A simplified numerical method to simulate the thawing of frozen soil

Thawing weakens the frozen soil supporting buildings and lifelines from Siberia to Alaska, resulting in settlements up to hundreds of millimetres during a single season. This paper presents a simplified sequentially coupled numerical approach that can be implemented in a general purpose, commercially available finite-element analysis model. It is intended to provide a reasonably accurate computational tool for the analysis of structures on degrading permafrost, allowing modelling of complex three-dimensional geometries and boundary and loading conditions. The method permits simulation of the temperature-dependent thermal and mechanical properties of soils in an approximate manner. It accommodates large-strain consolidation theory, also allowing use of plasticity constitutive relationships. A thorough validation study was carried out involving comparison with monotonic and cyclic thaw consolidation element tests, analytical solutions and a well-documented case study of an unstable roadway embankment. The latter was complemented by an investigation of thaw-settlement remediation solutions using thermosyphons, with emphasis on the three-dimensional response and their transverse spacing.