In cold regions, frost heave and thaw settlement are the two uppermost hazards generally causing significant damages during engineering construction and operation. Segregation ice formation is the essential factor resulting in frost heave and thaw settlement deformations. Investigations of ice-water pressure variations are the main contents and means to reveal the ice segregation process. In the current project, the ice-water pressures of silty clay along Qinghai–Tibet railway will be measured during the soil freezing under different boundary conditions and soil samples status. Temperature, water intake, water content, pore water pressure, matrix potential and the surface displacement will also be measured; meantime, the location, thickness and interval of segregation ice will be recorded by visualization technique. The ice-water pressure change rules and its affecting factors can be determined through comparative experimental study. Base on the ice-water pressure changes, the ice segregation process can be first determined, and then the generalized force of water migration can be obtained, finally the generalized Clausius–Clapeyron equation can be developed. This project is expect to provide theoretical basis for accurately predicting frost heave and thaw settlement deformations by focusing on ice-water pressure changes and ice segregation process.