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Non-destructive evaluation of foundations
Project Number: A427, A437, A451, A463
Principal Investigator: Richard Finno
1. Project Abstract
2. Final Research Report
3. Publications
Project Abstract:
The purpose of this work is to develop methods to non-destructively evaluate
the condition of existing deep foundations and bridge piers, including the
capability to determine the nature of unknown foundations of bridges. When
evaluating existing foundations, the presence of a pile cap or other structure
often times makes the heads of the concrete piles and shafts inaccessible and
introduces uncertainties in the interpretation of the NDE results. With previous
support, the capabilities of sonic logging, sonic echo, impulse response, and
parallel seismic techniques have been evaluated for determining damage to
accessible and inaccessible drilled shaft foundations. A drilled shaft test
section for non-destructive evaluation (NDE) has been established at the
National Geotechnical Experimentation Sites (NGES) at Northwestern
University.
Experimentation at this test section and subsequent analysis and numerical
simulation have defined the limits of the ability of the impulse response
technique to evaluate damage to drilled shafts in both accessible and
inaccessible head conditions. A multiple geophone method has been
developed which minimized the effects of the surface wave reflections from
intervening pile caps at the NDE test section. The impulse response technique
with and without multiple geophone arrays has been used in the field at a
number of bridge sites. A theory based on guided waves, describing the
relation between frequency and group velocity of frequency-controlled
excitations, has been developed to allow higher frequencies to be used to
evaluate shafts, and, consequently, identify smaller defects than possible with
conventional techniques.
Final Research Report:
NDE of Foundations
Years 1-4 Final Report
A427, A437, A451, A463
NDE of Foundations: Parts I & II (PDF, 14.3 mb)
Publications:
Year |
Title |
Author(s) |
File |
| 1997 | "Non-destructive Evaluation of a Deep Foundation Test Section at the Northwestern University National Geotechnical Experimentation Site" | Richard J. Finno, Sarah L. Gassman, Peter W. Osborn |
