Experimental study of influence of joint space and joint angle on rock fragmentation by TBM disc cutter

To study the rock joint parameters, joint space and joint angle of rock fragmentation by full face rock tunnel boring machine (TBM) disc cutter, the test of high-strength gypsum specimen penetrated by wedge indentation is applied. Data of penetration depth and loads during the loading process are collected. Shooting with the camera in real time, photograph of the specimen surface damage and failure mode of the development process are taken. The results show that: when joint angle is constant, a greater joint space needs a greater penetration load when loading value drops, it also needs greater penetration power and crack propagation energy; when joint angle equals to 0 and 90, anti-invasive factor is consistent. When the joint angle equals to 30 and 60, with the increase of joint space, anti-invasive factor increases. When the joint spacing is constant, with the increase of the angle, the peak load, penetration power and crack propagation energy decrease and then increase. When joint angle equals to 30, the values are the minimum. According to a morphological analysis after the destruction of specimens, it is found that the spatial characteristics of joints crack obviously control the crack mode and have significant limitations for the damage region