基坑隆起稳定性数值分析中的若干问题

Some problems in numerical analyses of basal upheaval stability of foundation pits

基坑隆起稳定性数值分析是深基坑工程研究中的重要方法,尚处于初步探讨阶段,还存在一些重要的科学问题有待深入认识。基于国内外这方面的研究成果并结合笔者在软土基坑三维数值参数分析工作中的经验,对基坑隆起稳定性数值分析中的隆起破坏空间效应、破坏模式、本构模型及参数选择等问题进行了初步探讨,指出隆起稳定分析应重点开展三维和窄长基坑双侧隆起分析;破坏模式辨识中,隆起模式未必与传统方法的破坏模式相同;土体本构模型选择应主要考虑土体加卸荷条件以及屈服与破坏准则;参数分析中,首次指出本构模型参数选择存在可行域问题。

Numerical analysis of basal upheaval stability of foundation pits is a very important method in researches on deep excavation engineering, which is in the initial development stage and is of important issues remained to be understood and solved. Based on analysis of the results of the corresponding researches, combining the experience gained from the researches in three-dimensional parametric analysis of excavation in soft soils, the problems such as spatial effects, failure patterns, selection of soil constitutive models and their parameters are analyzed. Both the three-dimensional analyses and the bilateral plain analyses of basal upheaval stability are emphased. The differences of failure patterns of basal upheaval from numerical analyses and those from the traditional analytical methods in failure pattern recognition are revealed. The great importance should be attached to the loading and/or unloading criteria and yield and failure criteria in selection of soil constitutive models and their parameters. The concept of feasible region for parameters in parametric analysis is firstly put forward.