Impacts of soil properties on bluff recession under combined waves and surge actions: An experimental study with uncertainty quantification

Abstract

Soil mixtures with five fines contents, two water contents, and two relative densities underwent soil mechanics tests to quantify their strength indices. Then small-scale steep beaches and bluff models were built with those soil mixtures in a small wave flume and subjected to varying water levels and waves. The equilibrium beach profile of the model containing a higher fines content, higher relative density, and the optimum water content, followed a concave down profile, while that of the models with the lower density and/or lower fines content, was concave up. The bluffs composed of the materials with the optimum water content exhibited a reduced crest recession compared to those with the constituent materials dry of optimum. The recession rate of the bluff crest decreased with the increase of the effective cohesion. For a given effective cohesion, the recession rate was significantly influenced by the relative density. The impact of the effective cohesion on the recession rate for the bluff composed of the looser soil was significantly greater than that of the bluffs with the denser constituent material. Furthermore, uncertainties associated with the impacts of the variations in the fines content, relative density, and water content on the recession rate were quantified.