An Alternative to Sheet Pile Bulkheads at the Bayport Terminal Complex

Abstract

As part of the program management for the Bayport Terminal Complex, an extensive process of value engineering (VE) was carried out both to ensure that the initial Phase 1A fit properly within the overall master site plan, and to optimize the life cycle performance of the selected structural elements. This paper focuses on the VE process regarding the sheet pile bulkhead typical of many of the existing wharf structures in the Houston area. Because of predictable corrosion damage and high repair and maintenance costs for steel sheet pile bulkheads, a number of geotechnical and structural alternatives were considered. An initial screening study compared the relative merits of a steel bulkhead to five alternatives. Based on the results of the screening study, the tangent pier and Cement Deep Soil Mixing (CDSM) wall were selected for further analysis, with the Tangent Pier wall ultimately being chosen for detailed design. To further optimize the design of the drilled shafts, a full-scale vertical load test program was carried out. Three test shafts were constructed and tested in compression under loads as high as 9,786 kN (2,200 kips). The Bayport wharf is believed to be the first such marine structure in the U.S. to adopt the tangent pier concept as a means of enhancing slope stability. The tangent pier wall and associated precast bin wall proved to be less expensive than the steel bulkhead originally planned, and is expected to extend the service life of the structure by at least 30 years. Total savings to the project for a 50-year life are expected to be more than $10 million.