Abstract:The thermal regime of larger diameter cast-in-place pile in group in high-temperature permafrost regions has seldom been reported. Field observation shows that the heat from circulating slurry and concrete pile rather disturb the thermal regime of the frozen ground during the percussion drilling process and the cement hydration period. The increasing rate of temperature in different layers of frozen soil varies with the ice content and the initial temperature in frozen soil. At the end of the cement hydration exothermic period,the raising temperature of the frozen soil and the decreasing temperature of the concrete pile tend to be the same value-the thawing temperature of frozen soil. After 180 day increasing,the temperature of frozen soil begins to drop slowly at the rate of 0.02 ℃/(60 d). Although the upper layer soil can be cooled down directly in the following winter,it is warmed up again afterwards while pit is excavated and the low built base slab of abutment is cast in warm weather. In the layer beyond the direct affect of the air temperature,the temperature decreasing (refreezing) process is quite slow,so it is difficult for the thawing high temperature permafrost around the cast-in-place pile in group to refreeze in the short construction period.