Mechanism and control strategies of floor heave in roadways under repeated mining disturbances in fully mechanized top-coal caving mining

YANG Zhen; SUN Xingguang; ZHANG Heng; YANG Kunlin; YANG Xiaoru

doi:10.11799/ce202509013

Abstract：Addressing the issue of intensified strata pressure behavior in roadways caused by repeated mining in double-roadway layout working faces,we took the return air roadway of Panel 226-upper-03 in Huangyuchuan Coal Mine as the research object.By integrating field measurements,numerical simulations and theoretical analysis,we systematically investigated the evolution characteristics of roadway stress,failure patterns of surrounding rock,and mechanism of floor heave under repeated mining conditions.Based on these findings,targeted control measures to mitigate roadway floor heave were proposed.Findings indicate that:Firstly,field measurements of surrounding rock deformation revealed that the disturbance from primary mining has a limited impact range on the roadway.The roadway remains overall stable during extraction without significant deformation or failure.In contrast,secondary mining exhibits phased strong disturbance characteristics:intense roof-to-floor deformation occurs within 40 m ahead of the working face,with the disturbance range extending up to 120 m ahead.Secondly,the evolution law of the plastic zone under repeated mining was clarified:after roadway excavation stabilizes,damage concentrates in the floor.During primary mining,the floor plastic zone expands only slightly.Secondary mining significantly aggravates the development of the floor plastic zone,with asymmetric failure patterns dominated by an inverted"7"shape.Thirdly,the mechanism of floor heave in roadways under repeated mining was revealed:the rotation angle of the principal stress dominates the expansion direction of the plastic zone,while the magnitude of the maximum principal stress determines the failure range.The weak floor further amplifies the mining-induced stress redistribution effect,ultimately triggering roadway floor heave.Fourthly,a floor heave control strategy was proposed and implemented in the field:additional 7-m-long advance supports were installed in the zone ahead of the working face,while the spacing between each unit support was reduced by 400 mm from the original design.And the field application results demonstrate that these measures effectively enhanced the coordinated deformation capacity between the floor and advance supports,improved roadway stability,and ensured safe and efficient mining operations.