岩质高边坡的地震时程响应分析

Seismic Time-history Response Analysis of High Rock Slopes

针对白鹤滩水电站右岸进水口反倾向层状结构岩质高边坡,采用3DEC程序建立了非连续介质模型,在静力分析的基础上,进行了Ⅷ度地震的动峰值加速度0.212 g的时程响应分析.数值模拟结果表明,边坡中上部岩体的动力响应较为强烈,表现出动力反应的"鞭梢"效应,并且岩体变形受控于结构面,表现出明显的不连续变形特征.而由关键点的时程曲线可见各监测点位移趋于收敛,未见块体的滑移、分离、失稳、破坏迹象;根据莫尔-库仑准则推导的动力条件下的点抗剪安全系数也略大于静力条件下的安全系数,边坡有较大的安全裕度.研究工作说明,边坡动力分析都应以静力分析为基础,且须强调针对结构面控制型问题采用非连续介质力学的分析方法.

The intake slope of right bank of the Baihetan Hydropower Station has structure-controlled stability problems. A noncontinuous model of the slope is built by using the program 3DEC. Based on the static analysis, seismic time-history response behavior for the high rock slope to anti-seismic against M8 earthquake, with 0.212 g peak acceleration, is analyzed. Simulation results show that the upper slope has more strongly response to seismic shock, showing dynamic response of whiplash effect. Rock deformation is controlled by structures, showing discontinuous deformation characteristics. While all monitoring points displacements tend to convergence, no block shows slip, separation, instability or destruction evidences. Moreover, based on the Mohr-Coulomb criterion, safety coefficient under the condition of seismic shock is derived by calculated the shear point slightly safety factor. Since dynamic safety coefficient is greater than the static one, the high slope is deemed to have more safety stock. Research shows that dynamic stability analysis of rock slope should be based on the static analysis, especially, the noncontinuous method should be used for structure-controlled problems.