Research and application of key technology to deep mine gob-side entry retaining

in order to solve the dificult problem of gob- side entry retaining in the deep mine,according to the deep depth of 800 m in Chensilou Mine as well as the geolgical conditions of the coal mining face with gob-side entry retaining and the deformation failure featuresof the gateway.with the theoretical analysis,the deformation falure law of the gateway was found.An active combined support technology of the gateway withan advanced pilar + high strength grouting + high strength and low density anchor was provided to keep the surrounding rock integraity of the original rectangular gateway and the self suficient loading capacity.The active and passive combined support technology of the two sidewalswih" the high strength double grouts backilld wall + bol( anchor) cross supplement support +densepilars" was applied in order to improve the stabiliy and compressive strength of the backilled walls of the gateway sidewall he results showed that after the key technology of gob-side entryretaining applied to No.21701 coal mining face in the deep depth of Chensiou Mine,the surrounding roek deformation of the gateway was effectively controlled,the surounding rock deformation of gob-side entry retaining was in stable after 60 days,the max subsidence of the roof was 126mm,the max convergence between the two sidewalls was 243 mm and the max foor heave value was 532 mm.A normal operation of the gatewayduring the safety production process was ensured.