Finite element analysis of vibratory roller response on layered soil systems

The objective of this study is to quantify the relationships between continuous compaction control (CCC) roller soil stiffness measurements and subgrade and base lift moduli and thickness for quality control applications on fully compacted soils (e.g. proof rolls). This is done using plane strain, dynamic, time-domain finite element (FE) analyses. The FE model is calibrated against field data from two construction sites and is shown to capture the time-varying loading characteristics of the roller and the force–deflection behaviors of the underlying soil surface. The model is then used to explore the effects of subgrade and base moduli and the thickness of the compacted base layer on roller-measured stiffness values. The roller-measured stiffness increases with lift thickness and with subgrade and base moduli, showing sensitivity to both changes in lift thickness and in soil materials commonly observed in practice. The time-varying contact area is shown to have negligible effects on the roller-measured values. This observation is justified using a plane strain analysis of a layered elastic medium subjected to a dynamic strip loading.