岩石考虑中间主应力Hoek-Brown强度参数分析

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

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。

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 intermedi- ate 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 Am- phibolite were analyzed with multi-fitting approximation method. Based on the physics features of the pa- rameters 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 r 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 ap- proximatively equal to 0.4, 1 and 1.5r1＂~ respectively.