【摘要】 通过数值模拟研究了锚杆支护对峰后围岩的支护效应。首先,基于Mohr-Coulomb峰后应变软化的遍布节理模型,建立了临界塑性剪切应变η*与支护阻力的耦合关系;然后,根据锚杆加固机理,将锚固作用后围岩的力学参数嵌入到应变软化模型中;最后,将临界塑性软化系数η*影响下的应变软化模型嵌入有限差分FLAC3D中,并通过对锚杆支护下的围岩震荡应力场等分析,研究了不同锚杆支护长度对深部洞室围岩分层破裂范围及应力、变形的影响。数值研究分析表明:考虑锚杆支护,围岩分层破裂化现象明显减弱;支护条件下的围岩应力场、位移及破裂区范围与未支护时差异明显。在一定范围内增加锚杆长度,可使围岩应力峰值点向洞壁移动,破裂区半径减少,拱顶和拱脚沉降均减少;当其支护长度超过临界长度后,竖直和水平方向破裂区半径以及沉降量均趋于稳定值,且两方向上破裂区半径及沉降的数值接近。更多还原

【Abstract】 Bolting supporting effect of the post-peak surrounding rock was studied through numerical simulation. Based on the Mohr-Coulomb post-peak strain-softening joint model,the coupling relationship between the critical plastic shear strain η*and support resistance was established. According to the bolt reinforcement mechanism, the parameters affected by the mechanical anchoring were embedded in the surrounding rock strain softening model. The strain-softening model under the influence of critical plastic softening coefficient η*was embedded into the finite difference software FLAC3 D. Through the surrounding rock stress field concussion bolting analyzed under the studied range of stress,the tunnel surrounding rock’s stress,deformation and broken rock species distribution of different length bolt support were discussed. The numerical analysis shows that considering the effect of bolt support,zonal disintegration of the surrounding rock obviously weaken; the surrounding rock stress field,displacement and broken zone under the condition of support are clearly different compared to those not being supported. Increasing the anchor length within a certain scope can make the surrounding rock stress peaks move towards the cave walls,the rupture zone radius decrease,and the settlement of vault and arch foot decrease. When the supporting length exceeds the critical length,the vertical and horizontal fracture zone radius and settlement tend to be a stable value,and the zone radius of two directions on the rupture and the subsidence numerical value are close to each other.更多还原