Research On Spalling Prevention With Coal Seam Injection In Front Of Working Face

Along with the increase of mining depth and wide application of large mining height fully-mechanized face and fully mechanized top coal caving mining with higher mining height,coal wall spalling is becoming severely.To guarantee the safety and high efficiency of working face,the coal wall spalling prevention is particularly necessary.This paper aims at the feature of large granule with difficult to inject subtle cracks of cement and high-cost、easy-exothermic of chemical grout,putting forward new type material which called colloid with the feature of easy-permeability、low-cost、 high-safety、cohesiveness,testing the viscosity、cohesiveness、permeability、shear force of the colloid and having a experiment in the colliery,the research results are as follows:(1)By viscosity test,concluding five colloid’s "viscosity-density" regular pattern,different colloid’s "viscosity-density" regular pattern is different,its viscosity is not positive correlation with concentration;the same material in different concentrations segment,the relation between viscosity and concentration is different.(2)By cohesiveness test,concluding improved strength of friable coal by five kinds of colloid respectively,SRJFis the best cohesiveness one,2% density SRJF can enhance compressive strength 1.36MPa of loose coal(diameter 1-2mm).(3)Manufacturing a injection model to test the permeability of colloid in the friable coal,by permeability test,finding that permeability of colloid is only related to viscosity,the penetration time is positive correlation with density scilicet viscosity;for the different materials while its viscosity is the same,the penetration time is the same.(4)By direct-shear test,concluding improved shear strength of friable coal by five kinds of colloid respectively,SRJF is the best one;2% density SRJF can enhance cohesion 80.45kPa of loose coal(mixing diameter 1-2mm and 3-4mm).(5)By experiment in the colliery Meng Jiayao,examining the,coal wall spalling preventing effect of D,forming a complete crafts that colloid injection in front of the working face-a coal wall spalling prevent method different to cement and chemical grout,concluding that colloid injection technology to prevent coal wall spalling is feasible.