岩石考虑中间主应力Hoek-Brown强度参数分析

为了进行深部地下工程稳定性分析，准确建立岩石强度准则，利用考虑中间主应力的Hoek-Brown强度准则，将σ2+σ3作为自变量，σ1-σ3作为应变量，对国外学者所做的7组（白云岩、石灰岩、粗面岩、砂岩、页岩、大理岩和闪岩）真三轴压缩强度试验数据进行了拟合分析。采用多次拟合逼近方法，结合各参数的物理特点，给出了合理的参数取值或计算公式。分析结果表明，对于应力强度比κ介于1.5~8之间的高应力状态，考虑中间主应力Hoek-Brown岩石强度准则（σ1-σ3=σc［m(σ2+σ3)/(2σc)+s］n）与试验较吻合，其中参数n可取0.4，s可取1，m与应力强度比κ之间符合幂函数关系，可用公式m=1.5κ1.8计算。

Parameters in Hoek Brown's failure criterion considering intermediate principal stress of rock

The accurately establishing rock strength criteria is very important for stability analysis of the deep underground engineering. Using Hoek Brown failure criterion for rock consideration of the intermediate principal stress, σ2+σ3 as a independent variable and σ1-σ3 as a variable, the seven group tests data on true triaxial compression strength for Dolomite, Limestone, Trachyte, Sandstone, Shale, Marble and Amphibolite were analyzed with multi fitting approximation method. Based on the physics features of the parameters in Hoek Brown criteria （σ1-σ3=σc［m(σ2+σ3)/(2σc)+s］n）, the reasonable parameter values and computational formula were presented. The analysis results show that for high stress state at stress strength ratio κ from 1.5 to 8, the Hoek Brown failure criterion for rock consideration of the intermediate principal stress is in accordance with the seven group tests results, where parameters n, s and m can approximatively equal to 0.4, 1 and 1.5κ1.8 respectively.