高土石坝坝坡抗震稳定分析的研究

Research on slope seismic stability analysis of high earth-rock dams

利用拟静力法进行高土石坝坝坡抗震稳定分析时,地震荷载按照现行《水工建筑物抗震设计规范》(DL5073-1997)建议的土石坝地震加速度动态分布系数图示确定。但是此图示只适用于150m以下的土石坝,而目前许多土石坝的设计高度已远大于150m。与低坝相比,高坝的高阶自振周期与地震卓越周期遇合的机率增大,高阶振型的振动易于被激发放大,从而导致坝体地震加速度沿坝高分布与低坝有所不同。本文采用有限元法研究了高土石坝的加速度分布,提出了250m级高土石坝的地震加速度动态分布系数图示,并以此确定地震荷载,同时利用筑坝材料的非线性强度准则和土体动强度准则,对250m级高土石坝坝坡抗震稳定性作了进一步的讨论。

When the pseudostatic method is employed to analyze the slope seismic stability of high earth-rock dams, the earthquake load is computed according to seismic coefficient figure in the present specifications for aseismatic design of hydraulic structures（DI5073-1997）. The figure is only suitable for earth-rock dams lower than 150 meters. At the present time, many earth-rock dams to be constructed are higher than 150m. Compared with low dams, high order self-vibrating period of high dams gets more opportunities to coincide with seismic predominant period, and vibrations of high orders are easily to be activated and amplified, which result in seismic acceleration distribution is different from low dams. The seismic acceleration distribution of high earth-rock dams is analyzed by finite element method. The figure of seismic coefficient of earth-rock dams of 250m-level in height is put forward, according to which the earthquake load is computed. At the same time, the nonlinear strength criterion of dam materials and dynamic strength criterion of soil are taken into consideration. Based on the above further discussion of slope seismic stability of earth-rock dams of 250m-level in height is made .