Experimental Study on the Bearing Behavior of Bolted and Grouted Broken Surrounding Rock of Deep Roadways in a Coal Mine

To address the inadequacy of research on the bearing behavior of bolted and grouted shallow broken surrounding rock in deep roadways. Broken coal samples with four particle size (PS) were collected, various bolted and grouted broken surrounding rock specimens were subsequently prepared with the collected coal samples by varying the water-cement ratio (WCR) and the number of bolts. The specimens were comparatively analyzed to determine their stress, strain, and crack propagation variation patterns under various parameters. The results showed the following: 1) The bearing capacity of the specimens first increased and then decreased as the PS increased. Under the same conditions, compared to the unbolted specimens, the average peak stress of the bolted specimens was 53.38% higher, whereas their average peak strain was 46.43% smaller. 2) The unbolted specimens primarily underwent tensile failure. The bolted specimens primarily underwent tensile failure, which gradually transitioned to tensile/shear-mixed failure. 3) The bearing capacity of the specimens gradually increased as j increased. However, there were inflection points for the changes in the peak stress and strain. 4) The bearing capacity of the specimens decreased as the WCR increased. However, there was no definite pattern in the morphologies of the specimens at failure.