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通过动力有限元时程法分析了金沙江阿海混凝土重力坝在设计地震动(0.344g)作用下的动态响应,计算模型考虑了动水压力作用、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。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极值对比,从而验证了复杂动力数值模拟结果的正确性,为后续分析打下了基础。采用沿滑面的应力积分法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:阿海重力坝在设计地震动(0.344g)作用下的安全系数时程的极小值为1.146,大坝整体稳定性良好,可不采取提高整体抗滑稳定性的工程加固措施。作为重大工程典型实例研究,采用的计算方法和所得结果对类似大坝工程抗震研究具有参考意义。
The dynamic response of the Ahai concrete gravity dam of Jinsha River under the design ground motion (0.344g) was analyzed by dynamic finite element time-history method. The calculation model considered the interaction of hydrodynamic pressure, dam-foundation interaction and the viscoelasticity The wave absorbing boundary simulates the “radiative damping” effect of ground motion energy dissipated to infinity. By comparing the maximum moment of inertia of dam body with the extreme value of inertia force of mode decomposition response spectrum method, the correctness of complex dynamic numerical simulation results is verified, which lays the foundation for subsequent analysis. Adopting the stress integral method along the sliding surface, the time history of the transient anti-sliding safety factor of the dam along the built surface is obtained. The calculated results show that the minimum value of the safety factor of Ahai gravity dam under design ground motion (0.344g) is 1.146, and the whole stability of the dam is good. It is not necessary to take engineering reinforcement measures to improve the overall stability of the anti-sliding. As a typical example of a major project, the calculation methods and the results obtained are of reference value for the seismic researches of similar dam projects.