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Study on the dynamic failure mechanism of a gravity caisson quay wall due to earthquake forces

地震力作用下重力沉箱码头墙动力破坏机理研究

基本信息

批准号：
11555128
负责人：
MIMURA Mamoru
金额：
$ 7.36万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11555128/
关键词：
centrifuge model test gravity caisson fault type earthquake liquefaction finite element analysis lateral displacement excess porewater pressure seismic behavior 過剩間隙水圧液状化抵抗原位置試験砂非排水繰返し三軸試験

项目摘要

A series of centrifuge tests was carried out to assess the seismic behavior of a gravity caisson quay wall with reclaimed backfill. The caisson model has been constructed with 3 water pressure cells and 3 earth pressure cells on the back of it to measure the water pressure as well as the earth pressure acting at the boundary between the caisson and the reclaimed backfill, that is thought to cause the seismic behavior of the gravity caisson due to earthquake force. Other pressure cells were installed in the reclaimed backfill and the replaced sand beneath the caisson to monitor the occurrence of liquefaction that may also become a main cause for the deformation of the gravity caisson quay wall. Effect of the physical properties of the frontal seabed, the shape of the gravity caisson and the frequency of the sinusoidal wave applied as a seismic force on the gravity caisson was mainly examined. The seismic force was applied to the backfilled caisson quay wall under 30G centrifugal conditi … More on.Liquefaction occurred in the reclaimed backfill whereas the partial liquefaction took place in the replaced sand beneath the caisson because of the increase in stress due to the existence of the gravity caisson. Due to the inertia force, decrease in the bearing capacity of the replaced sand and the dynamic pressure of the reclaimed backfill, the gravity caisson moved seaward with a frontal subsidence into the rubble mound. The measured lateral displacement of the caisson was about 40 cm in this particular case. Considering the scale effect, the derived displacement is found to be rational by comparing the achievement reported from the Hyogoken-Nambu Earthquake.Numerical analysis was also carried out using the code "LIQCA" to describe the performance of the centrifuge model tests. The parameters for the code have been rationally determined on the basis of the laboratory experiments on the same material used in the centrifuge model tests and the measured data by the centrifuge model tests. The derived accelerations both from the numerical analysis and the centrifuge model tests were filtered and compared. Both filtered accelerations showed a good match. Although the calculated displacement slightly overestimated the experimental one, the numerical results can precisely describe the experimental ones, particularly the process of generation/dissipation of the excess pore water pressure in the reclaimed backfill as well as the replaced sand beneath the caisson. From those results, the procedure with centrifuge model tests and the numerical assessment adopted in this research has been found to be useful to assess the in-situ performance of the gravity caisson quay wall with the reclaimed backfill quite well. Less

通过离心试验研究了重力式沉箱码头回填土的抗震性能。在沉箱模型的基础上，建立了3个水压力单元和3个土压力单元，分别测量了沉箱与回填土边界处的水压力和土压力，认为这是重力式沉箱在地震力作用下产生抗震性能的原因。在沉箱下方的回填土和替换砂中安装了其他压力传感器，以监测液化的发生，液化也可能成为重力沉箱码头壁变形的主要原因。主要研究了前缘海床的物理性质、重力式沉箱的形状以及作为地震力施加在重力式沉箱上的正弦波的频率对重力式沉箱的影响。在30 G离心力作用下，对回填沉箱码头岸壁进行了地震力加载试验， ...更多信息由于重力式沉箱的存在，应力增加，回填土发生液化，而沉箱下的置换砂发生部分液化。重力式沉箱在惯性力、置换砂承载力下降和回填土动压力作用下，向海方向移动，并向抛石堆体前方下沉。在这种特殊情况下，沉箱的实测横向位移约为40厘米。通过与日本兵库县南部地震实测结果的比较，考虑了尺度效应，得出了较为合理的位移计算公式，并利用LIQCA程序对离心模型试验结果进行了数值分析。根据离心模型试验所用相同材料的室内试验和离心模型试验的实测资料，合理地确定了规范的参数。对数值分析和离心模型试验得到的加速度进行了滤波和比较。两个过滤后的加速度都显示出很好的匹配。虽然计算位移略高于试验位移，但数值结果能准确描述试验位移，特别是回填土和换填砂中超静孔隙水压力的产生/消散过程。从这些结果中，离心模型试验和数值评估的过程中所采用的这项研究已被发现是有用的，以评估原位性能的重力沉箱码头与回填相当好。少