Study on thaw consolidation of permafrost under roadway embankment

In order to analyze thaw consolidation of permafrost beneath roadway embankment, the concept of the effective consolidation time is established. A 3-D large strain thaw consolidation model based on Eulerian description is presented and applied to analyze consolidation behaviors of thawed permafrost layer under embankments of the Qinghai-Tibet highway. It is found that thaw consolidation is controlled by several factors, including load, the effective consolidation time as well as the characteristic drainage length. Combination of these factors makes the effect that in the initial operation years of the highway, degree of thaw consolidation increases. After a certain number of years, it decreases mainly due to the increase in the characteristic drainage length and decrease in the effective consolidation time. Pore water then accumulates in the post-thawed domain, which would take some residual consolidation time to dissipate. This explains the phenomenon that in some permafrost areas on the Qinghai-Tibet plateau permafrost has already completely thawed, while settlement of roadway embankment continuously develops.