高地应力层状软岩隧道非对称挤压大变形分级修正方法研究

An improved classification method of asymmetrical squeezing large deformation of layered soft rock tunnels under high geo-stresses

为探明高地应力层状软岩隧道非对称大变形特征,收集200个高地应力层状软岩隧道大变形案例数据,统计分析非对称大变形的影响因素,采用关联规则方法分析隧道相对变形量、非对称变形部位,研究非对称大变形分级修正方法。结果表明:高地应力层状软岩隧道大变形分级非对称主要因素为岩层倾角α、岩层走向与隧道轴线夹角β、原岩应力场最大主应力与岩层面夹角γ。得到大变形分级基本因素(围岩抗压强度、最大主应力值)与相对变形量、大变形分级非对称主要因素(α,β,γ)与非对称变形部位之间的20条强关联规则,揭示了α,β,γ与非对称变形的规律:随α增大,非对称变形部位从边墙和隧底转移到边墙和拱顶;随β增大,非对称变形部位从拱顶和边墙转移到隧底和边墙;随γ增大,非对称变形部位从隧底转移到边墙再到拱顶,非对称变形部位由α,β,γ共同决定。以强度应力比和相对变形量判定大变形基本等级,以大变形分级非对称主要因素α,β,γ判识大变形部位,建立非对称挤压大变形分级修正方法,取得了良好的应用效果。研究成果为层状软岩隧道非对称大变形分级判识提供了一种重要方法。

In order to explore the classification method of asymmetrical large deformation of high stress layered soft rock tunnels,deformation data of 200 tunnels in soft rock are collected,and the major factors of asymmetrical deformation are analyzed. Relative deformation and asymmetrical deformation positions of the tunnels under high geo-stresses are investigated based on the association rule,and an improved classification method of asymmetrical squeezing deformation is put forward. The results show that the asymmetry factors are the inclination angle of the strata(α),the angle between the rock strike and the tunnel axis(β),and the angle between the maximum principal stress of the initial stress field and the rock plane(γ). 20 strong association rules,about the basic factor(compression stress and maximum principal stress) along with the relative deformation, and asymmetrical factor(α, β,γ)corresponding to asymmetrical deformation position,are obtained. It is revealed that α,β and γ together control the asymmetrical deformation position,which shifts from the sidewall and the bottom to the vault with increasing α,from the arch and the sidewall to the bottom with increasing β,and from the bottom to the sidewall and then to the vault with increasing γ. The strength-stress ratio and the relative deformation determine the basic level of the squeezing,and the asymmetry factors α,β,γ as sub-indexes identify the squeezing deformation position. The proposed method according to the level of the squeezing and the asymmetry factors provides an important approach for the asymmetrical large deformation classification of layered soft rock tunnels.