Rockmass is characterized by non-homogeneous, anisotropic and discontinuous due to the structural plane cutting action, which makes the rockmass strength different from that of the common homogeneous material. In engineering practice, the mechanical parameters of rockmass can only be estimated by in situ test or empirical formula. Tests in situ are costly and difficult to conduct in some areas,thus,it is a good choice to obtain the mechanical parameters of rockmass by empirical formula. Generalized Hoek-Brown strength criterion can well reflect the nonlinear failure characteristics of rockmass by considering many factors such as rock mass structure, rock strength and rockmass disturbance. The mechanical parameters of slope rockmass can be estimated with Hoek-Brown criterion. The generalized Hoek-Brown criterion based on the qualitative GSI system is used to estimate the strength of rock mechanical parameters in the rock slope on the exit of ji-er-mu tunnel,and the results show that the parameters obtained by this method are reasonable. The estimated results of rock mechanical parameters of the main body of the slope on the exit of ji-er-mu tunnel show that the uniaxial compressive strength is 1.5 MPa;the deformation modulus is 3 GPa; the shear strength index C=0.6 MPa and φ=32°. The generalized Hoek-Brown strength criterion is proved more convenient, timely and accurate to reflect the actual situation of rockmass in high and steep slope and has good operability in engineering.Key words: Rock slope; Generalized Hoek Brown's strength criterion; Quantitative geological strength index;Rockmass mechanical parameter%岩体因结构面切割作用而具有非均质、各向异性和不连续性的特性,这使得岩体强度与普通均质材料强度有所区别.工程实践中,岩体力学参数只能通过原位试验或经验公式进行估计.原位试验费钱费力且部分地区无法进行试验,因此通过经验公式获取岩体力学参数是很好的选择.广义Hoek-Brown强度准则考虑岩体结构、岩块强度、岩体扰动等多方面因素,能够很好反映岩体非线性破坏特征,利用该准则可对边坡岩体力学参数进行估计.通过量化GSI的广义Hoek-Brown强度准则估算吉尔木隧道出口边坡岩体力学参数,结果表明:该方法估计获得的参数是合理的.通过计算表明边坡主体部分岩体单轴抗压强度为1.5 MPa,变形模量为4 GPa,抗剪强度指标C=0.6 MPa,φ=32°.广义Hoek-Brown强度准则在高陡边坡岩体参数的估计中能更加方便、及时、准确地反映岩体的实际情况,在工程实践中具有很好可操作性.
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