基于Hoek-Brown经验公式的岩体稳定性可靠度分析

Reliability analysis of rock mass stability based on Hoek-Brown empirical formulas

为消除因用Hoek-Brown经验公式的中间变量而导致评估的稳定性概率产生累积误差,提出岩体稳定性可靠度应直接由基本变量入手来评估。简要介绍Hoek-Brown经验公式评估力学参数方法后,根据微元体应力定义了单元安全系数,建立了包含Hoek-Brown经验公式基本变量在内的功能函数。选用了Rosenbleuth点估计法评估单元安全系数的概率特征值,介绍了与有限元法结合计算稳定性可靠度的基本流程。对一开挖边坡稳定性可靠度计算分析表明,计算结果与边坡实际发生的破坏特征一致。建议的方法可方便地用于边坡、地基和地下洞室中岩体稳定性的可靠度评价。

In order to eliminate the accumulative probability errors resulting from the use of the indirect variables in the Hoek-Brown empirical formulas,it is presented that the reliability analysis of rock mass stability should be implemented directly starting with the basic variables of the empirical formulas.On the basis of a brief introduction of the mechanical parameter estimates with the Hoek-Brown formulas,the safety factor of a micro-unit was first defined according to its stress state;and a performance function containing the basic variables of the empirical formula was established.The Rosenbleuth point estimate method was chosen to calculate the mean and standard deviation of the safety factor of element.With the combination of the point estimate and finite element methods,the calculation of the stability reliability of the rock mass was described.The stability analysis of a cut slope shows that the results calculated by the reliability analysis method,are consistent with the occurred failures of the slope.The recommended method is convenient to estimate the stability reliability of slopes,foundations and underground caverns related to the rock mass.