Field Tests to Investigate the Installation Effects of Drilled Displacement Piles with Screw-Shaped Shaft in Clay

Abstract

This technical note presents a detailed field study to investigate the installation effects of drilled displacement (DD) piles with a screw-shaped shaft in Shanghai soft clay. Horizontal soil displacements and pore water pressures were measured in the vicinity of two DD piles with a screw-shaped shaft during their installation and subsequent soil consolidation periods. The results show that the horizontal soil displacements induced by the installation of a DD pile with a screw-shaped shaft are mainly concentrated within a circular region with a radius smaller than six times the pile external diameter and that the maximum horizontal soil displacements decrease by 10–20% one day after concreting and then tend to be stable. The excess pore water pressures reach their maximum when the drilling rod reaches the design depth or the concreting is completed and then start to decrease with time following approximately an exponential decay function.