Study on supporting technology of narrow coal pillar driving along gob in medium-thick coal seam

In order to reduce the amount of coal loss in fully mechanized mining face and ensure the supporting effect, the width of coal pillar and support scheme of the auxiliary transportation lane in the No.30100 face of the 3-1 coal seam of Nanliang Coal Mine was taken as the research background, using theoretical analysis, numerical simulation and field measurement,the minimum width and supporting scheme of coal pillars in fully mechanized coal mining face of Nanliang Coal Mine are studied.The study shows that when the depth of roadway is 100 m, the mining height of coal seam is 2 m, and the support resistance of roadway coal rib in gob of the narrow coal pillar is 0.25 MPa, the distance between the location of the basic roof fracture line at the gob side of narrow coal pillar and the coal wall at the gob side is 2.53 m, which is also the width of the plastic zone in which the gob affects the stability of the narrow coal pillar; when the width of the plastic zone affecting the narrow coal pillar in the gob is 2.53 m, the effective length of the anchor in the narrow coal pillar is 1.5 m, and the depth of roadway is 100 m, the width of narrow coal pillar in the No.30100 working face of No.3-1 coal seam in Nanliang coal mine is determined to be 5 m according to the limit equilibrium theory; for narrow coal pillars with a width of 5 m, it is determined that the support scheme of roadway is bolt support at the side of narrow coal pillar, combined with support of roof bolts and anchor cables. The bolts on the side of the narrow coal pillars are ø16 mm×2 000 mm, the spacing between rows is 900 mm×1 000 mm, the anchoring length is 600 mm, and 3 bolts are arranged in each row; the top of the roadway is ø20 mm×2 200 mm type left-handed threaded steel bolts (the spacing between rows is 1 000 mm×900 mm, 5 in each row), combined with ø15.24 mm×6 000 mm anchor cable (row distance is 2.0 m). Field measurement shows that the width of narrow coal pillar and support scheme can meet the safety requirements of roadway tunneling and mining of working face in Nanliang coal mine, and it has great economic benefits, which is worthy to be popularized in mines with similar conditions.