Resist-decreasing effects of rock bolts on strength of rock mass around roadway—insight from numerical modeling

To investigate the resist-decreasing effects of rock bolts on the strength of the rock mass around a roadway, a comparative study has been carried out using the numerical analysis code FLAC3D. An unsupported and a rock bolt supported model have been built for comparison. Two types of rock mass strength, the uniaxial compressive strength (UCS) and the triaxial compressive strength (TCS) of rock mass have been obtained from each model, using a prepared Fish based on the Mohr-Coulomb criterion. The results indicate that when a roadway is excavated, both the UCS and TCS in a definite local rock mass around the roadway would inevitably decrease, no matter whether the roadway is supported or not. The major decreasing region did not settle in the middle of the roadway surface, but within a deeper horizon into the rock mass. The resist-decreasing effects of rock bolts both on the UCS and the TCS of rock mass around roadway are significant.