Golmud-Lhasa Railway Geological Survey


Updated :07,12,2012

The Golmud-Lhasa Railway across the Tibetan Plateau faces hazards of permafrost deformation, active faulting, earthquakes and other types. The China Geological Survey (CGS) together with the Railway Ministry of China deployed active fault mapping, geological hazard survey and stress measurements along the Golmud-Lhasa Railway during 2001-2003. This provided the necessary geological data for designing railway construction and mitigating geological hazards in addition to the considerable drilling and large-scale engineering geological survey along the railway-line organized by Railway Ministry of China in 2001.

The Quaternary geological survey mapped the Kunlun Mts., Tanggula Mts., Nyainqentanglha Mts. Chumaerhe River, Tuotuohe River, Naqu River and Namco Lake at a scale of 1:100 000 and dated glacial, lacustrine, fluvial and alluvial deposits, and established new time constrains for active faults along the Golmud-Lhasa Railway. New evidence on Quaternary environment changes in the central Tibetan Plateau, especially glaciation and lake level changes were discovered.

ETM remote sensing images, geophysical prospecting, trenching and field mapping at scale of 1:2000 were used to survey active faults along the Golmud-Lhasa Railway. This identified and marked 114 active faults for railway design, including 4 intensive active faults, 28 regional active faults and other minor active faults. Geological hazards posed by active faulting in the permafrost areas include surface rupture and deformation from earthquake, fault creep, thaw depression, freezing expansion and fracture zones. These were measured in detail.

It is estimated that the Xidatan active fault has a sinistral strike-slip movement with an average rate of 7.7mm/a in Holocene, the Hohxil active fault has sinistral strike-slip rates of 3.3-7.8mm/a in Holocene, and the Bengco active fault has an average dextrally strike-slip rate of 11.5mm/a in Late Pleistocene-Holocene. Major boundary faults of the Wenquan, Ando, Gulu-Sangxiong and Yangbajain-Damxung grabens experience vertical slip rate of 0.45-1.2mm/a, 0.3-0.5mm/a, 0.8-1.4mm/a and 1.1-2.0mm/a respectively in Late Quaternary, which corresponds to the evident crustal extension of central Tibetan Plateau. Evidence for more than 3-4 intensive palaeo-earthquakes in Late Pleistocene-Holocene are present along the Xidatan, Hohxil and Bengco strike-slip faults and major boundary faults of the Wenquan, Gulu-Sangxiong and Yangbajain-Damxung grabens.

Migrating pingos were discovered in Budongquan valley, Chumaerhe River, South Yamaerhe River and the 83rd station, 85th station and 86th station along the Golmud-Lhasa Railway. Pingos form along active faults in permafrost northern Tibetan Plateau, and many change position annually along active fault zones and thus appear to migrate. Migrating pingos have damaged the highway and the oil pipeline adjacent to the railway since 2001. One caused tilting and breaking of a bridge pier and destroyed a highway bridge across the Chumaerhe River. The potential hazards of migrating pingos to railway bridges were discovered at the 83rd and 85th stations of the highway.

In-situ stress measurements were carried out in surrounding areas of the Kunlunshan,Fenghuoshan and Yangbajain tunnels of the Golmud-Lhasa Railway by the overcoring piezomagnetic method. This provided important data for tunnel design. Stress change before and after the Ms 8.1 Kunlun Earthquake was measured north of the Xidatan active fault. Stress before the earthquake reached to as high as 6-12MPa, and dropped to as low as 2-3MPa 6 months after the earthquake, giving constrain for modeling and precursor for prediction of intensive earthquakes.

Stress fields for tunnels with different geometric shapes were calculated by finite element modeling. Laboratory testing for mechanical properties of rocks and assessments on tunnel stability and crustal stability were carried out for the Golmud-Lhasa Railway. These were then used to make suggestions for strengthening engineered facilities and decreasing the geological hazards.