2018-19 DFI Traveling Lecture at ASCE Seattle Section Geotechnical Group & Geo-Institute – Seattle Chapter September Dinner Meeting
September 26, 2019 – Seattle, WA
Executive Inn by the Space Needle
The 2018-2019 DFI Traveling Lecturer John R. Wolosick, P.E., D.GE, F.ASCE delivered his presentation on Stabilization work from Normandy Beach in France at Pointe du Hoc.
During World War II, after the occupation of France, the German army set up a ’Ragelbau’ Observation Post (OP) and large, long range guns at Pointe du Hoc in Normandy to rebuff any Allied invasion and to ward off Allied ships from the northern coast of France.
On D-Day, June 6, 1944, an Army Ranger battalion, led by Colonel James Earl Rudder, was tasked with taking Point du Hoc. It was a tough battle, with about 100 Rangers losing their lives while scaling the cliff and capturing the remaining Germans. The site is now a highly-visited landmark, with about 750,000 visitors per year. However, due to the harsh weather and rough seas in this area, the cliffs have receded about 10 meters since 1944. This erosion threatened the stability of the Observation Post, which had to be closed to the public due to the danger of its immediate proximity to the precipice. A team led by Texas A&M University and Dr. Jean-Luis Briaud was charged by the site owner, the American Battle Monuments Commission (ABMC), to investigate the stability of the cliffs and the OP. Texas A&M has a close association with the site, since Colonel Rudder was later the president of the University from 1959 until his death in 1970.
The team performed geotechnical and geological investigations, recommended fixes with cost estimates and established instrumentation to monitor the OP and the cliff. The presentation presented the history of the site along with the results of the investigation, repair recommendations and the final construction, which was designed and performed by French engineers and contractors. The repairs implemented included rock bolting with stainless steel netting, tieback anchors, micropiles, a few horizontal drains and special stone masonry. A reinforced concrete grade beam was built around the OP to transfer the stabilizing forces from the tiebacks and the micropiles into the cliff.