Research On Laws Of Top-coal Movement And Strata Pressure Behavior Of Fully Mechanized Caving Face In Thick Coal Seam

Mechanized top coal caving mining method is a mining technology to achieve high production and efficiency for the thick coal seams(special thick seam) mining. This thesis takes 10-704 fully mechanized caving face of Pang Pangta mine as project example and has studied law of top coal movement and destruction on fully mechanized top coal caving face, law of overburden movement and stress distribution during working face advancing through numerical calculation, theoretical analysis and field measurement. In this thesis, results are as follows:(1) Numerical calculation results show that surrounding rock stress distribution in different locations along inclination of working face is quite different. The stress concentration degree of coal and floor is larger than roof in upper and middle parts of working face. While the stress concentration area of coal and floor increases in lower part of working face because of influence of side abutment pressure. Excavation results of the numerical model show that periodic weighting step distance of working face is basically consitent with the measured average value.(2) Comprehensive analysis results of the impact for top coal movement by stress and support show that the top coal has a greater horizontal displacement under pressure in the vertical direction, and forms dispersion zone, fissure extension zone and elastic zone within the range of influence area of abutment pressure. Support setting load is too large or too small will increase the number of roof falling on working face. Increasing top beam length of support and frequency of support movement can make top coal be fully broken and successfully released, and improve top coal recovery ratio.(3) Field measurement results show that the upper layer top coal in the same cross section which is perpendicular to the direction of working face advancing has displacement firstly. And in the same layer, the closer to the coal wall, the greater the displacement of the top coal will be. The average periodic weighting step distance of working face is 18.4 m, the average dynamic load coefficient is 1.26, and the dynamic load coefficient at both ends of working face is larger than middle part. Advancing abutment pressure effect of working face is at the range of 0~50 m, and the maximum location of advancing abutment pressure is about 13 m away from the front coal wall. The concentration factor of advancing abutment pressure is at the range of 1.80~1.99, and the lower part on working face of that is larger than upper part. While the concentration factor of side abutment pressure is at the range of 1.16~1.29, and the maximum location of side abutment pressure is at the top of isolated coal pillar and about 7 m away from the goaf edge of mined working face.