基于扩展有限元的混凝土重力坝水力劈裂分析

Hydraulic Fracturing Analysis of Concrete Gravity Dam Based on Extend Finite Element Method

利用扩展有限单元法在求解不连续问题上的独有优势,在裂纹面以水压力方式模拟水力劈裂荷载,以解决裂纹扩展时涉及裂纹面非线性和移动边界问题。针对某待建混凝土重力坝,通过ABAQUS软件建立黏聚力裂纹扩展模型模拟水力劈裂,采用上游超载静水压力模拟高水压作用,研究不同裂纹长度、角度及裂纹面水压力对裂纹扩展的影响。结果表明:在相同初始裂纹夹角和水压作用下,裂纹起裂方向与预置裂纹方向夹角值基本一致;预置裂纹与水平向夹角为45°时,裂纹扩展深度最浅;随着裂纹面水压力数值增大,坝踵预置裂纹逐渐向坝基底部扩展;随着坝体折断面预置裂纹长度的增加,预置裂纹尖端周围应力值逐步增大,坝顶和主裂纹最大张开位移也随之增大,最终形成一条主裂纹并不断地向下游坝基面进行扩展,结构承载能力逐渐降低。

Based on the unique advantage of the extended finite element method in solving the discontinuous problem,the hydraulic splitting load was simulated by water pressure on the crack surface to solve the nonlinear and moving boundary problems of crack propagation.According to a proposed concrete gravity dam,the cohesive crack propagation model was established by ABAQUS to simulate hydraulic fracturing,and the upstream overload hydrostatic pressure was used to simulate the action of water pressure.Then,the effects of crack length,angle and water pressure on crack propagation were studied.The results show that the crack initiation direction is basically consistent with the preset crack direction under the same initial crack angle and water pressure.When the angle between the preset crack and the horizontal direction is 45°,the crack propagation depth is the shallowest.In addition,with the increase of water pressure on the crack surface,the pre-set cracks on the dam heel gradually propagate to the dam base.With the increase of the preset crack length of the dam fracture section,the stress around the preset crack increases gradually,and the maximum opening displacement of the dam crest and the main crack also increases.Finally,a main crack is formed and continues to expand downstream of the dam foundation,the bearing capacity of the structure gradually decreases.