In July, 2006, a large embankment failure occurred during construction ofa four lane divided highway leading to the Canada/USA border crossing in St. Stephen, New Brunswick, Canada. The highway embankment was approximately 12.3 meters in height when it failed, just short of the design height of 14 meters. The cause of the failure was attributed to the rapid construction rate and intensity of loading on the low strength foundation soils consisting of up to 15 meters of soft marine clay. The reconstruction effort used 1.4 million scrap tires to make the Tire Derived Aggregate (TDA) as lightweight fill. TDA was placed within the new embankment, constructedover the site of the original failure. An important element to the design was the installation of geotechnical instrumentation, which allowed an observational approach to be undertaken. This approach resulted in modifications to the original design throughout the TDA embankment reconstructionprocess. This paper presents the results of the TDA embankment and foundation performance over a 25 month period, with emphasis on the design and behavior of the TDA during construction. Predicted versus field measured geotechnical parameters and performance of TDA are presented, including unit weight, temperature, immediate compression, and time-dependent compression. These measured parameters are compared to similar case histories and published values available from the literature. The TDA embankment reconstruction project began in the summer of 2007, and was successfully completed in late fall of 2008.
Samenvatting