The effect of water on the creep behavior of red sandstone

Abstract

Water is an important factor influencing the long-term stability of underground construction. In the present work, a series of uniaxial compressive strength tests and multistage creep tests were performed on red sandstone specimens under different water soaking conditions. The results show that the peak strength and elastic modulus of the red sandstone decrease with not only water content but also immersion time, which can be better expressed by a negative exponential function. Multistage compression creep tests were carried out on specimens immersed in water by using a self-developed “environmental chamber”. Based on the analysis of the test data, the creep properties of the red sandstone under different water soaking conditions were studied. Compared with the dry and saturated specimens without immersion in water, the soaking specimens exhibited significant increases in both the creep strain and the creep strain rate, while their time-to-failure and threshold stress for creep failure are much lower due to the long-term effect of immersion. Creep is accompanied by crack formation; water seeps into the newly created crack tips during creep testing, promoting crack propagation, increasing rock damage and accelerating rock failure process. The presented experimental results can provide a reference for estimating the long-term stability and safety of rock engineering.