Study on layout optimization of seam gateway under contiguous seams

In order to set up the rational layout location of the seam gateway under the downward mining in the contiguous seams,a numericalsimulation,theoretical analysis.foor frictional experiment and site test method were applied to the nalysis on the foor stress distribution law of he remained coal ilar,stability of the sectional coal pillar,suounding rock deformation failure features of the gateway and others. The study showed that No.10 seam mining caused the foo failure depth spread to the level of No.11 seam gateway.The stress reduced zone had a horizontal distance of 7 m to the retained coal pilar in the upper seam mining . Infuenced by the secondary mining.the failure width of the sectonal coal pilar in No.11 seam was about 4 m and the rational iner ofiset distance in the gateway layout should be over 11 m.When the inner ofiset distanceof 14 m and 20 m applied to the gateway layout in the sinmulation experiment,the surounding rock could keep a same degree good stability. In order to improve resource mining rate,the inner offset distance of 14 m selected could ensure a safety mining operation.Finally a monitoring and measuring on experiment section was conducted in No.113 cal mining face and inner offset distance of gateway was selected as 15 m conservatively.The site measurement results showed that under the layout condition,the stability of sectional coal pillar was good,the convergence between two sidewalls along the gateway was 30 ~ 220 mm,the convergence between the roof and foor was 20~110 mm and the surrounding rock deformation of the gateway could be well controlled.