Options
Gavin, Kenneth
Preferred name
Gavin, Kenneth
Official Name
Gavin, Kenneth
Research Output
Now showing 1 - 4 of 4
- PublicationDynamic soil-structure interaction modeling using stiffness derived from in-situ Cone Penetration Tests(2014-05-14)
; ; This paper presents the results of an experimental and numerical investigation into the natural frequency of a pile driven into dense sand. The experimental arrangement involves fitting accelerometers along the pile shaft and using a modal hammer to induce lateral vibration. The natural frequency is obtained by performing Fourier analysis on the acceleration signals. A numerical model is developed that models the pile as a beam supported by lateral springs. The natural frequency is obtained by performing an eigenvalue analysis in the numerical model. The spring stiffness is derived by first obtaining the G0 value for the sand at the installation location. This is achieved using the rigidity index, a correlation between the cone tip resistance qc value and the small-strain shear modulus G0. The G0 value is converted to lateral spring stiffness values using an equation derived analytically from the beam on an elastic foundation case. Good agreement is observed between the experimentally measured natural frequency and that which is calculated from the numerical model. This research paves the way for more accurate assessments of dynamic soil-structure interaction, and can be particularly useful in the design of structures that are dynamically sensitive such as wind turbines.289 - PublicationSoil properties at the UCD geotechnical research site at Blessington(2012-09-06)
; ; ; ; ; ; Over the past ten years, the Geotechnical Research Group (GRG) at University College Dublin have developed a research site at Blessington, County Wicklow, for the purpose of testing foundation systems. This paper presents the results of field and laboratory tests conducted to obtain the geotechnical parameters of Blessington sand. The in-situ tests included cone penetration and dilatometer tests. Sonic coring was performed in three boreholes at the site and complete recovery was obtained in boreholes up to 14 m deep. Additional disturbed samples were taken from trial pits which were up to 6 m deep. The classification tests performed on samples compared favourably with those inferred from correlations with in-situ test data. The strength, stiffness and mineralogy were also determined by a suite of laboratory tests including SEM imagery, triaxial tests and ring shear testing. The accuracy of conventional correlations in predicting the laboratory measured parameters is discussed.610 - PublicationThe Development and Testing of an Instrumented Open-Ended Model PileThis paper describes the development of a model instrumented open-ended (pipe) pile. The importance of model geometry and separating the shaft, annular and plug load, and horizontal effective stresses is discussed. A detailed description of the construction of the twin-walled open-ended pile is presented. Particular attention was given to protecting the fragile instrumentation from the rigours of installation and the effects of water ingress. Calibration procedures, which were used to verify the instrument reliability, are also discussed. The final section describes field tests conducted in both loose sand and medium-dense sand deposits, which are used to validate the instrument performance.
649Scopus© Citations 20 - PublicationPiles for offshore wind turbines: A state of the art reviewThe paper considers the current state of the art for estimating the pull-out capacity of driven open-ended piles used to support wind turbine foundations founded on sand. The latest edition of the American Petroleum Institute guidelines for pile design includes a conventional earth pressure approach and four alternative cone penetration test (CPT) methods for estimating pile shaft resistance in sand. A database of open-ended pile tests was used to assess the predictive reliability of the design approaches. While the earth pressure approach was unreliable, exhibiting bias with pile slenderness and sand relative density, the CPT methods were shown to provide improved and relatively consistent estimates of pile capacity. However, the tension loads experienced by wind turbine foundations are significantly higher than those applied to piles in the database. When the CPT methods were used to estimate the pile length required to support a 5 MW turbine installed in typical offshore soil conditions, the CPT methods provided a wide range of predicted pile lengths. The reasons for this divergence are discussed and an alternative framework for considering driven pile shaft resistance is put forward.
1463Scopus© Citations 58