Frost Heaving Characteristics of Subgrade Soils Using Laboratory Freezing System

摘要

The influence of fines of the frost susceptibility of subgrade soils were established by laboratory freezing system tests simulating closely the thermal conditions in the field. During the winter season, the climate is heavily influenced by the cold and dry continental high pressure. Because of Siberian air mass, the temperature ofJanuary is -6 ～ -7°C on average. This chilly weather generates the frost heaving by freezing the moisture of soil and potential damage of the road structure. In the freezing soil, the ice lenses increase the freezing portion of soil by absorbing the ground water with capillary action. However, the capillary characteristics differ from the sort of soil on the state of freezing condition. In the current design codes for anti-freezing layer, the thickness of anti freezing layer is calculated by freezing depth against the temperature condition. Therefore, they have a tendency of over-design and uniform thickness without the considerations of thermal stability, bearing capacity and frost susceptibility of materials. So, it is essential for studying the appropriateness and bearing capacity besides the seasonal and mechanical properties of pavement materials to take a appropriate and reasonable design of the road structure. In this research, the evaluation of frost susceptibility was conducted by means of the physical property test and laboratory freezing system apparatus. The temperature, heaving amount, heaving pressure and unfrozen water contents of soil samples for the subgrade soils of highway construction site, were measured by using the laboratory freezing system to determine the frost susceptibility.