Experimental Research On Gas Permeability Of Coal Gangue Backfilling Under The Circumstance Of Protective Layer Mining

It has an affect on the laws of gas migration when taking coal gangue backfillmining,and there’re clear differences between the coal gangue backfill mining and the directcollapse mining which in terms of permeability of coal.Therefore,an experimental system formeasuring gas permeability of coal gangue backfilling is developed independently, and gaspermeability of coal gangue backfilling on the condition of diverse parameters can bemeasured by using it.Based on the theory of coal gangue backfill mining and gas permeationat home and abroad,using the methods of lab experiment，field testing and numericalsimulation, this article studies the factors that influence on gas permeability of coal ganguebackfilling under the circumstance of protective layer mining.The achievements of this thesisare as follows.1) By analyzing the theory of coal gangue backfill mining and gas permeationsystematically, the reasonable calculating method of gas permeability of coal ganguebackfilling under laboratory conditions is identified.2) An experimental system for measuring gas permeability of coal gangue backfilling isdesigned which is based on differential pressure method and Darcy’s law，the experimentalsystem is composed of pressure loading system，gas supply system，measuring system andvapour recovery system，and it’s detailed operating steps is come up with.3) The relationship that grain composition of coal gangue，pressure of surrounding rockand gas density with gas permeability of coal gangue backfilling is obtained through theexperimental research on gas permeability of coal gangue backfilling on the condition ofdiverse parameters. Furthermore，the gas permeability coefficients of coal gangue backfillingmeasured by the experiment are in the interval of [0.649，3.206]m2/(MPa2·d)，which belong tothe interval of can be gas drainage．4) In order to increase the gas permeability of coal gangue backfilling, the mothods ofincreasing the grain composition of coal gangue and the ventilation quantity between workingface ends can be adopted when using coal gangue backfilling mining.5) The gas flow patterns of filling mining goaf under different filling thickness aresimulated by means of Fluent numerical analysis software, the conclusions of experimentaland numerical are applied to field practice, and the filling plan of Huoshaopu mine23123working face goaf is designed.