Seismic Analysis Of Embankment Of Qinghai-tibet Railway

摘要

As far as the railway embankment in permafrost regions is concerned, its mechanical properties are closely related to soil temperature. Especially for the embankment in the warm permafrost regions (mean annual ground temperatures range from 0-1.5 ℃), its stability will change greatly with minor temperature variations. The Qinghai-Tibet Railway (QTR) is approximately 1142 km long, of which 275 km are underlain by warm permafrost. Furthermore, the Qinghai-Tibet Plateau (QTP) is in an active seismic zone. Thus, the seismic stability, liquefaction, and deformation of the embankment of QTR are critical issues on safe operation. However, there are few papers concerning about the seismic response of railway embankment in permafrost regions. This paper will propose a thermal-dynamic coupled model, and the model and its specific analytical procedure can be described as follows. Firstly, based on the governing differential equations of transient temperature field with phase change, the temperature distributions of railway embankment are computed and analyzed by numerical method. Then, since the mechanical properties of frozen soil are effected by temperature, the dynamic consolidation equations of Biot, whose parameters are relative to temperature, are deduced in detail by adopting dynamic consolidation theory. Lastly, by using this numerical model, the seismic response of the QTR embankment is simulated, and the characteristics of seismic response, such as excess pore water pressure, stress and displacement, are analyzed in detail. Meanwhile, the seismic stability of this embankment is evaluated. The results show that this numerical model is able to simulate seismic response of embankment in permafrost regions.