A Hypoplasticity-Based Method for Estimating Thaw Consolidation of Frozen Sand

Abstract

Thaw consolidation of frozen ground is one of the main causes for settlement of foundations in cold regions engineering. This paper firstly derived an improved von Wolffersdorff hypoplastic model by incorporating an internal state variable S to represent the cohesive forces of frozen soils. Then the principle of effective stress was enhanced by introducing a new expression of the Bishop Factor based on the water retention curves of fine sand. As for the migration of water during thaw consolidation, a modified Richards' equation was used for porous fluid flow in a saturated or partially saturated soil. Coupled with the heat transfer equation taking into account the ice-water phase change, a numerical method was proposed for analyzing the thermo-hydro-mechanical processes during thaw consolidation of frozen ground. It was numerically implemented in the FISH language on the FLAC platform and was verified by thaw consolidation tests on frozen fine sand samples in laboratory. Results indicate that the calculated results agree in general with test data.