Improvements in or relating to the roofs of colliery or other workings

摘要

554,077. Mine-roof supports. BEIJL, Z. S. Dec. 16, 1941, No. 16235. [Class 20 (ii)] To prevent the lateral movement of the strata which normally occurs in the roof of a mine, the strata are secured together by bolts which by their tension prevent collapse of the roof and consequent lateral strain relief ; the bolts may carry a system of horizontal cross-members beneath the roof. The strata of the roof are bored and bolts 1 are driven through the strata, each bolt being provided with self-gripping means at its inner end. Each bolt may also support corrugated washers 2 and hangers 4 on the ends 9 of which may be carried the ends of corrugated bars 5 which support further transverse corrugated bars 6, the whole being tightened against the roof by a nut 8 and washer 3. A sufficient number of bolts 1 are disposed in the passages to efficiently support the beams 5, 6 for the roof, and further short supports 10, Fig. 5, are disposed on each side to engage ledges on the upper portions of the wall face 11. In working on a face 12, rows of bolts are disposed in the roof at A, B, C, D, a cut 18 is made at the base of the wall and the wall face is then removed, after which a fresh set of bolts E is positioned nearer to the new wall face and the conveyer 14 is repositioned for further work. The roads are retained by packs 13 which are built to support the roof after excavation.