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1

Assessment of submerged floor water jets to minimize the scour downstream from a stepped spillway

Ibrahim Mohamed M., Diwedar Al Sayed Ibrahim, Ibraheem Ahmed Mahmoud

Journal of Water and Land Development

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2021

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no. 50

122--129

EN

Because of hydraulic jump, the scour downstream a stepped spillway is the most confusing issue that endangers the overall stability of the spillway. In this paper, thirty-six exploratory runs are described to explore the impact of utilizing submerged water jets fixed in the stilling basin of a stepped spillway on the downstream scour measurements under various flow conditions. A smooth apron where the water jets are disabled is incorporated to characterize the impact of adjustments studied. Trials are performed utilizing different upstream discharges, jets arrangements, and tailwater depths. The results are analyzed and graphically presented. The experimental data are contrasted to a scour formulae developed by other specialists. Outcomes indicated that by utilizing submerged floor water jets, the maximum scour depth is decreased between 14.3 and 36.0%. Additionally, the maximum scour length is reduced by 9.7 to 42.3%. Finally, involving regression analysis, simple formulas are developed to estimate different scour parameters.

2

Prediction of scour depth around bridge piers in tandem arrangement using M5 and ANN regression models

Rahul M., Baldev S.

Archives of Materials Science and Engineering

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2020

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Vol. 102, nr 2

49--58

EN

Purpose: Due to an increase in a number of bridges being constructed, scour depth around bridge piers is gradually being recognized as one of the possible reasons for bridge failure. According to [1] about 53% of bridge failures in the US were caused due to floods and corresponding scour in the rivers. Lots of work has been carried out around the single pier but in the case of group piers, the work is very less. Hence, it becomes necessary to calculate the actual scour depth around the bridge piers considering the close location of bridges as well. Design/methodology/approach: Recognizing the need for research in this direction, an experimental study was planned and conducted in the Hydraulics Laboratory of Civil Engineering Department of National Institute of Technology Kurukshetra, India. Experiments were conducted in a standard recirculating tilting bed water flume 15 m long, 0.4 m wide, and 0.60 m deep. The orientation of more than one pier, namely Tandem pattern was employed for the work. Two pier models, 62 mm and 42 mm diameter were used for the experimental study. The mobile bed used in the experiments had an average mean size, d50 = 0.23 mm, 0.30 mm and 0.50 mm. Findings: The outcomes of the ANN function and M5 model analysis have been used to compare with experimental results. From the earlier studies, it was concluded that, when the clear spacing between the pier models was greater than 0D the scour depth around the piers increase with a rapid rate. However, in the case of modelling techniques, M5 models show higher predictive accuracy than ANN models. Research limitations/implications: It is a significant area of research. However, the present study has been a time and facility- constrained study. Therefore, there is a large scope to conduct further studies on the subject, Different pattern i.e. Side by Side; Staggered and Group of piers can be adopted for further investigations. Originality/value: Sufficient work has been done by number of researchers around the single bridge pier. But due to rapid urbanization a number of bridges constructed in close proximity to each other which affects the scour depth of each other. Modelling techniques used in hydraulic engineering are not always effective in practice. The present study discusses the effect of spacing on scouring around piers in a tandem arrangement using experimental as well as modelling techniques. To predict the scour depth of the Tandem arrangement 89 laboratory data sets have been used.

3

The influence of sandy clay bed material to local scour behaviour

Rustiati N. B., Dermawan V., Rispiningtati, Limantara L. M.

Journal of Water and Land Development

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2017

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no. 35

193--202

EN

As a type of gate that is used to control the water level upstream, sluice gate is the gate with simple shape and outstanding ability to flush the sediment. The operation of the gate is considered an important process. The up and down movement of the gate would affect the velocity and cause local scour as the result of fluctuating rate. This research aims to assess the effects of discharge and gate-opening height variations, as well as the type of bedchannel material, on the change of depth of scour (ds). The research was conducted of open channel flow model with a sluice gate able to up and down movement. The discharges used in the research were 9 types ranging from 1.0 to 5.0 dm3·s–1. There were 5 variations in the height of gate-opening ranging from 0.5 to 2.5 cm at intervals of 0.5 and types of channel-bed material. The results of the research showed that the depth of scour can be analysed as a function of discharge, height of gate-opening, height of water level upstream and downstream, and the type of bed material used. The scour depth equation is ds=1.7822(Q/a )1.1347 a. Calculated coefficient of determination of the relationship between two types of channel-bed material and the depth of scour was R2 = 0.946. Consequently, it can be concluded that the equation can be applied on both types of bed-channel material.

PL

Wrota śluzy o prostym kształcie i wyjątkowej zdolności do przemywania osadu są urządzeniem do kontrolowania poziomu wody powyżej śluzy. Ważnym procesem jest sposób operowania wrotami. Ruch wrót w górę i w dół wpływa na szybkość przepływu i powoduje lokalne rozmycie dna. W badaniach prezentowanych w niniejszej pracy oceniano efekt odpływu i zmiennej wysokości otwarcia wrót oraz typu materiału podłoża na głębokość rozmycia (ds). Badania prowadzono na modelowym, otwartym kanale przepływowym z wrotami śluzy o ruchu pionowym. Zastosowano 9 prędkości przepływu – od 1,0 do 5,0 dm3·s–1 i 5 wysokości otwarcia śluzy – od 0,5 do 2,5 cm w przedziałach co 0,5 cm oraz różne typy materiału podłoża. Wyniki badań dowiodły, że głębokość rozmycia można analizować jako funkcję odpływu, wysokości otwarcia śluzy, wysokości poziomu wody powyżej i poniżej śluzy oraz typu użytego podłoża. Otrzymane równanie głębokości rozmycia ma postać ds=1,7822(Q/a )1,1347a . Obliczony współczynnik determinacji dla zależności głębokości rozmycia od dwóch typów materiału podłoża wynosił R2 = 0,946. Można zatem wnioskować, że równanie może być stosowane do obydwu typów podłoża.

4

Prognoza deformacji dna poniżej bystrza o zwiększonej szorstkości i jej weryfikacja na podstawie wyników hydraulicznych badań modelowych

Ślizowski R.

Inżynieria Rolnicza

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2004

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R. 8, nr 2

165--173

PL

Praca ma na celu zbadanie, w jakim stopniu prognozowane wartości deformacji dna poniżej bystrzy wykazują zgodność z wynikami uzyskanymi na podstawie hydraulicznych badań modelowych. Przeprowadzono badania modelowe sześciu rozwiązań konstrukcyjnych bystrzy o zwiększonej szorstkości, określając głębokość maksymalną rozmycia hmax. W celu obliczenia prognozy deformacji dna wyznaczono parametry funkcji opisującej rozmycie dna. Do opisu modelu zastosowano regresję wieloraką, przy czym analizowano funkcję regresji przy czterech i siedmiu współczynnikach modelu. Zastosowanie dwóch typów funkcji miało na celu zweryfikowanie czy postać funkcji ma istotny wpływ na wartość współczynnika zgodności modelu z wartościami pomiarów na modelu hydraulicznym. Analiza i ocena wyników wykazała, że przy korzystaniu z modelu o siedmiu współczynnikach otrzymano korzystniejsze rezultaty obliczeń. Należy zaznaczyć, że różnice wyników obliczeń z wynikami z pomiarów, dla obydwu rozpatrywanych modeli (cztero- i siedmioparametrowego) są niewielkie i wynoszą około 10%.

EN

The paper is aimed at examining the predicted bottom deformation accuracy degree below rapids with results based on modeling studies. The hydraulic studies of six different constructional solution of rapids with increased roughness were carried out. The maximum scour depth hmax were measured. The predicted bottom deformation was expressed in the form of multiple regression with four and seven arguments of function. Applying the both type of function helped to verify whether the shape of function has significant impact on the accuracy coefficient between calculated and measured data. Analysis and its assessment showed out that the fitting with seven arguments of function gave better approximation. But it is to be said that for both models (with four and seven arguments) the differences are small and are about 10%.