深基坑大变形耦合分析与数值模拟

Couple analysis and numerical simulation of large deformation of deep foundation pit

深基坑开挖的时空效应既与深基坑工程支护设计、施工方案有关,又依赖于场地岩土介质的工程特性。依据Biot固结理论与有限变形的理论基础,采用经典的变分原理方法推导了基于大变形Lagrangian描述的U. L方法——Biot固结理论耦合系统方程及其有限元数值模拟方法。根据工程实例进行大小变形计算的比较以及深基坑开挖的时空效应分析,得出开挖时空效应显著、小变形计算的安全性不足的结论。

Time-space dependent effect in process of excavating deep foundation pit is in close relationship with the design of support structure and construction sequence and organization but is mostly dependent on engineering behaviors of soil on site. According to Biot抯 consolidation theory and large deformation theory, a coupled model and the method of FEM numerical simulation can be derived with classical variation principle, which is based on Updated Lagrangian formulation of large deformation, As for a real example of engineering, the comparison of the computing results between large deformation and small deformation is shown; and time-space dependent effect of excavating deep foundation pit is analyzed. It is the main conclusion that time-space dependent effect in process of excavation is remarkable and the security of pit using small deformation method is lack.