Mechanism and control technology of support instability in fully-mechanizedmining face in thick coal seam with large dip angle and fault

The stability control of the support is one of the key issues for the safe and efficient mining of the longwall working face in the large-inclined coal seam. Taking the No.11513 large-inclined thick seam fully-mechanized coal mining face in Pansidong Mine as the background, based on the monitoring and analysis of the on-site overlying strata breaking and moving laws and the support loading characteristics, theoretical analysis methods were used to establish a mechanical model of the support inclination in a large inclined working face, to study the mechanical behavior response of the support under the roof load, and to define the support′s anti-collapse stability performance coefficient and anti-sliding stability coefficient, the critical inclination angle of support toppling and sliding was deduced, and the influence of coal seam inclination angle and equipment parameters on support stability was discussed. The results show that: in the mining of thick seams with large inclination, affected by the increase of mining height, the amplitude of roof fracture and movement and the working resistance of supports are significantly larger than those of general large-incline coal seams, and and the phenomenon of squeezing and biting is obvious. Due to the influence of migration, the support moves with the movement of the top plate, increasing the friction and initial support force between the support and the top and bottom plates,which can effectively prevent the support from slip ping; under the coupling effect of multiple factors, the stability coefficient of the support against collapse varies with the width of the base increase, and decreases with the height of the center of gravity and the weight of the support; from the subjective and objective aspects, the reason for the support deflection in the 11513 working face is systematically analyzed, and it is obtained that the large coal seam inclination, complex fault structure, and incomplete anti-skid measures are the major factors of the instability of the support. Proposed measures such as grouting to reinforce the broken roof, laying double-layer metal mesh, accelerating advancing speed, and installing anti-skid devices; during mining, the roof of the working area 3 coal missing area and abnormal area shall be strictly controlled and the support shall be adjusted in time to improve the stability of the working face support system to ensure safe and efficient mining.