Study On The Stress State And Fracture Response Characteristics Of Granite Under Dynamic Load

Based on the research background of the change of dynamic stress state of dynamic load engineering such as mine step blasting,combined with the strain rate effect and dimensional effect of dynamic load rock crushing,this paper analyzes the two state change laws of stress balance and stress deterioration in the dynamic impact process of rock.Combined with theoretical analysis and dynamic testing,this paper analyzes the granite crushing process of different long diameter ratio under impact load,and studies the change of rock dynamic stress state and the response characteristics of crushing energy consumption in the specific strain rate range.（1）According to the results of the Split Hopkinson Pressure Bar test,the relative value of stress difference at both ends of the rock is calculated to determine the response time of different long diameters over granite dynamic stress equilibrium states.The results showed that,under the same impact load,the time of 0.6 to 1.4 long diameter than granite dynamic stress equilibrium was 30μs,72μs,20μs,24μs,and 0μs.Under the effect of 12 m/s impact velocity,a good stress equilibrium can be indicated when the granite length-diameter ratio is 0.8.（2）Based on the dynamic load rock size effect,comparing the changes of different long diameters over granite stress states,the results show that 0.6 to 1.0 long diameters are easier to achieve dynamic stress than granite under the same impact load.Equilibrium state;1.4 long diameter ratio granite in the stress pulse time,the relative value of stress difference at both ends of the rock is mostly 20%to 30%,granite in the state of stress deterioration to complete the dynamic load deformation process.（3）Based on the dynamic load rock strain rate effect,compared with the difference of dynamic stress equilibrium state under different load strain rate of granite.The results showed that when the 0.6 long diameter ratio granite load strain rate was reduced from 160.3 s^-1 to 109.8 s^-1,the response time of the dynamic stress equilibrium state increased significantly by 33μs,an increase of nearly 109%.（4）According to the dynamic stress equilibrium of the rock to show the obvious strain rate effect and dimensional effect,to determine the different long diameter than the rock there is a reasonable load strain range can achieve a good dynamic stress equilibrium state.The research shows that:0.6 to 1.0 long diameter than granite load strain rate at 90 s^-1 to 100 s^-1 can achieve a long-term stress balance state,for 1.2 to1.4 long diameter ratio granite,can appropriately improve the load strain rate to improve the dynamic stress balance action time is small problem.（5）Combined with the stress equilibrium action time and energy-time density index,it can be determined that rocks are suitable for different research directions in different load strain ranges.The research shows that 0.6 long diameter ratio granite,load strain rate range of 50 s^-1 to 100 s^-1,helps the rock to obtain more effective data on stress equilibrium state moment,suitable for studying the dynamic characteristics of rock;...