蓄水期大岗山右岸抗剪洞加固及其效果分析

Reinforcement Mechanism and Effectiveness of Anti-shear Galleries in the Right Bank of Dagangshan Hydropower Station in the Process of Reservoir Impoundment

为研究蓄水期大岗山水电站右岸边坡抗剪洞的加固机理和加固效果,首先根据微震监测结果分析了蓄水过程中抗剪洞及周围岩体的微震活动性,圈定了蓄水期右岸边坡内部主要损伤区域;然后利用真实破裂过程分析方法(RFPA)模拟蓄水过程,得到了蓄水过程中边坡的应力场、位移场,对抗剪洞在蓄水过程中的微震活动性作出解释;最后,利用数值模拟方法分析了蓄水过程中抗剪洞的加固作用机理,评价了抗剪洞加固措施在蓄水过程中的加固效果。研究表明:抗剪洞能够提高边坡的抗剪能力,但随着其布设的高程降低,这种加固效果越来越弱;蓄水过程中,抗剪洞表现出了宏观剪切、微观拉裂的破坏形式。

The mechanism and effectiveness of reinforcing the right bank slope of Dagangshan hydropower station by replacing weak zones with anti-shear galleries during water storage are investigated.According to microseismic monitoring,the major damage regions in the right bank slope are identified;microseismic activities concentrates in the vicinity of anti-shear galleries at 1 240 m,1 210 m,1 180 m,and 1 150 m,mainly induced by tention fractures.Moreover,the stress field and displacement field during impounding are obtained by numerical simulation in RFPA(realistic failure process analysis)code to explain the microseismic activities of anti-shear galleries:stress concentration and failure are prone to occur around the anti-shear galleries which is in tension state.In association with the numerical results together with the microseismic-monitoring data,macro-shear and micro-tension are found to be the failure mode of anti-shear galleries.In the early stage of impounding,anti-shear gallery affects the stress distribution in the bank slope,and refrains from penetrative plane of fracture.Meanwhile,anti-shear gallery could enhance the anti-shear ability of bank slope;however such effect attenuates with the decline of elevation.In general,anti-shear galleries are conducive to the stability of bank slope during impoundment.