Abstract
To investigate the coupling damage characteristics of rock after high-temperature treatment under impact load, dynamic uniaxial compression tests for deep sandstone specimen under laboratory conditions varying with high temperature (i.e., 25°C, 100°C, 300°C, 500°C, 700°C, and 900°C) and strain rate (i.e., 170 s-1, 205 s-1, and 240 s-1) were performed using splitting Hopkinson pressure bar (SHPB) system. Coupling damage variable of deep sandstone was deduced based on the Lemaitre equivalent strain theory. Moreover, the damage parameters of deep sandstone were systematically determined according to the test data, and the effects of high temperature and strain rate on damage growth curves were investigated. Finally, a dynamic compound damage constitutive model, which could consider the coupling damage, was established and verified to describe the dynamic mechanical characteristic of deep sandstone. Theoretical and experimental results indicated that the simulated stress-strain curves matched the test data well and the proposed coupling damage constitutive model could reflect the high temperature-induced weakening and strain rate strengthening effect.
Highlights
With the depletion of shallow resources in the earth, the proportion of deep resource mining is increasing gradually, and the effect of high temperature on the physical and mechanical properties of rock materials is becoming more and more prominent [1,2,3]
In addition to high temperature, deep rock structures are inevitably subject to impact loads derived from rock burst, blasting excavation, and earthquake [5,6,7]
It is of great practical importance to study the dynamic behavior of rock after different high-temperature treatments for rational design and rapid excavation in deep rock engineering
Summary
With the depletion of shallow resources in the earth, the proportion of deep resource mining is increasing gradually, and the effect of high temperature on the physical and mechanical properties of rock materials is becoming more and more prominent [1,2,3]. Research on damage characteristic and constitutive relationship of rock subjected to coupling high temperature and dynamic loads can help comprehend its dynamic behaviors and fracture process and improve stability analysis of underground excavation in deep rock engineering. By summarizing the experimental and numerical simulation achievements, it can be noticed that the previous works on mechanical characteristic of rock bearing coupling dynamic load and high temperature mainly give attention to strength and deformation characteristic, energy dissipation, and failure mode, while limited attempts have been made to study the damage characteristic and constitutive mode of deep rock considering the coupling thermal and dynamic damage. The defined method for the coupled damage variable considering both temperature and impact load is detailed in Section 3; the effects of strain rate and temperature on damage growth curves are investigated and discussed.
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