Abstract：For the purpose of the comparison of the influences of rock bolts¢ intervals on reinforcement effects and anti-detonating characteristics of surrounding rock around two underground openings，the different reinforcement effects of two kinds of rock bolts，which have the same length and the different intervals in surrounding rock of two underground openings，are studied by model experiments of geomechanics under the effect of explosive stress waves produced by focus charging. Because of the differences of the intervals of the rock bolts，the distinctions of stress in surrounding rock，surface strain of two underground openings，the roof-to-floor relative displacements of two underground openings，accelerations of roof，floor，sidewall and macroscopic damage forms are compared and analyzed. By comparing the caverns reinforced by the large intervals of rock bolts，the results show that the wall rock¢s stress is relative larger in surrounding rock of the underground opening reinforced by the small intervals of rock bolts. However，the surface strain of the underground opening，the relative roof-to-floor displacements and the accelerations of roof and floor of the underground opening reinforced by the small intervals of rock bolts are relative smaller；and there is no cracks in the reinforcement zone. These conditions indicate that the small interval of rock bolts should be used to reinforce the surrounding rock of underground openings. The corresponding numerical analysis of model experiment is carried out. Some parts of the model test data are compared with the results of numerical analysis. The peak values of the vault stress and the roof-to-floor displacements of model test are consistent with numerical analysis. The experimental result is reliable，and this can provide references to the design of protective projects and the reinforcement of the wall rock and tunnels.
