Experimental investigation on friction and squeezing of roof structure key blocks corner upon long-wall face

摘要

The coefficients of friction and squeezing of the key blocks comer in the roof structure of underground coalface are key factors to roof structure stability quantitative analysis. In this paper, through the special test of three-type comer friction and squeezing of real rock specimens, and physical simulation test on the roof key blocks of roof structure as well as the finite element calculation of the corner stress distribution and failure mechanism, the characteristics of friction and squeezing of the roof key blocks corner are revealed. It is found that the friction angle of the roof key blocks comer is the residual friction angle, and the frictional angle of the roof key blocks is 22-32 deg (average 27 deg), so the friction coefficient is determined as 0.5. It also found the squeezing strength is less than the uniaxial strength, and the squeezing coefficient of the roof blocks corner is determined as 0.4. Based on the results, the ground control theory can be updated from qualitative analysis to quantitative analysis.