Dynamic response and meso-deterioration mechanism of water-saturated sandstone under different porosities

Abstract

The dynamic response of sandstone to porosity and the amount of water are crucial to understanding the role of these physical parameters on the dynamic behaviour of rock. This study used four different types of sandstone, selected based on a microscopic analysis, for experimental tests and an analytical evaluation. During the experimental tests, dynamic compressive examination was employed on these types of sandstone under both water-saturated and dry states. The ratio of dynamic mechanical parameters of water-saturated sandstone to those of dry sandstone was focused on to eliminate the effect of the self-properties of the sandstone. The results indicate that the effect of water saturation on the dynamic mechanical properties of sandstone significantly affected by the porosity and the weakening degree of water saturation to sandstone positively correlates with the porosity. This effect is intuitively expressed in the features of the fracture propagation as recorded by a high-speed camera and dominated by the micromechanics between the pores and microfracture. This is microscopically attributed to the effect of the pore water pressure and the Stefan effect between the fracture surface and water on the fracture initiation and propagation. In addition, the dynamic mechanical model was further established and applied to discuss the effect mechanism of porosity on the dynamic behaviour of water-saturated sandstone. These insights can contribute significantly to improving the safety and cost-effectiveness of water-saturated rock engineering.