Lessons Learnt from Measurements of Vertical Pressure at a Top Coal Mining Face at Datong Tashan Mines, China

Excerpt

Mining mechanics usually refers to the movement of overburden rocks and stress redistribution induced by mining effects, especially during the evolution of abutment pressure at a mining face (Xie et al. 2011). The characteristic of the stress field at a mining face serves as an important foundation for achieving roof safety and preventing excess gas (Suchowerska et al. 2013; Yang et al. 2011a). The mining effect may cause coal rocks to fracture, causing coal methane to escape from the fractured rock into the mining face, resulting in the exceedance of safety limits for gas. This is especially relevant under intensive mining conditions (Yang et al. 2011b; Li et al. 2006; Wang et al. 2012). Therefore, the study of mining mechanics is of great importance in achieving the safe and efficient coal mining. Many specific studies have been conducted to investigate stress redistribution, strata deformation, strata failure and fluid flow of coal seams (Islam and Shinjo 2009; Yang et al. 2014). However, these studies only focused on mining mechanics induced by mining advances, and neglected local mining effects, such as coal caving processes used for top coal caving method. In this manuscript, a field test and analytical analysis were conducted. A combination of global and local mining mechanics was consequently proposed for the top coal caving. Based on the real-time pressure monitoring of single props and hydraulic supports at a top coal mining face, intensive factors of pressure were adopted to provide a quantitative description of the mining mechanics. …