Glen Andersen, Sc.D., P.E., of Eustis Engineering will present a case study at the Louisiana Civil Engineering Conference and Show at 9:30 a.m. on Wednesday, 27 September. The title of his talk is “Stabilization of Mississippi River Bank Using Driven Pin Piles.”
Glen Andersen, Sc.D., P.E.
The presentation will focus on a Eustis Engineering project in which 3-ft. diameter pin piles were used to arrest an unstable slope that was causing distress to an industrial dock on the Mississippi River.
One of the key components of Eustis Engineering’s approach to this stabilization was to first look at the area’s geology and directly compare it to observed movement of the dock in order to determine the likely geometry of the slide planes.
“Understanding the local geology was crucial to understanding the behavior of the unstable riverbank,” Glen said. “The slide plane geometry was confirmed by visual observations from continuous undisturbed sediment samples and through field instrumentation.”
Eustis Engineering employed multiple modeling procedures to estimate the number and spacing of the pin piles required to stabilize the slope, including three separate types of L-Pile analyses, and 2D and 3D finite element modeling.
Using GPS-based monitoring stations, Eustis Engineering evaluated nearly real-time geotechnical instrumentation data for the design using an “observational method” approach. This data will continue to be collected over the next several years to demonstrate the slope has been stabilized by the pin piles installed.
“Simply estimating the loads being carried by the pin piles and using these to design the stabilization does not correctly address the way the piles and the surrounding soils actually contribute to the slope stabilization,” Glen said. “Based on our field measurements and engineering analyses, the pin-pile-only evaluation approach appears to significantly underestimate the stabilizing effect these have on the slope.” Sc.D.