Research On Load Transfer And Support Crushing Mechanism Of Thin Bedrock Stopes Under Loose And Thick Aquifer

In recent years,East China has happened dozens of supports crushing accident when mining coal under thick loose aquifer layer,And these accident have an increasing trend in fully mechanized mining face,have caused significant economic losses and bring seriously threat to coal mine production safety,has attracted the attention of industry leaders and scholars.Loose aquifer often accompanied by abnormal increase of roof pressure appear,supports crushing and working face water inrush periodically in the advance of working face,therefore,in view of this situation,this paper research on thin bedrock overburden rock structure and supports crushing mechanism simulation use theoretical analysis and field comparative experiments.According to the simulation experiment results established the mechanical model of surrounding rock and support and the impact of loose aquifer load transfer characteristic on rock breaking mechanism under the condition of different key stratum combination have been analysised,the results show that:(1)The influence of aquifer on single key stratum is greater than few key layers which exst in thin bedrock over working face.Single key stratum also bear load of thick overlying alluvium pressure transferred by confined aquifer and caving rock load which exsts between the aquifer and the key stratum,this leads to a single key layer can not form a stable supporting capacity of the voussoir beam structure,and prone to sliding instability,causing the working face pressure frame supports crushing.(2)The distance between two key layers will directlly affect the voussoir beam structure stability formed from broken key stratum under the affct of aquifer:①If the spacing is too small between two key stratum,double key stratum will occur compound breakage easilly.The underneath key stratum will not form a stable structure of voussoir beam;②If the distance is large enough,the underneath key stratum will form stability voussoir beam structure above filled goaf after the key stratum breaking in the advance of coal mining,and the voussoir beam structure is protected by natural archwhich has been formed by the caving rock beneath upper key stratum,the natural arch blocks the load of loose layer and aquifer water pressure from exerting on voussoir beam structure,and the voussoir beam structure will not easilly sliding instability when the heavy load exert on it,supports crushing accident will not easilly happen in working face.At the end of the paper,taking fully mechanized mining face of Gubei mine 1202(3)and Pan er mine 1811(1)as engineering background,By comparing and analyzing the characteristics of strata pressure in the field mining process,furthermore,the results of the study on the mechanism of the working face supports crushing mechanism under aquifer load transfer is analyzed in different key statum combination,The results of the study provide a theoretical basis for the safe and efficient exploitation of mining have similar geological conditions.