Abstract：Because the existing research cannot effectively evaluate the influence degree of deformation and fracture of surrounding rock which affected by fracture distribution,with the background of soft rock tunnel project,five kinds of fracture distribution characteristics are considered which including distance from the center of the tunnel,azimuth,inclination,length and width,and basis on this,PFC~(3D)orthogonal numerical simulation is designed. The results show that:( 1) when fracture pass through the tunnel,oblique fracture would more easily lead to a major deformation or partial collapse of surrounding rock,its risk level is greater than horizontal fracture and more greater than horizontal fracture,( 2) if the rock mass near the fracture which was not pass through the tunnel was in a relatively easy rupture location,the surrounding rock would generate a new fracture channel to the surface of tunnel in the fracture location that nearest from the tunnel surface,( 3)the fracture azimuth and fracture width were the most important factor for surface convergence deformation of tunnel,besides,the fracture azimuth and fracture length played a decisive role in the fracture extension of the cross section of tunnel.

Keyword：fracture;distribution;PFC3D;orthogonal design;deformation and fracture;