Application of Precracking Blasting Technology to Prevent Large Area Overhanging Roof in Working Face
Large overhanging roof caused by difficult caving of thick hard roof during initial mining is a common safety hazard in coal mine mining.In order to avoid the heavy and hard basic roof of 2505 fully mechanized caving face which is difficult to collapse during the initial mining period,the gun hole layout para meters of 2505 fully mechanized caving face roof precracking blasting are obtained through theoretical calculation and applied in the field.The results show that the blasting para meters with the spacing of drilling holes within the group is 6 m,the spacing between groups is 16 m,and the vertical processing height is 15.8 m can effectively destroy the integrity of the thick hard roof.After blasting,the top coal immediately collapses behind the support,and the working resistance of the hydraulic support changes periodically with mining.There is no phenomenon of large hanging roof in the subsequent mining process of the working face,ensuring the safe production of the working face.
thick hard rooflarge overhanging roofblasting precrackingworking resistance
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