Energy saving technology of tunnel air based on foundation pit trenches

Wang Shengnan, Gong Yun, Liu Qiang, Gao Xiliang and Yuan Yanping


Investigates the difference of the foundation trench section under different supporting forms of the foundation pit, finds that there is a large amount of “free” space in the foundation pit trench for burying pipes or laying civil air channels, and the volume of foundation trench increases several times with the increase of foundation pit depth, which is very suitable for the application of tunnel air technology. Taking a garage tunnel air project in Nanning area as an example, adopts the two-dimensional steady-state heat transfer model established by MATLAB software to simplify the calculation of tunnel wind heat transfer process. The simulation results show that the annual soil temperature fluctuation of the space below 3 m is very small, and with the increase of buried depth, the thermal inertia effect of the soil becomes more and more obvious. The annual highest temperature at the buried depth of 6 m occurs in December, which achieves a good inter-seasonal heat storage. At the same time, with the increase of tunnel length, the cooling capacity of unit tunnel length decreases significantly. From the consideration of economic rationality, suggests that the system pipeline should not exceed 300 m. Finally, by comparing the tunnel air system with the multisplit system, the tunnel air system can save nearly 130 000 kWh of electricity every year, and the static recovery period is about 6.7 years. The energy saving benefit is remarkable in the whole life cycle.