重力坝坝踵裂缝水力劈裂耦合分析

大坝运行期间，重力坝坝踵裂缝在较高水头作用下易发生水力劈裂破坏。建立扩展有限元法框架下重力坝坝踵裂缝水力劈裂耦合数值模型，并采用扩展有限元法模拟水力劈裂耦合作用下重力坝坝踵裂缝扩展过程。计算结果表明:重力坝坝踵初始裂缝逐渐向坝基底部扩展，且裂缝扩展方向朝向下游；无水力劈裂作用下的裂缝开裂角大于水力劈裂作用下的，无水力劈裂耦合作用下的裂缝开裂角小于水力劈裂耦合作用下的；重力坝坝踵裂缝扩展前，裂缝内水压力基本与边界水压力相同，当裂缝开始扩展时，裂缝内水压力会降低，而后裂缝张开宽度不断增大，裂缝内水压力又会变成边界全水头；裂缝水力劈裂导致裂尖Ⅰ型应力强度因子增大，降低了重力坝裂缝的稳定性。研究结果可为重力坝坝踵裂缝水力劈裂防治提供理论依据。

Coupling analysis of hydraulic fracturing of crack in the heel of gravity dam

The cracks in the heel of gravity dam usually bear the action of high water head during the operation of the dam, which is prone to hydraulic fracturing failure. In this paper, the crack hydraulic fracturing coupling numerical model of gravity dam under the framework of extended finite element method is established, and the crack propagation process of gravity dam heel under the coupling of hydraulic fracturing is simulated by extended finite element method. The calculation results show that the heel of the gravity dam initially gradually extends to the dam base, and the crack propagation direction is towards the downstream. The crack angle without hydraulic fracturing is larger than that under hydraulic fracturing, and the crack angle without hydraulic fracturing coupling is smaller than that under hydraulic fracturing coupling. Before the crack propagation in the heel of gravity dam, the water pressure in the crack is basically the same as the boundary water pressure. When the crack begins to expand, the water pressure in the crack will drop, and then the crack opening width will continue to increase, and the water pressure in the crack will become the boundary full head. Hydraulic fracturing of cracks leads to the increase of type I stress intensity factor at the crack tip and reduces the stability of cracks in gravity dam. The research results provide an important theoretical basis for the hydraulic fracturing prevention of cracks in the heel of gravity dam.