深基坑工程土壤参数之反分析

Inverse analysis of soil parameters for deep excavation engineering

土壤本构模型及输入参数是影响有限单元法深基坑工程分析结果的关键。采用非线性优化方法和两种土壤本构模型,利用一个台北盆地实际的深基坑工程案例反分析土壤参数,结果显示,优化方法可以根据现地监测数据,反分析出代表深基坑工程行为的土壤参数。两种土壤本构模型对开挖所引致的支护结构侧向位移均有良好的模拟。考虑土壤小应变的土壤本构模型,反分析所得的土壤初始劲度参数值,较接近现地不扰动土样初始劲度试验结果,也较能合理的预测深基坑工程开挖所引致的地表沉陷。

Both soil models and input parameters are important factors affecting the results of deep excavation analysis using the finite element method.This study adopts a nonlinear optimization method and two soil models to conduct the inverse analysis for back-figuring soil parameters in a practical excavation case history.The results show that the optimization method is capable of back-figuring the representative soil parameters of deep excavation engineering based on the in-situ observations. The braced excavation-induced lateral wall deflections can be well simulated by the two soil models.The initial stiffness of soils back-figured by the soil model capable of describing small strain behavior is closer to that obtained from the laboratory tests with the undisturbed soil samples than the soil model without considering the small strain behavior.Also,the deep excavation-induced ground surface settlement can be more reasonably predicted by the small strain soil model.