温度荷载作用下能源桩的力学特性

Mechanical properties of energy pile under temperature load

为了研究能源桩的温度场分布及其在循环温度作用下的力学特性,进行了室内模型试验和数值模拟分析。首先,开展室内模型试验,对黏土地基中的能源桩设置不同温度荷载及循环次数,测试其桩顶位移、桩端土压力、桩侧摩阻力及桩周土温度场分布,分析温度荷载下桩的力学特性及变化规律;其次,以模型试验为原型,利用COMSOL软件建立能源桩-土力学模型,开展不同温度荷载和循环次数下的能源桩数值模拟研究。结果表明:能源桩-土温度场中部的温度传递相较于两端更迅速;升温阶段,温度越高桩顶位移越大;降温阶段,温差越大引起的桩顶位移改变量越大;每次温度循环均会导致桩顶产生附加沉降;桩端土压力和桩侧摩阻力随温度的升高呈逐渐增大的趋势,温度变化导致桩身多处出现负摩阻力,且负摩阻力随温度的升高和循环次数的增加而增大,在设计时要适当考虑。

The distribution of the temperature field of the energy pile and its mechanical properties in clay under the action of circulating temperature were analyzed by laboratory model test and numerical simulation.Firstly,through laboratory model test,the displacement of energy pile top,soil pressure at pile end,lateral friction of pile and distribution of soil temperature field around pile under different temperature loads and cycle times were tested.The mechanical properties and change rules of pile under temperature load were analyzed;Secondly,the model test was used as the prototype to establish the energy pile-soil mechanical model by using COMSOL software.It carried out the numerical simulation of the mechanical properties of the energy pile under different temperature loads and cycles,and the simulation results were compared with the model test results.The results show that the soil temperature diffusion speed in the middle part of the energy pile is faster than that at both ends.In the heating stage,the higher the temperature,the greater the displacement of pile top.In the cooling stage,the greater the temperature difference,the greater the displacement modification variable of pile top.Each temperature cycle leads to additional settlement of the pile top.The soil pressure at the pile end and the lateral friction of the pile gradually increase with the increase of temperature,which led to negative friction at many parts of the pile body.The negative friction increased with the increase of temperature and cycle times,which should be considered properly in the design.