Abstract In rock surrounding an underground excavation which must have a man-made support system to ensure a required degree of structural stability and which is subjected to certain stress conditions, an inflatable device or rock jack is inserted into a drill hole or slot in the rock. The rock jack is inflated slightly by fluid pressure to take up any space between the jack and the in situ rock and is subsequently pressurized to the limit of its capability. High compressive force is transmitted to the rock, thus creating compressive stress in monolithic rock and increasing confinement of and friction between proximal blocks of rock which are separated by narrow fractures, tension cracks, joint planes or similar structural defects. Such action maintains or increases the natural capability of the rock to support itself and to remain stable by utilizing the inherent compressive strength of the rock.
Jack means for insertion into a drill hole for counterstressing in situ rock in structural support of an underground opening comprising a flattened tubular member constructed of a non-elastic material, said tubular member being deformed over substantially its entire longitudinal length and sealed at one end, and valve means attached to the other end of said tubular member for introducing pressurized fluid into said tubular member once it is inserted into said drill hole, said tubular member being adapted to revert to its undeformed state when sufficiently pressurized, thereby exerting a compressive force radial to said drill hole and tangential to said underground opening.
Claim 2
Dependent Claim
104 words
Jack means for insertion into a drill hole for counterstressing in situ rock in structural support of an underground opening comprising a flattened tubular member constructed of a non-elastic material, said tubular member being deformed over substantially its entire longitudinal length and sealed at one end, and valve means attached to the other end of said tubular member for introducing pressurized fluid into said tubular member once it is inserted into said drill hole, said tubular member being adapted to revert to its undeformed state when sufficiently pressurized, thereby exerting a compressive force radial to said drill hole and tangential to said underground opening.