Freeze-thaw erosion mechanism and preventive actions of highway subgrade soil in an alpine meadow on the Qinghai-Tibet Plateau

Abstract

Freeze-thaw erosion is widely distributed in China, where the difference of natural conditions brings a series of characteristics for different regions. The alpine meadow area of the Qinghai-Tibet Plateau (QTP) has a special climate, geography, and hydrogeology environment, with multiple road frost heaves and frost boiling failures, which seriously threaten the highway constructions in the QTP. This study summarizes the freeze–thaw geology of the southeastern QTP. For the highway constructions in the frozen soil areas, multiple problems such as frost heave, thawing settlement, freeze–thaw weathering, and pavement cracks and highway operation and management issues may rise as a result of the activity of the freeze–thaw geology, which damages the subgrade structure. To prevent the occurrence of possible hazards and reduce hazards and risks, this study discusses a series of countermeasures and suggestions. A case history is referred to, specifically the Budongquan highway in the QTP, where the study section is conducted, to evaluate the effectiveness of the adopted treatment measures. The results show that these treatment measures effectively prevent the surface water from infiltrating into the subgrade in the rainy season, block the migration of groundwater to the upper subgrade during the freezing season, and discharge the water accumulated in the subgrade as soon as possible after thawing. Thus, this study further understanding of the long-term durability and stability of subgrade, and provide useful information for the structure design of the highway subgrade in cold regions.