| Because of the original design scheme of Fengjiata Coal Mine of shallow buried and close coal seam group,the roadway is arranged vertically,resulting in the influence of the continuous disturbance of the upper coal seam and the superposition of the stress of the coal pillar in the two layers of the lower coal seam in the 2 and 4 coal seams which are close to each other.The lower coal seam roadway is damaged to a certain extent,resulting in the decrease of surrounding rock strength and easy rupture,and a higher strength support is needed.in order to avoid the damage of the roadway caused by the superposition of section coal pillar stress,the staggered arrangement of upper and lower coal seam roadway is adopted.At this time,the self-stability of the roadway is enhanced,so that the support strength is obviously improved,and the possibility of excessive support exists in the original support mode.In this paper,the 1204 and 1405 working faces in Fengjiata Coal Mine are taken as the research object after the staggered arrangement of the roadway in the upper and lower coal seams.By means of theoretical calculation,numerical simulation and field measurement,the roadway layout and support system design under the condition of close coal seam mining are studied systematically.after mining 2 # coal seam,The movement and deformation law of strata between goaf and No.4 coal seam on the surface and No.2 coal seam,and the optimization parameters of coal roadway support in each layer are calculated.The specific research contents are as follows:(1)The mechanical properties of the roof and floor of each coal seam and the coal are analyzed and classified by means of the mechanical properties test of the surrounding rock;(2)Through the detection results of borehole peephole,combined with the actual situation of No.2 coal seam mining roadway,it is determined that the surrounding rock classification of roadway in No.2 and No.4 coal seam face of Fengjiata Coal Mine is IIIgeneral surrounding rock,which should be designed by bolt suspension theory.The corresponding support mode is "bolt + anchor mesh" support;(3)The optimized supporting parameters: extraction tunnel roof adopts ?18 × 1800 mm l type without longitudinal reinforcement rebar anchor,row spacing between 2 # and 4 #seam,respectively 1100 × 1100 mm and 1200 × 1200 mm.The two sides are of type 16 × 1700 mm,and the row spacing is 1200 × 1200 mm.(4)Through the analysis of the numerical simulation results,the optimized plastic zone range of roadway support in 1402 working face becomes smaller,the roof subsidence is also greatly reduced,and the stress of roadway surrounding rock is weakened,which indicates that the optimal design of support scheme plays a good supporting effect;(5)According to the reasonable working resistance of the working face,the reasonable working resistance is 1786.06 kN ~ 8336.47 kN,which does not exceed the rated working resistance 8500 kN.The results show that the ZY8500/17/ 35 D hydraulic support can meet the requirements of the working face of the roof.According to the mechanical properties of surrounding rock,the test results of loosening ring,combined with the law of mine pressure appearance and numerical simulation experiment,the stability of the support scheme is verified,and the safe,reliable,economical and reasonable roadway support parameters are finally determined.The problem of roadway support in Fengjiata 1406 working face is solved,which provides an accurate support scheme for mining area and provides a basis for similar mine support design. |
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