Evaluation of the application effect of the inclined TPCTs on an embankment with the shady-sunny slope effect in permafrost regions

As an efficient engineering technology, the inclined two-phase closed thermosyphons (ITPCTs) are extensively adopted in the Qinghai-Tibet Highway (QTH) to prevent permafrost degradation. However, cracks still appear on the bituminous pavement of the ITPCTs embankment, which threatens the traffic safety. It is necessary to evaluate the application effect of ITPCTs and analyze the process of crack formation. In this study, a coupled hydro-thermo-mechanical (HTM) model for the ITPCTs embankment is proposed, and the cooling effect and restraining function of the ITPCTs are numerically evaluated by comparison the ground temperature, water content distribution and deformation process of the ITPCTs embankment and an unprotected embankment (UE). Then, the cause for longitudinal crack on the ITPCTs embankment is revealed, and the initiation time and occurrence location of longitudinal crack are determined. Finally, the spatial-temporal development of longitudinal crack is analyzed. Additionally, based on the cause for longitudinal cracks, some comprehensive measures to prevent and treat cracks are suggested. This study can serve as a reference for the maintaining the ITPCTs embankment in the QTH and designing the Qinghai-Tibet Expressway in the near future.