Reasonable Working-Face Size Based on Full Mining of Overburden Failure

Abstract

To improve production efficiency and prevent potential disasters in coal mines, comprehensive research methods such as similar simulation, numerical simulation, theoretical analysis, and on-site detection were used in this study. The migration characteristics of overburden rock under different working face lengths and development heights of water-conducting fracture zones were investigated via these methods in order to determine the reasonable length of the working face. The results show that the regularity of the development height of water-conducting fracture zones in similar simulations and numerical simulations is highly consistent, and the final stable values are 48 and 50 m. When the working face length was 300 m, the error between the simulated value and the value calculated from the formula dropped below 10% and exhibited a further decreasing trend; as a result, the working face length of 300 m was found to be the turning point for the development height of the water-conducting fracture zone to become stable. Based on the simulation results and mining damage theory, the critical size of the working face was 307.6 m, and the height of the water-conducting fracture zone was determined to be in the range of 45.5–60.5 m. The actual detection result of the height of the water-conducting fracture zone under the critical size of the working face was 55 m, which conforms to the law obtained from the simulation. Finally, the reasonable working face length under the geological conditions of a coal mine was determined to be 300–400 m. This study offers important reference value for determining the reasonable working face length under similar geological conditions, and may have significance for the sustainable development of coal resource mining.