Influence Law of Interbedded Strata and Their Collapse on the Mining of Extremely Thick Coal Seam under Goaf

Abstract

Interbedded strata and their collapse are vital to mining pressure control for extremely thick coal seam under goaf. To ensure the stability of the support and to avoid roof collapse, some traditional underground pressure theoretical models had been widely used in the control of surrounding rock and the selection of support. However, one of the challenges for extremely thick coal seam under goaf is that the abnormal disasters, such as support crushing and water inrush that were occurring frequently. To solve this problem, the movement characteristics of overburden rocks during the mining of extremely thick coal seam under the conditions of the interlayer thickness of 5 m and 40 m were studied by using the similar simulation experiments, while the numerical simulation experiments were carried out for the interval between coal seams of 15 m and 60 m, respectively. Finally, the structure and mechanical transfer mechanism of overburden in stope under different thickness interbedded strata were analyzed dynamically, and the condition of full-thickness connection between upper goaf and lower goaf and corresponding judgment criteria are obtained. These results can guide future research on the mechanical of extremely thick coal seam under goaf, which can provide a theoretical basis and engineering reference for similar projects.

The Effect of Hydraulic Coupling on Mechanical Deformation Characteristics of Shallow Coal Seam in Western Mining Area

“…As shown in Figure 12, the initial weighting interval of the main roof of the working face is 54 m, the periodic weighting interval is 12.75~28 m, and the average periodic weighting interval is 22 m. Since the Shendong mining area is currently mainly under shallow coal seam and high-intensity mining conditions, the overburden fracture zone in this area is higher than the thickness of the bedrock, and the ground has collapsed pits, ground cracks, and step sinking damage. There is no overburden damage "three-zone" height, only overburden damage "two zones or one zone" height [44,45]. The overburden collapse of the 12401 working face only has the caving zone and the fracture zone, the height of the caving zone is 60 m, and the fracture zone is 168 m. Periodic breakage of the key stratum causes the overburden and the ground to sink; the maximum ground subsidence is 5 m. When the working face was excavated from 120 m to 160 m, the height of the overburden fracture did not increase, but the damage range and the fracture rate of the overburden fractures increased, indicating that new fractures developed and expanded laterally during this process.…”

Cutting‐Caving Ratio Optimization of Fully Mechanized Caving Mining with Large Mining Height of Extremely Thick Coal Seam

“…With a thickness of 8-20 m, a large number of extremely thick coal seams occur in northwestern China, which are mainly distributed in Shanxi, Ningxia, and Xinjiang mining areas [1,2]. Restricted by the mining height and coal wall rib spalling, the maximum mining height of fully mechanized face with great mining height (FMFGMH) is 8.8 m [3].…”