基于收敛——约束法的剪胀——软化型隧道围岩——支护结构相互作用

Surrounding Rock-supporting Structure Interaction of Dilatancy-softening Tunnel Based on Convergence-constraint Method

目前的隧道围岩支护结构计算方法未能很好地同时考虑围岩剪胀及软化特性和中间主应力的共同影响。首先介绍了考虑岩石剪胀及软化效应的隧道围岩力学模型及考虑中间主应力的广义SMP强度准则。而后,根据收敛—约束法中隧道纵向变形曲线、围岩特征曲线、支护特征曲线的相互关系,建立了能够同时考虑隧道围岩剪胀及软化特性和中间主应力影响的隧道围岩—支护结构相互作用力学模型,并验证了其合理性。最后,采用敏感性分析分别探讨了地应力参数、支护结构参数和岩石参数对围岩最终位移、支护结构最终支护力及变形量的影响。结果表明:地应力的增加将导致围岩变形及塑性区增大,所需支护力增加。中间主应力系数对计算结果有较大影响,应予以考虑;支护结构弹性模量的增加可以提高支护力,并大幅度减少围岩和支护结构变形;岩石弹性模量及临界软化系数的增加可以降低围岩变形及支护结构受力。

The current calculation method of tunnel surrounding rock supporting structure fails to consider the combined effects of surrounding rock dilatancy and softening characteristics and intermediate principal stress.Firstly,the mechanical model of tunnel surrounding rock considering rock dilatancy and softening effect and the generalized SMP strength criterion considering intermediate principal stress are introduced.Then,according to the relationship between the longitudinal deformation curve of the tunnel,the characteristic curve of the surrounding rock and the support characteristic curve in the convergence-constraint method,a mechanical model of the interaction between the surrounding rock and the supporting structure of the tunnel is established,which can consider the dilatancy and softening characteristics of the surrounding rock of the tunnel and the influence of the intermediate principal stress,and its rationality is verified.Finally,the sensitivity analysis is used to discuss the influence of in-situ stress parameters,supporting structure parameters and rock parameters on the final displacement of surrounding rock,the final supporting force and deformation of supporting structure.The results show that the increase of ground stress will lead to the deformation of surrounding rock and the increase of plastic zone,and the required supporting force will increase.The intermediate principal stress coefficient has a great influence on the calculation results and should be considered.The increase of elastic modulus of supporting structure can improve the supporting force and greatly reduce the deformation of surrounding rock and supporting structure.The increase of rock elastic modulus and critical softening coefficient can reduce the deformation of surrounding rock and the stress of supporting structure.