Abstract: Uniaxial cyclic loading/unloading experiments were conducted on dry and saturated sandstones from Xiaojihan coal mine in Shaanxi province to study the deformation and strength characteristics， acoustic emission (AE) and load/unload response ration (LURR) in the failure process of sandstones. The results show that water has a significant influence on the properties mentioned above. The compressive strength and plastic hysteresis loops number of water-saturated specimens are less than that of dry specimens， and the axial strain in the compaction stage of water-saturated specimens is 18.9% larger than that of dry specimens， but the axial strain prior to peak strength of water-saturated specimens is 17.4% less than that of dry specimens. The elastic moduli of dry and saturated specimens both tend to increase during the cyclic loading/unloading process. AE cumulative energy of dry and saturated specimens is 3.87×10^-11J and 2.58×10^-11J respectively， and the latter is reduced by 33.3%. Furthermore， the LURR of dry and saturated specimens shows similar changing laws， but the characteristic peak time of saturated specimens appears earlier， which means the macroscopic crack generates earlier in saturated specimens.

Key words: uniaxial compression, cyclic loading/unloading, saturated rock, acoustic emission, load/unload response ration