Field Investigation of Soil Heave by a Large Diameter Chilled Gas Pipeline Experiment, Fairbanks, Alaska |
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Authors: | Scott L Huang Matthew T Bray Satoshi Akagawa Masami Fukuda |
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Affiliation: | 1Professor, Dept. of Mining and Geological Engineering, Univ. of Alaska Fairbanks, P.O. Box 755800, Fairbanks, AK?99775-5800. 2Graduate Student, Dept. of Civil and Environmental Engineering, Univ. of Alaska Fairbanks, P.O. Box 755900, Fairbanks, AK?99775-5900. 3Professor, Graduate School of Engineering, Hokkaido Univ., Sapporo, Hokkaido, Japan?060-8628. 4Professor, Institute of Low Temperature Sciences, Hokkaido Univ., Sapporo, Hokkaido, Japan?060-8628.
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Abstract: | A large scale 105-m-long, 0.9-m-diam chilled pipeline experiment was conducted to assess the response of a production pipeline that transits between unfrozen (seasonally frozen) and permafrost soils in discontinuous permafrost regions. Thermal and heave characteristics of the experiment for a three-year monitoring period are reported. In response to the chilled pipeline, the progressive cooling patterns within the permafrost and unfrozen soils were different, resulting in the development of a thermal boundary at the transition zone between the two thermally different soils. The absolute maximum movement of pipeline was 0.197 m near the thermal boundary, resulting in a differential heave of 0.148 m. Three distinct heave phases were identified within the unfrozen soil. Phase 1 of the first 200 days related to penetration and heave above the groundwater table and was characterized by heave rates between 0.211 and 0.237 mm/day. Phase 2 resulted in increased ice segregation due to interaction of the freez-ing front with the groundwater table. This phase lasted from approximately day200 to day 500 and corresponded to a heave rate from 0.206 to 0.313 mm/day. Phase 3 was characterized by a further decrease in the heave rate to about 0.081 mm/day and lasted from approximately day 500 to day 1,056. |
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Keywords: | Field investigations Alaska Gas pipelines Permafrost Cold regions Differential settlement |
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