In order to discuss the heat transfer performance of a vertical U-tube in protective engineering

the changes in the inlet and outlet water and soil temperatures were analyzed under two different conditions based on a ground source heat pump experimental platform for underground engineering. The underground temperature was measured during the test

and the thermal diffusion ability of the soil was studied. The results showed that the heat exchange gradually decreased under the condition of 24 h continuous operation. Under the condition of 12 h intermittent operation

the local heat exchange at the beginning was significantly smaller than that of the continuous operation

but the average heat transfer capacity was larger than that of the continuous operation. A continuous operation model should be used when protective engineering deals with raids

while the thermal stability time and heat exchange at that time should be recommended as indexes to evaluate the ability of a buried pipe system when dealing with raids. The time and heat exchange measured in this experiment were 14 h and 1 310.4 kJ/m. However

an intermittent operation model should be adopted when the engineering is used over a long period because it effectively slows down the heat accumulation.