Liquefaction Induced by Auger-Cast Piles: How Common?

Clear water was observed percolating from the tops of fresh auger-cast piles and from the surrounding ground. This transient event, typically lasting less than an hour, occurred in approximately 40% of nearly 700 piles. The percolating water was apparently due to liquefaction of saturated loose to very loose sand, induced by the auger during installation of the piles. The liquefaction water was observed during this project because of a locally high water table; however, temporary flow of excess pore water through fresh grout must be a regular occurrence in loose sands, but is usually unnoticed because the groundwater table is normally well below the ground surface.