Study on creep behavior and long-term strength of argillaceous siltstone under high stresses

Creep behavior of rocks under high stresses is one of the hot issues in the study of deep buried chamber stability. To study creep characteristics and long-term strength of argillaceous siltstone under high stresses, triaxial compression rheological tests were carried out on argillaceous siltstone specimens under graded incremental loading. The experiment results show that the creep of argillaceous siltstone has viscoelastic characteristics under low stressesand elastoviscoplastic characteristics under high stresses. Based on separating instantaneous elastic strain, viscoelastic creep and viscoplastic creep from the total creep of argillaceous siltstone under high stresses, the functional relationship between the steady viscoplastic creep rate and the stress was established. It is suggested that the threshold stress corresponding to the steady-state viscoplastic creep rate can be regarded as the long-term strength of argillaceous siltstone under high stresses. It is also shown that the long-term strength of argillaceous siltstones under high stresses, determined by the developed function between the steady viscoplastic creep rate and the stress, is 70.5% of the uniaxial compressive strength. The research provides a reasonable method for determining the long-term strength of rocks under high stresses. © 2020, Science Press. All right reserved.