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Abstract The uniaxial compression cyclic loading and unloading tests on fine sandstone comes from the foundation rock of a nuclear power station are carried out on the MTS 815 Flex Test GT rock mechanics test system. The longitudinal and transverse deformation characteristics of fine sandstone are studied under cyclic loading；and the effects of cyclic loading numbers and dynamic stress amplitudes on dynamic elastic modulus，dynamic Poisson?s ratios，damping ratios and damping coefficients are discussed. The results indicate that the longitudinal strain is larger than the transverse strain for the same stress. With the cyclic numbers increasing，the increment of longitudinal strain is larger than that of transverse strain under low amplitude stress；but it is reverse under high amplitude stress. The changing characteristics of stress-strain curves for the unloading process of transverse strain hysteresis loops and the loading and unloading processes of longitudinal strain hysteresis loops are all outstanding down，while the changing characteristics of loading process for transverse strain hysteretic loops are reverse. With the dynamic stress amplitude increasing，dynamic elastic modulus and dynamic Poisson?s ratio increase on a parabola and linearly，respectively，while the damping ratios and damping coefficients decrease by power function law. The damping parameters gained by the sixteenth hysteresis loops can completely denote the damping characteristic of the testing rock. With the cyclic numbers increasing，damping ratio and damping coefficient both increase linearly；and the increment under low amplitude stress is larger than that under high amplitude stress.
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Received: 01 July 2011
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2012, Vol. 31 
