A prediction model for the loading-wetting volumetric behavior of unsaturated granular materials

Abstract

Geotechnical structures made of granular material tend to be unsaturated during their service life. However, there is presently a lack of sufficient research and studies on their volumetric behavior under unsaturated conditions. In this study, loading and wetting induced volumetric behavior of granular materials in the unsaturated state was studied within a moisture content-based framework. Recycled crushed brick (CB) and excavation waste rock (WR) were the granular materials used in this research to promote sustainable construction. Several loading, unloading, and wetting state paths were investigated with respect to virgin compaction surfaces (VCS) developed using groups of compaction curves. The obtained experimental data was utilized to develop a constitutive model capable of predicting wetting-induced volume changes of granular materials in a net stress range of 100–4000 kPa and gravimetric moisture content range of 3.6% for WR, and 7.5% for CB to saturation. The model was verified by undertaking several independent state paths on independent materials and comparing the experimental responses with those predicted using the model. The proposed model is featured with simplicity in acquiring the model input parameters with the aim of filling the existing gap between the theoretical and real-life application of unsaturated soil mechanics. An application of the model can be the basis for the prediction of the settlement of a granular geotechnical structure that is being externally loaded and is subject to changes in moisture content due to climatic effects.

Keywords

• Loading-wetting path
• Recycled materials
• Unsaturated granular material
• Volume change
• Virgin compaction surface
• MPK framework