Shallow Seam And Large Mining Height Fully-mechanized Working Face Overburden Structure And Pressure Mechanism Research

In recent years, large mining height technology has been widely used in Chinese largemining, is the main mining method in Shanbei mine and Dongsheng mine, however largemining height of roof structure and mining pressure mechanism is still not unified. Especiallyin the North of Shaanxi special thick overlying bedrock, double key stratum in shallow seamlongwall faces and roof structure of high pressure mechanism research. Master shallow revealroof structure, working face with large mining height has important theoretical and practicalsignificance to pressure mechanism.Based on the National Natural Science Fund Project "shallow seam and large miningresearch" structure and high stability of roof support, statistical analysis two minerals in NaLin Temple and2coal mines6m mining in Zhang Mao height working face pressuremeasurement and correlation of large mining height working face pressure on the basis of thecharacteristics, to carry out the4m,5m,6m,7m, large mining height working face miningroof structure of physical simulation experiment, combined with UDEC numerical simulationof shape roof structure, built of large mining height working face roof structure model,shallow longwall mining roof structure and roof high mining pressure mechanism systemresearch.Experimental study shows that the shallow coal seam working face with large miningheight support load with working face mining height increased linearly, the first weightingstep distance is usually35~70m, mainly distributed in50m; periodic weighting step distanceis usually9~20m, mainly distributed in15m. The dynamic load coefficient is1.2~2.0,generally1.5. The mining is larger,it will be more serious.Physical simulation and the numerical value computation found with mining height increase phenomenon of roof structure hinged position up, found in shallow seam double keylayer structure with different filling the present two kinds of structure form, the key layer ismainly formed "masonry beam" structure, mainly the key layer to "step rock beam" structure.By establishing the mechanical model, the stability of layer structure of the key line analysis,the main influencing factors affecting the stability of the key stratum is high, the roofstructure size, the loading layer thickness, the position of the hinge points (thickness andfilling of immediate roof). Finally, the mechanism of shallow seam of small periodic highworking face pressure is the key layer structure sliding instability, the mechanism of periodicpressure is the key layer structure instability leads to instability of superimposed effect slideinferior key stratum structure.