Deformation and failure laws and control technology of gob-side roadway in close distance and thick coal seams

ZHAO Bin

doi:10.13347/j.cnki.mkaq.20250668

Abstract：Asymmetric large deformation and damage are prone to occur in the goaf during the mining process of close distance and thick coal seams,which seriously affects the safe and efficient production of the mine.Therefore,taking the 30503 working face of Tashan Coal Mine as the engineering background,a research method combining on-site measurement,theoretical analysis,and nu-merical simulation is adopted to study the deformation and damage laws of the goaf during the mining process of the working face,reveal its deformation and failure mechanism,and propose stability control technology for the goaf.The study results show that in-fluenced by adjacent goaf and filling roadway,the goaf presents significant asymmetric deformation,with a deformation of 800 mm in the middle and upper parts of the solid coal support and coal pillar support,and obvious floor heave;theoretical analysis finds that repeated mining results in the formation of a composite structure of"low-level cantilever beam+high-level masonry beam"in the overlying rock,which causes a significant increase in surrounding rock stress due to fracture and subsidence;establishing a stress transfer model for the high and low roofs,deriving the vertical stress distribution function,and verifying that the peak stress(23.1 MPa)borne by the coal pillar far exceeds its bearing capacity(11.9 MPa),the composite structure of the upper and lower roof panels and the instability of the coal pillar lead to the asymmetric deformation of the gob-side roadway;through FLAC3D numerical simulation,different reinforcement support schemes are compared for 4 types of anchor rods and 4 types of grouting depths(2-5 m),and the op-timal solution is 2 m grouting reinforcement on the side of the coal pillar(to enhance the stiffness and shear strength of the fracture surface)combined with 4 optimized anchor rods on the two sides(with an inter-row spacing of 1.2 m×2.0 m and a 15° inclined an-choring for the first/fourth rows),which achieves a 20%improvement in control effect compared to conventional support;after be-ing applied on-site,the distance between the two sides of the roadway decreased by 50%(the peak value dropped from 800 mm to 400 mm),and the distance of the roof and floor movement decreased by 40%(the peak value dropped from 520 mm to 312 mm),sig-nificantly improving the stability of the roadway.