The values of rock dynamic parameters directly influence the results of dynamic calculation in rock structural engineering

which shall be validated with the results obtained from practical engineering projects. As the frequency and amplitude of actual dynamic loading could change within a specific range

a series of cyclic loading and unloading experiments was conducted by considering the variations of these two factors. The effects of these two factors on the dynamic characteristics of sandstone were analysed

such as dynamic stress-strain hysteresis curve

dynamic elastic modulus

damping ratio and damping coefficient. The results showed that the shape of stress-strain hysteresis loop was closely related to the frequency and amplitude of cyclic loading and unloading. It was found that the higher the frequency was

the plumper the hysteresis loop was

and the greater the cyclic loading amplitude was

and the narrower the hysteresis loop was. When the frequency of cyclic loading increased from 0.02 Hz to 1.00 Hz

the damping coefficient of sandstone gradually decreased

whereas the damping ratio and dynamic modulus slowly increased. The varying ranges of damping coefficient and damping ratio were relatively larger

while the growth range of dynamic elastic modulus was smaller. When the stress amplitude of cyclic loading increased from 10 MPa to 35 MPa

the damping ratio of sandstone gradually decreased

whereas the damping coefficient slightly changed and the dynamic elastic modulus slowly increased. However

the effects of stress magnitude on the dynamic elastic modulus were more significant. Therefore

this study can provide useful references for reasonably selecting dynamic parameters of rock mass.