Analysis of key block in the structure of voussoir beam in longwall mining
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文摘
Based on analysis of the complete structure of a voussoir beam in longwall mining, the key block, which affects safety of production at work face, is simplified into an arch with three articulations. Basically, there are two modes of instability, namely instability due to sliding(S), and instability due to rotation(R). The major factors that affect the stability of the structure are rotational angle of the voussoir beam, ratio of length and height, rock type and height of carrying rock strata. Based on detailed analysis of these factors and their range, the theory of ‘S-R’ stability for rock structure in mine workings is preliminary established.