两种本构模型的土石坝应力变形分析比较

A Comparison of Two Constitutive Models in Stress and Deformation Analysis of Earth Rockfill Dams

分别利用邓肯-张模型与椭圆—抛物双屈服面模型对深厚覆盖层上的狮子坪心墙堆石坝进行了应力变形三维有限元计算,分析了两种本构模型应力变形计算结果的差异。结果表明,两种模型计算的坝体变形和应力分布规律基本一致,但也存在一些差异。双屈服面模型计算的坝体最大沉降比邓肯-张模型结果小2.2%。双屈服面模型计算的最大顺河向水平位移与最大竖向沉降之比为0.22,与已有多个工程监测资料比较接近,而邓肯-张模型结果则偏大,为0.37。采用心墙拱效应系数R来对心墙拱效应进行评价,结果显示邓肯-张模型计算的心墙拱效应更强烈。邓肯-张模型计算的上游坝壳小主应力降低更显著,但均未出现拉应力。

The three-dimensional finite element analysis of stress and deformation for Shiziping Core Rockfill Dam constructed on the deep overburden layer,was performed by Duncan-Chang and ellipse-parabola double yield surface models respectively. The differences of stress and deformation calculation results between the two constitutive models are analyzed. The results show that the distribution of dam deformation and stress is roughly similar to the two models. But some differences still exist. The maximum dam settlement calculated by double yield surface model is 2.2% smaller than that calculated by Duncan-Chang model. The ratio of maximum horizontal displacement along the river to maximum settlement is 0. 22 for double yield surface model,which is close to some existing engineering monitoring data,while that by Duncan-Chang model is slightly larger,namely 0.37. The core arching effect coefficient R is adopted for the evaluation of core arching effect.It shows that core arch effect calculated by Duncan-Chang model is stronger. The decrease in minor principal stress in the upstream dam shell is more notable for Duncan-Chang model,but no tension stress appears.