Abstract:
US Hwy 10, near the intersection of Sheyenne Street in West Fago, ND, has experienced documented slope movement since 2008, with evidence of slope movement dating as far back as 2002. Barr Engineering Co. (Barr) was contracted to prepare a design that would arrest the observed slope movement. Based on the results of limit equilibrium and finite difference modeling, Barr concluded that a driven pile system provided the most cost-effective solution.
Given that the nearest structures to the project were retail businesses and residential houses, minimizing the risk of vibration induced damage was critical for project success. Barr recommended maximum allowable peak particle velocities, and then estimated construction vibration levels using GRLWEAP (to estimate hammer input energy) and the relationship between hammer energy, and associated vibration levels, proposed by various researchers. The vibration modeling indicated that construction vibrations would likely be low enough that piles could be installed using impact driving methods, as opposed to alternate methods such as predrilled piles or drilled shafts.
To confirm that Barr’s estimates of vibration levels were reasonable, Barr coordinated with the North Dakota Department of Transportation to record vibrations for a separate pile driving project approximately 2.5 miles west of the Sheyenne River slope stabilization project and in a similar geologic setting. Barr installed seismographs at distances ranging from 50ft, to 800ft from the pile driving, to determine the vibration attenuation relationship. Barr’s predictions of maximum vibration levels showed good agreement with vibration levels recorded in the field.
Based on the results of Barr’s estimated vibration levels and field monitoring, Barr designed and executed a construction vibration monitoring program for the Sheyenne River project, consisting of eight seismographs, spaced over an 800ft radius from the pile driving operation.