Abstract
Flood damage has aggravated recently owing to artificial structures in high flow rare areas such as small rivers, which can lead to secondary damage. In this regard, studies are required to examine the conventional design criteria formulas to secure the stability of structures such as weirs and drop structures. Although studies on the stability of these structures have been conducted through small-scale experiments, few empirical studies have investigated the hydraulic phenomena occurring near actual artificial structures. In this study, we fabricated real-size models of weir and drop structure at the Andong River Experiment Center and investigated the flow patterns around the structures by applying the particle image velocimetry analysis technique with a flow tracker. We also measured the scour length in the waterspout section when the structures are overflowing, and compared it with the values calculated using the formula. Consequently, as the supply flow increases, the result is different from the value calculated using the formula given in the existing design standard, and it is judged to be inappropriate for a small stream area with high flow rate. Thus, it is necessary to consider the design factors such as energy gradient and the flow amount per unit width into weir and drop structure as well as the existing design factors in designing an apron section for a weir and drop structure.
Highlights
It is crucial to evaluate the stability of the design section in a weir and drop structure design for determining the stability
According to the change in the flow amount, the flow rate significantly increased near the weir and the drop structure and during the passing of the flow through the structure. This is because the total energy of the water flow increased with the change in the flow amount. This study compared both the formula given by the National Construction Research Institute, as in (1), and Bligh’s formula, as in (2), presented in the River Design Criteria [9] with the scour length measured through the real-scale weir and drop structure experiments
According to the results of comparison with the formulas presented in the River Design Criteria, when the flow amount per unit width is 0.25, it can be observed that both the formula given by the National Construction Research Institute and Bligh’s formula are distributed within the allowable threshold
Summary
It is crucial to evaluate the stability of the design section in a weir and drop structure design for determining the stability. The stability of weirs and drop structures is evaluated in South Korea in terms of overturning, activity, and settlement. Japan specifies that the stability evaluation for the design of weirs and drop structures should be based on overturning, activity, and settlement. The current domestic River Design Standard provides only the regulations for the design segment and the shape in the design of weirs and drop structures, while specifying no criteria for external force and internal force calculation for each stability evaluation item. It is difficult to determine how stable the currently installed weirs and drop structures are against floods
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
