Distribution Characteristics and Formation Mechanism of Surface Crack Induced by Extrathick Near Horizontal Seam Mining: An Example from the Datong Coal Field, China

Abstract

Under the mining condition of extrathick coal seam, the overburden moves violently, the surface is destroyed seriously, and the discontinuous deformation such as cracks is fully developed. Taking Datong mining area as an example, this paper studies and analyzes the development characteristics and generation mechanism of surface cracks in loose layer covered area and bedrock exposed area by means of field measurement and similar model experiment. In the bedrock exposed area, there is no main crack. The width, length, number, and step drop of surface cracks are relatively small. There are many cracks with the same scale and distributed evenly and parallel. However, in the loose covered area, the main cracks are mainly located above the open-off cut and the stoppage line side that is deviated from the working face. There are many secondary cracks around the main crack, with a large crack density and a few cracks in the outer edge of the main crack. Through research, it is found that three mining faces belong to the typical three-zone mining mode and the main fracture is consistent with the O-ring fracture distribution theory. This research’s results can provide theoretical and technical support for the follow-up land remediation and ecological restoration.

Study on Evaluation and Prediction of the Degree of Surface Damage Caused by Coal Mining

“…At present, the proportion of coal consumption to total primary energy consumption began to decline after implementation of the coal industry rationalization action by the Chinese government (Wang et al, 2020;Yan et al, 2018;Xie et al, 2021). But coal still plays an important role in the development of regional economy, especially the western China economy (Yan et al, 2021;Zhu et al, 2018). Undoubtedly, exploitation of coal resources will do harm to the environment of the ground surface, such as exhaustion of groundwater resources, death of vegetation, cracking of the land, and damage to surface structures, such as railroad tracks, roads, and buildings.…”