In the geotechnical design of energy piles using various methods such as simplified one-dimension analyses and finite element simulations, the pile temperature change is a crucial input parameter. The current analysis methods usually ignore the non-uniformity of temperature over the pile cross-section and adopt the maximum temperature change as the input parameter. However, this method cannot correctly describe the thermomechanical performance of energy piles and may lead to over-design. This paper provides an analytical model to determine the representative temperature change for the geotechnical design of energy piles. To this end, the expression of the average temperature change corresponding to the average strain of the pile cross-section is firstly derived according to the assumption of strain compatibility. The representative temperature change calculation approach is further proposed by introducing the thermal resistance and heat source model. Comprehensive validation of the proposed model is presented by using experimentally verified numerical simulations. Besides, climatic conditions, heat exchange pipe configurations, and pile diameter on the representative temperature change are studied. The results show that the proposed model is capable of calculating the representative temperature change effectively. Overall, the proposed model provides a reliable approach to determining the representative temperature change used in the geotechnical design of energy piles, and its feature that avoids cumbersome numerical simulations and computing make it have extensive application prospects in the geotechnical design of energy piles.

在使用简化一维分析和有限元模拟等各种方法的能量桩的岩土工程设计中，桩温变化是一个关键的输入参数。目前的分析方法通常忽略桩截面温度的不均匀性，采用最大温度变化作为输入参数。然而，这种方法不能正确描述能量桩的热力学性能，并可能导致过度设计。本文为能量桩的岩土工程设计提供了一个确定代表性温度变化的分析模型。为此，首先根据应变相容性假设推导出与桩截面平均应变对应的平均温度变化表达式。通过引入热阻和热源模型，进一步提出了具有代表性的温度变化计算方法。通过使用经过实验验证的数值模拟，对所提出的模型进行了全面验证。此外，还研究了气候条件、换热管配置和桩直径对典型温度变化的影响。结果表明，所提出的模型能够有效地计算具有代表性的温度变化。总体而言，所提出的模型为确定能源桩岩土工程设计中使用的代表性温度变化提供了一种可靠的方法，其避免了繁琐的数值模拟和计算的特点使其在能源桩的岩土工程设计中具有广泛的应用前景。