谷竹高速公路原状片岩抗剪强度的水敏性研究

Study of shear strength watersensitivity of intact schist from Guzhu expressway

为了解鄂西北地区水敏性片岩在水作用下的抗剪强度特性,对取自谷竹高速公路现场的原状片岩试样开展了沿其层理面的室内天然状态直剪试验和饱水状态直剪试验,试验结果表明:水对片岩的抗剪强度和破坏特征影响显著;饱水后片岩与天然状态相比凝聚力降低了36.7%,内摩擦角降低了4.6%,残余凝聚力降低了66.7%,残余内摩擦角降低了11.3%;与天然状态的脆性破坏不同,饱水后片岩破坏时具有明显的延性特征。基于试验结果,探讨了水对片岩抗剪强度参数的弱化机制,利用极限平衡方法计算了谷竹高速公路沿线某边坡的安全系数,进而对该边坡在暴雨或连续降雨工况下的稳定性做出了评价。

Shear tests along bedding plane on Guzhu expressway schist under natural state and water-saturated state have been carried out in order to analyze the shear strength characteristics of the water-sensitive schist located in northwest of Hubei province under the two states.The results show that：compared with the native state,the cohesion force of the schist under saturation state decreased by 36.7%;the internal frictional angle decreased by 4.6%;the residual cohesion force decreased by 66.7%;the residual internal frictional angle decreased by 11.3%;it is different from the brittle fracture under natural state that the schist shows obvious characteristic of ductility at failure under saturation state.Based on the experimental results,the water weakening mechanism of shear strength parameters of schist has been discussed;a safety factor of a slope located in Guzhu expressway has been computed with limit equilibrium method;and then the evaluation of the slope stability under storm or continuous rainfall conditions has been made.