Atlas Copco Aktiebolag

Atlas Copco Actiebolag

Bo T Skogberg

Gunnar V Romell

Bengt P Granstrom

An expansion body for constructions like piles or anchorages located in the earth is adapted for insertion into the ground in a compact shape and expanded therein to an expanded shape. The expansion is achieved by unfolding a folded metallic casing (11) by filling it up with pressurized fluid. Each end of the elongated body is sealed by a closure comprising a socket (16, 17) with a sleeve (18, 19) encircling the near end part of the casing and a bottom plate (20, 21) with spacing means (22, 23) projecting into the inside of the casing. The sleeve (18, 19) and spacing means (22, 23) define an annular space (26, 27) in which the end parts (14, 15) are kept in a folded position when the body is expanded.

Expansion body

A tube-formed rockbolt is partly circular in its cross-section and opposite its circular portion (12) it has a deep depression (16-18). Its ends are sealed and its outer end has a hole (44, 45) or a fitting (24) through which the bolt can be supplied with high pressure water that expands the tube to anchor it in the borehole.

Method of rock bolting and tube-formed expansion bolt

An expansion body for constructions like piles or anchorages located in the earth, said body being adapted for insertion into the ground in a compact shape and expanded therein to an expanded shape. The expansion is achieved by unfolding a folded sheet metal casing (11) by filling it up with pressurized fluid. The sheet metal casing which defines two opposed portions (16, 17) is folded in a zigzag shape before the expansion with the folds (18) of one portion (16) falling into the folds (19) of the other portion (17).

Earth anchoring expansion body having folded sheet metal casing

A rock bolt is manufactured from a steel tube which has been deformed to have a deep depression so that it assumes a substantially reduced diameter. A sleeve is pressed onto the outer end thereof which is sealed through welding. An installation chuck carried on an installation rod comprises a socket for receiving the outer sleeve and when the rock bolt has been manually inserted in a borehole, for example by means of the chuck, high pressure liquid is conveyed through passages in the chuck to a hole which leads through the sleeve to an interior chamber of the tube so that the tube expands through plastic deformation, thereby anchoring the rock bolt in the borehole. The chuck is then relieved of pressure and removed from the anchored rock bolt.

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Handen, Sweden

Bo T Skogberg