Analysis and Monitoring Technology of Upper Seam Mining in Multiunderlayer Goaf

Based on the background of close coal seam mining in Qianjiaying mine, Tangshan, China, feasibility upper complex underlaying goaf is analysed using roof caving analysis and numerical method. The deformation roadways monitored by field measurement 3D laser scanning. characteristics #5 after 1378P, 2071P, 2072P, 2091P working panels with a depth 39–54 m below are Results show that maximum superimposed area lower goafs reaches 2.5 single 1.5 m. inclination 1.9°. subsidence floor 1359P obtained measurement, result consistent calculation. ZEB-HORIZON scanner was used to measure model roadway deformation. multiple scanning data, obtained. surrounding rock not great, displacement fall 30 mm, rib convergence 25 mm. It can be concluded recovered this underlying seams’ condition.