Abstract: A procedure for constructing a concrete lined underground chamber along a bore hole drilled within the earth. Such chambers serve as access work chambers for carrying out other various drilling and mining operations, such as, for example, horizontal drilling operations for steam enhanced recovery of oil. In constructing the lined chamber, the bore hole is initially drilled in the earth to a predetermined depth at which the chamber is to be constructed. In a first belling operation, a first bell-shaped chamber is formed. A substantial portion of the floor of this first chamber is then covered with a mound of gravel material. The remainder of the first chamber is then filled with concrete. Subsequently the bore hole is redrilled to a depth extending below the bottom of the first chamber and a second belling operation is carried out for forming a second bell-shaped chamber.

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.