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IMPORTANCE OF SOIL DILATANCY AND 3D EFFECTS IN BRACED EXCAVATION BPROBLEMS AND ITS APPLICATION TO STRESS-DEFORMATION ANALYSIS

土体剪胀性和三维效应在支撑开挖 B 问题中的重要性及其在应力变形分析中的应用

基本信息

批准号：
14350257
负责人：
NAKAI Teruo
金额：
$ 7.94万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14350257/
关键词：
Braced excavation Construction sequnce FEM 3D effects Constitutive model for soils Model tests Numerical Analysis

项目摘要

How to predict the surface settlements of the ground and how to evaluate the earth pressure on the braced wall are serious problems at open excavation in urban area. However, in the present practical methods, the earth pressure is usually predicted by conventional methods such as a frame model together with Rankine's earth pressure theory. There is also no appropriate method to predict the surface settlements of ground-usually empirical method and/or elastic finite element method are commonly used. In addition to this, finite element analysis is usually carried out assuming two-dimensional condition such as plane strain condition. The ground movements and earth pressure are much influenced by the construction sequence including three-dimensional effect, which are not considered in these conventional methods.This research has been carried out to investigate the ground movements and the earth pressures during braced excavation and devise proper and economic open excavation methods in urban area. For this purpose, we carried out elastoplastic finite element analyses in which the mechanical behavior of soils, structures and interface between soil and structure are properly taken into consideration, together with the corresponding model tests. Main contents of the present research can be summarized as follows :●Investigate the influence of the stiffness of wall and strut on surface settlements and earth pressure due to braced excavation●Investigate the influence of excavation sequence (including the arrangement of struts) on the surface settlements and earth pressure.●Verify the usefulness of a newly proposed exaction method, in which no strut is used in excavation and temporary retaining wall is used as a part of permanent structure.●Characterize three-dimensional effects of tunnel excavation on surface settlements and earth pressure.

如何预测地表沉降量和如何估算支撑墙上的土压力是城市露天开挖中亟待解决的问题。然而，在目前的实用方法中，土压力的预测通常采用框架模型结合朗肯土压力理论等传统方法。地表沉降量的预测也没有合适的方法--通常采用经验方法和/或弹性有限元方法。此外，有限元分析通常在平面应变等二维条件下进行。针对常规开挖方法中没有考虑三维效应的施工顺序对地表移动和土压力影响较大的问题，研究了城市开挖过程中的地表移动和土压力，设计出合理、经济的城市露天开挖方法。为此，我们进行了弹塑性有限元分析，适当地考虑了土、结构和土-结构界面的力学行为，并进行了相应的模型试验。本文的主要研究内容可概括如下：研究墙体和支撑的刚度对支撑开挖引起的地表沉降量和土压力的影响，考察开挖顺序(包括支撑的布置)对地表沉降量和土压力的影响，验证新提出的开挖不使用支柱，临时挡土墙作为永久结构的一部分的提取方法的有效性，表征隧道开挖对地表沉降量和土压力的三维效应。