基于地质强度指标与区间理论的岩体抗剪强度确定方法

Method for determining rock mass shear strength based on interval theory and geological strength index

针对采用结构面表面特征与岩体结构的定性描述确定岩体地质强度指标(GSI)时存在主观性较强的特点,首先,以结构面表面等级(SCR)、节理特征系数(Jc)、岩体结构等级(SR)与岩块体积(Vb)分别对其进行取值量化,并根据量化指标取值过程中所具有的不确定性,采用区间数表示参数取值,在探讨各量化指标取值方法基础上建立岩体GSI区间数确定方法;其次,根据Hoek-Brown准则等效岩体抗剪强度参数转换关系,采用区间组合法进行求解,进而建立出基于区间理论与GSI的岩体抗剪强度确定方法;最后,将其用于湖南省某水电站进水口隧道岩体抗剪强度确定,与现有分析方法对比表明,该方法具有一定的合理性与可行性。在试验资料不足的情况下,该方法为岩体抗剪强度参数确定提供了一条新途径。

The method for determining the geological strength index （GSI） with the surface condition and structure of rock mass mainly depends on their qualitative descriptions. There is much more subjectivity because the value is hard to get through the qualitative description. So, the quantitative indices are firstly used to determine GSI, such as process surface condition rate （SCR）, joint condition coefficient （de）, surface rate （SR） and quantitative block volume （Vb）. SCR and Jc are used to reflect the surface condition. SR and Vb are used to reflect the structure of rock mass. In order to reflect the uncertainty of the quantitative indices, interval values are used to express them. Then the method for determining the interval values of GSI can be presented through the study of the determination of quantitative index values. Secondly, the interval combination method is presented to calculate the rock mass shear strength parameters according to the Hock-Brown strength criterion. And the method for determining rock mass shear strength parameters based on interval theory and GSI is suggested. Finally, the method is used to determine the shear strength parameters of a hydropower station water intake tunnel in Hunan province. Compared with the existing analysis method, the results show that the method is reasonable and feasible. It provides a new approach to determine the shear strength parameters of rock mass, when the test data are less.