索风营水电站Dr2危岩体动力稳定分析

Analysis on dynamic stability of Dr2 dangerous rock mass at Suofengying Hydropower Station

针对索风营水电站的Dr2危岩体在地震作用下的动力稳定问题,以及锚固洞、抗滑桩等加固措施在单独、联合作用时对整体稳定的贡献度问题,通过建立包含危岩体及其加固措施的三维有限元模型,采用振型分解反应谱法计算了危岩体上的滑体在地震作用下的惯性荷载,并将其作为外荷载与静力荷载工况进行组合。基于三维非线性有限元强度折减法,以特征点位移突变、锚固洞(或抗滑桩)截面最大剪力超过其典型截面的斜截面极限抗剪承载力等为失稳判据,以此确定危岩体的动力稳定安全系数。结果表明:天然状态下的危岩体动力稳定安全系数为1.017,不满足规范要求。单独考虑锚固洞或抗滑桩加固时,危岩体的动力稳定安全系数分别为1.10、1.06;洞桩联合加固时危岩体动力稳定安全系数为1.11,洞桩联合加固的效果较好。研究成果对同类复杂岩质高边坡的动力稳定分析具有参考价值。

Aiming at the dynamic stability of the Dr2 dangerous rock mass at Suofengying Hydropower Station under seismic action as well as the contributions from the reinforcement measures of anchoring cavern, anti-slide pile, etc. under the conditions of their independent effect and joint effect on its integral stability, the inertial loads of the slide-block on the dangerous rock mass under seismic action are calculated with mode-superposition response spectrum method through establishing a 3-D finite element model for the dangerous rock mass and its reinforcement measures, and then the inertial loads are combined by taking them as the external load and static load conditions. Based on 3-D nonlinear FEM strength reduction method, the displacement mutations at characteristic points, the sectional maximum shearing forces of the anchoring cavern (or anti-slide pile ) which exceed their diagonal section shearing capacities of their typical sections, etc. are taken as the instability criteria, with which the dynamic stability safety coefficient of the dangerous rock mass is determined. The result shows that the dynamic stability safety coefficient of the dangerous rock mass is 1.017 under the natural condition, and then cannot meet the requirement from the relevant specification. When anchoring cavern or anti-slide pile are seperately considered, the dynamic stability safety coefficients of the dangerous rock mass are 1.10,1.06 respectively, while the dynamic stability safety coefficient is 1.11, if the dangerous rock mass is jointly reinforced by both anchoring cavern and anti-slide pile, thus the effect of anchoring cavern and anti-slide pile joint reinforcement is better. The study result has a referential value for the dynamic stability analysis to be made on the similar high complicated rock slope.