To investigate the creep characteristics of loess

we conducted consolidation–drainage triaxial creep tests on undisturbed Malan loess at different moisture contents

while monitoring axial

radial

and volumetric deformations throughout. The test results show that the creep deformation of Malan loess with different moisture contents is characterized by axial compression

radial expansion

volume compression

and then axial accelerated compression

radial accelerated expansion

and volume accelerated compression to damage. Based on the mechanical response and microstructural evolution of loess under creep

we conclude that creep macroscopically reduces loess strength and increases deformation

while microscopically causing structural damage to the soil. The mechanism involves three synergistic effects—water-induced reduction of interparticle resistance

load-induced space release

and time-dependent processes—that promote creep-slip of soil particles. Based on memory-dependent derivatives and damage mechanics

we propose a creep-damage constitutive model. The applicability of the new model has been verified by fitting the theoretical model to the creep test data. These results deepen our understanding of loess creep and have practical value for the long-term safety assessment of loess engineering.