基于Hoek-Brown准则的寒区隧道围岩弹塑性分布影响因素分析

为定量确定寒区隧道开挖支护后的弹塑性应力场与塑性区半径,建立衬砌—正冻围岩—未冻围岩简化力学模型,以Hoek-Brown破坏准则为极限平衡条件,推导出寒区圆形隧洞理想弹塑性围岩的塑性区半径解析解。根据Mohr-Coulomb准则和Hoek-Brown准则的参数等效方法,对比了两种准则在不同原岩应力和围岩单轴抗压强度下塑性区分布的差异,并考虑了冻胀深度、衬砌弹性模量对冻胀力与弹塑性分布的影响。研究表明,围岩冻胀力σf与冻胀深度近似呈正线性相关,衬砌弹性模量在一定范围内对围岩冻胀力σf*有显著影响;塑性区半径Rp对围岩单轴抗压强度在一定范围内的变化十分敏感,甚至可达8～10倍洞径;高地应力条件下,基于Hoek-Brown准则与Mohr-Coulomb准则求解的塑性区半径与原岩应力p0的敏感性有差异,但均与原岩应力呈正相关。

Analysis on Influencing Factors of Elastoplastic Distribution of Surrounding Rock in Cold Area Tunnel Based on Hoek-Brown Criterion

In order to quantitatively determine the elastoplastic stress field and plastic zone radius after excavation and support of cold zone tunnels,a simplified mechanical model of lining-positive frozen surrounding rock-unfrozen surrounding rock was established.Taking the Hoek-Brown failure criterion as the limit equilibrium condition,the analytical solution of the plastic zone radius and displacement of the ideal elastoplastic surrounding rock in the cold zone circular tunnel was derived.According to the Mohr-Coulomb criterion and the parameter equivalent method of Hoek-Brown criterion,the differences between the radius and displacement of the plastic zone under different original rock stress and surrounding rock uniaxial compressive strength were compared.The influence of frost heave depth and lining elastic mode on frost heave force and elastoplastic distribution was analyzed.The research shows that the frost heave forceσfof the surrounding rock is approximately positively related to the frost heaving depth,and the elastic modulus of the lining has a significant influence on the frost heave forceσf*of the surrounding rock within a certain range;The radius of the plastic zone Rpto the surrounding rock uniaxial compressive strength is very sensitive within a certain range.The plastic zone radius Rpcan even reach 8-10 times the hole diameter.Under the high ground stress field,the plastic zone radius is solved based on the H-B criterion and the M-C criterion.It is different from the sensitivity metric of the original rock stress p0,both of which are positively correlated with the original rock stress.