Floor heave characteristics and control technology of the roadway driven in deep inclined-strata

Based on in-mine instrumentation and theoretical analysis of the unsymmetrical large-deformation that occurred in the roadway after excavation, Differential Floor Heave (DFH) was found to be the main reason for roadway failure. It needs to be pointed out that the specific roadway was driven in inclined rock strata. In addition, the factors that contribute to the occurrence of DFH are discussed in detail. It is believed that DFH is triggered by the unsymmetrical stress distribution in the floor and the different rock types encountered near the two floor corners. Hence, DFH control should be focused on the left floor corner where shearing failure occurs initially and the left floor surface where tensile failure is more severe. The proposed DFH control strategies include unsymmetrical grouting for the whole roadway, re-design of the roof and ribs support, reinforcement of the weak zones, and release of the concentrated stress in the earlier stage. Meanwhile, it is recommended that in the later stage, both bolts and cable bolts with higher strength and the backfilling technique using the coal measure rocks and concrete should be employed in the reversed-arch floor. The field instrumentation results, after using the proposed control strategies, indicate that large deformation in a DFH roadway has been successfully controlled.