硬化土体模型分析基坑挡土壁与地盘变形的评估

Evaluation of analyzing excavation-induced wall deflection and ground movement using hardening soil models

基坑开挖引致挡土壁体和地盘变形预测的准确度,会显着影响基坑四周结构物损害潜能评估的正确性。运用有限元数值程序分析基坑变形问题时,土壤本构模型描述土壤行为的优劣居关键角色。采用工程界和学术界常用的数值软件PLAXIS中两个高级土壤模型(硬化土壤模型及硬化土壤小应变模型),分析一个著名的基坑开挖案例之壁体变形、地表沈陷和地盘水平变位,藉以评估两个土壤模型预测基坑开挖引致挡土壁体和地盘变形预测的准确度。分析结果显示:若土壤模型可以考虑小应变高初始刚度模量和刚度劲度随应变衰减的行为,可以更合理地预测开挖引致之壁体变形与地盘变形量。

The accuracy of predicting wall deflection and ground movement caused by excavation will significantly affect the accuracy of evaluation of potential damage of structures adjacent an foundation pit.The capability of constitutive law of soil in describing the soil behavior plays a crucial role in the numerical analysis of excavation using the finite element method.This study adopts two advanced soil models incorporated into the PLAXIS code,which is extensively used by engineers and researchers,to analyze the excavation-induced wall deflection,ground surface settlement,and lateral soil movement recorded in a well-documented excavation case history for evaluating the capability of the two soil models in accurately estimating the wall deflection and ground movement caused by excavation of the foundation pit.The analysis results reveal that the excavation-induced wall deflection and ground movement can be more reasonably predicted provided the high initial stiffness modulus and the degradation characteristics of stiffness modulus can be considered in the soil model.