持续低温环境下混凝土灌注桩温度场模拟研究

Simulation Study on Temperature Field of Bored Concrete Pile under the Environment of Sustained Low Temperature

以青藏铁路为依托,采用人工气候模拟试验箱在冻土层中进行灌注桩浇筑试验,并运用ANSYS软件建立模型对低温环境下冻土-灌注桩温度场变化情况进行了模拟分析。结果表明:混凝土浇筑后,灌注桩桩心温度最高,桩体表面温度最低,受水泥水化热影响桩心温度有短暂温升随后开始下降,入模5 h桩心温度降至0℃,入模30 d时降至-4.9℃,冻土环境极不利于混凝土强度的增长;混凝土入模时靠近桩体表面的冻土层逐渐融化但很快又降至0℃以下;依照试验实测温度场数据校核的模型可用于预测不同入模温度、不同桩径、不同冻土温度条件下灌注桩混凝土水化温度变化范围。

Taking the Qinghai-Tibet Railway as the background,the artificial climate simulation test box was used to carry out the pouring test of the bored concrete pile in frozen soil,and the change of the temperature field of the frozen soil-bored concrete pile under low temperature environment was simulated and analyzed through the model established by ANSYS software.The results show that the core temperature of the bored concrete pile is the highest,while its surface temperature is the lowest,after the concrete is poured.With the effect of hydration heat of cement,the temperature of the pile core increased briefly and then began to decrease.The core temperature drops to 0℃after 5 hours,and to-4.9℃after 30 days of moulding.Therefore,the frozen soil environment is extremely unfavorable for the growth of concrete strength.When the concrete is put into the mold,the frozen soil layer close to the surface of the pile is gradually melted,but it soon drops below 0℃.The model calibrated according to the measured temperature field data can be used to predict the range of hydration temperature of bored concrete pile under different molding temperatures,different pile diameters,and different frozen soil temperatures.