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Research on the Influence of Sprayed Concrete on the Surrounding Rock Freeze-Thaw Circle of Highway Tunnels in Permafrost Regions
(1 Department of Geotechnical Engineering, Tongji University, Shanghai 200092; 2 College of Construction Engineering, Jilin University, Changchun 130026; 3 Electric Power Design and Research Institute of Guangdong Province, Guangzhou 510663; 4 CCCC First Highway Consultants Co. Ltd., Xi'an 710075)
Abstract During tunnel construction in permafrost regions, control of the temperature field and freeze-thaw circle of the surrounding rock is the key factor for ensuring the stability of the surrounding rock and the security of the structure. In this paper, a two-dimensional unsteady temperature field model for the heat transfer of surrounding rock in light of the hydration heat of concrete is established. Based on this, the changing rules of the temperature field of the surrounding rock before and after concrete spraying are analyzed, as well as the influence of construction time and thickness of the sprayed concrete on the freeze-thaw circle of the surrounding rock. A contrastive analysis between calculated results and measured results is performed. Research results show that: the calculated data generally agrees with the measured data, with a temperature error of no more than 0.5℃ for the rock at 0.5m away from the tunnel sidewall; before sprayed concrete construction, the temperatures of the surrounding rock at different depths are slow to grow; after sprayed concrete construction, the temperature of the surrounding rock within a depth of 1m rises sharply at first, then declines, and later tends towards stabilization because of the hydration heat of concrete; furthermore, when the sprayed concrete construction is delayed 1 day or its thickness increases every 5cm, the depth of the freeze-thaw circle increases about 10cm.
Abstract：
During tunnel construction in permafrost regions, control of the temperature field and freeze-thaw circle of the surrounding rock is the key factor for ensuring the stability of the surrounding rock and the security of the structure. In this paper, a two-dimensional unsteady temperature field model for the heat transfer of surrounding rock in light of the hydration heat of concrete is established. Based on this, the changing rules of the temperature field of the surrounding rock before and after concrete spraying are analyzed, as well as the influence of construction time and thickness of the sprayed concrete on the freeze-thaw circle of the surrounding rock. A contrastive analysis between calculated results and measured results is performed. Research results show that: the calculated data generally agrees with the measured data, with a temperature error of no more than 0.5℃ for the rock at 0.5m away from the tunnel sidewall; before sprayed concrete construction, the temperatures of the surrounding rock at different depths are slow to grow; after sprayed concrete construction, the temperature of the surrounding rock within a depth of 1m rises sharply at first, then declines, and later tends towards stabilization because of the hydration heat of concrete; furthermore, when the sprayed concrete construction is delayed 1 day or its thickness increases every 5cm, the depth of the freeze-thaw circle increases about 10cm.
SHEN Shi-Wei-1,
2 ,
XIA Cai-Chu-1 etc
.Research on the Influence of Sprayed Concrete on the Surrounding Rock Freeze-Thaw Circle of Highway Tunnels in Permafrost Regions[J] MODERN TUNNELLING TECHNOLOGY, 2015,V52(1): 82-88
2015, Vol. 52 