广义Hoek-Brown准则中强度折减系数的确定

DETERMINATION OF SHEAR STRENGTH REDUCTION FACTOR FOR GENERALIZED HOEK-BROWN CRITERION

稳定性系数是边坡安全性评价的关键指标,但对适用于岩体特性的Hoek-Brown准则的折减存在标准不统一或计算复杂的特点,有必要确定合适的强度折减方案和系数。将广义Hoek-Brown准则(2002)与强度折减原理相结合,以三峡库区狮子包高边坡为模型,通过改变坡高、坡角和参数,以7种对岩石单轴抗压强度ci、地质强度指标GSI和岩石材料常数mi的简化折减方案,研究狮子包高边坡的稳定性,并对稳定性系数和抗剪强度进行误差分析,确定广义Hoek-Brown准则的最优强度折减方案。研究结果表明,对广义Hoek-Brown准则的强度折减可通过同比折减参数ci和GSI获得,此时数值计算与极限平衡法(Morgenstern-Price)确定的高边坡稳定性系数相对误差平均值为6.9%,方差为6.9%,抗剪强度相对误差为4.98%。这对广义Hoek-Brown准则在岩质边坡稳定性数值计算中的广泛应用有一定理论意义和价值。

Factor of safety is a key indicator and the shear strength reduction method is currently very popular for evaluating rock slope stability. But for reduction technique of the nonlinear generalized Hock-Brown criterion （2002）, the standard is not unified or with complex calculation. Taking Shizibao high rock slope in the Three Gorges area for example, 8 models were established by changing the height, angle and parameters of the slope. And the stability was evaluated by seven reduction technique schemes, which were the combination by reduction of the three parameters, i.e. uniaxial compressive strength of intact rock σci, geological strength index GSI, and material constant of intact rock mi. Then the relative errors of the seven schemes were analyzed; and the shear strength reduction factor was obtained for the generalized Hock-Brown criterion. The result shows that the factor of safety can be obtained by reduction of the two parameters ~i and GSI in the same rate for the generalized Hock-Brown criterion. The factor of safety by shear strength reduction method is similar to that by the limit equilibrium method, Morgenstem-Price. And the average relative error of factor of safety is 6.9%~ the variance is 6.9%： and the shear strength relative error is 4.98%. The result has some theoretical value for the wide application of the generalized Hock-Brown criterion to the rock slope stability evaluation.