Study On Failure Mechanism Of Floor Heave And Supporting Technology Of Soft Rock Roadway In Shanghai Miao Mining Area

The management of roadway floor heave has always been one of the key problems in the safe and efficient mining of coal mines.With the depletion of shallow resources in the Middle East mining area,the focus of coal mining has the trend of transferring to Shaanxi and Inner Mongolia,and the development of the western mining area will become a new development direction.At present,most of the Coal Seams Mined in the western mining area occur in the Mesozoic strata with late diagenesis.The surrounding rock is poorly cemented,strongly deformed,softened and argillated when encountering water,and continuously deformed.The floor heave problem is particularly prominent.A large number of soft rock roadways still have some ambiguity in understanding the mechanism of floor heave,which leads to blindness of technique controlling floor heave and dependence on experience,leading to the failure of floor heave control.Therefore,the research and development of the mechanical mechanism of floor heave and the corresponding technique controlling floor heave under the specific geological conditions have extensive application value and important practical significance.Basis On summarizing the mechanism and control technology of floor heave at home and abroad.taking the severe compound floor heave phenomenon along the channel of 13803 working face of-400m level in Yushujing coal mine as the background.adopting the methods of on-site ground pressure observation,laboratory test,theoretical analysis and FLAC3D simulation to study the influencing factors,mechanism of mechanical action and the corresponding floor heave control technology Research.The research and results are as follows:(1)Based on the analysis of mineral composition and physical and mechanical tests of the rock samples collected on site.it is concluded that the main mineral composition of the surrounding rock of the roadway roof and floor are kaolinite and Illite.the uniaxial compressive strength of the surrounding rock of the floor is 3.94MPa.the tensile strength is 1.21MPa,the average softening coefficient is kept between 0.09～0.12,and the overall strength of the surrounding rock of the roadway is relatively low,which belongs to a typical weak cemented soft rock Tunnel.Through the analysis of the influencing factors of the floor heave of the soft rock roadway.it is concluded that the floor heave of the soft rock roadway is the result of the coupling action of the properties of the surrounding rock of the roadway.the supporting pressure of the coal pillar,the form and parameters of the mine water and the improper support.It is determined that the floor heave type of the roadway is the composite floor heave composed of the extrusion flow of the shallow soft rock and the shear dislocation of the deep thick layered medium grained sandstone.(2)On the basis of fully considering the stress action mode,load of fractured rock mass and macroscopic deformation characteristics of 13803 track trough floor,combined with Rankine pressure theory and platts arch theory,a mechanical model of roadway floor heave of shear stagger type in soft rock roadway was established.The bottom heave problem of 13803 track is analyzed from the perspective of mechanics.and the ultimate depth yo at the zero displacement point of the bottom plate is determined to be 1.7m.The study of roadway floor heave pressure P0 is 33.6kN provides a theoretical basis for the development of floor heave control technology.(3)A new control technology of anti-bottom arch floor dropsy,which is suitable for the mechanical mechanism of the generation of shear floor dropsy,is proposed,and the mechanism of each part in the process of floor dropsy control is analyzed by combining theoretical analysis and FLAC3D numerical analysis.The optimal parameters of technique controlling floor heave be optimized,which provided the basis for the field industrial test.(4)The industrial test of the new anti-bottom arch floor heave control technology was carried out in the 13803 track of Yushujing coal mine,and the surrounding rock movement law of the roadway in the test section was monitored and analyzed.The final average roof subsidence of the roadway in the test section was 104.1mm,the convergence of the two sides was 151.5mm,and the maximum floor heave was 71.5mm.The support scheme effectively maintained the stability of the roadway during the service period and achieved good engineering results.