Design, Construction, and Analysis of Fabric-Reinforced Embankment Test Section at Pinto Pass, Mobile, Alabama

摘要

Construction of earth embankments on soft foundations is often a different geotechnical engineering problem. Construction of a proposed confined dredged material disposal area for Mobile Harbor, Alabama, requires the U. S. Army Engineer District, Mobile, to construct approximately 6000 lin ft of 8-ft-high embankment on extremely soft cohesive foundation soils, with undrained shear strength from 50 to 150 psf. Approximately 50 percent of the alignment was in the intertidal zone. A factor of safety in bearing of approximately 0.4 to 0.6 was found to exist for conventional construction. The embankment would have to be raised an additional 17 ft during the 10 years after construction, and an additional 25 ft in the next 20 years. Fine, poorly graded sand was available nearby for use as borrow material in initial phases of dike construction. Nonengineering considerations dictated that the embankment be constructed with all deliberate speed and with minimal possibility of failure. After considering alternatives of preloading, use of lightweight construction material, and end-dumping displacement, it was decided to attempt construction of a civil engineering fabric-reinforced embankment along the alignment. The civil engineering fabric would be placed between the soft cohesive foundation and the sand embankment material in long, narrow strips perpendicular to the alignment, with the strips overlapped and sewn together. The fabric was postulated to act as tensile reinforcement, maintaining the embankment in a coherent mass, and partially supporting embankment weight until consolidation of soft foundation materials could occur. (Author)