Advances in Earth Science ›› 2021, Vol. 36 ›› Issue (1): 69-82. doi: 10.11867/j.issn.1001-8166.2021.010
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Xinze LI 1 , 2 , 3( ), Huijun JIN 4( ), Qingbai WU 1, Yanjing WEI 5, Zhi WEN 1
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Xinze LI, Huijun JIN, Qingbai WU, Yanjing WEI, Zhi WEN. Numerical Analysis of Temperature Field Around Buried Gas Pipeline in Arctic Permafrost Regions[J]. Advances in Earth Science, 2021, 36(1): 69-82.
Based on one planned arctic gas pipeline project which will cross continuous, discontinuous and sporadic permafrost zones and zones of seasonal frost from north to south, with 5 ℃, -1 ℃ and -5 ℃ settings of gas-flow in buried pipeline, a geothermal model for the interactions between pipeline and permafrost was established to investigate the thermal effect of pipelines on the freezing and thawing of soil around pipeline and thermal stability of permafrost by using a commercially available finite-element program for numerical analysis. The results show that different pipeline gas flow temperatures influence the permafrost table greatly. Especially in discontinuous permafrost zones the permafrost table is influenced in both positive temperature and negative temperature. The warm (+5 ℃) gas pipeline could lower permafrost table by about 1 to 3 times of pipe diameter and aggravate the degradation of permafrost around pipeline; The cold (-1 ℃) and chilled (-5 ℃) gas pipeline can effectively raise the permafrost table and maintain the thermal stability of frozen soil, but the temperature of soils under the chilled (-5 ℃) pipeline decreases obviously, which may lead to frost heave hazards. In terms of thermal stability around pipeline, it is advised that a transporting temperature of gas flow as -1 ℃ should be adopted in continuous permafrost zone all year round which causes only little disturbance to the permafrost environment; in discontinuous permafrost zone pipeline could operate above freezing in the summer months with the station discharge temperature trending the ambient air temperature, but the discharge temperature must be maintained as -1 ℃ throughout the winter months; in zone of seasonal frost the cold (-1 ℃) and chilled (-5 ℃) pipeline may cause frost heave, therefore pipeline should run in positive temperature without extra temperature cooling control. Finally, the initial framework solutions are proposed in hope of supplementing existing gas transporting process theory and identifying new approaches for gas pipeline in northern and upland permafrost regions.