Mechanical behavior of soft clay improved with lime cloumn during vertical excavation

垂直开挖过程中石灰块改善软粘土的力学性能

基本信息

批准号：
03555110
负责人：
KIMURA Tsutomu
金额：
$ 5.95万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03555110/
关键词：
excavation sheet pile soft clay soil improvement stability deformation earth pressure centrifuge model test 軟弱地盤柱体改良地盤

项目摘要

A centrifuge excavator with which the process of excavation can be simulated in-flight was developed and a study on the mechanical behavior of soft clay during excavation using the centrifuge excavator is reported here. In this study three series of centrifuge tests were carried out. In the first series, the effect of undrained strength increase with depth on the stability of vertical cuts was investigated by centrifuge model tests in which prepared models were brought to failure by increasing centrifugal acceleration. In the second series, unsupported excavation and excavation with a supporting wall with or without ties were conducted with the excavator for two types of soft clay, namely normally consolidated and lightly overconsolidated clays. Earth pressures on sheet pile walls and deformations of the walls and clay were measured during excavation. In the third series. excavation with supporting wall without tie for normally consolidated clay improved with lime piles in active side … More were conducted by using the excavator. The effect of improvement and mechanical behavior of improved groud during excavation were investigated.The analyzes of the test results provided the following conclusions.1)The mechanism of failure in excavation with sheet pile walls without ties is different for clay grounds with uniform strength and increasing strength. For the former the wall shows translational movement with well-defined linear slip surface both in the active and passive side, while for the latter the wall tilts around the bottom with linear slip surface only in the active side.2)In excavation with sheet pile walls without ties, the embedment does not contribute to the stability in clay with uniform strength. but stability number increases significantly with depth of embedment in clay with increasing strength.3)The characteristics of clay in the active state have a dominant effect on the deformations and strains of sheet pile walls.4)The improvement with lime piles in the active side of sheet pile without tie reduces strains of sheet pile and active pressures on sheet pile walls, and in effective in increasing the stability of excavation. Less

开发了一种可以在飞行中模拟挖掘过程的离心挖掘机，并在本研究中报告了使用离心挖掘机挖掘过程中软粘土的力学行为。在第一个系列中，通过离心模型试验研究了不排水强度随深度增加对垂直切口稳定性的影响，其中准备好的模型通过增加离心加速度而失效。使用挖掘机对两种类型的软粘土进行无支撑开挖和有支撑墙开挖，即正常固结粘土和轻度超固结粘土，并在开挖过程中测量板桩墙的土压力以及墙和粘土的变形。在第三个系列中，使用挖掘机对正常固结的粘土进行了开挖，并使用挖掘机进行了改进后的土体的改进效果和机械性能。试验结果得出以下结论：1)无拉杆板桩墙开挖破坏机理与强度均匀和强度递增的粘土地基不同。在主动侧和被动侧均具有明确的线性滑移面，而对于后者，墙壁围绕底部倾斜，仅在主动侧具有线性滑移面。2）在没有拉杆的板桩墙开挖中，埋置没有贡献均匀粘土中的稳定性强度随粘土埋入深度的增加而增加，但稳定值随着强度的增加而显着增加。3）活性状态下粘土的特性对板桩墙的变形和应变具有主导作用。4）石灰桩在土体中的改进。板桩主动侧不减少板桩的拉结应变和板桩壁的主动压力，且能有效提高开挖稳定性。