Non-stationary Burgers model for rock

A nonlinear viscous component whose viscous coefficient is nonlinear function of stress and time was built.This nonlinear viscous component could describe nonlinear viscous property of rock.The viscous components of Burgers model were replaced by this nonlinear viscous component,thus,modified Burgers model was obtained.The modified Burgers model was also called as non-stationary Burgers model.The comparison between Burgers model and non-stationary Burgers model was carried out by using the biaxial compression creep tests data of green schist from auxiliary tunnel at Jinping Second Stage Hydropower Station.The research results show that non-stationary Burgers model curve and experimental curve approximately coinside with each other,and the accuracy of fitting is higher than that by using Burgers model.Therefore,non-stationary burgers model is available and reasonable.