An investigation on effects of countermeasures against liquefaction of sand deposits with structures

建筑物砂沉积物液化对策效果研究

基本信息

批准号：
07555445
负责人：
TAKEMURA Jiro
金额：
$ 1.28万
依托单位：
Tokyo Institue of Technoloty
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555445/
关键词：
liquefaction sand oil tank embankment model test sheet pile wall gravel drain settlement 矢板壁バーチカルドレーン矢板

项目摘要

Centrifuge model tests are carried out to study the effect of various countermeasures against liquefaction of sand deposits with an undergrond structure and a structure on surface. Model tests are conduced on five types of models ; one without any countermeasures and four with countermeasures ; sheet pile walls with or without drainage capability, sheet pile walls of which tops are tied with rods and gravel drains.Following conludsions are drawn from this study.1.For foundation soil with an underground structure, upward movements of it take place when excess pore pressure beneath the structure reaches a threshold value. In countermeasures to prevent the upward movement, an attempt should be made to keep the excess pore pressure lower than this threshold.2.Responses of acceleration of structures depend very much on the excess pore pressures generated in foundation soil. The acceleration responses at the very early stages of input motons are similar for all the cases, but the subsequcnt responsese differ for different types of countermeasure. For the cases without drainage, the acceliration of structure decreases with the generation of excess pore pressure. On the other hand, for the cases with drainage, the acceleration of structure increase.3.Settlements of structures on a ground surface like oil tank and embankment arise from two reasons ; the compression of sand beneath due to consolidation and the other the lateral movement of hte sand. Increase of lateral movement gives rise to an increase in total settlements of the structure, suppression of lateral spreading is necessary.

通过离心机模型试验，研究各种对策对地下结构和地面结构砂沉积物的液化效果。对五类模型进行了模型试验；一无对策，四有对策；有排水能力和无排水能力的板桩墙、顶部绑杆的板桩墙和砾石排水沟。通过研究得出以下结论：1.对于地下结构的地基土，当孔隙过多时，会发生向上运动结构下方的压力达到阈值。在防止向上移动的对策中，应设法使超孔隙水压力保持在该阈值以下。2.结构的加速度响应很大程度上取决于地基土中产生的超孔隙水压力。在所有情况下，输入运动早期阶段的加速度响应都是相似的，但后续响应对于不同类型的对策是不同的。对于不排水的情况，结构的加速度随着超孔隙水压力的产生而减小。另一方面，对于有排水的情况，结构的加速度增大。 3.油罐、路堤等地表结构的沉降有两个原因引起：由于固结而对下面的沙子进行压缩，另一个是沙子的横向移动。横向移动的增加会导致结构总沉降的增加，因此有必要抑制横向扩展。