A constitutive model for unsaturated cemented soils under cyclic loading

TL;DR

This paper develops an elastoplastic constitutive model for unsaturated cemented soils under cyclic loading, incorporating damage and suction effects, validated against experimental cyclic triaxial tests on natural loess.

Contribution

It introduces a novel elastoplastic model integrating damage mechanics and suction effects within a bounding surface framework for cyclic loading of unsaturated soils.

Findings

Model accurately predicts cyclic soil behaviour.

Captures bond degradation and suction effects.

Validated with experimental data from natural loess.

Abstract

On the basis of plastic bounding surface model, the damage theory for structured soils and unsaturated soil mechanics, an elastoplastic model for unsaturated loessic soils under cyclic loading has been elaborated. Firstly, the description of bond degradation in a damage framework is given, linking the damage of soil's structure to the accumulated strain. The Barcelona Basic Model (BBM) was considered for the suction effects. The elastoplastic model is then integrated into a bounding surface plasticity framework in order to model strain accumulation along cyclic loading, even under small stress levels. The validation of the proposed model is conducted by comparing its predictions with the experimental results from multi-level cyclic triaxial tests performed on a natural loess sampled beside the Northern French railway for high speed train and about 140 km far from Paris. The comparisons show the capabilities of the model to describe the behaviour of unsaturated cemented soils under cyclic loading.