Study on the strength and deformation characteristics of loess under multi-staged unloading

Abstract

The strength and deformation characteristics of loess under vertical unloading path is important for the study of slope instability in excavation area. From the perspective of engineering application, direct shear test is carried out. Moreover, a discrete element method model is established to study micro-mechanism of multi-stage unloading. It is found that the shear displacement-shear stress curve of the soil under the multi-stage unloading path is different from those under the loading state. The soil sample is prone to shear failure during small deformation under multi-stage unloading. The shear strength is related to the initial consolidation pressure and unloading ratio. During the multi-staged unloading process, the number of contacts between particles does not change significantly, while the contact forces between particles decrease obviously.