Investigation of permafrost engineering geological environment with electrical resistivity tomography: A case study along the China-Russia crude oil pipelines

• Published in: Engineering geology 2021-09, Vol.291, p.106237, Article 106237
• Main Authors: Li, Xinyu, Jin, Xiaoying, Wang, Xinbin, Jin, Huijun, Tang, Liang, Li, Xiaoying, He, Ruixia, Li, Yan, Huang, Canjie, Zhang, Sifan
• Format: Article
• Language: English
• Subjects: Changing engineering geological environment; China-Russia Crude Oil Pipelines; Climate warming; Discontinuous permafrost zones; Electrical resistivity tomography
• ISSN: 0013-7952; 1872-6917
• DOI: 10.1016/j.enggeo.2021.106237

The electrical resistivity tomography and vegetation surveys were conducted for investigating the distribution of frozen ground and other engineering geological characteristics at four representative sites (BHP, XFB, WLG, and XAZ) along the China-Russia Crude Oil Pipelines (CRCOPs) I and II. The comprehensive analysis shows that CRCOPs play an important role in forming and connecting supra-permafrost subaerial taliks and in facilitating thermokarst landforms, further accelerating permafrost degradation. The survey results indicate that on 15–29 August 2019, the permafrost base under the CRCOP at the XFB site was 21.5 m in depth, that of WLG site was 21.5 m (32.8 m at the undisturbed sites), and that of XAZ site, 37.3 m; the permafrost table of XFB site was 6.72 m (4.97 m on 20 m away from the pipeline), that of WLG site was 8.64 m (1.94 m at the undisturbed sites), and that of XAZ site was 6.72 and 3.38 m on the southern and northern slopes; the hydrothermal influences of CRCOPs extended horizontally to about 60 m away from the pipelines, but the vertical hydrothermal impacts were largely limited to about 10–15 m in depth at the BHP site in the zone of deep (>1.5 m) seasonal frost. The extent of engineering influences from the pipelines and associated engineering activities in patchy and island permafrost are evidently larger than those in seasonal frost. The sites with substantial changes are found in pipeline foundation soils underlain by warm (> − 1 °C; thermally unstable) and ice-rich permafrost. This study can timely help decision makers mitigate frost hazards in a proactive manner. •The ERT survey revealed several connecting supra-permafrost subaerial taliks between the CRCOPs I and II.•The permafrost table at WLG is 8.64 m under the CRCOPs, but 1.94 m at the undisturbed sites.•The permafrost base at WLG is 21.5 m under the CRCOPs, but 32.8 m at the undisturbed sites.•Hydrothermal influences of CRCOPs reached 10–15 m in depth and 60 m horizontally after 2–9 years of operation.