周期性地表温-风温下地铁隧道围岩蓄热分析

Analysis on heat storage in tunnel surrounding rock of subway under effects of periodic ground temperature-airflow temperature

为预估浅埋地铁隧道围岩蓄热量,采用有限体积法,建立周期性地表温及隧道风温协同作用下的地铁隧道围岩瞬态传热模型;选取合适的无因次准数离散化模型,并编制解算程序;研究围岩无因次温度场在不同毕渥数和傅里叶数下的分布特征,绘制隧道壁面不稳定换热准数诺谟图,通过查图评估隧道围岩不同年周期内的总蓄热量,结合实例验证模型的正确性。结果表明:双重周期性温度边界影响范围内的围岩无因次温度均按简谐波波动;隧道上覆岩层受双重周期性温度波叠加作用的影响较大,其秋季温度会显著升高;隧道围岩在年周期内总体表现为蓄热,年蓄热量逐年小幅下降,最后趋于稳定。

In order to predict heat storage capacity of shallow underground tunnels'surrounding rock,a transient heat transfer model of the rock under synergistic effects of periodic surface temperature and tunnel wind temperature was developed by adopting finite volume method.Then,a suitable factor-less quasidiscrete model was selected and a solution procedure was prepared.Distribution characteristics of dimensionless temperature field in surrounding rock at different Biot numbers and Fourier numbers were investigated,an unstable heat transfer quasi-nomogram of tunnel walls was drawn,and total heat storage for the rock in different annual cycles was assessed by checking the map.Finally,the model's was verified through case studies.The results show that dimensionless temperature within influence of double periodic temperature boundary fluctuates according to simple harmonic waves,while the overlying rock layer of the tunnel is more affected by superposition of double periodic temperature waves,whose temperature increases significantly in autumn.Moreover,as the surrounding rock generally exhibits heat storage during yearly cycle,its annual storage decreases slightly from year to year and eventually becomes stable.