Study on Heat Transfer Characteristics of Energy Piles in Stratified Seepage Soil

Taking energy piles as the reasearch object, combined with the actual geological layered seepage, the differential equation for heat transfer of energy piles was established according to the principle of energy conservation. The excess temperature equation for heat transfer of energy piles in layered seepage soil was obtained by the method of seperation variables and Laplace Transform. The calculation software was programmed to verify the accuracy of the heat transfer model. Based on the model, the influence for thermophysical properties of soil and seepage velocities on the distribution of excess temperature was discussed. The results showed that changes in thermophysical properties of adjacent soil layers under and below the piles would influence the excess temperature distribution at the top and bottom of the piles, and had a certain impact on the total heat transfer of piles. Seepage had a significant impact on the distribution of excess temperature in stratified soil. At the same distance apart from the centers of energy piles, the excess temperature of the upper-stream was lower than that of the lower-stream in the same soil layer. The higher the seepage velocity, the more significant the isotherm deviation of excess temperature in the soil layer; the more obvious the heat transfer, and the higher the heat exchange efficiency of energy piles.