深埋软岩隧道大变形非线性力学特征

Nonlinear mechanical characteristics of deep tunnel in weak rock

分析隧道断面形状、初始地应力状态和岩体强度之间的关系,并利用ABAQUS有限元软件比较分析了围岩及初期支护在大变形条件下的非线性力学特性。研究结果表明:(1)围岩的非线性主要是材料非线性和接触的非线性,破坏模式表现为小应变大位移;(2)初期支护受几何非线性影响显著,力学分析应采用大变形理论;(3)初期支护应采取降低几何非线性影响的结构,改变弯曲变形模式,提高支护能力。

The relationship among the section shape,the initial in-situ stress state and the rock strength is analyzed theoretically in this paper.The analytic solution of internal force of elliptical initial support is derived,and the non-linear mechanical characteristics of surrounding rock and initial support with large deformation are compared and analyzed by ABAQUS.The findings show that:(1)The nonlinearity of surrounding rock is mainly material nonlinearity and contact nonlinearity,The failure mode is small strain and large displacement;(2)Geometric nonlinearity has a large impact on the initial support,Large deformation assumptions should be used in its mechanical analysis;(3)The initial support should adopt the structure which can reduce the influence of geometric nonlinearity,change the bending deformation mode and improve the ability of initial support.