Thermal stability investigation of wide embankment with asphalt pavement for Qinghai-Tibet expressway based on finite element method

This study aims to analyze the thermal regime and stability of wide embankment in permafrost regions to facilitate the future construction of Qinghai-Tibet Expressway. Based on finite element method, thermo-hydro-mechanical coupling model was built to investigate the thermal stability and thawing settlement of embankments. The validity was verified by field observed data from Qinghai-Tibet Highway. Based on numerical analysis, the temperature field, thawing depth and thawing settlement of embankments with different width were investigated. The influences on the thermal stability of embankments by different protective measures such as raising height of embankment, setting crushed stone layer in embankment, setting Expanded Polystyrene (EPS) layer in embankment and setting the combination of crushed stone layer and EPS layer in embankment were evaluated. It was found that embankment construction has serious disturbance on the thermal stability of ground permafrost. Meanwhile, larger embankment width leads to worse thermal stability of ground permafrost and more serious thawing settlement of embankment. Increasing the embankment height can improve the thermal regime of embankment, however, the thawing settlement and differential thawing settlement of embankment get worse with bigger embankment height. Setting crush rock layer or EPS layer can improve the thermal stability of embankment, however, the improvement is limited for wide embankment with width exceeding 26 m. The combination of crush rock layer and EPS layer has the best protective effects on the thermal stability of wide embankment, however, the differential thawing settlement under pavement still needs to be paid attentions to.