Lessons Learned From the Seismic Retrofit of the Posey and Webster Street Tubes in Alameda County, California

Two historically significant traffic facilities - the Posey and the Webster Street Tubes - link the northern California cities of Oakland and Alameda. The tubes traverse beneath the Oakland Estuary, an arm of the San Francisco Bay. Both tubes are located in a seismically active area between two major active faults - the Hayward Fault (M = 7.25) approximately 5 miles to the east and the San Andreas Fault (M = 8.0) about 14 miles to the west. In 1989, the Loma Prieta Earthquake (M = 7.1), about 57 miles to the south, caused heavy damage to the San Francisco - Oakland Bay Bridge. Although the Posey and Webster Street Tubes sustained only minor damage, the California Department of Transportation (Caltrans) included these vital transportation facilities in its comprehensive seismic retrofit program due to their potential flotation risk from liquefiable soils. In 1995, Parsons Brinckerhoff Quade & Douglas was retained by Caltrans to prepare and develop a retrofit strategy and a Plan/Specification/Estimate package for the seismic retrofit of both tubes. The primary seismic retrofit consisted of jet grout columns and pipe pile stone columns constructed respectively at both sides of the Posey Tube and the Webster Street Tube. These ground improvement methods are the first of their kind ever applied to any immersed tubes of such length. Because of “the first of their kind” nature of the ground improvement work, a demonstration program was conducted in 2000 in order to verify design assumptions and methodologies. Construction of the ground improvement work started in 2002 and successfully completed in 2004. This paper will discuss the seismic retrofit employed, the lessons learned during construction of the jet grout columns and installation of the pipe pile stone columns, as well as the lessons learned from this entire project.

• Corporate Authors:

  Multidisciplinary Center for Earthquake Engineering Research

  State University of New York, 107 Red Jacket Quadrangle, P.O. Box 610025
  Buffalo, NY  United States  14261-0025
• Authors:
  • Lee, Thomas S
  • Anderson, Randy
  • Murray, Rod
• Conference:
  • Fifth National Seismic Conference on Bridges & Highways
  • Location: San Francisco CA, United States
  • Date: 2006-9-18 to 2006-9-20
• Publication Date: 2006

Language

• English

Media Info

• Media Type: CD-ROM
• Features: Figures; References;
• Pagination: 11p
• Monograph Title: Fifth National Seismic Conference on Bridges and Highways: Innovation in Earthquake Engineering for Highway Structures

Subject/Index Terms

• TRT Terms: Earthquake resistant design; Estimation theory; Flotation; Methodology; Planning; Retrofitting; Risk assessment; Seismicity; Specifications
• Identifier Terms: California Department of Transportation; George A. Posey Tube; Webster Street Tube
• Uncontrolled Terms: Assumptions; Ground improvement; Jet grout columns; Liquefiable soils; Stone columns
• Geographic Terms: Alameda (California); Oakland (California); Oakland Estuary; San Francisco Bay
• Subject Areas: Bridges and other structures; Design; Geotechnology; Highways; Planning and Forecasting; I25: Design of Tunnels; I42: Soil Mechanics;

Filing Info

• Accession Number: 01080813
• Record Type: Publication
• Report/Paper Numbers: A24
• Files: TRIS
• Created Date: Nov 15 2007 10:33AM