Roadway layout for recycling residual coal pillar in room-and-pillar mining of thick coal seam

In the context of a room-and-pillar mining gob in Shanxi province in China, this paper numerically investigates the stress distribution and deformation rules of roadway surrounding rocks at various locations of residual coal pillars in room-and-pillar mining gobs using software FLAC3D. It is found that the concentrated stress beneath coal pillars distributes in a shape of ellipse. A reasonable roadway layout is then proposed. In this design, it is indicated that roadways should be designed to avoid the supporting zones of pillars with increasing compression and take into account the roof falling and crushing in the upper gob. According to the surrounding rock deformation characteristics and mining roadway locations as well as the supporting principles of timely support, rock reinforcing, piecewise management and suiting local conditions, a new asymmetric shield supporting plan is proposed. The field surveying results show that this supporting plan can effectively control the roadway rock deformation, thus guarantee the safe and smooth construction of roadways.