Pipe pile installation effects in soft clay

Abstract

The shortage of field measurements to examine existing predictive methods for pipe piles in clay prompted an experimental programme in Shanghai, China, in which displacements and stresses were measured in the vicinity of two pipe piles during their installation in a soft lightly overconsolidated clay. The test programme was also conducted to assist assessment of the installation effects associated with a recently patented cast-in-place concrete pipe pile, referred to as the PCC pile. The field measurements are compared with existing predictive methods such as the shallow strain path and cavity expansion methods (SSPM and CEM). The SSPM is shown to be the most suitable for the prediction of ground displacements, although the more straightforward CEM can provide realistic predictions of radial movements when calculations are performed using a solid pile with an area equivalent to that of the annulus of the pipe pile. Installation-induced excess pore pressures remote from pipe piles are also shown to be well predicted using the same cavity expansion method combined with this equivalent radius, while changes in lateral total stress display a faster degradation than that of the theoretical predictions. The paper provides verification of an expedient means of assessing installation disturbance due to undrained pipe pile installation.