Location

New York, New York

Session Start Date

4-13-2004

Session End Date

4-17-2004

Abstract

In this study, two case histories of deep foundations are discussed, including driven piles and drilled shafts. The first case history is an assessment of driven pile capacity in clay. As part of selecting the deep foundation system, steel pipe, concrete, and timber piles were driven at the site. Static compression and uplift load tests were performed on the concrete and timber piles, while only static compression tests were performed on the steel pipe piles. Measured pile capacities from the static load tests were compared to predicted pile capacities, which were obtained from empirical design methods employing laboratory and in-situ test results. The data demonstrate that the traditional alpha method results in somewhat conservative predictions for the test piles, regardless of whether the values of undrained shear strength (su) are obtained directly from the unconfined compression (UC) test or are inferred from a correlation with the CPTU as equivalent direct simple shear (DSS) values of su. The second case study involves an evaluation of the axial and lateral capacities of drilled shafts in rock to support a concrete gated dam. The test drilled shafts were step-tapered from 5.5-ft diameter through the soil zone to 5-ft diameter in the rock socket. Axial and lateral load tests were performed on drilled shafts embedded in soft to medium hard clayey shale and claystone overlain by granular alluvium. The data demonstrate that longstanding methods of determining ultimate side resistance are conservative relative to the measured values, as are customary presumptive values, but that predictions using one evolving method can be unconservative in the absence of field verification. In addition, the shafts performed satisfactorily under the applied design load, exhibiting minimal lateral deflection within the rock socket.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Fifth Conference

Publisher

University of Missouri--Rolla

Publication Date

4-13-2004

Document Version

Final Version

Rights

© 2004 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 13th, 12:00 AM Apr 17th, 12:00 AM

Driven Pile Capacity in Clay and Drilled Shaft Capacity in Rock from Field Load Tests

New York, New York

In this study, two case histories of deep foundations are discussed, including driven piles and drilled shafts. The first case history is an assessment of driven pile capacity in clay. As part of selecting the deep foundation system, steel pipe, concrete, and timber piles were driven at the site. Static compression and uplift load tests were performed on the concrete and timber piles, while only static compression tests were performed on the steel pipe piles. Measured pile capacities from the static load tests were compared to predicted pile capacities, which were obtained from empirical design methods employing laboratory and in-situ test results. The data demonstrate that the traditional alpha method results in somewhat conservative predictions for the test piles, regardless of whether the values of undrained shear strength (su) are obtained directly from the unconfined compression (UC) test or are inferred from a correlation with the CPTU as equivalent direct simple shear (DSS) values of su. The second case study involves an evaluation of the axial and lateral capacities of drilled shafts in rock to support a concrete gated dam. The test drilled shafts were step-tapered from 5.5-ft diameter through the soil zone to 5-ft diameter in the rock socket. Axial and lateral load tests were performed on drilled shafts embedded in soft to medium hard clayey shale and claystone overlain by granular alluvium. The data demonstrate that longstanding methods of determining ultimate side resistance are conservative relative to the measured values, as are customary presumptive values, but that predictions using one evolving method can be unconservative in the absence of field verification. In addition, the shafts performed satisfactorily under the applied design load, exhibiting minimal lateral deflection within the rock socket.