The liquefaction of saturated fine sand is a crucial difficulty hindering the development of long auger cement fly-ash gravel (CFG) pile construction technology. However

the relationships between liquefaction and two construction-related parameters of CFG piles

namely the pile spacing and the pipe rotation speed

during the piling process have not been well investigated. Thus

in this paper

the influences of these two parameters on the liquefaction of saturated fine sand are analyzed

and the relationships between the two parameters and liquefaction are established. Besides the theoretical studies

an experiment platform is also established to reproduce the construction process of a long auger CFG pile in the saturated fine sand. The results of laboratory tests show that the increase of pipe rotation speed and the decrease of pile spacing promote the liquefaction of saturated fine sand

shorten the pile length

and increase the pile diameter. In order to relieve the liquefaction of saturated sand

the pipe rotation speed should be reduced and the pile spacing should be increased.