拱坝有限元三次等效应力计算方法与控制标准

针对现行拱坝规范中的有限元等效应力法假设应力沿径向线性分布,与拱坝实际应力分布不符的问题,基于最小二乘法采用三次多项式拟合拱坝主要应力分量,提出了拱坝三次等效应力计算方法。对小湾拱坝进行的网格敏感性分析表明,随着计算网格的加密,三次等效应力可收敛到稳定解,据此给出计算拱坝三次等效应力的有限元模型单元剖分方案;对比分析了4座已建拱坝的三次等效应力与线性等效应力后,提出了拱坝三次等效应力控制标准。

Calculation Method and Design Criterion of Cubic Equivalent Stress for Finite Element Analysis of Arch Dam

In recent design specification for concrete arch dams, it is assumed that the finite element equivalent stresses linearly distribute along the radial direction. This assumption is not consistent with the actual stress distribution of arch dam. In this paper, cubic polynomial was used to fit the main stress components by least square method, and a cubic equivalent stress method was proposed for FE analysis of arch dam. Taking Xiaowan arch dam as an example, mesh sensitivity analysis was performed, and it indicated that the cubic equivalent stresses can converge to the stable values with increase of mesh numbers. Based on this analysis, a meshing scheme of FE model was proposed for the calculation of arch dam cubic equivalent stress. By comparing the cubic equivalent stress and linear equivalent stress in 4 existing arch dams, the control criterion of cubic equivalent stress was carried out for arch dam design and safety evaluation.