库水浸泡下全-强风化千枚岩桥基岸坡稳定性分析

Study on Bank Slope Stability of Fully-Strongly Weathered Phyllite Bridge Soaked in Reservoir Water

全—强风化千枚岩具有极强的水敏感性,在库水浸泡后岩体物理力学特性不可避免地存在劣化的趋势,对岸坡的稳定性极其不利。鉴于此,以某全—强风化千枚岩桥基岸坡为研究对象,通过野外详细调查、室内物理力学试验以及Geo-Slope软件分析,考虑水库蓄水对岸坡千枚岩抗剪强度的劣化效应,计算得到该桥基岸坡稳定性的变化规律。结果表明:在水库蓄水后短时间内全—强风化千枚岩抗剪强度参数及岸坡安全系数降低幅度较大,后逐渐减缓;水库蓄水后,黏聚力的劣化幅度比内摩擦角大,黏聚力的水敏感性更强;计算得到在浸水95 d后,安全系数为1.189,小于1.200,处于欠稳定状态,提出岸坡加固建议措施。

Fully-strongly weathered phyllite has strong water sensitivity,and the physical and mechanical properties of the phyllite will inevitably deteriorate after it is soaked in reservoir water,which is extremely unfavorable to the stability of the bank slope.In view of this,taking the bank slope of a fully-strongly weathered phyllite bridge as the research object,this paper carries out detailed field investigations,indoor physical and mechanical tests,and Geo-Slope software analysis,considers the effect of reservoir water storage on the deterioration of the shear strength of the phyllite on the bank slope,and calculates the variation law of the stability of the bank slope of the bridge.The results show that the shear strength parameter and the safety factor of the bank slope of the fully-strongly weathered phyllite decrease greatly within a short time after the reservoir is impounded,but the decrease then gradually slows down.In addition,after the reservoir is impounded,the deterioration of cohesion is larger than that of the angle of internal friction,and the water sensitivity of the cohesion is stronger.When the bank slope is soaked in water for 95 days,the safety factor is calculated to be 1.189,which is less than 1.200 and indicates an under-stable state.Therefore,measures to reinforce the bank slope are proposed.