Study Of Application Of XPS Board In Frozen Subgrade Works

The Daxinganling region is one of the major frozen earth areas all year long in China. Since the operation of railways in this region, different defects have arisen in the works of subgrade. Take the subgrade settlement and freezing and expansion for example, the defects occupy 60-70%. So, it is meaningful for the design and construction in the many year frozen area by carrying out a research into the application of polystyrene extrusion insulation boards (XPS). It is also helpful for the construction and maintenance of Golmud-Lhasa section on the Qinghai-Tibet Railway.In the present work, the Yakeshi-Linhai railway was taken into account to analyze the characteristics of freezing and expansion in the many-year frozen subgrade. The ground base earth and the particles of the subgrade fillers as well as the frozen and melted tests were investigated. It was proposed that an insulation layer consisting of insulation boards and subgrade fillers was necessary for improving the maximum limit of the frozen earth. A temperature sensor was observed periodically to record the movement regulation of the maximum of the frozen earth, the temperature gradient of the ground near the insulation material, and the distribution law of the temperature gradient in the interior of the subgrade. A settlement board, a water level pile indicator, and a magnetic ring settlement gauge were employed to investigate the frozen and melted deformation regulation of the subgrade and the ground base. A neutron gauge was adopted to measure the moisture change on the up and down surface of the insulation materials. Graphs and tables were listed to analyze the variations of the properties of XPS and polystyrene foam insulation boards (EPS) when they were used in compression, thermal insulation, waterproof, impermeability, and subgrade deformation. Different insulation boards were compared when they were applied in the construction. Study shows that XPS is a new feasible and economical insulation material of high performance.