Dip angle effect of stress transfer path in floor of longwall stope in steeply pitching coal seam

ZHU Kaipeng

doi:10.11799/ce202505015

Abstract：In order to explore the dip angle effect of mining-induced stress transfer path in longwall stope floor of steeply pitching coal seam,we took the steeply pitching longwall fully mechanized mining face of Xinjiang 2130 Coal Mine as the engineering background,and combined the methods of combining physical similarity simulation with numerical calculation.After comprehensively determining and analyzing the general law of asymmetric deformation and failure of floor,the transmission path of floor mining stress and its dip angle effect were studied,and the evolution characteristics of principal stress gradient and direction deflection of floor in steeply pitching stope were quantitatively characterized.The results show that,during the mining,due to the influence of coal seam dip angle,the stress transfer path of floor mining is asymmetric inverted arch.In the stress arch,the immediate floor and the main floor of the middle and lower part of the working face are in a tensile state.Outside the stress arch,the principal stress in the floor deviates toward both sides of the coal body,with the stress deflection boundary serving as the demarcation line.Moreover,with the increase of coal seam dip angle,the arch height of floor stress arch and the stress concentration coefficient of the coal floor below the dip of working face evolves in the trend of decrease-increase-decrease.The magnitude of the first principal stress and the unloading coefficient gradually decrease,with the maximum unloading position migrating toward the coal body on the lower side of the working face.The first principal stress deflects to the positive direction of the x-axis,leading to a gradual decrease of the floor failure depth.As a result,the maximum failure depth of the floor is located in the middle-lower region of the working face.Meanwhile,under the unbalanced constraint of gangue in goaf,the floor block structure in the middle-upper region of the working face is more prone to instability and sliding,with upward expansion likely under continued mining disturbance.Based on this,the stress environment and structural characteristics of the floor in the area can be improved by taking"key attention and regional control"prevention and control measures in the area where the floor is easy to be damaged and slipped,so as to control the floor stability of the long-wall stope in steeply pitching coal seam.