Abstract: A high pressure bag for pre-stressing a support pack in an underground mine has a fluid impervious liner and three tubular envelopes. The liner is located in the first envelope with end portions of the first envelope and edge strips of the liner folded over underneath the first envelope. The first envelope with the liner therein are in the second envelope, with end portions of the second envelope folded over on top of the second envelope. The second envelope is located within the third envelope which has opposed edges stitched closed. The liner has a nozzle which extends through openings in the envelopes.

Abstract: The yieldable load support comprises a compressible support member in the form of an elongate timber pole. The load support or pole is asymmetrically modified at or near one end thereof in a manner to positively induce sideways brushing of the pole at the modified end, in a preferential direction transverse to the length of the pole, when the support member is placed under longitudinal compressive load of sufficient magnitude.

Abstract: This invention relates to a composite type mine support pack and a component for building the pack. The pack components are identical with each including an elongated timber element, a first brick which is attached to the element adjacent its one end and a second brick which is attached to the element on the same side of the element and in alignment with the first brick in the axial direction of the element with the second brick being spaced from the other end of the element by a distance equal to twice the dimension of the first brick when measured in the axial direction of the timber element plus the distance by which the first brick is spaced from its end of the timber element. Preferably the bricks are made from timber. The pack consists of superimposed layers of the components with the bricks on each component resting on those of the components above and below it.