Abstract
High geotemperatures are encountered during tunnel construction in areas with complex geological structures, which can seriously affect personnel and equipment in the process of tunnel construction and operation. The Nige tunnel, a deep-buried extra-long tunnel, was selected to monitor the geotemperature during construction. The air, rock, and water temperatures during the tunnel construction were measured at the tunnel face, and the actual temperatures of the rock or water body at the tunnel face were measured by advanced drilling. The variation trends of the water temperature, air temperature, and flow of water with the tunnel mileage were analyzed. The differences in three measured rock temperatures in three advanced drillings were revealed. The results showed that the Nige tunnel had a maximum water temperature of 63.4 °C, maximum rock temperature (Rock T) of 88.8 °C, and maximum air temperature (Air T) of 56.4 °C. Increasing trends of the air, rock, and water temperatures with the tunnel’s horizontal distance and the buried depth (vertical depth) were obvious, and the geotemperature gradient was approximately 7.6 °C per 100 m. Additionally, the variation laws of the construction ambient temperature with time in a complete construction cycle showed four stage characteristics, and each stage presented different mathematical relationships. These findings will provide guidance for the construction of high geotemperature tunnels in future.
Highlights
With the rapid development of China’s transportation network, highway and railway transportation began to expand to high mountain and canyon areas, with high construction difficulty and complex geological conditions [1,2]
The air temperature was affected by the water temperature, the of theoftunnel
It can be seen from the figure that for the left tunnel, the difference of the first first measured rock temperature temperature is the the largest largest at at both both ends ends of of the the advanced advanced drilling, drilling, with with aa difference of
Summary
With the rapid development of China’s transportation network, highway and railway transportation began to expand to high mountain and canyon areas, with high construction difficulty and complex geological conditions [1,2]. It is necessary to study the temperature field of high geotemperature tunnels. In the tunnel survey stage, obtaining a relatively accurate prediction and classification of the heat damage of the tunnel based on the temperature of the surrounding rock has become an engineering problem [10,15,16]. Temperature effects have a significant influence on rock bursts at high geotemperatures [2]. The evolution law of the geotemperature of the tunnel plays an important role in revealing the mechanism of the rock burst. Most studies are based on laboratory mechanical test results, which vary the laws of the mechanical parameters of the rock with the temperature under hightemperature conditions [1,19]. The air temperature of the tunnel construction area was tested continuously for six construction cycles, and the mathematical relationship between the air temperature and time was proposed
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