岩体抗剪强度参数现场测试新方法及工程应用

岩体抗剪强度参数的确定是进行岩体工程稳定性分析中最基本和最重要的,也是最困难的一项工作。由于室内和现场试验方法的局限性以及经验准则的人为性,快速、简易和较可靠确定岩体抗剪强度参数的原位测试手段一直是岩石工程界关注的热点。采用引进美国生产的岩石钻孔剪切仪,在实验室混凝土空心圆柱体和向家坝水电站坝基岩体中进行了尝试,取得了有益的试验成果。将主要从钻孔剪切仪的工作原理、数值模拟分析和工程应用等几方面对其进行全面的阐述和总结。试验成果和数值分析结果显示,岩石钻孔剪切仪是一种适用于软岩～中硬岩的原位试验设备,其试验成果总体钻孔剪切试验得到的c、ψ小于传统三轴和直剪试验成果,但钻孔剪切试验的ψ值在ψ<40°的范围内略低于传统三轴和直剪试验成,而钻孔剪切试验的c值较传统三轴和直剪试验的c值降低较多,一般为25%～50%。

An in-situ method for determining shear strength parameters of rock masses and its applications

The shear strength parameters of rock masses are generally most important and difficult to determine when performing stability analysis of rock works. Due to a large number of limitations existed in laboratory and in-situ experiments and uncertainties of empirical methods display, there has been a strong need to develop a new in-situ testing apparatus that can measure the shear strength parameters of rock masses in a quick and reliable way. Since a Rock Bore Shear Tester (RBST) made by Handy Geo. Instruments, Inc. was introduced by IWHR, a large number of laboratory and in-situ RBST experiments have been performed. The shearing mechanism, numerical simulation of RBST shearing process and its applications to Xiangjiaba dam site are presented. It can be found from the numerical analysis and in-situ testing results that RBST is applicable to soft and intermediate hard rock masses. The cohesion and friction angle determined by RBST are generally less than those determined by tri-axial and direct shear tests. In addition, the interal friction angle determined by RBST is a little less than that determined by triaxial and direct shear tests when <40?; and the cohesion c is considerably less than that determined by triaxial and direct shear tests by 25%-50%.