两种常用本构模型在基坑开挖数值模拟中的适用性

Applicability of two constitutive models to numerical simulation of foundation excavation

针对基坑分析中难以选择土体宏观本构模型的现状,通过数值模拟研究2种常用本构模型对基坑开挖问题的适用性。首先,基于双轴压缩试验,求解与离散元试样在力学特性上相匹配的M-C和D-P模型参数;其次,进行基坑开挖模拟,以离散元的应力、应变路径分析结果为参考,讨论2种本构模型在基坑分析中的特点及适用性。结果表明:M-C和D-P本构模型能够较好地反映开挖过程中土体的复杂应力发展,难以表征土体的变形发展;2种模型的基坑开挖分析结果相差不大。

It is difficult to select an appropriate constitutive model for numerical simulation of foundation excavation problems.The applicability of two commonly used constitutive models to foundation excavation was examined through numerical simulation in this study.First,the biaxial compression test was conducted using the discrete element method（DEM） and the finite difference method（FDM） that incorporates the Mohr-Coulomb（M-C） model and Drucker-Prager（D-P） model.The model parameters were obtained by fitting the stress-strain curves and the volumetric strain-axial strain curves that were captured by the DEM simulation.Second,using the model parameters,excavation of a foundation pit was simulated by DEM and FDM.Finally,the DEM results of the stress path and strain path were used as the reference for evaluation of the performance and applicability of the M-C model and D-P model.The results show that the two models can accurately capture the stress path during excavation,but cannot describe the accumulation of deformations in soils,and there is not much difference between the two models’ results.