基于结构面几何参数的深部隧洞围岩破坏机理研究

Failure Mechanism of Surrounding Rock of Deep Tunnel in Consideration of Varying Geometric Parameters of Structural Planes

岩体的强度主要由结构面控制,为确定结构面对隧洞围岩的影响,在对围岩中单一结构面的应力分布和破坏形式进行理论分析的基础上,研究了结构面倾角以及结构面到隧洞中心的距离对节理围岩破坏机理的影响。并利用3DEC离散元程序分别对不同结构面分布、不同岩石强度和结构面强度下18种组合的围岩变形进行了计算,分析了结构面不同分布情况下围岩的破坏模式;对比分析岩石、结构面强度不同组合下岩石强度和变形特征,研究了结构面力学变形性质在岩体损伤破坏中的贡献。研究结果表明:结构面距开挖轮廓线越近越容易发生破坏;结构面倾角影响结构面首先发生破坏的位置;结构面的分布决定围岩首先发生破坏的位置,结构面的破坏不一定会导致围岩的破坏。研究成果对不同结构面组合分布的围岩变形和破坏分析具有一定的指导意义。

The strength of rock mass is controlled by structural plane. On the basis of theoretical analysis on stress distribution and failure mechanism of single structural plane in surrounding rock,the influences of dip angle of structural plane and distance from structural plane to tunnel center on the failure mechanism of jointed rock mass are researched. The results are concluded as follows: 1) discontinuities are more likely to occur when structural plane is closer to the excavation contour line; 2) the position where structural plane first destructs is affected by the angle of structural plane. Furthermore,the deformation of 18 groups of rock masses with different combinations of discontinuity distribution,rock strength and discontinuity strength are calculated and compared in three-dimensional element code( 3 DEC),and the failure mechanisms of surrounding rock with various discontinuities distribution are analyzed. The contribution of structural plane 's mechanical properties to rock failure is also studied: the distribution of structural plane determines the location of the first failure; and the failure of structural plane does not necessarily lead to the failure of surrounding rock.