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STUDY ON PHENOMENON OF SELF-WEAKENING OF STRAIN HARDENING OF SALT ROCK |
| CHEN Jie1，2，FAN Jinyang1，JIANG Deyi1，WU Jianxun1，LIU Jianxing1 |
| (1. State Key Laboratory for Coal Mine Disaster Dynamics and Controls，Chongqing University，Chongqing 400044，China；2. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China) |
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Abstract In order to explore the mechanisms that govern the self-weakening of strain hardening of salt rock，the tests under uniaxial compression unloading，standing still and second time loading were performed with the variation of indices of strength and strain obtained in this study. The micro-mechanism of the phenomenon of self-weakening of strain hardening was explained with the dislocation theory. After self-weakening，the peak strength and elastic modulus of rock salt in the second loading period exhibited a weakening trend with the interval time between two times loading tests. When the interval time was less than 4 h，the strength indices decreased sharply. While for the case of more than 4 h，no evident decrease was observed. When the interval time was approximately 4 h，Poisson?s ratio and isometric deformation rate of salt rock jumped upward and downward. The self-weakening effect was resulted from the behavior of crystal dislocations that was removed away from original dislocation accumulation zone due to the drive of residual stress(mainly friction and unevenly elastic dislocation force).
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2015, Vol. 34 
