中欧规范岩体抗剪强度参数确定方法比较研究

Comparative Study on Determination Methods of Shear Strength Parameters of Rock Mass under Chinese and European Standards

对我国岩体分级常用规范《工程岩体分级标准》(GB/T 50218—2014)中的BQ分级系统与国外岩体地质力学RMR分类方法、巴顿Q系统分类方法进行比较分析,阐明三种方法在岩体分级评价时的评价过程和评价特性;结合国外在建某高铁项目,对项目某段路堑边坡岩体的分级和强度参数进行评价。结果表明:岩体质量分级(BQ)和RMR分类方法为定性与定量相结合的方法,而巴顿Q系统分类方法主要为定性分析方法。三种方法对砂岩夹泥岩岩体评价结果分别为Ⅱ级、Ⅱ级和Ⅲ级,对砾岩夹泥岩岩体评价结果分别为Ⅱ级、Ⅲ级和Ⅲ级。在对路堑边坡岩体强度参数进行评价时,岩体质量分级法(BQ)所得岩体黏聚力与最终采用值相近,而岩体地质力学RMR分类法和巴顿Q系统分类法确定的岩体黏聚力分别为最终采用值1.4~2.7倍和0.4~0.6倍;岩体内摩擦角与最终采用值相比分别偏大8.7%~52.2%、偏小9.4%~43.5%。

A comparative analysis was conducted on the Engineering Rock Mass Classification Standard(GB/T 50218—2014),the BQ grading system commonly used standard for rock mass classification in China,and the RMR classification method for rock mass geomechanics and the Barton-Q system classification method.The evaluation process and characteristics of these three methods in rock mass grading evaluation were elucidated.An evaluation was conducted on the classification and strength parameters of the rock mass of a cutting slope in a section of the high-speed railway project under construction abroad.The results showed that rock mass rating(BQ)and the RMR classification method are a combination of qualitative and quantitative analysis methods.The Barton-Q system classification method mainly uses qualitative analysis.The evaluation results of the rock mass of siltstone interbedded with mudstone using these three methods were respectively GradeⅡ,GradeⅡ,and GradeⅢ.In addition,the evaluation results of the rock mass of conglomerate rock interbedded with mudstone were respectively GradeⅡ,GradeⅢand GradeⅢ.When evaluating the strength parameters of rock mass of cutting slopes,the rock mass cohesion obtained through the rock mass rating method(BQ)was similar to the final value used.However,the rock mass cohesion determined by the RMR classification method and the Barton-Q system classification method are 1.4−2.7 times and 0.4−0.6 times the final value,respectively.The internal friction angle of the rock mass was 8.7%−52.2%higher and 9.4%−43.5%lower than the final adopted value,respectively.