Roadway layout and support in shallow contiguous coal seams under goaf

BAI Xinyuan; GAO Dengyan; CHEN Jianhua

doi:10.11799/ce202501008

Abstract：Aiming at solving the problem of long-distance roadway tunneling under goaf of shallow and contiguous seams,we take the excavation of 1-2 lower No.205 air return roadway in 1-2 coal composite area of Huojitu Coal Mine as the background,and carry out numerical calculation,theoretical analysis and engineering practice,to analyze the reasonable spacing and support parameter of contiguous seams.The research shows that:based on FLAC3D numerical simulation,the long-distance roadway layout and support structure under goaf are simulated and calculated,comparing and analyzing the roadway surrounding rock deformation and stress distribution under different coal pillar widths,seam spacing and support methods.Considering the safety factor,the roadway stagger distance is determined as 21 m.When the layer spacing is small,the support effect of anchor bolts and cables is poor,the roof is in a tensile failure state during excavation,and roof control is difficult,so a reasonable layer spacing should be greater than 3 m.Under the existing support conditions,when the thickness of top coal is 3.5 m,the displacement of the roof and floor of the roadway changes little,and no shade frame is required.The theoretical calculation shows that the maximum damage depth of the upper layer to the floor is 2.02 m,and when the thickness of top coal is 3.5 m,the support strength meets the check requirements.According to the field engineering application and the actual measurement of the surrounding rock deformation,when the thickness of top coal is 3.5 m,the joint support method of"bolt-cable-shotcrete"is adopted.The displacement of the roof and floor of the roadway changes little,and the maximum sinking of roof is 20 mm.The roof control effect is favorable,and there is no large-scale roof caving or rib spalling phenomenon in the roadway,which verifies the rationality of the roadway layout and support scheme.