Permafrost

Assessment of Frozen Soils Environmental Geological Conditions along
the Qinghai-Tibet Engineering Corridor from Xidatan, Qinghai to
Nagqu, Tibet, China
Hui-jun Jin, Shao-ling Wang
(State Key Laboratory of Frozen Soils Engineering, Cold and Arid Regions Environmental and Engineering
Research Institute, Chinese Academy of Sciences, Lanzhou, China 730000; Email: hjjin@lzb.ac.cn)
Abstract: The Qinghai-Tibet Engineering Corridor (QTEC) traverses 670 km of permafrost
and seasonally frozen ground from Xidatan in the north to Nagqu in the south in the interior of
the Qinghai-Tibet Plateau (QTP). The QTEC lies in a belt of several hundred of meters to
several kilometers in width that is sensitive to natural and engineering disturbances and in the
cold regions ecotones susceptible to climatic and environmental changes. The major
engineering infrastructures within the QTEC include the Qinghai-Tibet Highway (QTH),
Qinghai-Tibet Railway (QTR), Golmud to Lhasa Ambient Temperature Product Oils Pipeline
(GLATPOP), Lanzhou-Xi’ning-Lhasa Fiber-Optic Cables (LXLFOC), and 110kV Power
Transmissions Line (110kVPTL), and associated maintenance stations/squads. These
engineering structures and frozen ground eco-environments intensively interact each other,
resulting in constant environmental changes. Along the QTEC, there are large expanse of
continuous permafrost, and significant amount of island-sporadic permafrost in the middle
section, and deep seasonally frozen ground on the northern and southern edges and along or at
the large river valleys. The QTEC is characterized by high elevations, arid, cold and windy
climate, active tectonics, and resultant distinct conditions in frozen ground environmental
engineering geology. High elevations, relatively low latitudes, and distinct division of large
geomorphological units control the regional distribution of frozen ground and ground ice.
However, local differentiations in frozen ground environmental engineering geology occur due
to the variations and their changes in soils and lithology, water and ice contents, thicknesses of
the active layer, ground temperatures, surface vegetation, and periglacial hazards. Three
engineering geology zones, 20 engineering geology subzones, and 51 engineering geology
sections are divided based on the regionalization at three levels. The division in engineering
geological conditions at the first level takes account of regional distribution of various frozen
ground types and resultant differences in frozen ground engineering geology, resulting in three
categories of frozen ground zones: large expanse of continuous permafrost, island-sporadic
permafrost, and deep seasonally frozen ground. Based on the division of the three zones, the
subdivisions at the second level reflect the thermal stability characterized by mean annual
ground temperatures and other basic features of frozen ground. The next level divisions,
engineering geology sections, which are the most basic units in frozen ground engineering
geology, are mainly based on the ground ice contents and aim at reflecting present conditions in
frozen ground engineering geology and cold regions ecological environments. Each zones,
subzones and sections are concisely evaluated for engineering design and hazards mitigation.
Key words: Qinghai-Tibet Engineering Corridor (QTEC), frozen ground environmental
engineering geology (FGEEG), assessment, mean annual ground temperatures (MAGTs),
ground ice contents (GICs).
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