常用土体本构模型在复杂环境深基坑数值计算中的选用

On selection of common soil constitutive models in numerical simulation of deep foundation pits under complex environment

建设用地日益紧张,基坑周边环境复杂,周边环境安全已成为基坑设计中的突出问题,而基坑环境评估数值计算的关键在于土体本构模型和物理参数的选取。结合镇江某深基坑工程,使用有限元分析软件Midas GTS NX对比分析了常用土体本构模型在基坑开挖数值模拟中的适用性。结果表明,弹塑性莫尔-库伦(Mohr-Coulomb,MC)模型由于采用统一计算刚度,导致围护结构变形和地表沉降与实际存在较大差异;硬化修正剑桥(Modified Cam-Clay,MCC)和硬化土(Hardening Soil,HS)模型能合理区分加载和卸载时的刚度,得到的变形与实测结果相符。在计算围护结构受力时,三者并无太大差别。因此,在分析基坑开挖所导致的场地土体变形时,建议采用硬化MCC或HS模型。

Due to the decrease of construction land,and the increasing complexity of the surrounding environment of the foundation pit,the surrounding environment′s safety has become a big concern in engineering design.The key in environmental assessment of the excavation by numerical simulation is the selection of soil constitutive models and physical parameters.Based on a deep foundation pit of Zhenjiang,the feasibility of common soil constitutive models in numerical simulation of excavation was analyzed by the finite element analysis software Midas GTS NX.Results indicate that there is a great difference in the deformation of envelope enclosures and ground settlement between the results by Mohr-Coulomb model(MC model)and actual monitoring data,due to the application of the uniform stiffness in MC model.The hardening Modified Cam-Clay model(MCC model)and Hardening Soil model(HS model)reasonably distinguish the stiffness of loading and unloading,thus the results calculated consistent with the actual data.In addition,there is not much difference in the stress of envelope enclosures with the three models.In general,the hardening MCC or HS model is recommended when analyzing the soil deformation resulting from foundation pit excavation.