scholarly journals Investigating the Effects of the Block Geometries and Sidewall Divergences on the Local Scour Downstream of Baffled Chute Spillways

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Morteza Karimi Chahartaghi ◽  
Sohrab Nazari ◽  
Mohsen Solimani Babarsad
Keyword(s):  
Flow Characteristic ◽  
Construction Cost ◽  
Maximum Depth ◽  
Bureau Of Reclamation ◽  
Trapezoidal Shape ◽  
Scour Hole ◽  
Scour Hole Dimensions ◽  
Hole Dimensions ◽  
Baffle Block ◽  
The U.S

Due to the lack of any specific study about the sidewalls and other blocks’ changes in the case of hydraulic and scour downstream, the present study was conducted to investigate this issue. For this purpose, drainage projects and spillway chutes, as well as many baffle block chutes, were designed and constructed with the parallel sidewalls and trapezoidal shape using the U.S. Bureau of Reclamation (USBR) instructions. Three divergence ratios of b 1 / b 2 = 1.45 , 1.75 ,   and   2.45 , a parallel sidewall of b 1 / b 2 = 1 , and also three geometry blocks including trapezoidal USBR, trihedral, and semicircle blocks were applied and tested in the hydraulic laboratory using a baffle chute with the slope of (2 : 1), (H : V). The material used in this study was sediment sand with a uniform grain size of d50 = 1.2 mm, 15 cm of thickness, and 2 m of length. The experiment was conducted with seven different discharges in lasting condition, and the flow characteristic and scour hole dimensions were measured. The results revealed that in comparison with the USBR blocks, changes in the baffle sidewall and block shape made an approximate 50% reduction in the maximum depth of the scour hole. Thus, increasing the divergence ratio from 1 to 2.45 had a significant effect on reducing the maximum depth and the topographic shape of the scour hole. According to the range mentioned in the literature for the Weber number, the scale effect was negligible for the chute with baffle blocks. Generally, it can be concluded that the sidewall changes also can make a reduction in the number of overbaffle blocks, causing a reduction in the construction cost.

scholarly journals The effects of splitters on the downstream scour hole of overflow spillways: application of support vector regression

2021 ◽  
Author(s):  
Mohammad Ehsan Asadi ◽  
Seyed Taghi Omid Naeeni ◽  
Reza Kerachian
Keyword(s):  
Support Vector Regression ◽  
Experimental Models ◽  
Data Driven ◽  
Support Vector ◽  
Method Performance ◽  
Statistical Measures ◽  
Proposed Model ◽  
Scour Hole ◽  
Scour Hole Dimensions ◽  
Hole Dimensions

Abstract One of the most effective ways to reduce the water jet erosion power during dam overflow is to use splitters on the lower side of spillway. The dimensions of scouring holes and their location in the dam basin should be accurately determined. Experimental models and data driven techniques can be effectively used for estimating the dimensions of scouring holes. The focus of this paper is evaluating the effects of splitters on the downstream scour hole of overflow spillways and providing an optimized splitter configuration. The Support Vector Regression (SVR) method performance in predicting the scour hole dimensions and its location downstream of the dam has been examined using 116 experimental data. In order to evaluate the efficiency of the proposed model, we used different statistical measures. The results show that the presence of splitters decreases the slope of downstream scouring in all situations. It is also shown that the SVR method can accurately estimate the dimensions of the scour hole and its location.

scholarly journals The relationship between the coefficient of discharge and the scour hole depth generated due to the combined flow over weir and below gates

2018 ◽  
Vol 162 ◽  
pp. 03010
Author(s):  
Saleh Khassaf ◽  
Hassan Omran ◽  
Fadhel Abdulabbas
Keyword(s):  
Median Size ◽  
Two Samples ◽  
Scour Hole ◽  
Combined Structure ◽  
Scour Hole Dimensions ◽  
Coefficient Of Discharge ◽  
Size Of Particles ◽  
Hole Dimensions ◽  
The Relationship ◽  
Laboratory Models

In this research, a study was conducted experimentally to investigate the scour hole dimensions downstream the combined structures which consist of weir and gate due to the effect of the coefficient of discharge (Cd) due to flow above the compound weir to the flow under the gate. Fifteen models have been designed, and every model is formed from composite weir consisting of two geometric shapes with rectangular gate of constant dimensions. In this study, the experiment was conducted in a laboratory channel was constructed from blocks and concrete with length of 18 m, 1 m width and depth of 1 m, where the laboratory models were installed after 7 m from the main gate which controlled the passage of water from the main reservoir into the flume. At the beginning, the calibration process was conducted to identify the actual discharge values that pass in the flume, and then seventy-five experiments were conducted in order to derive the formulae for investigating the non-dimensional depth (SD/d50) and non-dimensional length (SL/d50) of the scour hole due to the effect of (Cd). The bed of the flume was spread with sand layer of 30 cm thick for a distance of 4 m downstream combined structure. Two samples of sand were used in the experiments with different median size of particles (d50), the first of 0.7 mm and the second of 1 mm. Using the Excel program 2017, Six polynomial relationships were derived to calculate the dimensionless scour depth (SD/d50) in terms of the coefficient of discharge (Cd), where the resultant coefficients of determinations (R2) from these relationships were high.

The effect of pile spacing and arrangement on bed formation and scour hole dimensions in pile groups

2017 ◽  
Vol 15 (2) ◽  
pp. 219-225 ◽  
Author(s):  
Nina Solaimani ◽  
Ata Amini ◽  
Hossein Banejad ◽  
Pezhman Taherei Ghazvinei
Keyword(s):  
Pile Groups ◽  
Pile Spacing ◽  
Scour Hole ◽  
Scour Hole Dimensions ◽  
Hole Dimensions
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