Twenty Years of Stone-filled Geosynthetic Mattresses – An Assessment of Performance and New Directions

摘要

Stone-filled geosynthetic mattresses, also known as marine mattresses, have been in use since the mid-1990’s. Initially mattresses were fabricated from high density polyethylene (HDPE) geogrid. To improve performance, the mattress geogrid is now a copolymer of High Density Polyethylene (HDPE) and Polypropylene (PP). The mattresses are fabricated into a variety of shapes that are generally rectangular (5 or 6.5 feet wide and 10 to 45 feet long) with thicknesses ranging from 6 to 24 inches. The mattresses have interior baffles to keep the stone at the specified density within each compartment. The projects to be discussed are indicative of the expanding range of marine applications. In most applications, marine mattresses are subject to direct wave forces and high shear stresses due to high velocity water flow. Generally, the function of the marine mattress is to increase the foundation strength or provide scour and erosion protection, or both. They also serve the function of a filter layer by separating the upper layer of stone from the foundation material. In recent years, design approaches and tools have been improved, based partly on testing at Colorado State University.rnThree of the earliest marine mattress projects will be assessed for their performance over the past 20 years. The projects include the runway extension at Logan International Airport, a riverbank protection project in Newnan, GA, and T-groin foundations at Tybee Island, GA. The project at Cape May Point is a 450 linear foot marine mattress revetment. This revetment was installed in 1995 by the New Jersey Department of Environmental Protection. The 50 year design wave height is listed as 22.6 feet by the USACE (1997). Additionally, lessons learned from projects in Salt Lake City, Atlanta, Georgia and Puerto Rico will be presented.