Engineering Corridor Research Articles

Thaw-induced slope failures and susceptibility mapping in permafrost regions of the Qinghai–Tibet Engineering Corridor, China

With recent climatic warming and enhanced human activities, slope failures related to permafrost degradation are widespread along the Qinghai–Tibet Engineering Corridor. Assessment and mapping of the slope failures are necessary to mitigate hazards and plan engineering activities. According to our field investigations, the occurrence of slope failures is mainly controlled by the slope gradient, ground-ice content, permafrost temperatures, surficial deposits, and slope aspect. Modeling conducted in ArcGIS™ was used to produce a slope failure susceptibility map for a representative region along the Qinghai–Tibet Railway from Wudaoliang to Fenghuo Mountain Pass. The study region was divided into four classes based on slope failure susceptibility: (1) unlikely, (2) low, (3) moderate, and (4) high. Areas classified as unlikely accounted for 10.76 % of the study region, while low susceptibility areas comprised 44.51 %. The moderate and high susceptibility zones comprised 21.79 and 22.94 %, respectively. The actual distribution of slope failures in the region was consistent with the modeled results, which demonstrates the utility of the assessment method for future hazard management and engineering planning.

Permafrost and cold-region environmental problems of the oil product pipeline from Golmud to Lhasa on the Qinghai–Tibet Plateau and their mitigation

Abstract The 1076-km-long Golmud–Lhasa oil product pipeline is located closely parallel to the highway constructed 20 years earlier within the relatively narrow north–south engineering corridor crossing the treeless central area of the Qinghai–Tibet Plateau. Much of the corridor is at elevations exceeding 4500 m and high-elevation, generally warm permafrost is encountered in more than one-half of the length. The pipeline, transporting mostly diesel, motor and aviation fuels at ambient temperatures, is 159 mm in diameter, has a wall thickness of 6 mm and was buried in a trench at a nominal depth of between 1.2 and 1.4 m. The soils encountered, mostly periglacial sands, silts and gravels, often have elevated saline contents and are subject to severe wind erosion and occasional monsoon flash flooding conditions. During its first quarter century of operation, the pipeline suffered at least 30 significant leaks and four pipeline ruptures. About 337 km of the pipeline was extensively rehabilitated, including relocations or replacements in major problem areas and, where feasible for an existing pipeline, improvements in pipeline protection during 2001–2004. It was supposed to safely operate for another 30 years with proper checks and needed repairs. This paper provides a review on the history of the permafrost and cold regions environmental problems of the pipeline, and their major rehabilitation, repairs and problems in the future, which might have useful implications for similar oil product pipeline at high elevations or permafrost regions.

Changes in permafrost environments along the Qinghai–Tibet engineering corridor induced by anthropogenic activities and climate warming

The sensitive permafrost environments along the Qinghai–Tibet Engineering Corridor (QTEC) from Golmud to Lhasa are controlled by periglacial processes, geography, geocryology and the local climate. During the past 50 years, permafrost has been degrading at a rapid rate due to the combined influences of steadily increasing human activities and persistent climatic warming, and extensive accelerated degradation has been observed along the QTEC. In many locations, the surface vegetation and the top soils have been completely removed, or destroyed, and have led to significantly increased water and soil erosion, with extensive and serious environmental and engineering impacts. The vegetation along the QTEC is dominated by alpine grasslands and meadows. The alpine grasslands have a better capability for recovery from the damages than the meadows. At sections where the vegetation and soils were severely damaged, it will take 20–30 years for alpine grasslands to recover their ecological structures and biodiversity similar to that of the original conditions, whereas it will take 45–60 years for the alpine meadows. The environmental management and protection along the QTEC are urgent and important for the long-term stability of engineering foundations, and for the sustainable development on the Qinghai–Tibet Plateau (QTP). The proper protection and management requires the development of a non-interference plan and acceleration in the enactment and enforcement of environmental protection (laws, regulations and stipulations) based on an extensive and thorough understanding and practical rehabilitation techniques for disturbed or damaged permafrost environments.