Influence of freeze tube deviation on the development of frozen wall during long cross-passage construction

Abstract

This paper investigates the influence of the deviation in freeze pipe installation on the development of the frozen wall in long cross passages by numerical simulation with ANSYS software. The study case is from the artificial ground freezing project along the Fuzhou Metro Line 2 between Ziyang Station and Wuliting Station. Two freeze-pipe configurations, i.e., one with perfectly aligned pipes without any deviation from design and another with randomly distributed deviation, are included for comparison. The effect of the random deviation in the freeze pipes on frozen wall interconnection time, the thickness of the frozen wall and the development of the temperature field is explored. For the characteristic section of the numerical model at a depth of 25 m, it is found that the frozen wall interconnection time under the random deviation case and no deviation case is 24 days and 18 days, respectively. The difference in the thickness of the thinnest frozen wall segment between the random deviation and no deviation cases is the largest in the early freezing stage (up to 0.75 m), which decreases with time to 0.31 m in the late freezing stage. The effects of random deviation are more significant in the early freezing stage and diminish as the freezing time increases.