Research On Impact Mechanical Properties And Damage Law Of Ore-rock-filling Body

In recent years,as the mining depth of mines has increased year by year,the filling mining method has been widely used in large underground mines at home and abroad because of its safety,efficiency,and environmental protection.In the two-step stoping of the ore body,the drilling and blasting method is usually adopted.In the process of blasting and falling,the filling body adjacent to the ore rock and pillar is often disturbed by the impact load of the explosion.Under the disturbance of multiple blasting and excavation,the structure of the filling body is prone to fragmentation,collapse and other phenomena,which causes its strength and stability to decrease,thereby affecting the safe and efficient mining of the pillar.Therefore,research on the interaction mechanism and deformation evolution law under the coupling condition of ore rock and backfill has become a key issue for pillar mining.In order to study the dynamics of the combined medium of ore rock and backfill under shock loading conditions,this paper uses the?50mm Separate Hopkinson Experimental Device(SHPB)to conduct research on backfill,ore rock,and combined ore rock and backfill respectively.Uniaxial impact test.At the same time,a cyclic impact test was carried out on the ore-rock-filling body combination.Based on the measured data,the fluctuation characteristics,mechanical properties and mechanical characteristics of the single medium(ore rock,the filling body)and the combined medium under the impact load were respectively tested A specific analysis of the failure mode was carried out,and the following conclusions were drawn:(1)Carry out the SHPB impact test of the filling body,analyze the SHPB voltage waveform curve and find that the incident wave is mainly affected by the impact rate.The transmitted wave and the reflected wave are not only affected by the impact rate,but also related to the ratio of the filling body.;Comparing the stress-strain curves of fillings with different ratios,it is found that with the increase of the ratio,the mechanical properties of the fillings show a transition from brittle deformation to plastic deformation,in which peak stress and peak strain increase with the increase of strain rate It keeps increasing,but there is a certain difference in the trend of the two.There is a good linear growth relationship between the peak stress and the strain rate,and the relationship between the peak strain and the strain rate is an exponential function.Comparing the failure morphology of the filling body under different strain rate conditions,it can be seen that the failure morphology is combined with tensile failure and shear failure,which is affected by the strain rate and the ratio.(2)Carry out the SHPB impact test of copper-bearing ore and analyze the dynamic characteristics and failure laws of a single medium of copper-bearing ore.The peak stress and strain rate have a linear growth relationship,and the peak strain and strain rate have an exponential function relationship.When the strain rate increases from 30.7s^-1to 106s^-1,the peak stress increases from 65MPa to 102MPa,and the peak strain increases from 0.011 to 0.023.The failure mode of ore rock is closely related to the strain rate.With the increase of the strain rate,the broken pieces of ore rock develop from the coarse end to the fine end.(3)Carry out the SHPB impact test of the ore rock-filling body composite specimen,explore the dynamic characteristics and failure mode of the composite medium,analyze the change law of the fragmentation mass with the incident energy,and reveal the ratio of energy and crushing energy consumption.Relationship between.Through analysis,it is found that the composite specimen has a strong rate correlation.Within a certain range,its dynamic compressive strength and strain rate are positively correlated,and its failure mode is also affected by the strain rate.When the strain rate is small Under the circumstance of,there are sporadic debris on the edge of the end of the filling body part of the combined test piece.With the increase of the strain rate,the fragmentation of the filling body part becomes more severe.With the increase of incident energy and dissipated energy,the fragmentation of the filling part in the composite body is also increasing.The broken mass increases linearly with the incident energy,and there is a good ratio between the incident energy and the energy consumption of the fragments.The exponential relationship.(4)Carry out the SHPB cyclic impact test of ore-rock-filling body composite specimens,and analyze the four aspects of fluctuation characteristics,mechanical characteristics,energy ratio and damage accumulation.It is found that with the increase of the number of impacts,the reflection coefficient gradually increases,and the transmission coefficient gradually decreases.Under the same impact load condition,the 1:4 composite specimen has a larger transmission coefficient than the 1:6 composite specimen.The reflection coefficient is small.For composite specimens under cyclic impact load,the ratio,impact air pressure and number of impacts are all important factors that affect their mechanical properties.Under equal load cycle impact,the energy reflectivity is positively correlated with the number of impacts,and the dissipation is negatively correlated with the number of impacts.When the number of impacts is equal,the reflectivity is positively correlated with the impact air pressure,and the dissipation rate is negatively correlated with the impact air pressure.The composite test piece with a ratio of 1:4,the impact air pressure is 0.2MPa,after 5 cycles of equal load impact,the damage variable D(counting from the second time)is 0.07,0.11,0.51,0.56,respectively;The air pressure is0.24MPa.After 5 cycles of equal load impact,the damage variable D is 0.17,0.29,0.55,0.66,respectively.It is found that the damage variable growth rate is relatively small under the condition of lower air pressure.