Experimental and theoretical study on the compression characteristics of dry/water-saturated sandstone under different deformation rates

Mechanical and acoustic emission (AE) characteristics of dry and water-saturated sandstone under different compression rates were analysed, respectively. Based on the deformation rate enhancing and the moisture softening factors of rock's elasticity modulus, a one-dimensional constitutive model was proposed and validated by experimental results. Results show that the stress-strain curve of dry sandstone consists of three stages: elasticity, weak plasticity and fracture. Water-saturated sandstone has a relatively long compaction stage, a short elasticity stage and an extended plasticity stage. The compressive strength and elasticity modulus increase as the deformation rate is increased. The strength of water-saturated sandstone is lower than that of dry sandstone, and the difference of rock strength in the two states decreases as increasing deformation rate is increased. The elasticity modulus of water-saturated sandstone is lower than that of dry sandstone. The peak strain of sandstone is not sensitive to the deformation rate, and the peak strain of water-saturated sandstone is 32% higher than that of dry sandstone. The AE energy accumulation increases with the increasing deformation rate, and the energy accumulation of water-saturated sandstone is three to five times that of dry sandstone. The proposed one-dimensional constitutive model can describe the deformation characteristics of dry and water-saturated sandstone under different compression rates.