ry clearly the causes and nature of thetrouble and the means taken to remedy it. The bot-tom of the tunnel is 60 feet below the street surface.The heading at this point is 12 feet in height by 30feet in width. The distance from the roof of the toward the surface. On either side of the rock wasa… … CAVE-IN, SHOWING THE METHOD OF REPAIRS BY BULKHEABINGANB GROUTING. 4-foot layer of rock and allowing it to slide bodilyinto the tunnel. In spite of the endeavors made tostop this sliding by heavy shoring, the timbers werecrushed in anda section of theroof 70 feet inlength by sev- 63 Pft like…
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