Importance

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Abstract

In conjunction with the mining of minerals from the earth, it is necessary to construct deep verticle shafts normally between 10 and 20 feet in diameter and typically between 3000 and 6000 feet in depth in the earth. Technology has been developed for blind drilling of such shafts. After drilling the shaft however, in order to protect those entering the hole for additional mining operations the shaft needs to be lined with a stack of specially constructed lining segments. These segments are formed of prestressed concrete. The concrete segments are lowered one at a time into the bore hole shaft, which is filled with fluid, so as to build up a stack within the hole, thereby lining the hole. Each concrete segment has a top portion with an approximately V-shaped cross-sectional area with a flat top section and a bottom portion having an asymmetrically cross-sectional shape but such shape partially corresponding to the shape of the top portion so that the segments can be stacked. As the segments are stacked, an uneven turbulence is created due to the shapes of the top and bottom portions of the segments. This turbulence helps to flush out any particles from between the concrete segments. Grout is then placed between the lining segments and the inner wall of the bore hole. The grouting process is periodically carried out after every few segments have been placed into the hole. After the lining operation has been completed, the fluid is pumped out of the hole and then the miners can enter the hole for other mining operations.

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First Claim