Research On Nonlinear Dynamic Stability Of Strip Mining Engineering

The mechanical system consisted by the strip coal pillar and roof was constantly changedwith external conditions in some factors.Under the condition of external disturbance, strip miningrock equilibrium state or state of motion would occur suddenly changed, it was very necessary forthe dynamic system stability analysis.First, the mining subsidence sensitivity was analysed becauseof the changing of engineering physical mechanical parameters of rock and mining geometry in thearticle, the key factor of surface subsidence were found out.The roof was looked as the border fixedelastic rectangular plate, the approximate equivalent of strip coal pillar for a continuous distributionof Weibull elastic foundation, the viscoelastic model differential equations were derivated under therectangular plate on viscoelastic foundation by Winkler elastic foundation and the rheological theoryof dynamic load, the equation solution were discussed respectively under the presence of theundamped case and damping. Taking the case of small damping as example, the effect of parameterswas analysed on strip mining engineering mechanics system, focusing on the damping, stiffness,thickness of roof, recovery rate and external load frequency change on system stabilitycharacteristics influence, it was put forward by adjusting the stiffness of the system and the geometryof the structure as well as mechanical state to control system of strip mining engineering instability,specific measures were put forward.Then, it was established in the static load and dynamic load under the combined action of stripcoal pillar system nonlinear dynamics model, according to the double cusp model of catastrophetheory, the strip coal pillar self vibration frequency was changed with the static load variation. Themutated instability of necessary and sufficient conditions with coal pillar was derivated. Because ofthe function of the coal pillar nonlinear adjustment coefficient, system frequency and amplitude wasplayed an important role in the strip coal pillar stability in the dynamic disturbance.The strip coalpillar stiffness, damping force, recovery ratio and elastic modulus and the system nonlinear dynamicinstability region of rats were studied. When external disturbance frequency was in a certain range ofthe system natural frequency, the tiny change on the system steady state plays a significant change.Then，the coal pillar dynamic differential equation was changed into Duffing equation, the resultsshow that the existence of chaos movement may appear under cyclic loading through the numericalsimulation, chaotic motion must be analysed. Finally, combined with the strip mining experience ofFengfeng area and Wannian mining under buildings actual condition,,Zhuang Yan village under the pressure of coal strip mining scheme was identified after a comprehensive analysis,and on basis ofthe above, the FLAC3Dnumerical model was established, the seismic waves on the strip mining ofrock stability influence was analyzed using the dynamic time-history analysis method. Accordingto Mohr-Coulomb with tensile constitutive relation, the stability of strip coal pillar unit was judgedusing yield strength criterion. The unit safety coefficient of the strip coal pillar was gotten. The stripcoal pillar stability would be reduced after earthquake, so the exploitation of design must beconsidered in the process of dynamic load effect.The reasearch would be provided with the important theory and the practical significance onstrip mining technology in three-underground mining application and development, covering therecovery rate of coal resources improved, the protection of surface buildings and ecologicalenvironment, the sustainable development of the coal industry realized.