The effect of joint roughness coefficient (JRC) and joint compressive strength (JCS) on the displacement of tunnel

ABSTRACT: Shear strength of rock mass, joint surfaces and discontinuities and joint dips have important role in the analysis of the stability of underground constructions which designed and implemented in rock. So understanding the factors affecting the shear strength of discontinuity that separates the blocks makes it seem necessary. One way to estimate the shear strength of the joints and joint behaviour in rocks is using empirical theory of Barton. Joint roughness coefficient (JRC) and joint compressive strength (JCS) are the parameters of this equation. This study used data from Tizhtizhgaran tunnel that have been dug in the shale rocks. In this tunnel modeling, seven dips of joints in 0 , 15 , 30 , 45 , 60 , 75 , 90 angles analyzed using Phase2 software and displacement diagrams are plotted on the sections of tunnel under static load. In addition, the effect of increasing joint compressive strength is evaluated on the joint roughness in around of tunnel. The obtain results show that the joint dip, joint compressive strength and joint roughness coefficient have different influences on the displacement of tunnel. With increasing joint roughness coefficient from 0 to 15, displacement in around of tunnel is decreased and from 15 to 20, the displacement is increased. With increasing the dip of joints from 0 to 90, the values of JCS and JRC have greater effect in the displacement in around of tunnel.