Study On Three Zone Height Distribution Characteristics Of The Thick Sandstone Roof About Xinji2Mine Gob

Due to the influence of the Mined-out area,the three parts are formatted in the upper rock:the caving zone,fractured zone,bending subsidence zone,the observation of the three zoneabout the Mined-out area is very important for the safety production of coal mine,it hasgreat practical value for the arrangement of high drainage and gas drainage arrangement,Firstly, the basic concept of "three zones", formation mechanism, influencing factors, thestandard divided by the force, the advantages and disadvantages of traditional three-bandobservation methods described detailly in this article.Special research on thick sandstoneroof is less,theoretical analysis of the thick sandstone roof is recommended in thispaper,while traditional method of three-zone can not meet modern needs,intuitive andaccurate visual research is not received,the new observations of three band method is usedto observe,namely the borehole camera,providing new observation techniques and methodsfor the safety of coal mining.In this paper,theoretical formula,numerical simulation,field measurement of boreholecamera are used to analysis comprehensively the three zones of the development anddistribution of xinji two coal mine,the height of the three zones is determined.The domesticand foreign achievement of more mature experience formula and the engineering analogyare used in theoretical analysis,the thick sandstone roof of the1thick coal height on thethree zones is calculated,the caving zone is16-20m,fractured zone is60-88m;By FLAC3Dnumerical simulation a mining model is established, elastic-plastic graph、stress contours、displacement contours are calculated,the variation of different lithology and different roofthickness are analysised,the five different model characteristics of the thick sandstoneabout xinji two coal mine are getted,the caving zone is23m,obvious fractured zone is44m,fractured zone is84-88m; new technology of borehole camera is used in fieldmeasurement,the three zone height based on the measured data is analysised to verifytheoretical and numerical simulation results,the caving zone is21.0m,obvious fracturedzone is38m.The height distribution of three zones about thick sandstone roof iscomprehensivly analysised,the caving zone is21-23m,obvious fractured zone is38-44m,fractured zone is84-88m, providing the basis for further study on the movement ofoverburden rock and guidance for the safe exploitation of coal and gas drainage.