# Stability and Force Chain Characteristics of \"Inclined Step Cutting Body\" in Stope
###### Abstract
It is considered that the main factors affecting the surface discontinuous deformation are mining depth, mining method and fault. [PERSON] et al. [12] and [PERSON] et al. [13] conducted case studies on the landslide caused by coal mining in northern Natta, Australia. The discontinuous numerical simulation method was used to analyze the ground motion mechanism of landslide formation, and the effects of geological factors, such as rock mass characteristics, bedding and joints on mining landslides were discussed. Based on the field practice, the above studies investigated the characteristics of overlying strata and surface movement and deformation under a shallow coal seam by different means, and explained the weighting phenomenon of the working face. A large number of studies show that particle matter theory has become a way to solve practical engineering problems [14; 15; 16; 17; 18]. [PERSON] [14] introduced the physical mechanism of particulate matter in engineering problems and analyzed the mechanical properties of particulate matter. [PERSON] et al. [15] weakened the strength characterization of joint elements according to the particle matter theory, and the authors used PFC3D Numerical simulation software to simulate the joint direct shear test of rock specimens. [PERSON] et al. [16] explored the force chain characteristics inside the particles under the shear state of the parallel plate by simulation. The results show that the force chain shape changes with the shear speed, and the contact force size also shows different distribution laws at different times and particle flow states. [PERSON], [PERSON] et al. [17] carried out the relevant research on the evolution law of force chains and fitted the curve equation of the force chain arch. [PERSON] et al. [18] examined the effect of barrier locations, in particular the source-to-barrier distance, on the velocity and volume of debris flows via the numerical approach, based on smoothed particle hydrodynamics (SPH). The above research results provide some new ideas for rock stratum simulation. The overlying strata movement and the evolution process of ground fissures are a discrete medium problem of discontinuous large deformation. A large number of scholars use a series of numerical simulation methods to solve large deformation problems, such as MPM and FEM [18; 19; 20; 21; 22; 23; 24]. However, these methods cannot directly describe the caving characteristics of overlying strata in slopes, and rarely consider the mechanical relationship between the internal particles of strata under a shallow thick coal seam. In view of this, taking the 22,021 working face of a coal mine in the west as the research background, this paper combines both the theoretical analysis and PFC numerical simulation to describe the rock strata collapse morphology in the mining stage of a shallow thick coal seam. The structure of the \"inclined step cutting body\" under shallow buried thick coal seam is proposed, and its correctness is verified by numerical simulation. The evolution process of force chains under a shallow thick coal seam is revealed for the first time, and the trajectory equation before the instability of the force chain arch is corrected, and the root causes of serious subsidence damage on the surface are explored.