Sample records for capsizing

  1. Crisis control: Preventing chaos-induced capsizing of a ship (United States)

    Ding, Mingzhou; Ott, Edward; Grebogi, Celso


    Responses of many man-made systems, such as ships or oil-drilling platforms, when subject to irregularly time varying environments, can be described by irregularly driven dynamical systems. Consequently, failures of such systems (e.g., capsize of a ship or collapse of a platform), under increasingly severe environmental conditions, come about when the system state escapes from a destroyed chaotic attractor located in some favorable region of the phase space. In this paper we propose a control strategy, based on a previous method of chaos control, which can prevent such failures from taking place. The key feature of our strategy is the incorporation of prediction of the evolution of the environment. This makes possible effective operation of the control even when the temporal behavior of the environment has substantial irregularity. We illustrate the ideas using ship capsizing as an example.


    Directory of Open Access Journals (Sweden)

    De-wei Pan


    Full Text Available The processes of marine salvage require firstly the uprighting of the capsized ship, essentially bringing the deck to point up. Analysis and computation are the keys for the success in the application of the design schemes. Up to date, there are few researches on calculation methods for uprighting process of capsized ships at China and abroad. Researches about the effect of flooding quantity and the variation of the longitudinal strength during the uprighting process of capsized and damaged ships are even rarer. In this paper, hydromechanical equations to describe the effect of flooding are established and a calculation method for the longitudinal strength is introduced with reference to the hydrostatic theory for ships. Three typical uprighting processes are summarized according to the methods of treatment of damaged compartment. The stability of the inverted ship is calculated and analyzed using the General Hydrostatics software(GHS. Reserve buoyancy, shear forces, bending moments and torques are calculated in nine positions along the ship.

  3. Is ENSO related to 2015 Easter Star Capsized on the Yangtze River of China? (United States)

    Xie, P.


    Natural disasters have profound effects on community security and economic damage of China's Hubei province. In June 1st, 2015, a cruise ship, Easter Star, capsized on Yangtze River in Hubei province with 442 died. What reason gives rise to such strong convection causing ship sunk? Based on the wind disasters of Hubei province happened in 1963-2015, this study analyzes their features bytime-series regression, and correlates them to global El Niño/Southern Oscillation (ENSO) events. The compared results demonstrated that the wind disasters shown an increasing tendency. There are two peaks corresponding to the strongest ENSO peaks during the past 50 years; each peak lasts two-three years. The facts demonstrated an essential linear relation between the ENSO phenomena and wind disasters in Hubei province. 2015 Easter Star capsized happened at current El Niño event in 2014-2015. We also observed that the historical wind disasters appeared in seasonal variation. Over 90% events concentrated in spring and summer; very few events happened in autumn and winter. Moreover, the disasters depend on the geographic conditions. Most disasters concentrated in four zones, named as Xingshan-Baokang, Xuanen, Wufeng-Yichang, Jingzhou-Gongan, in which Xingshan and Changyang are the two most density of zones. Yangtze River provides an air flowing conduct for strong convective winds. It can be concluded that the strong convection causing 2015 Easter Star capsized is related to current global ENSO phenomenon.Keywords: ENSO, wind disaster, time-series regression analysis, Easter Star, Yangtze River, Hubei Province,

  4. Analytical method of capsizing probability in the time domain for ships in the random beam seas

    Institute of Scientific and Technical Information of China (English)

    LIU Liqin; TANG Yougang; LI Hongxia


    The methods for constructing safe basins of ships and predicting their survival probability in random waves were studied.The nonlinear differential equation of the rolling motion of ships in random beam seas was established considering nonlinear damping,nonlinear restoring moment,and random waves.The random rolling differential equation was solved in the time domain by applying the harmonic acceleration method and by synthetically considering the instantaneous state of ships and the narrowband wave energy spectrum.The numerical simulation of random capsizing course was brought forward,the safe basins were constructed for safe navigation,and the survival probabilities of ships were calculated.As an example,the safe basins on the rolling initial value plane were constructed for a 30.27-meter-long fishing vessel according to different initial conditions and random wave parameters.The survival probabilities of the fishing vessel under different significant wave heights were predicted.Thus,the survival probabilities of ships in random seas can be predicted quantitatively by the proposed method.

  5. CAPSIZE: A personal computer program and cross-section library for determining the shielding requirements, size, and capacity of shipping casks subject to various proposed objectives

    International Nuclear Information System (INIS)

    A new interactive program called CAPSIZE has been written for the IBM-PC to rapidly determine the likely impact that proposed design objectives might have on the size and capacity of spent fuel shipping casks designed to meet those objectives. Given the burnup of the spent fuel, its cooling time, the thickness of the internal basket walls, the desired external dose rate, and the nominal weight limit of the loaded cask, the CAPSIZE program will determine the maximum number of PWR fuel assemblies that may be shipped in a lead-, steel-, or uranium-shielded cask meeting those objectives. The necessary neutron and gamma shield thicknesses are determined by the program in such a way as to meet the specified external dose rate while simultaneously minimizing the overall weight of the loaded cask. The one-group cross-section library used in the CAPSIZE program has been distilled from the intermediate results of several hundred 1-D multigroaup discrete ordinates calculations for different types of casks. Neutron and gamma source terms, as well as the decay heat terms, are based on ORIGEN-S analyses of PWR fuel assemblies having exposures of 10, 20, 30, 40, 50, and 60 gigawatt days per metric tonne of initial heavy metal (GWD/MTIHM). In each case, values have been tabulated at 17 different decay times between 120 days and 25 years. Other features of the CAPSIZE program include a steady-state heat transfer calculation which will minimize the size and weight of external cooling fins, if and when such fins are required. Comparisons with previously reported results show that the CAPSIZE program can generally estimate the necessary neutron and gamma shield thicknesses to within 0.16 in. and 0.08 in., respectively. The corresponding cask weights have generally been found to be within 1000 lbs of previously reported results. 13 refs., 20 figs., 54 tabs

  6. 水下爆炸及随机外力下破损舰船的倾覆概率分析%Study of capsizing probability of the damaged warship subjected to underwater explosions and random excitations

    Institute of Scientific and Technical Information of China (English)

    张婧; 施兴华


    The calculation of capsizing probability of damaged warship subjected to underwater explosions and random excitations was discussed.The nonlinear differential equation of ship's roll motion under the conditions of underwater explosions and random excitations was established,in which the effect of underwater explosions and average wind disturbing moment were considered as constant heeling moments. Using the method of extended dimension number, the roll equation was transformed to five dimension Ito stochastic differential equation.Probability density function of rolling angle changed with time was presented based on Ganss-Legendre path integration method,when the random disturbance was reduced to white noise. And the expression of capsizing probability of warship was obtained on the basis of the existent capsizing criterion.An example for calculating the capsizing probability of damaged warship subjected to weapon attack with different blasting charge at different time was given and the effect of blasting charge on capsizing probability was analyzed.The study shows that this method could easily predict rolling capsizing probability of damaged warship subjected to underwater explosions and random excitations quantitatively. It is helpful to further research of capsizing and stability.%探讨了水下爆炸载荷和随机风浪联合作用下破损舰船的运动及其倾覆概率的计算.将爆炸载荷作用及平均风扰动力矩处理为定常横倾力矩,建立了爆炸载荷和随机风浪中舰船运动的非线性微分方程.结合扩维技巧,将横摇方程转化为五维Ito随机微分方程,应用Gauss-Legendre路径积分法给出随机扰动为白噪声时横摇角度的概率密度函数随时间的演变,按照现有的倾覆准则给出预报一定装药量下舰船倾覆概率的表达式.通过算例,计算了破损舰船不同装药量下不同时刻的倾覆概率,分析不同装药量对倾覆概率的影响.研究表明,此方法简便可


    Institute of Scientific and Technical Information of China (English)

    HU YUE


    @@ TO THE POINT: Chinese fund management companies spilled red ink in the first half of 2010 as the stock market turned bearish. The shipbuilding industry regains its lost ground but unsteady seas could capsize hopes for continued success.

  8. Wind estimation around the shipwreck of Oriental Star based on field damage surveys and radar observations


    Meng, Zhiyong; Yao, Dan; Bai, Lanqiang; Zheng, Yongguang; Xue, Ming; Zhang, Xiaoling; Zhao, Kun; Tian, Fuyou; Wang, Mingjun


    Based on observational analyses and on-site ground and aerial damage surveys, this work aims to reveal the weather phenomena—especially the wind situation—when Oriental Star capsized in the Yangtze River on June 1, 2015. Results demonstrate that the cruise ship capsized when it encountered strong winds at speeds of at least 31 m s−1 near the apex of a bow echo embedded in a squall line. As suggested by the fallen trees within a 2-km radius around the wreck location, such strong winds were lik...

  9. Numerical modelling of iceberg calving force responsible for glacial earthquakes (United States)

    Sergeant, Amandine; Yastrebov, Vladislav; Castelnau, Olivier; Mangeney, Anne; Stutzmann, Eleonore; Montagner, Jean-Paul


    Glacial earthquakes is a class of seismic events of magnitude up to 5, occurring primarily in Greenland, in the margins of large marine-terminated glaciers with near-grounded termini. They are caused by calving of cubic-kilometer scale unstable icebergs which penetrate the full-glacier thickness and, driven by the buoyancy forces, capsize against the calving front. These phenomena produce seismic energy including surface waves with dominant energy between 10-150 s of period whose seismogenic source is compatible with the contact force exerted on the terminus by the iceberg while it capsizes. A reverse motion and posterior rebound of the terminus have also been measured and associated with the fluctuation of this contact force. Using a finite element model of iceberg and glacier terminus coupled with simplified fluid-structure interaction model, we simulate calving and capsize of icebergs. Contact and frictional forces are measured on the terminus and compared with laboratory experiments. We also study the influence of geometric factors on the force history, amplitude and duration at the laboratory and field scales. We show first insights into the force and the generated seismic waves exploring different scenarios for iceberg capsizing.

  10. Accidents of surface effect ships and hydrofoil craft

    Energy Technology Data Exchange (ETDEWEB)

    Korotkin, I.M.


    The work describes 200 accidents and disasters of hovercraft and hydrofoil craft of the United States, Great Britain, France, and other fleets which occurred in the 1960s and 1970s as a result of capsizing, storm damage, collisions, fires, explosions, etc. The causes of the accidents, the functioning of various craft systems, and the actions of the crews are examined. Recommendations on the prevention of such accidents are discussed.

  11. Elements of Risk Analysis for Collision and Grounding of a RoRo Passenger Ferry

    DEFF Research Database (Denmark)

    Otto, S.; Pedersen, Preben Terndrup; Samuelidis, M.;


    Newly developed software was applied to study the effects of damages due to collision and grounding. The annual risk of collision and grounding was computed for an example RoRo passenger ferry. Collision frequency was evaluated for a specified route taking into account traffic data. Grounding...... reputation was not considered. It was shown that the main part of the calculated annual risk is caused by capsize of the vessel after severe damage....

  12. The effect of tyre and rider properties on the stability of a bicycle


    Bulsink, V.E.; Doria, A.; Belt, van de, M.; Koopman, H.F.J.M.


    To work towards an advanced model of the bicycle-rider-environment system, an open-loop bicycle-rider model was developed in the commercial multibody dynamics software ADAMS. The main contribution of this article to bicycle dynamics is the analysis of tyre and rider properties that influence bicycle stability. A system identification method is used to extract linear stability properties from time domain analysis. The weave and capsize eigenmodes of the bicycle-rider system are analysed. The e...

  13. Fuzzy Reasoning as a Base for Collision Avoidance Decision Support System


    brcko, tanja; Švetak, Jelenko


    Despite the generally high qualifications of seafarers, many maritime accidents are caused by human error; such accidents include capsizing, collision, and fire, and often result in pollution. Enough concern has been generated that researchers around the world have developed the study of the human factor into an independent scientific discipline. A great deal of progress has been made, particularly in the area of artificial intelligence. But since total autonomy is not yet expedient, the deci...


    Institute of Scientific and Technical Information of China (English)


    Chinese fund management companies spilled red ink in the first half of 2010 as the stock market turned bearish. The shipbuilding industry regains its lost ground but unsteady seas could capsize hopes for continued success. Chinese property developers’ financing woes are inten- sifying. China Mobile reported modest growth in first-half profits as compe- tition heats up among the telecom giants. Outbound M&A deals, especially those involving natural resources, by Chinese companies in the first half of this year hit a record high. China aims to lift its installed hydropower capac- ity to 300 million kilowatts by 2015 from the current 200 million kilowatts.

  15. ACSNI study group on human factors

    International Nuclear Information System (INIS)

    Organisational failures are now recognised as being as important as mechanical failures or individual human errors in causing major accidents such as the capsize of the Herald of Free Enterprise or the Pipa Alpha disaster. The Human Factors Study Group of the Advisory Committee on the Safety of Nuclear Installations was set up to look at the part played by human factors in nuclear risk and its reduction. The third report of the Study Group considers the role played by organisational factors and management in promoting nuclear safety. Actions to review and promote a safety culture are suggested. Three main conclusions are drawn and several recommendations made. (UK)

  16. The utilization of natural gas in the electricity production through fuel cell; A utilizacao do gas natural na geracao distribuida atraves de celulas combustiveis

    Energy Technology Data Exchange (ETDEWEB)

    Bernardi Junior, Paulo


    In function of the necessity of electric energy as input of vital importance for the development of the country, this work aims at to offer plus an energy alternative for Brazil. The exploitation of the natural gas reserves recently discovered can be made through modern methods that give as priority the distributed generation and the low ambient impact. All these aspects can be gotten with the use of fuel cell, working with the remodelled natural gas. Increased to the factor of a low ambient impact in the proper generation, the project suggests that the generating source can be located next the consumer, diminishing still more the problems generated for transmission lines, fuel transport, etc. The fuel cell has received a great attention in the international community and some models, some already in commercial period of training, they have shown excellent possibilities of capsize to be one of the future technologies in the generation of electric energy with low ambient impact. (author)

  17. Reliability Analysis of Dynamic Stability in Waves

    DEFF Research Database (Denmark)

    Søborg, Anders Veldt


    accidents in the past. The rules therefore only leaves little room for evaluation and improvement of safety of a ship's dynamic stability. A few studies have evaluated the probability of ship stability loss in waves using Monte Carlo simulations. However, since this probability may be in the order of 10......-4 per ship year such brute force Monte-Carlo simulations are not always feasible due to the required computational resources. Previous studies of dynamic stability of ships in waves typically focused on the capsizing event. In this study the objective is to establish a procedure that can identify...... "critical wave patterns" that most likely will lead to the occurrence of a considered adverse event. Examples of such adverse events are stability loss, loss of maneuverability, cargo damage, and seasickness. The adverse events related to dynamic stability are considered as a function of the roll angle...

  18. Outline of The probabilistic Concept of Ship Subdivision

    DEFF Research Database (Denmark)

    Pawlowski, Maciej


    An outline of the whole probabilistic concept of ship subdivision is given, comprising the latest advances in determination of pi and s1 factors - the two probabilistic factors that form the basis of the new regulations.The method for calculating the pi factor for dry cargo ships is thoroughly...... presented and compared with the original method, developed by IMO inthe late 60's for passenger ships. After that, a review is presented of the past efforts to develop an estimate for the factor si - the most difficultand controversial part of the new subdivision regulations based on the probabilistic...... concept. This may facilitate our present efforts in developing a sound assessment, consistent with the results of damage stability model tests. A new method is provided regarding the capsizal probability, based on the theory underlying numerical simulations of damaged ship behaviour in natural sea...

  19. Sottotitolazione intralinguistica e inglese ‘lingua franca’: strategie di mediazione audiovisiva

    Directory of Open Access Journals (Sweden)

    Pietro Luigi Iaia


    Full Text Available Abstract – This chapter illustrates the results of a workshop held at the University of Salento, during an English-Italian Translation Course. A group of undergraduate students was asked to produce an intralingual translation for the subtitles of the video Capsized in Lampedusa – Fortress Italia, which deals with the situation in Lampedusa after a boat capsized in October 2013. The original video – available on YouTube – is subtitled into English for Vice News and, in a ‘role play’ exercise (Rosnow 1990, students were commissioned to adopt a type of English that could be directed at a wider international audience also including non-native English speakers. The contrastive analysis of the original and reformulated versions is designed to enquire into the influence and actualisation of the commissioner’s requests in the lexical, structural and functional features of target texts. The extent will also be explored, to which the type of English adopted in the alternative subtitles can be defined as a lingua-franca variation (Seidlhofer 2011, due to the inclusion of specific verb tenses and the selection of simplified syntactic structures (Seidlhofer 2004, aimed at facilitating the audience’s reception and accessibility to the semantic dimensions of the text. Finally, the analysis will also highlight the translators’ attempts to respect the temporal and spatial constraints of subtitles (Neves 2009, as well as the multimodal construction (Kress and van Leeuwen 2006 of audiovisual texts, which result in the use of condensation strategies (Gottlieb 2005; Pedersen 2011, thus proposing the new definition of audiovisual mediation.

  20. Nonlinear Container Ship Model for the Study of Parametric Roll Resonance

    Directory of Open Access Journals (Sweden)

    Christian Holden


    Full Text Available Parametric roll is a critical phenomenon for ships, whose onset may cause roll oscillations up to +-40 degrees, leading to very dangerous situations and possibly capsizing. Container ships have been shown to be particularly prone to parametric roll resonance when they are sailing in moderate to heavy head seas. A Matlab/Simulink parametric roll benchmark model for a large container ship has been implemented and validated against a wide set of experimental data. The model is a part of a Matlab/Simulink Toolbox (MSS, 2007. The benchmark implements a 3rd-order nonlinear model where the dynamics of roll is strongly coupled with the heave and pitch dynamics. The implemented model has shown good accuracy in predicting the container ship motions, both in the vertical plane and in the transversal one. Parametric roll has been reproduced for all the data sets in which it happened, and the model provides realistic results which are in good agreement with the model tank experiments.


    CERN Multimedia



    INTERNAL RAGATTE - BEST EVER ! If you missed Internal Regatta III on Sunday 11 July, you missed one of the best we can recall! The winds were about perfect, fairly stable Bf 2 with periodic gusts higher and the resulting capsizes to keep crews concentrating. It was extremely hot but we ran the usual three heats for keelboats and a record four for dinghies, catamarans - where there was another record, surely: a total of 11 boats in that class, of which three privately owned by members. And a final record: we calculate five boats were competing in their first-ever regatta. Results on the webpage. Surprisingly for those who remember regattas of a couple of years back, only three keelboats competed, so there would have been plenty of scope for less experienced members to come along regardless and probably find themselves a place. It is also noteworthy that the keelboat winner was Andrea Messina with an - ummm, may I say - less experienced crew himself! We hope this win bodes well for his forthcoming Transl&am...


    CERN Multimedia



    The Dinghy weekend A recent full weekend was run for dinghies: thanks to dedicated help from regular dinghy sailors and teachers, a lot of people overcame their uncertainty or lack of knowledge about dinghies, getting wet, what the gennaker actually does (and why it’s different from a spinnaker), and had good fun. Our trusty Surveillance boat put in a lot of hours (and petrol!) ensuring no-one came to any harm, thanks Christian (pictured) and Rob. It has to be admitted, winds were not, errr, challenging, for most of that weekend: we old salts know that as soon as the weather gets hot, winds abandon us until the autumn. That is a slight exaggeration but remains fact-based - like the old chestnut that if Mont Blanc is wearing a hat of clouds, it’ll rain soon! It was still wet-suit weather, for safety and because voluntary capsizes were on the programme - until you have done a few, you do not overcome a natural fear of them and they are an integral part of sailing a small dinghy compe...

  3. Role of an advanced spill avoidance system for oil tankers utilizing vacuum technique

    International Nuclear Information System (INIS)

    The SPILLSTOP is an active control system that controls the underpressure in the tank ullage space to a value that would prevent the amount of oil spillage to the volume above the line of rupture. The SPILLSTOP lends itself to a simple retrofit to existing tankers with an inert gas system installed, primarily as a containment device or as a contingency to other costly approaches. The SPILLSTOP system can also play a vital role by making the double hulled tanker safer from the danger of capsizing if the inner hull is ruptured. The system is equally adaptable to barges and smaller tankers without inert gas systems. It allows for instant corrective action when an accident occurs. An important aspect of the system is the computerized control of all the sensors monitoring the status of individual tank conditions such as pressure, oxygen and hydrocarbon concentration levels and cargo levels. This continuous readout is accomplished utilizing the information from the tank sensors and the supporting machinery for automatic control of the system. The SPILLSTOP is designed to ensure that a stabilizing underpressure exists in the tanks at the time rupture occurs, thereby minimizing the outflow of pollutants. This is achieved by (i) introducing inert gas in accordance with IMO standards, (ii) evacuating the tanks to required underpressure immediately after the tanks are loaded and (iii) maintaining the ullage gas mixture below the flammability zone. This immediate initiation of the underpressure recognizes and reduces the hazard of accidents that may occur in proximity to the coastline and to heavily populated areas

  4. A Proposal for Preventing Marine Accidents Caused by Dangerous Seas Using Emerging Bi-static Radar Technology (United States)

    Gleason, S.


    The dangers encountered while navigating the world's oceans are well known. The lives lost due to unsuspecting ship captains venturing into unknown dangerous seas is staggering. However, it appears that advances in ocean remote sensing technology may soon present a solution to this age-old problem; only the political will remains to be persuaded. This new technology involves utilising the signals transmitted by navigation satellites, such as those of the GPS system and in the future those of the Galileo constellation. These signals are constantly being scattered off the surrounding seas and land, and these signals contain valuable and varied information on the Earth's environment. The scientific applications of this technology tend to concentrate on obtaining high accuracy measurements, such as a precise sea surface height or the mean square wave slopes, for use in improving modelling and in advancing our understanding of ocean science. These pursuits are unquestionably worthwhile, but it is often overlooked that by simplifying our requirements, such as to being able to distinguish dangerous seas from those that would be passable by the great majority of ships, a great advance in human well-being could possibly be achieved. The fact that this technology uses passive signals and does not require a transmitter opens up additional possibilities by potentially greatly reducing the cost of such projects. A plan will be presented in this paper as to how this technology could enable relatively low-cost systems that could provide dense spatial coverage of the entire globe at high repeat times that could be provided to marine users and hopefully avoid maritime disasters. The monitoring and coverage of specific areas, such as the west coast of Africa will also be looked into in detail using more modest satellite configurations. These efforts are designed to focus on preventing disasters like the capsizing of the Senegalese passenger ferry "Joola" that occurred in September

  5. The City Image of Dostoevsky's Petersburg%陀思妥耶夫斯基笔下的彼得堡城市意象

    Institute of Scientific and Technical Information of China (English)

    傅星寰; 张一莹


    陀思妥耶夫斯基笔下的彼得堡城市意象——阴郁之花、神幻之城、罪恶之都、呼求悔改的"尼尼微",传达和推进了他的"彼得堡文本"的主题——"人之谜"的情感哲思、对俄罗斯现代性地批判、给予俄罗斯以及俄罗斯人未来道路选择的箴言,统摄着他的"彼得堡文本"的氛围和基调,形成了他富有特殊魅力的艺术表现.这些融入作家感怀的城市意象,源于现实又超越于现实之上,饱含了作家的文化批判及预言性质的深刻洞见.这些意象最终指向彼得堡的救赎之路,陀氏看到了传统观念终将经受洪水而倾覆的彼得堡有在信仰中被赎救的可能,从而藉着他的"彼得堡文本",给予彼得堡传统末日神话一个新的出路,盼望彼得堡成为响应呼召悔改后"新生"的城市.%The city image of Dostoevsky's Petersburg —Dark flowers,Magic City,Sin City,Call for repen-tance's 'Nineveh',communicated and promoted his "Petersburg text" theme—the emotion philosophy a-bout "mystery of the people",the modernity criticism of Russia,the proverbs given to choose the future path of Russia and the Russian,controlled his "Petersburg text" atmosphere and tone,and formed the special charm of artistic expression.These city images,which reflect the writer's lament and sentiment, come from life and beyond the reality,and fully reflect the writer's profound insight of cultural criticism and prophetic nature.These images finally point to the redemption road of Petersburg.Dostoevsky per-ceived that the traditional Petersburg would be capsized by flood finally,and there was possible to be saved in faith.Thereby,Dostoevsky created a new way for traditional doomsday myth of Petersburg via his"Pe-tersburg text",and hoped that Petersburg would become a"new city",which responses to calling for the repentance.

  6. Evidence of stratabound liquefaction in the formation of fractured topographic margins, cone chains and pit catenas along the Martian Dichotomy Boundary and in Isidis Planitia, Mars. (United States)

    Gallagher, C.; Balme, M. R.


    role in at least one mode of catena formation [2]. As well as presenting the morphological evidence for a genetic association between TPT and pit catenas, we present corroborative evidence that fluvial channel networks on Mars have in places increased in complexity through the linking of pits arranged in linear to arcuate arrays, culminating in a pseudo-branching channel network. Such systems do not occur at topographic margins and did not disintegrate into stepped crustal blocks. However, the scale of these channels and the volumes of liquid intermittently impounded in craters along these channel systems indicate that pit chains are associated with significant excess groundwater production leading to channelized flow, including catastrophic discharges when crater-impounded lakes along-flow were breached. Are the MDB and Isidis cone chains exhumed pit catenas and are the pits the surface expression of more deep-seated conduits? Do pit catenas indicate excess pore-water production, sufficient to link individual pits and dissect crustal blocks? Together, do these assemblages reflect the degradation of the MDB and Isidis margins and the subsequent stripping of adjacent low-lying plains? The crucial observations presented in this research (cone chains lying between crustal blocks, together with the morphometric similarities) are consistent with the interpretation of the cones and catenas having a common origin. Consequently, we hypothesise that the translated, back-rotated, tilted and capsized disposition of en echelon blocks is very reminiscent of the morphology produced during lateral spreading [3] associated with stratabound liquefaction below a low-gradient, rigid, insensitive surface. Significantly, such liquefaction events cause extensive, arcuate ground fractures along with the discharge of sediment-laden groundwater from the liquefiable substratum to the surface through pipes and conical boils confined within inter-block fractures. These conduits and their

  7. La banque de données platform de l'Institut français du pétrole : un outil de base pour des études de risque Ifp's Platform Databank: a Basic Implement for Risk Analysis

    Directory of Open Access Journals (Sweden)

    Bertrand A. R. V.


    having actually led to accidents. Such figures are very much appreciated in safety risk analysis. Several statistical results are given to illustrate PLATFORM's capacities. An analysis of activity at the time of the accident shows that most accidents occurred (in order during exploration drilling, during production, while rigs were under tow, while rigs were shut down during a storm, during development drilling, and during jacking-up or jacking-down for this type of mobile platform. In fact, 76. 6% of the accidents to jackups occurred either during towing (30. 9%, exploration drilling (27. 1% or jacking operations (18. 6%. Accidents to fixed platforms occurred predominantly during production (53%. The most frequent types of accident were found to be (in order blowouts, explosions or fires, damage to legs or mats often due to the sea floor, capsizing of the rig, gas kicks and structural cracks. But the major risk varied according to the type of platform : gas blowouts for submersibles, fire/explosions for fixed production platforms, capsizing for barges, sea floor accidents for jackups, gas kicks for drillships and semi-submersibles. A geographic analysis gives the Louisiana sector of the Gulf of Mexico a higher percentage of accidents (37% than the Texas sector (7. 5% or the Scottish North Sea (8%. This can easily be explained both by the relative importance of petroleum activity in the sector (especially barges and submersibles operating in swamps, lakes and deltas and by the comparable wealth of information made public in this region. A further analysis of the region shows more gas blowouts (28% than the world average (21% and, on the other hand, a chronological decrease in accidents linked to structural resistance, reflecting better rig design and reliability over the years. In general, statistics of accidents, correlated to offshore oil activity, show that accidents are decreasing in the Gulf of Mexico and in Persian Gulf, whereas there are more in the North Sea