Failure Mechanism Of Surrounding Rock And Support Technology Of Full-mechanized Mining Face In Shallow Coal Seam

It has important engineering application vaule to research on the failure mechanism and stability classification and support technology in shallow coal seam of northern Shaanxi.Depend on the crossheading support project in Shen-Nan mine area,the failure mechanism of the rectangular crossheading and supporting technology were researched by theoretical analysis,lab experiment,site monitoring and numberical simulation.The main work and conclusions are:?1?Analyzed the failure modes of the rectangular crossheading and the main factors which affect the stability of the roof.The main forms of damage are tensile damage,shear failure,local fall-stone failure and complex damage.The main factors that affect the stability of the roof are the geological conditions,the impact of mining,groundwater,section size,depth and ground stress.On this basis,established the mechanical model of the rectangular chute and analyzed the failure mechanism of the roof.?2?Combined with the main influencing factors of the roof stability,selected the saturated uniaxial compressive strength of the rock,the saturated uniaxial compressive strength of the coal,deep and span of the crossheading,and mining height as the indicators of roof stability classification.The stability of the roof is divided into?roof?sability?,? roof?medium sability?and roof?un? sability?.Based on the parameters of the original support,determined the support type by using suspension theory and compound beam theory.?3?The physical mechanics experiments of 1506 crossheading roof rock were carried out.Obtained The physical and mechanical parameters of coal and rock samples in natural and saturated state.Through the Analytic Hierarchy Process,the weights of each classification index are obtained.The fuzzy comprehensive evaluation method is used to determine the stability grade of 1506 and the roof stability is class??stable roof?.According to the measured datas,it can be seen that the deformation of the trough is small at 1506 and the maximum stress of the bolt is 30.2kN,and the supporting effect is better which meet the needs of face mining.?4?The finite difference software FLAC^3D was used to simulate the effect of all kinds of roof support in 5-2 coal seam.The results show that the range of deformation and plastic zone of all roofs are small during excavation and period of mining operation which meet the requirements of the crossheading support.The results of this study can provide reference for other mine crossheading support work in this area.