高拱坝坝肩裂隙岩体的三维非线性抗震稳定性分析

Three dimensional nonlinear seismic stability analysis of abutment jointed rock mass of high arch dam

在高拱坝坝肩裂隙岩体的抗震稳定性分析中 ,采用传统刚体极限平衡法分析坝肩裂隙岩体潜在滑体的安全性态 ,坝肩稳定性评价未考虑裂隙岩体变形对坝体应力的影响 ,由此计算的抗滑安全系数并不能保证坝体的安全性 ;而采用基于连续介质理论的有限元法和基于碎散介质的离散单元法分析时 ,其物理数学模型和坝肩岩体的实际情况相距甚远。为此 ,本文在安全系数强度储备概念基础上提出了动抗滑变形安全系数法 ,该方法以坝体拉应力作为坝肩岩体抗滑稳定性评价标准 ,综合考虑非线性坝体和坝基节理、裂隙岩体的动静态耦合作用 ,坝肩岩体的抗滑安全系数保证了坝体的安全 ,较传统的分析方法更为科学、合理。采用该方法 ,本文将坝肩裂隙岩体作为可以考虑局部开裂、各向异性和大变形的非线性连续体用动态接触单元模型模拟 ,对在建的小湾高拱坝坝肩裂隙岩体的抗震稳定性进行了三维动力分析。数值分析结果表明 ,在综合考虑坝体应力影响后 ,坝肩裂隙岩体的变形安全系数小于强度安全系数。因此 ,在高拱坝坝肩岩体的抗震稳定性评价中必须计及坝体应力的影响因素。

The aseismatic stability of abutment jointed rock mass is the key problem of high arch dam.With the application of the rigid body limit equilibrium method(RBLEM),the stresses in high arch dam are not considered when the seismic stability of abutment jointed rock mass is evaluated, so the safety coefficient calculated by RBLEM does not assure the safety of dam. According to the mechanical principle of intensity repertory the method of dynamic deformation safety coefficient of abutment rock mass is employed in order to take into consideration the safety of arch dam itself. In this paper, two different approaches,i.e.,dynamic deformation safety coefficient method and dynamic intensity safety coefficient method, are used to study the seismic stability of abutment of Xiaowan arch dam with the maximum height H=292 m. And the foundation rock of the abutment is considered as continuous medium with characteristics of nonlinear large deformation and cracking. The numerical results of Xiaowan high arch dam indicate the rationality and the feasibility of the proposed method.