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The characteristics of a novel environmentally friendly countermeasure against bridge abutments scour depth

Shafai Bejestan Mahmood, Raee Narges, Azizi Reza

Acta Geophysica

2024

Vol. 72, no. 1

357--369

Destruction of many bridges around the world has been found to be due to the collapse of its abutments owing to the formation of scour. Various methods have been proposed so far to reduce the scour depth, and in this study, a new and environmentally friendly method, namely triangular vanes made with six-pillar concrete (TV-SPC) elements, has been experimentally studied. For this purpose, various experiments were carried out without and with installing the TV-SPC at different distances (0.5L, 1L and 1.5L in which L = abutment length), three different lengths, in different rows (single, double and triple) and under two different hydraulic conditions. At the end of each experiment, the bed topography around the abutment was measured and the maximum scour depth and its location were extracted. The results show that for better performance, the TV-SPC should be attached to the bank at distance of 0.75L or 1 L . The longest TV-SPS found better to reduce the scour depth. A single L-TV-SPC installed at 0.75L upstream of the abutment can result in 68% and 78% scour depth reduction at high and low flow conditions, respectively. The reduction in scour depth can be increased up to 82% by installing three rows of TV-SPC.

Scour around spur dike in curved channel: a review

Tripathi Ravi Prakash, Pandey Kamlesh Kumar

Acta Geophysica

2022

Vol. 70, no 5

2469--2485

A spur dike is a hydraulic structure, protruding in a river or channel used for several purposes like protection of river-bank erosion and deepening of the main channel. The present paper discusses pre-existing research work on flow pattern and prediction of temporal and maximum scours depth around the spur dikes placed in different locations at 90◦ and 180° curved channels. The equations having approximately 2.367, 4.47, 0.17, and 0.271 (average) times with their corresponding experimental data. The parameters, influencing the scour process and flow pattern, have been identified as the ratio of flow intensity to critical velocity (V/Vc≥1) is below 1 and special kind of bedding material is approximately 10 % greater than under livebed condition and many more. The numerical value of the Froude number and the geometry of the bed surface material are also discussed in this paper. Based on these parameters, the empirical formulations and experimental studies on local scours around the straight, L-shaped, T-shaped spurs, placed at 30°, 45°, 60°, 120°, and 180° azimuthal angles have been discussed. Various numerical schemes proposed in almost seventy-five literatures have been summarized. A critical review of numerical and experimental results found in different works related to temporal and maximum scour depth, flow characteristics, and bed topography around the dike shows that the data and accompanying results are insufficient for the design of spurs used as river structures in curved channels. There are needs to carry out extensive experiments, under various flow conditions, to examine the flow behavior and scouring processes around the spurs. Due to complex flow pattern and scouring processes, taking place around the spur, it becomes difficult to understand the real physics behind these phenomenon and therefore, data-driven models are suggested to arrive at more reasonable relationships required to be used for design purposes.