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为研究河谷地形对深厚覆盖层中防渗墙应力、变形的影响,以某沥青混凝土心墙堆石坝为工程背景,模拟了狭窄河谷和宽深河谷并分别建立有限元模型,坝体材料及覆盖层采用邓肯-张E-B模型,防渗墙与覆盖层、基岩之间的接触关系采用无厚度接触面模拟,进行三维非线性有限元计算,对比分析两种河谷情况下防渗墙的应力、变形情况。计算结果表明:狭窄河谷中,防渗墙沉降和水平向位移及防渗墙与覆盖层的不均匀变形均比宽深河谷小,其中不均匀变形最大减小了24.8%;宽深河谷中,防渗墙受河谷地形约束作用较弱,竖直向压应力较狭窄河谷更大,最大增加了40.3%;防渗墙的竖直向压应力最大值位置受中性点位置和河谷地形的共同影响,其中竖直向压应力最大值约30%来自墙顶坝体土压力,70%来自与覆盖层之间的负摩擦力。其研究结果可为不同地形条件下坝基防渗墙的设计提供参考。
In order to study the influence of valley topography on the stress and deformation of impervious wall in deep overburden, taking a certain asphalt concrete core rockfill dam as an engineering background, the narrow valley and wide valley were simulated and the finite element models, The covering layer adopts Duncan-Chang EB model, the contact between impermeable wall and overburden and bedrock, and adopts non-thickness contact surface simulation to carry out three-dimensional non-linear finite element calculation to compare the stress of anti-seepage wall under two kinds of river valleys , Deformation situation. The results show that the settlement and horizontal displacement of impervious wall and the uneven deformation of the impervious wall and the overburden are all smaller than those in the broad and deep valleys in the narrow valleys, and the non-uniform deformation decreases by 24.8% at the maximum. In the broad and deep valleys, The impervious wall is constrained by the terrain of the valley, the vertical compressive stress is larger than that of the narrow valley, with the maximum increase of 40.3%. The maximum vertical compressive stress of the cut-off wall is affected by the neutral point position and valley topography , Of which the maximum vertical compressive stress is about 30% of the earth pressure from the wall dam and 70% from the negative friction with the overburden. The results of this study can provide reference for the design of dam foundation impervious wall under different topographic conditions.