Importance

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Abstract

This invention provides improvements through 1) a composite, engineered wooden support element for construction of cribs in mines to provide support between two surfaces, 2) use of support elements to construct cribs, and 3) a wedge system to provide substantial sustained preload on a crib. The wooden support element consists of a center elongate element wherein the wood grain runs transversely to the crib element loading direction, and at least two outer plate elements wherein the wood grain runs axially with the crib element loading direction. Each outer plate element is attached to a surface of the center elongate element using fastening means and the outer plate element wood grain direction is aligned transversely to the grain direction in the center elongate element. The crib structure may be constructed by superimposing only these support elements in 2×2 layers or in conjunction with solid prismatic wooden elements. A wooden wedge system with relatively low angle surface and with wood grain running axially is utilized to apply vertical preload. Due to high stiffness of the wedge in the axial direction, a substantial vertical preload can be applied and sustained to make cribbing structure a more efficient load carrying structure. The wooden support elements are lightweight, have controllable higher stiffness and load carrying capacity than current cribs, engineered yielding characteristics and allow much lower resistance to air flow in underground mine roadways.

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First Claim