In this paper, the effect of the remaining coal pillars in a room-and-pillar section on the long-wall face in the lower coal bed are tested by using equivalent material models. The failure laws of the overburden under coal pillars are discussed. A phenomenon of sub-weighting has been observed when long-wall face is in process under the remaining pillars in room-and-pillar mining section. It is concluded that, because coal pillars underwent a course of the stress increasing before they were fully destroyed, the existence of the coal pillars would shorten the distance of periodical weighting of the main roof in the long-wall face. Based on this, the characteristic equations of the overburden movement under coal pillars are presented.
展开▼
