  5. Investigation of Pile- Soil Interaction Subjected to Lateral Loads in Layered Soils

    OpenAIRE

    A. Avaei; Ghotbi, Abdoul R.; M. Aryafar

    2008-01-01

    To stabilize infrastructures such as tall buildings, bridges, etc., piles are used to resist lateral loads created from earth pressure, wind, waves and earthquake extensively. Pile design requires understanding of how the load is transferred from a pile to surrounding soil and vice versa. Pile properties, soil stress-strain behavior and pile-soil interaction play important roles in pile-response subjected to lateral loads. A study was carried out to investigate the effects of above-mentioned ...

  6. Application of Pile-soil Interaction in Dealing with the Quality Problem of Pile Foundation%桩土共同作用在处理桩基质量问题中的应用

    Institute of Scientific and Technical Information of China (English)

    曾志辉; 张和平

    2012-01-01

    This paper introduces a method of how to transform the problem pile into usable pile,and bear upper load with the basement bottom slab together. Practical applications show that this method offers so many good features:safe, reliable ,convenient construction and low cost.%某办公楼桩基础混凝土由于施工原因形成废桩,介绍如何利用桩土共同作用,利用原有废桩,并与原有地下室底板共同作用承担上部荷载。实践表明该方法具有安全可靠、施工方便、经济性好等特点。

  7. INTERACTION OF A LONG SINGLE PILE THAT HAS A DOUBLE-LAYER BASE WITH ACCOUNT FOR COMPRESSIBILITY OF THE PILE SHAFT

    OpenAIRE

    Ter-Martirosyan Zaven Grigor'evich; Trinh Tuan Viet

    2012-01-01

    WITH ACCOUNT FOR COMPRESSIBILITY OF THE PILE SHAFT The authors provide their solution to the problem of interaction of a long compressible pile that has a double-layer linear deformable base. The paper demonstrates that taking account of compressible properties of the pile material leads to qualitatively new distribution of shearing stresses over the surface of a cylindrical pile. It is noteworthy that increase of the pile length and stiffness of the upper section of the base raise the sha...

  8. Analysis on pile-soil interaction of pile-supported composite foundation%桩承式加网复合地基桩土共同作用分析

    Institute of Scientific and Technical Information of China (English)

    王瑞芳; 王克宇

    2015-01-01

    By the method of shearing displacement analysis, the interactions between single pile with cap and soil are ana-lyzed, the formula of displacement and axial force for pile with cap under uniform loading are obtained. The finite element soft-ware, ABAQUS, is used to analyze the bearing performance of single pile in three dimensions, and the results are compared with those of the analytical calculation method. The comparison shows that the settlements of roadbed surface and pile top as well as the pile axial forces calculated by the above two methods are similar. The analytical calculation result is in consonance with the measured data, which verifies the accuracy of analytical calculation method.%采用剪切位移法分析了桩承式带桩帽单桩与桩间土的相互作用,得出均布荷载下带桩帽单桩的桩身位移、轴力公式. 用ABAQUS有限元软件对带帽单桩进行三维数值分析,将数值计算结果与解析公式结果进行比较,计算表明解析公式计算出的桩身轴力、桩顶沉降、路基表面沉降和有限元计算值接近. 将现场实测数据与解析计算结果进行比较,解析计算的沉降结果和实测沉降数据较吻合,说明所提出的解析法计算公式准确性较好,对工程应用有一定的参考价值.

  9. Examination of graphite pile radiation conditions of industrial reactors

    International Nuclear Information System (INIS)

    Radiation states of graphite piles of three industrial uranium-graphite reactors are investigated. The level, composition, distribution of the pile radioactive contamination, parameters of neutron and gamma radiations are determined. The forecast of variation of radionuclide activity in graphite in dependence on the cooling time is developed

  10. Cause Analysis of Wuhan Tianheng Building Pile Accident

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The geological condition and the original structure feature and foundation design of Wuhan Tianheng building are described. The accident appearance of pile foundation in the construction execution of work is illustrated. The generating source of this pile foundation accident is analyzed in great details.``

  11. Modeling the damming effect of pile foundations (Tomsk city)

    Science.gov (United States)

    Kuzevanov, K. I.; Pokrovsky, D. S.; Pokrovsky, V. D.; Kuzevanov, K. K.

    2016-03-01

    The authors have considered the impact of pile foundations on the structure of filtration flows in the conditions of urban development. Hydrodynamic simulation methods have shown that a groundwater level rise might occur due to the damming effect that can be created by pile fields in semipermeable rocks. This phenomenon can intensify anthropogenic waterlogging processes in urbanized territories.

  12. Physical Modelling of Cyclic Laterally Loaded Pile in Cohesionless Soil

    DEFF Research Database (Denmark)

    Hansen, Mette; Wolf, Torben K.; Rasmussen, Kristian L.;

    Offshore wind turbines are normally founded with large diameter monopiles and placed in rough environments subjected to variable lateral loads from wind and waves. A long-term lateral loading may create rotation (tilt) of the pile by change in the pile-soil system which is critical in the service...

  13. Assessment of timber piles in Clallam County, Washington

    Science.gov (United States)

    Pandey, Arun K.; Tyler, Ross; Arnette, Clyde G.; Anthony, Ronald W.

    1998-03-01

    Timber bridges are very common in state and rural highway systems. According to the National Bridge Inventory (NBI), there are 41,743 timber bridges in the United States and another 42,102 bridges with timber decks as a part of the superstructure. As these bridges age, there is a critical need for reliable inspection and assessment methods for evaluating timber members. Under an FHWA mandate, these bridges also need to be evaluated for scour susceptibility. Knowledge of the length of timber piles supporting the bridge is a vital component in calculating scour resistance of a bridge. However, records of timber pile lengths are often nonexistent or incomplete due to the construction practices for timber piles. This paper presents nondestructive evaluation (NDE) techniques used for assessing timber piles on 10 bridges in Clallam County, Washington. Stress wave velocity and resistance drilling techniques were used to determine the presence of and quantify the extent of decay in the piles. A longitudinal stress wave technique was used for determining the length of timber piles. Determination of piles with decay aided in establishing maintenance and repair needs on the bridge substructures. Pile length estimates enabled Clallam County Road Department to determine the scour-susceptibility of these bridges.

  14. Visualization of soil arching in flexible piled embankments

    Indian Academy of Sciences (India)

    Tuğba Eskışar

    2015-10-01

    Piled embankments rely on soil arching, but, when geogrid reinforcements are used, membrane action within the reinforcement contributes to load distribution. The arching of soil in unreinforced and reinforced piled embankments is evaluated in this study. A small-scale test apparatus is used to model the settlement up to 5 mm in an embankment with four pile elements. Visual inspection of the soil settlement and soil-reinforcement interaction is important to explain the mechanism of arching. In this study, X-ray Computed Tomography (CT) method was used as a non-destructive technique. The arching of soil between the piles was observed in the case of rigid piles and in the case of flexible piles with grid type of reinforcement. The load carrying capacity increased up to 33% in the case of geogrid reinforcement, and the differential settlement decreased around 35%, proving the efficiency of piled embankments with geogrid reinforcements. It is also shown that, using X-ray CT method and visualization techniques provides a better understanding of soil behavior in a reinforced embankment with the flexible pile foundation system.

  15. The homogenisation of bulk material in blending piles.

    NARCIS (Netherlands)

    Gerstel, A.W.

    1979-01-01

    In this thesis the homogenisation of bulk material in three types of piles is dealt with. The homogenisation implies that the fluctuations of a material proprety in the input flow of the pile are transformed into output fluctuations, whereby the latter ones are evened out. Analyses are presented con

  16. Perturbation analysis on post-buckling behavior of pile

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The nonlinear large deflection differential equation, based on the assumption that the subsoil coefficient is the 2nd root of the depth, was established by energy method. The perturbation parameter was introduced to transform the equation to a series of linear differential equations to be solved, and the deflection function according with the boundary condition was considered. Then,the nonlinear higher-order asymptotic solution of post-buckling behavior of a pile was obtained by parameter-substituting. The influencing factors such as bury-depth ratio and stiffness ratio of soil to pile, slenderness ratio on the post-buckling behavior of a pile were analyzed. The results show that the pile is more unstable when the bury-depth ratio and stiffness ratio of soil to pile increase,and although the buckling load increases with the stiffness of soil, the pile may ruin for its brittleness. Thus, in the region where buckling behavior of pile must be taken into account, the high grade concrete is supposed to be applied, and the dynamic buckling behavior of pile needs to be further studied.

  17. Three kinds of soft soil pile in a coastal area into a contrast test pile method%沿海某地区软土地基中三种基桩成桩方式的试验对比

    Institute of Scientific and Technical Information of China (English)

    李永栋; 贾向新

    2015-01-01

    通过某大型工业建设项目的试桩工作,针对 PHC预应力管桩、长螺旋后插钢筋笼灌注桩、后压浆长螺旋后插钢筋笼灌注桩分别进行了静载荷试验。根据试验结果及调查,认为针对该地区的地层,该三种施工工艺都是适合的。通过单桩承载力分析,得出后压浆可以提高灌注桩承载力30%以上。在该地区施工长螺旋后插钢筋笼灌注桩时,后插钢筋笼的质量对成桩影响很大,在施工时应引起注意。%the static load test of a large scale industrial construction proj ect is carried out,aiming at the PHC prestressed pipe pile,the long screw and the post grouting pile,and the post grouting long screw.According to the results of the experiment and investigation,it is believed that the three kinds of construction technology are suitable for the area.Through the analysis of the bearing ca-pacity of single pile,the post grouting can improve the bearing capacity of cast-in-place pile 30%or more.In this area,the quality of the post bar cage has a great influence on the construction of the reinforced bar cage.

  18. 论钢绳冲孔桩质量控制%On the Quality Control of Steel Sling Punching Pile

    Institute of Scientific and Technical Information of China (English)

    黄云柱

    2013-01-01

      施工项目中,冲孔桩法是一种新型地基处理技术。该技术对加固处理不良地基、改善原天然土层的工程特性及提高地基承载力有着显著的作用。文章介绍了冲孔桩的技术特点、作用机理、施工要点及质量控制措施。%Punching pile method is a new type of foundation treatment technology in construction project, which play an im-portant role in reinforcing and handling the bad foundation, improving the engineering properties of natural soil, enhancing bearing capacity of foundation. The paper introduces the technical features, mechanism of action, key points of construction, the measures of quality control of punching pile.

  19. Application of CFG Pile in Foundation Treatment%CFG桩在地基处理中的应用

    Institute of Scientific and Technical Information of China (English)

    高小强

    2014-01-01

    CFG (Cement Fly-ash Gravel) is composed of gr-avel, stone dust, sand, fly ash mixing cement with water. The application of CFG pile can effectively increase foundation bearing capacity and reduce the set lement, so as to ensure the economic construction. This article carried on the analysis to the application of CFG pile in foundation treatment.%CFG(Cement Fly-ash Gravel)由碎石、石屑、砂、粉煤灰掺水泥加水拌和而成。采用CFG桩能够有效地增加地基的承载力、降低沉降量,从而保证施工的经济性。文章对CFG桩在地基处理中的应用进行了分析。

  20. 预应力混凝土空心方桩桩体抗弯试验研究%A Study on the Transverse Test of Hollow and Square Prestressed Concrete Pile

    Institute of Scientific and Technical Information of China (English)

    龙绛珠; 王凤

    2012-01-01

    The relationships between stress and strain and flexural bearing capacity and failure property of hol- low and square prestressed concrete pile were analyzed through pile bending experiment in which pile edge length is 300ram (400ram}, inner diameter of 150ram {240ram}, pile length of 10 m. The experiment results show that the flexural bearing capacity of hollow and square prestressed concrete pile is higher than that of the standard value of regulations. The flexural beating capacity is ascertained through correction factor of tlexural strength. The fissures of pile spread in the range of 7m in the mid span. The piles have higher flexural bearing capacity after bending failure.%通过对边长300ram、内径150ram和边长400ram内径、240ram的两组预应力混凝土空心方桩桩体抗弯试验,分析研究预应力混凝土空心方桩在受弯承载力作用下桩体的应力应变情况、抗弯承载力及破坏特性。抗弯试验结果表明:预应力混凝土空心方桩抗弯承载能力明显优于规范标准值,引用抗弯强度修正系数来校核,在弯矩作用下桩体裂缝分布于跨中7m范围内(试验选用的桩长皆为lore),桩体受弯破坏后仍具有较高的抗弯承载力。

  1. Creep and long-term bearing capacity of long piles submerged into the clay soil massif ПОЛЗУЧЕСТЬ И ДЛИТЕЛЬНАЯ НЕСУЩАЯ СПОСОБНОСТЬ ДЛИННОЙ СВАИ, ПОГРУЖЕННОЙ В МАССИВ ИЗ ГЛИНИСТОГО ГРУНТА

    Directory of Open Access Journals (Sweden)

    Ter-Martirosyan Zaven Grigor’evich

    2013-01-01

    Full Text Available Interaction between long piles and the adjacent soil has a spatial and temporal nature. This phenomenon is based on a set of non-linear and rheological properties of soils. Distribution of lateral forces between the surface and the pile toe is heavily dependent on the above properties. The process of formation of the stress-strain state around the pile can demonstrate decaying, constant or progressive velocity depending on the rheological processes in the soil that may be accompanied by hardening and softening processes at one and the same time. These processes may be caused by destruction and restoration of ties between clay soil particles, soil compaction and de-compaction. Predominance of the process of hardening leads to damping, while predominance of the process of softening causes progressive destruction. Description of this multi-component process depends on the rheological model of the soil. This research is based on the modified rheological model originally designed by Maxwell. The authors consider solutions to the problem of quantification of the stressstrain state of soil around the pile and their interaction. This research makes it possible to project motion patterns of long piles over the time and evaluate the limit of their long-term bearing capacity.Изложена постановка и решение задачи о взаимодействии длинной сваи с окружающим грунтом, обладающим ярко выраженными реологическими свойствами, в т.ч. вязкостью, упрочнением, разупрочнением, описываемыми модифицированной моделью Максвелла. Показывается, что в этом случае осадка сваи при действии постоянной нагрузки может развиваться с затухающей, постоянной и знако

  2. H型长钢桩尖在密实土层中的应用%Application of long H?type steel pile tip in compact soil layer

    Institute of Scientific and Technical Information of China (English)

    孟晓宁; 于云山

    2016-01-01

    在钢筋混凝土桩基施工时,如果遇到工程区域地质持力层较密实且埋藏较浅或者持力层上面有较密实的覆盖层的情况,往往会造成沉桩困难、桩的入土深度不能满足使用要求等问题.结合具体工程的实践经验对此类工程问题进行分析,提出钢筋混凝土桩组合H型长钢桩尖的解决方案,并与普通钢筋混凝土桩基方案进行对比、通过计算及试桩试验对方案进行验证、对方案优点及适用性进行总结.%During the reinforced concrete pile foundation construction process, when the bearing stratum of engineering region is more compact and shallow buried or be covered by dense layer, the problems are tend to hap?pen, such as pile?sinking difficultly or embedded depth of pile cannot meet operating requirement. Combined with specific engineering practice experience and the analysis of such problems, the solution of reinforced concrete pile with long H?type steel pile tip was mentioned in this paper. The advantage and applicability of this solution was summarized by contrast with common reinforced concrete pile foundation, and it was verified by calculation and test piles.

  3. Variable rigidity design method for balance settlement of generalized composite pile foundation%广义复合桩基的变刚度调平设计

    Institute of Scientific and Technical Information of China (English)

    李学明; 周峰; 蒋超

    2013-01-01

    Differential settlement was reason which caused internal force of foundation and substress in superstructure increase, raft incrassate and steel augment. Numeric analysis against variable rigidity design of friction and end-bearing composite pile foundation was advanced. Bearing rigidity of friction composite pile foundation could be distributed rationally through different setting of length of piles,diameter of piles and distance of piles. It can reduce differential settlement. Settlement adjuster resolves problem that carrying capacity of subgrade can not be utilized. It reduces the differential settlement of foundation through optimizing and regulating the bearing rigidity of settlement adjuster.%差异沉降是导致基础内力和上部结构次应力增大、板厚与配筋增加的根源所在.本文分别对摩擦桩复合桩基和端承桩复合桩基的变刚度调平进行了数值分析.结果显示:摩擦桩复合桩基可以通过不同桩长、桩径、桩距的设置方式来对桩基的支承刚度进行合理的分布,以达到减小差异沉降的目的.端承桩复合桩基通过设置变形调节器,不仅解决了端承桩基无法利用地基土承载力的难题,而且可对调节器支承刚度的进一步优化和调整,还能显著减小基础的不均匀沉降.

  4. Optimum design methodologies for pile foundations in London

    Directory of Open Access Journals (Sweden)

    Christos Letsios

    2014-12-01

    Full Text Available Given the importance of pile foundations in geotechnical engineering for supporting high-significance structures such as bridges, high-rise buildings, power plant stations, offshore platforms and museums, it becomes a necessity to find the best pile foundation design in terms of performance and economy. The number of piles required might exceed several hundreds or even thousands while the pile foundation cost might exceed 20% of the construction cost of the superstructure. In this work the problem of finding optimized designs of pile foundations is examined and is performed in accordance to two design code recommendations, namely Eurocode 7 and DIN 4014. The proposed structural optimization procedure is implemented in two real-world cases both located in London, UK in order to assess the efficiency of the proposed design formulation.

  5. The Analysis of Soil Resistance During Screw Displacement Pile Installation

    Science.gov (United States)

    Krasinski, Adam

    2015-02-01

    The application of screw displacement piles (SDP) is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque) during screw auger penetration in non-cohesive subsoil based on CPT is proposed.

  6. Dynamic Soil-Pile Interaction for large diameter monopile foundations

    DEFF Research Database (Denmark)

    Zania, Varvara

    2013-01-01

    of the study is to analyse the dynamic interaction of the soil and a single pile embedded in it by accounting for the geometric and stiffness properties of the pile. In doing so, a semi – analytical approach is adopted based on the fundamental solution of horizontal pile vibration by Novak and Nogami...... eigenfrequencies of the soil layer do not affect the soil – pile interaction. The decrease of the eigefrequency of the OWT depends on the aforementioned variation of the dynamic stiffness and the slenderness ratio of the monopile....... left between two restrictive frequency areas. Moreover the design of monopile foundations when subjected to combined lateral and moment loading (the latter arising from the eccentricity of the applied wind pressure) usually dictates a large diameter steel pile with small slenderness ratio. Hence, aim...

  7. Static Tension Tests on Axially Loaded Pile Segments in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    showed best agreement with the traditional design method given in the American Petroleum Institute (API) design code. When t-z curves obtained from the test results were compared to t-z curve formulations found in the literature, the Zhang formulation gave good predictions of the initial and post......This paper provides laboratory test results of static axially loaded piles in sand. With a newly developed test setup, the pile-soil interface friction was investigated by using an open-ended steel pile segment with a diameter of 0.5 m. Use of a pile length of 1 m enabled the pile-soil interface...... friction to be analyzed at a given soil horizon while increasing the vertical effective stress in the sand. Test results obtained by this approach can be analyzed as single t-z curves and compared to predictions of unit shaft friction from current design methods for offshore foundations. The test results...

  8. The Analysis of Soil Resistance During Screw Displacement Pile Installation

    Directory of Open Access Journals (Sweden)

    Krasinski Adam

    2015-02-01

    Full Text Available The application of screw displacement piles (SDP is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque during screw auger penetration in non-cohesive subsoil based on CPT is proposed.

  9. Distributed fibre optic strain measurements on a driven pile

    Science.gov (United States)

    Woschitz, Helmut; Monsberger, Christoph; Hayden, Martin

    2016-05-01

    In civil engineering pile systems are used in unstable areas as a foundation of buildings or other structures. Among other parameters, the load capacity of the piles depends on their length. A better understanding of the mechanism of load-transfer to the soil would allow selective optimisation of the system. Thereby, the strain variations along the loaded pile are of major interest. In this paper, we report about a field trial using an optical backscatter reflectometer for distributed fibre-optic strain measurements along a driven pile. The most significant results gathered in a field trial with artificial pile loadings are presented. Calibration results show the performance of the fibre-optic system with variations in the strain-optic coefficient.

  10. Centrifuge Modeling of Piles Subjected to Lateral Loads

    Science.gov (United States)

    Brant, Logan; Ling, Hoe I.

    There are many applications where piles are employed to absorb and deflect lateral impact loads. Structural elements of this type are used to protect infrastructure and are commonly found at marine sites. A series of model tests have been conducted using Columbia University's centrifuge facility to better understand the performance of piles subjected to these loading conditions. A device was designed to install and laterally load single model piles during centrifuge flight. This device uniquely contains two lateral loading systems, one which allows static testing and another appropriate for dynamic tests. This research examines the behavior of tubular steel piles embedded within dry or saturated soil and subjected to varied rates of lateral loading. This investigation provides insight on the contribution of lateral loading rates to the behavior of piles.

  11. Pre-Stressed Rope Reinforced Anti-Sliding Pile

    Institute of Scientific and Technical Information of China (English)

    XU Jun; WANG Chenghua

    2006-01-01

    Pre-stressed rope reinforced anti-sliding pile is a composite anti-sliding structure. It is made up of pre-stressed rope and general anti-sliding pile. It can bring traditional anti-sliding pile's retaining performance into full play, and to treat with landslide fast and economically. The difference between them is that the pre-stressed rope will transfix the whole anti-sliding pile through a prearranged pipe in this structure. The working mechanics, the design method and economic benefit are studied. The results show that the pre-stressed rope reinforced anti-sliding pile can treat with the small and middle landslides or high slopes well and possess the notable advantage of technology and economic.

  12. POST PRESSURE GROUTING PILE OF BOREHOLE USED IN A CONSTRUCTION SITE IN WEINAN%钻孔灌注桩后压浆法在渭南某工地应用

    Institute of Scientific and Technical Information of China (English)

    赵跃文; 王佳武; 李敏杰; 王锋涛; 张少林; 张波

    2012-01-01

    With the development of construction of high buildings in resent years, higher standards for foundation bearing capacity are required. Bored piles for foundation of high buildings are com- mon in China. In order to meet the requirements of construction design, bearing stratum of bored piles is required to be comparatively intact rocks or cobble layers with high bearing capacity. Piles with great length and big size increase the cost ratio of whole subgrade construction and difficulties in construction. At a construction site in Weinan city, bored piles with a diameter of 600 mm and a length of 30m were used in subgrade construction, which couldn't reach the requirements of load- bearing capacity above. Post pressure grouting of berehole is adopted for increasing side friction of piles and bearing capacity at pile ends, which could enhance the load-bearing capacity of subgrade piles and reduced the possibility of subsidence of subgrade piles.%近年来我国的高层建筑迅猛发展,对地基承载力的要求越来越高,高层建筑的基础形式一般采用灌注桩基础。为了满足设计要求;灌注桩的持力层要求是较为完整的岩石层或承载力较高的卵石层,桩长和桩径尺寸往往很大,使得地下部分的造价在整个工程总造价中占较大的比例;同时;由于桩长很长,也给施工造成很大的困难。渭南市某工地采用φ300mm桩径,桩长30m,试桩施工完成后,经过桩基检测,桩的承载力不能满足上部荷载的要求,其后采用后压浆法来提高桩的侧摩阻力和桩端承载力,从而使灌注桩达到提高基桩承载力、减少基桩沉降的结果。

  13. Influence of space of double row piles on soil arching effect

    Directory of Open Access Journals (Sweden)

    Zhao bo

    2015-02-01

    Full Text Available FLAC3d software, based on continuous theory, is used to analysis influence of space of double row piles on soil arching effect. The result shows that different from single row pile, double row piles will produce soil arching effect at front pile and rear pile severally, this phenomenon is called multiple soil arching effect; the residual load of front of front row pile will increase,the soil arch zone and the soil arching effect will decrease with the continuous increase of double row pile spacing.At the same time the soil arching effect of rear pile decreases, while the soil arching effect of front pile increases and finally the soil arching effect between front pile and rear pile will be equal.

  14. Passive magnetic bearing configurations

    Science.gov (United States)

    Post, Richard F.

    2011-01-25

    A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

  15. Maintenance Free Bearings

    OpenAIRE

    S. M. Muzakkir & Harish Hirani

    2015-01-01

    In the present research work the need of a Maintenance Free Bearings (MFB) is established. The paper presents preliminary friction calculations to highlight the ways to achieve maintenance free bearings. The existing technologies of well established maintenance free bearings are described. The hybridization of bearing technologies to achieve low cost maintenance free bearings has been exemplified. Finally a combination of passive magnetic repulsion and hydrodynamics ha...

  16. Remedial action for radioactive waste rock piles in China

    International Nuclear Information System (INIS)

    The Chinese government has conducted remedial action for radioactive waste rock piles since 1990. The radioactive waste rocks produced in the course of geological exploration of uranium deposits are widely distributed over several hundreds of locations in more than 20 provinces in China. The following remedial actions for radioactive waste rock piles have been undertaken in China: 1. Protecting dams for stabilizing the piles have been built. A total length of about 50,000 m of these dams has been completed. 2. Soil layers have been emplaced on the radioactive waste rock piles. The focus of the action is to eliminate the radiation harmful to public health. A total area of 750,000 square meters of soil has been placed on the piles in China. 3. Radioactive waste rock piles have been vegetated. Aesthetic shaping of the landscape in the exploratory district of the uranium deposits is our expectant goal. A total area of about 560,000 square meters of vegetation has been placed on the soil covering the piles. Through these remedial actions, the environmental situation has been extensively improved in the remedial districts. The individual annual effective dose equivalent is less than 1 Sv/a. The radon emission rate is less than 20 pCi/m2.s. The gamma ray external exposure rate has been greatly reduced. Copyright (2001) Material Research Society

  17. Analysis of Wave Fields induced by Offshore Pile Driving

    Science.gov (United States)

    Ruhnau, M.; Heitmann, K.; Lippert, T.; Lippert, S.; von Estorff, O.

    2015-12-01

    Impact pile driving is the common technique to install foundations for offshore wind turbines. With each hammer strike the steel pile - often exceeding 6 m in diameter and 80 m in length - radiates energy into the surrounding water and soil, until reaching its targeted penetration depth. Several European authorities introduced limitations regarding hydroacoustic emissions during the construction process to protect marine wildlife. Satisfying these regulations made the development and application of sound mitigation systems (e.g. bubble curtains or insulation screens) inevitable, which are commonly installed within the water column surrounding the pile or even the complete construction site. Last years' advances have led to a point, where the seismic energy tunneling the sound mitigation systems through the soil and radiating back towards the water column gains importance, as it confines the maximum achievable sound mitigation. From an engineering point of view, the challenge of deciding on an effective noise mitigation layout arises, which especially requires a good understanding of the soil-dependent wave field. From a geophysical point of view, the pile acts like a very unique line source, generating a characteristic wave field dominated by inclined wave fronts, diving as well as head waves. Monitoring the seismic arrivals while the pile penetration steadily increases enables to perform quasi-vertical seismic profiling. This work is based on datasets that have been collected within the frame of three comprehensive offshore measurement campaigns during pile driving and demonstrates the potential of seismic arrivals induced by pile driving for further soil characterization.

  18. Three-dimensional analysis of slopes reinforced with piles

    Institute of Scientific and Technical Information of China (English)

    高玉峰; 叶茂; 张飞

    2015-01-01

    Based on the upper bound of limit analysis, the plane-strain analysis of the slopes reinforced with a row of piles to the 3D case was extended. A 3D rotational failure mechanism was adopted to yield the upper bound of the factor of safety. Parametric studies were carried out to explore the end effects of the slope failures and the effects of the pile location and diameter on the safety of the reinforced slopes. The results demonstrate that the end effects nearly have no effects on the most suitable location of the installed piles but have significant influence on the safety of the slopes. For a slope constrained to a narrow width, the slope becomes more stable owing to the contribution of the end effects. When the slope is reinforced with a row of piles in small space between piles, the effects of group piles are significant for evaluating the safety of slopes. The presented method is more appropriate for assessing the stability of slopes reinforced with piles and can be also utilized in the design of plies stabilizing the unstable slopes.

  19. Réparation des pieux battus dans les sables carbonatés Repair of Driven Piles in Calcareous Formations

    Directory of Open Access Journals (Sweden)

    Nauroy J. F.

    2006-11-01

    Full Text Available Les formations carbonatées rencontrées en de nombreuses zones d'activités pétrolières en mer posent de difficiles problèmes de dimensionnement et de mise en place des pieux. Sur plusieurs sites de sable carbonaté, la capacité portante des pieux battus se révèle beaucoup plus faible que prévu et des techniques de réparation doivent être étudiées. Dans ce contexte, l'ARGEMA (Association de Recherche en Géotechnique Marine, groupement français d'organismes de recherche, de compagnies pétrolières et de contracteurs offshore, a expérimenté une réparation d'un pieu expérimental de 30 cm de diamètre et 23 m de long battu dans un sable carbonaté. Le frottement latéral de ce pieu mobilisé juste après battage était très faible. La réparation a consisté à injecter du coulis de ciment à partir d'un forage situé à 40 cm du pieu. Cet article décrit les procédures et les caractéristiques des injections réalisées et leurs conséquences sur la capacité portante du pieu. Le frottement entre le pieu et le terrain s'accroît avec le volume de ciment injecté; les valeurs maximales obtenues sont du même ordre de grandeur que celles observées avec un pieu foré-cimenté. The calcareous formations encountered in many zones of offshore petroleum activity raise difficult problems for designing and installing foundation piles. On several sites with calcareous sands, the bearing capacity of driven piles proves to be much less than had been planned, and repair techniques have to be examined. Within this context, ARGEMA (Association de Recherche en Géotechnique Marine, a french group of research organizations, oil companies and offshore contractors, has tested a repair of an experimental pile 30 cm in diameter and 23 m long driven into a calcareous sand. The skin friction of this pile, mobilized just after driving, was found to be very low. The repair-job consisted in injecting grout from a drilled borehole located at some tens

  20. Experimental Study on Uplift Bearing Capacity of Micropiles for Transmission Tower%微型桩杆塔基础上拔试验研究

    Institute of Scientific and Technical Information of China (English)

    苏荣臻; 陈培; 鲁先龙

    2011-01-01

    Field tests were done to study the uplift bearing mechanism and the uplift design method of micropiles. Study shows that the uplift bearing capacity of single pile is composed of pile weight and lateral friction; the second grouting can increase the uplift bearing capacity of micropiles, calculating the uplift bearing capacity of two-grouting micropiles must consider the effect of the second grouting; the obliquity of inclined piles in the micropile group can be 10°; under uplift load, the bearing load of the angle pile is maximum, the side pile is the second, and the middle pile is minimum; in this experimental condition, the uplift pile group effect coefficient is 0. 7.%通过现场真型试验,对微型桩基础抗拔承载机理及其抗拔承载力计算方法进行了研究.试验研究表明:微型桩单桩抗拔承载力可由桩身自重和桩周侧摩阻力相加组成;二次注浆有利于提升微型桩抗拔承载力,在进行微型桩抗拔承载力计算时应考虑二次注浆的提升作用;群桩基础中布置斜桩可采用10度倾角;由于承台对上拔荷载的重分配,在上拔荷载作用下,角桩承力最大,边桩次之,中桩最小;本次试验条件下,微型桩抗拔群桩效应系数可取0.7进行计算.

  1. Ice bustles on quay piles : field studies and numerical simulations

    Energy Technology Data Exchange (ETDEWEB)

    Loset, S.; Marchenko, A. [Norwegian Univ. of Science and Technology, Trondheim (Norway)]|[Svalbard Univ. Centre, Spitsbergen (Norway)

    2008-07-01

    The additional gravity action created by the accumulation of ice on coastal structures and piles in cold climates may create a potential threat for the safety of the structures, particularly for mooring and fendering of floating structures and jacket-type structures. The gravity action is particularly critical in areas with changes in water level, such as large tide amplitudes. Ice bustle on piles may also increase the water line, thereby creating more horizontal action from moving ice fields. This study examined the growth and properties of ice bustles on quay piles in the Svea coal harbour, Spitsbergen during the winter and spring of 2007. Their formation was found to be related to super-cooling of piles relative to the temperature of surrounding water, when the heat conductivity of the pile material is higher than the heat conductivity of the water. Ice grows laterally from the surface of the pile at larger depths than the thickness of the surrounding level ice. The bustles are kept in place during water level changes because of the high adhesion between the ice and pile. The vertical and horizontal size of ice bustles formed on cylindrical quay steel piles in the study area was about 1.5 m with slightly downward sloping side walls. At high tide, the top surface coincided with the water level while at low tide, it was almost above the water surface. The Comsol Multiphysics 3.3a mathematical model was used to describe the formation of ice bustle around the cylindrical pile. Ice bustle growth was simulated with a constant water level while taking into consideration changes in tide and water level. This paper also described how the size of ice bustle is influenced by meteorological conditions, time and tidal amplitude. 1 refs., 1 tab., 10 figs.

  2. Analysis of static and dynamic pile-soil-jacket behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Azadi, Mohammad Reza Emami

    1998-12-31

    In the offshore industry, recent extreme storms, severe earthquakes and subsidence of the foundation of jacket platforms have shown that new models and methods must take into account the jacket- pile-soil foundation interaction as well as the non-linear dynamic performance/loading effects. This thesis begins with a review of the state of art pile-soil interaction model, recognizing that most existing pile-soil models have been established based on large diameter pile tests on specific sites. The need for site independent and mechanistic pile-soil interaction models led to the development of new (t-z) and (p-y) disk models. These are validated using the available database from recent large diameter pile tests in the North Sea and Gulf of Mexico. The established static disk models are applied for non-linear static analysis of the jacket-pile-soil system under extreme wave loading. Dynamic pile-soil interaction is studied and a new disk-cone model is developed for the non-linear and non-homogeneous soils. This model is applied to both surface and embedded disks in a soil layer with non-linear properties. Simplified non-linear as well as more complex analysis methods are used to study the dynamic response of the jacket platform under extreme sea and seismic loading. Ductility spectra analysis is introduced and used to study the dynamic performance of the jacket systems near collapse. Case studies are used to illustrate the effects of structural, foundation failure characteristics as well as dynamic loading effects on the overall performance of the jacket-pile-soil systems near ultimate collapse. 175 refs., 429 figs., 70 tabs.

  3. Pile mixing increases greenhouse gas emissions during composting of dairy manure

    Science.gov (United States)

    The effect of pile mixing on greenhouse gas (GHG) emissions from stored dairy manure was determined using large flux chambers designed to completely cover pilot-scale manure piles. GHG emissions from piles that were mixed four times during the 80 day trial were about 20% higher than unmixed piles. ...

  4. 40 CFR 761.347 - First level sampling-waste from existing piles.

    Science.gov (United States)

    2010-07-01

    ... existing piles. 761.347 Section 761.347 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... from existing piles. (a) General. Sample piles that are either specifically configured for sampling... alternate sampling plan in accordance with § 761.62(c). (b) Specifically configured piles. A...

  5. Laboratory Testing of Cyclic Laterally Loaded Pile in Cohesionless Soil

    DEFF Research Database (Denmark)

    Roesen, Hanne Ravn; Ibsen, Lars Bo; Hansen, Mette;

    2013-01-01

    in the serviceability limit state. In this paper small-scale testing of a pile subjected to cyclic, lateral loading is treated in order to investigate the effect of cyclic loading. The test setup, which is an improvement of a previous setup, is described and the first results of testing are compared with previous......Offshore wind turbines are normally founded with large diameter monopiles and placed in rough environments subjected to variable lateral loads from wind and waves. A long-term lateral loading may create rotation (tilt) of the pile by change in the pile-soil system which is critical...

  6. Assessing the impact of pile driving upon fish

    OpenAIRE

    Hawkins, Anthony

    2005-01-01

    Pile driving associated with the removal and reconstruction of a jetty was monitored at a busy harbor in the North East of Scotland, adjacent to an important Atlantic salmon river. The main concern was with the impact of noise upon salmon migrating through the lower part of the river estuary. Pile driving was allowed to proceed subject to an agreed program of works to monitor sound levels and ensure least disturbance to salmon. Both percussive and vibratory pile driving took place. Sound-pres...

  7. Experimental study on uplift bearing capacity of micropiles by concreting method%灌注细石混凝土微型桩基础上拔试验研究

    Institute of Scientific and Technical Information of China (English)

    苏荣臻; 童瑞铭; 杨文智

    2012-01-01

    The field tests are carried out to study the uplift hearing mechanism and the uplift design method of micropiles by concreting method. The study shows: in this testing condition, the uplift hearing capacity of single pile is composed of the pile weight and the lateral friction ; under uplift load, the bearing load of the angle pile is maximum, the side pile is the second, and the middle pile is the minimum; the limit uplift bearing capacity of pile group could be obtained from the product of the limit bearing capacity of single pile, the pile number and the effect coefficient of the pile group, in the testing condition, the uplift effect coefficient of the pile group is 0.75.%通过现场真型试验,对灌注细石混凝土微型桩基础抗拔承栽机理及其抗拔承载力计算方法进行了研究。试验表明:在本次试验条件下,微型桩单桩抗拔承载力可由桩身自重和桩周侧摩阻力相加组成;由于承台对上拔荷载的重分配,在上拔荷栽作用下,角桩承力最大,边桩次之,中桩最小;微型桩群桩抗拔极限承载力可以通过单桩抗拔极限承载力乘以桩数和群桩效应系数计算得到.本次试验条件下.微型桩抗拔群桩效应系数选取0.75讲行计算.

  8. Finite Element Investigations on the Interaction between a Pile and Swelling Clay

    DEFF Research Database (Denmark)

    Kaufmann, Kristine Lee; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    This paper aims to investigate the interaction between a pile and a swelling soil modelled as a cohesive soil subjected to unloading. The investigations include analyses of the heave of the excavation level, shear stresses at the soil–pile interface and internal pile forces based on a case study...... of Little Belt Clay. The case study involves a circular concrete pile installed in clay immediately after an excavation. The influence of the swelling soil on the soil–pile interaction and the internal pile forces are analysed by solely observing the upper pile part positioned in the swelling zone...

  9. Numerical Simulation for the Soil-Pile-Structure Interaction under Seismic Loading

    Directory of Open Access Journals (Sweden)

    Lifeng Luan

    2015-01-01

    Full Text Available Piles are widely used as reinforcement structures in geotechnical engineering designs. If the settlement of the soil is greater than the pile, the pile is pulled down by the soil, and negative friction force is produced. Previous studies have mainly focused on the interaction of pile-soil under static condition. However, many pile projects are located in earthquake-prone areas, which indicate the importance of determining the response of the pile-soil structure under seismic load. In this paper, the nonlinear, explicit, and finite difference program FLAC3D, which considers the mechanical behavior of soil-pile interaction, is used to establish an underconsolidated soil-pile mode. The response processes of the pile side friction force, the pile axial force, and the soil response under seismic load are also analyzed.

  10. 实现桩土共同作用的机理及若干方法%Working mechanism and some realization methods of pile-soil interaction

    Institute of Scientific and Technical Information of China (English)

    周峰; 林树枝

    2012-01-01

    通常情况下,桩、土支承刚度差异显著,相同荷载水平下两者存在变形差,因此要实现桩土共同作用,必须要消除桩土的变形差,保证桩土的变形协调。在分析桩土共同作用机理的基础上,对现有桩土共同作用的实现方法和发展趋势进行归纳与总结并将其分为三大类:补偿位移法、刚度调整法以及预加位移法。其中,补偿位移法又包括摩擦桩复合桩基与刚性桩复合地基,刚度调整法主要为笔者提出的设置调节装置的端承桩复合桩基,预加位移法主要指桩顶设置柔性材料以及桩顶预留净空复合桩基。对上述每类所包含的具体方法进行了介绍,并对各自的适用条件、优缺点进行了对比与分析。%Significant differences on supporting stiffness usually exist between piles and soils,and differential settlement is formed at the same level of loads.In order to realize pile-soil interaction,the differential settlement must be eliminated to ensure deformation compatibility of piles and soils.Based on analyzing mechanism of pile-soil interaction,existing methods and future development trend were summarized and divided into three classes: method of deformation compensation,method of rigid adjusting and method of preadditive deformation.The method of deformation compensation included friction pile composite foundation and rigid pile composite foundation.The method of rigid adjusting included end bearing pile composite foundation.The method of preadditive deformation included composite pile foundation with gap or flexible materials at pile head.These methods were introduced,and the applicable conditions,advantages and disadvantages of above methods were compared and analyzed.

  11. Computerised analysis of sulphate action on model concrete piles

    Digital Repository Service at National Institute of Oceanography (India)

    Deshmukh, A.M.; Balasubramanian, S.; Venugopal, C.

    Sulphate action severely affects the durability of marine structures. It is imperative to study precisely the effects of magnesium sulphate on pile foundations in the marine environment. In the present paper an attempt is made to assess and analyse...

  12. 20051655 - Petronas, Capacity of Driven Piles Offshore Malaysia

    DEFF Research Database (Denmark)

    Augustesen, Anders; Andersen, Lars

    This document is the third of four notes concerning the vertical capacity of piles. It includes an assessment of the effect of previous static load testing upon the measured capacity, i.e. preshearing effects....

  13. 20051655 - Petronas, Capacity of Driven Piles Offshore Malaysia

    DEFF Research Database (Denmark)

    Augustesen, Anders

    This document is the second of four notes concerning the effects of time (in this case ageing) on the vertical capacity of piles. It includes a critical review of the relevant publications described in note a....

  14. As Traffic Piles Up, So Does Air Pollution

    Science.gov (United States)

    ... 160914.html As Traffic Piles Up, So Does Air Pollution To minimize exposure, researchers recommend shutting windows and ... Doing so can reduce your exposure to toxic air pollution from a traffic jam by up to 76 ...

  15. Lateral response of pile foundations in liquefiable soils

    Directory of Open Access Journals (Sweden)

    Asskar Janalizadeh

    2015-10-01

    Full Text Available Liquefaction has been a main cause of damage to civil engineering structures in seismically active areas. The effects of damage of liquefaction on deep foundations are very destructive. Seismic behavior of pile foundations is widely discussed by many researchers for safer and more economic design purposes. This paper presents a pseudo-static method for analysis of piles in liquefiable soil under seismic loads. A free-field site response analysis using three-dimensional (3D numerical modeling was performed to determine kinematic loads from lateral ground displacements and inertial loads from vibration of the superstructure. The effects of various parameters, such as soil layering, kinematic and inertial forces, boundary condition of pile head and ground slope, on pile response were studied. By comparing the numerical results with the centrifuge test results, it can be concluded that the use of the p-y curves with various degradation factors in liquefiable sand gives reasonable results.

  16. Airborne thermography of temperature patterns in sugar beet piles

    Science.gov (United States)

    Moore, D. G.; Bichsel, S.

    1975-01-01

    An investigation was conducted to evaluate the use of thermography for locating spoilage areas (chimneys) within storage piles and to subsequently use the information for the scheduling of their processing. Thermal-infrared quantitative scanner data were acquired initially on January 16, 1975, over the storage piles at Moorhead, Minnesota, both during the day and predawn. Photographic data were acquired during the day mission to evaluate the effect of uneven snow cover on the thermal emittance, and the predawn thermography was used to locate potential chimneys. The piles were examined the day prior for indications of spoilage areas, and the ground crew indicated that no spoilage areas were located using their existing methods. Nine spoilage areas were interpreted from the thermography. The piles were rechecked by ground methods three days following the flights. Six of the nine areas delineated by thermography were actual spoilage areas.

  17. Residual settlement calculation of geocell cushion over gravel piles

    Institute of Scientific and Technical Information of China (English)

    陈昌富; 杨宇; 肖淑君; 周志军

    2008-01-01

    The calculation of residual settlement of bidirectional reinforced composite foundation, which is composed of geocell cushion over gravel piles, was studied. The geocell cushion was modeled as a thin flexible plate with large deflection. Based on the Kirchhoff hypothesis, the governing differential equations and boundary conditions of the deformation of geocell cushion under working load were founded using von Karman method and solved by Galerkin method. On theses bases, the gravel piles and inter-pile soils were assumed as Winkler ground with variable spring stiffness so as to execute the approximate calculation of the residual settlement of the bidirectional reinforced composite foundation. The calculation method was verified by two laboratory experiments concerning settlement of embankments. One experiment was with just geocell cushion installed to treat the soft clay under embankments; another one was with both geocell cushion and gravel piles installed. The results show that the calculated settlement curve and the maximum settlement are closed to the observed ones.

  18. Piles, Tabs and Overlaps in Navigation among Documents

    DEFF Research Database (Denmark)

    Jakobsen, Mikkel Rønne; Hornbæk, Kasper Anders Søren

    2010-01-01

    Navigation among documents is a frequent, but ill supported activity. Overlapping or tabbed documents are widespread, but they offer limited visibility of their content. We explore variations on navigation support: arranging documents with tabs, as overlapping windows, and in piles. In an experim......Navigation among documents is a frequent, but ill supported activity. Overlapping or tabbed documents are widespread, but they offer limited visibility of their content. We explore variations on navigation support: arranging documents with tabs, as overlapping windows, and in piles....... In an experiment we compared 11 participants’ navigation with these variations and found strong task effects. Overall, overlapping windows were preferred and their structured layout worked well with some tasks. Surprisingly, tabbed documents were efficient in tasks requiring simply finding a document. Piled...... on document navigation and its support by piling....

  19. Processing Satellite Imagery To Detect Waste Tire Piles

    Science.gov (United States)

    Skiles, Joseph; Schmidt, Cynthia; Wuinlan, Becky; Huybrechts, Catherine

    2007-01-01

    A methodology for processing commercially available satellite spectral imagery has been developed to enable identification and mapping of waste tire piles in California. The California Integrated Waste Management Board initiated the project and provided funding for the method s development. The methodology includes the use of a combination of previously commercially available image-processing and georeferencing software used to develop a model that specifically distinguishes between tire piles and other objects. The methodology reduces the time that must be spent to initially survey a region for tire sites, thereby increasing inspectors and managers time available for remediation of the sites. Remediation is needed because millions of used tires are discarded every year, waste tire piles pose fire hazards, and mosquitoes often breed in water trapped in tires. It should be possible to adapt the methodology to regions outside California by modifying some of the algorithms implemented in the software to account for geographic differences in spectral characteristics associated with terrain and climate. The task of identifying tire piles in satellite imagery is uniquely challenging because of their low reflectance levels: Tires tend to be spectrally confused with shadows and deep water, both of which reflect little light to satellite-borne imaging systems. In this methodology, the challenge is met, in part, by use of software that implements the Tire Identification from Reflectance (TIRe) model. The development of the TIRe model included incorporation of lessons learned in previous research on the detection and mapping of tire piles by use of manual/ visual and/or computational analysis of aerial and satellite imagery. The TIRe model is a computational model for identifying tire piles and discriminating between tire piles and other objects. The input to the TIRe model is the georeferenced but otherwise raw satellite spectral images of a geographic region to be surveyed

  20. Experimental and Theoretical Research of Deformation of Vertically Loaded Displacement Piles in Sand Soil

    Directory of Open Access Journals (Sweden)

    Tautvydas Statkus

    2014-12-01

    Full Text Available The displacement piles are one of the oldest type of foundation not just in Lithuania, but also all over the world. Stiff, glacial origin sands lay not far from the ground surface in Lithuania as opposed to the rest of the Western Europe, therefore this kind of foundation is carried out into practice very often in our country. For geotechnical engineers it is very hard to decide which method should be applied, when there is no local experience. Five approaches are discussed on this paper and the results of three single piles’ tests are compared. The full scale single piles’ tests were carried out at the artificial bearing stratum pit. Piles’ diameter was 330 mm. The ratio of the piles’ depth and diameter were 3.3, 4.4 and 4.8. In conclusion of this paper the recommendations are given, which should be applied in different cases using mentioned above methods.

  1. Golden Herbs used in Piles Treatment: A Concise Report

    OpenAIRE

    Rajani Chauhan; Km. Ruby; Jaya Dwivedi

    2012-01-01

    Herbal medicine is also called phytomedicine. It is refers to using a plant's seeds, berries, roots, leaves, bark, or flowers for disease treatment.Herbs have many golden phytochemicals or secondary metabolites to treat disease. They have a long tradition of use outside of conventional medicine. Hemorrhoids or Piles treatment through Herbs has been effective and a golden treatment without any side-effects. There are some herbs which is useful in piles treatment such as Aesculus hippocastanum,...

  2. Jointless and Smoother Bridges: Behavior and Design of Piles

    OpenAIRE

    Frosch, Robert J; Chovichien, Voraniti; Durbin, Katrinna; Fedroff, David

    2006-01-01

    Integral abutment bridges have been used in the United States for decades. By eliminating expensive expansion joints, the piles supporting the end bent accommodate the total thermal movement of the bridge. Currently, integral bridges are designed based upon experience, and a rational design specification has not been developed. Furthermore, the interaction of the abutment, pile, and soil remains uncertain. A better understanding regarding the behavior of this system is needed. The objective o...

  3. Axial Non-linear Dynamic Soil-Pile Interaction - Keynote

    OpenAIRE

    Holeyman A.; Whenham V.

    2014-01-01

    This keynote lecture describes recent analytical and numerical advances in the modeling of the axial nonlinear dynamic interaction between a single pile and its embedding soil. On one hand, analytical solutions are developed for assessing the nonlinear axial dynamic response of the shaft of a pile subjected to dynamic loads, and in particular to vibratory loads. Radial inhomogeneity arising from shear modulus degradation is evaluated over a range of parameters and compared with those obtained...

  4. Review of the literature on leachates from coal storage piles

    Energy Technology Data Exchange (ETDEWEB)

    Davis, E.C.; Boegly, W.J. Jr.

    1978-01-01

    Runoff from coal storage piles associated with coal conversion or combustion facilities may represent a potential source of environmental pollution. This report is an assessment of existing information on coal pile leachate. The assessment indicates that few detailed studies have been conducted to date, and these are limited and the results are highly variable. More detailed long-range studies using various types of coal are recommended. These studies should be carried out both in the laboratory and in field-scale experiments.

  5. In-pile test of Qinshan PWR fuel bundle

    International Nuclear Information System (INIS)

    In-pile test of Qinshan Nuclear Power Plant PWR fuel bundle has been conducted in HWRR HTHP Test loop at CIAE. The test fuel bundle was irradiated to an average burnup of 25000 Mwd/tU. The authors describe the structure of (3 x 3-2) test fuel bundle, structure of irradiation rig, fuel fabrication, irradiation conditions, power and fuel burnup. Some comments on the in-pile performance for fuel bundle, fuel rod and irradiation rig were made

  6. Guidelines for the Protection of Steel Piles : Corrosive Marine Environment

    OpenAIRE

    Rhodes, Graham

    2011-01-01

    The corrosion of steel is a common phenomenon. In a marine environment, steel is corroded at an accelerated rate due to the atmospheric conditions. To combat this corrosion, steel piles are coated in order to protect them. As a major supplier of steel piles, Rautaruukki Oyj (Ruukki) commissioned this project in order to streamline their coating process. Currently Ruukki supplies a different coating system for almost every job; the aim of the project was to reduce the number of systems used to...

  7. Pile Structure Program, Projected Start Date : January 1, 2010 (Implementation).

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Chris; Corbett, Catherine [Lower Columbia River Estuary Partnership; Ebberts, Blaine [U.S. Army Corps of Engineers

    2009-07-27

    The 2008 Federal Columbia River Power System Biological Opinion includes Reasonable and Prudent Alternative 38-Piling and Piling Dike Removal Program. This RPA directs the Action Agencies to work with the Estuary Partnership to develop and implement a piling and pile dike removal program. The program has since evolved to include modifying pile structures to enhance their habitat value and complexity by adding large woody debris. The geographic extent of the Pile Structure Program (PSP) includes all tidally-influenced portions of the lower Columbia River below Bonneville Dam; however, it will focus on the mainstem. The overarching goal of the PSP is to enhance and restore ecosystem structure and function for the recovery of federally listed salmonids through the active management of pile structures. To attain this goal, the program team developed the following objectives: (1) Develop a plan to remove or modify pile structures that have lower value to navigation channel maintenance, and in which removal or modification will present low-risk to adjacent land use, is cost-effective, and would result in increased ecosystem function. (2) Determine program benefits for juvenile salmonids and the ecosystem through a series of intensively monitored pilot projects. (3) Incorporate best available science and pilot project results into an adaptive management framework that will guide future management by prioritizing projects with the highest benefits. The PSP's hypotheses, which form the basis of the pilot project experiments, are organized into five categories: Sediment and Habitat-forming Processes, Habitat Conditions and Food Web, Piscivorous Fish, Piscivorous Birds, and Toxic Contaminant Reduction. These hypotheses are based on the effects listed in the Estuary Module (NOAA Fisheries in press) and others that emerged during literature reviews, discussions with scientists, and field visits. Using pilot project findings, future implementation will be adaptively managed

  8. Comparing dynamic and static test results of bored piles

    OpenAIRE

    Long, Michael

    2007-01-01

    Due to increasing time, cost and transportation difficulties, Irish contractors are seeking an alternative to conventional static pile load tests. As a result several firms have adopted dynamic testing techniques to supplement and in some cases to replace conventional static tests. In order to assess the reliability of the systems and to address the concerns of owners and consulting engineers, a database comprising 43 pairs of static and dynamic tests on piles from 24 sites aro...

  9. Axial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  10. Teddy Bear Stories

    DEFF Research Database (Denmark)

    van Leeuwen, Theo; Caldas-Coulthardt, Carmen

    2014-01-01

    This paper presents a semiotic analysis of a key cultural artefact, the teddy bear. After introducing the iconography of the teddy bear, it analyses different kinds of stories to show how teddy bears are endowed with meaning in everyday life: stories from children's books, reminiscenses by adults...

  11. Axial Non-linear Dynamic Soil-Pile Interaction - Keynote

    Directory of Open Access Journals (Sweden)

    Holeyman A.

    2014-01-01

    Full Text Available This keynote lecture describes recent analytical and numerical advances in the modeling of the axial nonlinear dynamic interaction between a single pile and its embedding soil. On one hand, analytical solutions are developed for assessing the nonlinear axial dynamic response of the shaft of a pile subjected to dynamic loads, and in particular to vibratory loads. Radial inhomogeneity arising from shear modulus degradation is evaluated over a range of parameters and compared with those obtained by other authors and by a numerical radial discrete model simulating the pile and soil movements from integration of the laws of motion. New approximate non linear solutions for axial pile shaft behaviour developed from general elastodynamic equations are presented and compared to existing linear solutions. The soil non linear behaviour and its ability to dissipate mechanical energy upon cyclic loading are shown to have a significant influence on the mechanical impedance provided by the surrounding soil against pile shaft movement. The limitations of over-simplified modelling of pile response are highlighted.

  12. The Effects of Time on Soil Behaviour and Pile Capacity

    DEFF Research Database (Denmark)

    Augustesen, Anders

    this into account. This implies that the design methods used today do not in general make use of the full capacity of piles. This thesis is based on a number of scientific papers and reports that deal with elements of pile design and time effects in soils in general. With regard to pile design, focus is placed...... on estimation of the axial pile capacity by static design equations and especially the influence of time on pile capacity. In respect of time effects in soils in general focus is placed on observed time-dependent behaviour of soils and models developed to capture this behaviour. The thesis consists of two parts...... based on a set of static loading tests. In the literature it is suggested that the pile capacity increases with the logarithm to time after installation which is confirmed in this thesis. In continuation of this, it is analysed whether the magnitude of the set-up is related to the properties of the clay...

  13. PHC管桩接桩问题的检测%Detection of the PHC pipe pile joint of pile problems

    Institute of Scientific and Technical Information of China (English)

    陈军

    2009-01-01

    概括了低应变动测、高应变动测、静载荷试验及孔内摄像等方法检测PHC管桩时的优缺点,分析了管桩接桩问题产生的原因,进而提出了针对此问题的检测方案,从而避免因桩的接头问题引起的建筑物不均匀沉降.%The merits and drawbacks of low strain dynamic testing, dynamic high strain testing, dead load testing and down hole imaging todetect PHC pipe pile were generalized. The pipe pile joint of pile problems occurring reasons were analyzed, then the detected plan against to the problem was proposed, therefore avoided buildings uneven settlement provoked by pile joints problems.

  14. 后注浆灌注桩在某工程中的应用及经济分析%Application and Economic Analysis of Post-grouting Bored Concrete Pile in a Project

    Institute of Scientific and Technical Information of China (English)

    刘军; 洪峰

    2011-01-01

    Combined with the actual construction the principle and application of post-pressure grouting technology in pile tip and pile lateral of reinforced concrete bored cast-in pilate piles are introduced.There are many factors affecting pile foundation selection for construction works.Through the cost analysis and evaluation on the pile foundation of the construction works, some economic indicators for the selection of pile foundation under the present productive force and price level are gained.Which will be beneficial to improve the cost effectiveness and rationality of selection of it.The base-grouting treatment technique of bored concrete pile can improve the bearing capacity, so the application of this kind of pile become broad useage day by day.%结合工程实例,介绍了钢筋混凝土钻孔灌注桩桩端桩侧后压浆技术的原理及应用。影响建筑工程桩基选型的因素很多,通过典型工程桩基的造价分析与评价,得出当前生产力和物价水平条件下桩基选型的若干经济指标.有助于提高建筑工程桩基选型的经济性及合理性水平。由于灌注桩后注浆处理技术可使承载力显著提高.因而这种桩基日益得到广泛应用。

  15. Analysis on Compression Load Performance Detection of Steel Pipe Piles Supporting Port Bridge%某港区大桥基础钢管桩的抗压承载性能检测试验分析

    Institute of Scientific and Technical Information of China (English)

    朱良虎; 刘先鹏; 居炎飞; 易振友

    2012-01-01

    According to site high-strain dynamic detection test and vertical compression static test for the steel pipe piles supporting some port bridge, CAPWAPC method is applied and relevant geologic data are analyzed in order to draw load-settlement curve diagram of steel pipe pile axial compression test, determine ultimate vertical bearing capacity of steel pipe pile, draw the distribution curves diagram of pile axial force and pile side frictional resistance, analyze the clogging effect of steel pipe pile end, suggest clogging effect coefficient, and make a comprehensive evaluation on the integrity of the steel pipe pile by comparing and analyzing dynamic and static test results of foundation pile.%根据某港区大桥基础钢管桩的现场高应变动力检测试验和垂直抗压静载荷试验,在详细分析工程地质资料和采用CAPWAPC法试验结果的基础上,绘制钢管桩轴向抗压试验的荷载-沉降关系曲线,判定钢管桩基础的垂直极限承载力;绘制桩身轴力和桩侧摩阻力的分布曲线,分析钢管桩桩底的闭塞效应,给出闭塞效应系数的推荐值;通过桩基动态和静态试验结果的对比分析,综合评估钢管桩的完整性.

  16. ANALYTICAL SOLUTION AND ITS APPLICATION OF VERTICAL VIBRATION OF A FRICTION PILE IN SATURATED SOIL%饱和土中摩擦桩竖向振动解析解及应用

    Institute of Scientific and Technical Information of China (English)

    李强; 郑辉; 王奎华

    2011-01-01

    采用与频率相关的桩土接触面模型建立了三维轴对称条件下摩擦桩在饱和土中的竖向耦合振动模型,通过势函数分解法和分离变量法求解了饱和土动力固结方程,利用桩土耦合条件得到摩擦桩竖向振动解,对桩周剪应力分布、桩顶的频率和时域响应进行了参数研究.结果表明,桩底支承系数和桩土接触面动刚度对桩土荷载传递有明显影响,频率相关的阻尼系数可以有效地抑制桩顶速度幅频的高频发散现象.最后通过与基桩实测结果对比,表明该模型可以较好地与基桩完整性测试结果吻合.%A dynamic model of a friction pile embedded in saturated soil is established on the basis of interface model with a frequent-dependent damping between the pile and the soil. With the use of potential functions and a variable separation method, the pile dynamic response to an arbitrary vertical load is analytically derived in a closed form under the assumption of the imperfect contact between the pile and soil and an elastic bearing at the pile toe. Furthermore, a parametric study is conducted to find out the main features of the soil-pile interaction, as aresult, the bearing stiffness at pile toe and soil stiffness of the pile shaft have major effects on dynamic load transfer at the contact surface of the pile and soil. And frequent dependent damping of the contact surface can restrain high frequency divergence effectively. Finally, it is shown that the theoretical curves of the present solution are in good agreement with those obtained from pile integrity test.

  17. Part 1: Logging residues in piles - Needle loss and fuel quality. Part 2: Nitrogen leaching under piles of logging residues

    International Nuclear Information System (INIS)

    Part 1: Experimental piles were built in three geographical locations during May-Sept. 1989. Logging residues consisted of 95% spruce and 5% pine. Height of the piles varied between 80 and 230 cm. Needles were collected by placing drawers under 40 randomely chosen piles. The drawers were emptied every two weeks during the storage period. Natural needle loss was between 18 and 32% of the total amount of needles after the first two months of storage. At the end of the storage period, 24-42% of the needles had fallen down to the drawers. At the end of the experiment the total needle fall was 95-100% in the shaken piles. According to the results of this study piles smaller than 150 cm had the most effective needle fall. Piles should be placed on open places where the air and sun heat penetrate and dry them. Needles were the most sensitive fraction to variations in precipitation compared to the other components, such as branches. Piles usually dried quickly, but they also rewet easily. This was especially true in the smaller piles. The lowest moisture content was measured at the end of June. The ash content in needles varied between 4 and 8%. 16 refs., 15 figs. Part 2: Three field experiments were equipped with no-tension humus lysimeters. Pairs of lysimeters with the same humus/field layer vegetation material were placed in pairs, one under a pile of felling residues and another in the open clear felling. Leaching of nitrogen as well as pH and electric conductivity in the leachate was followed through sampling of the leachate at regular intervals. The results from the investigation show that: * the amount of leachate was higher in lysimeters in the open clear felling, * pH in the leachate was initially lower under piles of felling residues, * the amount of nitrogen leached was higher in the open clear felling. Thus, storing of felling residues in piles during the summer season did not cause any increase in nitrogen leaching, which had been considered to be a risk

  18. Preliminary report on coal pile, coal pile runoff basins, and ash basins at the Savannah River Site: effects on groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, E. [Westinghouse Savannah River Company, AIKEN, SC (United States)

    1997-04-28

    Coal storage piles, their associated coal pile runoff basins and ash basins could potentially have adverse environmental impacts, especially on groundwater. This report presents and summarizes SRS groundwater and soil data that have been compiled. Also, a result of research conducted on the subject topics, discussions from noted experts in the field are cited. Recommendations are made for additional monitor wells to be installed and site assessments to be conducted.

  19. Cryogenic Hybrid Magnetic Bearing

    Science.gov (United States)

    Meeks, Crawford R.; Dirusso, Eliseo; Brown, Gerald V.

    1994-01-01

    Cryogenic hybrid magnetic bearing is example of class of magnetic bearings in which permanent magnets and electromagnets used to suspend shafts. Electromagnets provide active control of position of shaft. Bearing operates at temperatures from -320 degrees F (-196 degrees C) to 650 degrees F (343 degrees C); designed for possible use in rocket-engine turbopumps, where effects of cryogenic environment and fluid severely limit lubrication of conventional ball bearings. This and similar bearings also suitable for terrestrial rotating machinery; for example, gas-turbine engines, high-vacuum pumps, canned pumps, precise gimbals that suspend sensors, and pumps that handle corrosive or gritty fluids.

  20. Parametric study on the effects of pile inclination angle on the response of batter piles in offshore jacket platforms

    Science.gov (United States)

    Aminfar, Ali; Ahmadi, Hamid; Aminfar, Mohammad Hossein

    2016-06-01

    Offshore jacket-type platforms are attached to the seabed by long batter piles. In this paper, results from a finite element analysis, verified against experimental data, are used to study the effect of the pile's inclination angle, and its interaction with the geometrical properties of the pile and the geotechnical characteristics of the surrounding soil on the behavior of the inclined piles supporting the jacket platforms. Results show that the inclination angle is one of the main parameters affecting the behavior of an offshore pile. We investigated the effect of the inclination angle on the maximum von Mises stress, maximum von Mises elastic strain, maximum displacement vector sum, maximum displacement in the horizontal direction, and maximum displacement in the vertical direction. The pile seems to have an operationally optimal degree of inclination of approximately 5°. By exceeding this value, the instability in the surrounding soil under applied loads grows extensively in all the geotechnical properties considered. Cohesive soils tend to display poorer results compared to grained soils.

  1. 水平静力荷载作用下桩伴侣工作性状有限元模拟及与无伴侣构造形式的比较分析%FINITE ELEMENT ANALYSIS OF COMPARATIVE PERFORMANCE OF LATERALLY LOADED PILE WITH OR WITHOUT PARTNER

    Institute of Scientific and Technical Information of China (English)

    薛江炜; 葛忻声; 杨勇; 蔡景珞

    2013-01-01

    Reference on lateral load test and numerical simulation of large diameter pipe pile by using cast-in-place concrete(PCC),finite element model of a single pile with or without pile partner under lateral load is established. Comparison calculations show that pile partner can ensure lateral loads delivering from pile cap to foundation soil, and double reduce stress and displacement of pile. Pile partner can also make some improvement on lateral bearing characters for the pile foundation with low cap even though the modulus of foundation soil is small. When pile partner is equipped,and the connection mode between pile cap and pile changing from rigid connection to hinge joint,pile body internal force can also be drastically reduced;and pile and pile caps by distance can only be considered to meet the requirement of vertical bearing capacity or optimization design of pile foundation stiffness to reduce differential settlement. Pillow is not necessary and can be cancelled in composite foundation when pile partner is applied. The height of pile partner has little influence on internal force and displacement of pile. Under rare earthquake action,pile partner may sacrifice firstly to keep pile perform well.%借鉴现浇混凝土大直径管桩(PCC 桩)水平承载足尺试验和数值模拟的成果,建立水平荷载作用下多个构造形式有无伴侣的单桩有限元数值模型。对比计算与分析表明,对于低承台桩基设置桩伴侣可确保承台向地基土传递水平荷载,成倍减小基桩的应力和位移;对于桩身范围地基土模量低的低承台桩基的水平承载性状也有一定的改善;配备桩伴侣后,将桩与承台的连接方式由刚接改为铰接也能大幅度减小桩身内力,桩顶与承台的距离可单纯考虑竖向承载力和变刚度调平基础底板沉降的需要;设置桩伴侣后可取消褥垫层;桩伴侣的高度变化对水平荷载作用下桩内力和位移影响很小;在罕遇

  2. Pile foundation engineering in calcareous soils%钙质砂土中的桩基础工程综述

    Institute of Scientific and Technical Information of China (English)

    周杨; 刘晓宇; 李世海

    2013-01-01

    桩基础广泛应用于钙质砂土这类高压缩性地基中。在总结钙质砂土的成因、分布特点、基本物理性质和力学特性的基础上,认为在钙质砂土地基中传统打入桩提供的承载力不能满足工程要求,并针对传统打入桩失败原因进行了分析。详细介绍了两种新型桩结构形式、施工方法、承载力特性及存在的问题,对两种新型桩进行了比较。总结了两种新型桩的优缺点,提出对新型桩形式的可能的改进方案。在总结已有研究的基础上,建议引入数值模拟方法配合试验研究的新思路。%Pile foundations are widely used in compressible soils such as calcareous sediments. Based on an introduction of the origin, distribution, basic physical properties and mechanical properties of calcareous soils, it is concluded that traditional driven piles are ineffective in calcareous soils and the reasons for it are analyzed. A review of the published literature pertaining to pile foundations in calcareous soils is summarized, and two new types of piles are described, along with their structural types, construction methods, bearing capacity characters, existing problems and comparison between them. Each method has its own advantages and disadvantages. Some improved schemes are proposed and new research approaches combing experiments with numerical simulation are suggested.

  3. 单桩承载力预测的PSO-Gompertz模型%PSO-Gompertz Model for Single Pile Capacity Prediction

    Institute of Scientific and Technical Information of China (English)

    杜勇立

    2012-01-01

    According to the biological growth law, the Gompertz function model is used to the forecast of single-pile ultimate load after the load transmission mechanism of piles is analyzed, the Particle Swarm Optimization for parameter estimation of the model is provided, the prediction effects of PSO-Gompertz model and double common forecast models are compared with each other based on casestudy. The results show that the growth process of pile bearing capacity usually experience the stages of begin, development, maturity and saturation; the load-settlement (Q-s) curve of piles under static load can be described by the Gompertz function; PSO-Gompertz model works better than the hyperbola and index ones in the forecast of singlepile ultimate load.%在对桩的荷载传递规律进行分析的基础上,运用生物生长观点将Gompertz函数模型用于单桩极限荷载的预测中,给出模型参数估计的粒子群(PSO)方法,并在实例分析的基础上将PSO-Gompertz模型与常用预测模型进行了对比.结果表明:在桩顶静荷载作用下,单桩承载力的发展经历了发生、发展、成熟并趋于饱和的生长过程;桩的荷载Q~沉降s曲线可用logistic函数描述;PSO-Gompertz模型比双曲线模型、指数模型有更高的预测精度.

  4. 软土地基挤扩支盘桩抗拔试验研究%Field Test on Uplift Behavior of Squeezed Branch Pile in Soft Soil Ground

    Institute of Scientific and Technical Information of China (English)

    张琰; 陈培

    2012-01-01

    The squeezed branch pile is a new type variable cross-section pile foundation, and it has the virtue of high bearing capability, low settlement, simple machinery. With regard to the soft soil foundation in the littoral of China, the vertical pulling static loading tests were carried out to obtain the ultimate bearing capacity. By testing the internal force of the pile, the distribution law of axial force is obtained; the load transfer mechanism and bearing capability are studied. Based on the test results, the squeezed branch pile has obvious advantages in bearing capability compared to the conventional pile, as well as economic benefits and wide application prospect.%挤扩支盘桩是近年来新兴的一种变截面桩型,具有承载力高、沉降小,施工机具简单等优点.针对我国沿海地区软土地基,开展了挤扩支盘桩的竖向抗拔静载荷试验,得到了极限抗拔承载力.通过试桩的桩身内力测试,得到桩身轴力的分布规律,研究了挤扩支盘桩的荷载传递机理和抗拔承载性能.试验结果表明,挤扩支盘桩的竖向抗拔承载力比普通直孔桩有明显提高,具有良好的经济性和广阔的应用前景.

  5. 水平偏心荷载下斜桩群桩受力性状的离心机模型试验%Centrifugal model tests on batter pile groups under eccentric lateral loads

    Institute of Scientific and Technical Information of China (English)

    顾明; 陈仁朋; 孔令刚; 陈云敏; 张浙杭

    2014-01-01

    A series of centrifugal model tests are conducted to investigate the behavior of pile groups in sand subjected to eccentric lateral loads, especially the role of batter pile groups in resisting lateral or eccentric loads. The preparation and the procedure of the tests are described. The test results reveal that the eccentric distance of the lateral loads will affect the lateral response of the pile groups to some extent within the experimental range, but have little effect on the torsional behavior of the pile groups. The bearing capacity of the plumb pile group under lateral loads with eccentric distance of 4.3D is higher than that of zero and 7.1D. The capacity of the batter pile groups subjected to lateral, eccentric or torsional loads is much higher than that of the plumb pile groups. Under the eccentric loads, the differences between the lateral displacements of individual piles within the batter pile groups are larger than those in the plumb pile groups, and they also increase with the eccentric distance of the lateral loads. The shear forces and lateral displacements at head of individual piles are different in direction. The axial forces of individual piles within the batter pile groups are dramatically larger than those in the plumb pile groups under the same load condition, which illustrates that batter pile groups can more effectively resist the lateral loads than the plumb pile groups by taking full advantages of the axial capacity of individual piles.%为研究斜桩群桩在水平偏心荷载下的受力性状,在砂土中开展了一系列离心机模型试验,着重对比了直桩群桩和斜桩群桩抵抗水平及偏心荷载的不同特性。详细介绍了模型试验的装置、方法以及内容。试验结果表明:水平荷载偏心距大小对群桩水平承载力有一定的影响,但是对群桩扭转承载力的影响较小。对于直桩群桩,在试验范围内小偏心距(4.3倍桩径)加载对应的水平承载力大

  6. Seismic response of tall building considering soil-pile-structure interaction

    Science.gov (United States)

    Han, Yingcai

    2002-06-01

    The seismic behavior of tall buildings can be greatly affected by non-linear soil-pile interaction during strong earthquakes. In this study a 20-storey building is examined as a typical structure supported on a pile foundation for different conditions: (1) rigid base, i.e. no deformation in the foundation: (2) linear soil-pile system; and (3) nonlinear soil-pile system. The effects of pile foundation displacements on the behavior of tall building are investigated, and compared with the behavior of buildings supported on shallow foundation. With a model of non-reflective boundary between the near field and far field, Novak’s method of soil-pile interaction is improved. The computation method for vibration of pile foundations and DYNAN computer program are introduced comprehensively. A series of dynamic experiments have been done on full-scale piles, including single pile and group, linear vibration and nonlinear vibration, to verify the validity of boundary zone model.

  7. Numerical Analysis of the Stability of Embankment Slope Reinforced with Piles

    Institute of Scientific and Technical Information of China (English)

    CUI Wei; ZHANG Zhigeng; YAN Shuwang

    2007-01-01

    The effects of stabilizing piles on the stability of an embankment slope are analyzed by numerical simulation. The shear strength reduction method is used for the analysis, and the soil - pile interaction is simulated with zero-thickness elasto-plastic interface elements. Effects of pile spacing and pile position on the safety factor of slope and the behavior of piles under these conditions are given. The numerical analysis indicates that the positions of the pile have significant influence on the stability of the slope, and the pile needs to be installed in the middle of the slope for maximum safety factors. In the end, the soil arching effect closely associated with the space between stabilizing piles is analyzed. The results are helpful for design and construction of stabilizing piles.

  8. Experimental Investigations of Tension Piles in Sand Subjected to Static and Cyclic Loading

    DEFF Research Database (Denmark)

    Thomassen, Kristina

    The present thesis regards the behavior of the piles in jacket pile foundations used for offshore wind turbines. The piles are often loaded in tension because of the combination of wind and wave conditions and the low self-weight of the wind turbine. The repeated cyclic loading can lead...... to accumulated upwards displacement of the piles and, thus, undesired deflection of the wind turbine structure. This study concerns the effect of cyclic loading on a pile installed in dense sand and loaded in tension. A new laboratory test setup was constructed to make these pile load tests. The thesis discusses...... the advantages and disadvantages of the test setup. The results of cyclic loading tests showed that the loading conditions are very important for the behavior of piles. Some wind and wave conditions can be beneficial and increase the pile capacity while other conditions can be damaging and reduce the pile...

  9. Seismic response of tall building considering soil-pile-structure interaction

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The seismic behavior of tall buildings can be greatly affected by non-linear soil-pile interaction during strongearthquakes. In this study a 20-storey building is examined as a typical structure supported on a pile foundation for differentconditions: (1) rigid base, i.e. no deformation in the foundation: (2) linear soil-pile system; and (3) nonlinear soil-pile system.The effects of pile foundation displacements on the behavior of tall building are investigated, and compared with the behavior ofbuildings supported on shallow foundation. With a model of non-reflective boundary between the near field and far field,Novak's method of soil-pile interaction is improved. The computation method for vibration of pile foundations and DYNANcomputer program are introduced comprehensively. A series of dynamic experiments have been done on full-scale piles,including single pile and group, linear vibration and nonlinear vibration, to verify the validity of boundary zone model.

  10. Development technology of rigidity-drain pile and numerical analysis of its anti-liquefaction characteristics

    Institute of Scientific and Technical Information of China (English)

    刘汉龙; 陈育民; 赵楠

    2008-01-01

    Pile foundation is widely used in the offshore engineering. The pile can be seriously destroyed by the soil liquefaction during strong earthquakes. The potentials of liquefaction and damages of pile foundation due to the liquefaction can be reduced by the implementation of the drainage in the liquefiable foundation. A patented pile technology, named rigidity-drain pile, was introduced. The partial section of the pile body was filled by materials with higher penetrability which forms some effective drainage channels in the pile. The principles and construction methods were presented. 3D models for both rigidity-drain pile and ordinary pile were built in FLAC3D code. The dynamic loadings were applied on the bottom of the model. According to the numerical results, in the case of the rigidity-drain pile, the water in the relevant distance range around the pile flows toward the pile drainage, the contour of the pore pressure shows a funnel form. Contrast to the ordinary pile, the rigidity-drain pile can dissipate the accumulated excess pore water, maintain effective stress and obviously reduce the possibility of surrounding soil liquefaction.

  11. Analytical model of vertical vibrations in piles for different tip boundary conditions: parametric study and applications

    Institute of Scientific and Technical Information of China (English)

    Ning WANG; Kui-hua WANG; Wen-bing WU

    2013-01-01

    In this paper,a model named fictitious soil pile was introduced to solve the boundary coupled problem at the pile tip.In the model,the soil column between pile tip and bedrock was treated as a fictitious pile,which has the same properties as the local soil.The tip of the fictitious soil pile was assumed to rest on a rigid rock and no tip movement was allowed.In combination with the plane strain theory,the analytical solutions of vertical vibration response of piles in a frequency domain and the corresponding semi-analytical solutions in a time domain were obtained using the Laplace transforms and inverse Fourier transforms.A parametric study of pile response at the pile tip and head showed that the thickness and layering of the stratum between pile tip and bedrock have a significant influence on the complex impedances.Finally,two applications of the analytical model were presented.One is to identify the defects of the pile shaft,in which the proposed model was proved to be accurate to identify the location as well as the length of pile defects.Another application of the model is to identify the sediment thickness under the pile tip.The results showed that the sediment can lead to the decrease of the pile stiffness and increase of the damping,especially when the pile is under a low frequency load.

  12. Seismic Demands for Pile-Supported Wharf Structures with Batter Piles

    Directory of Open Access Journals (Sweden)

    Rouhollah Amirabadi

    2012-09-01

    Full Text Available This study develops an optimal Probabilistic Seismic Demand Model (PSDM for pile-supported wharves whit batter plies. Four bins with twenty non-near-field ground motions and three typical pile-supported wharf structures from western United States ports are used to determine an optimal PSDM by using Probabilistic Seismic Demand Analysis (PSDA. PSDA is used to compute the relationship between Engineering Demand Parameters (EDPs and earthquake Intensity Measures (IMs. An optimal PSDM should be practical, sufficient, effective and efficient-all tested through several IM-EDP pairs. It has been found that for these types of structures, the optimal model comprises a spectral IM, such as spectral acceleration and one of several EDPs. These EDPs are considered for local (moment curvature ductility factor, intermediate (displacement ductility factor and horizontal displacement of embankment and global (differential settlement between deck and behind land response quantities. The considered PSDMs are a critical component in performance-based seismic design and seismic risk assessment. Results can be used in probabilistic framework for performance-based design developed by Pacific Earthquake Engineering Research (PEER center.

  13. Characterization of Odorant Compounds from Mechanical Aerated Pile Composting and Static Aerated Pile Composting.

    Science.gov (United States)

    Kumari, Priyanka; Lee, Joonhee; Choi, Hong-Lim

    2016-04-01

    We studied airborne contaminants (airborne particulates and odorous compounds) emitted from compost facilities in South Korea. There are primarily two different types of composting systems operating in Korean farms, namely mechanical aerated pile composting (MAPC) and aerated static pile composting (SAPC). In this study, we analyzed various particulate matters (PM10, PM7, PM2.5, PM1, and total suspended particles), volatile organic compounds and ammonia, and correlated these airborne contaminants with microclimatic parameters, i.e., temperature and relative humidity. Most of the analyzed airborne particulates (PM7, PM2.5, and PM1) were detected in high concentration at SAPC facilities compered to MAPC; however these differences were statistically non-significant. Similarly, most of the odorants did not vary significantly between MAPC and SAPC facilities, except for dimethyl sulfide (DMS) and skatole. DMS concentrations were significantly higher in MAPC facilities, whereas skatole concentrations were significantly higher in SAPC facilities. The microclimate variables also did not vary significantly between MAPC and SAPC facilities, and did not correlate significantly with most of the airborne particles and odorous compounds, suggesting that microclimate variables did not influence their emission from compost facilities. These findings provide insight into the airborne contaminants that are emitted from compost facilities and the two different types of composting agitation systems. PMID:26949962

  14. 高临界循环荷载水平下钻孔桩的抗拔性状分析%Uplift behaviors of bored piles subjected to high critical cyclic loading level

    Institute of Scientific and Technical Information of China (English)

    张忠苗; 谢志专; 赵玉勃; 李慧明

    2012-01-01

    为了研究抗拔桩在循环加载过程中桩身的性状,选取杭州萧山某工地两根抗拔桩作为试桩进行循环加载试验.在抗拔桩桩身埋设钢筋应力计,测量循环加载过程中桩身应力的变化情况;在桩身预埋钢管,测量桩顶及桩端上拔量.通过对桩身应力及桩顶、桩端上拔量的分析,研究循环加载对抗拔桩承载力及上拔量的影响.综合分析抗拔桩承受循环荷载时的桩顶、桩端上拔量、桩身轴力以及桩侧摩阻力分布可知,当抗拔桩承受循环荷载时,且临界循环荷载水平较大(接近或者达到1),抗拔桩经过2~3次循环加载后就发生破坏,其研究结果可供其他类似工程参考.%In order to study the behaviors of uplift pile subject to cyclic load, cyclic loading tests are carried out on two uplift piles at Xiaoshan, Hangzhou. Stress gauges and steel pipes are pre-buried in the test pile to measure the changes of pile shaft stress and the pull-out amount of both pile tip and pile head. Through the analysis of the pile shaft stress and the pull-out amount, the influence of cyclic load on bearing capacity and pull-out amount are studied. Comprehensive analysis of the pull-out amount, pile shaft force and pile side friction, it is drawn a conclusion that the uplift pile damaged after two or three cycles when uplift pile subjects to cyclic load, and the critical cyclic load level is close to 1.

  15. INTERACTION OF A LONG SINGLE PILE THAT HAS A DOUBLE-LAYER BASE WITH ACCOUNT FOR COMPRESSIBILITY OF THE PILE SHAFT

    Directory of Open Access Journals (Sweden)

    Ter-Martirosyan Zaven Grigor'evich

    2012-07-01

    The authors provide their solution to the problem of interaction of a long compressible pile that has a double-layer linear deformable base. The paper demonstrates that taking account of compressible properties of the pile material leads to qualitatively new distribution of shearing stresses over the surface of a cylindrical pile. It is noteworthy that increase of the pile length and stiffness of the upper section of the base raise the share of the load perceived by the surface of the pile. Besides, in particular conditions of the soil environment, the load perceived by the lower section of the base may reach approximately 20-30 % of the total load.

  16. WAVE CURRENT FORCES ON THE PILE GROUP OF BASE FOUNDATION FOR THE EAST SEA BRIDGE, CHINA

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis of the two structures of the bridge foundation designed for the East Sea Bridge, the wave current forces on four types of oblique piles, the pile group and the single piles at different positions in the pile group considering the effect of the super structures were experimentally investigated. The relationship between the wave current forces and the associated wave parameters, and the comparison of the wave current forces on the pile groups and the single piles were systematically analyzed. The group effectiveness and the reduction coefficient for the wave current forces on the group were examined for engineering design.

  17. Application of post grouting technology in pile foundation engineering of seawater cooling tower%后注浆技术在海水冷却塔桩基工程中的应用

    Institute of Scientific and Technical Information of China (English)

    吴涨器

    2016-01-01

    本文结合工程实例,介绍了后注浆工艺的加固机理和施工工艺,并根据工程试验和监测结果,阐述了后注浆工艺可以改善冲孔灌注桩的桩端土体强度,提高单桩竖向承载力,减少桩基沉降量。%Combined with engineering examples,this article introduces the reinforcement mechanism and construction technology after Grouting,and according to the engineering test and monitoring results;and it describes the process can be improved grouting bored pile end soil strength,improved the vertical bearing capacity of single pile and reduced the pile foundation settlement.

  18. Optimal Synchronizability of Bearings

    OpenAIRE

    Araújo, N. A. M.; Seybold, H.; Baram, R. M.; Herrmann, H. J.; Andrade, J. S.

    2013-01-01

    Bearings are mechanical dissipative systems that, when perturbed, relax toward a synchronized (bearing) state. Here we find that bearings can be perceived as physical realizations of complex networks of oscillators with asymmetrically weighted couplings. Accordingly, these networks can exhibit optimal synchronization properties through fine tuning of the local interaction strength as a function of node degree [Motter, Zhou, and Kurths, Phys. Rev. E 71, 016116 (2005)]. We show that, in analogy...

  19. Bear Spray Safety Program

    Science.gov (United States)

    Blome, C.D.; Kuzniar, R.L.

    2009-01-01

    A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

  20. Ground Vibration Isolation of Multiple Scattering by Using Rows of Tubular Piles as Barriers

    Directory of Open Access Journals (Sweden)

    Miao-miao Sun

    2014-01-01

    Full Text Available A new formal solution for the multiple scattering of plane harmonic waves by a group of arbitrary configuration tubular piles in an elastic total space is derived. Each order of scattering satisfies prescribed boundary conditions at the interface of tubular piles, which is delivered as the sum of incident and scattering waves. The first order performs the scattering wave by each scattered pile and the subsequent orders resulted from the excitation of each pile of first order of scattering from the remaining tubular piles. Advanced scattering orders can be regarded as the same manners. Several series of scattering coefficients are figured out with the aids of addition theorem so that the exact steady-state solution for the scattered displacement and stress is obtained. Particularly, when internal diameter of tubular piles tends to be infinitely small, it degenerates to a solid pile problem. By imposing the normalized displacement amplitudes and transmissibility indices, the influences of specific parameters such as scattering orders, internal and external diameter ratio of piles, pile material rigidity, position and distances between tubular pile and pile rows, and pile numbers are discussed. Certain recommended conclusions have been drawn as the guidelines of practical engineering design for discontinuous barrier of tubular piles.

  1. Bearing restoration by grinding

    Science.gov (United States)

    Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

    1976-01-01

    A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

  2. Structural design of neptunium-bearing assembly for transmutation research

    International Nuclear Information System (INIS)

    To study the irradiation performance of the long-life nuclide and to lay a foundation for the 'separation-transmutation' advanced fuel cycle technology, an experimental neptunium-bearing assembly is designed on the basis of the standard fuel assembly of CEFR. In this paper, design principles and structure of the experimental neptunium-bearing assembly are explained in detail. The design analysis and validation are briefly introduced. The design of the experimental assembly can meet the demand of irradiation test. Up to now, the out-of-pile hydraulic test is under way and the manufacture of the assembly is nearly completed. It is to be irradiated in the first row of stainless steel reflector assemblies for about 240 effective full power days. (authors)

  3. X-ray spectroscopy around the pile-up region

    CERN Document Server

    Sharma, Gaurav; Kumar, Basu; Puri, Nitin Kumar; Nandi, Tapan

    2015-01-01

    We report a pile-up rejection technique based on X-ray absorption concept of Beer-Lambert law for measuring true events in the pile-up region. We have detected a four orders times weaker peak in the pile-up region. This technique also enables one to resolve the weak peaks adjacent to an intense peak provided the latter lies in the lower energy side, and the peaks are at least theoretically resolvable by the detector used. We have resolved such peaks by reducing the intensity ratios in our experiment. The technique allows us to obtain the actual intensities of the observed peaks to have been measured without any attenuator. The possible applications of this technique can be to study the physics of two electron one-photon transition as well as the properties of projectile-like or target-like ions.

  4. Seismic soil-structure interaction of foundations with large piles

    International Nuclear Information System (INIS)

    In seismic regions with soft soil deposits subjected to ground surface subsidence, there is the necessity to support the weight of constructions on large diameter piles or piers hearing on deep firm strata. To justify the action of these elements working under flexo compression and shear, it is necessary to perform calculations of soil pile interaction from a practical engineering point of view and estimate the order of magnitude of the forces and displacements to which these elements will be subjected during the seismic action assigned to the foundation. In this paper we defined a pier as a large diameter pile constructed on site. Furthermore, in the seismic analysis it is necessary to evaluate the seismic pore water pressure to learn on the effective seismic soil stresses close to the ground surface. (author)

  5. Vertical and lateral capacity of screw anchor piles

    Energy Technology Data Exchange (ETDEWEB)

    Law, D.J.; Tweedie, R.W.; Harris, M.C. [Thurber Engineering Ltd., Edmonton, AB (Canada); Niedermaier, J. [Alberta Anchor Inc., Calgary, AB (Canada)

    1996-09-01

    Test programs were conducted to investigate the deformation behaviour of screw anchors during loading. Screw anchors are used in foundation applications for transmission towers and retaining walls, as well as for foundation elements for buildings, pipe racks, storage tanks and equipment. Screw anchor piles were installed at a site near Fort Saskatchewan, at a site underlain by typical stiff glacial soils. Single and multi-helix screw anchors with helix diameters up to 381 mm were tested in compression and tension. Lateral load tests were conducted on screw anchors with shaft diameters ranging from 114 mm to 273 mm. Results from the study showed that vertical and horizontal loads can be carried by screw anchor piles that are comparable with those achieved with driven steel piles, but screw anchors are easier to install, and can be more cost effective in some cases. 4 refs., 3 tabs., 4 figs.

  6. Probabilistic Assessment for Seismic Performance of Pile-Supported Wharves

    Directory of Open Access Journals (Sweden)

    Hamid Heidary Torkamani

    2013-03-01

    Full Text Available The main objective of this study is to investigate the influence of uncertainties associated with the material properties on the seismic performance of pile-supported wharves. For this purpose a two-dimensional finite difference model, representing typical pile-supported wharf structures from western United States has been constructed using software FLAC2D. Incremental dynamic analysis has been applied to evaluate the response of wharf structure under different levels of seismic loading. The uncertainties at both structural and geotechnical parameters have been investigated using a tornado diagram and a first-Order Second-Moment (FOSM analysis. It has been found that the uncertainties at the dead load of structure, friction angle of rock fill and the porosity of rock fill contribute most to the variability of the displacement ductility factor of the pile-supported wharf structures. Based on the results, design considerations have been provided.

  7. Improved Design Basis for Laterally Loaded Large Diameter Pile

    DEFF Research Database (Denmark)

    Leth, Caspar Thrane

    the structure and the productivity of the turbine. Current design practice for monopiles are based on p-y curves developed for slender piles with a diameter of 0.6 m. The focus on the structure stiffness has entailed a significant research on the soil-structure interaction for large diameter monopiles...... diameter, depth and soil strength, and increase of each these will give an increase in stiffness. • Cyclic response of a lateral loaded pile is depended on the characteristics of the cyclic load. Behaviour of a monopile is a classic soil-structure interaction problem depending on the pile stiffness and the...... expected development of offshore wind farms is towards larger farms, larger turbines and larger water depths. Monopiles have been applied widely and it is of interest to investigate the possibilities to further optimize the design and in particular the modelling of the soil-structure interaction. The...

  8. The Strength of Regolith and Rubble Pile Asteroids

    CERN Document Server

    Sánchez, Paul

    2013-01-01

    We explore the hypothesis that, due to small van der Waals forces between regolith grains, the strength of small rubble pile asteroids is constant. This creates a scale dependence, with relative strength increasing as size decreases. This counters classical theory that rubble pile asteroids should behave as scale-independent cohesionless collections of rocks. We explore a simple model for asteroid strength that is based on these weak forces, validate it through granular mechanics simulations and comparisons with properties of lunar regolith, and then show its implications and ability to explain and predict observed properties of small asteroids in the NEA and Main Belt populations. A conclusion is that the population of rapidly rotating asteroids consists of both distributions of smaller grains (i.e., rubble piles) and of monolithic boulders whose surfaces may still retain a size distribution of finer grains, potentially of size up to centimeters.

  9. Identification of Defects in Piles Through Dynamic Testing

    Science.gov (United States)

    Liao, Shutao T.; Roesset, Jose M.

    1997-04-01

    The objective of this work was to evaluate the theoretical capabilities of the non-destructive impact-response method in detecting the existence of a single defect in a pile, its location and its length. The cross-section of the pile is assumed to be circular and the defects are assumed to be axisymmetric in geometry. As mentioned in the companion paper, special codes utilizing one-dimensional (1-D) and three-dimensional (3-D) axisymmetric finite element models were developed to simulate the responses of defective piles to an impact load. Extensive parametric studies were then performed. In each study, the results from the direct use of time histories of displacements or velocities and the mechanical admittance (or mobility) function were compared in order to assess their capabilities. The effects of the length and the width of a defect were also investigated using these methods. Int. J. Numer. Anal. Meth. Geomech., vol. 21, 277-291 (1997)

  10. Design of Jetty Piles Using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Yongjei Lee

    2014-01-01

    Full Text Available To overcome the complication of jetty pile design process, artificial neural networks (ANN are adopted. To generate the training samples for training ANN, finite element (FE analysis was performed 50 times for 50 different design cases. The trained ANN was verified with another FE analysis case and then used as a structural analyzer. The multilayer neural network (MBPNN with two hidden layers was used for ANN. The framework of MBPNN was defined as the input with the lateral forces on the jetty structure and the type of piles and the output with the stress ratio of the piles. The results from the MBPNN agree well with those from FE analysis. Particularly for more complex modes with hundreds of different design cases, the MBPNN would possibly substitute parametric studies with FE analysis saving design time and cost.

  11. Testing of Laterally Loaded Rigid Piles with Applied Overburden Pressure

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Foglia, Aligi; Ibsen, Lars Bo

    2012-01-01

    Small-scale tests have been conducted for the purpose of investigating the quasi-static behaviour of laterally loaded, non-slender piles installed in cohesionless soil. For that purpose, a new and innovative test setup has been developed. The tests have been conducted in a pressure tank such that......Small-scale tests have been conducted for the purpose of investigating the quasi-static behaviour of laterally loaded, non-slender piles installed in cohesionless soil. For that purpose, a new and innovative test setup has been developed. The tests have been conducted in a pressure tank...... such that it was possible to apply an overburden pressure to the soil. Hereby, the traditional uncertainties related to low effective stresses for small-scale tests has been avoided. A scaling law for laterally loaded piles has been proposed based on dimensional analysis. The novel testing method has been validated against...

  12. Grouting Control for Deep-Water Jacket Skirt Pile

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing; ZHANG Jianxin; XU Lianjiang

    2006-01-01

    Deep-water jacket skirt pile grouting is a critical step in ocean platform construction. Because of the complexity of the skirt pile structure and grouting pipeline, the calculation of grouting pressure and the control of output pressure are involved. Beginning with the jacket skirt pile grouting construction scheme, grouting pressure is estimated on the basis of engineering fluid mechanics theory and variable frequency control technique. Programmable logic controller is the center of grouting pressure control system, which accomplishes the flow control of cement buffer tank water buffer tank, additive buffer tank, cement metering tank, water metering tank, additive metering tank, mixer and agitator. Based on PROFIBUS-DP network, the output pressure of the slurry pump is controlled by the inverter. This method has been applied successfully in JZ20-2 Nor. high spot jacket platform construction.

  13. Cumulative Damage in Strength-Dominated Collisions of Rocky Asteroids: Rubble Piles and Brick Piles

    Science.gov (United States)

    Housen, Kevin

    2009-01-01

    Laboratory impact experiments were performed to investigate the conditions that produce large-scale damage in rock targets. Aluminum cylinders (6.3 mm diameter) impacted basalt cylinders (69 mm diameter) at speeds ranging from 0.7 to 2.0 km/s. Diagnostics included measurements of the largest fragment mass, velocities of the largest remnant and large fragments ejected from the periphery of the target, and X-ray computed tomography imaging to inspect some of the impacted targets for internal damage. Significant damage to the target occurred when the kinetic energy per unit target mass exceeded roughly 1/4 of the energy required for catastrophic shattering (where the target is reduced to one-half its original mass). Scaling laws based on a rate-dependent strength were developed that provide a basis for extrapolating the results to larger strength-dominated collisions. The threshold specific energy for widespread damage was found to scale with event size in the same manner as that for catastrophic shattering. Therefore, the factor of four difference between the two thresholds observed in the lab also applies to larger collisions. The scaling laws showed that for a sequence of collisions that are similar in that they produce the same ratio of largest fragment mass to original target mass, the fragment velocities decrease with increasing event size. As a result, rocky asteroids a couple hundred meters in diameter should retain their large ejecta fragments in a jumbled rubble-pile state. For somewhat larger bodies, the ejection velocities are sufficiently low that large fragments are essentially retained in place, possibly forming ordered "brick-pile" structures.

  14. Difficulties and measures of driving super long piles in Bohai Gulf

    Directory of Open Access Journals (Sweden)

    Shuwang Yan

    2015-03-01

    Full Text Available Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build up in such a high level that hydraulic fracturing in the soil round the pile may take place, which will cause the soil to consolidate much faster during pile extension period. Consequently, after pile extension, the soil strength will recover to some extent and the driving resistance will increase considerably, which makes restarting driving the pile very difficult and even causes refusal. A finite element (FE analysis procedure is presented for judging the risk of refusal by estimating the blow counts after pile extension, in which the regain of soil strength is considered. A case analysis in Bohai Gulf is performed using the proposed procedure to explain the pile refusal phenomenon.

  15. Dynamic stiffness of pile groups in a multilayered soil. Part 1

    International Nuclear Information System (INIS)

    For evaluating the dynamic stiffness of the pile group foundations, forced vibration tests are executed on pile group foundation models. Two types of test models are used, one is a single pile model and the other a four-pile model. Dividing the tests into 4 steps, the forced vibration tests are performed. Step 1 is for the single pile model, and steps 2 to 4 are for the four-pile model. In step 2 and step 3, the gap effects between the foundation bottom and the ground surface are examined. In step 4, the backfill effects are obtained. Based on the test results, the pile group effects, the gap effects and the backfill effects on the dynamic characteristics of the pile group foundations are described in this paper

  16. Numerical Analysis of Interaction Between Pile-Supported Pier and Bank Slope

    Institute of Scientific and Technical Information of China (English)

    王年香

    2001-01-01

    Two- and three-dimensional finite element analysis programs for pile-soil interaction are compiled. Duncan-Chang's Model is used. The construction sequence of the pier is modeled. The pile-soil interface element is used. The influence of the combination type of piles on the deformation of bank slope and pile behaviour is analyzed. Different designs of a pile-supported pier are compared thoroughly. Calculation results show that the stresses and displacements of the pile are directly related to the distance from the bank slope and the direction of inclination. An inclined prop pile set in the rear platform would remarkably reduce the stresses of piles and the displacement of the pier.

  17. AN ANALYTICAL SOLUTION TO LONGITUDINAL VIBRATION OF A PILE OF ARBITRARY SEGMENTS WITH VARIABLE MODULUS

    Institute of Scientific and Technical Information of China (English)

    Wang Teng; Wang Kuihua; Xie Kanghe

    2001-01-01

    The vibration problem of a pile of arbitrary segments with variable modulus under exciting force is established, in which the influence of the soil under pile toe and the surroundings is taken into account. With Laplace transforms, the transmit functions for velocity and displacement of pile are derived. Furthermore, in terms of the convolution theorem and inversed Laplace transform, an analytical solution for the time domain response of a pile subjected to a semi-sine impulse is developed,which is the theoretical basis of the sonic method in pile integrity testing. Based on the solution, the vibration properties of pile with sharp or continuous modulus are studied. The validity of this approach is verified through fidd dynamic tests on some engineering piles. It shows that the theoretical prediction and the response of the pile are in good agreement.

  18. CFG桩在软土地基加固中的应用%Application of CFG pile in reinforcing soft soil foundation

    Institute of Scientific and Technical Information of China (English)

    张静

    2012-01-01

    This article inquires the reinforcing mechanism of CFG pile,introduces the application of CFG pile in reinforcing soft soil foundation,and respectively expounds construction technology and procedures and matters needing attention in construction,with a view to guide engineering practice and to improve the bearing capacity and stability of the foundation.%探讨了CFG桩的加固机理,介绍了CFG桩在软土地基加固中的应用,分别将其施工工艺流程和施工注意事项作了分析说明,以指导工程实践,提高地基承载能力和稳定性。

  19. Golden Herbs used in Piles Treatment: A Concise Report

    Directory of Open Access Journals (Sweden)

    Rajani Chauhan

    2012-12-01

    Full Text Available Herbal medicine is also called phytomedicine. It is refers to using a plant's seeds, berries, roots, leaves, bark, or flowers for disease treatment.Herbs have many golden phytochemicals or secondary metabolites to treat disease. They have a long tradition of use outside of conventional medicine. Hemorrhoids or Piles treatment through Herbs has been effective and a golden treatment without any side-effects. There are some herbs which is useful in piles treatment such as Aesculus hippocastanum, Allium cepa, Bergenia ligulata, Bergenia ciliata, Bergenia stracheyi, Hamamelis virginiana Ruscus aculeatus, Terminalia chebula Vaccinium myrtillus, Verbascum thapus etc.

  20. Effects of Impulsive Pile-Driving Exposure on Fishes.

    Science.gov (United States)

    Casper, Brandon M; Carlson, Thomas J; Halvorsen, Michele B; Popper, Arthur N

    2016-01-01

    Six species of fishes were tested under aquatic far-field, plane-wave acoustic conditions to answer several key questions regarding the effects of exposure to impulsive pile driving. The issues addressed included which sound levels lead to the onset of barotrauma injuries, how these levels differ between fishes with different types of swim bladders, the recovery from barotrauma injuries, and the potential effects exposure might have on the auditory system. The results demonstrate that the current interim criteria for pile-driving sound exposures are 20 dB or more below the actual sound levels that result in the onset of physiological effects on fishes.

  1. Centrifuge modelling of a laterally cyclic loaded pile

    DEFF Research Database (Denmark)

    Klinkvort, Rasmus Tofte; Leth, Caspar Thrane; Hededal, Ole

    2010-01-01

    A total number of 9 static and 6 cyclic centrifuge tests on laterally loaded piles in very dense, dry sand was erformed. The prototype dimensions of the piles were 1 meter in diameter and penetration depths varying from 6 to 10 meters. The static tests were used to investigate the initial subgrade...... reaction modulus and as a reference for cyclic tests. For the cyclic tests the accumulation of deflections and the change in secant stiffness of the soil from repetitive loading were investigated. From all the tests carried out accumulations of deflections were seen. rom the centrifuge tests it was seen...

  2. Testing of Laterally Loaded Rigid Piles with Applied Overburden Pressure

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo; Foglia, Aligi

    2015-01-01

    Small-scale tests have been conducted to investigate the quasi-static behaviour of laterally loaded, non-slender piles installed in cohesionless soil. For that purpose, a new and innovative test setup has been developed. The tests have been conducted in a pressure tank such that it was possible...... to apply an overburden pressure to the soil. As a result of that, the traditional uncertainties related to low effective stresses for small-scale tests have been avoided. A normalisation criterion for laterally loaded piles has been proposed based on dimensional analysis. The test results using the novel...

  3. 软土地区预应力管桩偏位原因分析及处理%Cause Analysis and Treatment of Deviated Prestressed Pipe Piles in Soft Soil

    Institute of Scientific and Technical Information of China (English)

    吴映栋; 党姣梅; 颜潇潇

    2014-01-01

    预应力管桩成桩质量好,承载力高,基础造价低,在江浙地区应用广泛。但在复杂地质情况下,特别是宁波软土地区,极易出现管桩偏位、断桩、斜桩等现象。结合工程实例,分析了预应力管桩产生偏位的原因,介绍了预应力管桩偏位的处理方法:准确测量偏位情况、低应变动测确定桩身损伤情况、根据管桩偏位及损伤情况采用针对性的处理措施如管桩内芯放钢筋笼灌芯加固处理以及承台地梁加强和补桩等。%The prestressed pipe pile has a variety of desired characteristics such as high bearing capacity, low cost and good quality, and has an extensive use in Jiangsu and Zhejiang area. But in the most case of complex ground, especially if it’ s in the soft soil of Ningbo, the concrete pile has the tendency to being deviated, broken and sloped when hammered. Based on an engineering example, the reason of sloping prestressed pipe piles and the treatment measures are given. First of all, the sloping condition of each pile should be made clearly, then the damaged position of each pile is found out using low strain dynamic tests, and finally treatment measures are put forward, such as placing reinforcement cage and pouring concrete in the cores of piles, strengthening through cushion caps and grade beams and adding bored piles.

  4. Pile Foundation Mechanical Characteristic Analysis for Three Types of Wellhead Platforms in East China Sea%东海三种井口平台桩基受力特性分析

    Institute of Scientific and Technical Information of China (English)

    孙友义; 侯金林; 刘明

    2014-01-01

    Wellhead platforms with 4 legs and 8 skirt piles can be classified as three forms inclu-ding single-batter type,double-batter type and batter-to-vertical type according to the jacket leg batter.The pile foundation mechanical characteristic is an important performance of the platform. Pile foundation mechanical characteristics for the three types of platforms were studied,using SACS software,based on nonlinear soil-pile-structure interaction analysis.Influence factor analy-sis on pile foundation mechanical characteristics was performed,and measures for improving the pile foundation bearing capacities were discussed.The results can provide a reference for jacket and pile foundation design for these types of platforms.%4腿8裙桩井口平台按导管架腿斜度可分为单斜式、双斜式与斜变直式3种形式。桩基受力特性是平台的重要性能。以 SACS 程序为分析工具,基于非线性土壤/桩基/结构交互分析,研究了这3种形式平台的桩基受力特性。通过桩基受力影响因素分析,提出了改善桩基受力的措施,可为该类平台的导管架与桩基设计提供参考。

  5. Studying and Preparing of Basic Time for Piling Works by Synthetic Equations

    OpenAIRE

    Naiyakeat Pongpatanasuegsa; Wisoot Jiradamkerng; Supa Thongmai

    2011-01-01

    The objective of this research is to study and prepare basic time for piling works by synthetic equations. The time data of 7 work elements of piling works were collected from 10 different construction sites in Phuket Province of Thailand. The synthetic equations were derived with multiple regressions analysis method using statistic software package. These work elements consisted of pile driving work , moving piling rig left or right on supporting rails , moving supporting rails left or right...

  6. The tensile capacity of steel pipe piles drilled into the bedrock

    OpenAIRE

    Sirén, Rosa

    2015-01-01

    This Master’s thesis focuses on drilled pipe piles and their ability to transfer tensile forces. The tensile forces affecting pile foundations are usually transferred to the bedrock by rock anchors. If drilled pipe piles could transfer some of these tension forces, foundation work would be faster, easier and more cost-effective. This thesis is a continuation of a study published in 2014, which also investigated the tensile capacity of drilled pipe piles. This thesis consists of two main ...

  7. Comparative Model Tests of SDP and CFA Pile Groups in Non-Cohesive Soil

    OpenAIRE

    Krasiński Adam; Kusio Tomasz

    2015-01-01

    The research topic relates to the subject of deep foundations supported on continuous flight auger (CFA) piles and screw displacement piles (SDP). The authors have decided to conduct model tests of foundations supported on the group of piles mentioned above and also the tests of the same piles working as a single. The tests are ongoing in Geotechnical Laboratory of Gdaňsk University of Technology. The description of test procedure, interpretation and analysis of the preliminary testing series...

  8. Dynamic Active Earth Pressures of the Retaining Piles with Anchors under Vehicle Loads

    OpenAIRE

    Hong-zhi Qiu; Ji-ming Kong; Ren-chao Wang

    2016-01-01

    The pile-anchor supporting structure is widely used in foundation pit engineering; then knowledge of active earth pressure on piles is very important for engineers. In this paper, based on the pseudodynamic method and considering the vehicle’s vibration characteristic, a method to calculate the earth pressure on piles under vehicle load is presented. At the same time, the constraint of anchor is simplified relation of lateral deformation of piles in present method. Effects of a wide range of ...

  9. 双向水泥搅拌桩施工工艺及加固效果检测%Construction Technology of Bidirectional Cement Mixing Pile and Detection of Reinforcement Effect

    Institute of Scientific and Technical Information of China (English)

    李晓鹏

    2016-01-01

    According to the southwest of Taiyuan railway engineering examples,the soft soil founda-tion treatment construction using the bidirectional cement mixing pile construction technology princi-ple,construction technology is introduced.The use of coring method analysis to determine the cement mixing pile quality,and using the load test analysis to determine the process and method of force bear-ing capacity of single pile composite foundation are illustrated.The results show that the effect is good,the strength and bearing capacity of the pile are obviously improved,and the settlement of foundation is controlled by the two way cement mixing piles.%结合太原西南环铁路工程实例应用,介绍软土地基处理施工采用的双向水泥搅拌桩技术施工原理、施工工艺,并说明利用钻心法分析确定水泥搅拌桩桩身质量,利用载荷试验分析确定单桩复合地基承载力的过程与方法。实例表明,采用双向水泥搅拌桩加固软土地基,效果良好,桩体强度及地基承载能力均明显提高,地基沉降得到控制。

  10. Bearing fatigue investigation 3

    Science.gov (United States)

    Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

    1982-01-01

    The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

  11. EcoBears

    DEFF Research Database (Denmark)

    Nielsen, Nick; Pedersen, Sandra Bleuenn; Sørensen, Jens Ager;

    2015-01-01

    In this paper, we introduce the EcoBears concept that aims to augment household appliances with functional and aesthetic features to promote their "use'' and "longevity of use'' to prevent their disposal. The EcoBears also aim to support the communication of environmental issues in the home setti...

  12. 单桩承载力预测的PSO-Gompertz模型研究%The PSO-Gompertz Model Study for Single Pile Capacity Prediction

    Institute of Scientific and Technical Information of China (English)

    杜勇立

    2012-01-01

    在对桩的荷载传递规律进行分析的基础上,运用生物生长观点将Gompertz函数模型用于单桩极限荷载的预测中,给出模型参数估计的粒子群(PSO)方法,并在实例分析的基础上将PSO-Gompertz模型与常用预测模型进行了对比.结果表明:在桩顶静荷载作用下,单桩承载力的发展经历了发生、发展、成熟并趋于饱和的生长过程;桩的荷载Q-沉降s曲线可用logistic函数描述;提出的PSO-Gompertz模型比双曲线模型、指数模型有更高的预测精度.%According to the biological growth law, the Gompertz function model was used to the forecast of single-pile ultimate load after the load transmission mechanism of piles was analyzed, the Particle Swarm Optimization for parameter estimation of the model was provided, the prediction effects of PSO-Gompertz model and double common forecast models were compared with each other based on case-study. The results show that the growth process of pile bearing capacity usually experience the stages of begin, development, maturity and saturation; the load-settlement (Q-s) curve of piles under static load can be described by the Gompertz function; PSO-Gompertz model works better than the hyperbola and index ones in the forecast of single-pile ultimate load.

  13. Design and Construction of the Pile Foundation of Yantian Port 2nd-Phase Container Terminal%盐田港二期工程集装箱码头桩基设计与施工

    Institute of Scientific and Technical Information of China (English)

    顾寄平

    2000-01-01

    It introduces the calculation principle for the structures of three 50, 000 dwtcontainer terminals of Yantian Port 2nd-phase Project, types of foundation piles and the structural types, piling control standard, as well as the construction machinery and construction method for embedded piles, anchor piles and embedded-anchor piles. It also gives an introduction to the actural bearing capacity testing by combining high-strain dynamic test with static load test.%介绍盐田港二期3个5万吨级集装箱码头结构的计算原则,基桩类型及其结构型式,沉桩控制标准及嵌岩桩、锚定桩、锚定嵌桩的施工机具和施工方法,还介绍了采用高应变动力试验与静载试验相结合的方法验证工程桩实际承载力的情况。

  14. Arcturus and the Bears

    Science.gov (United States)

    Antonello, E.

    2009-08-01

    Arcturus is the brightest star in Bootes. The ancient Greek name Arktouros means Bear Guard. The star, however, is not close to Ursa Maior (Big She-Bear) and Ursa Minor (Little She-Bear), as the name would suggest. This curious discrepancy could be explained by the star proper motion, assuming the name Bear Guard is a remote cultural heritage. The proper motion analysis could allow us to get an insight also into an ancient myth regarding Ursa Maior. Though we cannot explain scientifically such a myth, some interesting suggestions can be obtained about its possible origin, in the context of the present knowledge of the importance of the cult of the bear both during the Palaeolithic times and for several primitive populations of modern times, as shown by the ethnological studies.

  15. Experimental assessment of the insertion loss of an underwater noise mitigation screen for marine pile driving

    NARCIS (Netherlands)

    Jansen, H.W.; Jong, C.A.F. de; Jung, B.

    2012-01-01

    Because of the concern about potential effects on marine pile driving, the industry is developing silent marine pile driving concepts. One of the new concepts, which has been engineered by IHC Hydrohammer in the Netherlands, is the application of a steel Noise Mitigation Screen (NMS) around the pile

  16. The Underwater Sound Field from Impact Pile Driving and Its Potential Effects on Marine Life

    NARCIS (Netherlands)

    Dahl, P.H.; Jong, C.A.F. de; Popper, A.N.

    2015-01-01

    Impact pile driving is a method used to install piles for marine and inland water construction projects using high-energy impact hammers. The installation of hollow steel piles in this manner can produce extremely high sound levels in the surrounding waters (as well as in the air). Given the large-

  17. New method of designing anti-slide piles-the strength reduction FEM

    Institute of Scientific and Technical Information of China (English)

    Zheng Yingren; Zhao Shangyi; Lei Wenjie; Tang Xiaosong

    2010-01-01

    At present,the thrust of an anti-slide pile can be worked out with some calculation methods.However,the resistance in front of the pile,the distributions of resistance and thrust,and appropriate pile length cannot be easily obtained.In this paper,the authors applied the strength-reduction finite element method(FEM)to several design cases of anti-slide piles.Using this method,it is possible to take the pile-soil interactions into consideration,obtain reasonable resistance in front of pile and the distributions of thrust and resistance,and reasonable lengths of anti-slide piles.In particular,the thrust and resistance imposed on embedded anti-slide piles can be calculated and composite anti-slide pile structures such as anchored piles and braced piles can be optimized.It is proved through the calculation examples that this method is more reliable and economical in the design of anti-slide pile.

  18. Centrifuge modeling of rapid load tests with open-ended piles

    NARCIS (Netherlands)

    Nguyen, T.C.; Van Lottum, H.; Holscher, P.; Van Tol, A.F.

    2012-01-01

    Rapid and static load tests were conducted on open-ended and close-ended piles in the Deltares GeoCentriflige. hi flight, a pile was driven into the soil. Both fme-grained sand and silt beds were tested. Both the rapid and static soil resistances o f a close-ended pile were higher than the soil resi

  19. Bending behavior of double-row stabilizing piles with constructional time delay

    Institute of Scientific and Technical Information of China (English)

    Yang YU; Yue-quan SHANG; Hong-yue SUN

    2012-01-01

    The bending behavior of double-row stabilizing plies is associated with the constructional time delay (CTD),which can be defined as the time interval between the installations of the front stabilizing pile and the rear stabilizing pile.This paper investigates the effect of CTD on the bending moments of double-row stabilizing piles and a method for determining the optimal CTD is proposed.The stabilizing pile is modeled as a cantilever pile embedded in the Winkler elastic foundation.A triangular distributed earth pressure is assumed on the pile segment in the sliding layer.The front stabilizing pile and the rear stabilizing pile are connected by a beam with pinned joints.The analytical solutions of bending moments on the front and the rear stabilizing piles are derived and the accuracy of bending moment solutions is validated by comparing the tensile strain measured from the Hongyan landslide project,Taizhou,Zhejiang,China.It is concluded that CTD has a significant influence on the bending moments of double-row stabilizing piles.An optimal CTD can be obtained when the maximum tensile stress in the front stabilizing pile is equal to that in the rear stabilizing pile,which is 1.4 months for the Hongyan landslide project.

  20. 30 CFR 56.16002 - Bins, hoppers, silos, tanks, and surge piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Bins, hoppers, silos, tanks, and surge piles... MINES Materials Storage and Handling § 56.16002 Bins, hoppers, silos, tanks, and surge piles. (a) Bins, hoppers, silos, tanks, and surge piles, where loose unconsolidated materials are stored, handled...

  1. Response of single piles and pipelines in liquefaction-induced lateral spreads using controlled blasting

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Two full-scale experiments using controlled blasting were conducted in the Port of Tokachi on Hokkaido Island,Japan, to assess the behavior of piles and pipelines subjected to lateral spreading. Test specimens were extensively instrumented with strain gauges to measure the distribution of moment during lateral spreading. This allowed us to compute the loading condition, as well as to conduct damage and performance assessments on the piles and pipelines. This paper presents the test results and discussions on the response of single piles and pipelines observed from the full-scale experiments. Based on the test results, it can be concluded that using controlled blasting successfully liquefied the soil, and subsequently induced lateral spreading. The movements of the single pile, as well as the transverse pipelines, were approximately the same as the free field soil movement. Observed moment distribution of the single pile indicated that global translation of the liquefied soil layer provided insignificant force to the pile. In addition, the degree of fixity at the pile tip significantly affected the moment along the pile as well as the pile head displacement. The pile with a higher degree of fixity at the pile tip had smaller pile head displacement but larger maximum moment.

  2. 30 CFR 57.16002 - Bins, hoppers, silos, tanks, and surge piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Bins, hoppers, silos, tanks, and surge piles... NONMETAL MINES Materials Storage and Handling § 57.16002 Bins, hoppers, silos, tanks, and surge piles. (a) Bins, hoppers, silos, tanks, and surge piles, where loose unconsolidated materials are stored,...

  3. 上海中心大厦桩基础变刚度调平设计%Variable rigidity design in the pile foundation of Shanghai Tower

    Institute of Scientific and Technical Information of China (English)

    姜文辉; 巢斯

    2012-01-01

    How to control the settlement and differential settlements of buildings in Shanghai is important. Variable rigidity design is based on the settlement control and is efficient in differential-settlement control of high-rise buildings with piles group and soft bed. Large-diameter post-grouting bored piles are adopted in the foundation of Shanghai Tower. The foundation of Shanghai Tower was designed according to the variable rigidity conception. By selecting length and distance of piles properly, the differential settlements of plate at centre and edges were controlled within the reasonable range, which can optimize the plate design. Pile tests show that post-grouting technique can increase the bearing capacity of the single pile as well as decrease differences among bearing capacities of different piles.%对于上海地区的超厚软弱土层,如何控制建筑沉降和差异沉降是设计的重点。变刚度调平设计是基于沉降控制的基础设计方法,对于群桩基础和软土地基的高层建筑沉降差异控制有显著的效果。介绍了上海中心大厦大直径后注浆钻孔灌注桩基础设计中按照变刚度调平概念,通过合理选择桩长和桩距,使得主楼底板中心和边缘的计算差异沉降控制在合理的范围,优化了底板的设计。经过试桩,认为后注浆的桩端注浆方法能有效提高单桩承载力和减小不同桩承载力间的变异值。

  4. 有斜桩和无斜桩高桩码头地震反应的非线性有限元分析%Nonlinear finite element analysis for seismic performance of wharf structures with and without batter piles attached

    Institute of Scientific and Technical Information of China (English)

    李颖; 贡金鑫

    2011-01-01

    为清楚了解斜桩在地震中的性能,采用非线性有限元软件ABAQUS对全直桩码头和斜桩码头分别进行了弹塑性时程分析.全直桩码头为全部采用直桩的码头,有斜桩码头分2种情况,一种是1根直桩顶部另设置1对斜桩,其余直桩全部与全直桩码头相同,另一种是将直桩截面尺寸和配筋减小后设置1对斜桩使其荷载-变形特性与全直桩码头相近.研究表明,有斜桩码头的刚度较大,水平位移、直桩桩端弯矩和水平力均较小,但残余位移较大.当地震作用较强时,由于斜桩变形能力较差,混凝土容易压碎,丧失水平承载力.计算分析也同时表明,近陆侧直桩比斜桩承受更大的地震弯矩和水平侧向力.%Recent experiences have demonstrated that earthquake-induced damage to wharf structure is highly susceptible to batter piles. In the United States, wharf structures without batter piles attached are commonly constructed in seismically active regions, however, batter piles are still being advocated in new wharf designs in China. In order to better understand seismic performance of batter piles, elastic-plastic time history analysis is implemented for two cases using ABAQUS. The first case analysis is carried out with and without the batter piles attached at identical input accelerations. The second case focuses on the wharf which has a similar load-displacement curve with vertical pile-supported structure. The evaluation of model behavior is summarized: ( 1 )batter piles attract less lateral load and moment than surrounding vertical piles; (2)horizontal displacements increase where batter piles are detached due to less stiffness; (3)significant increases in residual displacement are observed when the batter piles are attached; (4) the deformability of batter piles is weak, resulting in concrete cracks and bearing capacity loss; (5) the onshore vertical pile attracts more load than the offshore vertical pile which has a greater

  5. Study of deformation characteristics of overlength large diameter piles%超长大直径桩的变形特性研究

    Institute of Scientific and Technical Information of China (English)

    黄生根; 彭从文

    2009-01-01

    应用有限元方法,分析了不同几何参数情况下超长大直径桩的荷载-沉降关系、桩顶沉降量的构成及其比例.根据计算结果得出以下规律:超长桩极限承载力的发挥需要较大的桩顶位移,且随着长径比的增大而增大;超长桩的变形主要由桩身压缩量控制,桩端沉降所占比例较小,且各沉降分项所占比例与长径比存在明显的函数关系;对长径比为50~83的超长大直径桩,极限状态下的桩身压缩量所占比例为65.2 %~71.83 %,桩端荷载所引起的沉降量所占比例为15.7 %~9.72 %;工作荷载作用下的桩身压缩量所占比例为66.1 %~72.5 %,桩端荷载所引起的沉降量所占比例为10.8 %~3.9 %.%The load-settlement relationship, the composition and ratios of pile head settlement of overlength large diameter piles are analyzed with FEM in different situations of geometric parameters. The following rules are obtained according to the calculated results: the big settlements are needed to bring the ultimate bearing capacities of overlength large diameter piles into play; and the required settlements increase with increase of length-diameter ratios (L/D). The deformation of over-length large diameter piles are mainly controlled by the compression deformation of pile shafts; the proportion of pile tip settlement is low; and there is a function relation between the proportion of each composition of settlement and length-diameter ratio. For the over-length large diameter piles with L/D=50-83, the proportions of compression deformation of pile shafts are 65.2 %-71.83 % in the ultimate states; and the proportions of settlements caused by the pile end loads are 15.7 %-9.72 %; under the working load states, the proportions of compression deformation of pile shafts are 66.1 %-72.5 %; and the proportions of settlements caused by the pile end loads are 10.8 %-3.9 %.

  6. Numerical investigation of piled raft foundation in mitigating embankment vibrations induced by high-speed trains

    Institute of Scientific and Technical Information of China (English)

    付强; 刘汉龙; 丁选明; 郑长杰

    2015-01-01

    A three-dimensional dynamic finite element model of track-ballast-embankment and piled raft foundation system is established. Dynamic response of a railway embankment to a high-speed train is simulated for two cases: soft ground improved by piled raft foundation, and untreated soft ground. The obtained results are compared both in time domain and frequency domain to evaluate the effectiveness of the ground improvement in mitigating the embankment vibrations induced by high-speed trains. The results show that ground improving methods can significantly reduce the embankment vibrations at all considered train speeds(36-432 km/h). The ground response to a moving load is dictated largely by the relationship between load speed and characteristic value of wave velocities of the ground medium. At low speeds, the ground response from a moving load is essentially quasi-static. That is, the displacements fields are essential the static fields under the load simply moving with it. For the soft ground, the displacement on the ballast surface is large at all observed train speeds. For the model case where the ground is improved by piled raft foundation, the peak displacement is reduced at all considered train speeds compared with the case without ground improvement. Based on the effect of energy-dissipating of ballast-embankment-ground system with damping, the train-induced vibration waves moving in ballast and embankment are trapped and dissipated, and thus the vibration amplitudes of dynamic displacement outside the embankment are significantly reduced. But for the vibration amplitude of dynamic velocity, the vibration waves in embankment are absorbed or reflected back, and the velocity amplitudes at the ballast and embankment surface are enhanced. For the change of the vibration character of embankment and ballast, the bearing capacity and dynamic character are improved. Therefore, both of the static and dynamic displacements are reduced by ground improvement; the dynamic

  7. Numerical investigation of piled raft foundation in mitigating embankment vibrations induced by high-speed trains

    Institute of Scientific and Technical Information of China (English)

    付强; 刘汉龙; 丁选明; 郑长杰

    2015-01-01

    A three-dimensional dynamic finite element model of track-ballast-embankment and piled raft foundation system is established. Dynamic response of a railway embankment to a high-speed train is simulated for two cases: soft ground improved by piled raft foundation, and untreated soft ground. The obtained results are compared both in time domain and frequency domain to evaluate the effectiveness of the ground improvement in mitigating the embankment vibrations induced by high-speed trains. The results show that ground improving methods can significantly reduce the embankment vibrations at all considered train speeds (36− 432 km/h). The ground response to a moving load is dictated largely by the relationship between load speed and characteristic value of wave velocities of the ground medium. At low speeds, the ground response from a moving load is essentially quasi-static. That is, the displacements fields are essential the static fields under the load simply moving with it. For the soft ground, the displacement on the ballast surface is large at all observed train speeds. For the model case where the ground is improved by piled raft foundation, the peak displacement is reduced at all considered train speeds compared with the case without ground improvement. Based on the effect of energy-dissipating of ballast-embankment-ground system with damping, the train-induced vibration waves moving in ballast and embankment are trapped and dissipated, and thus the vibration amplitudes of dynamic displacement outside the embankment are significantly reduced. But for the vibration amplitude of dynamic velocity, the vibration waves in embankment are absorbed or reflected back, and the velocity amplitudes at the ballast and embankment surface are enhanced. For the change of the vibration character of embankment and ballast, the bearing capacity and dynamic character are improved. Therefore, both of the static and dynamic displacements are reduced by ground improvement; the dynamic

  8. 20051655 - Petronas, Capacity of Driven Piles Offshore Malaysia

    DEFF Research Database (Denmark)

    Augustesen, Anders

    This document is one of four notes concerning the effects of time (in this case ageing) on the vertical capacity of piles. It includes summaries of relevant publications related to the topic. Further, focus has been paid to publications that deal with quantification of setup and not the mechanism...

  9. 20051655 - Petronas, Capacity of Driven Piles Offshore Malaysia

    DEFF Research Database (Denmark)

    Augustesen, Anders

    This report presents the results of work carried out by Aalborg Univesity for NGI related to the effects of ageing on the axial capacity of piles in clay and sand. The document is the fourth of four notes regarding the subject and it includes a recommended approach to account for ageing effects f...

  10. Airborne sound propagation over sea during offshore wind farm piling.

    Science.gov (United States)

    Van Renterghem, T; Botteldooren, D; Dekoninck, L

    2014-02-01

    Offshore piling for wind farm construction has attracted a lot of attention in recent years due to the extremely high noise emission levels associated with such operations. While underwater noise levels were shown to be harmful for the marine biology, the propagation of airborne piling noise over sea has not been studied in detail before. In this study, detailed numerical calculations have been performed with the Green's Function Parabolic Equation (GFPE) method to estimate noise levels up to a distance of 10 km. Measured noise emission levels during piling of pinpiles for a jacket-foundation wind turbine were assessed and used together with combinations of the sea surface state and idealized vertical sound speed profiles (downwind sound propagation). Effective impedances were found and used to represent non-flat sea surfaces at low-wind sea states 2, 3, and 4. Calculations show that scattering by a rough sea surface, which decreases sound pressure levels, exceeds refractive effects, which increase sound pressure levels under downwind conditions. This suggests that the presence of wind, even when blowing downwind to potential receivers, is beneficial to increase the attenuation of piling sound over the sea. A fully flat sea surface therefore represents a worst-case scenario. PMID:25234870

  11. Enhanced In-pile Instrumentation for Material Testing Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Joy Rempe; Darrell Knudson; Joshua Daw; Troy Unruh; Benjamin Chase; Kurt Davis; Robert Schley

    2012-07-01

    An increasing number of U.S. nuclear research programs are requesting enhanced in-pile instrumentation capable of providing real-time measurements of key parameters during irradiations. For example, fuel research and development funded by the U.S. Department of Energy now emphasize approaches that rely on first principle models to develop optimized fuel designs that offer significant improvements over current fuels. To facilitate this approach, high fidelity, real-time data are essential for characterizing the performance of new fuels during irradiation testing. Furthermore, sensors that obtain such data must be miniature, reliable and able to withstand high flux/high temperature conditions. Depending on user requirements, sensors may need to obtain data in inert gas, pressurized water, or liquid metal environments. To address these user needs, in-pile instrumentation development efforts have been initiated as part of the Advanced Test Reactor (ATR) National Scientific User Facility (NSUF), the Fuel Cycle Research & Development (FCR&D), and the Nuclear Energy Enabling Technology (NEET) programs. This paper reports on recent INL achievements to support these programs. Specifically, an overview of the types of sensors currently available to support in-pile irradiations and those sensors currently available to MTR users are identified. In addition, recent results and products available from sensor research and development are detailed. Specifically, progress in deploying enhanced in-pile sensors for detecting elongation and thermal conductivity are reported. Results from research to evaluate the viability of ultrasonic and fiber optic technologies for irradiation testing are also summarized.

  12. Calibration of Partial Factors for Basal Reinforced Piled Embankments

    NARCIS (Netherlands)

    Van Duijnen, P.G.; Schweckendiek, T.; Calle, E.O.F.; Van Eekelen, S.J.M.

    2015-01-01

    In the Netherlands, the design guideline for basal reinforced piled embankments has been revised (CUR226:2015) adopting a new analytical design model (The Concentric Arches (CA) model, Van Eekelen et al., 2013; 2015). The CA model provides geosynthetic reinforcement (GR) strains which were compared

  13. Centrifuge modelling of rigid piles in soft clay

    DEFF Research Database (Denmark)

    Klinkvort, R.T.; Poder, M.; Truong, P.;

    2016-01-01

    of this study is to employ centrifuge modelling in order to derive experimental p-y curves for rigid piles embedded in over-consolidated soft clay. A kaolin clay sample was prepared and pre-consolidated by applying a constant pressure at the soil surface, while different over-consolidation ratios were achieved...

  14. Finite element analysis of soil-sheet pile interaction

    Science.gov (United States)

    Nyby, D. W.

    A finite element model which accurately and economically models soil-sheet pile structures was developed. The model was used to analyze cantilever and anchored sheet pile walls. The finite element model includes transition and interface elements. The transition element has the capability of conforming to the displaced shape of the sheet pile elements on one side (cubic element) and soil elements on the other sides (bilinear element). The interface element models the frictional resistance between the soil and the sheet pile. It behaves elastically below a threshold force level (Coulomb friction) and perfectly plastic above this value. The soil is modeled using nonlinear constitutive relations. These relations are used for both the transition elements and the bilinear elements. The economy of the finite element model was increased in two ways. Closed-form integration was used to reduce the computational effort and an equation solver was used which takes advantage of the banded, symmetric, and positive-definite characteristics of the global stiffness matrix.

  15. Rapid pile load tests in the geotechnical centrifuge

    NARCIS (Netherlands)

    Holscher, P.; Van Tol, A.F.; Huy, N.Q.

    2012-01-01

    Centrifiige experiments were carried out to gain insight into the factors that affect the mobilized resistance during rapid load testing on piles in sand. The influence of generated pore water pressure during rapid load tests is shidied, and its effect on the commonly used unloadmg point method to d

  16. The impact of wind energy turbine piles on ocean dynamics

    Science.gov (United States)

    Grashorn, Sebastian; Stanev, Emil V.

    2016-04-01

    The small- and meso-scale ocean response to wind parks has not been investigated in the southern North Sea until now with the help of high-resolution numerical modelling. Obstacles such as e.g. wind turbine piles may influence the ocean current system and produce turbulent kinetic energy which could affect sediment dynamics in the surrounding area. Two setups of the unstructured-grid model SCHISM (Semi-implicit Cross-scale Hydroscience Integrated System Model) have been developed for an idealized channel including a surface piercing cylindrical obstacle representing the pile and a more realistic test case including four exemplary piles. Experiments using a constant flow around the obstacles and a rotating M2 tidal wave are carried out. The resulting current and turbulence patterns are investigated to estimate the influence of the obstacles on the surrounding ocean dynamics. We demonstrate that using an unstructured ocean model provides the opportunity to embed a high-resolution representation of a wind park turbine pile system into a coarser North Sea setup, which is needed in order to perform a seamless investigation of the resulting geophysical processes.

  17. 29 CFR 1926.603 - Pile driving equipment.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Pile driving equipment. 1926.603 Section 1926.603 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Motor Vehicles, Mechanized Equipment, and...

  18. Vision-based autonomous grasping of unknown piled objects

    International Nuclear Information System (INIS)

    Computer vision techniques have been used to develop a vision-based grasping capability for autonomously picking and placing unknown piled objects. This work is currently being applied to the problem of hazardous waste sorting in support of the Department of Energy's Mixed Waste Operations Program

  19. Dynamic Response of Intact Piles to Impulse Loads

    Science.gov (United States)

    Liao, Shutao T.; Roesset, Jose M.

    1997-04-01

    The objective of this work was to evaluate the theoretical capabilities of the non-destructive impact-response method in estimating the length and cross-sectional area of intact piles. Three-dimensional (3-D) axisymmetric finite element models were developed to simulate the testing. The results obtained were compared to one-dimensional solutions to evaluate the importance of 3-D effects. Extensive parametric studies were then performed on piles without defects. In each parametric study, the results from the direct use of time histories of displacements or velocities, the mobility function and the Fourier transform of the recorded displacements (impact-echo method) were compared in order to assess their relative advantages and disadvantages. The effects of the relative stiffness of the surrounding soil to that of the pile and of the embedment depth were also investigated for all three methods. In a companion paper the use of these procedures to detect defects such as bulbs (increases in the cross-sectional area of the pile) or necks (decreases in area) is studied. Int. J. Numer. Anal. Meth. Geomech., vol. 21, 255-275 (1997)

  20. Numerical experiments with rubble piles : equilibrium shapes and spins

    NARCIS (Netherlands)

    Richardson, Derek C.; Elankumaran, Pradeep; Sanderson, Robyn E.

    2005-01-01

    We present numerical experiments investigating the shape and spin limits of self-gravitating "perfect" rubble piles that consist of identical, smooth, rigid, spherical particles with configurable normal coefficient of restitution and no sliding friction. Such constructs are currently employed in a v

  1. Research on Applicable Mechanism of Pipe Pile in Subgrade Engineering of Passenger Dedicated Line%客运专线路基工程中管桩应用机理研究

    Institute of Scientific and Technical Information of China (English)

    刘永超; 许再良; 张劲松; 王清龙

    2011-01-01

    Research purposes: Pipe pile has been widely applied in construction of passenger dedicated line and highspeed railway.Combining the design, construction and subsidence monitoring of the Beijing - Tianjin Intercity Railway,the applicable mechanism of the pipe pile in the subgrade engineering was systematically studyed for further understanding of the pipe pile's bearing capacity and the roadbed's actual settlement characteristics, and for the study on the pipe pile's shear performance and role in guaranteeing the subgrade stability.Research conclusions: Pipe pile featured with the high strength, short construction period and easy control of construction quality can meet the high demand of construction of passenger dedicated line with less total settlement and less settlement velocity at the different phases compared with other reinforcement methods.In the soil foundation, under the action of horizontal force, pipe pile is in failure state due to the bending moments.The check calculation of the entire stability of the subgrade is made with the shear strength, resulting in high safety coefficient valuations.The load bearing modes of the pipe pile include the modes of pile - raft structure, pile - board structure and pile - net structure.It is proposed to strengthen control of the construction quality, to improve the strength of soil between piles and the pipe pile's top connections and to do the research on pile- beam structure.%研究目的:管桩已广泛应用于客运专线和高速铁路建设工程中,为深入探讨管桩的承载性能和路基实测沉降特性,并研究管桩的抗剪性能及在路基整体稳定中的作用,结合京津城际客运专线的设计、施工和沉降监测,系统地研究管桩在路基工程中的应用机理.研究结论:管桩具有高强、工期快、质量易于控制等优点,可满足客运专线建设标准高的要求,总沉降量和不同阶段的沉降速率明显优于其它加固方式;在水平力作用下土

  2. Effect of sediment on vertical dynamic impedance of rock-socketed pile with large diameter

    Institute of Scientific and Technical Information of China (English)

    俞缙; 蔡燕燕; 吴文兵

    2013-01-01

    Based on the fictitious soil pile model, the effect of sediment on the vertical dynamic impedance of rock-socketed pile with large diameter was theoretically studied by means of Laplace transform technique and impedance function transfer method. Firstly, the sediment under rock-socketed pile was assumed to be fictitious soil pile with the same sectional area. The Rayleigh-Love rode model was used to simulate the rock-socketed pile and the fictitious soil pile with the consideration of the lateral inertial effect of large-diameter pile. The layered surrounding soils and bedrock were modeled by the plane strain model. Then, by virtue of the initial conditions and boundary conditions of the soil pile system, the analytical solution of the vertical dynamic impedance at the head of rock-socketed pile was derived for the arbitrary excitation acting on the pile head. Lastly, based on the presented analytical solution, the effect of sediment properties, bedrock property and lateral inertial effect on the vertical dynamic impedance at rock-socketed pile head were investigated in detail. It is shown that the sediment properties have significant effect on the vertical dynamic impedance at the rock-socketed pile head. The ability of soil-pile system to resist dynamic vertical deformation is weakened with the increase of sediment thickness, but amplified with the increase of shear wave velocity of sediment. The ability of soil pile system to resist dynamic vertical deformation is amplified with the bedrock property improving, but the ability of soil-pile system to resist vertical vibration is weakened with the improvement of bedrock property.

  3. Behavior of Pile Group with Elevated Cap Subjected to Cyclic Lateral Loads

    Institute of Scientific and Technical Information of China (English)

    陈云敏; 顾明; 陈仁朋; 孔令刚; 张浙杭; 边学成

    2015-01-01

    The pile group with elevated cap is widely used as foundation of offshore structures such as turbines, power transmission towers and bridge piers, and understanding its behavior under cyclic lateral loads induced by waves, tide water and winds, is of great importance to designing. A large-scale model test on 3×3 pile group with elevated cap subjected to cyclic lateral loads was performed in saturated silts. The preparation and implementation of the test is presented. Steel pipes with the outer diameter of 114 mm, thickness of 4.5 mm, and length of 6 m were employed as model piles. The pile group was cyclic loaded in a multi-stage sequence with the lateral displacement controlled. In addition, a single pile test was also conducted at the same site for comparison. The displacement of the pile cap, the internal forces of individual piles, and the horizontal stiffness of the pile group are presented and discussed in detail. The results indicate that the lateral cyclic loads have a greater impact on pile group than that on a single pile, and give rise to the significant plastic strain in the soil around piles. The lateral loads carried by each row of piles within the group would be redistributed with loading cycles. The lateral stiffness of the pile group decreases gradually with cycles and broadly presents three different degradation patterns in the test. Significant axial forces were measured out in some piles within the group, owing to the strong restraint provided by the cap, and finally lead to a large settlement of the pile group. These findings can be referred for foundation designing of offshore structures.

  4. Ultra-precision bearings

    CERN Document Server

    Wardle, F

    2015-01-01

    Ultra-precision bearings can achieve extreme accuracy of rotation, making them ideal for use in numerous applications across a variety of fields, including hard disk drives, roundness measuring machines and optical scanners. Ultraprecision Bearings provides a detailed review of the different types of bearing and their properties, as well as an analysis of the factors that influence motion error, stiffness and damping. Following an introduction to basic principles of motion error, each chapter of the book is then devoted to the basic principles and properties of a specific type of bearin

  5. The thermal behaviour of three different auger pressure grouted piles used as heat exchangers

    OpenAIRE

    Loveridge, F.; Olgun, C.G.; Brettmann, T.; Powrie, W.

    2014-01-01

    Three auger pressure grouted (APG) test piles were constructed at a site in Richmond, Texas. The piles were each equipped with two U-loops of heat transfer pipes so that they could function as pile heat exchangers. The piles were of two different diameters and used two different grouts, a standard APG grout and a thermally enhanced grout. Thermal response tests, where fluid heated at a constant rate is circulated through the pipe loops, were carried out on the three piles, utilising either ...

  6. Experimental analysis of the inertial soil-pile interaction in the centrifuge

    OpenAIRE

    CHENAF, N; CHAZELAS, JL; Escoffier, S.

    2006-01-01

    The soil-pile dynamic interaction is studied through centrifuge tests. In this paper, we focus on the inertial effect as a first step to knowledge the seismic behaviour of the soil-pile system. A single shock test, applied at the head of a flexible single pile, is used to simulate an impact on bridge piers ; successive shocks are also used to simulate boat impacts on harbour facilities. To improve the understanding of the inertial soil-pile interaction, a comparison of pile response to both l...

  7. Finite Element Investigations on the Interaction between a Pile and Swelling Clay

    OpenAIRE

    Kaufmann, Kristine Lee; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    2010-01-01

    This paper aims to investigate the interaction between a pile and a swelling soil modelled as a cohesive soil subjected to unloading. The investigations include analyses of the heave of the excavation level, shear stresses at the soil–pile interface and internal pile forces based on a case study of Little Belt Clay. The case study involves a circular concrete pile installed in clay immediately after an excavation. The influence of the swelling soil on the soil–pile interaction and the interna...

  8. Field monitoring of static, dynamic, and statnamic pile loading tests using fibre Bragg grating strain sensors

    Science.gov (United States)

    Li, Jin; Correia, Ricardo P.; Chehura, Edmon; Staines, Stephen; James, Stephen W.; Tatam, Ralph; Butcher, Antony P.; Fuentes, Raul

    2009-10-01

    Pile loading test plays an important role in the field of piling engineering. In order to gain further insight into the load transfer mechanism, strain gauges are often used to measure local strains along the piles. This paper reports a case whereby FBG strain sensors was employed in a field trial conducted on three different types of pile loading tests in a glacial till. The instrumentation systems were configured to suit the specific characteristic of each type of test. Typical test results are presented. The great potential of using FBG sensors for pile testing is shown.

  9. Experimental Research on Large Diameter Cast-in-Place Piles Embedded in Rock

    Institute of Scientific and Technical Information of China (English)

    衡朝阳; 何满潮; 姚爱军

    2001-01-01

    This paper expatiated the field test of large diameter cast-in-place piles embedded in soft rock, including static loading test, high or low strain dynamic test, measurement of stresses and strains of pile body, and pressure measurements between pile tip and soft rock. The relative in-situ test problems are discussed. Based on the limit equilibrium theory and the load transfer equation, a synthesis method of analyzing the ultimate carrying capacity of single large diameter pile is put forward. The research results show that the key to determining the ultimate carrying capacity of single pile with a large diameter is the analysis of the intensity of soft rock.

  10. An Experimental Study on Pile Spacing Effects under Lateral Loading in Sand

    Directory of Open Access Journals (Sweden)

    Mahdy Khari

    2013-01-01

    Full Text Available Grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. Ultimate lateral resistance and lateral subgrade modulus within a pile group are known as the key parameters in the soil-pile interaction phenomenon. In this study, a series of experimental investigation was carried out on single and group pile subjected to monotonic lateral loadings. Experimental investigations were conducted on twelve model pile groups of configurations 1 × 2, 1 × 3, 2 × 2, 3 × 3, and 3 × 2 for embedded length-to-diameter ratio l/d = 32 into loose and dense sand, spacing from 3 to 6 pile diameter, in parallel and series arrangement. The tests were performed in dry sand from Johor Bahru, Malaysia. To reconstruct the sand samples, the new designed apparatus, Mobile Pluviator, was adopted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. An increasing of the number of piles in-group decreases the group efficiency owing to the increasing of overlapped stress zones and active wedges. A ratio of s/d more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.

  11. Management recommendations: Bear River

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a review of land management practices at the Bear River Migratory Bird Refuge, by a land use specialist. Recommendations, time frame and additional...

  12. Investigation of Pile- Soil Interaction Subjected to Lateral Loads in Layered Soils

    Directory of Open Access Journals (Sweden)

    A. Avaei

    2008-01-01

    Full Text Available To stabilize infrastructures such as tall buildings, bridges, etc., piles are used to resist lateral loads created from earth pressure, wind, waves and earthquake extensively. Pile design requires understanding of how the load is transferred from a pile to surrounding soil and vice versa. Pile properties, soil stress-strain behavior and pile-soil interaction play important roles in pile-response subjected to lateral loads. A study was carried out to investigate the effects of above-mentioned parameters on pile-soil behavior subjected to lateral forces. A comparison was made between the results derived from finite difference and equivalent spring methods by writing a computer program and using a civil engineering package, respectively.

  13. Small-Scale Testing of Laterally Loaded Non-Slender Piles in a Pressure Tank

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo

    2012-01-01

    The monopile foundation concept is often employed as the foundation for offshore wind turbines. Typically, piles with diameters of 4-6 m and embedded lengths of 15-30 m are em¬ployed. Hence, the length to diameter ratio is around 5. The design method recommended by the American Petroleum Institute...... and Det Norske Veritas is, however, based on slender piles with length to diameter ratios larger than 10. Hence, the design method needs to be validated for non-slender piles. The aim of the present work is to investigate the pile behaviour for non-slender piles by means of small-scale testing. When...... were conducted on six piles with diameters between 40 and 100 mm and length to diameter ratios of 3-6 m. The effect of applying an overburden pressure is eval¬uated for the load-displacement relationships and the variation of pile deflection with depth....

  14. Case Study of CPT-based Design Methods for Axial Capacity of Driven Piles in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard

    2012-01-01

    Today the design of onshore axially loaded driven piles in cohesionless soil is commonly made on basis of CPT-based methods because field investigations have shown strong correlation between the local shaft friction and the CPT cone resistance. However, the recommended design method for axially...... loaded offshore driven piles in cohesionless soil has until now been the β-method given in API. The API-method is based on the effective overburden pressure at the depth in question. Previous studies show deviations between full-scale load test measurements of the axial pile capacity and the predictions...... found by means of the API-method. Compared to the test measurements, the API-method under-estimates the capacity of short piles (piles in loose sand, and gives a shaft capacity less conservative for piles in tension than for piles in compression...

  15. Nonlinear analysis of pile load-settlement behavior in layered soil

    Institute of Scientific and Technical Information of China (English)

    吕述晖; 王奎华; 张鹏; C. J. LEO3

    2015-01-01

    A simplified approach is presented to analyze the single pile settlement in multilayered soil. First, a fictitious soil−pile model is employed to consider the effect of layered soil beneath pile toe on pile settlement behavior. Two approximation methods are proposed to simplify the nonlinear load transfer function and simulate the nonlinear compression of fictitious soil−pile, respectively. On this basis, an efficient program is developed. The procedures for determining the main parameters of mathematical model are discussed. Comparisons with two well-documented field experimental pile loading tests are conducted to verify the rationality of the present method. Further studies are also made to evaluate the practicability of the proposed approach when a soft substratum exists, and the results suggest that the proposed method can provide a constructive means for assessing the settlement of a single pile for use in engineering design.

  16. Bending Moment Calculations for Piles Based on the Finite Element Method

    Directory of Open Access Journals (Sweden)

    Yu-xin Jie

    2013-01-01

    Full Text Available Using the finite element analysis program ABAQUS, a series of calculations on a cantilever beam, pile, and sheet pile wall were made to investigate the bending moment computational methods. The analyses demonstrated that the shear locking is not significant for the passive pile embedded in soil. Therefore, higher-order elements are not always necessary in the computation. The number of grids across the pile section is important for bending moment calculated with stress and less significant for that calculated with displacement. Although computing bending moment with displacement requires fewer grid numbers across the pile section, it sometimes results in variation of the results. For displacement calculation, a pile row can be suitably represented by an equivalent sheet pile wall, whereas the resulting bending moments may be different. Calculated results of bending moment may differ greatly with different grid partitions and computational methods. Therefore, a comparison of results is necessary when performing the analysis.

  17. Rolling bearing analysis

    CERN Document Server

    Harris, Tedric A

    2001-01-01

    One of the most well-known experts in the field brings cutting-edge research to practitioners in the new edition of this important reference. Covers the improved mathematical calculations for rolling bearing endurance developed by the American Society of Mechanical Engineers and the Society of Lubrication and Tribology Engineers. Updated with new material on Condition-Based Maintenance, new testing methods, and new bearing materials.

  18. Gear bearing drive

    Science.gov (United States)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  19. My Little Teddy Bear

    Institute of Scientific and Technical Information of China (English)

    钱佳楠

    2005-01-01

    @@ As Valentine's Day came closer,every shop was full of colourful gifts such as cookies in the shape of heart, chocolates,Teddy Bears and so on.When I step into a shop on February 14th,I felt most lonely as I was alone.With mv eves fixed on a lovely Teddy Bear, I wished that someone could send me this stuffed toy.

  20. 砂石桩与素混凝土桩复合地基桩处理软弱吹填土地基%Treatment on Soft Dredger Fill Foundation for Composite Foundation Between Gravel Pile and Plain Concrete Pile

    Institute of Scientific and Technical Information of China (English)

    焦占生; 雷洋

    2014-01-01

    Taking a project in Caofeidian manufacturing district as an example, the difficulties of soft ground treatment for blowing and filling, the complex use of gravel pile and plain concrete pile are analyzed in this thesis. Not only can it improve the bearing capacity, but also eliminate liquefaction. It is very economical and applicable.%以曹妃甸工业区某项目为例,分析了吹填土软弱地基处理的难点,提出砂石桩与素混凝土桩复合使用,不仅提高承载力,消除液化,又经济适用。

  1. Test study of performance of composite pile foundation of high-speed railway controlling settlement%高速铁路沉降控制复合桩基的性状试验研究

    Institute of Scientific and Technical Information of China (English)

    徐林荣; 王宏贵; 左珅; 刘维正

    2012-01-01

    基于沉降控制设计理念,无砟轨道京沪高速铁路地基处理采用筏板+垫层+疏桩的方法,形成复合桩基以实现有效减少工后沉降和充分利用地基承载力的优化加固方案.为探索该新方法沉降控制机制,选用CFG桩开展了复合桩基现场试验研究,对复合桩基在高速铁路路基填筑、静置、预压卸载过程中的地基沉降变形、桩和桩间土土压力、筏板顶与底部压力进行了长期观测,分析了路基沉降变形、桩-土应力比和荷载分担比以及筏板的受力随填筑高度和固结时间的变化规律.研究表明:筏板+垫层+疏桩联合加固地基方案在初期充分发挥了桩间土承载作用,导致桩与桩间土产生差异沉降;随着垫层的调节作用,筏板可集中发挥桩体的承载能力及显著提高桩顶应力集中程度,地基土沉降主要发生在加固区范围内,从而揭示了复合桩基在路基荷载下的承载机制和变形特性.现场试验结果可为指导高速铁路CFG桩复合桩基设计参数的进一步优化提供试验依据.%Based on the concept of settlement controlling design, the composite piled foundation of raft, cushion and scattered piles has been applied to the ground treatment of Beijing-Shanghai high-speed railway ballast track, in order to achieve the goals of effectively reducing the post-construction settlement and make full use of the natural foundation bearing capacity. The field test of CFG(cement fly-ash gravel) composite piled foundation has been carried out to explore settlement controlling mechanism of the foundation reinforcement technology. Through long-term observation of foundation settlement, the pressure of pile and soil, raft pressure at the top and bottom during the process of high-speed railway filling, standing and preloading and unloading; the variation laws of the embankment settlement, pile-soil stress ratio and load sharing ratio, and the variation of raft pressure with the

  2. Picking up Clues from the Discard Pile (Stereo)

    Science.gov (United States)

    2008-01-01

    As NASA's Phoenix Mars Lander excavates trenches, it also builds piles with most of the material scooped from the holes. The piles, like this one called 'Caterpillar,' provide researchers some information about the soil. On Aug. 24, 2008, during the late afternoon of the 88th Martian day after landing, Phoenix's Surface Stereo Imager took separate exposures through its left eye and right eye that have been combined into this stereo view. The image appears three dimensional when seen through red-blue glasses. This conical pile of soil is about 10 centimeters (4 inches) tall. The sources of material that the robotic arm has dropped onto the Caterpillar pile have included the 'Dodo' and ''Upper Cupboard' trenches and, more recently, the deeper 'Stone Soup' trench. Observations of the pile provide information, such as the slope of the cone and the textures of the soil, that helps scientists understand properties of material excavated from the trenches. For the Stone Soup trench in particular, which is about 18 centimeters (7 inches) deep, the bottom of the trench is in shadow and more difficult to observe than other trenches that Phoenix has dug. The Phoenix team obtained spectral clues about the composition of material from the bottom of Stone Soup by photographing Caterpillar through 15 different filters of the Surface Stereo Imager when the pile was covered in freshly excavated material from the trench. The spectral observation did not produce any sign of water-ice, just typical soil for the site. However, the bigger clumps do show a platy texture that could be consistent with elevated concentration of salts in the soil from deep in Stone Soup. The team chose that location as the source for a soil sample to be analyzed in the lander's wet chemistry laboratory, which can identify soluble salts in the soil. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory

  3. Climate Drives Polar Bear Origins

    Science.gov (United States)

    In their provocative analysis of northern bears (“Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar bears originated during the middle Pleistocene, rather than during t...

  4. 海洋平台打桩过程中溜桩对桩基影响的研究%Influence of Pile Sinking on Pile Capacity during Pile Driving on Offshore Platforms

    Institute of Scientific and Technical Information of China (English)

    李飒; 王耀存; 蒲玉成; 孙振平; 樊之夏; 韩亮

    2014-01-01

    打桩过程中突然快速的溜桩可能造成脱锤,桩体破坏,引发安全事故。由于溜桩的产生往往造成打桩锤击数的预测值与实测值具有较大的偏差,此时准确评价溜桩后桩基承载力就成为实际工程中非常关注的问题。本文选择我国东海两个工程实例,根据现场高应变动测试验和打桩记录,研究了溜桩对桩基承载力的影响。计算分析显示,溜桩的产生会导致打桩总能量的明显降低;现场动测试验结果显示,溜桩发生后在发生溜桩的土层的桩体侧摩阻力接近于零,而桩端阻力没有明显的异常,说明溜桩导致的承载力降低主要来自于侧摩阻力的减小。在本文的实例中,溜桩导致的桩基承载力的降低最大可以达到桩基承载力计算值的17%。%Pile sinking during pile driving is common.A sudden drop of a pile after a strike from the hammer may cause a serious accident,such as the pile falling out of the drive cap or damage to the pile from high tension stress.Pile sinking also often causes a large deviation between the drivabili-ty prediction and the measured blow count.Therefore,an accurate assessment of pile capacity af-ter pile sinking becomes an important problem to address in practice.In this paper,two projects in the East China Sea are chosen to analyze.Based on the results of dynamic load tests in the field and pile driving records,the influence of pile sinking on pile capacity at the end of driving (EOD) is studied.The analysis results show that pile sinking will lead to a significant decrease in the total energy used in pile driving.The results from CAPWAP show that the unit friction of a soil layer where piles run off is close to zero,while the pile end resistance shows no obvious abnormalities. This indicates that the decrease in pile capacity caused by pile sinking is mainly from friction re-duction.In this instance,the pile capacity reduction resulting from pile sinking

  5. Development of in-pile test and evaluation technology

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Yung Hwan; Park, Jong Man; Joo, Kee Nam; Park, Duk Keun; Park, Se Jin; Oh, Jong Myung; Kim, Tae Ryong; Park Jin Suk; Lee, Jae Han [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1994-08-01

    To develop the in-pile test and evaluation technologies using KMRR, basic design of instrumented capsule and auxiliary system for material irradiation test and the related studies are performed. First, reactor and test hole characteristics are summarized, and conceptual design requirements of capsule to KMRR are reviewed. And fundamental principles and criteria for the instrumented capsule design are summarized. Basic design and analysis of instrumented capsule are performed, and design of capsule supporting system are also performed and structural integrity of the system is analyzed. Based on the prior studies, test mock-ups are designed and manufactured, and thermohydraulic and vibration tests are prepared. And, as in-pile test evaluation technologies, KMRR neutron dosimetry and mechanical tests related to material irradiation are investigated. 67 figs, 30 tabs, 41 refs. (Author).

  6. Probability distributions for Poisson processes with pile-up

    CERN Document Server

    Sevilla, Diego J R

    2013-01-01

    In this paper, two parametric probability distributions capable to describe the statistics of X-ray photon detection by a CCD are presented. They are formulated from simple models that account for the pile-up phenomenon, in which two or more photons are counted as one. These models are based on the Poisson process, but they have an extra parameter which includes all the detailed mechanisms of the pile-up process that must be fitted to the data statistics simultaneously with the rate parameter. The new probability distributions, one for number of counts per time bins (Poisson-like), and the other for waiting times (exponential-like) are tested fitting them to statistics of real data, and between them through numerical simulations, and their results are analyzed and compared. The probability distributions presented here can be used as background statistical models to derive likelihood functions for statistical methods in signal analysis.

  7. ESTIMATION OF SCOUR HOLE PROPERTIES AROUND VERTICAL PILE USING ANNs

    Institute of Scientific and Technical Information of China (English)

    A.KHOSRONEJAD; G. A. MONTAZER; M. GHODSIAN

    2003-01-01

    Correct estimation of the scour around vertical piles in the field exposed to oscillatory waves is very important for many offshore structures and coastal engineering projects. Conventional predictive formulas for the geometric properties of scour hole, however, are not able to provide sufficiently accurate results. Artificial Neural Networks (ANNs) are simplified mathematical representation of the human brain. Three-layer normal feed-forward ANN is a powerful tool for input-output mapping and has been widely used in civil engineering problems. In this article the ANNs approach is used to predict the geometric properties of the scour around vertical pile. Two different ANNs including multilayer perceptron (with four different learning rules) and radial basis functions neural networks are used for this purpose. The results show that a three-layer normal feed-forward multilayer perceptron with quick propagation (QP) learning rule can predict the scour hole properties successfully.

  8. The Supercritical Pile Model: Prompt Emission Across the Electromagnetic Spectrum

    Science.gov (United States)

    Kazanas, Demos; Mastichiadis, A.

    2008-01-01

    The "Supercritical Pile" GRB model is an economical model that provides the dissipation necessary to convert explosively the energy stored in relativistic protons in the blast wave of a GRB into radiation; at the same time it produces spectra whose luminosity peaks at 1 MeV in the lab frame, the result of the kinematics of the proton-photon - pair production reaction that effects the conversion of proton energy to radiation. We outline the fundamental notions behind the "Supercritical Pile" model and discuss the resulting spectra of the prompt emission from optical to gamma-ray energies of order Gamma^2 m_ec^2, (Gamma is the Lorentz factor of the blast wave) present even in the absence of an accelerated particle distribution and compare our results to bursts that cover this entire energy range. Particular emphasis is given on the emission at the GLAST energy range both in the prompt and the afterglow stages of the burst.

  9. Pile-Reinforcement Behavior of Cohesive Soil Slopes: Numerical Modeling and Centrifuge Testing

    Directory of Open Access Journals (Sweden)

    Liping Wang

    2013-01-01

    Full Text Available Centrifuge model tests were conducted on pile-reinforced and unreinforced cohesive soil slopes to investigate the fundamental behavior and reinforcement mechanism. A finite element analysis model was established and confirmed to be effective in capturing the primary behavior of pile-reinforced slopes by comparing its predictions with experimental results. Thus, a comprehensive understanding of the stress-deformation response was obtained by combining the numerical and physical simulations. The response of pile-reinforced slope was indicated to be significantly affected by pile spacing, pile location, restriction style of pile end, and inclination of slope. The piles have a significant effect on the behavior of reinforced slope, and the influencing area was described using a continuous surface, denoted as W-surface. The reinforcement mechanism was described using two basic concepts, compression effect and shear effect, respectively, referring to the piles increasing the compression strain and decreasing the shear strain of the slope in comparison with the unreinforced slope. The pile-soil interaction induces significant compression effect in the inner zone near the piles; this effect is transferred to the upper part of the slope, with the shear effect becoming prominent to prevent possible sliding of unreinforced slope.

  10. Calculation method of composite foundation sedimentation of grouting pile with cover plate under embankment load

    Institute of Scientific and Technical Information of China (English)

    顾长存; 洪昌地; 马文彬; 李雪平

    2008-01-01

    Grouting pile is a new soft soil foundation treatment method with characteristics such as no vibration, no noise, no soil compaction, light construction machines and quick construction velocity and so on. At present, study on reinforcement mechanism and design calculation method of composite foundation of grouting pile is initially started without design specifications, so it is usually required to draw on design specifications of stump pile when designing composite foundation of grouting pile while grouting pile has its characteristics and difference although reinforcement mechanisms and construction processes of two types of piles are similar. Sedimentation formula of composite foundation of grouting pile with cover plate is educed and a suitable deformation mode is proposed by aiming to deformation characteristics of composite foundation of grouting pile with cover plate under embankment load on basis of relevant sedimentation theories of composite foundation by combination of characteristics of composite foundation of grouting pile. The sedimentation calculation formula of grouting pile with cover plate under embankment load is educed according to balance relation of force and displacement coordination conditions by elastic theory and sedimentation calculation model established is validated by sedimentation monitoring documents of one expressway in China.

  11. Vibration from underground railways: considering piled foundations and twin tunnels

    OpenAIRE

    Kuo, Kirsty Alison

    2011-01-01

    Accurate predictions of ground-borne vibration levels in the vicinity of an underground railway are greatly sought after in modern urban centers. Yet the complexity involved in simulating the underground environment means that it is necessary to make simplifying assumptions about this system. One such commonly made assumption is to ignore the effects of nearby embedded structures such as piled foundations and neighbouring tunnels. Through the formulation of computationally efficient mathe...

  12. Collapse mechanisms and strength prediction of reinforced concrete pile caps

    DEFF Research Database (Denmark)

    Jensen, Uffe G.; Hoang, Linh Cao

    2012-01-01

    This paper describes an upper bound plasticity approach for strength prediction of reinforced concrete pile caps. A number of collapse mechanisms are identified and analysed. The procedure leads to an estimate of the load-carrying capacity and an identification of the critical collapse mechanism........ It is argued that the upper bound approach may be a useful complement to the widely used lower bound strut-and-tie method. Especially when dealing with strength assessment of existing structures....

  13. Analysis of Sandia in-pile EOS experiments

    International Nuclear Information System (INIS)

    Preliminary analysis has been carried out of the dynamic in-pile equation-of-state measurements for UO2, conducted at Sandia Laboratories, aimed at reducing the uncertainties in the effective UO2 enthalpy corresponding to the measured pressures. Of the remaining width of the p-H band of some 350 J/g, about 200 J/g originate in the uncertainties of the analytical modelling and about 150 J/g result from the scatter in the experimental data

  14. Analytical Constraints on Rubble Pile Fission, Dynamics and End States

    Science.gov (United States)

    Scheeres, Daniel Jay; Gabriel, Travis

    2015-08-01

    Recent progress in the study and analysis of rubble pile asteroids has focused on the numerical simulation of self-gravitating collections of rigid components that can rest on each other. These simulations are complex and can model thousands of grains interacting with each other, but due to this can sometimes present barriers to the understanding of their behavior in terms of fundamental physical principles.To address this we have embarked on an analytical study of the energetics and stability of few-body granular mechanics systems, comprised of gravitationally attracting elements that can rest on each other and transmit surface forces through friction or cohesion. These studies have primarily focused on simple shapes such as spheres and ellipsoids in contact. We have found that rigorous results can be placed on the stability of these resting and orbiting configurations as a function of their total angular momentum. These results shed direct light into the manner in which rubble pile asteroids can fail and what stable configurations they can settle in, accounting only for internal forces and dynamics. We note that these studies are also applicable for the accumulation stage of a rubble pile formation, following the catastrophic disruption of its parent body.There are several fundamental results from these analyses that have physical implications. A notable result provides conditions for when fissioned rubble piles can escape from each other, or conversely remain bound. It is significant that recent observations of asteroid pairs are consistent with these limits. Another result is that when a given configuration becomes unstable due to an increase in its total angular momentum (for example due to YORP), that it may sometimes settle into one of several stable configurations depending on how its energy is dissipated. This introduces a level of indeterminacy into the physical evolution of gravitational aggregates, and motivates the development of statistical approaches

  15. CFG Pile Quality Investigation and Production of Pile-cutting Equipment%CFG桩头质量调查及截桩设备的制作

    Institute of Scientific and Technical Information of China (English)

    刘红峰

    2013-01-01

    本文在总结钻孔桩桩头超灌高度的基础上,通过试验,提出CFG桩超灌高度为0.5m以上,制作并使用特制截桩设备大大减小了截桩对CFG桩的扰动,此外还对桩间土的开挖进行了详细论述。%Based on the summary of extra filling height of bored pile, through experiment, the paper points out the extra filling height of CFG pile is above 0.5m. The special pile-cutting equipment greatly reduced the disturbance of CFG pile. Additionally, it describes the excavation of soil between piles in detail.

  16. NEET In-Pile Ultrasonic Sensor Enablement-Final Report

    Energy Technology Data Exchange (ETDEWEB)

    J. Daw; J. Rempe; J. Palmer; P. Ramuhalli; R. Montgomery; H.T. Chien; B. Tittmann; B. Reinhardt; P. Keller

    2014-09-01

    Ultrasonic technologies offer the potential to measure a range of parameters during irradiation of fuels and materials, including geometry changes, temperature, crack initiation and growth, gas pressure and composition, and microstructural changes under harsh irradiation test conditions. There are two primary issues that currently limit in-pile deployment of ultrasonic sensors. The first is transducer survivability. The ability of ultrasonic transducer materials to maintain their useful properties during an irradiation must be demonstrated. The second issue is signal processing. Ultrasonic testing is typically performed in a lab or field environment, where the sensor and sample are accessible. The harsh nature of in-pile testing and the variety of desired measurements demand that an enhanced signal processing capability be developed to make in-pile ultrasonic sensors viable. To address these issues, the NEET ASI program funded a three year Ultrasonic Transducer Irradiation and Signal Processing Enhancements project, which is a collaborative effort between the Idaho National Laboratory, the Pacific Northwest National Laboratory, the Argonne National Laboratory, and the Pennsylvania State University. The objective of this report is to document the objectives and accomplishments from this three year project. As summarized within this document, significant work has been accomplished during this three year project.

  17. Radial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while

  18. Partial tooth gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  19. Blood Pump Bearing System

    Science.gov (United States)

    Aber, Gregory S. (Inventor)

    2000-01-01

    An apparatus is provided for a blood pump bearing system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  20. 开口钢管桩沉桩阻力研究%Research of pile-sinking resistance of small aperture opening steel pipe pile

    Institute of Scientific and Technical Information of China (English)

    曹书文; 赵冬; 陈平; 张卫喜

    2012-01-01

    To get the pile-sinking resistance calculation formula of small aperture opening steel pipe pile, the plugging effect, squeezing effect and strain softening effect of open ended steel pipe pile are analyzed. The pile-sinking resistance formula is proposed combined with cone penetration test, the pile-sinking process is divided into two stages: before and after inner soil blocked, and the fitting coefficients of pile side resistance and pile tip resistance are calculated respectively, and the two stages pile-sinking resistance calculation formula of small aperture opening steel pipe pile is obtained. The results fit the test dates in engineering well. The research results can provide reference to pit-jacked steel pipe pile in Huanghe alluvial plain silt soil.%为得到小直径开口钢管桩的沉桩阻力计算公式,对开口钢管桩的土塞效应、挤土效应和软化效应进行了分析,结合静力触探原理,提出了沉桩阻力计算公式,将沉桩过程分为土塞闭合前后两个阶段,分别计算了桩侧阻力和桩端阻力的拟合系数,得到了小直径开口钢管桩的两阶段沉桩阻力计算公式.与工程实际测试数据符合较好.结果为黄河冲积平原粉土土质的坑式钢管静压桩提供了工程参考.