金沙江鲁地拉水电站混凝土重力坝地震抗滑稳定性的时程法分析

通过动力有限元时程法分析了金沙江鲁地拉水电站碾压混凝土重力坝在设计地震动作用下的动态响应,计算模型考虑了大坝–库水相互作用、大坝–岩基相互作用,用黏弹性吸波边界模拟了地震动能量向无限远域逸散的地基"辐射阻尼"效应。利用质点系"达朗贝尔原理"计算得到了坝体地震惯性力时程,通过将坝体惯性力时程极大值与振型分解反应谱法的惯性力计算值对比,验证了复杂地震动力数值计算结果的正确性。在坝体惯性力时程基础上叠加其它静力荷载,计算得到了大坝沿建基面的瞬态抗滑安全系数时程。计算结果表明:鲁地拉重力坝在设计地震动(0.36g)作用下的安全系数时程的极小值大于规范规定值,大坝整体抗震稳定性良好,不必采取提高整体抗滑稳定性的工程加固措施。作为典型重大工程实例研究,采用的动力计算方法对类似大坝工程的抗震计算具有参考意义。

Time-history analysis of seismic sliding stability for RCC gravity dam of LudiLa Hydropower Station,Jinshajiang River

The dynamic finite element time-history analysis method is employed to compute the seismic response of Ludila RCC gravity dam at Jinsha River subjected to design earthquake loading (0.36g). The dam-water-foundation interaction and the foundation radiation damping effect of the seismic energy dissipating towards infinite domain are considered in the FEM model. The time histories of inertial force of the dam are calculated by using the D'Alembert's principle of particles system. Then, the time histories of the sliding safety factor of the dam along dam-base sliding interface can be obtained by combining the inertial force and other static loads. The complex earthquake numerical simulation results are validated by comparing the inertial forces of the dam calculated by the time-history analysis method and the spectrum method. Because the minimum value of safety factor satisfies the requirements of the seismic design code of hydraulic structures, it can be concluded that the overall seismic stability of Ludila Dam is good, and the reinforcement to improve the anti-sliding stability is not needed. The proposed method should be of interest and useful to professionals involved in the seismic design of large gravity dams.