Abstract: In the present study, the closure behavior and shear strength of mudstone fracture are investigated through direct shear test before and after grouting. Experimental results have shown that 1) The closure deformation of the mudstone fracture decreases by about 49%-57% after grouting; 2) The peak shear strength and residual shear strength can be easily observed; and 3) The shear stiffness of the mudstone fracture increases after grouting. The preliminary reasons for the phenomenon are general due to the increasing contact area caused by the filled material, which can transfer the loading and thus increase the shear strength.

Key words: mudstone fracture, grouting reinforcement, normal deformation, shear strength