Abstract
In order to study the dynamic mechanical properties of the surrounding rock of roadway in deep mines with rock burst, cyclic impact compression tests of sandstone under different impact velocities were carried out by using the split Hopkinson pressure bar (SHPB) test system, and the dynamic stress-strain curves of the samples under cyclic impact loads and the relationship between energy dissipation and impact numbers were analyzed. The results show that, as the impact loading times increase, the initial elastic modulus of sandstone samples decreases, the peak stress decreases, and the peak strain increases; the average strain rate increases. The cumulative damage of sandstone samples under impact load is significantly affected by impact velocity and times. During the cyclic impact test, the reflected energy of sandstone increases with the increase of impact numbers, while the transmitted energy decreases and the absorbed energy increases; the cumulative specific energy absorption variable is introduced, and the cumulative specific energy absorption value of the samples increases with the increase of impact numbers, which can better characterize the variation of energy accumulation and dissipation of sandstone samples under cyclic impact.
Highlights
With the exhaustion of shall coal resources, more and more coal mines in China are turning to deep mining
The dynamic response of the coal and rock mass, the mining stress field, and the accumulation and release pattern of energy have all undergone significant changes. e experimental study on dynamic characteristics of instantaneous impact failure of underground rock mass provides an experimental basis for further understanding of the mechanism of rock burst and for the monitoring and early warning of dynamic disasters, which is of great significance to the production safety of coal mines
By considering the coupling effect of in situ stress and dynamic load of the rock mass in underground works, Jin et al [12] carried out 3D dynamic compression tests on red sandstone and analyzed the variation of its average strain rate, dynamic peak stress, ultimate strain, and dynamic deformation modulus under different impact velocities and static stress conditions
Summary
With the exhaustion of shall coal resources, more and more coal mines in China are turning to deep mining. By considering the coupling effect of in situ stress and dynamic load of the rock mass in underground works, Jin et al [12] carried out 3D dynamic compression tests on red sandstone and analyzed the variation of its average strain rate, dynamic peak stress, ultimate strain, and dynamic deformation modulus under different impact velocities and static stress conditions. Erefore, the study of the dynamic characteristics of sandstone under cyclic impact load is of great theoretical and practical significance for blast-induced cracking control and the stability of roadway surrounding rock [15]. Wang et al [21]and Luo et al [22] analyzed the dynamic failure process of sandstone under cyclic impact load through numerical calculation method and laboratory experiment, and the dynamic deterioration characteristics and evolution laws of mesocracks are studied from both mesoscopic cracks and energy point of views. Based on the stress-strain relationship, the dynamic mechanical properties and energy dissipation rules are analyzed. e research results are of certain significance for guiding actual project construction
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