重力坝应力分析中扬压力的施加方法研究

Exerting Method of Uplift Pressure in Gravity Dam Stress Analysis

研究了采用有限元法进行重力坝应力分析时扬压力的施加方式不同对坝体应力值及其分布的影响。基于重力坝为静定结构、水平截面上不同分布方式的应力的合力相等的原则,采用有限元法对比分析了扬压力作为面荷载作用在坝基面,以及将扬压力沿坝基面向上对折作为体力考虑两种情况下水平截面上的应力分布和合力,然后与材料力学法计算的水平截面上的合力进行对比。分析认为,采用有限元法进行重力坝应力分析时,将扬压力沿坝基面向上对折作为体力考虑时,其计算的水平截面的内力与材料力学法计算的截面内力接近;但在靠近坝基面附近1/3坝高范围内的垂直向正应力和剪切应力分布不一样,另外,水平向正应力分布差异较大。

This paper studied the exerting method of uplift pressure when adopting the FEM to analyze the stress for gravity dam. Based on the prin-ciple that,gravity dam is statically determinate structure and different exerting methods have the same resultant force,adopted the FEM to do a con-trastive analysis about the stress distribution and the resultant force in two cases,setting the uplift pressure as face load on the foundation surface and folding up uplift pressure along foundation surface as the buoyancy,and then,compared with the resultant force that calculated by materials mechanics. The analysis shows that when adopting the FEM to do the stress analysis,folding up the uplift pressure as buoyancy,the calculated in-ternal forces approach to the forces that calculated by material mechanics. While the distributions of normal stress in vertical and the sheer stress are different within 1 / 3 dam height near the foundation surface,in addition distributions of normal stress in horizontal are quite different.