Pan, Y.; Li, L.; Amini, F., and Kuang, C., 2013. Full-scale HPTRM-strengthened levee testing under combined wave and surge overtopping conditions: overtopping hydraulics, shear stress, and erosion analysis.
Post–Hurricane Katrina investigations revealed that most earthen levee damage occurred on the levee crest and landward side slope as a result of wave overtopping, storm surge overflow, or a combination of both. This study was conducted to investigate the hydraulic parameters and erosion characteristic of one levee strengthening technique, a high-performance turf reinforcement mat (HPTRM), under combined wave and surge overtopping conditions, about which little is known. Because the HPTRM system can only be tested using a full-scale model, a full-scale laboratory study on combined wave and surge overtopping of a levee crest and landside slope strengthened by the HPTRM was conducted in a two-dimensional laboratory wave/flow flume. The overtopping hydraulic features were summarized during the tests. The time series of flow thickness and velocity at five locations on the levee crest and landside slope were measured. Soil erosion and stem and blade loss were measured during the test intervals. New empirical equations were developed to estimate the average overtopping discharge. Based on the distribution of the overtopping discharge, combined wave and surge overtopping was divided into two cases: a surge-dominated case and a wave-dominated case. New equations were developed to estimate the mean flow thickness, root-mean-square wave height, mean velocity, and velocity of the wave front on the landside slope. The shear stress and average overtopping velocity on the landside slope and levee crest were calculated. The characteristics of soil loss and grass stem and blade loss on the HPTRM-strengthened levee were given. A “maximum soil loss” was found for each measuring point.