Abstract: The weakly cemented rock mass makes poor stability. Large deformation often occurs during coal mining or roadway excavation, which brings maintenance difficulties. To address the problems of the mechanical characteristics and deformation control of the surrounding rock of the weakly cemented siltstone, we performed the field survey, laboratory tests, theoretical analysis by selecting Linchang coalmine in Guangxi Province of China as the engineering background. On-site investigations show that the roof rock layer of roadway has poor self-supporting ability, high failure rate of supporting structure due to water effect; large floor heave occurs affected by water and mining. The point load test indicates that the uniaxial compressive strength is only 1.9−2.3 MPa. Scanning with an electron microscope reveals that the weakly cemented siltstone is based on coarse-grained minerals. According to Protodyakonov’s pressure arch theory, we derived the equations of ultimate bearing capacity of roof and two sides and put forward the key points of weakly cemented roadway surrounding rock control, including improving the overall strength and bearing capacity of roadway surrounding rock, determining reasonable bolt support parameters, designing roof anchor cable to strengthen support. Based on the results of experimental analysis and theoretical research, we proposed a control plan based on grouting reinforcement, combined with bolts and cables, and carried out industrial tests in Linchang coalmine. The monitoring data show that the designed support scheme can effectively control the deformation of the weakly cemented siltstone roadway.

Key words: mining roadway, weakly cemented roof, surrounding rock stability, grouting reinforcement, combined support technology