The weakening of rock mass after immersion substantially affects slope stability. Considering the mudstone in the north slope of the Fushun West Open pit as the research object, we investigated the failure and creep characteristics of mudstone under different immersion times and confining pressures. For this, we used a self-developed experimental apparatus that applies biaxial compression loading in a water immersion environment. Water significantly changed the strength and failure mode of the mudstone. The increase in confining pressure limits the expansion of the crack aperture, reduces the rock strength-weakening coefficient, and delays the rock weakening time. The change in cohesion is primarily responsible for the weakening of shear strength during immersion. Based on the creep test results, the creep curve of the soaking specimen was identical to that of the dry specimen in the initial phase. The weakening effect of water on the specimen increased as the soaking duration increased, due to which the creep curve of the soaking specimen gradually approached that of the saturated specimen. Water entered the microcracks and reacted with the rock interior, accelerating rock failure. Consequently, the soaking specimen had the lowest stress level for creep failure and the shortest failure time. The results of this experiment provide a reference for the long-term stability of the flooded slope.

This paper presents the experimental results of calcium argillaceous cemented sandstones with different water contents under uniaxial and cyclic loading conditions. The effects of the water content status on peak strength, deformation, and dissipated energy are discussed. Meanwhile, the acoustic emission energy is also studied based on the accelerating energy release theory and energy distribution density function. The experimental results show that the water content has remarkable effects on the peak strength and elastic modulus by a decrease of 37–58% and 15.7–21% after being saturated, respectively. Both the accumulated dissipated energy and dissipated energy generating ratio of dry specimens are higher than those of the saturated specimens. The acoustic emission energy release rate of dry specimens is higher than those of the saturated specimens, which means a high tendency of sudden failure for dry specimens. Moreover, the distributions of acoustic emission absolute energy are consistent with the normal density distribution function, and the AE energy expectations of dry specimens are higher than those of the saturated ones in the loading process and they show an obvious increasing trend on approaching failure. These conclusions will be helpful for the illumination of water-weakening effects on the mechanics parameters and failure mechanism analysis in view of the releasing energy.