Investigation of Frost Heave Considering the Boundary Conditions of Artificial Ground Freezing

Abstract

The construction of traffic routes in the subsoil is increasingly been carried out by artificial ground freezing. Due to artificial heat removal, a load-bearing frost body arises, which becomes water-impermeable in its closed form. However, frost heave at the ground surface may lead to damage buildings. In fine-grained soils, the frost heave is caused by the 9% volume expansion of the pore water during freezing and, in particular, by the formation of ice lenses. For the formation of ice lenses, water from unfrozen zones is suctioned to the frost line and freezes to continuous ice lenses. Based on horizontal freezing pipes in the subsoil, the decisive heaves at the ground surface result from the frost penetration direction to the ground surface and in the opposite direction. In this case, the ice lenses grow parallel to the ground surface. In order to investigate the frost heave due to ground freezing boundary conditions, a test device was designed to carry out one-dimensional frost heave tests taking into account the upward and downward freezing directions.