考虑温度影响的能源桩桩–土界面荷载传递模型

A load transfer model of energy pile-soil interfaces under temperature variation

为深入揭示温度对能源桩力学特性的影响,考虑能源桩桩–土界面法向温度应力增量对初始剪切刚度的影响,对传统桩–土界面荷载传递双曲线模型进行修正,并通过合理假设桩身及桩周土中温度场分布,计算得到桩–土界面法向温度应力,建立考虑温度影响的桩–土界面荷载传递模型。同时,选取宁波地区典型软黏土开展不同温度下能源桩承载力特性模型试验,将计算结果与模型试验结果进行对比,结果表明:升温有助于提高能源桩单桩的承载力;桩周土温度、Q-s曲线计算结果与实测值较为一致,验证了能源桩桩–土界面荷载传递模型的合理性;能源桩运行使得桩、土体温度升高,桩、土之间的法向应力增大,相同条件下能源桩上部(0.7 m以上)桩侧摩阻力随温度的升高(30℃→45℃→60℃)有一定的增大,发挥充分,下部反之。

To reveal the influence of temperature on the mechanical properties of energy piles,a traditional hyperbolic model for pile-soil interface load transfer was revised by considering the influence of the normal temperature stress increment on the initial shear stiffness at the interface of pile and soil. The temperature field distributions in the pile body and surrounding soil were assumed,and the normal temperature stress of the pile-soil interface was calculated,then the load-transfer model of pile-soil interfaces considering the influence of temperature was established. The bearing capacity of energy piles in the typical soft clay in Ningbo area was studied by modelling test. The experimental results were compared with the calculated results. It is shown that the temperature helps to improve the bearing capacity of the energy pile,and that the calculated results of Q-s curve are consistent with the measured values,which verifies the rationality of the load transfer model of the energy pile considering the influence of temperature. The operation of energy piles leads to temperature increasing in pile and soil,and the normal stress between pile and soil increase too,which cause the shaft resistance of the upper part of the energy pile(above 0.7 m) to increase with temperature(30 ℃→45 ℃→60 ℃) under the same conditions of calculation,but in the lower part,the opposite occurs.