深层埋管式新型能量桩热力学特性及承载力计算方法研究

The energy pile is a kind of shallow geothermal utilization building energy saving technology developed on the basis of ground source heat pump. A new type of deep buried pipe type energy pile structure with the upper part of the energy pile and the lower part of the deep well heat transfer tube is proposed. It can effectively improve the heat transfer efficiency and make full use of the thermal energy below the pile foundation which can meet the energy demand of the superstructure independently. Through means of theoretical analysis, model test and numerical simulation, the thermodynamic characteristics and calculation method of the bearing capacity of the new type energy pile structure are studied. Through the theoretical analysis of the heat transfer mechanism of variable cross-section heat conduction medium conditions, a heat transfer model based on analytical solution is established, and the temperature field distribution characteristics of new energy piles and their influence on the structural stress field are studied. Model test and numerical simulation are carried out to study the mechanical response characteristics and bearing characteristics of pile under different load and temperature field conditions, and research the influence of deep well on the bearing capacity of the new energy pile end. On this basis, the simplified analysis model and calculation method of bearing capacity of the thermal mechanical response of the new energy pile is established. The research results will provide a strong theoretical basis for the application of the new type energy pile with deep buried pipe, promote the further improvement of energy pile technology, and make a positive contribution to the utilization of geothermal energy in china.

能量桩系统是在地源热泵的基础上发展而来的一种浅层地热利用的建筑节能技术。本项目提出一种上部为能量桩，下部为深井换热管的深层埋管式新型能量桩结构。该结构综合了传统地源热泵深层换热及桩内埋管式能量桩节约占地和高换热效率等优点，能独立满足上部结构的能源需求。本项目结合理论分析、模型试验与数值仿真，深入研究新型能量桩结构的热力学特性及承载力计算方法。通过理论分析变截面变导热介质条件的换热机理，建立基于解析解的传热模型，研究新型能量桩的温度场分布特征及其对结构应力场的影响规律；采用模型试验与数值模拟，研究不同荷载条件和温度场条件下桩体的力学响应特征及承载特性，分析深井对新型能量桩桩端承载力的影响。在上述研究基础上，建立新型能量桩热-力学响应的简化分析模型及承载力计算方法。研究成果将为新型能量桩的应用提供坚实的理论基础，促进能量桩技术的进一步完善，为我国地热能源的利用做出积极贡献。

能量桩系统是在地源热泵的基础上发展而来的一种浅层地热利用的建筑节能技术。本项目提出一种上部为能量桩，下部为深井换热管的深层埋管式新型能量桩结构。该结构综合了传统地源热泵深层换热及桩内埋管式能量桩节约占地和高换热效率等优点，能独立满足上部结构的能源需求。本项目紧紧围绕新型能量桩传热规律与热力响应特征两个关键科学问题展开一系列理论和试验研究，并建立了建立深层埋管式能量桩示范基地，为项目实施提供了原位测试条件。考虑新型能量桩结构特征，通过理论与试验分析了变截面变导热介质条件的换热机理，明确了新型能量桩的温度场分布特征及其对结构应力场的影响规律。通过制冷或制热工况的原位试验获得在温度荷载作用下桩端阻力、桩顶沉降以及桩身应变等桩土相互作用规律，评价热交换过程对结构安全的影响。通过数值模拟研究不同荷载条件和温度场条件下桩体沿桩深方向及横截面轴向的力学响应特征，明确了换热过程对基桩承载力的影响规律。在上述研究基础上，提出了新型能量桩热-力学响应的简化分析模型。研究成果将为新型能量桩的施工及设计提供一定的理论基础，促进能量桩技术的进一步完善，为我国建筑行业减少碳排放做出积极贡献。