基于原位试验和规范的岩体抗剪强度与Hoek-Brown准则估值比较

 简要论述目前岩体抗剪强度确定方法，以黄河上游玛尔挡水电站坝基岩体为例，在岩体质量分级基础上，引入规范建议值及现场原位大型剪切试验结果，建立岩体抗剪强度指标与BQ岩体质量分级的相关关系。同时利用实测资料建立BQ与GSI的相关关系，运用Hoek-Brown准则估算各试验点岩体的抗剪强度指标。结果表明，采用该研究成果较符合工程实际，而采用Hoek-Brown准则估算的等效内摩擦因数偏小，黏聚力则偏大很多。误差分析表明，这一结果主要是由Hoek-Brown准则中最小主应力的取值范围引起的，据此提出公式应用中需注意的问题及相应解决方法。

DETERMINATION OF ROCK MASS SHEAR STRENGTH BASED ON IN-SITU TESTS AND CODES AND COMPARISON WITH ESTIMATION BY HOEK-BROWN CRITERION

Approach of determining shear strength of rock mass at present is briefly reviewed.Taking Maerdang hydropower station located in the upstream of the Yellow River for example,the relationship between shear strength and BQ rating is built up on the basis of rock mass classification,suggested shear strength by codes and in-situ large scale shearing test;and the relationship between BQ rating and GSI is also created according to field survey and measurement.Based on these,shear strength of rock mass at in-situ test point is estimated by Hoek-Brown criterion.The result shows that rock mass shear strength derived from this paper s method is coincident with practical situation;while equivalent fraction coefficient from Hoek-Brown criterion is lower than test value and cohesion force is far greater than that from shearing test.It is shown by error analysis that the difference between experiment values and estimated ones is mostly induced by the span of minimum principal stress used in Hoek-Brown criterion.For this situation,some cautions and corresponding resolve methods while using Hoek-Brown criterion are reminded.