Application of goaf-side roadway retained and new type ventilation system in deep longwall face

Goaf-side Roadway Retained (GRR) without coal pillar can achieve Y-type ventilation, mitigate outburst hazard of coal and gas, etc., the stability of which is the key basis of simultaneous extraction of coal and methane (SECM) for multiple coal seams with rich gas and low permeability. However, its long-term stability until the end of longwall face mining is extremely difficult to control and maintain under intense mining dynamic pressure, especially in deep coal mines. To achieve SECM for multiple coal seams with rich gas and low permeability in Zhuji Coal Mine, GRR with multiple segments innovating Y-type ventilation system is put forward and applied in 910 m deep longwall face. The numerical simulation model is established by means of Universal Distinct Element Code (UDEC) software to analyze the influence of filling wall width on the stability of GRR. The results show that 3000 mm wide filling wall is relatively appropriate. Engineering practice indicates the maintenance duration of GRR with multiple segments is greatly reduced, compared with that of traditional GRR and the deformations are effectively controlled. The amount of methane extraction was 14.49 m3 per ton of coal on average. SECM has been successfully achieved.