In Situ Geotechnical Investigation Of Nearshore Sediments With Regard To Cross-Shore Morphodynamics

Sediment dynamics cause continuous changes in nearshore morphology and play a major role in coastline evolution as well as for engineering activities in the coastal zone. A portable, free-fall penetrometer was used to investigate the geotechnical characteristics of surficial seabed sediments in the energetic nearshore zone of the U.S. Army Corps of Engineers Field Research Facility at Duck, NC. Penetrometer deployments were carried out along four cross-shore transects in water depths of 0.8-14.3 m. Duplicate deployments demonstrated the reproducibility of the results. The derived maximum quasi-static bearing capacities ranged from 8.7-251 kPa, with a decrease in the qsbc and in the scatter in the seaward direction. Significant differences in sediment strength were observed in the vicinity of the actively migrating, shore parallel sandbar. The study shows a strong relationship between geotechnical characteristics and active morphodynamics of the nearshore seabed. The depth of closure was reflected in the penetrometer results.