Location

Arlington, Virginia

Session Start Date

8-11-2008

Session End Date

8-16-2008

Abstract

Settlement during hydro-testing of two 30-m diameter oil tanks was generated mostly by a layer of highly plastic clay at about 10 m depth. Based on about 5 months of readings on one of the tanks, the total predicted settlement at the tank perimeter was about 300 mm (with little differential movement) and at the center was closer to 550 mm. The settlement of a 7-m diameter water tank located close to the oil tanks followed quite a different pattern during hydro-testing. Within about 6 days, the tank had settled about 130 mm on one side, but only about 20 mm on the other. The water tank was only about half the height of the oil tank, and the diameter was less than one quarter, resulting in loading at the depth of the plastic clay layer of less than 15% of that of the oil tank. Yet, settlement rates were much faster than those of the oil tank, and differential settlement was not anticipated based on the depth of the clay layer. This paper describes the settlement measurements and computations made for the oil tanks and describes the efforts made to determine the reasons for the unanticipated settlement of the water tank and the actions taken to remedy the situation.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Sixth Conference

Publisher

Missouri University of Science and Technology

Publication Date

8-11-2008

Document Version

Final Version

Rights

© 2008 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Aug 11th, 12:00 AM Aug 16th, 12:00 AM

Tank Settlement Due to Highly Plastic Clays

Arlington, Virginia

Settlement during hydro-testing of two 30-m diameter oil tanks was generated mostly by a layer of highly plastic clay at about 10 m depth. Based on about 5 months of readings on one of the tanks, the total predicted settlement at the tank perimeter was about 300 mm (with little differential movement) and at the center was closer to 550 mm. The settlement of a 7-m diameter water tank located close to the oil tanks followed quite a different pattern during hydro-testing. Within about 6 days, the tank had settled about 130 mm on one side, but only about 20 mm on the other. The water tank was only about half the height of the oil tank, and the diameter was less than one quarter, resulting in loading at the depth of the plastic clay layer of less than 15% of that of the oil tank. Yet, settlement rates were much faster than those of the oil tank, and differential settlement was not anticipated based on the depth of the clay layer. This paper describes the settlement measurements and computations made for the oil tanks and describes the efforts made to determine the reasons for the unanticipated settlement of the water tank and the actions taken to remedy the situation.