岩体结构面抗剪强度参数的取值研究

Study on Shear Strength Parameters of Rock Mass Structural Plane

通过岩体的完整性系数求解粗糙度系数,运用等效处理JRC-JCS模型法、JRC-JCS模型最小二乘法、JRC-JCS模型力学解法计算比较,三种方法是等效的。其中JRC-JCS模型最小二乘法更适用于求解岩屑型结构面的等效抗剪强度参数。通过与实测值比较,采用等效JRC-JCS模型法时,等效抗剪断摩擦系数与试验值很接近,可直接取值;等效抗剪断凝聚力:1对于无充填的硬质结构面,比实测值偏大,2对于无充填的软质结构面,比实测值偏小。采用等效JRC-JCS模型法时,等效抗剪断凝聚力取值应根据等效JRC-JCS模型法求解的抗剪断摩擦系数应用式(20)计算确定。采用JRC-JCS模型最小二乘法求解岩屑型结构面的等效抗剪强度参数时,可直接取值。对于岩屑夹泥型,可根据岩屑含量和含泥量,分别按有软弱黏土充填情况和有岩屑充填情况分别计算,然后按含量百分比加权平均更合理些。

When the rock integrity coefficient is used for roughness coefficient, through comparing the three methods of JRC-JCS model, JRC-JCS model and its least-square solution, and mechanics solution based on JRC-JCS model with equivalent processing methods, the three methods are equivalent. JRC-JCS model and its least-square solution is more suitable for solving the equivalent shear strength parameters of cutting type structural plane. By comparison with the measured values,when using the equivalent JRC-JCS model, the equivalent shear friction coefficient is very close to the test value and then the value can be directly used, equivalent shear cohesion： （1）for the rigid structure plane without filling the surface,is larger than the measured value. （2）for the soft structure plane without filling the surface, is smaller than the measured value. When using the equivalent JRC-JCS model, equivalent shear cohesion value should be measured by the formula for caculating the shear friction coefficient based on the equivalent JRC-JCS model. Using JRC-JCS model and its least-square solution for the equivalent shear strength parameters of cutting type structural plane, the value can be directly used. For cuttings intercalated with clay, according to the content of rock debris and clay content, it can be caculated respectively depending on the filling of the soft clay or the cuttings and then weighted average is more reasonable according to the percentage.