软土能源桩温度蠕变的微观机理与热力耦合宏观模型研究

能源桩在我国经济发达的沿海沿江城市群有着广泛的工程应用空间。沿海沿江地区多为软土地质，而软土地基中能源桩在循环温度荷载作用下的长期沉降累积和稳定性涉及诸多复杂的多场耦合岩土力学机制。建立能够准确描述和预测这些力学机制的理论模型，一直是工程界和学术界为之努力的重要目标。近年来，对于具有清晰物理机制的宏观热力学模型的研究取得了根本性进展。本项目拟从研究软土在循环温度荷载作用下蠕变的微观机制入手，发展统一热力学理论框架和模型，由微观至宏观、定量定性描述软土的黏塑性耗散机制。其中核心问题涉及土颗粒-孔隙结合水的Thermo-Electro-Osmosis微观机制，以及如何将其嵌入热力学本构中从而宏观定量描述软土的热-力耦合性质。项目将发展多场耦合的轴对称有限元程序对软土中能源桩问题进行分析和预测，并运用离心机试验、中空厚壁圆柱实验等手段进行理论验证，为能源桩在沿海沿江地区应用提供理论和实验基础。

Energy piles possess wide engineering opportunities in China’s developed coastal and riparian urban agglomerations. The ground condition of these areas are usually soft clays, in which the energy piles, under cyclic thermal loads, may undergo long-term accumulated settlements and stability problems, which involves complex multi-field geotechnical mechanisms. Developing a theoretical model that is able to accurately describe and predict these mechanisms has long been a major task to the engineering and academic researchers. In recent years, research on the macro thermodynamic models with clear physical mechanisms has got fundamental progress. The project aims to start from the study of the micro mechanisms of thermal creeps of soft clays under cyclic thermal loads. Then, a unified thermodynamic theoretical framework and model is going to be developed which is able to quantitatively and qualitatively describe the visco-plastic dissipative mechanism of soft clays, from micro to macro. The key question of the project is to study the Thermo-Electro-Osmosis micro mechanism between clay particles and the pore bound water and how to implement it into the thermodynamic constitutive model in order to quantitatively describe the macro thermal-mechanical-coupled properties of soft clays. The project is going to develop multi-field axisymmetric finite-element codes for analyzing and predicting problems of energy piles in soft clays. Centrifuge model tests and thick-walled hollow cylinder tests will be used for validating the proposed theories. The project is expected to provide theoretical and experimental support for the application of energy piles in coastal and riparian areas.