Viscoelastic–plastic response of tunnels based on a novel damage creep constitutive model

Abstract

Geomaterial rheology plays an important role in engineering stability and can be used to understand the deformation behavior of rocks. This study proposes a novel damage constitutive model to describe the rheological properties of rocks, which includes a Maxwell body, a Kelvin body, and a new damage-plastic element. A series of uniaxial rock creep tests were performed, and the experimental results can verify the proposed viscoelastic–plastic model. A closed-form analytical solution of surrounding rock creep in a circular tunnel is derived using the proposed model, and parametric studies are examined to determine the influence of parameters on the surrounding rock deformation. Dengjiashan tunnel in Sichuan, China is employed to verify the analytical solution. The results show that the proposed viscoelastic–plastic model well describes the entire rock creep process. The geological strength index has a significant influence on the surrounding rock deformation. The analytical results agree well with the experimental and monitoring data. The proposed analytical solution can therefore be applied to predict the creep deformation of surrounding rocks due to tunnel excavation.