饱和黏土中能源群桩热力特性模型试验研究

Model test on thermal-mechanical characteristics of energy pile groups in saturated clay

为研究饱和黏土地基中静钻根植能源群桩不同运行方式的热力特性,采用自行设计的模型试验系统,测试温度条件下模型单桩和群桩的热力响应。通过埋置传感测试元件,得到桩顶位移、桩身应力、桩和桩周土温度、桩周水平土压力及孔隙水压力。结果表明:由于桩间热扩散,加热桩会对周围非加热桩造成影响,导致非加热桩桩身温度增加、桩顶位移上升,能源群桩的平均换热性能较单桩低;制冷工况下群桩的桩顶位移变化绝对值大于加热工况,需要考虑以确保安全性;由于群桩效应,与单桩相比,能源群桩桩顶位移变化更大,桩身附加温度应力更小;能源群桩的热力特性受运行能源桩数量影响,运行数量越多,温度对能源群桩的热力特性影响越显著,桩周土压力、孔隙水压力变化值越大。

In order to study the thermal characteristics of pre-bored grouted planted energy pile groups in saturated clay foundation under different operation modes,a self-designed model test system is used to examine the thermal response of single pile and pile group.By embedding sensing test elements,data on pile top displacement,pile stress,pile and surrounding soil temperatures,horizontal soil pressure,and pore water pressure are collected.Findings show that the heated pile influences adjacent unheated piles through thermal diffusion,leading to increased pile body temperature and top displacement.Moreover,the overall heat transfer efficiency of energy pile groups is lower than that of single piles.The absolute displacement change at the pile top in energy pile groups is greater under cooling conditions than under heating conditions,necessitating safety considerations.The group effect results in larger pile top displacements and lower additional thermal stresses in energy pile groups compared to single piles.Furthermore,as the number of energy piles in a group increases,the thermal characteristics become more pronounced,accompanied by greater variations in horizontal soil pressure and pore water pressure around the piles.