Mechanical Analysis On Interaction Between Dynamic Disturbance-Relaxation Test Machine And Rock Specimen

In underground mining,it is generally existed that unloading relaxation of surrounding rock mass after tunnels excavation under static loading of original stress,and then it is disturbed frequently by mining blasting.Therefore,It is necessary to conduct laboratory test on mechanical properties of rock under static-dynamic coupled loading and clarify damage and instability process of relaxant rock mass under dynamic disturbance,which contributes to have a further understanding on support object,surrounding rock stability,and mechanical interaction between support and surrounding rock.This thesis researches on the mechanical interaction process between dynamic disturbance-relaxation test machine and rock specimen system,analyses the instability condition and energy release amount under static loading and static-dynamic coupled loading.In addition,establishes a numerical model of dynamic disturbance-relaxation test machine and rock specimen system,analyses the influence of test machine stiffness on rock specimen deformation.This thesis deals with the following issues:(1)Based on the dynamic disturbance-relaxation test machine and rock specimen system,establishes cusp catastrophe model and uniaxial compression instability condition of dynamic disturbance-relaxation test machine and rock specimen system under quasi static loading.(2)Based on the catastrophe theory,establishes the mathematical expression of instability criterion,jumping displacement,and total energy release amount of dynamic disturbance-relaxation test machine and rock specimen interaction system under static-dynamic coupled loading,analyses the influent factors on the instability of the interaction system.(3)Using ANSYS software to analyze mechanical response of test machine and rock specimen interaction system under static loading,and analyzes the deformation relationship between the test machine and different rock specimens.(4)Using ANSYS/LS-DYNA software implicit-explicit sequence analysis method to realize static-dynamic coupled loading,analyzes the deformation of test machine and rock specimen,monitor the variation tendency of particle displacement,stress and strain of the test machine and rock specimen interaction system.Based on catastrophe theory,the instability of dynamic disturbance-relaxation test machine and rock specimen interaction system under static loading condition is mainly determined by stiffness ratio,geometric properties and material parameters of system,and it is also determined by strain rate of rock specimens under static-dynamic coupled loading.In addition,the results of numerical analysis show that the stiffness of test machine is large enough to satisfy the soft rocks in dynamic disturbance-relaxation experiment.