| 摘要 |
This invention provides improvements through an engineered metal crib element for construction of cribs in mines to provide support between two surfaces and use of crib elements to construct cribs. The engineered metal crib element consists of a center elongate structural element and at least two outer load carrying steel members. The outer load carrying members may be composed of solid or hollow metal with one or more reinforcements within each load carrying member. Each outer load carrying member is attached to the center elongate element at the distal ends of the elongate structural element. The crib structure may be constructed by superimposing only these steel crib elements in 2×2 layers, 2×3 layers, 3×3 layers or in any other suitable layering system. The engineered metal crib elements are lightweight, have controllable higher stiffness and load carrying capacity than current wooden cribs, have engineered plastic yielding characteristics and allow much lower resistance to air flow in underground mine roadways.
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