循环温度场作用下能量桩热-力学性能的试验研究

EXPERIMENTAL STUDY ON THERMO-MECHANICAL PROPERTIES OF ENERGY PILES UNDER ACTION OF CYCLIC TEMPERATURE

能量桩是集建筑桩基和地源热泵于一身,既起到承担上部荷载的作用,同时也是与浅层地温能进行热交换的媒介,具有节约能源、减少污染等优点。通过室内模型试验,对黏土地基中能量桩在温度荷载作用下桩顶位移、桩端压力、桩身温度应力及桩侧摩阻力进行研究,得出温度升、降使得桩体内产生拉、压应力,应力沿桩身从桩顶到桩端先增大后减小,应力最大值靠近桩体下半部分;桩端压应力随温度升高而增大,最大压应力随温度循环次数的增加而逐渐减小;桩侧摩阻力随温度升高而增大,加热和制冷过程中,桩体分别在上半部分和下半部分产生负摩阻力。

Energy piles are combinations of pile foundations and ground source heat pumps.They not only bear the upper building load but also act as media for heat exchange with the shallow geothermal energy,which are of advantage on energy-saving and pollution reduction.Based on indoor model tests,the displacement of pile tops,pile bottom pressure,temperature stress and side friction resistance of energy piles in clay foundation under the action of cyclic temperature were experimentally studied.It was concluded that the rise or fall in temperature could also cause tensile and compressive stress in piles,stress increased first and then decreased in pile shafts from tops to bottoms of piles,and the maximum stress was close to the lower middle parts of piles.The compressive stress of pile bottoms increased with the increase of temperature,and the maximum compressive stress decreased with the increase of temperature cycles.Friction resistance of pile sides increased with the increase of temperature.During the period of being heated and cooled,and the negative friction resistance would be generated on upper parts and lower parts of piles respectively.