Abstract：Based on the field geological investigation at permafrost regions，geological description and field test of waves velocities at 14 typical boreholes distributing in permafrost areas along the Qinghai—Tibet Railway，elementary characteristics of wave velocities of soils at the permafrost regions are presented. And then，combining the results of dynamic triaxial test，using three time histories of ground motion acceleration with the exceedance probabilities 62.5%，10.0% and 2.0% in 50 years related to the research area，the characteristics of ground motion are analyzed for the 10 permafrost profiles by an equivalent linearization method to estimate the seismic response of frozen soil ground. Moreover，the influence of earth temperature on seismic acceleration response spectrum for permafrost sites is studied. Consequently，the following conclusions can be drawn. (1) Under the similar conditions，the wave velocities of frozen soils along the Qinghai—Tibet Railway are greater than those of other non-frozen soils areas；and the velocity ratio between the shear wave and compression wave does the same. (2) Earthquake intensity is a critical factor to influence the acceleration amplitude of ground motion at permafrost regions，e.g. with the decrease of earthquake intensity，the acceleration amplitude of the ground motion reduces gradually. (3) The proportion of the moderate and the short periods of seismic acceleration response spectrum in permafrost regions is primary. (4) The amplitude of acceleration response spectrum of ground motion decreases distinctly while earth temperature of frozen soils reduces. The research should contribute to earthquake disaster prevention of engineering structures in permafrost areas on Qinghai—Tibet Plateau.
