一种实现复杂初始地应力场精确平衡的通用方法

初始地应力场是岩体工程结构有限元分析的重要初始条件,为了实现初始地应力场平衡,传统做法是在计算模型上施加与之相平衡的外荷载(体力、边界力),但外荷载往往组成复杂甚至不可知,且施加边界荷载所要求的模型边界条件通常与初始地应力平衡后结构计算分析所要求的模型边界条件不一致,这就为初始地应力场平衡带来了困难.为此,本文提出了一种可以实现复杂初始地应力场精确平衡的通用方法,该方法的基本思路是直接在有限元计算模型中施加结点荷载来与初始地应力场进行平衡,从而完全避免了由于外荷载的不可知以及边界条件不一致性所带来的困难;此外,由于所施加结点荷载是直接由初始地应力场通过单元积分计算出来的,故可实现初始地应力场的精确平衡.算例分析表明,所提出的方法不仅简便易行,且精度很高,是一种实现复杂初始地应力场平衡的通用方法.

A General Method for the Accurate Equilibrium of Complex Initial In-situ Stress Field

The initial in-situ stress field is an important initial condition for FEM analysis of rock engineering. According to the traditional method, the appropriate volume and surface loads field should be exerted on the FEM model in conjunction with the input of initial in-situ stress for the equilibrium of complex initial in-situ stress field, but the equilibrium is usually difficult as the composition of external loads are complex and even not known, and the corresponding boundary conditions are always not in conjunction with the following anal- ysis. In this paper, a general method for the accurate equilibrium of complex initial in-situ stress field is pro- posed through directly exerting load on nodes to achieve the equilibrium of complex initial in-situ stress field, and the difficulty of the unknown boundary conditions and the Inconsistent boundary conditions can be com- pletely avoided in the proposed method. In addition, due to the node load is directly calculated through the in- itial in-situ stress field, so the accurate equilibrium of complex initial in-situ stress field is achieved. The results of an example show that the proposed method is a general method for the equilibrium of complex initial in-situ stress field, and the method is convenient to implement and has a high precision.