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Railway subgrade, permafrost, subgrade settlement and lateral spreads, soil freezing, retaining structures

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«Earth`s Cryosphere», 2017, Vol. XXI, № 4, p. 36-47

Deformation of railway subgrade upon permafrost and stabilization measures

P.I. Dydyshko

Stock Company “Railway Transport Research Institute”,
10, 3rd Mityschinskaya str., Moscow, 129626, Russia; otdputi@mail.ru

The paper presents results of experimental studies of subgrade deformation in permafrost areas and measures for its stabilization. Deformation results from heat transfer changes caused by railway construction and operation. An embankment loads the cryotic soil like a hot press which lowers the permafrost table to 6–10 m below the superstructure and causes melting of ground ice. The subsequent extrusion of thawed yielding muddy soil from beneath the subgrade leads to decades-long soil subsidence. As a result, the subgrade experiences settlement and lateral spreads, especially in poorly drained soils with a moss-grass-peat cover. As shown by experiments, native soil under the subgrade is mechanically weak and prone to rheological changes (plastic flow) that induce uneven subgrade settlement. Moisture migration in thawing soil is driven by thermo-electrokinetic forces in thermally anisotropic capillary systems. Possible subgrade stabilization measures include ground freezing under slopes and creating mechanical barriers to soil extrusion. A number of respective engineering solutions have been suggested and experimentally tested.

Railway subgrade, permafrost, subgrade settlement and lateral spreads, soil freezing, retaining structures

DOI: 10.21782/EC2541-9994-2017-4(36-47)

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