Failure processes in a full-scale landslide experiment using a rainfall simulator   总被引：8，自引：1，他引：7  

H.?MoriwakiEmail author  T.?Inokuchi  T.?Hattanji  K.?Sassa  H.?Ochiai  G.?Wang 《Landslides》2004,1(4):277-288

A full-scale landslide experiment was conducted to clarify the failure process of a landslide triggered by rainfall, using a loose sandy soil. The experiment used a 23-m long and about 8-m high flume, consisting of three parts: an upper 30° slope section, a lower 10° slope section, and a horizontal section at the foot of the slope. The flume was sprinkled at a constant intensity of 100 mm/h. The landslide occurred first in the upper slope about 154 min after the sprinkling started, following a creep movement within 41 min. The sliding mass slid to a stop in about 5 s, compressing soils in the lower gentle slope and horizontal sections. The dynamic process related to slide movement and the fluctuation of subsurface water pressures during failure were measured and analyzed. Sequential visual observations provided a clear record of the slip surface during failure. The rapid increase of subsurface water pressure in the slope and horizontal soil layers was also recorded during failure. It was inferred that the increased water pressures in the upper slope resulted from collapse of loose soil structure during shearing in the translational slide, whereas those in the lower portion of the slope and horizontal sections resulted from a mix of soil compression and shearing by the sliding mass.  相似文献   

地震作用下串、并联工程系统中结构失效相关性的近似处理   总被引：25，自引：3，他引：22  

王光远  朱靖华 《地震工程与工程振动》1998,18(4):1-7

“工程系统”指的是工程项目所包括的主要工程结构的集合。当工程项目具有不止一个主要结构时,各结构单独优化的所组成的集合不一定是全局最优的工程系统。工程系统全局优化过程中非常重要的一环就是该系统失效概率的计算。这时必须考虑而又非常困难的问题就是系统中各个结构之间失效相关性的问题。我们认为,在自然灾害作用下各结构之间的失效相关性主要决定于自然灾害的程度,强度愈高相关性就愈大。据此,给出了这个问题的近似处  相似文献   

细观非均匀性对岩石破裂过程和微震序列类型影响的数值试验研究   总被引：15，自引：1，他引：15       下载免费PDF全文

焦明若  唐春安  张国民  石耀霖  侯万凯 《地球物理学报》2003,46(5):659-666

运用岩石破裂过程分析RFPA2D系统，研究了岩石介质细观非均匀性对宏观力学行为的影响和微震序列特征. 通过对不同均质度系数m=1.1，1.5，2，3，5的5个样本进行破裂过程的模拟，发现均质度不同会产生不同地震序列类型，主要有：前震-主震-余震型、主震型和震群型. 此外，对5种不同均质度系数的岩石样本破裂过程的模拟表明，岩石介质的非均匀性不仅对岩样宏观强度和宏观变形非线性行为有显著的影响，而且也显著地影响试样破裂模式. 随着均质度系数的提高，主破裂呈现脆断模式. 同时介质的细观结构随机性，也对试样宏观破裂模式产生重要影响.  相似文献   

Seismic reliability analysis of earth slopes under short term stability conditions   总被引：1，自引：0，他引：1  

Azm S. Al-Homoud  Wisam W. Tahtamoni 《Geotechnical and Geological Engineering》2002,20(3):201-234

Different models were developed for evaluating the probabilistic three-dimensional (3-D) stability analysis of earth slopes and embankments under earthquake loading. The 3-D slope stability model assumed is that of a simple cylindrical failure surface. The probabilistic models evaluate the probability of failure under seismic loading considering the randomness of earthquake occurrence, and earthquake induced acceleration and uncertainties stemming from the discrepancies between laboratory-measured and in-situ values of shear strength parameters. The models also takes into consideration the spatial variabilities and correlations of soil properties. The probabilistic analysis and design approach is capable of obtaining the 2-D and 3-D static and dynamic safety factors, the probability of slope failure, the earthquake induced acceleration coefficient, the yield acceleration coefficient, the earthquake induced displacement, and the probability of allowable displacement exceedance taking into account the local site effect. The approach is applied to a well known landslide case: Congress Street Landslide in Chicago. A sensitivity analysis was conducted on the different parameters involved in the models by applying those models to the Congress Street landslide considering different levels of seismic hazard. Also, a sensitivity analysis was carried out to study the sensitivity of computed results to input parameters of undrained shear strength, and corrective factors. A comparison was made between the different models of failure. The parametric study revealed that the hypocentral distance and earthquake magnitude have major influence on the earthquake induced displacement, probability of failure and dynamic 2-D and 3-D safety factors.  相似文献   

Seismic stability of retaining walls with surcharge   总被引：6，自引：0，他引：6  

S. Caltabiano  E. Cascone  M. Maugeri 《Soil Dynamics and Earthquake Engineering》2000,20(5-8):469-476

The use of pseudo-static methods for the computation of soil thrust acting on retaining walls under seismic condition is well established in the design of such structures. Although different methods, based on the limited displacement concept, have been developed in the last 20 years, the most common design method is still the method derived from the theory developed by Mononobe and Okabe. However, the Mononobe–Okabe method presents a basic shortcoming: the solution is based on the limit equilibrium of the soil wedge without taking into account the presence of the wall. In the paper a new solution based on the pseudo-static equilibrium of the soil–wall system is presented. The developed solution takes into account the effect of the presence of the wall and it is applied to soil–wall systems with surcharged backfills. Formulas are provided to calculate directly the yield acceleration and the inclination of the failure surface. The effect of the intensity of the surcharge and of its distance from the wall is investigated and the results are compared to those obtained in the case of soil–wall systems without surcharge.  相似文献   

岩体边坡滑裂面随机搜索机理与工程应用--以黄河小浪底水库进口高边坡泻洪、发电、引水建筑物进口高边坡为例   总被引：2，自引：1，他引：1  

周萃英 《工程地质学报》2000,8(2)

本文运用随机搜索和破坏概率相结合的技术方法 ,以黄河小浪底水库进口高边坡引水建筑物咽喉工程为例 ,进行了滑动面的随机搜索和边坡的破坏概率分析 ,给出了不同条件下最危险滑面的最低位置和倾角以及边坡破坏概率最大时的荷载组合形式 ,指出 1:0 .2的台阶坡设计优于直立坡的设计。同时 ,为边坡加固的锚固长度和范围的确定提供了合理依据。  相似文献   

Changes in structural style of normal faults due to failure mode transition: First results from excavated scale models     

《Journal of Structural Geology》2015

The effects of failure mode transition from tensile to shear on structural style and fault zone architecture have long been recognized but are not well studied in 3D, although the two modes are both common in the upper crust of Earth and terrestrial planets, and are associated with large differences in transport properties. We present a simple method to study this in physical scale models of normal faults, using a cohesive powder embedded in cohesionless sand. By varying the overburden thickness, the failure mode changes from tensile to hybrid and finally to shear. Hardening and excavating the cohesive layer allows post mortem investigation of 3D structures at high resolution. We recognize two end member structural domains that differ strongly in their attributes. In the tensile domain faults are strongly dilatant with steep open fissures and sharp changes in strike at segment boundaries and branch points. In the shear domain fault dips are shallower and fault planes develop striations; map-view fault traces undulate with smaller changes in strike at branches. These attributes may be recognized in subsurface fault maps and could provide a way to better predict fault zone structure in the subsurface.  相似文献   

A discrete numerical approach for modeling face stability in slurry shield tunnelling in soft soils     

Z.X. Zhang  X.Y. Hu  Kieffer D. Scott 《Computers and Geotechnics》2011

In this paper, a numerical simulation method for evaluating tunnelling-induced ground movement is presented. The method involves discrete element simulation of TBM slurry shield advancement and considers explicitly soil excavation from the face, effects of varying face support pressure, and the influence of tunnel cover depth. For the cases studied, it is found that for tunnel cover depths (C/D) between 0.7 and 2.1, ground deformations inducing by the tunnelling can be controlled within a certain extent and tunnel face stability can ensured, provided the support pressure ratio (N) lies between 0.8 and 1.5. The proposed method is reasonably benefited to modeling the face stability in shield-driven tunnels in soft soils.  相似文献   

基于点估计法的黄土边坡可靠度研究   总被引：1，自引：0，他引：1  

张亚国  张波  李萍  李同录 《工程地质学报》2011,19(4):615-619

在不同的黄土地区选取4个工点的典型路堑高边坡,基于点估计理论和有限元强度折减法计算边坡可靠指标。结果表明:工点2的稳定系数虽达到1.46,却有19.2%的失效概率; 工点1和4的坡型、地层岩性及层厚等工况较接近,失效概率差值达29.8%,参数变异性是造成其差异的主要原因。用点估计法计算边坡可靠度,并采用可靠度理论分析黄土边坡稳定性,能较好的解决土性参数离散性对边坡稳定性评价的影响。  相似文献   

Deformation of rubble-mound breakwaters under cyclic loads   总被引：1，自引：0，他引：1  

K. Cihan  Y. Yuksel 《Coastal Engineering》2011

Rubble-mound breakwaters usually consist of a core of small quarry-run rock protected by one or more intermediate layers or underlayers that separate the core from the cover layers, which are composed of large armor units. Failure of rubble-mound breakwaters may be due to effects such as removal or damage of the armor units, overtopping leading to scouring, toe erosion, loss of the core material, or foundation problems under waves. However, whether rubble mounds fail under seismic loads is unknown. High seismic activity can lead to large settlements and even to failure of the breakwaters. The design of coastal structures should take into account the most relevant factors in each case, including seismic loading. The objective of this study is to understanding the failure mechanisms of conventional breakwater structures under seismic loads on rigid foundations. Hence, an experimental study was carried out on conventional breakwater structures with and without toes, subjected to different dynamic loadings of variable frequencies and amplitudes, in a shaking tank. A shaking tank with a single degree of freedom was developed to study the simple responses of conventional rubble-mound breakwaters under cyclic loads. For each test, an automatic raining crane system was used to achieve the same relative density and porosity of the core material. The input motion induced horizontal accelerations of different magnitudes during the tests. The accelerations and the deformation phases of the model were measured by a data acquisition system and an image processing system. The experiments on the conventional rubble-mound type breakwater model were performed under rigid-bottom conditions. The model's scale was 1:50. Cyclic responses of breakwaters with toes and without toes were examined separately, and their behaviors were compared. The results were compared with a numerical study, and the material properties and failure modes were thus defined.  相似文献