Session Start Date

6-1-1988

Abstract

A case history of the foundation behaviour of an offshore gravity base structure (GBS) is presented. The platform rests on an overconsolidated fissured clay, bounded, top and bottom, by pervious sand layers. Sixteen piezometers have been placed within this 30 m layer. Based on one-dimensional consolidation theory, independent analyses using both settlement and pore pressure measurements indicated a high degree of consolidation had occurred much sooner than was estimated in the initial design phase. These analyses indicated that laboratory oedometer tests underpredicted the coefficient of consolidation by one to two orders of magnitude. Updated settlements and stability analyses yielded 50% of the initially anticipated settlement and a 20% increase in the available safety factor. In addition, the certainty that the theory relating pore pressure to settlements was appropriate, led to confidence in the piezometer performance, and in turn the procedure used to install them.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Second Conference

Publisher

University of Missouri--Rolla

Publication Date

6-1-1988

Document Version

Final Version

Rights

© 1988 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Jun 1st, 12:00 AM

GBS Platform Evaluation Using Field Instrumentation

A case history of the foundation behaviour of an offshore gravity base structure (GBS) is presented. The platform rests on an overconsolidated fissured clay, bounded, top and bottom, by pervious sand layers. Sixteen piezometers have been placed within this 30 m layer. Based on one-dimensional consolidation theory, independent analyses using both settlement and pore pressure measurements indicated a high degree of consolidation had occurred much sooner than was estimated in the initial design phase. These analyses indicated that laboratory oedometer tests underpredicted the coefficient of consolidation by one to two orders of magnitude. Updated settlements and stability analyses yielded 50% of the initially anticipated settlement and a 20% increase in the available safety factor. In addition, the certainty that the theory relating pore pressure to settlements was appropriate, led to confidence in the piezometer performance, and in turn the procedure used to install them.