摘要
The breaking features and stress distribution of overlying strata in a steeply dipping coal seam(SDCS)differ significantly from those in a near-horizontal one.In this study,the laws governing the evolution of vertical stress release and shear stress concentration in the overlying strata of coal seams with different dip angles are derived via numerical simulation,rock mechanics tests,acoustic emissions,and field measurements.Thus,the stress-driven dynamic evolution of the overlying strata structure,in which a shear stress arch forms,is determined.Upon breaking the lower pari of the overlying strata,the shear stress transfers rapidly to the upper part of the working face.The damaged zone of the overlying strata migrates upward along the dip direction of the working face.The gangue in the lower part of the working face is compacted,leading to an increase in vertical stress.As the dip angle of the coal seam increases,the overlying strata fail suddenly under the action of shear stresses.Finally,the behavioral response of the overlying strata driven by shear stresses in the longwall working face of an SDCS is identified and analyzed in detail.The present research findings reveal the laws governing the behavior of mine pressure in the working face of an SDCS,which in turn can be used to establish the respective on-site guidance.
基金
the National Natural Science Foundation of China(Grant No.51634007)
the Graduate Innovation Fund Project of Anhui University of Science and Technology of China(Grant No.2019CX1003).
