Rockburst Prevention Mechanism Of Rigid-flexible Coupling Support

Deep resource mining is imminent because the shallow resources are increasinglyexhausted worldwide. However, with the increase of deep mining, buried tunnel andother underground human activities, the geostress increases nonlinearly, the temperaturerises quickly, and geological environment is more complicated. At the same time, rockbroken and supporting overall instability and failure caused by impact energy bringgreat harm to people’s lives, properties and industrial safety. It is necessary to make asignificant breakthrough in the new materials and methods of rockburst preventionsupport. Therefore, it has the important theoretical significance and practical value toestablish rigid-flexible coupling support model, reveal energy absorption mechanism,put forward rigid-flexible-rigid coupling support method and provide a new material andmethod for rockburst prevention support. The rigid-flexible coupling energy absorptionmechanism and rockburst prevention support method are studied by using theoreticalanalysis, impact test, similar simulation experiment and numerical calculation method.Experiments study the mechanical behavior, energy-absorption ability of porous metalmaterials and rockburst prevention support effect under the condition of quasi-static andimpact load. Theoretical analyses show the stress criterion and energy conditions ofsurrounding rock in rockburst roadway, establish rigid-flexible coupling mode(rigid-flexible-rigid coupling support system: R-F-R), and study the theory of rockburstprevention support. Similar material simulation experiments research the process ofrockburst, the roadway deformation law and the supporting effect of different supporttypes. Numerical simulation studies the deformation law of roadway under high-speedimpact load, and the roadway damage degree under different supporting conditions. Atlast, it proves the reasonableness and effectiveness in roadway support. Based on themechanism of rockburst prevention, the rockburst prevention support device isdeveloped. By theoretical analysis and experimental research, the setting force and thebuffer absorption effect of the device are studied. The coupling support of flexible bodyand strong support is used for roadway of25110working face in Yuejin coal mine. Theimpact failure of traditional and rockburst prevention support is analyzed comparatively. The results primarily validate the reliability of rigid-flexible coupling rockburstprevention support.1. Absorbing mechanism study on porous metal materials and rockburst preventionsupport. With quasi-static compression experiment, high-speed impact experiment andSHPB experiment methods, the performance on dynamic mechanical properties andenergy absorption influenced by material parameters and microscopic structure changeis studied combined with two aspects of microscopic structure and macroscopicmechanical, and the energy absorption mechanism is revealed.(1) Study on the influence of dynamic mechanical properties of different foammetalsBased on impact test and scanning electron microscope(SEM) technology,combined with two aspects of microscopic structure and macroscopic mechanical, thestress-strain and absorbing energy curves of closed-cell foam metals with matrix Al,matrix Al-Si6, matrix Al-Si12, Mg matrix, aluminum-fiber and RE-Al alloys arediscussed, and then optimize the good performance of porous metal materials of energyabsorption.(2) Analysis on the dynamic mechanical properties of porous metal materialsinfluenced by material properties.With high-speed impact experiment and SHPB experiment research methods,considering material parameters on the influence of absorbing energy performance, therelationship between dynamic mechanical characteristics and density, porosity and poresize are studied. Accordingly, the suitable material parameters are determined.(3) Analysis on dynamic mechanical properties of porous metal materials with theconsideration of the size effectSample shape and size effect on its dynamic mechanical characteristics arediscussed with impact load experiment system, choosing closed-cell foam metals withmatrix Al-Si6. Then the rational height-width ratio is confirmed.(4) Absorbing mechanism research on porous metal materials and rockburstprevention supportBy scanning electron microscope(SEM) technology, mesoscopic fracturemorphology of closed-cell foam metals with matrix Al, matrix Al-Si6, matrix Al-Si12, Mg matrix, aluminum-fiber and RE-Al alloys are studied. Using impact load experimentsystem, energy absorption performance of rockburst prevention support is analyzed.Accordingly, energy absorption mechanism is revealed.2. Analysis on rigid-flexible coupling model and rockburst prevention theory. Fromthe angle of energy absorption, the stress criterion and energy conditions of surroundingrock in rockburst roadway are theoretically analyzed, and rigid-flexible coupling modeis established; the theory of rockburst prevention support is studied; and thenrigid-flexible-rigid coupling support method is put forward.(1) From the angle of energy absorption, the failure mechanism of surrounding rockis studied; the stress criterion and energy conditions of surrounding rock in rockburstroadway are theoretically analyzed.(2) Based on the impact destruction theory of stress wave, rigid-flexible couplingenergy absorption supporting mechanics model of rock-energy absorption material-steelis established, the coupling relationship of rigid-flexible coupling energy absorptionsupporting is revealed, and shock wave dissipation mechanism and energy dissipationmechanism are studied, too. The energy dissipation standards for rockburst preventionsupport are revealed.(3) According to the material mechanics and relevant knowledge to shockwavetheory, attenuation shockwave performance of R-F-R supporting structure undershockwave effect is theoretically analyzed. The influence of porous metal materialthickness and material properties on the attenuation shock wave is received. At last,energy absorption effect of rockburst prevention support is studied.(4) In order to reduce the impact type hydraulic disaster effectively, rigid-flexiblecoupling support patterns are put forward, the coupling support of flexible body+strongsupport is established.3. Experimental research on impact roadway. Under explosive loading and thedigital speckle correlation method(DSCM), the dynamic failure process of roadwayunder high velocity impact loading is simulated by using similarity simulationexperiment. Then the impact damage process of coal roadway under anchor bolt, U typesteel and rigid-flexible coupling support is studied. The impact failure mechanism ofroadway under the interaction between coal rock and support is revealed. (1) Adopting similarity simulation experiment under explosive loading and thedigital speckle correlation method(DSCM), the dynamic failure process of roadway ofanchor bolt and rigid-flexible coupling support under high velocity impact loading issimulated.(2) Utilizing similarity theory, adopting uniaxial loading method and digitalspeckle measuring methods, material blending ratio and strength for rockburst is definedby compression test.(3) Considering the influence of size effect, experimental research on deformationlaw of roadway under high-speed impact load, and the roadway damage degree underdifferent supporting conditions, the reasonable and effective in roadway support isverified.4. Using nonlinear dynamic analysis method，the law of deep roadway deformation underhigh-speed impact loading is analyzed by FLAC3Dcalculation software. The impact damageprocess of coal roadway under anchor bolt, U type steel and rockburst prevention support arestudied. The supporting effect of different support types is analyzed from the angle of energy.All the above shows the effectiveness of the rockburst prevention support further.5. According to the design basis of rockburst prevention structure, the rockburst preventionsupport device is developed. By the combination methods of theoretical analysis andexperimental research, the setting force and the buffer absorption effect of rockburst preventionsupport device are studied. The reasonable angle of eliminate self-locking and the relationshipbetween the spring compression value and the setting force are obtained. The results furthershow the reliability of rigid-flexible coupling rockburst prevention support. And then theresearch results can offer scientific basis for the supporting design and it’s application.6. Based on the rigid-flexible coupling rockburst prevention mechanism, the couplingsupport of flexible body+strong support is used for roadway of25110working face in Yuejincoal mine. The impact failure of traditional and rockburst prevention support is comparativelyanalyzed. The results primarily validate the reliability of rigid-flexible coupling rockburstprevention support.