Creep mechanical properties and creep model of high water material under step loading

Abstract

AbstractHigh water material, a kind of filling and supporting material, is widely used in underground engineering, whose creep mechanical properties are directly related to the underground engineering stability. In this paper, creep tests of different types of high water material are carried out. The results show that: for the complete specimen and the single and double crack specimens with crack inclination angles of 0°, 30°, and 60°, the curves present initial elastic, creep attenuation and creep stabilization in the first four stages, and the creep acceleration appears in the fifth stage, leading to the final failure of the specimen; for the single and double crack specimens with a crack inclination angle of 90°, no creep acceleration appears. According to the test results, a new nonlinear viscoplastic body is proposed, and connected with the traditional Nishihara model, forming the nonlinear Nishihara model. The new model can clearly describe the creep characteristics of complete and cracked specimens at different stages. Finally, according to the new creep model, crack parameters are discussed with the creep rate index and the starting time of accelerated failure.