RESEARCH ON THE DEFORMATION CHARACTERISTICS OF SANDSTONE UNDER CYCLIC LOADING AND DIFFERENT SATURATIONS

The deformation characteristics of sandstore is studied under cyclic loading and four different saturations(drying,natural,undernourished,saturation state).As as results,the sandstore has typical elasticity-plasticity deformation characteristics;The deformation characteristics of sandstore increase,subdued intensity decline and compression strength decline with increasing of saturation exponent.The Upper limit-stress of the load-range diminish gradually.The slope of the hysteresis curve become taper,i.e.at the same load-range,The increment of the epaxial-deformation increase.The diametral-deformation and vol.-deformation largen.Vol.-deformation due to the epaxial-deformation and the diametral-deformation,but the diametral-deformation has great influence on it.The hysteresis curve would diminish but don't disappear and become more and more invariable.