弹塑性软化模型下隧洞围岩变形与支护压力分析

为深入探究岩体非线性软化应变特性对隧洞围岩力学行为的影响,提出了一种考虑软化系数的岩体弹塑性软化模型,并推导了圆形隧洞围岩应力-应变的求解方法。然后,通过将本文方法与Brown方法、换算后的Mohr-Coulomb屈服准则方法进行对比,验证了本文方法的合理性。最后,探究了软化系数对围岩变形及支护压力影响规律。结果表明:软化系数较大时,采用弹塑性软化模型与弹脆塑性模型算得结果基本相同;对围岩变形及稳定性起主要控制作用的是松动区域范围;控制塑性区域出现时的临界支护压力在数值上与弹塑性区域交界处径向应力是相等的。

Study of support pressure and surrounding rock deformation of a circular tunnel with an elastoplastic softening model

To provide an insight into the effect of the nonlinear strain-softening phenomenon on the mechanical behavior of the surrounding rock mass, an elastoplastic softening model considering softening coefficient is proposed. The approach for calculating the stress and strain states in the surrounding rock of a circular tunnel is presented. Then, by comparing with Brown’s method and converted Mohr-Coulomb failure criterion method, the proposed model is proved to be reasonable. Finally, effects of softening coefficient on the deformation behavior of surrounding rock and the support pressure are studied. The results show that: when the softening coefficient is relatively large, the result by the elasto-brittle-plastic model is basically identical to that by elastoplastic softening model; it is the radius of the loose region that mainly controls the deformation and stability of surrounding rock; the critical support pressure that controls the appearance of plastic region is equal to the radial stress at the elasticplastic boundary quantitatively.