Study On Overlying Strata Motion And Demolish Law And Roadsie Supporting Parameters In The Secondary Gob-side Entry Retaining

The conventional first gob-side entry retaining is after the upper section coal face mined, through the methods of reinforcement, this will be the original conveyor road-way to the next section ventilation roadway, namely "the roadway with two uses". The secondary gob-side entry retaining is on the basis of the first gob-side entry retaining, the roadway to retain, after the under section mined to retain, as the roadway of mine goaf gas extraction.Based on the method of theoretical analysis, similar material simulation and numerical simulation, studied on the secondary gob-side entry retaining of thin seam for support technology beside roadway,main results are as follows:â‘  By experiment with triaxial compression in coal and rock mass,by used MTS815 hydraulic servo system,obtained the basic physical and mechanical properties in coal and rock mass.Conducting of experimented with uniaxial compression in coal and rock mass,by used SHIMADZU testing machine.At the same time on the charact-eristics of acoustic emission in the process of damage detection, Obtained the stress-strain curve and the relationship between acoustic emission in coal and rock mass.â‘¡ Based on similar material simulation and numerical simulation experiment, Studyed the evolution of stope surrounding rock stress and displacement, the research shows that:1)After the secondary gob-side entry retaining about dalong coal seam, Formation of stress concentration in on both sides of the roadway,the maximum stress of 53.92 MPa, deformation of roadway has increased dramatically, maintenance difficulties. 2)Affected by the upper dalong coal seam mining,the surrounding rock stress declined, the maximum stress of the secondary gob-side entry retaining was 37.92 MPa,relative ly dalong seam had fallen by 29.67%,creat the advantage conditions of roadway supporting.â‘¢ Established a mechanical model for secondary gob-side entry retaining by the theory analysis, obtained the support resistance on the calculation formula. According to the test of roadway concrete parameters, obtained the support resistance on relations with support width on the secondary gob-side entry retaining. Established a mechanical predict models of immediate roof subsidence on the secondary gob-side entry retaining,under the condition of main roof of confined deformation, obtained the subsidence calculation formula on the secondary gob-side entry retaining.â‘£ Studied on the influence of different supporting parameters of stress and displacement evolution rule on the first gob-side entry retaining and the secondary gobside entry retaining. The results show that:1)The lower intension of supporting material brought roadway of smaller stress distribution, and the roadway support stress smaller,but the supporting itsself bearing capacity is low,caused the secondary gob-side entry retaining deformation is bigger.Similarly,the higher intension of supporting material brought the stress of whole surrounding rock had risen,the deformation of surrounding rock reduced.2)The aspect ratio has some effects on surrounding rock stress,due to the unstability of the lower aspect ratio of supporting body itself, leaded to unstability,the surrounding stess is lower,serious deformation.The bigger aspect ratio of supporting body cause higher surrouning rock stress,less deformation.Therefore,the rational supporting aspect ratio and intension played a key role in maintaining the stability of the roadway.