By means of stepwise incremental cycling loading and unloading

the experiment was done on uniaxial creep properties of siltstone at the floor of coal seam II in east roadway beneath300 mof Shuijingtou coalmine of Niumasi Mining Company of Hunan Xiangmei Group.The properties of the axial creep deformation and the nonlinear elastovisco-plastic deformation characteristics of siltstone in each creep stage were discussed.The test results show that the attenuation creep occurs when the stress level is lower than the long-term strength of siltstone.The instantaneous plastic strain and visto-plastic strain increase with the growth of axial stress.The instantaneous elastic modulus increases with the growth of stress level

while deformation modulus decrease gradually with the increase of stress level and time until it tends to be a certain stable value.With the increase of stress level

visco-elastic strain

visco-plastic strain and the total creep all decrease firstly and then increase.This phenomenon indicates that strain hardening forms because of the continous compaction of microcrack inside the rock under low stress

and strain softening occurs because of the constant degradation of the material properties of the rock under high stress.