基于矩法的重力坝建基面非线性等效应力分析

针对重力坝建基面角缘应力问题提出了非线性等效应力的概念。采用多项式表示等效应力,根据等效应力的各阶矩与有限元应力相应的各阶矩相等,确定多项式的系数,进而得到等效应力的分布。分析表明,当前普遍采用的线性化等效应力仅是非线性等效应力在一次矩等效时的特例。重力坝算例说明,2阶等效应力具有一定的网格稳定性,适合在重力坝工程中比较局部角缘应力。

Nonlinear Equivalent Stress Analysis of Base Surface of Gravitvity Dam based on Moment Methods

The concept of nonlinear equivalent stress is proposed in this paper to solve the problem of corner stress of gravity dam near the base surface.The nonlinear equivalent stress is expressed by a polynomial.Given the condition that the moments of equivalent stress should be equal to those of the stress from FEM,the coefficients of the polynomial can be obtained,consequently the distribution of equivalent stress can be achieved.In the framework of this concept,the linear equivalent stress is only a special case of nonlinear equivalent stress when the moment is one-order.The case study of a gravity dam shows that the 2-order equivalent stress is somewhat mesh independent,and suitable to be used to evaluate the corner stress of gravity dams.