SIMPLIFIED ANALYSIS METHOD FOR VERTICALLY LOADED ENERGY PILE CONSIDERING LONGITUDINAL AND RADIAL THERMAL STRAIN

To explore the effect of temperature on the load transfer mechanism and related mechanical responses of energy piles, a plane transient temperature field equation was introduced to decouple the temperature field from the stress field. Based on the plane stress model, the energy pile and the surrounding soil of the pile are considered as a whole with coordinated deformation, and the radial thermal stress is calculated. It is then further combined with the hyperbolic load transfer model to modify the ultimate frictional resistance at the pile-soil interface. Considering the longitudinal thermal strain in the vertical load transfer equation, a method for analyzing the bearing characteristics of vertically loaded energy piles that can simultaneously consider the longitudinal and radial thermal effects is obtained. The incremental method is used to solve the governing equation of energy pile load transfer. The relevant mechanical responses such as the axial force of pile, shaft resistance, and pile displacement are obtained. Through a comparison with the existing literature, the rationality of the model is verified. Through parametric analysis, the load transfer characteristics of energy piles under the action of temperature and vertical force are studied. The results show that the temperature will change the load transfer characteristics of the energy pile, and increasing the operating temperature of the energy pile can slightly increase its bearing capacity. The calculation process of the method in this paper is clear, which can provide a reference for the design of energy piles.