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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征，首先通过改变矩形基础（zeta=L/B）的大小，对水平和斜坡砂基础进行离心加载试验。在这些测试中得出的一些评论如下：(1)随着zeta的增大，脆性破坏呈现出荷载-沉降曲线的尖峰，而承载力的极限值变化不大；(2)DeBeer提出的水平地基由于zeta的减小而形状因子减小，而边坡基础的承载力变化不大；(3)水平地基和边坡基础的承载力均存在尺寸效应。(4)边坡的存在表现出较大的承载力差异，边坡与平地的比值为0.5 ~ 0.6；(5)斜坡荷载试验中观察到的破坏面定义清晰，可以用对数螺旋曲线进行数学近似，精度较高。在另一组斜坡谷土方三维破坏模式的离心模型试验中，在不断的离心循环过程中，通过移动前支承墙迫使模型土方发生滑动，通过测量模型土方中嵌入的面条型串的交点位置，确定循环停止后的滑动平面。试验结果表明：(1)由于侧向约束作用的减弱，滑体的尺寸、深度和水平延伸量随着山谷宽度的增大而增大；(2)传统的滑面稳定性分析也有类似的趋势，随着山谷宽度的增大，滑体的三维安全系数与二维安全系数趋于接近。