Abstract
Abstract To study the dynamic damage and fracture of metamorphic limestone under explosive load and the stability of the surrounding rock, the stress-strain curve, fracture morphology, and energy dissipation characteristics of metamorphic limestone in the Dahongshan mining area under different strain rates were studied by the Hopkinson pressure bar (SHPB), stress wave analysis, and fractal theory. The experimental results show that the crushing form and degree are significantly affected by the loading strain rate. There are several typical failure modes. When the strain rate is 17.56 s−1, there is no obvious failure except corner cracks. When the strain rate is between 26.92 s−1 and 56.18 s−1, the failure mode of the specimen is axial splitting failure, and when the strain rate is 67.34 s−1, splitting and shearing failure occur. With the increase of the strain rate, the growth rate of the dynamic compressive strength slows down. Compared with static compressive strength, the strength factor increases from 1.15 to 4.19. Also, the fractal dimension shows a gentle increase. When Df is in the range of 1.82~2.24, there is a sudden change in fragmentation when the strain rate is in the range of 34.70 s−1~56.18 s−1. Energy dissipation density increases logarithmically with the strain rate. The results reveal the dynamic breaking and energy consumption laws of metamorphic limestone under impact loads with different strain rates and could provide some reference value for the safe and efficient construction in the Dahongshan mining area and similar engineering projects.
Highlights
During the engineering activity of tunnel excavation, mining, water conservancy, and hydropower station construction, the involving blasting and mechanical vibration have a great impact on the behavior of the surrounding rock mass
Zhang et al [23,24,25,26,27,28,29] carried out Split Hopkinson pressure bar (SHPB) tests on sandstone under different impact conditions and obtained stress-strain curves and rock fragmentation, and the peak strain, particle size distribution, and energy dissipation of sandstone were further analyzed
In order to express the strength of the energy dissipation of the rock sample under different strain rates, the ratio of the dissipated energy to the incident energy is introduced as the energy dissipation rate η, namely, Lithosphere
Summary
During the engineering activity of tunnel excavation, mining, water conservancy, and hydropower station construction, the involving blasting and mechanical vibration have a great impact on the behavior of the surrounding rock mass. Ma et al [11,12,13] conducted dynamic impact tests on artificially frozen sand and shale under active confining pressure, and the changes of stress-strain curves and strength parameters with confining pressure and strain rate were studied. Zhang et al [23,24,25,26,27,28,29] carried out SHPB tests on sandstone under different impact conditions and obtained stress-strain curves and rock fragmentation, and the peak strain, particle size distribution, and energy dissipation of sandstone were further analyzed. Analysis of the particle size distribution law and strength parameters, fractal dimension, and energy dissipation change law with the strain rate of specimens provides a certain scientific basis for safe and efficient mining of ore in the Dahongshan mining area
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