Soil moisture, ground temperatures, and deformation of a high-speed railway embankment in Northeast China

Abstract

Embankment deformation is a key consideration in high speed railway construction. Frost heave due to temperature and moisture variation is critical to consider in areas of seasonally frozen ground. This paper examined ground temperatures, frost heave, and moisture content in 2013–2014 at two sites along the embankment of the Harbin-Dalian Passenger Dedicated Line (HDPDL) railway. The railway is in seasonally-frozen ground of Jilin Province, China. The embankment at one site (K977) was built on the undisturbed ground surface while the other was in a cut section (K1004). Displacement measurements over one year indicated that frost heave of 14mm at K977 and 25mm at K1004 occurred in ballast during the freezing season. During the annual freeze-thaw period, soil moisture content varied drastically in the upper 0.6m. The frost depth and freezing index were strongly and positively correlated during the freezing season. Soil moisture content was regarded as the primary control on the amount of frost heave, while frost depth was secondary. Furthermore, water vapor diffusion may have been an important contributor to the formation of near-surface ice. At K1004 site, the maximum recorded deformation was large and exceeded the 15mm Chinese standard for maximum allowable heave. This suggested that high ground water level increased the amount of frost heave.