Abstract
Oxygen deficiency and coldness are the main challenges for highway tunnel construction in high-altitude areas such as western Sichuan plateau. The artificial oxygen supply and anti-freezing structure in the tunnel construction process has a significant impact on vocational health and the environment. Thus, the conditions of tunnels need to be carefully evaluated before construction. However, the current design code for tunnel construction contains few instructions about these aspects. This paper attempts to establish a simple evaluation method to guide the construction design by analyzing the oxygen partial pressure of trachea, the mean temperature of the coldest month, and the maximum freezing depth for tunnel projects in western Sichuan plateau. Based on the on-site meteorological monitoring at different altitudes of three typical tunnels in the western Sichuan plateau and the comparative analysis of the existing meteorological data, the corresponding relationships between the three parameters and the altitude were investigated. The thresholds by altitude for grading the tunnels are identified as 2100 m and 4200 m, respectively. The highway tunnels in the western Sichuan plateau are graded in three categories, namely, general-altitude tunnels, high-altitude tunnels, and ultra-high-altitude tunnels. The corresponding measures of oxygen supply and freezing prevention for different graded tunnels are recommended. The results would provide a basis for the design and construction of new tunnels and enhance the service life and operations safety of the tunnels in western Sichuan plateau and other similar high-altitude areas.
Highlights
Tunnels are very important for transportation in mountain areas as they can significantly reduce transportation time and enhance transportation safety
We verify the changing patterns of oxygen deficiency and cold climate as altitude ascends on the basis of meteorological monitoring near the portals of three representative tunnels in western Sichuan plateau
After altitude coldness were established and calibrated for western that, we that, we proposed grading standard forbytunnels altitude considering health, labor proposed a gradingastandard for tunnels altitudebyconsidering vocationalvocational health, labor efficiency, efficiency, and recommended appropriate design foroftunnels of different grades
Summary
Tunnels are very important for transportation in mountain areas as they can significantly reduce transportation time and enhance transportation safety. If the meteorological data in town area is used instead to guide the construction of tunnels in mountains, the errors in meteorological information may cause damage in tunnel structure [15] or extra construction cost [16] It is, not the region but every tunnel that needs to be graded in western Sichuan plateau. We verify the changing patterns of oxygen deficiency and cold climate as altitude ascends on the basis of meteorological monitoring near the portals of three representative tunnels in western Sichuan plateau. Ensurethe tunnel construction efficiency and safety, we quantitatively evaluate hypoxia risks at different altitudes and western Sichuan plateau into three grades, that is, general-altitude tunnel, high-altitude tunnel, and propose grading rules based on our data, literature, andgrading existing regulations.
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