A Calculation Method for Anti-freezing Fortification Length of Tunnel Entrance Section in Frozen Soil

Abstract

The invention discloses a frozen earth tunnel entrance section anti-freeze fortifying length computing method. The method comprises the following steps that S1, boundary conditions of tunnel surrounding rocks and linings are determined; S2, a steady-state temperature field with the surrounding rock temperature not changing with time is determined according to the boundary conditions of the tunnel surrounding rocks and the linings; S3, a temperature field with the surrounding rock temperature changing with time is determined according to the boundary conditions of the tunnel surrounding rocks and the linings; S4, the mean annual temperature of the tunnel cavern wall and the annual temperature amplitude of the tunnel cavern wall are computed according to the step 1, the step 2 and the step 3; S5, the temperature field distribution of the tunnel cavern wall is computed according to the mean annual temperature and the annual temperature amplitude of the tunnel cavern wall; and S6, the anti-freeze fortifying length is obtained according to a temperature field distribution formula. According to the method, theoretical formula derivation is conducted through heat transfer theory and mathematical and physical equation methods, and the different thicknesses of heat-insulation anti-freeze layers in different tunnel length positions are obtained, so that a reasonable segmental anti-freeze method is obtained.

Description

technical field [0001] The invention relates to the field of tunnel safety, in particular to a method for calculating the antifreeze length of an entrance section of a frozen soil tunnel. Background technique [0002] Since the temperature changes significantly from the tunnel entrance to a certain length inside the tunnel, the lining and insulation layer are affected by drastic temperature changes throughout the year, and the lining, insulation layer, and waterproof layer are more susceptible to damage from the freeze-thaw cycle caused by temperature changes on the structure. This caused a series of frost damage to the tunnel. Therefore, the structural design and insulation measures for a certain length from the tunnel entrance to the tunnel are different from other parts of the tunnel. The lining structure, thermal insulation performance and service life of the tunnel entrance to a certain length in the tunnel require higher standards. The structural design and thermal in...

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Problems solved by technology

[0003] However, the existing technical solutions do not study the temperature change characteristics based on the site, especially the temperature change characteristics based on the tunnel length direction, and do not consider the influence of changes in tunnel insulation and antifreeze measures on the temperature change along the tunnel length direction

There is also no method based on the combination of on-site temperature monitoring data, theoretical analytical solutions, and numerical simulations to propose the concept and law of the frost-resistant fortification length of permafrost tunnels.

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