Characteristics of overlying strata and mechanisms of arch beam failure in shallowly buried thick bedrock coal seams: A case study in western China

Abstract

The Yangjiacun coal mine, located in western China, exhibits distinctive characteristics, such as its shallow depth, thick bedrock, thin loose layer, and unique roof strata breaking movement. In this research, a comprehensive analysis of previous exploration data, subsequent mechanical testing, key stratum theory, natural equilibrium arch theory, and simulation tests and numerical simulations has been conducted to investigate the failure behavior of the overlying rock strata in the Yangjiacun Coal Mine. Specifically, the load‐bearing capacity of the key stratum structure in the bedrock and the morphological properties of the arch‐beam structure have been thoroughly examined. A mechanical model of the roof rock arch‐beam structure has been established, and an analytical formula for the limit size and stability criterion of the arch‐beam structure has been derived. The mining‐induced rock arch‐beam structure plays a crucial role in transferring the load of the upper strata to the surrounding goaf, thereby preventing subsidence and deformation of the overlying strata. However, the arch‐beam structure periodically experiences instability during the advancement of the working face, gradually progressing towards the upper layer until the main key stratum is breached and the arch‐beam structure collapses. Based on the characteristics of weathered rock and the arch‐beam failure model in the Yangjiacun Coal Mine, quantitative backfilling mining methods have been proposed to either compensate for the mining void created by coal extraction or limit the size of exposed key strata through strip mining, ensuring the stability of the R6 key stratum. This study represents a significant contribution to understanding the intricate failure behavior of overlying rock strata in coal mines and provides a valuable framework for the responsible and efficient extraction of coal resources in similar environments.

Research on an Intelligent Mining Complete System of a Fully Mechanized Mining Face in Thin Coal Seam

“…By 2020, the proven recoverable reserves of thin coal seams were about 600 million tons, accounting for about 20% of the total coal reserves in China, and most of the thin coal seam resources are concentrated in the central and western regions of China, such as Sichuan Province, whose thin coal seam resources account for 51.8% of the coal resources in this province; Shanxi Province is one of the provinces with the richest thin coal seam resources in China [4]. Thin coal seam resources account for 17.6% of the province's coal resources, and the mining reserves of thin coal seam are 1.38 billion tons, mainly distributed in Datong, Ningwu, Hedong, Xishan, Luliang, Wutai, and Xinzhou; the thin coal seam resources in Shandong Province are mainly distributed in Xinwen, Longkou, Yanzhou, Zaozhuang, and Jining [5,6]. Thin coal seam resources account for 16.8% of the coal resources in Hebei Province, mainly distributed in Xingtai, Handan, Zhangjiakou, Chengde, and other areas; the thin coal seam resources in Anhui Province are mainly distributed in Huaibei, Huainan, Suzhou, and Fuyang [7,8].…”