Optimization of Roadway Support in Deep Coal Seams Based on Loose Zone Testing

Abstract

To address the problem of fractured surrounding rock and support failure in deep coal seam roadways under high-stress conditions, this study takes the auxiliary transportation roadway (west) in the 2103 panel of a mine in Shanxi Province as the research background. The ZKXG30 type mining borehole imaging device was used to conduct precise testing of the loose zone. Five observation boreholes were arranged at key cross-sections of the roadway to systematically analyze the fracture development characteristics and distribution patterns of the roof, shoulder, sidewalls, and floor corners. The results indicate that the loose zone thickness of the surrounding rock ranges from 2.36 m to 4.38 m, classifying it as a large loose zone. The shoulder area exhibits the most severe damage, showing an overall butterfly-shaped failure pattern. Based on the test results, an optimized combined support system of “ordinary cable bolts + grouting cable bolts + mesh + W steel belt + shotcrete” was designed. The sidewalls were reinforced using Φ22 mm × 5300 mm hollow grouting cable bolts. Field monitoring results show that after reinforcement, the maximum convergence of the two sidewalls is 199 mm, and the maximum roof–floor convergence is 211 mm, both within the safety limits. The stability of the surrounding rock was significantly improved.