Deformation Behavior for Different Layered Cushion Material After Freeze-Thaw Cycles

Layered cushion material is widely used in concrete-faced rockfill dams and embankment of highway. The deformation of the cushion material is dominant to the safety of the concrete face or pavement. If the total or differential deformation of cushion material is too large, cracks may develop in concrete face or pavement, and even more destruction may happen to the whole structure. In cold area, the excessive deformation of cushion material may happen because of repeated frost heave and thaw collapse during freeze-thaw cycles. For better understanding on this excessive deformation and optimum design for cushion material, series laboratory tests are carried out on four types of samples with different layered structure. A self-developed one-dimensional freeze-thaw device is used to monitor the deformation of specimen during freeze-thaw cycles. Test results show that it’s not always frost heave or thaw collapse during freeze-thaw cycles. All specimen show collapse during frost and heave while thaw in the first freeze-thaw cycle. Comparisons are conducted on the four types of layered samples. Comparison results show that the sample with a “loose top and dense bottom” structure deforms relatively small out of four types of layered samples. It also shows that the deformation of frost heave and thaw collapse tends to a stable value along with the freeze-thaw cycles increasing.