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Abstract To investigate the deformation behavior，strength and damage properties of rock salt subjected to cyclic loading under confining pressure condition，a series of triaxial cyclic loading/unloading tests were conducted for rock salt specimens with different loading waveforms(maximum and minimum stress，stress amplitude and loading frequency) and confining pressures utilizing TAW–2000 computer-servo rock triaxial testing machine. A two-stage(primary and steady) evolution law of axial cumulative strain was obtained through test. The irreversible deformation and the steady deformation rate will be accelerated through increasing maximum applied stress，stress amplitude，or reducing minimum stress，confining pressure，and loading frequency. The effects of maximum stress and stress amplitude on the deformation development and the damage degradation are more remarkable compared to other influencing factors. The Young?s modulus of the rock salt decreases with loading cycles as an exponential function and drives to a constant after 50–100 cycles. Whether the secondary compression strength of rock salt increases or not，depends mainly on the damage caused by the applied stress level of cyclic loading. The threshold value of maximum stress for rock salt under triaxial cyclic loading is indirectly deduced among 80%–89% based on experimental results.
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Received: 29 October 2012
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2013, Vol. 32 
