Abstract: In order to study the law of thaw consolidation for high ice content permafrost embankment, a nonlinear constitutive relationship was incorporated into the original linear large strain thaw consolidation theory and a piecewise interpolation function was used to implement the nonlinear relationship between compression modulus and void ratio. Numerical simulation method of thaw consolidation was further modified. Validity of this work was verified by the monitored data of Qinghai-Tibet highway. The analysis results shown that the thaw consolidation calculation accuracy of high ice content embankment can be notably improved by the modified thaw consolidation theory and numerical simulation method. Further analysis indicated that the interactive effects between thermal and mechanical field can be further reasonably described by the nonlinear stress-strain relationship. The thawing consolidation degree of frozen soil is affected by effective thawing consolidation time and characteristic drainage length, which is completely different from the development law of thawing roadbed. The thaw consolidation degree increases in the early stage of roadbed operation, while with the development of time, the degree of consolidation decreases continuously after reaching the peak value. This is mainly due to the increase of characteristic drainage length and the shortening of effective melting and consolidation time caused by the continuous increase of melting depth. Therefore, the nonlinear constitutive relationship must be employed to calculate the stability design parameters, such as thaw depth, settlement and consolidation degree when the high ice content permafrost embankment was involved.

Key words: frozen soil, thaw consolidation law, nonlinear constitutive mode, numerical simulation