Viscoelasticity and yield behavior of loess mudflows: experimental insights under varied density and temperature conditions

Loess, as a typical non-Newtonian fluid, exhibits complex rheological behavior under stress, which is of fundamental importance for predicting geological hazards, guiding soil-water conservation practices, and optimizing agricultural management in loess regions. This study systematically examines the coupled effects of bulk density and temperature on the rheological properties of loess sourced from Yan’an and Baoji, China, using a rotational rheometer. Through amplitude-sweep and shear-rate-sweep tests, the viscoelastic response, shear-thinning behavior, and yield characteristics are characterized. Results show that loess displays pronounced shear-thinning, with apparent viscosity decreasing markedly as shear rate increases, especially within the low shear-rate regime. Both density and temperature exert strong control over key rheological parameters: higher density and lower temperature significantly enhance yield stress, consistency coefficient, and the extent of shear-thinning. The Herschel–Bulkley model provides an excellent fit for flow curves at shear rates ≥5 s -1 . Moreover, viscoelastic indicators such as storage modulus and loss factor vary distinctly with density, reflecting intrinsic differences in micro-structure and particle interactions between the two loess types. The findings advance the mechanistic understanding of loess flow and offer a quantitative basis for assessing landslide initiation, designing soil-stability measures, and improving irrigation and tillage strategies in sensitive loess landscapes.