Working in Quicksand.

Working in Quicksand.

One of the most ingenious expedients for overcoming the difficulties of sinking shafts for mining or other purposes in wet “measures” is the “freezing process.” Supposing that the bottom of a shaft is so continuously flooded that the miners are unable to use their picks or in any way proceed with their excavation, pipes are run down from the surface of the flooded locality, and through these pipes is forced a powerful freezing mixture. The consequence is that the impeding water becomes solidified, and the workman can quarry his way through the ice. which now becomes a protection from the body of water beyond, and the sinking of the shaft can be continued. A process somewhat akin to this is the new method of grouting up quicksands, etc., of Neukirch. Where quicksands or damp and unstable strata are encountered powdered cement is forced in by air pressure through a pipe lowered in the sand. The pipe is about one and one-half inches in diameter, but is drawn to a point at its lower end, where there are three openings, each three-eighths of an inch in diameter. The upper end of the pipe is connected to an air-pressure supply by a rubber hose. An injector is provided, to which the cement is fed, and, meeting with the air blast, is driven with considerable pressure into the sand. The cement is retained by the wet sand, forming a kind of concrete with it. The introduction of the tube is facilitated by the use of the air jet, which clears the sand away from the point of the tube. When the pipe has reached a firm stratum the cement is turned on and the pipe slowly raised to the surface.

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