Shear Creep Properties of Weak Interlayer in Slope Based on Stationary Parameter Fractional Derivative Burgers Model

Abstract

Based on special engineering geological conditions of a cut-slope area at Heitanping hilly-pass along Yongzhou-Jishou highway, shear creep properties of weak interlayer in this slope (about 30 m deep) have been studied by shear creep test to obtain shear creep curves. Shear creep constitutive model can be obtained by stationary parameter fractional derivative Burgers model, and long-term shear strength of the weak interlayer can be determined after the analysis of the shear creep curves. The research results show that the shear creep curves under different shear stresses have the same change tendency, which can be divided into three stages: instantaneous elastic stage, primary creep stage, and stationary creep stage, where both the instantaneous elastic deformation and primary creep time are increasing with the shear stress. On the basis of the shear creep constitutive equation, stress-strain isochrones of the soil have been constructed to identify the relationship between shear modulus G and time t. After the combination of deformation of the short-term shear strength and the G-t relationship, long-term shear strengths in different lengths of time have been obtained, which results in difference from the short-term shear strength. So the long-term shear strength should draw much attention to provide important theoretical references for the slope safety assessment.