A constitutive modelling approach towards performance-based intelligent compaction

This study proposes a numerical approach to further advance Intelligent Compaction (IC) tech-nology by knowing how the initial states of the unsaturated soil (determined by the initial void ratio 𝑒0 and initial degree of saturation 𝑆𝑟0) can influence the performance of road pavements. The approach em-ploys a simplified constitutive model for unsaturated soils which is based on the effective stress concept and bounding surface plasticity. The model is used to simulate the compaction of the soil layer and sub-sequent deformations during operation under traffic loads. With the approach, the effects of 𝑒0 and 𝑆𝑟0 on void ratio changes Δ𝑒 during compaction as well as during operation (e.g., under traffic loads) can be captured, which enables a step-change improvement in predicting the response of compacted materials at different initial states. The approach is demonstrated and evaluated by several numerical examples. The simulation results for compaction and traffic loads and the laboratory test results for compaction indicate that higher initial void ratios lead to greater void ratio changes when the effect of 𝑤 is less significant than the effect of 𝑒0.