岩体分级BQ与RMR的关系及其力学参数估计

在国标《工程岩体分级标准》（GB50218—94）岩体质量分级的基础上,提出了岩体基本质量指标BQ的简化计算方法。根据规范中建议的岩体物理力学参数取值范围,编制了各参数与BQ关系曲线图,通过非线性拟合分析,建立了各物理力学参数与BQ之间关系的经验公式。基于内摩擦角等效原则,通过比较已有的分别用RMR和BQ表达的岩体内摩擦角经验公式,推导出1个BQ和RMR之间的关系方程。同样基于变形模量等效原则,通过比较已有的分别用RMR和BQ表达的岩体变形模量经验公式,推导出4个BQ和RMR之间的关系方程。这5个关系方程与实测结果进行了比较分析,得到了上限线和下限线方程；由内摩擦角等效获得的关系方程趋势较好,取上限线和下限线的中间线对其进行修正,得到了本文建议的RMR和BQ之间的关系方程。

Relationship between RMR and BQ for rock mass classification and estimation of its mechanical parameters

On the basis of rock mass quality classification in China's national standard, Standard for Engineering Classification of Rock Masses (SECRM, GB50218—94), a simplified calculation method for the basic quality index (BQ) of rock mass is proposed. According to the value ranges of various physical mechanical parameters of rock mass in SECRM, the graphs of the relationship between various parameters and BQ are established. Empirical formulas for the relationship between various parameters and BQ are established using the nonlinear fitting analysis method. Based on the equivalent principle of internal friction angles, through comparing the existing equations for describing internal friction angles using BQ and RMR respectively, a relation equation between RMR and BQ is derived. Similarly, based on the equivalent principle of deformation modulus, through comparing the existing equations for describing deformation modulus using BQ and RMR respectively, four relation equations between RMR and BQ are derived. By comparing five relation equations between RMR and BQ with the existing the field test data, the equations for the upper limit and the lower limit lines are found. The results show that the relation equation obtained using the equivalent internal friction angle has good trend, but its value is a little larger, and a correcting relation equation between RMR and BQ is suggested by means of taking medium line between the upper limit and the lower limit lines.