长期热循环下桩土力学特性及作用机理研究

项目名称： 长期热循环下桩土力学特性及作用机理研究

项目编号： No.51478228

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 建筑科学

项目作者： 刘干斌

作者单位： 宁波大学

项目金额： 82万元

中文摘要： 热交换桩技术是与桩基工程协同施工的、新的建筑节能技术。在长期热循环作用下，桩土力学特性、界面荷载传递及作用机理等是亟待解决的关键科学问题。为此，本项目采用室内试验、模型试验、理论建模和数值模拟相结合的方法，首先对桩周土开展热排水三轴剪切试验、热固结试验，定量地揭示温度对土的强度、固结和应变累积特性的影响，判定土的热硬化或软化规律；其次采用模型试验方法，开展不同温度增量及循环加热/卸热作用下的桩基静载荷试验及测试，揭示热交换桩的长期热循环作用机理；在此基础上，建立桩土界面剪应力-位移模型及桩土系统数值模型，将计算结果与模型试验结果相互验证，评价长期热循环效应对桩基承载力的影响，进而优化热交换桩的设计计算，提出相应的技术措施。本项目一方面旨在揭示复杂环境条件对热交换桩基础工程特性的影响，促进学科交叉，另一方面为热交换桩基础的优化设计提供必要的科学依据和技术支撑。

中文关键词： 热循环作用；桩基础；力学特性；模型试验；数值模拟

英文摘要： Heat exchanger pile technology is one of the new building energy saving techniques in which the heat exchanger is constructed together with pile foundation. Under the long term cycling thermal load, mechanism and changes of mechanical properties of pile and soil, and of behavior of pile-soil interface are the key are key scientific problems required to be solved in the design of heat exchanger pile. Therefore, a method of combining laboratory test, model test, theoretical modeling with numerical analysis is used in this subject. Firstly, the thermo-drainage consolidated triaxial shear test and the thermal consolidated test are carried out on the soil around the pile. The effects of temperature on the strength, consolidation and strain accumulation of soil are analyzed quantitatively, and the change rules of heat hardening or softening of soil under different temperature are revealed. Secondly, model test method is used, and static loading tests are carried out under different temperature and under the cyclic heating/cooling case for a certain temperature increment, then the long-term cycling thermal effect of the heat exchanger piles are revealed. Finally, a shear model of pile-soil interface and a numerical calculation model for the heat exchanger pile-soil system are developed，then mutual verification are executed on numerical calculation results and model test results. Furthermore, the calculated result are used to assess the influence of the long-term thermal cycling effect on the bearing capacity of pile foundation, and to optimize the design of heat exchanger pile, and to put forward the corresponding technical measures. The results of this subject, on the one hand, can reveal the mechanical properties of heat exchanger pile and soil under complex environmental conditions, develop multi-physical field soil mechanics and promote inter-disciplinary, on the other hand can provide an important scientific and technical support for the design and application of heat exchanger pile.

英文关键词： thermal cycling effect;pile;mechanical property;Model Test;Numerical Modeling