网格尺寸对拱坝等效应力分析的影响

本文对有限元内力法求解拱坝等效应力分析方法进行了进一步改进。建立了拱梁向应力为直线分布时以上、下游面等效应力为未知量而拱或梁截面上的约束内力为已知量的求解方程，并根据常规的多拱梁应力分布假定及上、下游面已知应力边界条件，导出了上、下游面其余应力分量求解公式。对溪洛渡高拱坝在水压力(含淤砂压力)、温升、温降及自重等荷载作用下不同网格的计算结果表明，拱厚方向采用两层以上单元、拱梁方向网格采用足够精度的网格可得到基本稳定的等效应力结果。

Effect of mesh size on analysis of arch dam equivalent stress

The finite element internal force method for calculating arch dam equivalent stress is improved. The equation for calculation is established based on the assumptions that the stress is linearly distributed in the arch-beam direction, the equivalent stress on the upstream and downstream surfaces are unknown variable and the constraint internal force in the cross section of arch or beam is given. The formulas for calculating other stress components at the upstream and downstream surface of the dam are deduced when boundary conditions are given. The calculations for Xiluodu arch dam under the actions of water pressure (including the pressure of sedimentation), temperature variation and self weight with different sizes of mesh shows that the stable equivalent stress distribution can be obtained when 2 elements in radial direction, 10 elements in arch direction and 19 elements in beam direction are adopted.