Experimental Study of Effects of Joint on Rock Fragmentation Mechanism by TBM Cutters

To study the effect of rock joint parameters, the joint orientation, the filling situation of joint and the distance between the center of joint and the position of penetration on rock fragmentation mechanism by tunnel boring machines (TBM) cutters, a series of penetration tests were conducted on rock-like specimens using the modified triaxial testing machine. Data of indentation load and penetration depth during the loading process were recorded and analyzed. Results show that the filling situation of joint can significantly influence the resistance of rock to penetration. The joint interface closer to the position of penetration plays a more positive role in rock fragmentation than that farther to the position of penetration. The joint orientation can greatly affect the peak indentation load, the anti-invasive factor, the crushing work as well as modes of rock fragmentation. With the increase of joint orientation, the peak indentation load, anti-invasive factor and crushing work decrease firstly, and then increase. When joint orientation equals to 60° and 90°, they reach the minimum and maximum values, respectively.