UC Davis

Sonic drilling is an efficient and versatile drilling technique used to continuously core soils and soft rock, and it is increasingly used for geotechnical site characterization. During sonic drilling, the sonic head and attached drill string are vibrated to advance the drill string into the subsurface. These vibrations are transmitted to and propagated through the surrounding soil, causing some amount of disturbance to the soil. However, the magnitude of disturbance as a function of the zone of influence (radial and vertical distance) and soil type has not yet been quantified. This thesis presents the results of two field studies that quantify the sonic induced soil disturbance with an array of installed instrumentation. In addition, as an indicator of the possible disturbance to in-situ tests or soil sampling below the bit, changes in baseline measured CPT parameters are evaluated when a CPT sounding is performed into soils immediately below the sonic casing.