Stability of deep excavation in soft clay deposits-Deformation and interaction with adjacent structure-

软粘土矿床深基坑稳定性-变形及与邻近结构的相互作用-

基本信息

批准号：
09045048
负责人：
TAKEMURA Jiro
金额：
$ 1.09万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09045048/
关键词：
open braced excavation earth pressure soft clay centrifuge model tests deformation construction sequence 3D effects 軟弱粘土地盤掘削シミュレーション有限要素解析

项目摘要

In this study centrifuge model tests on vertical excavation in normally consolidated soft clay was carried out using a newly developed test systems in TIT and NUS.By TIT and NUS systems construction sequence in double propped wall open excavation and rectangular shape excavation can be properly simulated in flight respectively. The following conclusions were drawn.(1) The assumption of undrained condition can be reasonably adopted for NC clay during excavation because of positive pore pressure generation due to shearing.(2) Normally consolidated clay reached Rankine's active conditions at very shallow excavation depth before lower propping. The importance of strength anisotropy for the stability evaluation in open excavation was confirmed in the tests. The clay in the bottom of excavation reached its passive condition around the half of excavation depth. The deformation after this depth was mainly determined by the mechanical properties of sand, i.e., stiffness or stress-strain.(3) Pro … More pping can prevent marked increase in the settlement ; however, it is very difficult to recover the settlement and deformation once it occurs by increasing the strutting force (i.e., preloading). Hysteretic and non-linear behavior of soil is considered to be one of the main reasons of the irrecoverable deformation.(4) Difference in the settlement trough with different propping conditions mainly revealed near the wall, while for far away from the wall no much difference in the trough could be seen.(5) The wall deflection was derived from the data of two laser displacement transducers at different heights and strains along the wall. Although some scattering was included due to the inevitable error in the deflection calculation, a non-linear relation was clearly obtained between mobilized strength and deflection.(6) The corner constraint plays an important role in controlling wall and ground movement in an unstrutted 3D excavation. Increasing the thickness of the wall reduces the wall and ground movement. Less

在这项研究中，使用 TIT 和 NUS 新开发的测试系统，在正常固结的软粘土中进行了垂直开挖的离心模型试验。通过 TIT 和 NUS 系统，可以正确模拟双支撑墙露天开挖和矩形开挖的施工顺序。分别得出以下结论：(1)NC粘土由于剪切作用而产生正孔隙压力，开挖时可合理采用不排水条件假设。(2)一般情况下。在较低的支撑之前，固结粘土在开挖深度很浅时就达到了朗肯的主动状态。试验证实了开挖深度的一半左右，强度各向异性对于开挖稳定性评价的重要性。此深度后的变形主要取决于砂的力学性能，即刚度或应力应变。(3) Pro … 更多 pping 可以防止沉降的显着增加，但它的作用非常大；通过增加支撑力（即预压），一旦发生沉降和变形就难以恢复，土体的滞回和非线性行为被认为是不可恢复变形的主要原因之一。（4）沉降差异。不同支撑条件下的槽体主要在近壁处显露，而远离壁面则看不到太大差异。(5)壁面挠度由两次激光位移数据推导出来尽管由于挠度计算中不可避免的误差而包含了一些散射，但在移动强度和挠度之间清楚地获得了非线性关系。（6）角约束起着重要作用。控制无支撑 3D 挖掘中的墙和地面运动，增加墙的厚度会减少墙和地面的运动。