软土本构模型在深基坑环境影响分析中的适用性探讨

Applicability study of constitutive models in environment impact analysis for deep foundation pit

基坑降水开挖的环境影响常采用顺序耦合法和全耦合法两种方法进行数值分析,其计算结果的可靠性主要受土本构模型和计算参数选取的影响,对于全耦合分析尤其突出。针对该问题,在系统地比较分析几类常用土体本构模型优缺点的基础上,对某基坑实例在降水开挖作用下引起的基坑周边地面沉降等规律进行分析;通过对比数值计算结果和实测结果,评价了不同本构模型在基坑降水开挖耦合分析中的全耦合数值模拟,分析降水开挖引起的地面沉降、围护结构水平位移适用性。分析结果表明:降水开挖耦合分析中,在重点关注地表沉降值时,应根据关注位置与开挖区边缘的相对距离而选用不同本构模型;关注地面沉降时采用修正剑桥模型较合适,而关注围护结构侧移时采用摩尔—库伦模型更合理。

Sequential coupling analysis and fully coupling analysis are frequently used to analyze the influence of dewatering and excavation on the surroundings.The reliability of these analyses is mainly affected by the adoption of an appropriate soil constitutive model and corresponding computation parameters,especially for a fully coupling analysis.To 2016·Vol.37·№.185 investigate this issue,the advantages and shortcomings of several kinds of constitutive models were analyzed first.These models were then used to conduct fully coupling analyses for an excavation case.The ground settlement and deflection of retaining structures induced by dewatering and excavation were investigated.By comparing the numerical results to the measured results,the applicability of these models in coupling analyses was evaluated.The results demonstrated that in a fully coupling analysis,when ground settlement was the focus,the adoption of constitutive models should be determined according to the distance between the concerned point and the edge of deepest excavation.The Mohr-Coulomb model was recommended when the deflection of retaining structures was the focus.