Experimental Study on Shear Behavior of Bolted Cement Mortar Blocks under Constant Normal Stiffness

In this paper, the influence of bolting on shear mechanical behavior of cement mortar specimens were studied. First, a shear test apparatus which could provide CNS (constant normal stiffness) condition was designed. Then, more than 140 bolted and non-bolted cement mortar blocks (100 x 100 x 100 mm) were prepared. The strengthening effect of bolts with diameters of 0 - 10 mm on cement mortar specimens was studied under different initial normal loads ranging from 20 kN to 60 kN and constant normal stiffness of 420 kN/mm. Two simplified models of shear behavior of reinforced cement mortar blocks were proposed. The most important influence of bolt on the cement mortar blocks was to strengthen the post-peak shear strength rather than the peak shear strength, and the strengthening effect was reduced under high initial normal force. The cohesion of cement mortar blocks was reduced while internal friction angle was increased in residual sliding stage by bolts. The dilation of reinforced cement mortar specimens in post-peak shear stage was significantly reduced due to bolting, and the larger the bolt diameter, the greater the reduction in the block dilation.