Effect of Pile Installation on Static and Dynamic Properties of Soft Clays

Static and dynamic soil properties were monitored around a closed-ended steel pipe pile driven in a deep deposit of San Francisco Young Bay Mud. Shear wave velocity measurements were taken prior to pile driving to establish the baseline condition and at selected times after pile driving to document the changes as a function of time. Additional instrumentation and monitoring activities included pore water pressure response and lateral soil deformations as a result of pile driving. A series of conventional laboratory tests were performed on samples collected prior to pile driving and 8 months afterwards. Field measurements after pile driving indicate a significant increase of shear wave velocity as a function of time accompanied by excess pore pressure dissipation. Laboratory tests show a significant increase in the strain to failure with slight increases in undrained strength.