Visco-elastic–Plastic Creep Constitutive Relation of Tunnels in Soft Schist

To study visco-elastic–plastic creep constitutive relation of tunnels in soft schist, a triaxial creep mechanical test was conducted at first. Next, by studying linear and nonlinear visco-elastic–plastic creep constitutive relation of soft schist, the nonlinear visco-elastic–plastic creep constitutive model is established. The constitutive model can be used to describe the whole process of initial, steady and accelerated creep stages. By comparing the nonlinear visco-elastic–plastic creep constitutive model to a linear constitutive model, the characteristics of engineering applicability of different constitutive models are obtained. Finally, creep parameters, change law and influence law of moisture contents on the constitutive model are separately discussed, which provides practical and theoretical bases for analyzing long-term stability of surrounding rocks of tunnels in soft schist. © 2017, Springer International Publishing AG.