结构面分布特征对隧道围岩变形影响的数值模拟分析

结构面对隧道围岩变形及稳定性起着决定性作用。运用三维离散元方法(3DEC)研究结构面分布特征,重点是结构面线密度1/λ、强度和倾角对隧道围岩变形的影响,总结了结构面分布与围岩变形特征的关系。结果表明,在结构面强度较低的情况下,结构面线密度对隧道变形的影响较大,其影响可分为两种情况:①λ≤0.2时,围岩的弯曲变形大于沿结构面的剪切变形,属于应力型大变形;②0.2<λ≤0.4时,沿结构面的剪切变形大于围岩的弯曲变形,属于结构型大变形。结构面倾角主要影响围岩大变形发生的位置。将数值模拟结果与国内工程实例实测变形资料相对比,发现一致性较好。本研究结果对隧道支护结构的设计以及施工设计具有借鉴意义与指导作用。

Numerical Simulation of Influence of Structural Plane Distribution Characteristic on Deformation of Tunnel’s Surrounding Rock

Structural planes largely influence the deformation and stability of surrounding rocks of tunnel.In this paper,the surrounding rock deformation of tunnel due to structural planes distribution characteristics such as structural planes′linear density,dip angle and strength was studied using 3DEC.Surrounding rock deformation characteristics related to different structural planes distribution were summarized and the mechanism of the deformation was analyzed.The results show that if the strength of the structural plane is lower the influence of structural plane′s linear density will has an evident influence on deformation of the tunnel and the influence can be divided into two cases:(1) in the case of λ≤0.2,shear deformation on structural plane is less than bending deformation of surrounding rock and the squeezing deformation is stress induced;(2) in the case of 0.2<λ≤0.4,shear deformation on structural plane is more than bending deformation of surrounding rock and the squeezing deformation is structure induced.Dip angle of structural plane mainly changes the location of squeezing deformation.Simulation results and measured data of projects at home have good consistence by comparison.These results give a reference to design and construction of supporting system of tunnels.