Long-Term Use of Diatomite Slope Embankments in Warm Permafrost Regions

摘要

Diatomite is a highly porous media with significant water absorption and retention capacity. In order to investigate the long-term cooling effect of diatomite on a roadbed in a warm permafrost region, a diatomite embankment was constructed in 2003, on National Highway 214, Qinghai-Tibet Plateau. Field data revealed that surface temperature differences between embankments with and without diatomite varied from 0.3 to 1.8 degrees C. According to permafrost tables and mean annual ground temperatures, the thermal semiconductivity of a 0.4-m thick diatomite slope only impeded permafrost degradation, but did not offset the temperature rise associated with installing an asphalt pavement and embankment in warm permafrost regions. Further analysis indicated that the initial cooling effect of the diatomite slope was influenced by the construction season and watering treatment. Additionally, maintenance and climatic conditions were important for the long-term thermal performance of the diatomite embankment. The results show that diatomite slopes should be considered in humid climates with high levels of autumn rainfall, and should ideally be constructed at the end of winter.