Abstract: Depending on the analysis of the differential settlement issue in an airport built in west China，it was found that pot-cover effect was one of the most important causes of damages in built airport． Based on the mechanism of potcover effect，it was pointed out that even in arid area with low underground water level，pot-cover effect could also increase the water content of the soil beneath the nonporous cladding，which would lead to differential settlement， frost heaving or other disasters in such field． So，much attention should be paid to thaw geological phenomenon．