Swell and shrinkage strain prediction models for expansive clays

• Analytical models were developed for swell and shrink predictions in expansive soils.
• New models were developed for predicting swelling and shrinkage in expansive soils.
• Comparison analysis was made between new and old models for validation.
• Models with test procedural information and moisture content variations predict well.

A comprehensive laboratory investigation was conducted to study volume change behaviors of five different types of expansive clayey soils sampled from various regions in Texas, USA. The laboratory test results, which were presented in an earlier paper, are analyzed here to evaluate existing correlations that can be used to predict swell and shrink-related displacements in these soils. The test database is also used to develop newer and practical models for predicting volume change-related soil properties. Models developed here used soil plasticity and compaction properties as independent variables. Newer models, that rely on seasonal compaction moisture content variations in the subsoils, were introduced to estimate both volumetric and vertical swell and shrinkage strains expected under civil infrastructure. The developed correlations, along with the existing models, were then used to predict vertical soil swell movements of four case studies where swell-induced soil movements were monitored. This comparison analysis showed that the model dependency on the volume change test procedural information and moisture content variation due to seasonal changes will lead to better prediction of swell movements in subsoils. Future research directions and recommendations are provided on implementation of the developed models in a realistic estimation of swell movements of infrastructure construction projects.