Creep constitutive model of rock based on strength time-dependent characteristics

Abstract

The long-term stability and safety of supporting rock mass engineering has become the focus of rock mechanics research due to the continuous mining of deep resources. The single-specimen method was used to determine the mechanical parameters of undamaged specimens subjected to creep for 10, 60, and 100 h under different stress levels. The time-dependent model of mechanical parameters is established by analyzing the change law of mechanical parameters under the influence of stress and time. Results show that the decrease in the internal friction angle of rock is substantially less than that of cohesion under the influence of overstress difference and time, and the decrease in internal friction angle has minimal effect on the long-term stability of the rock. Therefore, cohesion should be considered in the long-term stability design when the roadway surrounding rock is devised in practice. The established strength parameter model can describe the variation of rock strength parameters under different stress states and time effects. The strength model also reflects the essential characteristics of varying rock strength parameters with stress and time. Meanwhile, the experimental curves are in good agreement with the theoretical ones. Therefore, the creep model based on the degradation of strength parameters established in this paper can reflect the creep characteristics of the rock at different stages. This model can also describe the accelerated creep characteristics of sandstone under high-stress state. Therefore, the rock creep model developed in this paper is reasonable and feasible for describing the creep properties under different stress states.