Overtopping breaching of river levees constructed with cohesive sediments

Abstract

Abstract. Experiments were conducted in a bend flume to study the overtopping breaching process and the corresponding overflow rates of river levees constructed with cohesive sediments. The river and land regions were separated by the constructed levee in the bend flume. Results showed that the levee breaching process can be subdivided into a slope erosion stage, a headcut retreat stage and a breach widening stage. Mechanisms such as flow shear erosion, impinging jet erosion, side slope erosion and cantilever collapse were discovered in the breaching process. The erosion characteristics were determined by both flow and soil properties. Finally, a depth-averaged 2-D flow model was used to simulate the levee breaching flow rates, which is well expressed by the broad-crested weir flow formula. The deduced discharge coefficient was smaller than that of common broad-crested rectangular weirs because of the shape and roughness of the breach.

Overtopping induced failure of noncohesive, homogeneous fluvial dikes

“…[] and Frank and Hager [] for frontal dike experiments with a falling reservoir water level. The emerged part of the breach sides is steeper because the sand particles are sealed by apparent cohesion induced by negative pore water pressure [ Wei et al ., ]. The side slope angles (from 41° to 59° for the Test 8) exceed the angle of repose of sediment (φ sand ≈ 33°).…”

Overtopping‐Induced Failure of Non–Cohesive Homogeneous Fluvial Dikes: Effect of Dike Geometry on Breach Discharge and Widening

“…Charrier (2015), Wei et al. (2016) and Wu et al. (2018) studied the failure of dikes made of cohesive material.…”

A Soil Tensile Strength Based Headcut Migration Model of Breach Side Slope

“…Because of the erosion at the foot of the embankment, an overhanging soil block (called headcut) was formed that eventually collapsed. The breach of embankments became wider as the episodic failure of the headcut [9,10]. It is the headcut migration of the breach side slope that contributes to the breach widening.…”