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Study on the Distribution Pattern of Temperature Fields and Anti-freezing and Heat Preservation of Ventilation Shafts in High-altitude and Cold Regions
(1. China Railway Tunnel Group No. 2 Engineering Co., Ltd., Langfang 065000; 2. School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031; 3. Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031)
Abstract Based on the ventilation shafts in the Dongliangdi Tunnel, on-site monitoring was conducted for the tem? perature field during the construction of ventilation shafts in a high-altitude and cold region, and the method of CFD simulation calculation was used to analyze the temperature field during the operation and to research the distribution pattern of the temperature field of shafts under different ventilation conditions and the cold-proof and thermal insulation measures. The analysis results showed that the impact of low ambient temperature on shafts during construction was relatively small due to the warm return air at the bottom of shafts, and when the return air at the bottom of shafts was beneficial to anti-freezing of shafts, exhaust shafts would also not be frozen during the operation. The surrounding rocks behind the whole blowing-in shaft were frozen to different degrees during operation and ventilation in winter, and the depth of frost was greatly affected by the time of ventilation and less affected by the velocity of wind, and the development of depth of frost became stable after 2 months of ventilation; the construction of insula? tion layers could reduce the changes in the temperature of surrounding rocks during operation, and after comprehensively considering various factors, it is recommended to pave a 6 cm-thick polyurethane insulation layer on the blowing-in shaft side of the projec.
Abstract：
Based on the ventilation shafts in the Dongliangdi Tunnel, on-site monitoring was conducted for the tem? perature field during the construction of ventilation shafts in a high-altitude and cold region, and the method of CFD simulation calculation was used to analyze the temperature field during the operation and to research the distribution pattern of the temperature field of shafts under different ventilation conditions and the cold-proof and thermal insulation measures. The analysis results showed that the impact of low ambient temperature on shafts during construction was relatively small due to the warm return air at the bottom of shafts, and when the return air at the bottom of shafts was beneficial to anti-freezing of shafts, exhaust shafts would also not be frozen during the operation. The surrounding rocks behind the whole blowing-in shaft were frozen to different degrees during operation and ventilation in winter, and the depth of frost was greatly affected by the time of ventilation and less affected by the velocity of wind, and the development of depth of frost became stable after 2 months of ventilation; the construction of insula? tion layers could reduce the changes in the temperature of surrounding rocks during operation, and after comprehensively considering various factors, it is recommended to pave a 6 cm-thick polyurethane insulation layer on the blowing-in shaft side of the projec.
WANG Jianjun1 YANG Linlin2,
3 YANG Wenbo2,
3 ZHANG Yifei2 etc
.Study on the Distribution Pattern of Temperature Fields and Anti-freezing and Heat Preservation of Ventilation Shafts in High-altitude and Cold Regions[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(4): 118-126
2022, Vol. 59 