Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-10-2013

Abstract

When wind turbines are to be installed offshore, expensive geotechnical in-situ tests are carried out at the location of each turbine and only a quantile value (typically the 5% quantile) of the measured strength parameters is used as design parameter, e.g., the 5% quantile value of the undrained shear strength of the soil. Typically, measurement, statistical and model uncertainties are not taken into account in code-based, deterministic design. Hence, current methodology based design may be expensive, but the reliability of the foundation is unknown. Instead, a reliability-based design process based on stochastic analysis of the soil parameters is proposed to obtain an efficient design with known reliability and smaller costs for tests and construction. In this study a monopile foundation in undrained, over-consolidated clay is considered as an example. A three-dimensional (3D) finite-element model is established and a stochastic model for the undrained shear strength of the soil is proposed using random field theory. The Mohr–Coulomb constitutive model is used to model the soil behavior. Reliability indices of the monopile are obtained through an advanced reliability method and a probabilistic procedure is proposed regarding the 3D design of monopile foundations.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Seventh Conference

Publisher

Missouri University of Science and Technology

Publication Date

4-29-2013

Document Version

Final Version

Rights

© 2013 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 29th, 12:00 AM May 10th, 12:00 AM

Probabilistic Three-Dimensional Model of an Offshore Monopile Foundation: Reliability Based Approach

Chicago, Illinois

When wind turbines are to be installed offshore, expensive geotechnical in-situ tests are carried out at the location of each turbine and only a quantile value (typically the 5% quantile) of the measured strength parameters is used as design parameter, e.g., the 5% quantile value of the undrained shear strength of the soil. Typically, measurement, statistical and model uncertainties are not taken into account in code-based, deterministic design. Hence, current methodology based design may be expensive, but the reliability of the foundation is unknown. Instead, a reliability-based design process based on stochastic analysis of the soil parameters is proposed to obtain an efficient design with known reliability and smaller costs for tests and construction. In this study a monopile foundation in undrained, over-consolidated clay is considered as an example. A three-dimensional (3D) finite-element model is established and a stochastic model for the undrained shear strength of the soil is proposed using random field theory. The Mohr–Coulomb constitutive model is used to model the soil behavior. Reliability indices of the monopile are obtained through an advanced reliability method and a probabilistic procedure is proposed regarding the 3D design of monopile foundations.