Freeze–thaw characteristics and long-term effects of applying a capillary drainage plate in a subgrade in a plateau highway: Insights from laboratory and numerical investigations

Abstract

This study considered cyclic freeze–thaw tests via laboratory and numerical simulations to verify the applicability of a polyvinyl chloride (PVC) capillary drainage plate (CDP) in subgrades in regions with seasonally frozen soil. Laying the PVC CDP in the soil of a subgrade contributed significantly to draining and binding the soil, resulting in less freeze–thaw damage of the subgrade. The results showed that the presence of the PVC CDP reduced the water content of the subgrade by 7.09% after four freeze–thaw cycles. The maximum frost heave displacement and thaw settlement of the subgrade decreased by approximately 19.10% and 66.82%, respectively. After four freeze–thaw cycles, the maximum freezing depth was shallower for the subgrade with the PVC CDP than for the subgrade without it. Long-term predictions of the performance of the original subgrade with the PVC CDP were made by numerical simulation, and the long-term freezing displacements and freezing depths of the subgrade with and without the PVC CDP were compared and analysed. The results of the study proved the effectiveness of laying a PVC CDP to prevent damage from subgrade freezing in areas with seasonal permafrost. Additionally, the results of this study can provide a reference for the assessment of the long-term safety of road projects in seasonal permafrost zones.