Study On Mechanical Properties Of Limestone Under One - Dimensional Dynamic And Static Combined Load

Rock burst usually occurs in underground works which is subjected to high stress, such as tunnels or underground mining chamber excavation, so rock burst become a very serious engineering disaster, which is taken more and more attention in international field. For the reason, by combining the test was conducted by a modified triaxial split Hopkinson Pressure Bar (SHPB) in Central South University and numerical methods with Flac3D, the article studies mechanical properties of rock under dynamic impact to show the "high stress+dynamic disturbance" force mode in deep rock. Lastly, the results provide a reference for the study of the nature of rock burst.Experimental research shows that:1)When dolomite was not damaged seriously under impact loads.the stress-strain curves in the late peak generally showed a characteristic phenomenon called "strain back"; while when dolomite was damaged, it showed a trend curve similar to static load test.the former phenomenon would not appear.2)Under conditions of similar strain rate, rock dynamic strength will increase first and then decrease with the increase of axial compression; When the axial pressure reaches someone that is56%to71%of rock static loading, the dynamic bearing capacity of rock began to decrease:rock dynamic strength will increase with the increase of strain rate.3) In the absence of confining pressure, the rock showed energy absorption state after impacted, while, under axial compression condition rock samples are presented releasing energy state:axial pressure increases, the energy absorbed by the rock gradually reduced until began to present releasing energy.Numerical simulation results show that the:1)With increasing axial pressure, axial stress in the rock caused by dynamic load gradually decreased, and displacement increased; with dynamic load increasing, axial stress in the rock caused by dynamic load gradually increased, the displacement increased; With increasing frequency of dynamic load, axial stress basically unchanged, but the displacement decreases.2) Axial static and dynamic load determines the axial stress distribution of the rock, frequency of dynamic load make little effect:The dynamic load amplitude and frequency of the dynamic load of rock is the main influencing factors of internal displacement, and axial static pressure make little effect.3) Through internal real time monitoring of rock, it showed that the axial displacement of the rock reached the peak and then reduced, which is consistent with the" strain spring back "phenomenon.In this paper, combining indoor static loading experiment and numerical simulation of one-dimensional coupled static and dynamic loads, the rock mechanics characteristics are analyzed, the results can provide experimental basis and reference for deep mine rockburst mechanism and prediction.