Analytical solutions for thermal–mechanical coupling of energy piles in double-layer soil

Abstract

Energy piles have gained a lot of attention in recent years as an environmentally responsible way to use renewable energy. The aim of this research is to analyze the behavior of energy piles in double-layer soil when subjected to mechanical and thermal loads, as well as combined thermomechanical loads. To achieve this, the study proposes analytical solutions for axial stress, strain, and displacement, which are based on principles such as equilibrium, kinematics, thermoelastic constitutive relationships, and elastic constitutive relationships of the pile-soil interface. These analytical solutions have been proven to accurately predict the behavior of energy piles under various loads. This paper analyzes several factors that affect the thermal–mechanical coupling analytical solutions for the energy pile, including soil lateral restraint, soil depth, pile end restraint, thermal expansion coefficient of the pile and mechanical load. In conclusion, the analytical solutions presented in this paper make us better understand the pile-soil interaction behavior and load transfer mechanism of semi-floating energy piles rather than ideally end-bearing piles nor ideally fully floating piles, thus can be used as a simple tool for the design and construction of energy piles in double-layer soil.