Study on the Anisotropic Mechanical Properties of Layered Surrounding Rocks in Tunnels

In order to study the macroscopic anisotropic mechanical properties of layered tunnel surrounding rock under the influence of different laminar conditions, a three-dimensional numerical model of engineering unloading of layered surrounding rock based on overlapping domain coupling was constructed according to the principle of continuous-discontinuous coupling, and it verified the continuity of the mechanical information transfer of the overlapping domain coupling model and its superiority compared with the interfacial coupling method, and the deformation characteristics and rupture distribution law of layered surrounding rock under the engineering unloading in the course of tunnel construction were investigated. The deformation of layered surrounding rock under the unloading action of the project during the tunnel construction was studied. The results show that: (1) the established continuous-discontinuous overlapping domain coupling numerical model can transfer the mechanical information better, and it is better than the interface coupling model in facing the problems of locally generated stress concentration and discontinuity; (2) for the laminar surfaces with different inclination and inclination, the damage of the boundary of the structural surface is gradually aggravated with the increase of the angle; (3) as the angle of the laminar surfaces increases, the rupture generated in the matrix of the surrounding rock is caused by the normalized rock. (3) As the angle of the laminae increases, the rupture generated in the matrix gradually changes from normal tensile dominance to tensile-shear composite dominance, and mostly gathers in the edge area of the laminae interface to spread along the structural face deeper into the surrounding rock; (4) When the spacing between strata exceeds 3 m, reducing the spacing diminishes rock mass integrity. However, when the spacing falls below 3 m, rock mass stability is paradoxically enhanced.