Geotechnical conditions of in-field road design in northern territories of Yamalo-Nenets Autonomous Okrug (Tomsk)

The Yamal-Nenets Autonomous District is the largest hydrocarbon resource base, supplying up to 300–330 billion m3/year of gas and up to 10–15 million t/year of liquid hydrocarbons. Mineral extraction is accompanied by the development of engineering infrastructure, namely: cluster pads, oil storage tanks, pumping stations and automobile roads that link both within and between sites. The area is unique in terms of complexity of geotechnical conditions due to permafrost soils in particular in the upper open-cast. The assessment of geotechnical conditions of the field development as well as adverse processes, hazards, risks and impacts on designed, constructed and operating roads to the cluster pads is undoubtedly relevant.

Purpose: The evaluation of geotechnical conditions of design, construction and operation of in-field roads in the Severo-Komsomolsk field.

Methodology/approach: The analysis and generalisation of materials of geotechnical surveys for design and construction documentation of the cluster pad 11 in the Severo-Komsomolsk oilfield, performed by AO "TomskNIPIneft". Determination of composition and physical properties of undisturbed soils taken when equipping observation posts, performed in the Laboratory of Ground Science and Soil Engineering, TSUAB.

Research findings: Natural and geotechnical conditions of the Yamal-Nenets Autonomous District includes areas with hard frozen soil and areas with complete or partial absence of permafrost soils. In the first case, the subgrade design envisages that the upper permafrost horizon is not lower than the embankment bottom and remains at this level during the entire period of the road operation. In the second case, the design implies preliminary thawing of frozen soil lenses and road drainage prior to the subgrade construction. In the first case, the position of perennially frozen soils is evaluated by the appropriate embankment height, when non-cemented road-building materials are used, and by arranging heat-insulating layers (peat, polystyrene foam, hard frozen soil) with their thermotechnical calculation. The first principle implies the subgrade construction only in winter. To prevent deformation of embankment slopes, it is recommended to build peat benches fixed with a geosynthetic material. Land reclamation in the road construction zone should be avoided to prevent erosion of the soil cover.

1. Yamal geography Available: https://yanao.ru/region/obshchie-svedeniya/#geography (accessed October 24. 2023). (In Russian)

2. SP 34.13330.2021. Automobile roads. Moscow: Minstroi Rossii, 2021. 151 p. (In Russian)

3. The Yamal-Nenets Autonomous District. Available: https://znanierussia.ru/articles/ (accessed October 24, 2023). (In Russian)

4. Development of cluster pad 11 in the Severo-Komsomolsk field: Technical report. AO “TomskNIPIneft'”. Tomsk, 2018. 258 p. (In Russian)

5. Kudryavtsev V.A. (Ed.) Basics of permafrost prediction in geotechnical studies. Moscow: MSU, 1989. 143 p. (In Russian)

6. Geophysical methods in cryogenic territory investigation. Moscow: MSU, 2007. 272 p. (In Russian)

7. Ershov E.D., et al. (Eds.) Geocryology of the USSR. Western Siberia. Moscow: Nedra, 1989. 454 p. (In Russian)

8. SP 34.13330.2021. Code specification. Motorways. Moscow: Minstroi Rossii, 2021. 151 p. (In Russian)

9. SP 115.13330.2016. Code specification. Geophysics of natural hazards. Moscow: Minstroi Rossii, 2016. 36 p. (In Russian)

10. SP 25.13330.2020. Foundations and footings on permafrost soils. Moscow: Minstroi Rossii, 2022. 153 p. (In Russian)

11. SP 86.13330.2022. SNiP III-42–80* Main pipelines. Moscow: Minstroi Rossii, 2022. 147 p. (In Russian)

12. SP 313.1325800.2017. Automobile roads in permafrost areas. Design and construction rules. Moscow: Minstroi, 2017. 133 p. (In Russian)

13. CP 131.13330.2020. Code specification. Construction climatology. Moscow: Minregion Rossii, 2021. 116 p. (In Russian)

14. Methodological recommendations for design and construction of earthwork in permafrost zone using loosened permafrost soils in permafrost state during operation (for experimental construction). Moscow: Mintrans Rossii, 2003. 31 p. (In Russian)

15. GOST 10354–82. Polythene film. Moscow: Standartinform, 2007. 82 p. (In Russian)

16. Ashpiz E.S., Khrustalev L.N., Vedernikova M.A., Emel'yanova L.V. Synthetic thermal insulators for railway embankments in permafrost conditions. Kriosfera Zemli. 2008; 12 (2): 84–89. (In Russian)

17. Temperature analysis of permafrost soils of bridge piers bases on road 15 and bridges of the Obskaya–Bovanenkovo railway line. Stage 1. Cooling effect of thermal supports. Moscow, 2010. (In Russian)