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This study evaluates a novel biopolymer-based material reinforcement method. A real-scale experiment minimizing flood disasters and economic losses incurred by the collapse of river levees due to overtopping was conducted. At the Andong River Experiment Center, lateral overflow was reproduced to induce levee collapse using sand, reinforced novel materials, and vegetation levees represented as cases 1, 2, and 3, respectively. The flow in the upstream and downstream areas was measured, and fluctuations in the lateral overflow discharge were calculated using an acoustic Doppler current profiler. To quantitatively verify the performance of this method, the collapse delay effect based on the surface loss rate of the levee slope was analyzed using image pixel analysis and three-dimensional point cloud modeling. Comparing the collapse delay effect of the new-material levee with that of the non-reinforced levees, we found a time delay of approximately 2.7–7 times from the occurrence of overtopping via the lateral flow to the end of the test. These results indicate that we can secure time for emergency repairs and operations by reinforcing the levee surface using the material proposed in this study. These research findings are expected to provide the basis for the proper design and construction of river levees.

This study proposes an earthen levee reinforcement method with a new biopolymer-based material to prevent levee scour and breach. It is an eco-friendly method that can efficiently protect the levee slope as it enhances soil strength, even at a very low concentration of biopolymer, and has high resistance to surface runoff in addition to promoting vegetation growth. The function and effectiveness of this method were demonstrated through an overflow-based semi-scale experiment in a previous study. In this study, we examined the effect of biopolymer-mixed soil layer on levee stability against an overflow-induced breach. In these experiments, biopolymer-mixed soils were sprayed on the crest and land-side levee surface. Two full-scale tests were conducted (2.5&ndash, 2.7 m high and 14 m wide on bottom). Case 1 (control case) consisted of bare sand without any treatment, while Case 2 consisted of a 1.0% biopolymer-mixed soil sprayed on the crest and landside slope of the levee and turf put on it. By applying an image analysis technique, we analyzed the breach phenomenon and breach retardation effect of the levee treated with a biopolymer and covered with vegetation. In this experiment, the slope loss rate of Case 2 was retarded 1.5 to 2.3 times over time as compared to Case 1. During the experiment, we observed that soil erosion followed through the narrow water channel formed by the stripped turfs. This means that the grasses did not root firmly enough to protect the surface. In this regard, although the experimental results may seem unsatisfactory, the biopolymer was found to help improve erosion retardation. In 2020, we will conduct more experiments with different compositions and concentrations of the biopolymer regardless of levee vegetation. With this research, we expect to confirm that the new technology of using biopolymer-treated soils is promising for solving the levee overflow breach problem.

Cement and other similar compounds have been used to prevent a levee breach during a flood. However, the demand is increasing for eco-friendly and sustainable alternatives to replace the conventional method for levee stabilization and strengthening. To improve the durability and environmental friendliness of a levee, the Andong River Experiment Center applied a biopolymer, which is a new eco-friendly substance, to fabricate a levee model, and conducted a hydraulic model experiment to evaluate the reliability and stability of the new type of levee. An image analysis was applied to calculate the scale of the breaches of the levee slopes. Based on the experimental results obtained, the characteristics of the breach between an earthen levee and the proposed levee were compared. The stability of the levee body was also evaluated according to the thickness of the new substance. The ultimate aim of this study was to derive the optimal conditions by verifying the performance and effectiveness of the new substance in terms of levee breach factors such as overflow, seepage, or piping in a series of hydraulic experiments. In the future, the field application of these optimal conditions will be verified through a real-scale experiment.

Ko, D.; Kang, J., and Ryu, Y., 2019. Experimental study on relation between breach process and velocity distribution on levee due to overflow. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 16-20. Coconut Creek (Florida), ISSN 0749-0208.Coastal levee is an defensive structures important in low-lying coastal areas prone to floods, but is vulnerable to overflows when water levels increase extremely. Due to storm surge and high waves, water overflow and wave overtopping occur over coastal levee. Likewise, river levee is to protect lowland areas from floods. However, levee breaches due to aging of levees have caused huge damages on properties and human casualties. To advance as a society, it is essential to pursue meaningful implementations of solutions that prevent the erosion of levees during floods. To find a resilient structure of levee against overflow, this study has tested an environmentally friendly substance for reinforcing levee. With intent to testify the new method, a series of hydraulic experiments were carried out for to verify a flow state and surface velocity distribution according to levee breach progress by building a semi-prototype levee with a bottom width of 5 m, a slope of 1:2, a crown width of 1 m, and a height of 1 m in a 3 m bottom-wide natural channel. By building a measuring system using a number of imaging devices on site, the surface velocity distributions on the earthen levee and the levee reinforced with the new environmentally friendly substance were measured using a LSPIV technique. It is expected to be able to examine the characteristics of flow velocity distribution following breach processes on levees to evaluate the initial points of failure and the weak points during overflow.

Large construction companies in Korea are particularly interested in technical solutions for high-rise buildings. In particular they are looking for ways to maximise economy by reducing the dead load and increasing the height of storeys in buildings. To achieve this, a flat-plate system using high-strength lightweight concrete has been proposed. To solve the weakness of the brittle failure of lightweight concrete as well as punching shear of the flat-plate system, this study developed a new shear reinforcement method. According to the shear reinforcement method and pitch intervals of shear reinforcement bar, the new method was assessed according to the first cracking load (Pcr) and displacement (δcr), the maximum load (Pmax) and maximum displacement (δmax), ductility index, reserved shear strength, economic feasibility and ease of construction. The test results indicate that with the new method, the specimen showed better shear performance and ductility effect in high-strength lightweight concrete than in normal concrete. Compared to the existing shear reinforcement method, the new method enhanced both shear strength and ductility effect as the pitch interval decreased. The truss rail method was able to reduce the quantity required and the production costs, while also improving construction efficiency.