EVALUATION OF THE EFFECTIVENESS OF STRENGTHENING PAVED EMBANKMENT TOP AGAINST EROSION DUE TO NAPPE FLOW THROUGH EXPERIMENTS AND NUMERICAL MODEL ANALYSIS

Abstract

 Under the frequent occurrence of levee-breach by overtopping at flood events, it is necessary to develop an embankment that is hard to be breached. The overtopping water flows along the embankment slope at the beginning, but the flow gradually separates from the slope and becomes to ‘nappe flow’ which further hits and erodes the landside. This study focuses on the erosion phenomenon due to nappe flow by hydraulic experiments and numerical analysis and considers the effect of asphalt pavement on the top of embankment which is made of sandy material. When the nappe flow erodes the landside ground, a large scoured region is formed. The scour collapses the body of embankment, and the pavement on the top of embankment is lost along with the body, causing further erosion. To suppress the broke of the top pavement, it is effective to strengthen the pavement with grid material. This process can be reproduced by numerical model.