High Strength Bolt Support Technology and Application to Mine Large Cross Section Seam Gateway

Based on the analysis on the problems existed in the bolt support of the present large cross section seam gateway, a new knowledge of the bolt support mechanism was stated and a high strength bolt suitable for the mine large cross section seam gateway was developed.The FLAC3D finite differential program was appli ed to the simulation analysis on the stress field distribution features and law of the surrounding rock along the seam gateway with different bolt support parameters.The results showed that the pre-tensile strength was the decisive parameter of the bolt support system and the increased pre-tensile strength of the bolt could effectively im prove the stress value and expansion scope of the stress field in the surrounding rock of the mine gateway.The selection of the bolt length should fully consider the pre- stress of the bolt, the broken degree and boltability of the gateway surrounding rock.As for the same material of the bolt, the larger diameter of the bolt, the higher stren gth of the bolt would be and the larger of the pre-stress expansion scope would be.When the bolt was vertical to the rock stratum surface, the distribution of the pressur e stress zone formed by the gateway surrounding rock would be more even and the superposition effect of the bolt pre-stress would be better. The underground mine tes ts showed that the high strength bolt support technology could provide the effective support means to the large cross section seam gateway.During the gateway driving period, the convergence between the two side walls was 25.0 mm, the convergence between the roof and floor was 16.6 mm and the serious deformation of the surroun ding rock could be effectively controlled.