WorldWideScience

Sample records for geogrids

  1. Slope reinforcement design using geotextiles and geogrids

    Science.gov (United States)

    Setser, Darrell M.

    1990-08-01

    A geotextile is defined by ASTM as: any permeable textile material used with foundation, soil, rock, earth, or any other geotechnical engineering related material, as a integral part of a man-made project, structure, or system. A geogrid is defined as: any geotextile-related material used in a similar manner to geotextiles. They are usually made of plastic, but can be metal or wood. Geotextiles and geogrids are collectively referred to as geosynthetics in this paper. Geosynthetic reinforcement of slopes is a relatively new option available to the civil engineer. Slope angles can be increased and 'poor' soil can be used to construct economical soil-geosynthetic facilities. Uncertainties exist in the complex interaction between the soil and the geosynthetic but there are numerous procedures which ignore this in the design. The design procedures available may be conservative yet still may be an economical alternative when compared to more conventional options.

  2. Development and Properties of Glass Fiber Reinforced Plastics Geogrid

    Institute of Scientific and Technical Information of China (English)

    WANG Qingbiao; ZHANG Cong; WEN Xiaokang; L Rongshan; LIANG Xunmei; LU Shide

    2015-01-01

    Glassfi ber reinforced plastics geogrid has a wide application in thefi eld of soil reinforcement because of its high strength, good toughness, and resistance to environmental stress, creep resistance and strong stability. In order to get high-powered glassfi ber reinforced plastics geogrid and its mechanical characteristics, the properties and physical mechanical index of geogrid have been got through the study of its raw material, production process and important quality index. The analysis and study have been made to the geogrid’s mechanical properties with loading speed, three-axial compression, temperature tensile test and FLAC3D numerical simulation, thus obtain the mechanical parameters of its displacement time curve, breaking strength and elongation at break. Some conclusions can be drawn as follows: (a) Using glassfi ber materials, knurling and coated projection process, the fracture strength and corrosion resistance of geogrid are greatly improved and the interlocking bite capability of soil is enhanced. (b) The fracture strength of geogrid is related to temperature and loading rate. When the surrounding rock pressure is fixed, the strength and anti-deformation ability of reinforced soil are significantly enhanced with increasing reinforced layers. (c) The pullout test shows the positive correlation between geogrid displacement and action time. (d) As a new reinforced material, the glass fi ber reinforced plastics geogrid is not mature enough in theoretical research and practical experience, so it has become an urgent problem both in theoretical study and practical innovation.

  3. Mechanism of Geogrid Reinforced Soil at Bridge Approach

    Institute of Scientific and Technical Information of China (English)

    FENG Guangle; LUO Rong; CHEN Congxin

    2007-01-01

    Using Geogrid-Reinforced Soil (GRS) we studied the working mechanism and design method of GRS at bridge approach with high backfill by field experiment. In a highway section where the height of backfill is 13.5 meters, geogrids were used at two bridge approaches to address the bumping problems. Some soil pressure cells were used to measure the normal and lateral soil pressure at different locations in the roadbed. The experimental results indicate that geogrids in geogrid-reinforced soil (GRS) could produce an uplift force, the closer the location to the abutment, the larger the uplift force, and the reduction of measured soil pressures compared with theoretical values was the largest at the bottom of roadbed, less at the top than at the bottom, and the least in the mid-height of roadbed than at the bottom. These findings are different from those of the traditional greogrid-reinforced subgrade design method.

  4. Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope.

    Science.gov (United States)

    Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie

    2017-03-15

    By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogrid-reinforced slopes. In this paper, a geogrid-reinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software Midas-GTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogrid-reinforced sand slopes.

  5. Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope

    Science.gov (United States)

    Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie

    2017-01-01

    By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogrid-reinforced slopes. In this paper, a geogrid-reinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software Midas-GTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogrid-reinforced sand slopes. PMID:28294995

  6. Influence of Vehicle Load as Point Load on Geogrid Deformation as Embankment Reinforcement on Soft Soil

    Directory of Open Access Journals (Sweden)

    A. Adhe Noor Patria SH

    2012-02-01

    Full Text Available Public contructions built on soft soil such as clay would face some problems such as long period consolidation time, unstability embankment slope, not easily compacted and high level settlement. Some solution that could be suggested were the usage of vertical drain, or the usage of geosynthetics material such as geogrid combined with floating piles. Analysis was carried out by using plaxis version 7.2. soil for embankment and embankment foundation was modelled in plane strain. Also geogrid and floating piles were modelled in plane strain too. Point load on top of embanknet were variated, they were 20, 40 and 60 kN/m. The simulation was carried out in staged contruction mode. The implementation of vehicle load increased geogrid deformation. It appeared as geogrid vertical displacement when the biggest vehicle load ( 60 kn/m applied. In long term loading condition where excess pore water pressure was very small, vertical displacement of geogrid was – 0,5062 m for rigid embankment and – 0,6568 m for interface embankment. The difference occured due to slip at the interface of geogrid and soil. It leaded to adding soil mass supported by geogrid, furthermore the deflection of geogrid became bigger.

  7. Behavior of geogrid-reinforced ballast under various levels of fouling

    Energy Technology Data Exchange (ETDEWEB)

    Indraratna, B.; Ngo, T.; Rujikiatkamjorn, C. [University of Wollongong, Wollongong, NSW (Australia)

    2011-06-15

    This paper presents a study of how the interface between ballast and geogrid copes with fouling by coal fines. The stress-displacement behavior of fresh and fouled ballast, and geogrid reinforced ballast was investigated through a series of large-scale direct shear tests where the levels of fouling ranged from 0% to 95% Void Contamination Index (VCI), at relatively low normal stresses varying from 15 kPa to 75 kPa. The results indicated that geogrid increases the shear strength and apparent angle of shearing resistance, while only slightly reducing the vertical displacement of the composite geogrid-ballast system. However, when ballast was fouled by coal fines, the benefits of geogrid reinforcement decreased in proportion to the increasing level of fouling. A conceptual normalized shear strength model was proposed to predict this decrease in peak shear stress and peak angle of shearing resistance caused by coal fines at a given normal stress.

  8. Material Properties and Tensile Behaviors of Polypropylene Geogrid and Geonet for Reinforcement of Soil Structures

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The properties and tensile behaviors of polypropylene (PP) geogrids and geonets for reinforcement of soil structures are investigated.Mass per unit area of the geogrids and geonets was weighed using an electronic balance and aperture sizes of the geonets were exactly measured using a computer.Laboratory tests were performed using a small tensile machine capable of monitoring tensile force and displacement.Tensile failure behaviors were described,and tensile index properties such as tensile strength,maximum tensile strain,tensile forces corresponding to different strains in the geogrids and gronets were obtained.The characterization of these indexes is discussed.

  9. Pengaruh Beban Kendaraan sebagai Beban Terbagi Rata terhadap Deformasi Geogrid sebagai Perkuatan Embankment

    Directory of Open Access Journals (Sweden)

    Adhe Noor Patria

    2012-02-01

    Full Text Available Soft soil such as clay was sensitive soil. Public contructions built in this kind of soil would face some problemssuch as long period consolidation time, unstable embankment slope, not easily compacted and high level settlement. Some solution that could be suggested were the usage of vertical drain, or the usage of geosynthetics material such as geogrid combined with floating  piles.Analysis was carried out by using plaxis version 7.2. soil for embankment and embankment foundation was modelled in plane strain. Also geogrid andfloating piles were modelled in palne strain too. Surcharge load on top of embanknet were variated, they were 20, 35 and 50 kPa. The simulation was carried out in staged contruction mode.Final vertical displacement in geogrid due to 50  kPa vehicle load as surcharge load and long term load period (in this case excess pore water pressure was small was -0,9062 m for  rigid embankment and -1,4206 for interface embankment. The difference occured due to slip at the interface of geogrid and soil. It  leaded to adding soil mass supportd by geogrid, furthermore the deflection of geogrid became bigger.

  10. Improvement of Bearing Capacity of Shallow Foundation on Geogrid Reinforced Silty Clay and Sand

    Directory of Open Access Journals (Sweden)

    P. K. Kolay

    2013-01-01

    Full Text Available The present study investigates the improvement in the bearing capacity of silty clay soil with thin sand layer on top and placing geogrids at different depths. Model tests were performed for a rectangular footing resting on top of the soil to establish the load versus settlement curves of unreinforced and reinforced soil system. The test results focus on the improvement in bearing capacity of silty clay and sand on unreinforced and reinforced soil system in non-dimensional form, that is, BCR. The results show that bearing capacity increases significantly with the increased number of geogrid layers. The bearing capacity for the soil increases with an average of 16.67% using one geogrid layer at interface of soils with equal to 0.667 and the bearing capacity increases with an average of 33.33% while using one geogrid in middle of sand layer with equal to 0.33. The improvement in bearing capacity for sand underlain silty clay maintaining and equal to 0.33; for two, three and four number geogrid layer were 44.44%, 61.11%, 72.22%, respectively. The finding of this research work may be useful to improve the bearing capacity of soil for shallow foundation and pavement design for similar type of soil available elsewhere.

  11. Experimental study on visco-elastic constitutive relationship and its parameters for geogrids

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Geogrids are used as reinforcement materials widely in geotechnical and civil engineering fields. In this paper, a series of comparative tests on creep behavior of specific geo0grids are conducted in the laboratory under different combinations of loading levels and environmental temperature. Based on the test results, comparative analyses are made to study long-term behaviors of isochronous load-strain curves, creep curves and relaxation curves for the specified geogrids. Furthermore, a constitutive model based on theory of visco-elasticity and tests results is proposed for geogrids and a rational procedure is presented in detail for determining the relevant parameters of the proposed model. Finally, the effect of tests temperature on model parameter values is investigated.

  12. INVESTIGATION OF INNER SHEAR RESISTANCE OF GEOGRIDS BUILT UNDER GRANULAR PROTECTION LAYERS AND RAILWAY BALLAST

    Directory of Open Access Journals (Sweden)

    Sz. Fischer

    2015-10-01

    Full Text Available Purpose. Using adequate granular materials and layer structures in the railway super- and substructure is able to stabilise railway track geometry. For this purpose special behaviour of above materials has to be determined, e.g. inner shear resistance. Inner shear resistance of granular media with and without geogrid reinforcement in different depths is not known yet. Methodology. The author developed a special laboratory method to measure and define inner shear resistance of granular materials, it is called «multi-level shear box test». This method is adequate to determine inner shear resistance (pushing force vs. depth (distance from the «zero» surface. Two different granular materials: andesite railway ballast (31.5/63 mm and andesite railway protection layer material (0/56 mm, and seven different types of geogrids (GG1…GG7 were used during the tests. Findings. Values of inner shear resistance functions of andesite railway ballast without geogrid reinforcement and reinforced with different types of geogrids and andesite granular protection layer in function of the vertical distance from the geogrid plane were determined with multi-layer shear box tests when the material aggregation is uncompacted and compacted. Only the compacted sample was tested in case of the 0/56 mm protection layer. Cubic polynomial regression functions fitted on the mean values of the measurements are described graphically. Determination coefficients with values of R2>0.97 were resulted in all the cases of regression functions. Based on the polynomial regression functions fitted on the mean values of the test results, three increasing factors were determined in function of the distance measured from the geogrid. Increasing factor «A», «B» and «D». Originality. Multi-level shear box test, developed by the author, is certified unequivocally adequate for determining inner shear resistance of reinforced and unreinforced granular materials, e.g. railway ballast

  13. Evaluation of Interface Shear Strength Properties of Geogrid Reinforced Foamed Recycled Glass Using a Large-Scale Direct Shear Testing Apparatus

    Directory of Open Access Journals (Sweden)

    Arul Arulrajah

    2015-01-01

    Full Text Available The interface shear strength properties of geogrid reinforced recycled foamed glass (FG were determined using a large-scale direct shear test (DST apparatus. Triaxial geogrid was used as a geogrid reinforcement. The geogrid increases the confinement of FG particles during shear; consequently the geogrid reinforced FG exhibits smaller vertical displacement and dilatancy ratio than FG at the same normal stress. The failure envelope of geogrid reinforced FG, at peak and critical states, coincides and yields a unique linear line possibly attributed to the crushing of FG particles and the rearrangement of crushed FG after peak shear state. The interface shear strength coefficient α is approximately constant at 0.9. This value can be used as the interface parameter for designing a reinforced embankment and mechanically stabilized earth (MSE wall when FG is used as a lightweight backfill and triaxial geogrid is used as an extensible earth reinforcement. This research will enable FG, recently assessed as suitable for lightweight backfills, to be used together with geogrids in a sustainable manner as a lightweight MSE wall. The geogrid carries tensile forces, while FG reduces bearing stresses imposed on the in situ soil. The use of geogrid reinforced FG is thus significant from engineering, economical, and environmental perspectives.

  14. Experimental Study on Performance of Multidirectional Geogrid and Its Application in Engineering of High Slope

    Institute of Scientific and Technical Information of China (English)

    WANG Qingbiao; WEN Xiaokang; JIANG Jinquan; ZHANG Cong; SHI Zhenyue

    2014-01-01

    By analyzing the grille mechanical property, tensile strength and creep tests, and the field tests, we investigated the characteristics and the reinforcement principle of multidirectional geogrid, and obtained the effect factors of grid characteristics, load and time curve and the shear stress of grille and sand interface. The reinforcement effect of geogrid in combination of typical project cases was illustrated and the following conclusions were presented. Firstly, multidirectional geogrid has ability to resist structural deformation, node distortion or soil slippage under stress, and can effectively disperse load. Secondly, with the increase of tensile rate, grille intensity increases and the creep value also increases with the increase of load. Thirdly, the frictional resistance balance between horizontal thrust of damaged zone and reinforced soil in stable region can avoid slope failure due to excessive lateral deformation. Fourthly, the multidirectional geogrid is able to withstand the vertical, horizontal and diagonal forces by combing them well with three-dimensional orientation, realizing the purpose of preventing soil erosion and slope reinforcement, which has a wide range of application and development in engineering field.

  15. Numerical Investigation Into The Behavior of Circular Pad Shallow Foundations Supported By Geogrid Reinforced Sand

    Directory of Open Access Journals (Sweden)

    S. M. Marandi

    2008-01-01

    Full Text Available This study seeks to widen the pool of knowledge on the use and characteristics of geosynthetics, specifically in the area of circular foundations supported by geosynthetic reinforced sand. The main objective of the work was to increase the awareness of circular foundation systems and thus increase the accuracy of current laboratory methods. Also, compare the results with that of previous papers on the subject and to provide new model curves to estimate the bearing capacity of circular foundations. In this respect, the foundation and the soil underneath was modeled using four nots isoparameters finite element aid, while, for geogrid reinforcement, the four nots one-dimentional finite element model was used. The sand behavior was based on demolition elasto-plastic drucker-prager criteria and for the reinforcement the linear criteria was used. The paper investigates the effects of the reinforcement placing properties, soil properties, reinforcement properties, and the geometric properties of circular foundations. The results showed that; the bearing capacity ratio at a settlement level for geogrid reinforced sand is effected considerably by parameters such as: reinforcement placement, reinforcement layers, reinforcement strength, geometric properties of circular foundations, and effects of using granular soils. Based on the results achieved, a number of design curves have been developed to assist with the estimation (design of field bearing capacity of shallow foundations supported by geogrid reinforced soil. Keeping in mind the settlement limitations in real space, the curves have been developed for normal settlement levels up to a settlement ratio of 2.5%.

  16. Load eccentricity effects on behavior of circular footings reinforced with geogrid sheets

    Directory of Open Access Journals (Sweden)

    Ehsan Badakhshan

    2015-12-01

    Full Text Available In this paper, an experimental study for an eccentrically loaded circular footing, resting on a geogrid reinforced sand bed, is performed. To achieve this aim, the steel model footing of 120 mm in diameter and sand in relative density of 60% are used. Also, the effects of depth of first and second geogrid layers and number of reinforcement layers (1–4 on the settlement-load response and tilt of footing under various load eccentricities (0 cm, 0.75 cm, 1.5 cm, 2.25 cm and 3 cm are investigated. Test results indicate that ultimate bearing capacity increases in comparison with unreinforced condition. It is observed that when the reinforcements are placed in the optimum embedment depth (u/D = 0.42 and h/D = 0.42, the bearing capacity ratio (BCR increases with increasing load eccentricity to the core boundary of footing, and that with further increase of load eccentricity, the BCR decreases. Besides, the tilt of footing increases linearly with increasing settlement. Finally, by reinforcing the sand bed, the tilt of footing decreases at 2 layers of reinforcement and then increases by increasing the number of reinforcement layers.

  17. Evaluation of parameters affecting reflection cracking in geogrid-reinforced overlay

    Institute of Scientific and Technical Information of China (English)

    Shahab Fallah; Ali Khodaii

    2015-01-01

    The influence of the most important parameters on the service life of reinforced asphalt overlay with geogrid materials in bending mode was examined by employing the Taguchi method and analysis of variance techniques. The objectives of this experiment was to investigate the effects of grid stiffness, tensile strength, coating type, amount of tack coat, overlay thickness, crack width and stiffnesses of asphalt overlay and existing asphalt concrete on propagation of the reflection cracking. Results indicate that the stiffnesses of cracked layer and overlay are the main significant factors that can directly improve the service life of an overlay against the reflection cracking. Generally, glass grid is more effective in reinforced overlay than polyester grid. Effect of crack width of the existing layer is significant when its magnitude increases from 6 to 9 mm.

  18. 土工格栅加筋路堤有限元分析%The Finite Element Analysis of Geogrid Reinforced Embankment

    Institute of Scientific and Technical Information of China (English)

    马希磊; 李致朋; 许夏伟

    2011-01-01

    In this paper,geogrid reinforced embankment is simulated with the finite element software ANSYS, expound the role of reinforced soil reinforcement principle. Four different geogrid reinforced embankments included unreinforced embankmcnt, sand cushion embankment, one layer of geogrid embankment , two layers of geogrid embankment are calculated with an engineering example. Analyse the impact of reinforced soil on subgrade's lateral displacement, vertical displacement, vertical stress, shear stress and tension of reinforcement under different reinforced methods.%通过有限元软件ANSYS对土工格栅加筋路堤进行模拟,阐述了加筋土的加筋作用原理.通过一个工程实例分别对不加筋、仅加砂垫层、加一层土工格栅砂垫层、加两层土工格栅砂垫层四种不同的加筋路堤进行了计算.分析了不同加筋方式下加筋土路基竖向位移、侧向位移、竖向应力、剪应力和筋材拉力的规律.

  19. Studies on Geogrid Encased Stone Column of Bearing Capacity%包裹碎石桩承载力分析

    Institute of Scientific and Technical Information of China (English)

    齐云龙; 任海波

    2016-01-01

    The Geogrid encased stone column is the type of encased a stone column with geo-grid.In order to make further study on geogrid encased stone column,a laboratory model study is conduc-ted.The P -s curves is based on the load on the bearing plate and the settlement on the bearing plate.The axial force is obtained by placing sensors in the pile body.From the axial force,the load trans-fer mechanism,the tip resistance and the skin friction are studied.From the experiment results,the geo-grid encased stone column effectively improve the load performance of the soil.The geogrid encased stone column exists pressure mainly within 0.7l (5.6 d)depth during the loading.There is about 40% of the pressure on the pile top at a depth of three times pile diameter;And it is about 20% of the pressure on the pile top at a depth of 5.6 times pile diameter.What's more,it exists pressure at a depth of eight times diameter(pile bottom)when the pressure at plate top larger than 85 kPa.%包裹碎石桩是在碎石桩外包裹一层土工材料制成的一种桩体。为了更好地研究这种桩体的承载力情况,进行室内模型试验。由所加荷载和承压板沉降值得到了承载力-沉降曲线,在桩体内布置土压力盒,实测桩身轴力,研究了包裹碎石桩的荷载传递情况、端阻力和侧摩阻力。通过试验发现包裹碎石桩有效地提高了未加固地基的承载力。包裹碎石桩承受竖向荷载时,主要在桩身0.7 l(5.6 d)(l、d 分别为桩长和桩径)深度范围内存在力的作用;在3 d 深度的应力约为桩顶应力的40%,5.6 d 深度的应力约为桩顶应力的20%,当外部压力大于85 kPa 时,8 d 深度(桩底端)存在应力。

  20. Soil Improvement By Jet Grout Method And Geogrid Against Liquefaction: Example Of Samsun-Tekkeköy

    Science.gov (United States)

    Öztürk, Seda; Banu İkizler, S.; Şadoǧlu, Erol; Dadaşbilge, Ozan; Angın, Zekai

    2017-04-01

    scenarios of earthquakes with 6.0, 6.5, 7.0 and 7.2 magnitudes. As a result of the analyses made, it has been deemed necessary to improve the soil in order to prevent or reduce the liquefaction effects which may occur in a possible earthquake due to the presence of liquefaction potential in the research area. For this purpose, jet grouting method and geogrid fill system, which are used widely in Turkey, have been chosen as appropriate improvement methods. Geogrids are strong in tension so they are commonly used to reinforce subsoils below foundations. Additionally, jet grouting method provides high bearing capacity; it is solution to the settlement problems, it can be applied to almost any kind of soil and it has a short production period. Within this scope, optimal solution was obtained with 616 pieces of 8 m and 12 m jet grout columns with the diameter of 0.65 m and with geogrid mechanical fillings laid on jet grout columns. Thus, not only the risk of liquefaction was eliminated but also an improvement of more than 3 times of the bearing capacity of the foundation was acquired. In addition, the required quality control tests were carried out for the jet grout columns built in the research area and no adverse effects were observed. Key words: Liquefaction, soil improvement, jet grouting, geogrid

  1. Application of geogrid in sheet pile wharfs%土工格栅在板桩码头工程中的应用

    Institute of Scientific and Technical Information of China (English)

    张福贵; 朱庆华

    2009-01-01

    Based on geotechnicai principles, a method for determining the strength indices of compound soils with geogrid is put forward. A sheet pile wharf filled with compound soils, with the geogrid acting as reinforcement material behind the sheet pile wall, was analyzed. The proposed method was employed to determine the strength indices of the compound soils, and the stresses acting on the sheet pile wharf structure were analyzed. The results show that the strength of the compound soils behind the sheet pile wall can be improved by adding geogrid, which can also reduce the active soil pressure of the backfill soils on the sheet pile wall so as to optimize the sheet pile wharf structure and to reduce the construction cost. Engineering cases indicate the efficacy of reducing the soil pressure behind the sheet pile wall by using of the geogrid to reinforce the backfill soils.%基于土工原理,提出了一种计算土工格栅复合土体强度指标的分析方法.针对板桩码头工程,在板桩墙后采用以土工格栅为筋材的复合土体进行回填,按照该计算方法确定复合土体的强度,并据此对板桩码头结构进行受力分析.结果表明:在板桩墙后的回填土体中加入土工格栅可以提高复合土体的强度,减小回填土体对板桩墙的主动土压力作用,从而优化板桩码头结构,降低工程造价.实际工程应用表明,在板桩码头板桩墙后采用土工格栅加筋回填土,对减少墙后土压力具有良好的效果.

  2. Application and Outlook of Geogrids to Frozen Subgrade%土工格栅在冻土路基中的应用及展望

    Institute of Scientific and Technical Information of China (English)

    陈榕; 郝冬雪; 鲁楠

    2014-01-01

    It is a worldwide problem that the treatment about the freeze-thaw disaster of subgrade in frozen soil region. Moreover,this disaster happened in seasonal frozen regions is bigger than that happened in the perma-frost regions. General construction technologies and treatments to subgrade in permafrost region are not suit for the seasonal frost region. The geogrid is widely used in geotechnical engineering projects, because of its net structure and mosaic capacity. Based on reinforced characters of geogrid and the performance of geogrid-rein-forced earth structure in permafrost regions, this paper proposes that geogrid could be chosen to treating the frost heaving,thaw settlement and frost boiling,then the feasibility is also discussed mainly from practical engi-neering and theoretical research in detail.%冻土地区路基冻融病害的整治,一直被视为世界性的难题。现有的常规施工工艺和方法在冻土地区均存在着一定的局限性。土工格栅凭借其独特的网状结构和镶嵌咬合能力,在国内外岩土工程中得到了广泛的应用。本文基于土工格栅的加筋特性和现有的格栅加筋工程的实际经验,建议可选择土工格栅可对冻土路基冻融灾害进行防治,并分别针对冻土地区常见的冻胀、融沉及翻浆灾害问题,从理论研究和工程实践方面阐述了其具有一定的实际应用性,并对其进行了应用展望。

  3. 高密度聚乙烯土工格栅光氧老化研究进展%Progress of Study on Photo-oxidation Aging of High Density Polyethylene Geogrids

    Institute of Scientific and Technical Information of China (English)

    蒋秀亭; 杨旭东; 童军

    2015-01-01

    对高密度聚乙烯( HDPE)土工格栅的光氧老化机理进行系统性的介绍;分析影响土工格栅光氧老化的外界因素,包括环境因素、安装损耗和加工方式等;同时介绍高密度聚乙烯土工格栅降解后性能的变化,从力学性能、外观变化及微观指标三方面总结其老化后的表征指标,并指出HDPE土工格栅光氧老化研究方面的不足。%In this paper,the mechanisms of High density polyethylene( HDPE) geogrids after photo-oxidation ag-ing are introduced systematically. Analyzed the influence factors for geogrids during photo-oxidation degradation,in-cluding environment factors,installation damages and processing methods. Simultaneously,introduced performance changes in the photo-oxidation of high density polyethylene geogrids,and summarized characterization of indicators from the mechanical properties,changes in appearance and microstructure indicators. Also pointed out deficiency at aspects of research and future research issues are analyzed for HDPE geogrids.

  4. 高填方土工格栅加筋土边坡稳定性研究%Stability Analysis of High Backifll Slope Reinforced by Geogrids

    Institute of Scientific and Technical Information of China (English)

    金永军; 燕慧晓; 阙金声; 何坤

    2015-01-01

    According to the stress characteristics of geogrids in the high backifll slope, based on simpliifed Bishop method,the calculation formula of slope stability coefifcient is deduced to consider earthquake, groundwater, slope surface load, slope top (foot) load, geogrids and other factors, which provides a method for more precise evaluation the stability of high backifll geogrids reinforced soil slope. According to the characteristics of high backifll slope with multiple steps, through the cut-into-point, cut-out-point and midpoint of sliding arc, a method of controlling position of sliding surface is proposed to determine the range of sliding arc midpoint, makes the slope potential arc sliding surface search experiential assumptions aren't required, programming simple, and the calculation efifciency of the minimum stability coefifcient of complex slope is effectively improved. This method also provides a good basis for the sensitivity analysis and reliability analysis of the slope design parameters.%针对高填方边坡中土工格栅的受力特点,在简化Bishop法的基础上推导了可以考虑地震、地下水、坡面荷载、坡顶(脚)荷载、土工格栅等因素的边坡稳定系数计算公式,为更精确地评价高填方土工格栅加筋土边坡稳定性研究提供了方法。针对高填方多台阶边坡的特点,通过滑动面剪入点、剪出点和滑弧中点控制滑动面位置,提出了确定滑弧中点取值范围的方法,使得边坡潜在圆弧滑动面的搜索范围不再需要经验假定,编程简单,并可有效提高复杂边坡最小稳定系数的计算效率,也为边坡设计参数的敏感性分析、可靠性分析提供很好的计算基础。

  5. Experimental study of engineering properties of geogrid-reinforced loess mixed with sand%土工格栅加筋掺砂黄土工程性质试验研究

    Institute of Scientific and Technical Information of China (English)

    胡幼常; 申俊敏; 赵建斌; 顾光斗; 蔡华南

    2013-01-01

    为了寻找实用而有效的方法来降低用黄土填筑的桥头路堤沉降并提高其强度以避免桥头跳车,提出了在黄土中掺砂、用土工格栅加筋或两种方法同时采用的建议。为了研究这些建议的可行性,采用室内回弹模量试验和无侧限抗压试验分别研究了土工格栅加筋黄土和加筋掺砂黄土的变形和强度特性。对黄土和掺砂黄土分别完成了压实度为88%、92%和96%,加筋层数为0~5层组合工况下多组试样的回弹模量和无侧限抗压试验,对试验结果进行了详细的对比分析,得到以下结论:(1)掺砂和土工格栅加筋都可以明显提高黄土的回弹模量,两种方法同时使用效果更佳;(2)不管有无土工格栅加筋,掺砂都能使黄土强度大幅度提高,尤其在小应变下其提高的幅度更大;(3)在压实度不变而加筋层数增多时,或加筋层数不变而压实度下降时,土工格栅加筋掺砂黄土的应力-应变曲线由应变软化型逐渐向应变硬化型转变;(4)加筋掺砂黄土存在筋-土强度合理匹配问题,压实度高时应布置较密的加筋层,以使二者变形协调,从而实现加筋掺砂黄土强度的最大化。%In order to find out an effective and practical approach to reduce the settlement and increase the strength of an approach embankment filled with loess so as to avoid the bump at bridgehead, the methods were suggested by mixing a proportion of sand into the loess or reinforcing the loess with geogrid, or by using these two skills together. For examining essentially the feasibility of these ideas, the deformation and strength properties of geogrid-reinforced loess, loess mixed with sand (LMS) and geogrid-reinforced LMS were investigated in laboratory. A series of resilient modulus tests and unconfined compression tests were conducted respectively using samples made up of LMS or pure loess either with or without geogrid

  6. Experimental investigation of geogrid-reinforced and pile-supported embankment on soils with medium-low compressibility%中低压缩性土地区桩承式加筋路堤现场试验研究

    Institute of Scientific and Technical Information of China (English)

    郑俊杰; 曹文昭; 董同新; 张军; 谢明星

    2015-01-01

    将桩承式加筋路堤技术应用于中低压缩性土地区高速铁路桥台和涵洞之间填方路基的处理,通过逐渐改变CFG桩桩长形成刚度均匀变化的地基加固区,严格控制线路纵向差异沉降.通过现场试验对桥台、涵顶和路基中心地基沉降进行了长期观测,同时对桩承式加筋路堤桩间土沉降、孔隙水压力、格栅上下表面土压力和格栅变形进行了长期监测分析.研究结果表明:桩承式加筋路堤可有效减小中低压缩性土地基沉降,总沉降小且很快趋于稳定;桩承式加筋路堤通过土拱效应和张拉膜效应将路堤荷载向桩帽传递,格栅下桩土应力比明显高于格栅上,张拉膜效应明显,格栅上桩土应力比接近1.0,土拱效应较弱;格栅在路肩处发挥的作用强于线路中心处.%The geogrid-reinforced and pile-supported embankment is adopted to treat the subgrade of high-speed railways between the bridge abutment and culvert on the soils with medium-low compressibility. The subgrade with uniformly variable stiffness is formed by varying the lengths of CFG piles gradually aiming at controlling the longitudinal differential settlement strictly. The settlements of bridge abutment, culvert and subgrade center are monitored based on full scale field tests. Meanwhile, the settlement of the surrounding soils of pile, the pore water pressure, the earth pressure above/below the geogrid, and the geogrid deformation are measured. The experimental results demonstrate that the total and layered settlements of the subsoils with medium-low compressibility are reduced effectively, and the total settlements are very small and reach the stable value soon. The embankment load is transferred to pile caps by the combined action of soil arching effect and tensioned membrane effect. The pile-soil pressure ratio below the geogrid is significantly larger than that above the geogrid, which suggests that an obvious tensioned membrane effect exists

  7. Nu merical simulation on electrothermal properties of geogrid reinforced asphalt concrete%格栅增强沥青混凝土电热性能数值模拟

    Institute of Scientific and Technical Information of China (English)

    宋世德; 周卫杰

    2016-01-01

    Carbon/glass fiber geogrid reinforced asphalt concrete is a new type of composite,which not only has good mechanical properties,but also shows excellent electrical conductivity.In this paper,the good electrother-mal properties of carbon/glass fiber geogrid reinforced asphalt concrete were used to heat the asphalt concrete slab,then melt snow and deice the ice.The environment temperature,the wind speed,the heating power and the thickness of ice are four main factors of the asphalt concrete slab deicing efficiency.In this paper,the deicing process of carbon/glass fiber geogrid reinforced asphalt concrete were simulated by ANSYS finite element software to predict deicing effect.The experimental values were used to verify the correctness of the numerical simulation. The results show that under various operating conditions,the numerical values are very close to the experimental values in the deicing process of carbon/glass fiber geogrid reinforced asphalt concrete.%利用碳/玻璃纤维格栅增强沥青混凝土的良好电热性能,使沥青混凝土板升温起到融雪化冰的作用。环境温度、风速、发热功率和冰层厚度是影响沥青混凝土板化冰效率的4个主要因素。应用ANSYS有限元软件对碳/玻璃纤维格栅增强沥青混凝土的化冰过程进行数值模拟来预测其化冰效果,并用试验结果验证有限元模拟的正确性。结果表明:在各种工况下,碳/玻璃纤维格栅增强沥青混凝土化冰过程的模拟值与试验值的吻合度比较高。

  8. 远红外加热技术应用于塑料土工格栅生产%APPLICATION OF THE FAR-INFRARED HEATING IN THE PRODUCTION OF PLASTICS GEOGRID

    Institute of Scientific and Technical Information of China (English)

    高洁; 朱复华

    2000-01-01

    远红外加热技术具有生产效率高、节约能源、提高产品质量、降低成本等特点。这一技术日趋成熟,广泛应用于生产和科研各个领域。实验表明,采用合理的设计原则和技术可将远红外加热技术应用于塑料土工格栅的生产。%The advantages of far-infrared heating include less production cost, high heating efficiency and increased productivity, etc. And now, this technique is gradually getting ripe and is applied in various fields. The test showes that if using suitable design principle and skill the far-infiared heating can be used in the production of geogrid.

  9. A Tentative Exploration on the Strength Design of the Geogrid in Geosynthetic-encased Stone Columns%加筋碎石桩格栅强度设计初探

    Institute of Scientific and Technical Information of China (English)

    唐承铁; 刘猛

    2012-01-01

    分析了加筋碎石桩复合地基的承载机理,探讨了加筋碎石桩复合地基的2种主要破坏模式,破坏模式1由格栅套筒抗拉强度控制,破坏模式2由非加筋段桩侧土强度控制.采用极限平衡理论分别导出了两种不同的破坏模式下加筋碎石桩单桩极限承载力计算公式.基于2种破坏模式下的承载力计算公式,在加筋深度一定的情况下给出了格栅合理设计强度解析解.最后,运用本文方法对某工程实例进行计算,计算结果与实测数据吻合较好.%The bearing mechanism of geosynthetic-encased stone columns was analyzed and two primary kinds of failure modes was investigated. Failure mode 1 is mainly controlled by the strength of geogrid sleeve, and failure mode 2 is controlled by the strength of the soil along the no-reinforced section. Based on the two failure modes, the method of the limit equilibrium is employed to deduce the formulas of the ultimate bearing capacity by which, the expression of the optimal design strength of the geogrid is presented in this paper. At last, when the method was used to analyze the practical project, its feasibility was proved by the reasonable agreement between the calculated and the measured values.

  10. Experimental study of soil arching of geogrid-reinforced and pile-supported widening embankment%桩-网加固拓宽路堤土拱效应试验研究

    Institute of Scientific and Technical Information of China (English)

    吕伟华; 缪林昌; 王非; 蔡海粟; 张成相

    2013-01-01

    Soil arching is very important for analyzing the stress state of existing and widening embankment and differential settlement between piles (caps) and subsoil. In this paper, the behavior of soil arching is analyzed for a widening embankment which is supported by rigid piles with caps and reinforced by geogrid. Based on the test site of the widening expressway project, earth pressures on caps and subsoil at the bottom and at different depths to fill surface are investigated; and tensile strains of the geogrid are monitored too. Then stress concentration ratios and soil arching ratios are analyzed and compared with several current design methods, including the Guido method, the BS8006 method, the Kempfert method and the Low method. Results show that, a two-dimensional plane soil arching fill load distribution on caps and subsoil within a critical arch height which is deduced to be 2.0 m owing a ratio of 1.4 the pile clear spacing, and is consistent with BS8006. The Guido and BS8006 methods were too conservative on assessing tensile strain of geogrid; Except for the Guido method, all rest presented design methods underestimated the resistance from the compressible subsoil. So, further study and a better understanding of soil arching should be developed.%  采用桩-网加固拓宽路堤时,土拱效应对于分析新老路堤应力分布和差异沉降有至关重要的作用。依托某高速公路路堤拓宽项目对土拱效应进行研究,对试验段新路堤填筑过程及运营时基底桩及桩间土不同位置处土压力、加筋层拉应变进行监测,得到二维平面土拱效应的变化规律,并利用已有土拱效应计算方法对现场实测结果进行对比验证。结果表明,平面土拱作用范围在一定高度范围内,试验段约为2.0 m,即拱高、拱跨之比约为1.4,与英国规范 BS8006[1]相近;按 Guido 法[2]与 BS8006法[3]进行土工格栅的设计均过于保守,除 Guido 法以外,几种方

  11. 循环荷载特征对筋土界面剪切特性的影响试验%Experiment of Influence of Cyclic Load Characteristics on Shear Properties of Geogrid-soil Interface

    Institute of Scientific and Technical Information of China (English)

    徐超; 石志龙

    2011-01-01

    Using large-scale interfacial shear apparatus, a series of direct shear tests between geogrid and sand were performed under cyclic load. The influence of normal cyclic load characteristic on shear property of geogrid-quartz sand interface was studied. Cyclic load waveforms were cosine wave, triangle wave, square wave, the frequencies were 0.01, 0.05, 0.1,0. 5 Hz respectively, and amplitudes were 25, 50, 75, 100 kPa in the tests. The test results show that the variational rule of the interface shear stress is controlled by the waveform of normal cyclic load, while the waveform has little influence on the peak shear stress. The interface shear stress is dramatically influenced by frequency and amplitude, the peak shear stress decreases with the increasing of the frequency and increases with increasing of amplitude. The volume strain of sand during the interface shearing progress is obviously affected by frequency and amplitude. The sand volume strain experiences a transition from dilatation to compression with the increase of frequency and amplitude.%采用大型结构面剪切仪进行了循环荷栽作用下土工格栅与砂土的直剪试验,研究了法向循环荷栽特征对土工格栅与石英砂界面剪切特性的影响.循环荷栽的波形取余弦波、三角波、方形波3种,频率分别为0.01、0.05、0.1、0.5 Hz,振幅选择25、50、75、100 kPa四种.分析结果表明:法向循环荷载波形控制了剪应力的变化规律,但对界面的峰值剪应力影响不大;频率和振幅对界面剪应力有显著的影响,峰值剪应力随频率的增大而减小,随振幅的增大而增大;频率和振幅对砂土体积应变的影响明显,随着频率和振幅的增加,石英砂的体积应变由剪胀向剪缩过渡.

  12. 现浇X形桩桩承式加筋路堤三维有限元分析%Three-dimensional finite element analysis of geogrid-reinforced embankment supported by X-section cast-in-place piles

    Institute of Scientific and Technical Information of China (English)

    陈力恺; 孔纲强; 刘汉龙; 金辉

    2013-01-01

    Geogrid-reinforced and pile-supported expressway embankment has been widely applied to soft ground improvement;but its bearing and deformation mechanism has not been deeply understood. Combining with the Fourth Yangtze River Bridge’s north-line soft ground reinforced project in Nanjing, the numerical method is used to analyze the variations of settlement and stress of pile and soil, pile axial force and excess pore water stress. The results show that road embankment load is mainly borne by piles as a result of the soil arching effect. The soil pressures of pile and soil increase with the development of embankment load firstly;and then the pressure of pile continue to increase while the pressure of soil decreases in the consolidation process of soft soil. The pile axial force increases quickly during the process of filling. Negative skin friction develops along most part of X-section cast-in-place pile shaft;and the neutral point ascends firstly;with the consolidation of soil, the depth of the neutral point becomes deeper;then the neutral point position is unaltered at the end of soil consolidation.%桩承式加筋路堤在高速公路软基处理中得到了广泛应用,但目前对其承载变形机制还缺乏深刻认识。结合南京长江第四大桥北接线段软基加固工程,基于数值方法对现浇 X 形桩桩承式加筋路堤中桩土沉降、桩土应力、桩身轴力及超静孔隙水压力的发展变化规律进行了分析。研究结果表明,受土拱效应影响,路堤填筑荷载主要由桩体承担,桩及桩间土土压力在路堤填筑过程中均逐渐增大,在软基固结过程中,桩顶土压力继续增大而桩间土土压力逐渐减小,最终趋于各自的稳定值;路堤填筑过程中桩身轴力增长较快,现浇X形桩桩身上部较大部分区段存在负摩阻力,桩身中性点位置经历了先逐渐上移、而后向下移动,最终趋于稳定的过程。

  13. Full-Scale Accelerated Testing of Multi-axial Geogrid Stabilized Flexible Pavements

    Science.gov (United States)

    2017-06-01

    The inclusion of geosynthetics in pavement structures has been utilized as a means of reducing costs and/or extending pavement service life. These... labor and equipment requirements. As new geosynthetic products are developed, full-scale performance data are needed to provide quantifiable benefits to

  14. Construction and Instrumentation of Full-Scale Geogrid Reinforced Pavement Test Sections

    Science.gov (United States)

    2008-04-01

    Improvement of Flexible Pavements Using Geosynthetics for Base Course Reinforcements ii ERDC/CRREL TR-08-6 Abstract: A study is being conducted on full...years of geosynthetic -reinforced base research provided by Perkins and Ismeik (1997), Vischer (2003), and Perkins and Cortez (2005). In one study...Administration (FHWA), pooled-fund study, TPF-5(010), entitled Structural Improvement of Flexible Pavements Using Geosynthetics for Base Course

  15. 土工格栅加筋软土路堤的有限元分析%Finite Element Analysis of Soft Soil Subgrade Reinforced by Geogrids

    Institute of Scientific and Technical Information of China (English)

    秦道标

    2011-01-01

    The calculation method of impacting force is essential for the security of bridges. Firstly, the formulas of impacting force among the design specifications of bridges are compared? Then the method based on numerical analysis is put forward. The Newmark-β method is used to work out the kinematics equation of vehicle-bridge coupled vibration, and the dynamic response of bridges is analyzed by Ansys. Finally, the impacting force is work out. Numerical analysis demonstrates that, the differences among numerical results of the formulas of impacting force are remarked, and the calculation values which only takes spans or fundamental frequency into account are unaccurate; the reseacher suggests that it would be more feasible to modify the formulas of impacting force using more correction coefficients.%在考虑软土地基的固结和土体的非线性应力应变关系的基础上,利用有限元的数值方法对加筋路堤的受力性状和破坏机理进行了分析.分析结果表明,加筋可以减少路堤的沉降,以及侧向位移,并能增加路堤的稳定性.研究成果对软土地基的加筋处理有一定的指导意义.

  16. Experimental study on soil moisture content of geogrid-reinforced clay under freezing-thawing cycle%冻融循环下格栅加筋粘土土体含水率试验研究

    Institute of Scientific and Technical Information of China (English)

    赵荣飞; 宓永宁; 姜广田; 金丹; 高微

    2012-01-01

    通过一系列室内含水率测试试验,研究了格栅加筋粘土在多次冻融循环条件下土体含水率的变动情况,探讨了填料压实度,加筋层数和初始含水率对冻融后土体含水率变动的影响规律.结果表明,压实度对土体ωi影响最大,低压实度时,△ω1为正值,高压实度时,△ω1为负值;加筋层数次之,ω1值随加筋层数增加而减小,在压实度高的土体中尤为显著;初始含水率影响最弱,仅在土体压实度较低时,较大的初始含水率会引起较大的△ω1值.%Through a series of lab-tests on moisture content of soil, the change of the moisture content of the grid-reinforced clay under freezing-thawing cycle is studied herein, and then the law of the impact from the compaction degree, the reinforcement layers and the initial moisture content of the soil on the moisture content of the soil under freezing-thawing cycles are discussed. The result shows that the compaction degree has the greatest impact on the soil body ωi, i. e. △ω1 is positive when the compaction degree is low and △ω1, is negative when the compaction degree is high; meanwhile, the number of the reinforcement layers only has a secondary impact on the soli body, i. e. the value of ω1, is decreased along with the increase of the number of the reinforcement layers, while it is significant in the highly compacted soil; moreover, the impact from the initial moisture content is much less and the greater value of △ω1 is to be only arisen from a greater initial moisture content when the compaction degree of soil is low.

  17. 加筋土挡墙变形及筋材受力特征数值试验研究%Numerical experiment studies on deformation and geo-grid force of reinforced earth retaining wall

    Institute of Scientific and Technical Information of China (English)

    万健

    2015-01-01

    Reinforced soil retaining wall is a kind of effective to solve the problem of high fill embankment and slope measures.In this paper, combined with a highway reinforced soil retaining wall project as the research background, with the aid of numerical analysis method and the deformation characteristics of the retaining wal and data col ected in-situ reinforcement material mechanical properties are studied, the analysis results show that the lower part of the retaining wall reinforcement material earth pressure value is the upper reinforcement material location, soil pressure maximum position from the retaining wal (0.3~0.4) H location;Reinforced materials on the tensile stress distribution and the size of the reinforcement materials stress, along the direction of reinforcement material in 0~1m within the scope of the approximate uniform distribution, exponential distribution outside the 1.0m;Maximum tensile strain values near the wall, along the reinforcement length direction tensile strain nonlinear decreasing; Reinforced retaining wall horizontal deformation along the depth are "fat bel y" shape distribution, the maximum horizontal deformation occurred to about one-third of the wall height, the size is about 16.5mm. Wall had a greater influence on the load on retaining wal and soil deformation;suggest the wal load take 30kpa as load limit of reinforced soil retaining wall. Research results can provide reference for design and construction of reinforced soil retaining wall structure.%加筋土挡墙是一种解决高填方路堤及边坡等问题的有效措施。本文结合某公路加筋土挡墙工程为研究背景,借助数值分析方法和现场实测数据对加筋土挡墙变形特性及筋材受力特性进行了研究。分析结果表明:挡墙下部筋材位置土压力值较上层筋材位置大,土压力最大值位置在距挡墙(0.3~0.4)倍的墙高位置处;筋材上的拉应力分布与筋材受力大小有关,沿筋材方向在0~1m范围内近似呈均匀分布,在1.0m以外呈指数型分布;在面墙附近拉应变值最大,沿筋长方向拉应变非线性减小;加筋挡墙水平变形曲线沿深度呈“胖肚”形分布,最大水平变形出现在约1/3墙高处,大小约为16.5mm;墙顶荷载对挡墙及土体变形影响较大,建议墙顶荷载取30kPa作为加筋土挡墙的荷载限值。研究成果可为加筋土挡墙结构设计及施工提供参考意义。

  18. Research on Stability of High Liquid Limit Soil Embankment Reinforced with Geogrid%土工格栅加筋高液限土路堤的稳定性研究

    Institute of Scientific and Technical Information of China (English)

    陈兴专; 洪宝宁; 刘鑫

    2013-01-01

    The constitutive model of soil is established by Plaxis,and the control variable method is used to analyze the stability factors,such as the role of tendon-soil interface,reinforced pitch,reinforced position and so on .Some useful conclusions are drawed:the better the soil’s quality and reinforcement stiffness,the better are the reinforcement effect and embankment stability;the stability of bottom reinforcement is obviously better than that of the middle and upper;the reinforcement encryption can not effectively improve the stability of embankment .Through the field tests of a highway in Guangdong,it is proved that the optimized design could reduce the surface subsidence and deep horizontal displacement effectively,and also improve the stability of embankment .%运用Plaxis软件,建立土体本构模型,采用控制变量法分析筋土界面作用、加筋间距、加筋位置等对高液限土路堤稳定性的影响.得出结论:土质越好,筋材刚度越大,加筋效果越明显,加筋路堤也越稳定;底部加筋的稳定性明显高于中部和上部加筋;格栅加密不能有效提高加筋路堤的稳定性.通过广东某高速公路现场加筋试验研究,验证了优化的加筋设计能较好降低高液限土路堤的表面沉降和深层水平位移,提高路基的稳定性.

  19. Relationship Between Structure and Viscoelastic Properties of Geosynthetics

    Directory of Open Access Journals (Sweden)

    Loginova Irina

    2016-01-01

    Full Text Available In this work, a study on viscoelastic properties of geosynthetic materials used in civil engineering is presented. Six samples of geofabrics and geogrids with different structures including woven geotextile fabric, nonwoven geotextile fabrics, warp-knitted geogrids and extruded geogrid were investigated. The tensile properties of geosynthetics including tensile strength, strain at maximum load and tensile load at specified strain have been determined. The creep and relaxation tests were carried out. The structure type was found to significantly affect the viscoelastic properties of the geosynthetics materials. In the article some results of numerous conducted tests are presented, analyzed and may be used to preselection of geosynthetics materials.

  20. The Behavior of Foundation Soil with and without Geosyntethic Reinforcement

    Directory of Open Access Journals (Sweden)

    Felicia NICULESCU-ENACHE

    2013-07-01

    Full Text Available This paper presents the computed diagrams showing the soil behavior in two alternative calculation hypotheses (with/without geogrid reinforcement will be compared, so that the positive effect of two geogrid layers used for reinforcement is revealed. The diagrams show that the use of reinforcement layers contributes to a more uniform distribution of loads and to the decrease of the pressure, thus increasing the bearing capacity of the soil.

  1. Laboratory Measurement of Pullout Resistance of Geotextiles Against Cohesive Soils

    Science.gov (United States)

    1992-06-01

    with three geosynthetics (two geotextiles and a geogrid) and two normal loads. However, as geogrids were not being used in the reinforced levee...and the rate of shear deformation at interface of soil and rubber 49. Even though slightly different geosynthetics were used, the soils and molding...Testing of Geo- grids," Proceedings Geosynthetics 󈨛 Conference, New Orleans, La., Febru- ary 24-25, Industrial Fabrics Association International, St

  2. AN FE ANALYSIS OF REINFORCED SUBGRADE UNDER AUTOMOBILE LOADING

    Institute of Scientific and Technical Information of China (English)

    YAN Shuwang; ZHANG Xinqiang; LIU Run

    2004-01-01

    An FE analysis procedure was presented to predict the behavior of soil-geogrid interaction under automobile loading. The dynamic interactions between the transverse bars, the longitudinal ribs and the soil were simulated by a system consisting of nonlinear springs, dashpots and masses, to study the deformation properties of the reinforced soil. The equivalent stiffness and damping ratios could be determined with the shaking table. The dynamic responses of a reinforced subgrade were analyzed with the 3D finite element approach. This approach is programmed and applied to analyze the soil-geogrid interaction under dynamic loading. The comparative analysis of the response of the reinforced subgrade and that of the subgrade without reinforcement shows that the geogrid placed at the bottom of the base layer may effectively reduce the accumulative plastic deformation due to the cyclic automobile loading.

  3. Eccentrically Loaded Small Scale Ring Footing on Resting on Cohesionless Soil

    Directory of Open Access Journals (Sweden)

    Dr. A. I. Dhatrak

    2016-08-01

    Full Text Available A number of works have been carried out for the evaluation of a ultimate bearing capacity of shallow foundation, supported by geogrid reinforced sand and subjected to centric load. Few experimental studies have been made on the calculation of bearing capacity of shallow foundation on geogrid-reinforced sand under eccentric loading. However these studies are for strip footings. This paper presents the behavior of ring footing under eccentric loading on sand. The model tests have been conducted using ring footing with ring radii ratio (Di/Do = 0.4, 0.6, 0.8 for varring eccentricity ratio. Parametric studies have been made to find the impact of eccentricity ratio, ring radii ratio and geogrid reinforcement on bearing capacity of the foundation.

  4. Effect of Bearing Capacity of Strip Footing on Reinforced Double Layer Soil System with Fly ash Stabilized Clayey Soil

    Directory of Open Access Journals (Sweden)

    Love Sharma

    2015-08-01

    Full Text Available This research was performed to investigate the effect of bearing capacity of strip footing on geogrid reinforced sand overlay on stabilized expansive soil (i.e. double layer soil system and check the different parameters contributing to their performance using laboratory model tank tests. The parameters investigated in this study include H/B (thickness of top sandy layer to width of footing u/B (location of the 1st layer of reinforcement to width of footing, h/B (vertical spacing between consecutive geogrid layers to width of footing, b/B (length of the geogrid layer to width of footing. The effect of different H/B ratios and geogrid reinforcement N values on the bearing capacity ration (BCR and settlement reduction ratio (SRR were also investigated. The results show that bearing capacity increases significantly with increasing the H/B ratio as well as number of geogrid layers. The bearing capacity for the soil increases with an average of 12.35% using H/B equal to0.5 and the bearing capacity increases with an average of 35.76%, 75.56% & 230.83% while using H/B equal to 1.0, 1.5 & 2.0. It also found that the use of sandy layers over flyash mixed clayey soil has a considerable effect on the bearing capacity characteristics and the use of geogrid layers in the granular overlay has remarkable effect on Bearing capacity ratio (BCR & Settlement reduction ratio (SRR.

  5. DYNAMIC BEHAVIOR OF BURIED BEND WITH THRUST RESTRAINT IN LIQUEFYING GROUND

    Science.gov (United States)

    Kawabata, Toshinori; Sawada, Yutaka; Mohri, Yoshiyuki; Ling, Hoe I.

    In this study, a shaking table test was carried out in order to discuss the dynamic behavior for the bend of pressure pipeline with a concrete block and thrust restraints using geogrids or gravels in liquefying ground. As a result, it was revealed that the concrete block was largely moved and the relative displacement between the bend and the adjacent pipe became large. On the other hand, it was proved that geogrids and gravels were very effective for the lateral resistance in liquefying ground. In addition, the relative displacement was small because of the same difference between the bend and the adjacent pipe.

  6. In-depth improvement of soil at the base of roads on taliks

    Institute of Scientific and Technical Information of China (English)

    Alexey Y Burukin; Svyatoslav Ya Lutskiy; Konstantin N Khripkov

    2015-01-01

    The article presents a new technological solution to improve the safety of embankment bases on taliks during construction periods. The use of geotextile-sleeved sand columns and geogrids on low-temperature permafrost is investigated. The correlations between mechanical and temperature processes under this in-depth base improvement method are calculated.

  7. Folosirea pământului armat la fundaţii pe terenuri slabe

    Directory of Open Access Journals (Sweden)

    Felicia Enache Niculescu

    2011-06-01

    Full Text Available The geosynthetics term is generally regarded to encompass eight main product categories: geotextiles, geogrids, geonets, geomembranes, geocomposites, geocells and combinations of materiales. These synthetic polymeric can be fabricated from hight resistences, deformation needetand a good adherence with earth confinement.

  8. Case studies of high-sensitivity monitoring of natural and engineered slopes

    Directory of Open Access Journals (Sweden)

    Werner Lienhart

    2015-08-01

    Full Text Available High-sensitivity monitoring solutions are crucial for early warning systems of earth structures. In this paper, we discuss the design and implementation of such systems for natural and engineered slopes using two case studies. At the Gradenbach Observatory, one key element of the monitoring system is a large fiber optic strain rosette embedded in the slope. We demonstrate that the strain rosette can depict landslide deformations much earlier than geodetic sensors like GPS or total stations and is therefore well suitable for an early warning system. In a second application we report the construction of a reinforced earth structure using geogrids. A distributed fiber optic measurement system was installed to measure the current operating grade of the geogrids within the earth structure. About 2 km of Brillouin sensing cables were installed in the project area. It is demonstrated that the developed monitoring system is well suited for assessing the current state of health of reinforced earth structures.

  9. Assessment of reinforced slopes instability in view of semi-analytical methods

    DEFF Research Database (Denmark)

    Tzavara, I.; Tsompanakis, Y.; Zania, Varvara

    The stabilization of natural or man-made earth slopes is usually achieved via proper reinforcement, which usually comprises of geosynthetic geogrids. On the other hand, earthquakes impose in such geostructures dynamic stresses, which may be excessive and can lead to accumulation of slip displacem......The stabilization of natural or man-made earth slopes is usually achieved via proper reinforcement, which usually comprises of geosynthetic geogrids. On the other hand, earthquakes impose in such geostructures dynamic stresses, which may be excessive and can lead to accumulation of slip...... displacements along discrete failure surfaces. Under this perspective, in the dynamic response of reinforced soil structures and the potential of the geosynthetics to prevent the seismic induced instabilities are being assessed the current study. The method employed is based on a modified procedure...

  10. Modeling of geosynthetic reinforced capping systems

    Energy Technology Data Exchange (ETDEWEB)

    Viswanadham, B.V.S.; Koenig, D.; Jessberger, H.L. [Univ. of Bochum (Germany)

    1997-12-31

    The investigation deals with the influence of a geosynthetic reinforcement on the deformation behavior and sealing efficiency of the reinforced mineral sealing layer at the onset of non-uniform settlements. The research program is mainly concentrated in studying the influence of reinforcement inclusion in restraining cracks and crack propagation due to soil-geosynthetic bond efficiency. Centrifuge model tests are conducted in the 500 gt capacity balanced beam Bochum geotechnical Centrifuge (Z1) simulating a differential deformation of a mineral sealing layer of a landfill with the help of trap-door arrangement. By comparing the performance of the deformed mineral sealing layer with and without geogrid, the reinforcement ability of the geogrid in controlling the crack propagation and permeability of the mineral swing layer is evaluated.

  11. Case studies of high-sensitivity monitoring of natural and engineered slopes

    Institute of Scientific and Technical Information of China (English)

    Werner Lienhart

    2015-01-01

    High-sensitivity monitoring solutions are crucial for early warning systems of earth structures. In this paper, we discuss the design and implementation of such systems for natural and engineered slopes using two case studies. At the Gradenbach Observatory, one key element of the monitoring system is a large fiber optic strain rosette embedded in the slope. We demonstrate that the strain rosette can depict landslide deformations much earlier than geodetic sensors like GPS or total stations and is therefore well suitable for an early warning system. In a second application we report the construction of a reinforced earth structure using geogrids. A distributed fiber optic measurement system was installed to measure the current operating grade of the geogrids within the earth structure. About 2 km of Brillouin sensing cables were installed in the project area. It is demonstrated that the developed monitoring system is well suited for assessing the current state of health of reinforced earth structures.

  12. MULTI-RESOLUTION SEAMLESS IMAGE DATABASE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper presents the basic concepts and principles,data structure and high efficient spatial index for multi-resolution image database.The database is characterized by arrangement of multi-resource image data and seamless mosaic,distribution-based storage and management,integration with other spatial database software such as GeoStar and GeoGrid developed by Wuhan Technical University of Surveying and Mapping.

  13. 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.

  14. Slope Stability Estimation of the Kościuszko Mound in Cracow

    Directory of Open Access Journals (Sweden)

    Wrana Bogumił

    2015-06-01

    Full Text Available In the paper, the slope stability problem of the Kościuszko Mound in Cracow, Poland is considered. The slope stability analysis was performed using Plaxis FEM program. The outer surface of the mound has complex geometry. The slope of the cone is not uniform in all directions, on the surface of the cone are pedestrian paths. Due to its complicated geometry it was impossible to do computing by Plaxis input pre-procesor. The initial element mesh was generated using Autodesk Autocad 3D and next it was updated by Plaxis program. The soil parameters were adopted in accordance with the detailed geological soil testing performed in 2012. Calculating model includes geogrids. The upper part was covered by MacMat geogrid, while the lower part of the Mound was reinforced using Terramesh Matt geogrid. The slope analysis was performed by successives reduction of φ /c parameters. The total multiplayer ΣMsf is used to define the value of the soil strength parameters. The article presents the results of slope stability before and after the rainfall during 33 days of precipitation in flood of 2010.

  15. Behaviour of Single Pile in Reinforced Slope Subjected to Inclined Load

    Directory of Open Access Journals (Sweden)

    Dr. A. I. Dhatrak

    2016-09-01

    Full Text Available Deep foundations, including driven piles, are used to support vertical loads of structures and lateral forces. Typical structures subjected to lateral loads include bridge abutments, transmission tower, sand offshore platforms. Traffic, wind, wave, and seismic forces are common types of lateral loads subjected to pile foundations. The present work is focused on understanding the lateral load capacity of vertical piles located near crest of the slope and subjected to the lateral and inclined loads. The experimental investigation was carried out to study the effect of reinforcing an earth slope on the inclined loading behavior of a single vertical pile located near the slope. Layers of geogrid were used to reinforce a sandy slope of 1V:2H. The parametric studies were performed by varying the length of pile(L, angle of inclination of load (θ, number of geogrid reinforcement (Nr and crest distance. It was observed that the lateral load capacity of pile depends upon these parameters. The lateral load capacity of pile increases with increase in inclination of load, length of pile(L, number of geogrid reinforcement (Nr and crest distance.

  16. An assessment of the geometry effect of geosynthetics for base course reinforcements

    Directory of Open Access Journals (Sweden)

    Xiaoming Yang, Ph.D.

    2012-09-01

    Full Text Available Geosynthetic-reinforced base course is potentially a cost-effective solution for flexible pavement construction. With the recent advance in the mechanistic-empirical pavement design in the United States, there is a need to develop the next generation design method for geosynthetic-reinforced bases in flexible pavements. To develop such a design method requires an improved understanding about the mechanistic behavior, especially the in-plane elastic behavior, of geosynthetics. In this paper, the geometry effect of geosynthetics was discussed. The author first reviewed recent experimental and numerical studies. Analytical equations based on cellular material mechanics were presented for determining the in-plane elastic properties of geosynthetics. The analytical equations were used to evaluate a few geosynthetics with typical geometries. The results showed that, with the same polymeric material and typical product geometries, the geocell has a better confinement effect than geogrids, and the triaxial geogrid with a triangular aperture has a better confinement effect than the biaxial geogrid with a rectangular aperture. It was also demonstrated that the traditional uniaxial tensile modulus may be a poor indicator of the effectiveness of geosynthetics for base course reinforcements.

  17. 柔性加筋土复合体力学性能试验%Experimental study of mechanical properties of flexible geosynthetic-reinforced soil complex

    Institute of Scientific and Technical Information of China (English)

    胡幼常; 童金田; 刘胜军; 张文明

    2012-01-01

    In order to study the mechanical properties of flexible geosynthetic-reinforced soil complex,a series of unconfined compression tests were conducted in laboratory.The test samples were made up of sand reinforced respectively with nonwoven geotextile,geogrid,both geotextile and fiber,or both geogrid and fiber.Each sample varied in either the number of reinforcement inclusions or the density of sand.Based on the analysis of the test results,some conclusions are drawn as follows.1) There is an appropriate match among the geotextile strength,the reinforcement spacing and the sand density.The samples making according to such match have not only high compressive strengths but also large failure compressive strains.2) Sand reinforced with both geotextile and fiber has a higher compressive strength than that of one reinforced only by geotextile at the same conditions;but only a little difference between them while both the sand has a relatively low density and the reinforcement spacing is small.3) While the compressive strain is larger,the compressive strength of the geogrid-reinforced sand is much lower than that of geotextile-reinforced sand,which is perhaps due to the large difference between the geogrid and the sand in tensile stiffness resulting in sliding at the geogrid-soil interface.4) Compared with the geogrid-reinforced sand,the sample reinforced with both geogrid and fiber has a higher compressive strength at low compressive strain and a larger failure compressive strain due to the fiber inclusions.%为了研究柔性加筋土复合体的基本力学特性,分别对无纺土工布加筋砂、土工格栅加筋砂、"土工布+纤维"综合加筋砂和"土工格栅+纤维"综合加筋砂制作的多组试样完成了一系列组合工况下的无侧限抗压试验.得到以下主要结论:1)土工布的强度和加筋层间距应与砂的密度相匹配,此时,两者协同工作性最好,加筋砂土极限强度高,破坏应变大;2)相同情

  18. Tensile mechanical behaviors of reinforcements and model analysis%加筋土筋材拉伸力学特性与模型分析

    Institute of Scientific and Technical Information of China (English)

    林宇亮; 杨果林; 刘冬

    2011-01-01

    In order to study tensile mechanical behaviors of reinforcements, air tensile tests were carried out on MAC geogrid, 70RE and 80RE geogrid, gabion wire, gabion meshes of different dimensions and mesh-types. Main mechanical indexes of these reinforcements were obtained, and discussions were made on tension distribution along reinforcements and calculating formula for unit elongation of gabion mesh. In addition, standard linear three-element model, nonlinear three-element model and Kawabata improved model were taken in for tensile curves simulation. The results show that MAC geogrid shows high strength characteristic. Most of ribs of 70RE geogrid or 80RJE geogrid rupture simultaneously. Gabion wire yields at low stain. Tensile curve of gabion mesh shows zigzag shape, and the PVC covered-layer has no effect on its tensile strength. Tensile load can distribute along gabion mesh quite uniformly, and there will not be obvious stress concentration. Unit elongation of gabion meshes are determined by hexagonal shape, sectional area of gabion wire, secant deformation modulus, failure strength, and so on. Standard linear model and nonlinear model have good simulation effects on MAC geogrid, gabion wire and gabion mesh, and Kawabata improved model can simulate MAC geogrid quite well.%为研究加筋土筋材拉伸力学特性,选取MAC土工格栅、70RE和80RE土工格栅、格宾金属丝以及不同型号和尺寸的格宾网进行拉伸试验,获得这些筋材的主要力学性能指标,探讨筋材受力集中情况以及格宾网伸长率计算方法.并采用标准线性三元件模型、非线性三元件模型和Kawabata改进模型对各种筋材拉伸曲线进行模拟.研究结果表明:MAC土工格栅表现出显著的高强度特性,70RE和80RE土工格栅的破坏模式为多条筋肋同时崩断;格宾金属丝表现为低应变屈服,格宾网的拉伸曲线呈现出锯齿状,且PVC包裹层对其抗拉强度影响不大;格宾网在拉伸荷载作用下

  19. Numerical Simulation Of The Treatment Of Soil Swelling Using Grid Geocell Columns

    Directory of Open Access Journals (Sweden)

    Fattah Mohammed Y.

    2015-06-01

    Full Text Available In this paper, a method for the treatment of the swelling of expansive soil is numerically simulated. The method is simply based on the embedment of a geogrid (or a geomesh in the soil. The geogrid is extended continuously inside the volume of the soil where the swell is needed to be controlled and orientated towards the direction of the swell. Soils with different swelling potentials are employed: bentonite base-Na and bentonite base-Ca samples in addition to kaolinite mixed with bentonite. A numerical analysis was carried out by the finite element method to study the swelling soil's behavior and investigate the distribution of the stresses and pore water pressures around the geocells beneath the shallow footings. The ABAQUS computer program was used as a finite element tool, and the soil is represented by the modified Drucker-Prager/cap model. The geogrid surrounding the geocell is assumed to be a linear elastic material throughout the analysis. The soil properties used in the modeling were experimentally obtained. It is concluded that the degree of saturation and the matric suction (the negative pore water pressure decrease as the angle of friction of the geocell column material increases due to the activity of the sand fill in the dissipation of the pore water pressure and the acceleration of the drainage through its function as a drain. When the plasticity index and the active depth (the active zone is considered to be equal to the overall depth of the clay model increase, the axial movement (swelling movement and matric suction, as a result of the increase in the axial forces, vary between this maximum value at the top of the layer and the minimum value in the last third of the active depth and then return to a consolidation at the end of the depth layer.

  20. Assessment of reinforced slopes instability in view of semi-analytical methods

    DEFF Research Database (Denmark)

    Tzavara, I.; Tsompanakis, Y.; Zania, Varvara

    The stabilization of natural or man-made earth slopes is usually achieved via proper reinforcement, which usually comprises of geosynthetic geogrids. On the other hand, earthquakes impose in such geostructures dynamic stresses, which may be excessive and can lead to accumulation of slip...... structures. Two approaches were adopted for the analysis of the dynamic stability in order to analyze the conservativeness of the employed method. Firstly, the dynamic response of the sliding soil mass and the development of the seismic accumulated slippage are taken into account simultaneously in a so...

  1. Evolution of the Stability Work from Classic Retaining Walls to Mechanically Stabilized Earth Walls

    Directory of Open Access Journals (Sweden)

    Anghel Stanciu

    2008-01-01

    Full Text Available For the consolidation of soil mass and the construction of the stability works for roads infrastructure it was studied the evolution of these kinds of works from classical retaining walls - common concrete retaining walls, to the utilization in our days of the modern and competitive methods - mechanically stabilized earth walls. Like type of execution the variety of the reinforced soil is given by the utilization of different types of reinforcing inclusions (steel strips, geosynthetics, geogrids or facing (precast concrete panels, dry cast modular blocks, metal sheets and plates, gabions, and wrapped sheets of geosynthetics.

  2. Disturbed state model for sand-geosynthetic interfaces and application to pull-out tests

    Science.gov (United States)

    Pal, Surajit; Wije Wathugala, G.

    1999-12-01

    Successful numerical simulation of geosynthetic-reinforced earth structures depends on selecting proper constitutive models for soils, geosynthetics and soil-geosynthetic interfaces. Many constitutive models are available for modelling soils and geosynthetics. However, constitutive models for soil-geosynthetic interfaces which can capture most of the important characteristics of interface response are not readily available. In this paper, an elasto-plastic constitutive model based on the disturbed state concept (DSC) for geosynthetic-soil interfaces has been presented. The proposed model is capable of capturing most of the important characteristics of interface response, such as dilation, hardening and softening. The behaviour of interfaces under the direct shear test has been predicted by the model. The present model has been implemented in the finite element procedure in association with the thin-layer element. Five pull-out tests with two different geogrids have been simulated numerically using FEM. For the calibration of the constitutive models used in FEM, the standard laboratory tests used are: (1) triaxial tests for the sand, (2) direct shear tests for the interfaces and (3) axial tension tests for the geogrids. The results of the finite element simulations of pull-out tests agree well with the test data. The proposed model can be used for the stress-deformation study of geosynthetic-reinforced embankments through numerical simulation.

  3. Calculation of Bearing Capacity of Geosynthetic-encased Stone Columns%加筋碎石桩承载力计算

    Institute of Scientific and Technical Information of China (English)

    赵明华; 陈庆; 张玲; 马缤辉

    2011-01-01

    The bearing mechanism of composite foundation of geosynthetic-encased stone columns was analyzed, and several kinds of failure mode of the composite foundation were investigated. In different failure modes, according to the limit equilibrium theory, a calculation formula of the ultimate bearing capacity of single geosynthetic-encased stone column was proposed. Failure mode 1 is mainly controlled by the tensile strength of geogrid sleeve, and failure mode 2 is controlled by the pile-lateral friction of geosynthetic-encased stone column and the end bearing capacity of common stone column before the damage of swelling deformation. The example of calculation indicates that the (1) bearing capacity of geosynthetic-encased stone column has significantly improved than that of common stone column; (2) the reinforcing depth of geosynthetic-encased stone column and the tensile strength of geogrid sleeve have a best combination for the most rational using of geogrid to improve the bearing capacity of the stone columa At last, the geosynthetic-encased stone columns were applied to treatment of weak subgrade of expressway.%分析了加筋碎石桩复合地基的承载机理,探讨了加筋碎石桩复合地基的几种破坏模式.在不同的破坏模式下根据极限平衡理论导出了加筋碎石桩单桩极限承载力计算公式,破坏模式1主要由格栅套筒抗拉强度控制,破坏模式2由加筋段桩体侧摩阻力和非加筋段桩体鼓胀破坏前向上提供的端承力共同控制.实例计算表明,加筋碎石桩的承载力比普通碎石桩的承载力有显著提高,且加筋碎石桩的加筋深度与格栅抗拉强度之间有最优组合,最合理地利用加筋格栅提高碎石桩承载力,最后将加筋碎石桩应用到了高速公路软基处治中.

  4. Influence of Repeated Loading and Geosynthetic Reinforcement on Base Course Thickness over Soft Soil

    Directory of Open Access Journals (Sweden)

    Slamet Widodo

    2012-01-01

    Full Text Available Vehicle wheels at surface of pavement will pass through it many times. Pavement or base course over soft soil always needs a reinforcement.  Influence of repeated loading to thickness of base course and base course reinforced by geosynthetic is presented. Several existing methods as Giroud-Han, USA Corps of Engineers and DuPont Typar method respectively to calculate thickness of base course over soft soil using reinforcement material either geotextile or geogrid is presented and the influence of repeated loading will be compared. Results from calculation and analysis indicate that Giroud-Han method gives thickness of base course higher than other methods when CBR values of subgrade at least 2 %.

  5. Performance of Geosynthetic-Reinforced Soils Under Static and Cyclic Loading

    Directory of Open Access Journals (Sweden)

    M. Touahmia

    2017-04-01

    Full Text Available This paper investigates and discusses the composite behavior of geosynthetic reinforced soil mass. It presents the results of a series of large-scale laboratory tests supported by analytical methods to examine the performance of geogrid reinforcement subjected to static and cyclic pullout loading. The testing equipment and procedures used for this investigation are outlined. The results show that geosynthetic reinforcement can mobilize great resistance to static pulling load under high confining pressures. The reinforcement exhibits gradual deformation under cyclic loading showing no sign of imminent pullout failure for all levels of applied loads. In general, the results demonstrate that geosynthetic can be used in situations where loads are non-static, although care will be required in ensuring that appropriate factors of safety are applied to control the resulting deformation. A simplified analytical model for calculating the pulling capacity of geosynthetic reinforcement is proposed.

  6. Strain gage installation and survivability on geosynthetics used in flexible pavements

    Science.gov (United States)

    Brooks, Jeremy A.

    The use of foil type strain gages on geosynthetics is poorly documented. In addition, very few individuals are versed in proper installation techniques or calibration methods. Due to the limited number of knowledgeable technicians there is no information regarding the susceptibility of theses gages to errors in installation by inexperienced installers. Also lacking in the documentation related to the use of foil type strain gages on geosynthetics is the survivability of the gages in field conditions. This research documented procedures for installation, calibration, and survivability used by the project team to instruments a full scale field installation in Marked Tree, AR. This research also addressed sensitivity to installation errors on both geotextile and geogrid. To document the process of gage installation an experienced technician, Mr. Joe Ables, formerly of the UASCE Waterways Experiment Station, was consulted. His techniques were combined with those discovered in related literature and those developed by the research team to develop processes that were adaptable to multiple gage geometries and parent geosynthetics. These processes were described and documented in a step by step manner with accompanying photographs, which should allow virtually anyone with basic electronics knowledge to install these gages properly. Calibration of the various geosynthetic / strain gage combinations was completed using wide width tensile testing on multiple samples of each material. The tensile testing process was documented and analyzed using digital photography to analyze strain on the strain gage itself. Calibration factors for each geosynthtics used in the full scale field testing were developed. In addition, the process was thoroughly documented to allow future researchers to calibrate additional strain gage and geosynthetic combinations. The sensitivity of the strain gages to installation errors was analyzed using wide width tensile testing and digital photography to

  7. TECHNICAL SOLUTIONS TO CREATE ESTHETICAL CIVIL ENGINEERING STRUCTURES USING THE GEOSYNTHETICS MATERIALS

    Directory of Open Access Journals (Sweden)

    Teodor Eugen Man

    2010-01-01

    Full Text Available Geosynthetics is the term used to describe a range of generally polymeric products used to solve some civil engineeringproblems. The term is generally regarded to encompass eight main product categories: geotextiles, geogrids, geonets,geomembranes, geosynthetic clay liners, geofoam, geocells (cellular confinement and geocomposites. The syntheticpolymeric nature of these products makes them suitable for use in the ground where high levels of durability arerequired. Not only because, properly formulated, they can also be used in exposed applications. Geosynthetics areavailable in a wide range of forms and materials, each to suit a slightly different end use. These products have a widerange of applications and are currently used in many civil, geotechnical, transportation, geoenvironmental, hydraulic,and private development applications including roads, airfields, railroads, embankments, retaining structures,reservoirs, canals, dams, erosion control, sediment control, landfill liners, landfill covers, mining, aquaculture andagriculture. The paper presents basic aspects of geotextiles, drainage, geocomposite designissues and technicalsolutions of their use.

  8. Análisis del comportamiento a flexión de muros de adobe reforzados con geomallas

    Directory of Open Access Journals (Sweden)

    Solís, M.

    2015-09-01

    Full Text Available Rammed earth is a widely used building material in many regions of the world. Due to the high seismic risk in those areas, earthen constructions require suitable and efficient reinforcement techniques from a technological and socioeconomic point of view. This paper analyzes the bending behavior of geogrid reinforced adobe walls from an experimental and analytical point of view. The experimental bending moment-curvature relationships are analytically approached. The results show how geogrid reinforcement improves the performance of adobe masonry in terms of strength and ductility. Thus, a better seismic performance is achieved.La tierra cruda constituye el material de construcción más importante en muchas regiones del planeta. Dado el riesgo sísmico existente en la mayor parte de estas regiones, es necesario el desarrollo de técnicas de refuerzo eficaces y adecuadas desde un punto de vista tecnológico y socioeconómico. Este artículo analiza desde un punto experimental y analítico el comportamiento a flexión de muros de adobe reforzados con geomallas. Las leyes momento-curvatura de los muros ensayados son aproximadas mediante una serie de modelos analíticos que permiten analizar el comportamiento del material compuesto adobe-geomalla. Los resultados obtenidos muestran como la geomalla mejora el comportamiento de la mampostería de adobe en términos de resistencia y ductilidad, mejorando así su comportamiento en caso de movimiento sísmico.

  9. Integrating shotcrete walls into the natural landscape by application of 'Green Walls'

    Science.gov (United States)

    Medl, Alexandra; Kikuta, Silvia

    2017-04-01

    Steep slopes resulting from major road infrastructure constructions are increasingly perceived as disagreeable disturbance in the landscape. Thus, a tool to consider landscape aspects and integrate these slopes into the natural environment is required. The challenge is to establish a sustainable vegetation layer despite of adverse circumstances such as inclinations of almost 90⁰, exposed position of slopes near streets and lack of soil and water supply. The objective of this study was to assess the performance of an innovative greening technology for vertical structures (shotcrete wall) in terms of vegetation development on varying plant substrates and geotextiles. The field experiment in Steinach am Brenner, Tyrol, Austria, included testing three plant substrates on basis of nearby rocky excavation material ('Innsbrucker Quarzphyllit', 'Bündnerschiefer' and 'Zentralgneis') combined with compost. Additionally, five geotextiles (geogrid (3x4 mm), geogrid (9x10 mm), coir net, coir mat, geo mat) were applied for evaluation. All test combinations were evaluated regarding vegetation cover and biomass production from 2015 to 2016. Analyses of chemical properties were conducted for all plant substrates. Results showed highest vegetation cover ratio on 'Bündnerschiefer' and 'Innsbrucker Quarzphyllit', which can be explained by the favorable mineral composition (nutrient storage capacity) and chemical properties of compost (lower values of electrical conductivity and C/N ratio). In conclusion, the use of 'Green Walls' filled with 'Bündnerschiefer' or 'Innsbrucker Quarzphyllit' plant substrate in combination with netlike geotextiles proved best, since geo grid and coir net turned out as most successful one year after installation. 'Green Walls' are promising in terms of establishing an optimal vegetation cover on vertical structures and are well suited for integrating shotcrete walls into the landscape. The use of local excavation material for greening purposes can be

  10. Study on Influence of Geotextile and Its Laying Position to Anti-Cracking Performance of Asphalt Mixture%土工材料及其加铺位置对沥青混合料抗裂性能影响研究

    Institute of Scientific and Technical Information of China (English)

    莫石秀; 孔令云

    2016-01-01

    By comparing bending test, cracking test, uniaxial compression test, and fatigue test on sample beams of fiber glass geo - grid, paving polyester filament singeing Geotextile and geo - grid with no paving, this paper studies influence to performance of asphalt mixture by different geotextile material and its laying position. Analysis on test results shows that laying fiber glass geo-grid has obvious influence to rupture strain of asphalt mixture which has greatly improved the stiffness modulus as well as the anti -fatigue performance. As temperature reduces, test samples paved with fiber glass geo-grid has better anti-tensile strength comparing with test sample paved with geo-textile cloths. However, the influence on rupture strain or stiffness modulus was not so obvious.%通过比较玻璃纤维土工格栅、加铺聚酯长丝烧毛土工布以及不加铺土工格栅的试样小梁弯曲试验、劈裂试验、单轴压缩试验、疲劳试验,研究不同种类土工材料及其铺设位置对沥青混合料性能的影响。试验分析表明:铺设玻璃纤维格栅对沥青混合料破坏应变影响显著,对其劲度模量有较大改善,且其疲劳性能也得到明显改善;随着温度降低,加铺玻璃纤维格栅后试件抗拉强度提高幅度明显高于加铺土工布的,但对其破坏应变、劲度模量的影响不是很显著。

  11. 差异沉降条件下黄土拓宽路基协调机制模型试验研究%MODEL EXPERIMENTAL STUDY OF LOESS WIDENED EMBANKMENT COORDINATION MECHANISM UNDER CONDITIONS OF DIFFERENTIAL SETTLEMENT

    Institute of Scientific and Technical Information of China (English)

    翁效林; 马豪豪; 梁东平

    2013-01-01

    Aiming to study the loess area highway widening project,based on the large-scale foundation settlement simulation test platform,a scale test with the geometry similarity ratio of 1∶1 is carried out;and the roadbed internal soil and the reinforcing material deformation monitoring systems is also established to analyze the response mechanism of internal soil and reinforcement of the roadbed constructed under the conditions of old and new foundation differential settlements. The results show that:under the widened embankment load,the roadbed internal soil experiences a constant process of deformation and coordination with the increasing foundation differential settlement. When the differential settlement S reaches to 9 cm,subgrade and pavement layer appear a slight void. Laying the geotextile material on old and new roadbed splicing segment can lead loose soil to form the compaction complex,which can enhance the overall stability and mechanical properties of roadbed soil and easily form the arch effect. Besides,the geogrid can digest the settlement between new and old roadbed in a certain degree,but the effect is limited. The geogrid inside the soil plays a coordination role in the subgrade soil deformation. The reinforcement force is not uniform and the corresponding alternating of tension and compression strain appears. With the increasing foundation differential settlement,strain show a increasing trend as a whole. When the differential settlement S between old and new foundation reaches to 16 cm,tension and compression strain of geogrid tend to be stable. The ultimate amount of geogrid tensile or compression changes only 2 mm,far less than the destruction limit of geogrid.%以黄土地区高速公路拓宽工程为研究背景,借助大型地基沉降模拟试验平台,实现拓宽路基荷载下地基沉降变形的人为模拟,开展几何相似比为1∶1的足尺模型试验,建立路基内部土体及加筋材料变形监测系统,分析新老

  12. 输电线路沙漠地区偏心装配式基础的承载性能研究%RESEARCH ON BEARING CAPACITY OF ECCENTRIC ASSEMBLY FOUNDATION OF TRANSMISSION LINE IN DESERT AREA

    Institute of Scientific and Technical Information of China (English)

    侯鹏翔; 郑卫锋; 李维

    2016-01-01

    On geogrid reinforced aeolian sand ground in Ningxia, a full-scale in-site comparison experiments of the uplift bearing capacity for eccentric assembly foundation were tested under uplift loading and uplift combined with horizontal loadings.Both the site conditions and the load tests were recorded comprehensively, allowing for a thorough evaluation of the loading-displacement behavior.Based on the displacement of top plane of foundaiton and the soil reaction forces, the mechanism of the the eccentric assembly foundation on reinforced aeolian sand ground was obtained.Through taking geogrid reinforcement and eccentric structure measures, the bearing performance of assembly foundation was significantly improved, which could improve its anti-horizontal bearing capacity and did not reduce the uplift performance.The test result provided useful evidence for its practice in transmission line projects in aeolian sand.%在宁夏毛乌素加筋风积沙地基中开展偏心装配式基础在单上拔、上拔与水平力组合工况下的现场对比试验,通过监测其顶部荷载位移曲线、地表竖向位移及基础底板土压力数据,分析偏心装配式基础的抗拔承载机理。试验表明:采用增强地基稳定的加筋和设置基础偏心的结构措施,可显著改善装配式基础的受力性能,在提高其抗水平承载性能的同时不降低其抗拔性能,为沙漠地区输电线路工程中应用装配式基础提供了试验数据。

  13. COMPLEX ANALYSIS IN THE RIVER BASIN OF TOPLIŢA AND TECHNOLOGICAL SOLUTIONS FOR SLOPES STABILIZATION

    Directory of Open Access Journals (Sweden)

    Dănuţ Tanislav

    2010-01-01

    Full Text Available Landslides distribution is differentiated function of various causal factors or conditions (litology, declivity, land use,precipitations. For each factor, it can be depicted some homogeneous areas, with numerical coefficients, in a incresingsuccession (1 – very high; … 5 – very low, using the GIS. The complex arrangement involves the analysis and diagnosisof watershed planning, establishing its vulnerability to the action of natural and anthropogenic factors. New technologiesfor earth reinforcement with other engineering works to stabilize the slopes, are durable works because the chemicalproperties of high density polyethylene, which does not react with any other environmental component (ex. earth geogridreinforcement. New technologies for earth reinforcement executed in complex with other engineering works to stabilizethe slopes, are durable works because the chemical properties of high density polyethylene, which does not react withany other environmental component. Using special technology to stabilize determined substantial time and cost savingscompared to traditional solutions. The landscape of slopes reinforced with geogrids, due to external quality topsoil isclearly superior to the classical solutions of stabilization.

  14. USE OF GEOSYNTHETIC CASINGS IN HYDRAULIC ENGINEERING

    Directory of Open Access Journals (Sweden)

    Piyavskiy Semen Avraamovich

    2012-10-01

    Full Text Available The article covers the use of geosynthetic casings in hydraulic engineering. The authors describe the structure of earth dams that have geosynthetic casings used as the reinforcement of downstream slopes. Results of stability calculations are provided. The authors consider several examples of effective application of advanced geosynthetic materials used in combination with local building materials as structural elements of hydraulic engineering facilities. Their analysis has demonstrated a strong potential and expediency of application of geosynthetic casings in the course of construction and renovation of low-pressure earth dams. The authors have also developed a new structure of an earth dam. The new earth dam has geosynthetic casings used as structural reinforcing elements of the crown and the downstream slope. The dam structure contemplates the overflow of high water. The structural strengths of the proposed solution include a smaller material consumption rate, lower labour intensiveness and cost of the slope reinforcement due to the application of local building materials used to fill the casings, fast and easy depositing of slope reinforcing elements, and high workability of its dismantling for repair purposes. The authors have also completed the analysis of stability of geosynthetic casings of downstream slopes of an earth dam. The analysis has proven high efficiency of a small slope ratio in combination with its anchorage and reinforcement of the downstream toe with the help of high-strength geogrids.

  15. Geosynthetics in geoenvironmental engineering

    Directory of Open Access Journals (Sweden)

    Werner W Müller

    2015-05-01

    Full Text Available Geosynthetics are planar polymeric products, which are used in connection with soil, rock or other soil-like materials to fulfill various functions in geoenvironmental engineering. Geosynthetics are of ever-growing importance in the construction industry. Sealing of waste storage facilities to safely prevent the emission of wastewater, landfill gas and contaminated dust as well as the diffusion of pollutants into the environment and coastal protection against storms and floods and reconstruction after natural disaster are important fields of application. We will give an overview of the various geosynthetic products. Two examples of the material problems related to geosynthetics are discussed in detail: the effect of creep on the long-term performance of geocomposite drains and the numerical simulation of the interaction of soil with geogrids. Both issues are of importance for the use of these products in landfill capping systems. The various functions, which geosynthetics may fulfill in the protection of coastal lines, are illustrated by case studies. The geosynthetic market is evaluated and economical and environmental benefits, as well as environmental side effects related to the use of geosynthetics, are discussed.

  16. Laboratory Performance Testing of Two Types of Geotextiles used in Danube Hydrotechnical Works

    Science.gov (United States)

    Dumitru, F. D.; Moncea, M. A.; Panait, A. M.; Olteanu, M.; Laslo, L.

    2017-06-01

    The products included in the geosynthetic category (geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, geofoam, geocells (cellular confinement) and geocomposites) have multiple civil engineering uses, being effectively used as drains and filters in civil and environmental works. The paper aims to test the performance of the geotextiles used for the ecological restoration of riverbank defences on the Danube River, between Calarasi and Braila. For this purpose, the analysed geosynthetics were subjected to hydrolysis and oxidation degradation in laboratory conditions. To evaluate the effect of the two degradation mechanisms, the specimens were subjected to tensile tests at room temperature. The three analysed parameters were tensile strength, elongation and failure mode. The results showed that the tensile strength values for the samples subjected to oxidation and hydrolysis are lower than the ones corresponding to the reference samples, while the elongation values determined after mechanical testing showed that hydrolysis influences the fibre flexibility. The failure mode of the analysed geotextiles highlighted the tendency of the samples to fail either in the calibrated area or at the grip, indicating that in use the geotextile will break in the strained region.

  17. Geosynthetics in geoenvironmental engineering

    Science.gov (United States)

    Müller, Werner W.; Saathoff, Fokke

    2015-06-01

    Geosynthetics are planar polymeric products, which are used in connection with soil, rock or other soil-like materials to fulfill various functions in geoenvironmental engineering. Geosynthetics are of ever-growing importance in the construction industry. Sealing of waste storage facilities to safely prevent the emission of wastewater, landfill gas and contaminated dust as well as the diffusion of pollutants into the environment and coastal protection against storms and floods and reconstruction after natural disaster are important fields of application. We will give an overview of the various geosynthetic products. Two examples of the material problems related to geosynthetics are discussed in detail: the effect of creep on the long-term performance of geocomposite drains and the numerical simulation of the interaction of soil with geogrids. Both issues are of importance for the use of these products in landfill capping systems. The various functions, which geosynthetics may fulfill in the protection of coastal lines, are illustrated by case studies. The geosynthetic market is evaluated and economical and environmental benefits, as well as environmental side effects related to the use of geosynthetics, are discussed.

  18. State of the art design: A closure system for the largest hazardous waste landfill at the Savannah River Site

    Energy Technology Data Exchange (ETDEWEB)

    Bartlett, S.F.; Serrato, M.G.; McMullin, S.R.

    1992-12-31

    This paper discusses the cover system proposed for a 55-acre, hazardous waste closure of the sanitary landfill at the Savannah River Site, near Aiken, South Carolina. The proposed cover system has been designed to accommodate a significant amount of post-closure settlement while maintaining a permeability of 1 {times} 10{sup {minus}7} cm/s or less throughout its 30-year, regulatory lifetime. A composite cover consisting of a geomembrane (GM) underlain by a geosynthetic clay liner (GCL) was selected because of its extremely low permeability, ability to elongate without tearing, and capacity to ``self-heal`` if punctured. These characteristics will enable the cover system to accommodate differential settlement without cracking or tearing, this providing long-term protection with minimal maintenance. Also, to improve the ability of the cover system to span voids that may develop in the underlying waste, a geogrid has been included in the foundation layer. A gas vent layer has been included to allow for the safe collection and venting of landfill gases.

  19. State of the art design: A closure system for the largest hazardous waste landfill at the Savannah River Site

    Energy Technology Data Exchange (ETDEWEB)

    Bartlett, S.F.; Serrato, M.G.; McMullin, S.R.

    1992-01-01

    This paper discusses the cover system proposed for a 55-acre, hazardous waste closure of the sanitary landfill at the Savannah River Site, near Aiken, South Carolina. The proposed cover system has been designed to accommodate a significant amount of post-closure settlement while maintaining a permeability of 1 [times] 10[sup [minus]7] cm/s or less throughout its 30-year, regulatory lifetime. A composite cover consisting of a geomembrane (GM) underlain by a geosynthetic clay liner (GCL) was selected because of its extremely low permeability, ability to elongate without tearing, and capacity to self-heal'' if punctured. These characteristics will enable the cover system to accommodate differential settlement without cracking or tearing, this providing long-term protection with minimal maintenance. Also, to improve the ability of the cover system to span voids that may develop in the underlying waste, a geogrid has been included in the foundation layer. A gas vent layer has been included to allow for the safe collection and venting of landfill gases.

  20. Design and Application of Packaged Reinforced Soil Retaining Wall in the Subgrade of Nanjing-Qidong Railway%包裹式加筋土挡墙在宁启铁路路基中的设计与应用

    Institute of Scientific and Technical Information of China (English)

    罗琼; 白楷

    2012-01-01

    论述了加筋土挡墙基于极限平衡理论的设计方法,以宁启铁路海安枢纽内L1DK0+184.953~+339.410段工程为例,介绍了土工格栅加筋土挡墙的方案比选、拉筋设计,并对其进行内部稳定性和外部稳定性进行检算,包裹式加筋土挡墙良好的施工效果也证明了设计的可靠性。%The paper discusses the design of reinforced soil retaining wall on the basis of limit equilibrium theory. Taking L1DKO + 184. 935 - + 339. 410 section within Haian junction of Nanjing-Qidong Railway as the example, the comparison of geogrid reinforced retaining wall schemes and its reinforcement design are introduced; and then the internal and external stability of the wall is calculated and checked. The good construction effect of the packaged reinforced soil retaining wall also proves the reliability of the design.

  1. A witness to history : the reclamation of Suncor's Pond 1

    Energy Technology Data Exchange (ETDEWEB)

    Eisner, M.

    2010-09-15

    This article described the reclamation of Suncor Energy's very first oil sands tailings pond at Fort McMurray. What had been a tailings pond for the past 43 years years in now inhabited by animals and hundreds of thousands of trees and shrubs. Covering 220 hectares adjacent to the Athabasca River, Suncor's Pond 1 was part of the first commercial-scale oil sands operation in Canada. After decades in operation, the pond is being closed in a highly regulated environment with a considerable knowledge base of reclamation techniques, well-defined reclamation goals and clear land use targets. The initial design of the Pond 1 tailings storage facility consisted of a 12-metre high retention dyke built over Tar Island. Suncor adopted a 3-phase approach to accelerate reclamation activities. In phase 1, the northern half of the pond began receiving reclamation material in 2007. In phase 2, the southern half of the pond continued to receive tailings while the phase 1 area underwent surface reclamation. Phase 3 consisted of a small area of soft tailings that was mechanically stabilized using geo-grid and tailings sand, and was the last area to undergo surface reclamation. Once the water and fine tailings had been removed, the pond was filled with 30 million tonnes of clean sand in 2009. Topsoil was then placed on the pond so that trees and shrubs could be planted. A series of on-site monitoring systems will allow Suncor to track the site. The total cost of the project was within expectations. In January 2010, Suncor began work in on the 440 hectare Pond 5 which was decommissioned in November 2009. To date, coke roadways have been established on Pond 5 to enable dewatering activities using wick drains. 2 figs.

  2. Electrical resisitivity of mechancially stablized earth wall backfill

    Science.gov (United States)

    Snapp, Michael; Tucker-Kulesza, Stacey; Koehn, Weston

    2017-06-01

    Mechanically stabilized earth (MSE) retaining walls utilized in transportation projects are typically backfilled with coarse aggregate. One of the current testing procedures to select backfill material for construction of MSE walls is the American Association of State Highway and Transportation Officials standard T 288: ;Standard Method of Test for Determining Minimum Laboratory Soil Resistivity.; T 288 is designed to test a soil sample's electrical resistivity which correlates to its corrosive potential. The test is run on soil material passing the No. 10 sieve and believed to be inappropriate for coarse aggregate. Therefore, researchers have proposed new methods to measure the electrical resistivity of coarse aggregate samples in the laboratory. There is a need to verify that the proposed methods yield results representative of the in situ conditions; however, no in situ measurement of the electrical resistivity of MSE wall backfill is established. Electrical resistivity tomography (ERT) provides a two-dimensional (2D) profile of the bulk resistivity of backfill material in situ. The objective of this study was to characterize bulk resistivity of in-place MSE wall backfill aggregate using ERT. Five MSE walls were tested via ERT to determine the bulk resistivity of the backfill. Three of the walls were reinforced with polymeric geogrid, one wall was reinforced with metallic strips, and one wall was a gravity retaining wall with no reinforcement. Variability of the measured resistivity distribution within the backfill may be a result of non-uniform particle sizes, thoroughness of compaction, and the presence of water. A quantitative post processing algorithm was developed to calculate mean bulk resistivity of in-situ backfill. Recommendations of the study were that the ERT data be used to verify proposed testing methods for coarse aggregate that are designed to yield data representative of in situ conditions. A preliminary analysis suggests that ERT may be utilized

  3. Model tests on interaction between soil and geosynthetics subjected to localized subsidence in landfills

    Institute of Scientific and Technical Information of China (English)

    Bin ZHU; Deng GAO; Jun-chao LI; Yun-min CHEN

    2012-01-01

    In a landfill,excessive tensile strains or failure of the liner system due to localized subsidence underneath the geosynthetic liner,is a concern in design and operation of the landfill.The localized subsidence can be commonly withstood by reinforcements such as geogrids.A total of nine model tests were carried out to study the influence of soil arching in overburden sandy soil on the geosynthetics and the interaction between the soil and the geosynthetics.The localized subsidence was modeled by a strip trapdoor under the geosynthetic reinforcements.The reinforcement includes several layers of polyvinylchlorid (PVC) membrane or both PVC membrane and a compacted clay layer.Test results show that the vertical soil pressure acting on the geosynthetics within the subsidence zone is strongly related to the deflection of the geosynthetics.The soil pressure acting on the deflected geosynthetics will decrease to a minimum value with respect to its deflection if the final deflection is large enough,and this minimum value is almost independent of the overburden height.Otherwise,the deflection of geosynthetics cannot result in a full degree of soil arching,and the soil pressure within the subsidence zone increases with the increase of overburden height.Deflections and strains of the geosynthetics obviously decrease with the increase of their tensile stiffness.The presence of a compacted clay layer buffer can therefore reduce both deflections and strains of the geosynthetics.Finally,a composite liner structure is recommended for landfills to withstand the localized subsidences.

  4. Evaluation of oxidative behavior of polyolefin geosynthetics utilizing accelerated aging tests based on temperature and pressure

    Science.gov (United States)

    Li, Mengjia

    Polyolefin geosynthetics are susceptible to oxidation, which eventually leads to the reduction in their engineering properties. In the application of polyolefin geosynthetics, a major issue is an estimate of the materials durability (i.e. service lifetime) under various aging conditions. Antioxidant packages are added to the polyolefin products to extend the induction time, during which antioxidants are gradually depleted and polymer oxidation reactions are prevented. In this PhD study, an improved laboratory accelerating aging method under elevated and high pressure environments was applied to evaluate the combined effect of temperature and pressure on the depletion of the antioxidants and the oxidation of polymers. Four types of commercial polyolefn geosynthetic materials selected for aging tests included HDPE geogrid, polypropylene woven and nonwoven geotextiles. A total of 33 different temperature/pressure aging conditions were used, with the incubation duration up to 24 months. The applied oven temperature ranged from 35°C to 105°C and the partial oxygen pressure ranged from 0.005 MPa to 6.3 MPa. Using the Oxidative Induction Time (OIT) test, the antioxidant depletion, which is correlated to the decrease of the OIT value, was found to follow apparent first-order decay. The OIT data also showed that, the antioxidant depletion rate increased with temperature according to the Arrhenius equation, while under constant temperatures, the rate increased exponentially with the partial pressure of oxygen. A modified Arrhenius model was developed to fit the antioxidant depletion rate as a function of temperature and pressure and to predict the antioxidant lifetime under various field conditions. This study has developed new temperature/pressure incubation aging test method with lifetime prediction models. Using this new technique, the antioxidant lifetime prediction results are close to regular temperature aging data while the aging duration can be reduced considerably

  5. 高填土路堤对既有大跨度桥梁桩基的影响分析与监测%Analysis and Field Monitoring on the Effect of High Earth Embankment on the Existing Large Span Bridge Pile foundations

    Institute of Scientific and Technical Information of China (English)

    宋春雨; 季永兴; 孙磊

    2015-01-01

    哈尔滨市松花江北岸滨江大道工程穿越松花江跨江大桥。为减轻路堤填筑对桥桩的影响,基于垂向二维有限元模型及现场监测,研究了土工格栅加筋、钻孔灌注桩隔离及注浆处理等综合措施的可行性,并分析了路堤填筑过程中地基土及桥桩的变形。结果表明:土体加筋、钻孔灌注桩隔离及注浆处理等综合措施可有效减轻路堤填筑对桥桩的影响;路堤填筑对桥桩的影响主要集中在桥墩桩身的上部,桩身下部影响较小;桩基础附加沉降主要由承台上部填土所致,主动区加固措施对减小桥桩的水平位移效果比较明显。研究同时表明,垂向二维有限元模型因桩基简化为板桩墙,使得地层附加应力全部由桩基承担,被动区土层变形的计算结果偏小,桩基变形计算结果偏大。%Bingjiang Avenue is built along the north bank of Songhua River and runs through the Songpu Bridge in Haerbin city ,the provincial capital of Heilongjiang .The high embankment causes additional stresses in the ground layers affecting on the adjacent piles for the bridge abutment .In this paper ,a 2D FEM model was used to analyze the deforma-tions of soil layers and the performances of bridge piles during the construction .The field monitored data of settlements and lateral displacements were reported and discussed .The synthetic implements including geogrid ,bore piles for stress isolation and compaction grouting were studied for their feasibility on controlling the influences of high embankment on the bridge piles ,as well as the deformation of the foundation and the bridge piles .The results of computations and measure-ments in situ can be summarized as follows :the synthetic implements mentioned above can alleviate the influence of em-bankment construction on the adjacent bridge piles ;high embankment mainly affects on the performance of upper part of the piles ,while the lower parts are

  6. GENESI-DR: Discovery, Access and on-Demand Processing in Federated Repositories

    Science.gov (United States)

    Cossu, Roberto; Pacini, Fabrizio; Parrini, Andrea; Santi, Eliana Li; Fusco, Luigi

    2010-05-01

    -DR operational platform is currently being validated against several applications from different domains, such as: automatic orthorectification of SPOT data; SAR Interferometry; GlobModel results visualization and verification by comparison with satellite observations; ozone estimation from ERS-GOME products and comparison with in-situ LIDAR measures; access to ocean-related heterogeneous data and on-the-fly generated products. The project is adopting, ISO 19115, ISO 19139 and OGC standards for geospatial metadata discovery and processing, is compliant with the basis of INSPIRE Implementing Rules for Metadata and Discovery, and uses the OpenSearch protocol with Geo extensions for data and services discovery. OpenSearch is now considered by OGC a mass-market standard to provide machine accessible search interface to data repositories. GENESI-DR is gaining momentum in the Earth Science community thanks to the active participation to the GEO task force "Data Integration and Analysis Systems" and to the several collaborations with EC projects. It is now extending international cooperation agreements specifically with the NASA (Goddard Earth Sciences Data Information Services), with CEODE (the Center of Earth Observation for Digital Earth of Beijing), with the APN (Asia-Pacific Network), with University of Tokyo (Japanese GeoGrid and Data Integration and Analysis System).

  7. Green technologies in natural and synthetic surfaces use for dumps reclamation

    Science.gov (United States)

    Klimkina, Iryna; Fedotov, Viacheslav; Heilmeier, Hermann

    2016-04-01

    Last 50 years coal dumps reclamation in Ukraine was based on two- or three-layer models. These models use a fertile substratum underneath a black soil (chernozem) layer 0.5 m thick (Model 1) or 0.70-1 m thick (Model 2). Model 3 has 3 layers. The deepest layer is a substrate which is phytotoxic or unfavourable for crop growth (coal-bearing substrates with a high content of pyrite, saline substrates). The second layers acts as a protective shield and consist of loess (0.5 m). The third is the layer of fertile chernozem (0.3-0.8 m). However, due to the situation of a shortage of fertile soils, a lack of nutrient elements in the waste rock, and a moisture deficit with strong rock acidification, it is considered important to develop new non-traditional reclamation methods based on the geo-synthetic materials used in conjunction with sowing lawn grasses or grass seeds inside. The geogrids and biogeotextiles made from natural materials such as hemp, flax, jute, coconut and other plant biopolymer fibers are recommended for bioremediation. The biodegradable carcass of reclamation covering materials stabilises the slopes, effectively restraints the soil particles from leaching and blowing, and prevents wash-out of the plant seeds, as well as protecting them from being eaten by animals. The research object of the presented work was the coal dumps of sulfide rocks in Western Donbass (Ukraine). These rocks are characterized by low level of the maximum hygroscopic moisture (4.3%) and moisture content not available for plant growth (5-6%). Also the rock has an average level of salinity, mainly of the sulphate type. The main goal of the study was to justify the use of some non-traditional materials such as burlap (jute cloth), agricultural fibers (light non-woven material from polypropylene fiber of spun-bond type) and a padding of polyester in the capacity of a geosynthetic substrate as a basis for the mixed grass crop that enable a reduction in the bioremediation costs (in

  8. 包裹式加筋土挡土墙抗震试验分析%Seismic Tests and Analysis of Warped Reinforced Earth-retaining Wall

    Institute of Scientific and Technical Information of China (English)

    李庆海; 王炳锟; 蒋楚生; 段忠臣

    2012-01-01

    Research purposes: According to the engineering features of the Xiangyun Station of Guangtong-Dali Railway, the research was done on the reinforcing mechanism, load bearing, deformation, design methods, computing theory and the failure mode of the wraped reinforced earth-retaining wall under earthquake effect to improve the computing theory and numerical simulation method for the seismic design of the reinforced earth-retaining wall and promote the application of reinforced earth-retaining wall in engineering. Research conclusions; The warped reinforced earth-retaining wall is better than the ordinary earth-retaining wall in seismic property because the wrapped effect can make seismic wave weak during the propagation and amplification of the seismic wave along the wall up. When in 0. 4 g and 0. 616 g , the model produced the evident seismic fall, and cracks happened in the junctions between the wall panel and the reinforced soil and between the reinforced soil and the unreinforced soil. In the peak acceleration, the potential fracture surface of these two kinds of experimental models were distributed in the same position, approximate to 0.45 H vertical line. But in the "Code for Design of Retaining Structure of Railway Subgrade" (TB 10025-2006) , the potential fracture surface is approximate to 0.3 H vertical line and it slants to unsafety. So the reinforcing length should be increased in design. From the theoretical calculation and the analysis results of the internal and external stability of the reinforced earth-retaining wall obtained by the test data calculation, it was seen the coefficient of sliding resistance, the coefficient of capsizing resistance, the coefficient of uplifting resistance of the whole wall and the coefficient of uplifting resistance of the geogrid in various layers obtained by theoretical calculation were larger than the test data calculation. This showed the current code was unsafe and could be properly modified.%研究目的:针对广

  9. Grid enablement of OpenGeospatial Web Services: the G-OWS Working Group

    Science.gov (United States)

    Mazzetti, Paolo

    2010-05-01

    international projects investigated different aspects of this integration, developing demonstrators and Proof-of-Concepts; In this context, "gLite enablement of OpenGeospatial Web Services" (G-OWS) is an initiative started in 2008 by the European CYCLOPS, GENESI-DR, and DORII Projects Consortia in order to collect/coordinate experiences on the enablement of OWS on top of the gLite middleware [GOWS]. Currently G-OWS counts ten member organizations from Europe and beyond, and four European Projects involved. It broadened its scope to the development of Spatial Data and Information Infrastructures (SDI and SII) based on the Grid/Cloud capacity in order to enable Earth Science applications and tools. Its operational objectives are the following: i) to contribute to the OGC-OGF initiative; ii) to release a reference implementation as standard gLite APIs (under the gLite software license); iii) to release a reference model (including procedures and guidelines) for OWS Grid-ification, as far as gLite is concerned; iv) to foster and promote the formation of consortiums for participation to projects/initiatives aimed at building Grid-enabled SDIs To achieve this objectives G-OWS bases its activities on two main guiding principles: a) the adoption of a service-oriented architecture based on the information modelling approach, and b) standardization as a means of achieving interoperability (i.e. adoption of standards from ISO TC211, OGC OWS, OGF). In the first year of activity G-OWS has designed a general architectural framework stemming from the FP6 CYCLOPS studies and enriched by the outcomes of other projects and initiatives involved (i.e. FP7 GENESI-DR, FP7 DORII, AIST GeoGrid, etc.). Some proof-of-concepts have been developed to demonstrate the flexibility and scalability of such architectural framework. The G-OWS WG developed implementations of gLite-enabled Web Coverage Service (WCS) and Web Processing Service (WPS), and an implementation of a Shibboleth authentication for g