Study on technology of gob-side entry retaining with hard roof in 1 000 m deep mine

In order to solve a maintenance difficult problem of the gob-side entry retaining caused by the high geostress of the deep mine shaft and the high additio nal stress superposition of the hard roof long suspended boom, based on the Ji 14-31010 coal mining face in Pingmei No. 12 Mine as a study object, a backfill wall con struction technique process of the gob-side entry retaining was analyzed and set up. An active pressure releasing technology with a pre-splitting blasting and a surroun ding rock enhanced control technical plan of the gateway retained along goaf were provided to control the hard roof structure as a target. The control effect monitoring and measuring results of the backfill wall construction and maintenance process for the gob-side entry retaining showed that after the pre-splitting blasting, the roof wei ghting step distance of the coal mining face was reduced about 10 m, the support load of the powered support applied in the coal mining face was reduced about 7 MPa and the roof weighting intensity was obviously reduced. With the enhanced control of the gateway, after the gob-side entry retaining stabillized, the cross section conver gence of the gateway was 34% and the cross section area was over 10m2. Thus the normal ventilation of the coal mining face and the pressure releasing and gas drain age space requirement could be ensured and the gob-side entry retaining was successfully applied under the condition of the high geostress and hard rood in the deep mine shaft.