基于间断位移场的隧道围岩承载能力研究

Research on bearing capacity of tunnel surrounding rock based on discontinuous displacement field

岩体是岩石块体和分割这些块体的边界的组合体。沿边界面(结构面)的局部剪切变形使得位移场产生间断,对岩体的力学性能产生巨大的影响。采用光滑函数组合来描述滑移面上的间断,得到反映岩体沿着边界局部剪切的数学模型。利用此局部剪切模型得出了应力–滑移关系具有强化阶段时圆形坑道围岩自身承载能力的解析表达式,研究了岩体滑移面对坑道围岩自身承载能力的影响。通过分析得到,自承能力在深部坑道围岩的稳定中发挥了重要作用,应力–滑移关系的强化段对围岩承载力有着很大的影响;围岩压力与坑道的埋深、坑道的尺寸以及围岩的物理力学性质等具有直接关系;围岩出现不稳定的动力现象(岩爆)与此岩体参数m关系极大,而岩体参数与接触面的软化程度、能量转移、耗散结构的几何尺寸以及弹性模量有关。

Rock mass is a combination of blocks and interfaces.Discontinuity of displacement field is caused by local shear deformation along interfaces,which has great influence on mechanical performances of rock mass.Discontinuity on slip plane is depicted with an assemblage of continuous functions,and mathematical model which is capable to consider local shear deformation along interfaces is obtained.Analytical solutions of surrounding rock bearing capacity of circle tunnel are deduced using the model when the stress-slip curve of rock has a strengthening phase.The influence of slip planes in rock on bearing capacity of surrounding rock is studied.It is concluded from analysis that the self-bearing capacity plays a great role in stabilization of deep tunnel surrounding rock,which is remarkably affected by strengthening phase of stress-slip curve.There are direct relations between surrounding rock pressure and depth or dimension of tunnel as well as physical or mechanical characteristics.The formation of unstable dynamical response is controlled by rock mass parameter m,which has relation with softening degree on interface,energy translation,geometry size of dissipation structure and elastic modulus.