针对高地温隧道施工期温度场受多种因素影响、演化机制复杂的问题，首先，通过现场调研获取某隧道围岩温度、环境温度及风速的分布特征，并基于室内试验探究不同温度下围岩、初期支护及二次衬砌材料热物性参数的变化规律；
其次，建立相应的非稳态数学模型并应用于COMSOL数值仿真软件计算，探究高地温隧道开挖—初期支护—二次衬砌施工全过程的温度场演化规律；
最后，利用多元函数回归分析方法，构建施工期初期支护和二次衬砌温度最大值的预测模型。研究结果表明： 1）随着隧道内温度的升高，围岩的热扩散系数显著呈现二次函数递减趋势，比热容呈二次函数递增，导热系数表现为上凹型二次函数下降趋势。2）初期支护和二次衬砌材料的热扩散系数同样遵循二次函数降低规律，比热容随温度升高先增后减，表明材料热储能特性的非线性变化。3）以隧道初期支护和二次衬砌内的最高温度为特征点分析发现，围岩温度和隧道环境温度的升高导致初期支护和二次衬砌内最高温度呈线性增加，回风速度的增大可有效促使温度呈先快后慢的下降趋势。
The temperature field in
tunnels with high ground temperatures is influenced by multiple factors during
their construction, and the field evolution mechanism is complex. To understand
this phenomenon, the distribution characteristics of the rock temperature,
surrounding temperature, and wind speed in a tunnel are investigated;
additionally, laboratory experiments are conducted to examine the change rules
of the thermophysical parameters of the surrounding rock, primary support, and
secondary lining materials under different temperatures. Subsequently, an
unstable mathematical model is implemented using the COMSOL numerical
simulation software. This model examines the evolution law of the temperature
field throughout the tunnel excavation process, including primary support and
secondary lining construction. Finally, a prediction model for the maximum
temperature of the primary support and secondary lining during the construction
period is established through multiple function regression analysis. Results reveal
the following key insights: (1) With increasing temperature in the tunnel, the
thermal diffusion coefficient of surrounding rock exhibits a quadratic
decreasing trend, specific heat capacity demonstrates a quadratic increasing
trend, and thermal conductivity decreases following an upward concave quadratic
function. (2) The thermal diffusion coefficients of the primary support and
secondary lining materials show a quadratic decreasing pattern. Meanwhile, the
specific heat capacity of these materials initially increases and then
decreases with rising temperature, indicating the nonlinear behavior of their
thermal energy storage characteristics. (3) When the maximum temperature in the
primary support and secondary lining of the tunnel is used as the characteristic
points, the increasing rock and surrounding temperature in the tunnel linearly
increases the maximum temperature in primary support and secondary lining.
Meanwhile, an increase in the return air speed effectively lowers the
temperature quickly at first and then slowly.
