Research on Model Test of Wall Rock Stress of Tunnel in Soft Rock

Wall rock stress distribution of tunnel in soft rock is researched by means of similar material model test in this paper.The result indicates that the rising interval of the wall rock stress is in the area of one time span of the tunnel and the stress concentration factor is about 1.2～1.5.As plastic zone appear resulting from the wall rock stress re-distribution,the raising interval of stress move toward the deep-part of wall rock.After lining,along with the stress around the tunnel release,the plastic zone extends continuously.Rising interval of the stress also develops toward the deep-part of the wall rock and stress concentration is weakening around the tunnel.The side wall central section,the arch foots and the vault are key parts of the tunnel where should be strengthened to support.