|Table of Contents|

Cooling effect of thermosyhpon subgrade for Qinghai-Tibet Highway(PDF)

《交通运输工程学报》[ISSN:1671-1637/CN:61-1369/U]

Issue:
2016年04期
Page:
45-58
Research Field:
道路与铁道工程
Publishing date:

Info

Title:
Cooling effect of thermosyhpon subgrade for Qinghai-Tibet Highway
Author(s):
JIN Long;  WANG Shuang-jie;  MU Ke;  PENG Hui
State Key Laboratory of Road Engineering Safety and Health in Cold and High-Altitude Regions, CCCC First Highway Consultants Co., Ltd., Xi’an 710075, Shaanxi, China
Keywords:
subgrade engineering;  thermosyphon subgrade;  field observation;  numerical simulation;  shady-sunny slope effect;  cooling effect
PACS:
U416.168
DOI:
-
Abstract:
In order to analyze the engineering effect of thermosyphon subgrade in permafrost regions and quantitatively evaluate its cooling effect, the 11 years’ observational data were collected from the thermosyphon subgrade test project of Qinghai-Tibet Highway, the ground temperature characteristics, temperature field profiles and freezing-thawing process of thermosyphon subgrade were analyzed, and the horizontal thermal budget near the thermosyphons under the influence of shady-sunny slope effect was evaluated. A three-dimensional unsteady coupled air-thermosyphon-foundation computation model was proposed, and the cooling effects of thermosyphon subgrades with different structures, such as one-side vertical type, one-side inclined type, two-side vertical type and two-side inclined type, were investigated. Measured result shows that the monitoring data indicates that the ground temperature of thermosyphon subgrade at sunny side is about -1.5 ℃, 3.0 ℃ lower than the value of traditional subgrade, and the lowest ground temperature at shady side can reach to -2.1 ℃. During 11 years’ operation of thermosyphon subgrade, the permafrost table at sunny side elevates about 0.95 m, and basically reaches to the level of natural foundation. The mean annual actual powers of thermosyphon subgrades at shady side and sunny side are about 69.80 and 54.07 W, respectively. During the previous 5 years, the thermosyphon presents a larger power. After 6th year, the power gradually decreases, and the thermal state of subgrade tends towards stability. Calculated result shows that after 20 years, the permafrost tables under the two-side vertical and inclined type thermosyphon subgrades are 2.88 and 1.88 m respectively, the permafrost tables under one-side vertical and inclined type thermosyphon subgrades are 3.84 and 3.46 m, respectively, so, the two-side type thermosyphon subgrade expresses a stronger long-term cooling effect than the one-side type thermosyphon subgrade, similarly, the inclined type thermosyphon subgrade has a stronger cooling effect than the vertical type thermosyphon subgrade. The annual average power of one thermosyphon varies from 47 W to 56 W, agreeing well with the monitoring data. 5 tabs, 31 figs, 30 refs.

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Last Update: 2016-08-30