Scale Model Investigation of Pipe Pile Plugging

About eight 1:50 scale-model open-ended pile driving tests investigated the development of soil plugging. Scale test piles represent full scale 0.322 m (1 ft) and 0.635 m (2 ft) diameter piles, 20 m (66 ft) and 30 m (98 ft) long, driven into a medium sand of two densities. Pile driving hammer and drop height were scaled in addition to pile diameter, length, and soil grain size. The pile driving record and visual observations of localized down drag corresponded with anticipated full-scale behavior. Evaluation of plug length ratios and incremental filling ratios show the expected independence of plug length development on overall pile length. Soil density and pile diameter influenced plug length development. A dimensionless normalizing ratio based on driven length, nominal grain size, and inside and outside pipe diameters effectively normalizes the data. Soil density alone influences the relationship between the dimensionless normalizing ratio and plug length ratio. Scale-model testing provides a viable, if simplified, method for exploring soil plugging in open-ended pipe piles.