Failure mechanism of three soft coal seam roadway and comparison study on bolt and grouting

According to the field investigation and experiments at No. 4606 transform cut of working face in Liangjia coal mine, which is a typical soft rock roadway, the failure mechanism of surrounding rock under primary plan was analyzed. The results demonstrated that the complex structure of coal seam, the easy expansion and softening of surrounding rock, large destruction scope, serious arch deformation, and unrealized supporting potential were the main causes of rock failure. Anchorage performance tests show that compared with the drawing force before grouting, grouting bolts increase 214% after 10 days, and high strength cables increase 89%. Took bolt-grouting support as the core measure, two supporting test schemes, namely U type shed + grouting bolt and grouting bolt + high strength cable were proposed. The results show that the surrounding rock deformations are less than 59% compared with primary plan's, differed by 6.6%. Therefore, the grouting bolt + high strength cable can be used to replace U type shed. © 2015, China Coal Society. All right reserved.