Alan J. Lutenegger
The purpose of this research was to determine how soil disturbance caused by the installation of piles (of differing types and geometries) in clay affect the short and long-term capacity of piles. Several types of piles were installed in lightly overconsolidated clay at three different test sites in Amherst, Massachusetts. Before and after pile installation, an in-situ testing program consisting of field vane shear tests was carried out around piles installed at one of the three testing sites. Undrained shear strength and water content profiles allowed for an approximate determination of changes in the behavior of the clay surrounding some of the piles installed at different aging periods. The excess pore pressures within the soil surrounding the piles was monitored during and after pile installation by means of collected representative samples located at various depths immediately adjacent to the pile. The changes in pore pressure during pile installation were indicators of the soil deformations caused by the pile installation. After allowing a recovery period following installation (at all sites), piles with differing geometries were loaded to failure under axial tensile loads. Load-settlement curves were generated for different piles at different aging times after installation. The Undrained Shear Strength of the clay adjacent to the pile was also monitored at different aging times after installation by performing field vane tests. Disturbed samples were collected after each test to monitor the water content. The determined water content at different aging times was used as an indicator of the distribution of excess pore pressures and distribution of soil deformations caused by pile displacement. The Undrained Shear Strengths and water content were used as principal parameters (controlling factors) for the correlation to the short and long-term capacity of the pile.