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Study on Three-dimensional Characteristics of Fill Failures for Safety Evaluation

充填破坏三维特征安全评价研究

基本信息

批准号：
06650551
负责人：
NARITA Kunitomo
金额：
$ 0.77万
依托单位：
Aichi Institute of Technology (A.I.T.)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

In order to study three-dimensional failure characteristics of fill and ground, centrifuge loading tests were first performed on level and slope sand foundations by changing the size of rectangular footing (zeta=L/B). Some remarks drawn in these tests were as follows ; (1) brittle failures showing sharp peak of load-settlement curve are observed as zeta increases, while the variation of the ultimate values of bearing capacity is small, (2) the shape factor reduces due to the decrease in zeta for level ground as proposed by DeBeer, whereas little change is seen in bearing capacity for slope foundation, (3) the size effect in the bearing capacity is observed in both level and slope foundations, (4) the existence of slope shows large difference in load bearing capacity, giving the value of 0.5 to 0.6 for the ratio between slope and level grounds ; (5) faiure surfaces observed in loading tests on sloping ground are clearly defined and they can be approximated mathematically in good accuracy by use of log-spiral curves.In another series of centrifuge model tests for three-dimensional failure aptterns of earthfills constructed on the sloping valley, model fills were forced to slide by moving the front suppporting wall during a constant centrifuge circulation, and sliding planes were determined after the circulation stops by surveying the positions of intersecting points of noodle-type strings embedded in the model fill. It was recognized in the tests that (1) the size of sliding bodies, their depth and horizontal extension, becomes large as the width of the valley increases because of the decrease in the effect of lateral constraint, and (2) similar tendency is observed in the conventional stability analysis for the observed sliding plane, the three-dimensional safety factors becoming close to the two-dimensional ones as the valley with increases.

为了研究填土和地基的三维破坏特性，首先通过改变矩形基础的尺寸（zeta=L/B），对水平和斜坡砂土地基进行了离心载荷试验。在这些测试中得出的一些评论如下：（1）随着zeta值的增大，荷载-沉降曲线出现尖峰的脆性破坏，但极限承载力变化不大;（2）对于DeBeer提出的水平地基，zeta值的减小使形状系数减小，而对于斜坡地基，极限承载力变化不大;（3）水平地基和斜坡地基的承载力均存在尺寸效应;（4）斜坡的存在使地基承载力有很大的差异，坡平比为0.5 ~ 0.6;（5）斜坡荷载试验中的破坏面有明确的定义，可以用对数方程在数学上很好地近似。螺旋曲线。在另一系列的离心模型试验中，对建造在倾斜山谷上的填土的三维破坏倾向进行了研究，在恒定的离心循环过程中，通过移动前支撑墙迫使模型填土滑动，在循环停止后，通过测量模型填料中嵌入的面条型线的交点位置来确定滑动面。试验结果表明：（1）由于侧向约束作用的减弱，滑动体的大小、深度和水平延伸范围随着谷宽的增大而增大;（2）对于观测到的滑动面，在常规的稳定性分析中也观察到类似的趋势，三维安全系数随着谷宽的增大而接近二维安全系数。