Water-induced variations in dynamic behavior and failure characteristics of sandstone subjected to simulated geo-stress

In underground rock engineering, rock structures at great depth are commonly subjected to water infusion, static geo-stress as well as the dynamic disturbances. It is thus essential to understand the influence of water saturation on the dynamic behavior of rock under static pre-stress. In this paper, coupled static-dynamic loading tests were conducted on oven-dried and water-saturated sandstone specimens with 0–62.5 MPa axial pre-stresses. Test results show that, for each pre-stress, the dynamic strength of both dry and saturated specimens increases with the increase in strain rate. The rate dependence of saturated specimens is greater. Under a similar loading condition (i.e., same pre-stress and similar incident energy), compared with dry rocks, saturated ones possess lower dynamic strength, consume less energy before failure, dissipate more energy during post-peak stage, and produce a larger proportion of finer particles. Moreover, the comparison of failure patterns between dry and saturated specimens under different pre-stresses suggests that the critical energy of each failure pattern for saturated specimen is lower than that for dry ones. This would be responsible for the more frequent occurrence of many dynamic geo-hazards at depth under hydrated condition.