Thermo-seismic performances of a unilateral two-phase closed thermosyphon (TPCT) embankment in earthquake-prone permafrost regions

Abstract

As a device for efficient heat transfer working without external power supply or control instrumentation, a two-phase closed thermosyphon (TPCT) is an engineering instrument for protecting permafrost under embankments from thawing. The process and mechanism of heat transfer in TPCT embankments were well investigated using experimental and theoretical methods. However, the mechanical performance of TPCT embankments is the most key factor controlling safe operation, but it is sometimes ignored. In particular, there are many TPCT embankments located in the earthquake-prone Qinghai-Tibet Plateau (QTP), and their seismic performances dominate their safe operation. To study the seismic characteristic of the TPCT embankment, we established a thermodynamic model for TPCT embankments and selected a unilateral TPCT embankment to simulate the seismic responses over four representative seasons after 10 years in service. The numerical results show the TPCT embankment has lower temperature distributions compared with that of the embankment without TPCTs, and its temperatures exhibit seasonal differences, resulting in differential seismic responses. In general, throughout the year, the seismic responses of the TPCT embankment are more intensive on October 15 and less intensive on January 15. Moreover, distinct sliding planes appear in the TPCT embankment. Therefore, additional reinforcement measurements should be designed to improve the seismic behavior of the TPCT embankment according to the thermal regimes and seismic response characteristics. Meanwhile, this study is a theoretical reference for the construction, maintenance and further study of other TPCT embankments in permafrost regions.