High-intensity longwall mining-induced ground subsidence in Shendong coalfield, China

Abstract

Ground subsidence caused by underground coal mining is one of the challenging environmental issues in mining engineering. This paper presents a field monitoring study of longwall mining-induced ground subsidence in Shendong coalfield, China. The paper includes the subsidence data of four longwall panels, with mining and geological conditions varied. All the longwall faces have a high mining height (4.5-7 m) and extraction speed (9.0–13.3 m/day), but with shallow mining depth (180-210 m). High-frequency field observations allow the dynamic characteristics of the ground subsidence caused by high-intensity longwall mining to be captured and revealed. Results show that, for a longwall panel with a width to depth ratio of 1.35–1.6, the subsidence ratio is generally between 51.1–54.3%, and the maximum subsidence speed can reach 0.4 m/day. Furthermore, the overlying goaf considerably increases the subsidence ratio, and the instability of the boundary coal pillars decreases the ground surface deformation but increases the range of influence. Results also suggest the use of dynamic surface subsidence to infer the breakage and movement laws of the strata in the high-intensity longwall mining condition. Finally, the practical implications of the results and the associated environmental effects are briefly discussed.