Proceedings of the 45th Annual Conference on Deep Foundations, 2020 - ONLINE , (DFI)
Geophysical Investigations Enhance Geologic Characterization in Support of Pile Foundation Program
Michael Oakland, PE, PhD, Mario Carnevale, MSc., P.G., Myles Danforth, BSc.
The cost and overall effectiveness of foundation design depends on a robust characterization of the subsurface geologic setting. It is common practice to formulate deep foundation design from subsurface geologic characterization based on boring programs. The confidence level of geologic characterization is directly related to that of geologic interpretations, which are based on the spatial sampling pattern of boreholes relative to the complexity of the geologic setting. This paper presents a case history illustrating issues that arise during pile construction from over-simplified geologic characterization, the challenging steps taken to improve the subsurface geologic model, and the effect of additional characterization efforts on the pile foundation program. The seismic characterization methods used include multi-channel analysis of surface waves (MASW) and seismic refraction. Located at the water's edge, the site's natural post-glacial depositional history, as well as artificial fill emplacement, provide context for initial and subsequent geologic characterization. This paper will illustrate that the pile selection parameters based on the initial characterization could have been “fine- tuned” with more detailed subsurface geophysical investigations, thereby resulting in savings of material and labor cost. Details of the geophysical seismic surveys and analyses used in improving the geologic models of the project site will be discussed.
|article #3677; publication #1073 (AM-2020)|