| Long Wang Gou coal mine is under construction, which is located at the Xuejiawan town,Jungar Qi,Ordos,belongs to north-central of Inner Mongolia Autonomous Region.The main minable coal is the No.6 coal seam and the inclination angle ranged from 0° to 5°.Average buried depth of the coal seam is 354 m, recoverable thickness between 4m to 30.1m, an average of 22 m.The single class coal,mainly long flame coal, contains 0~32 layers of dirt band whose lithology is the same as floor with sandy mudstone and mudstone.The lithology of roof is sandy mudstone and siltstone.At first,this paper based on the background of Long Wang Gou geological conditions has the conclusion that the caving property of the top-coal in No.6 coal seam in the analysis of burial depth, coal mass strength, joint fissure, caving ratios and size and position of drawing opening. Then,we take the similar simulation experiment to draw a conclusion that mining along with caving of immediate roof during and the periodic weighting length of main roof between 14 m to 37 m.With the face advancing, The formation and break of cantilever beam,the formation and instability of voussoir beam and structure alternating which result in the periodic weighting have occurred at overlying strata.At the same time, lead abutment pressure has increased and the peak reaches 9.2Mpa~11.7Mpa.Numerical simulation and theoretical calculation show that shearing and tensioning are the main failure modes of roof in the face and working resistance of support should not be less than 14633 kN.The roof above coal wall has the performance of composite failure,but the roof above goaf is mainly with tensioning.The result shows that it will be safe to select 5.0m×2.05 m of the support that has the characteristics 15000 k N of rated working resistance(two-leg shield), 1.46 MPa of support strength, 12000 kN of rated setting load, 1.23 of average increasing load modulus in the No.6 coal seam of Long Wang Gou coal mine. |
PDF Full Text Request