Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

Abstract

A breakwater embankment was constructed as part of a settling basin for the intake of a thermal power plant in the north of Egypt. The 440-m long breakwater surrounds the intake basin which has an area of about 18000 m2. Sea water is supplied to the intake basin through 50 concrete pipes embedded in the breakwater. Subsurface soil conditions in the area indicated that the embankment would be founded on soft silty clay underlain by a layer of silty sand. Results from the settlement analysis showed that the embedded pipes could not tolerate the predicted differential settlement in the embankment. Accordingly, it was determined that the embankment could not be founded on natural soil and that this soil would require improvement using stone columns. Offshore stone columns were constructed using the blanket method utilizing two vibro flotation probes. The layout was designed such that the stone columns were arranged in a triangular pattern below the embedded pipes, and in a rectangular pattern elsewhere. This paper presents the design method using numerical modeling to show the amount of expected settlement with and without stone columns. The method of construction is discussed showing how the stone columns were constructed using the blanket method. The full-scale load test that was constructed offshore to validate the design is described. The results from the load test and post-construction settlement readings indicated that the stone columns proved to be an efficient and economical solution in reducing the differential settlement to tolerable limits for the embedded pipes.

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 4th, 12:00 AM

Offshore Stone Columns Under Embankment With Embedded Pipes

Chicago, Illinois

A breakwater embankment was constructed as part of a settling basin for the intake of a thermal power plant in the north of Egypt. The 440-m long breakwater surrounds the intake basin which has an area of about 18000 m2. Sea water is supplied to the intake basin through 50 concrete pipes embedded in the breakwater. Subsurface soil conditions in the area indicated that the embankment would be founded on soft silty clay underlain by a layer of silty sand. Results from the settlement analysis showed that the embedded pipes could not tolerate the predicted differential settlement in the embankment. Accordingly, it was determined that the embankment could not be founded on natural soil and that this soil would require improvement using stone columns. Offshore stone columns were constructed using the blanket method utilizing two vibro flotation probes. The layout was designed such that the stone columns were arranged in a triangular pattern below the embedded pipes, and in a rectangular pattern elsewhere. This paper presents the design method using numerical modeling to show the amount of expected settlement with and without stone columns. The method of construction is discussed showing how the stone columns were constructed using the blanket method. The full-scale load test that was constructed offshore to validate the design is described. The results from the load test and post-construction settlement readings indicated that the stone columns proved to be an efficient and economical solution in reducing the differential settlement to tolerable limits for the embedded pipes.