Dip angle effect on asymmetric load transmission path of overlying rock in inclined mining area

Objectives The dip angle of coal seam is the root cause that the load transfer path of overlying strata in inclined stope is much more complicated than that of general coal seam. It is of great significance to clarify the load transfer path of overlying strata in inclined stope and its dip angle effect to realize the stability control of surrounding rock of this kind of coal seam. Methods Based on the engineering background of a mine in Xinjiang, the asymmetric deformation and failure characteristics of overlying strata in inclined stope are analyzed by means of physical similarity simulation, finite element numerical simulation and theoretical calculation, and the roof stress characteristic quantity is constructed to study the load transfer path and inclination effect of overlying strata under different dimensional conditions. Results and Conclusion The results show that: (1) In the process of inclined coal seam mining, the transfer path of roof stress characteristic quantity is the distribution of tendency 'm' shape and strike double 'n' shape. In the direction of parallel coal seam, the transfer path of roof stress characteristic quantity is double 'v' shape distribution, so that the overburden load within the mining influence range and outside the stress boundary is transmitted to the coal wall around the stope in two directions, while the overburden load within the stress boundary is transmitted to the coal body on both sides of the working face. (2) With the increase of the dip angle of the coal seam, the deflection boundary range of the stress characteristic quantity of the stope roof gradually decreases, so that the peak value of the abutment pressure around the stope gradually decreases. (3) Affected by this, the fracture shape of the roof of the inclined stope is asymmetrically distributed in the middle and upper part, which is larger than that in the lower part. As a result, the working resistance and its dispersion degree of the support in the middle and upper part of the working face are large, and the partial load and no-load phenomenon of the support are frequent, while the working resistance and its dispersion degree of the support in the lower part of the working face are relatively small. (4) The asymmetry of the load transfer path of overlying strata is the root cause of the regional distribution of the mechanical behavior of the roof in the inclined stope, and this phenomenon becomes more and more prominent with the increase of the dip angle of the coal seam.