With the slopes of an open-pit mine in Inner Mongolia as the research background, the creep characteristics of soft rock in the slopes were investigated by means of field monitoring, laboratory test and theoretical analysis. Real-time monitoring results of the slopes from radar and GNSS found that the creep deformation is relatively larger on the eastern side of the northern slope, which requires key protection. When the axial stress exceeds the long-term strength, the soft rock goes through four deformation stages:instantaneous deformation, decelerating creep, steady-state creep and accelerated creep. Creep deformation and creep rate of soft rock are positively correlated with axial stress. A nonlinear creep model for slope soft rock is established by combining elastic elements, fractional-order element and nonlinear viscoplastic body (NVPB). This model can well describe the whole creep process of slope soft rock, with higher fitting accuracy than that of traditional Burgers model, and also demonstrate favorable applicability.

open-pit slope  /  slope stability  /  slope soft rock  /  radar monitoring  /  nonlinear viscoplastic body  /  creep characteristic  /  creep model  /  fractional-order calculus