Experimental Studies of Squat Gravity Caissons and Monopiles for Offshore Applications

Ryan Beemer

Research output: ThesisNon-UWA Thesis

Abstract

This dissertation presents initial results from geotechnical centrifuge experiments on squat gravity caissons and monopiles under cyclic eccentric loading in soft clay under undrained conditions. These experiments were conducted in the 1-g laboratory at Texas A&M University and the 150g-ton centrifuge at Rensselaer Polytechnic Institute. All tested caissons had a length to diameter aspect ratios of two with four tested in the 1-g laboratory and four caissons tested in the centrifuge. Though this aspect ratio is a bit atypical, it could be a reasonable option for offshore renewable hydrokinetic systems or a component in tripod or tetrapod wind tower foundation systems. 1-g experimental results focus of the effect of caisson interior venting on capacity. Centrifuge experimental results focus on behavior arising from an unrestricted vertical coordinate, allowing self-weight to contribute to combined loading, the impact of depth of rotation on caisson resistance, and the global stiffness and damping ratio of the caissons. With the advent of high accuracy sensors and increased interest in geotechnical centrifuge testing simulating loading within serviceability limits a stronger understanding the strength and orientation of centrifuge gravity relative to the scale model is necessary. This dissertation presents a methodology for determining the 2-Dimensional centrifuge gravity within a model independent of centrifuge type or geometry. This can be used to recompose the gravity field from the direct measurement of single gravity vector, given angular velocity. Finally, the methodology is compared to the mechanics of drum and beam centrifuges to provide physical meaning to coordinate rotation variables. Microelectromechanical systems (MEMS) accelerometers are becoming more prevalent in geotechnical engineering and geotechnical centrifuge modeling. In geotechnical centrifuge experiments these sensors have shown much promise, but still exhibit some limitations. This dissertation proposes a new methodology for the use of single-axis low g, high accuracy, MEMS accelerometers to measure orientation of on object in a geotechnical centrifuge. The inclusion of the measured component of cross-axis in orientation calculations significantly improves measurements of absolute orientation, a 3.8º improvement in this study, and reduces errors in orientation measurement by allowing high accuracy low-g accelerometers to be used in the centrifuge.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Texas A and M University
Supervisors/Advisors
  • Aubeny, Charles, Supervisor, External person
Award date5 May 2016
Publication statusUnpublished - 2016

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offshore application
caisson
centrifuge
experimental study
gravity
accelerometer
methodology
sensor
centrifugal model test
tetrapod
experiment
venting
soft clay
geotechnical engineering
cyclic loading
gravity field
mechanics
damping

Cite this

@phdthesis{262c411403064aafb70cda7aeb5087a4,
title = "Experimental Studies of Squat Gravity Caissons and Monopiles for Offshore Applications",
abstract = "This dissertation presents initial results from geotechnical centrifuge experiments on squat gravity caissons and monopiles under cyclic eccentric loading in soft clay under undrained conditions. These experiments were conducted in the 1-g laboratory at Texas A&M University and the 150g-ton centrifuge at Rensselaer Polytechnic Institute. All tested caissons had a length to diameter aspect ratios of two with four tested in the 1-g laboratory and four caissons tested in the centrifuge. Though this aspect ratio is a bit atypical, it could be a reasonable option for offshore renewable hydrokinetic systems or a component in tripod or tetrapod wind tower foundation systems. 1-g experimental results focus of the effect of caisson interior venting on capacity. Centrifuge experimental results focus on behavior arising from an unrestricted vertical coordinate, allowing self-weight to contribute to combined loading, the impact of depth of rotation on caisson resistance, and the global stiffness and damping ratio of the caissons. With the advent of high accuracy sensors and increased interest in geotechnical centrifuge testing simulating loading within serviceability limits a stronger understanding the strength and orientation of centrifuge gravity relative to the scale model is necessary. This dissertation presents a methodology for determining the 2-Dimensional centrifuge gravity within a model independent of centrifuge type or geometry. This can be used to recompose the gravity field from the direct measurement of single gravity vector, given angular velocity. Finally, the methodology is compared to the mechanics of drum and beam centrifuges to provide physical meaning to coordinate rotation variables. Microelectromechanical systems (MEMS) accelerometers are becoming more prevalent in geotechnical engineering and geotechnical centrifuge modeling. In geotechnical centrifuge experiments these sensors have shown much promise, but still exhibit some limitations. This dissertation proposes a new methodology for the use of single-axis low g, high accuracy, MEMS accelerometers to measure orientation of on object in a geotechnical centrifuge. The inclusion of the measured component of cross-axis in orientation calculations significantly improves measurements of absolute orientation, a 3.8º improvement in this study, and reduces errors in orientation measurement by allowing high accuracy low-g accelerometers to be used in the centrifuge.",
keywords = "Monopile, Caissson, MEMS Acclerometer, Geotechnical Centrifuge, Cantrifuge",
author = "Ryan Beemer",
year = "2016",
language = "English",
school = "Texas A and M University",

}

Beemer, R 2016, 'Experimental Studies of Squat Gravity Caissons and Monopiles for Offshore Applications', Doctor of Philosophy, Texas A and M University.

Experimental Studies of Squat Gravity Caissons and Monopiles for Offshore Applications. / Beemer, Ryan.

2016.

Research output: ThesisNon-UWA Thesis

TY - THES

T1 - Experimental Studies of Squat Gravity Caissons and Monopiles for Offshore Applications

AU - Beemer, Ryan

PY - 2016

Y1 - 2016

N2 - This dissertation presents initial results from geotechnical centrifuge experiments on squat gravity caissons and monopiles under cyclic eccentric loading in soft clay under undrained conditions. These experiments were conducted in the 1-g laboratory at Texas A&M University and the 150g-ton centrifuge at Rensselaer Polytechnic Institute. All tested caissons had a length to diameter aspect ratios of two with four tested in the 1-g laboratory and four caissons tested in the centrifuge. Though this aspect ratio is a bit atypical, it could be a reasonable option for offshore renewable hydrokinetic systems or a component in tripod or tetrapod wind tower foundation systems. 1-g experimental results focus of the effect of caisson interior venting on capacity. Centrifuge experimental results focus on behavior arising from an unrestricted vertical coordinate, allowing self-weight to contribute to combined loading, the impact of depth of rotation on caisson resistance, and the global stiffness and damping ratio of the caissons. With the advent of high accuracy sensors and increased interest in geotechnical centrifuge testing simulating loading within serviceability limits a stronger understanding the strength and orientation of centrifuge gravity relative to the scale model is necessary. This dissertation presents a methodology for determining the 2-Dimensional centrifuge gravity within a model independent of centrifuge type or geometry. This can be used to recompose the gravity field from the direct measurement of single gravity vector, given angular velocity. Finally, the methodology is compared to the mechanics of drum and beam centrifuges to provide physical meaning to coordinate rotation variables. Microelectromechanical systems (MEMS) accelerometers are becoming more prevalent in geotechnical engineering and geotechnical centrifuge modeling. In geotechnical centrifuge experiments these sensors have shown much promise, but still exhibit some limitations. This dissertation proposes a new methodology for the use of single-axis low g, high accuracy, MEMS accelerometers to measure orientation of on object in a geotechnical centrifuge. The inclusion of the measured component of cross-axis in orientation calculations significantly improves measurements of absolute orientation, a 3.8º improvement in this study, and reduces errors in orientation measurement by allowing high accuracy low-g accelerometers to be used in the centrifuge.

AB - This dissertation presents initial results from geotechnical centrifuge experiments on squat gravity caissons and monopiles under cyclic eccentric loading in soft clay under undrained conditions. These experiments were conducted in the 1-g laboratory at Texas A&M University and the 150g-ton centrifuge at Rensselaer Polytechnic Institute. All tested caissons had a length to diameter aspect ratios of two with four tested in the 1-g laboratory and four caissons tested in the centrifuge. Though this aspect ratio is a bit atypical, it could be a reasonable option for offshore renewable hydrokinetic systems or a component in tripod or tetrapod wind tower foundation systems. 1-g experimental results focus of the effect of caisson interior venting on capacity. Centrifuge experimental results focus on behavior arising from an unrestricted vertical coordinate, allowing self-weight to contribute to combined loading, the impact of depth of rotation on caisson resistance, and the global stiffness and damping ratio of the caissons. With the advent of high accuracy sensors and increased interest in geotechnical centrifuge testing simulating loading within serviceability limits a stronger understanding the strength and orientation of centrifuge gravity relative to the scale model is necessary. This dissertation presents a methodology for determining the 2-Dimensional centrifuge gravity within a model independent of centrifuge type or geometry. This can be used to recompose the gravity field from the direct measurement of single gravity vector, given angular velocity. Finally, the methodology is compared to the mechanics of drum and beam centrifuges to provide physical meaning to coordinate rotation variables. Microelectromechanical systems (MEMS) accelerometers are becoming more prevalent in geotechnical engineering and geotechnical centrifuge modeling. In geotechnical centrifuge experiments these sensors have shown much promise, but still exhibit some limitations. This dissertation proposes a new methodology for the use of single-axis low g, high accuracy, MEMS accelerometers to measure orientation of on object in a geotechnical centrifuge. The inclusion of the measured component of cross-axis in orientation calculations significantly improves measurements of absolute orientation, a 3.8º improvement in this study, and reduces errors in orientation measurement by allowing high accuracy low-g accelerometers to be used in the centrifuge.

KW - Monopile

KW - Caissson

KW - MEMS Acclerometer

KW - Geotechnical Centrifuge

KW - Cantrifuge

M3 - Non-UWA Thesis

ER -