Study on creep characteristics and constitutive model of peridotite

In order to research the creep mechanical property of peridotite which was taken from the Anding Tunnel of the Yumo Line of the China-Laos Railway, creep test under different confining pressures and conventional compression test were carried out. The test results show that the ratio of the elastic modulus of saturated peridotite specimens to that of dry specimens is close to the softening coefficient peridotite. Meanwhile, the Poisson’s ratio of the saturated peridotite specimens is slightly larger than that of the dry specimens. The instantaneous strain produced after peridotite loading is mainly elastic strain, and peridotite has a creep initiation threshold. When the axial deviatoric stress is lower than the creep initiation threshold, the peridotite only has instantaneous strain without creep strain. Only if the axial deviatoric stress is larger than the creep initiation threshold, creep phenomenon occurs in peridotite. As the surrounding rock pressure increases, the creep initiation threshold and accelerated creep threshold of peridotite have a linear increasing trend. Based on the creep mechanical property of peridotite above, a creeping model of 7-element nonlinear viscoelastic-plastic was established to describe the creep behavior of peridotite. At the same time, the rationality of the model was verified by the creep test results. The results show that the established model can better reflect the creep mechanical behavior of this kind of rock. © 2022 Academia Sinica. All rights reserved.