Thermo-hydro-mechanical behavior of energy foundations in saturated glacial tills

Abstract

This study focuses on the effect of temperature- and –stress dependent hydraulic conductivities on the thermo-hydro-mechanical behavior of energy foundations installed in saturated glacial tills. A thermo-poroelastic model based on finite element method was developed and validated against field measurements from a case study in the literature, then was used to simulate four different energy foundations installed on the Urbana-Champaign campus of University of Illinois. Coupled thermo-hydro-mechanical properties were integrated into the numerical analyses based on laboratory characterization of the hydraulic conductivities of several soil samples at different temperatures and confining stresses. The results indicate that the transient evolution of pore water pressure, axial stress, and shaft resistance are significantly influenced by temperature- and stress- dependent hydraulic conductivity. Changes in axial stress and shaft resistance peak at early times when excess pore water pressures are highest. Long-term changes in axial stress and shaft resistance were less than the short-term peak values, highlighting the importance of considering the evolution of coupled soil properties to capture the peak response. This study demonstrates that consideration of coupled material properties is required to capture the coupled response of energy foundations in saturated glacial tills.