This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: ...shovel, useful in a tunnel, is of course out of the question in the bottom of a sinking shaft. Drilling and Blasting.--The universal method of shaft sinking in rock is to drill a number of holes in the bottom, charge them with dynamite and shoot them, and to load the broken rock by hand into shaft buckets which are ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: ...shovel, useful in a tunnel, is of course out of the question in the bottom of a sinking shaft. Drilling and Blasting.--The universal method of shaft sinking in rock is to drill a number of holes in the bottom, charge them with dynamite and shoot them, and to load the broken rock by hand into shaft buckets which are then hoisted out. When all the loose rock has been removed the process is repeated. As it is very difficult to drill holes through loose rock, the broken material must be all removed before the next round of holes is started. This creates an additional difficulty for the mechanical digger, for while a grab might be made to remove most of the loose rock after a blast, hand work would still have to be resorted to to get the bottom ready for drilling. Shafts are drilled on the "center-cut" principle. Eight or ten holes are drilled on a slant, separated at the top but converging, thus forming a wedge known as the "sump." "Reliever," or bench, holes are drilled back of the sump holes, each row being more nearly vertical; the end or outside holes point slightly away from the vertical and toward the wall line of the shaft. The sump is first shot and the broken rock removed or "mucked" out, forming a cavity into which the bench rounds can be successively shot. All muck should be removed before each succeeding round is shot. Fig. 29.--Shaft (a) Fig. 30.--Shaft (6) Two systems of drilling and mucking exist. In the first the holes for the entire cut--sump and benches--are drilled at one time, the sump is shot, and then the benches as required. In the second the sump only is drilled and shot, and the benches are drilled while the sump is being mucked. The first plan is particularly applicable to small shafts and to cir...
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PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
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Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
