Necessity of cooling methods for transportation infrastructure construction in permafrost regions of Qinghai–Tibet Plateau

摘要

A key issue in ensuring the stability of transportation infrastructure in permafrost regions of the Qinghai-Tibet Plateau (QTP) is to prevent the degradation of the underlying permafrost. Therefore, several cooling methods (such as sun sheds, duct-ventilated embankment, thermosyphon, crushed-rock embankment, and dry bridge) have been developed to stabilize the underlying permafrost and mitigate thaw settlement. In this study, considering climate warming and engineering geologic conditions, a necessity model of cooling methods for transportation infrastructure was proposed. The application features of cooling methods along the Qinghai-Tibet Railway (QTR) in permafrost regions were systematically and comprehensively summarized to validate the model accuracy. The results indicated that the model has satisfactory performance and can determine the necessity index (NI) of cooling methods in a certain area. Based on the NI values, convenient application criteria for cooling methods were proposed. Specifically, the transportation infrastructure can be constructed without cooling methods in regions where the NI is less than 1.088. The results indicated that approximately 97% of the regions (NI 1.088) in the study area are located in talik and low-temperature and ice-poor permafrost regions. Therefore, NI = 1.088 was determined to be a reasonable boundary value for deciding whether to apply cooling methods. Finally, the reliability of the criteria was validated by analyzing the settlement data of six typical embankment sections. This model can improve the reasonableness of the decision-making process of cooling method selection during the design and construction of transportation infrastructure, not only in the Qinghai-Tibet engineering corridor but also in a wide region of the QTP.