International Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 04, April 2019, pp. 2006-2022, Article ID: IJCIET_10_04_209
Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=04
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
Scopus Indexed
MINIMIZING OF SCOUR DOWNSTREAM THE
OUTLETS OF THE BOX CULVERT
Abdel Aal G.M., Elsaiad A.A., Elnikhely E.A. and Zaki E.M*
Water and Water Str. Eng. Dep., Faculty of Engineering, Zagazig University, Zagazig, Egypt
*Corresponding author
ABSTRACT
Local scour downstream the box culverts outlet may cause to a complete failure of
the culvert structure. New research is employed to reduce the max scour depth
downstream the outlet of the box culvert under a different flow conditions based on an
experimental investigation. A sharp edge sill is proposed on a rigid bed to dissipate the
flow excess energy. Consequently, a great reduction of the scour hole dimensions is
obtained by using the sharp edge sill. The experimental study was carried out using a
different positions, heights and shapes of the sharp edge sill with different flow rates as
well as tail water depths too. The results indicates that the sharp edge sill is a promising
tool to reduce the scour dimensions. The reduction of the scour depths by using the
sharp edge sill are 60%, while the reduction in the scour depths are 64%,that is because
of using of rigid apron of length 7 times the height of culvert, compared to previous
results without rigid bed.
KEY WORDS: Scour, culvert, culvert outlet, sill, submerged ratio, tailwater depth.
Cite this Article: Abdel Aal G.M., Elsaiad A.A., Elnikhely E.A. and Zaki E.M,
Minimizing of Scour Downstream the Outlets of the Box Culvert. International
Journal of Civil Engineering and Technology, 10(04), 2019, pp. 2006-2022
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1. INTRODUCTION
Culverts are covered man-made channel that conveys water below roads, railways, or any other
structure. The flow mean velocity measured inside the culvert's barrel is higher than the
velocity measured at the upstream due to the contraction of the flow section area in the barrel.
Upon exiting of the culvert’s barrel, scour can occur if no suitable protection or energy
dissipation structure is provided. Abt et al [1] studied the effecting of the culvert slope on scour
depths at the outlets and they mention that the sloped culvert increased the scour depths up to
40% more than the scour dimensions for the horizontal culvert. Abt et al [2] studied the
effecting of culvert shape on scour depth at the outlet of culvert and noticed that the dimensions
of scour for the circular culverts significantly varies of other culvert shapes. Negm et al.[3],
used a flow deflector to reduce scour dimensions at the pipe outlets under different flow
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conditions. The results mentioned that the flow deflector was a promising tool to reduce the
scour dimensions. The reduction of the scour depth by using the flow deflector was 68%, while
the reduction in the scour depth was 80%, due to using a rigid apron of length 7 times the pipe
diameter, compared to the previous results without rigid bed. Osman et al.[4], founded that the
semi-circular apron gave less scour depth and width when compared to the linear front apron.
The comparison of the outputs of the model and the field study was found of a good agreement.
The model was recommended for engineering design of drainage structures located on streams
of sandy bed. They developed an equation for prediction the scour depth at the outlet of the
culvert. Liriano et al. [5], studied the effect of the turbulent flow on the culverts outlet scour
and mentioned that the length of the scour depth for the fully developed scour hole coincide to
the high values of turbulence intensities on the fixed bed. Hotchkiss et al[6], studied the
effecting of the hydraulic jump geometry and the effectiveness of the hydraulic jump on the
outlet scour.. Hotchkiss and Larson [7], used two alternatives to dissipate the flow energy at
the outlet of the culvert. Abida and Townsend [8], studied the effecting of the tailwater depth,
the passing discharge and the cross-section area on the scour dimensions. Many developed
empirical equations– see [3] ,[8],[9],[10],[11],[12],[13],[14],[15],[16],[17]– were depend on
experimental studies to predict and calculate the scour depth under specified flow conditions.
Equation (1) is one of the famous equations, which was founded by Ruff, et al., [18]
d sc ws d d
v
 
,
,
, s3  C s C h ( 1 , 

Rc Rc Rc Rc
3 

Q
2.5
g Rc
  t 
 ,
  316 


(1)
In which, 𝑑𝑠c is the scour depth, 𝑤𝑠 is the scour width, 𝐿𝑠 is the scour length, 𝑉𝑠 is the scour
volume, 𝑅𝑐 is the culvert end's hydraulic radius, Q the flow discharge, g is the gravitational
  D84 / D16
acceleration, t is the duration of scour in minutes,
, Cs, Ch, α, β, θ are
coefficients.
Bohan [19]as reported by Ruff, et al., [18]performed some scour experiments for flow for
pipe culvert on sand material with d50=0.22 mm and put the following equations.
d sc
 t 0.1 (1.3  1.4 log Fo )
D
(2)
Lsc
 4t 0.15 (1  5 log Fo )
D
(3)
in which: 𝐹𝑜 is the Froude number. Fletcher and Grace [20]as reported by Ruff, et al.,
[18]extended bohan's works. Actually, some conclusions were presented including that; the
parameter 𝑄/𝐷2.5 was a significant parameter. The following equation was developed.
d sc
Q
 0.74( 2.5 ) 0.375 (t ) 0.15
D
D
(4)
Crookston et al [21] reviewed some empirical formulae for the prediction and caculation
of the maximum scour depth at culvert outlet. Doehring and Abt [22] studied the effectting of
the drop height on the localized scour at the culvert outlet. Abt et al. [11]and Chiew and Lim
[23], developed two empirical equations to calculate the scour depth, see equations (1) and (2)
respectively.
𝑑𝑠c/𝐷 =−3.67 (𝐹𝑜 0.57𝐷50 0.4
𝜎 −0.4)
(5)
𝑑𝑠c/𝐷 = 0.21𝐹𝑜
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Minimizing of Scour Downstream the Outlets of the Box Culvert
Chen et al. [24], studied the effecting of several energy dissipation structures for reducing
the scour depth at the culvert outlets and founded that the combination of the low sill and a
drop is the effective way for dissipating energy. Crookston and Tullis [25], studied the outlet
scour for the culvert streambed stability using a 0.61m diameter arch culvert. The observations
regarding the location and extent of scour events were discussed. Elfiky et al.[26], studied the
effecting of the angled deflector on the local scour downstream of regulators. It was mentioned
that locating the deflector within the first quarter of the stilling basin downstream of the piers'
end gave the best performance. Helal et al.[27], reduced the max scour depth downstream the
hydraulic structures using sills. Also, they noticed that for most considered values of sills
height, the case of fully silled floor gave the smaller values of scour parameters. Omara et
al.[28], they used a numerical model of FLOW-3D for predicting the scour depths around the
pier. The model provided a good estimation of water levels, flow velocity and bed shear stress.
They mentioned that a 3D hydro morphological model can be effectively used to predict and
estimate the scour depth around piers. Fahmy[29] studied the scour depths at the pipe culvert
tail escape outlet and developed and verified an empirical equations to be used to compute the
scour depth and scour length downstream tail escape.
There are studies on the culvert blockage during flood. As an example, Rigby et al[30]
studied the blockage of culverts in the flood. They discussed causes and effects of culvert
blockage. Rigby & Barthelmess [31] explored culvert blockage mechanisms and their impact
on flood behavior. They noticed that one of the consequences of blockage culvert being the
flow diversions caused by blockage of culvert. Sorourian et al. [32], studied the effecting of
the blockage ratio and flow conditions on the scour depth at the outlet. It was mentioned that
the maximum scour depth increased in partially blocked condition compared to the nonblocked condition. Tan and Sheau Maan [33], used a 3D full flowing horizontal jet scour to
simulate and modelling the culvert scour in laboratory condition. They mentioned that the nondimensionalized scour depth can be expressed as d as 𝑑𝑠𝑒/𝑅ℎ = 1.22𝐹𝑜,84. where the dse is
the and Rh is The hydraulic radius, (Fo,d84) a modified densiometric Froude number, and d84
= d50*σg. Najafzadeh[34] used the neuro fuzzy-based group method of data handling to
predict and estimate the scour depth at the conditions of equilibrium at the culvert outlets.
Tjahyana and Lasminto[35], simulated the change of width and depth of the channel bed of
box culvert on the same location and the same length in certain distance. There were three
variations of channel bed. The first was the initial dimension of the box culvert, the second is
the change of channel bed into twice wider than the initial width, and the third was the change
of channel bed into twice deeper than the initial depth. They used The SSIIM 1 program to
Simulation of Sedimentation Movement in Water Intakes. They found the second and the third
variation show that the location of sedimentation changes in line with the changes of width or
depth of the channel bed.
So, the aim of this experimental research is to reduce scour downstream the box culvert
outlets. The present experimental investigation focuses on the reducing of the scour hole
dimensions downstream of box culvert using a new approach based on a limited bed protection
provided with Sharp Edge Sill.
2. DIMENSIONAL ANALYSIS
The local scouring at the box culvert outlet depends on a large number of flow and material
variables as shown in figure (1). By applied the Buckingham' theorem to the variables affecting
the scour hole dimensions downstream the box culvert. The following assumptions are adopted:
the flow is steady and the temperature has a negligible effect on the results. Thus, the following
functional relationship is formed:
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Abdel Aal G.M., Elsaiad A.A., Elnikhely E.A. and Zaki E.M
𝑓 (𝜌, 𝜇, 𝑔, 𝑑𝑠c, 𝐿𝑠c, 𝑑𝑑, 𝐿𝑑, d50, b, y, v, y𝑡,𝐿sill,𝐻sill ,  sill )= 0
(7)
Selecting 𝜌, y, v as repeating variables, the following dimensionless equation is obtained:
d sc Ls d d Ld
y L
H
,
,
,
 f ( Fn , t , sill , sill ,  sill )
y
y
y
y
y
y
y
(8)
In which: dsc/y is the relative maximum scour depth; Lsc/y is the relative maximum scour
length; dd/y is the relative maximum deposition depth; Ld/y is the relative maximum deposition
length; Fo is the Froude number, yt/y is the relative tail water depth, Lsill/y is the relative
position of sharp edge sill in the flow direction, Hsill/h is the relative height of sharp edge sill .
3. EXPERIMENTS
Experiments measurements were carried out in the laboratory of hydraulics at the Faculty of
Engineering, Zagazig University, Egypt.
3.1. The flume
Experiments were carried out in a prismatic rectangular re-circulating flume. The flume has
the dimensions of 66 cm width, 65.5 cm depth, and 16.2 m length. The flume is equipped with
a tailgate to control the tail water depth at the culvert outlets. A rectangular calibrated weir
fixed at the end of the flume to facilitate the measuring of the passed discharge during the
experiment. The basin was made from a clear Perspex to enable visual inspection of the
phenomenon being under investigation. see figure 1
Figure. 1. General view of the laboratory flume
3.2. The experimental models
Box culvert made of clear Perspex was used as a crossing structure. The box culvert have a
dimensions of 34.65 cm width, 300 cm length, 11.55 cm height, slope of zero , the culvert
was followed by a solid floor of length 0.80 m, and 0.66 m width and made of marble, a
movable sand bed of length 4.0 m and 20cm thickness was formed just downstream of stilling
basin, which has a sieve analysis with d50 equal 3.8 mm see Figure (1), the expansion ratio for
experimental model (i.e. e = B/b) =1.90, where B is the flume width, the sills was fitted in the
rigid apron, the experimental tests were categorized in fourth sets as follow. (see table 1)
1. The first set of the experiments was carried out without any sill
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Minimizing of Scour Downstream the Outlets of the Box Culvert
2. The second set of the experiments was carried out using one semicircular sill. It
included three positions of sill where Lsill/y = 0.86, 2.6, and 4.3. For each position
of the height of the sill was constant,
3. The third set of the experiments was carried out using three segmental curved sill
(i.e 90 seg.curved sill ,120 seg. Curved sill and straight sill) with fixed height,
4. The fourth set of the experiments was carried out using the straight sill with
different relative height (i.e Hsill /y = 0.1, 0.2 , 0.3, 0.35 and 0.50).
3.3. The experimental procedures
After the flume was filled with bed material (marble) and accurately leveled, the leveling
accuracy was checked by means of a point gauge. The following steps were carried out for
each model but the first step not done for case of without sill:
a) The sill was fitted in the rigid apron with a certain height and position,
b) The tail gate was closed and back water feeding was started first until its depth
reached higher than the required tailwater depth at the flume,
c) The control valve of the pump was opened gradually until the required discharge
passing in the flume,
d) The discharge was measured by using the sharp crested weir at the end of the flume,
e) The tail gate was screwed gradually until the required downstream water depth was
arrived using the point gauge,
f) Start the time of the test,
g) After 4 hours (there is no change in bed profile), the pump was turn off,
h) The flume and the scour hole were drained from water slowly, the scour depths and
lengths were measured using point gauge.
Figure. 2. Definition sketch of the experimental model
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Table 1: Scheme of experimental work stages
Stage
description
Characteristics
Lsill /y Hsill /y
Selected photos
angle
Runs
1
the case of floor
without sill
0
0
0
5
2
the effect of the
sill position
0.86
2.6
4.3
0.35
90 seg. sill
12
3
the effect of the
shape in the
plan
90 seg.sill
3
the effect of the
height of the sill
0.86
0.35
0.86
0.1
0.2
0.3
0.35
0.5
120 seg. sill
(180 degree)
straight sill
straight sill
12
20
4. RESULTS AND DISCUSSION
Experimental tests were carried out to study the max scour depth and the scour hole geometry
downstream culvert outlet for different flow conditions.
4.1. Effect of using fixed apron on scour parameters
Figure 3 shows a comparison between the present experimental results and each of Negm et
al[3]. Ruff, et al[18]; Fletcher and Grace [20]and Bohan [19]. It shows the predicted values of
dsc/y and Lsc/y using Eqs. (1), (2), (3) and (4) versus the present measured results.
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2.5
d sc / y
2
1.5
Recent study
Negm et al (2014)
Ruff et al (1982)
1
0.5
(a)
0
0.65
.
0.7
0.75
16
0.8
0.85
Fn Culvert
0.9
0.95
1
0.95
1
14
L sc / y
12
Recent study
Negm et al (2014)
Ruff et al (1982)
Fletcher and Grace (1972)
10
8
6
4
2
(b)
0
0.65
0.7
0.75
0.8
0.85
Fn Culvert
0.9
Figure. 3 Agreement of Negm et al[3]; Ruff, et al[18]; Fletcher and Grace [20] and Bohan [19].
Equations with the experimental measurements (a)dsc/y (b)Lsc/y
The present experimental results are less than the other empirical equations by about 60 %
of Ruff [18] and near to the results of Negm [3]. The main reason is that, the outlet of the
culvert used in the previous authors' equations are directly rested on the movable bed. In
contrast, the recent experimental results used a rigid bed downstream the culvert outlet. Its
length is about 7-times the culvert height. A great portion of the flow energy is dissipated on
the rigid apron and hence the erosive action of the water is greatly reduced. Consequently, the
scour hole dimensions are significantly reduced. This would be of great importance with
significant engineering and economics benefit in engineering applications, as using rigid bed
with length of 7times the height of culver to reduce the scour by about 60 %.
4.2. Effect of Sharp edge sill on scour parameters
In order to reduce the scour dimensions at box culvert outlets, it is essential to realize the nature
of the phenomenon and the interaction between the flow and the proposed sharp edge sill (flow
deflector). The scour parameters 𝑑sc/y,Lsc/y,𝑑𝑑/y and 𝐿𝑑/y are assessed for the culvert Froude
number (Fn = 𝑉/√𝑔y); and three different characteristics of the sharp edge sill including the
position , the angle of curvature of the sharp edge sill and the sill height.
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4.2.1. The position of the sharp edge sill (Lsill/y)
Figure (4) shows the relations between culvert Froude number and the different parameters
including 𝑑sc/y,𝐿sc/y,𝑑𝑑/y and 𝐿𝑑/y for the different values of sharp edge sill's relative position
of (i.e., Lsill/y = 0.86, 2.60 and 4.30 as shown in figure 5). Generally, all scour and deposition
parameters are grow up as Fn increases and this matched well with the previous results [Negm
et al[3] and Ruff, et al.[18]]. In addition, the values of these parameters are reduced to their
least values for Lsill/y = 0.86. The case of Lsill/y = 0.86 decreases 𝑑sc/y,𝐿sc/y,𝑑𝑑/y and 𝐿𝑑/y by
64%, 78%, 97% and 94% compared to the base case.
0.8
without sill
L sill/y = 0.86
L sill/y = 2.60
L sill/y = 4.30
0.7
d sc / y
0.6
0.5
0.4
0.3
0.2
0.1
(a)
0
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
Fn Culvert
5
without sill
L sill/y = 0.86
L sill/y = 2.60
L sill/y = 4.30
L sc / y
4
3
2
1
(b)
0
0.65
0.7
0.75
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0.8
0.85
Fn Culvert
2013
0.9
0.95
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1.2
1
dd /y
0.8
0.6
without sill
L sill/y = 0.86
L sill/y = 2.60
L sill/y = 4.30
0.4
0.2
(c)
0
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
0.9
0.95
1
Fn Culvert
12
without sill
L sill/y = 0.86
L sill/y = 2.60
L sill/y = 4.30
Ld /y
10
8
6
4
2
(d)
0
0.65
0.7
0.75
0.8
0.85
Fn Culvert
Figure. 4 Relations between Fn and the different scour parameters for different sill positions (Lsill/y)
(a) dsc/y ,(b) Lsc/y ,(c) dd/y and (d) Ld/y
Figure. 5 show the position of the sharp edge sill
4.2.2. The shape of the sharp edge sill in the plan veiw
Figure (6) shows the relations between culvert Froude number (Fn) and both of scour and
deposition characteristics for the different shape of the sharp edge sill in the plan view (straight
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sill, 120 segmental curved sill and 90 segmental curved sill) as shown in the figure (7). The
case of straight sill compacted the different scour parameters dsc/y and Lsc/y compared to the
initial case by about by 79%, and 92%, respectively. Moreover, it decreased the deposition
parameters dd/y and Ld/y by 80% and 54%, respectively.
0.8
without sill
90 seg. curved sill
120 seg. Curved sill
straight sill
0.7
d sc / y
0.6
0.5
0.4
0.3
0.2
(a)
0.1
0
0.65
0.7
5
0.8
0.85
Fn Culvert
0.9
0.95
1
without sill
90 seg. curved sill
120 seg. curved sill
straight sill
4
L sc / y
0.75
3
2
(b)
1
0
0.65
0.7
0.75
0.8
0.85
Fn Culvert
0.9
0.95
1
1.2
dd/y
1
0.8
without sill
90 seg. curved sill
120 seg. curved sill
straight sill
0.6
0.4
(c)
0.2
0
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
Fn Culvert
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12
without sill
90 seg. curved sill
120 seg. curved sill
straight sill
Ld/y
10
8
6
4
(d)
2
0
0.65
0.7
0.75
0.8
0.85
Fn Culvert
0.9
0.95
1
Figure. 6 Relations between Fn and the different scour parameters for different sill positions (angle of
sill) (a) dsc/y ,(b) Lsc/y, (c) dd/y, (d) Ld/y
Figure. 7 show the angle of the sharp edge sill in the plan veiw
4.2.3. The height of the sharp edge sill (Hsill/y)
Figure (8) shows the relations between Fn and both of scour and deposition characteristics for
the different sharp edge sill's relative heights (0.10,0.20,0.30,0.35 and 0.50). The case of
hsill/y=0.35 compacted the different scour parameters dsc/y and Lsc/y compared to the initial
case by about by 92%, and 92%, respectively. Moreover, it decreased the deposition parameters
dd/y and Ld/y by 97% and 94%, respectively.
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0.8
without sill
h sill / y = 0.10
h sill / y = 0.20
h sill / y = 0.30
h sill / y =0.35
h sill / y = 0.50
0.7
0.6
d sc / y
0.5
0.4
0.3
0.2
(a)
0.1
0
0.65
0.7
5
without sill
h sill / y = 0.10
h sill / y = 0.20
h sill / y = 0.30
h sill / y =0.35
h sill / y = 0.50
4
L sc / y
0.75
3
0.8Fn Culvert
0.85
0.9
0.95
1
0.9
0.95
1
0.9
0.95
1
(b)
2
1
0
0.65
0.7
1.4
0.8
0.85
Fn Culvert
without sill
h sill / y = 0.10
h sill / y = 0.20
h sill / y = 0.30
h sill / y =0.35
h sill / y = 0.50
1.2
1
dd/y
0.75
0.8
0.6
0.4
0.2
(c)
0
0.65
0.7
0.75
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0.85
fn culvert
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without sill
h sill / y = 0.10
h sill / y = 0.20
h sill / y = 0.30
h sill / y =0.35
h sill / y = 0.50
10
Ld/y
8
6
4
2
(d)
0
0.65
0.7
0.75
0.8
0.85
Fn Culvert
0.9
0.95
1
Figure. 8 Relations between Fn and the different scour parameters for different sill positions (Hsill/y) )
(a) dsc/y, (b) Lsc/y ,(c) dd/y ,(d) Ld/y
5. STATISTICAL REGRESSION
Based on the experimental data, empirical correlation to predict the different scour parameters
dsc/y and Lsc/y at the outlet of the box culvert were developed using multiple regression
techniques. Different scour parameters dsc/y and Lsc/y could be estimated from the following
equations. These equations are valid within the following ranges of the involved parameters:
Lsill/y [0.86 - 4.3], Hsill/y [0.1 - .5], Fn [0. 7 − 0.95] and yt/y [1.3-2.6].
d sc
L
H
H
y
 1.48  0.73Fn  0.03sin  0.032( sill )  4.86( sill )  6.3( sill )2  0.42( t )
y
y
y
y
y
(9)
Lsc
L
H
H
y
 4.63  3.3Fn  0.1sin   0.9( sill )  18.17( sill )  23.33( sill ) 2  1.63( t )
y
y
y
y
y
(10)
Table 2: provides the statistical measures of the above equations.
equation
9
10
Multiple R
0.944204
0.950835
R Square
0.891521
0.904088
Adjusted R Square
0.870525
0.885524
Standard Error
0.075445
0.388242
Figure 9 shows a comparison between the measured and the predicted values of Eqs. (9 and
10). Using the data sets used in this study, Figure 9 shows the calculated values of the
investigated parameters against the measured ones. Presence of a small scatter between these
variables can be noted. Generally, it can be observed that, there is an acceptable agreement
between the measured data and the predicted ones. The residuals of the statistical equations are
plotted versus the predicted values as shown in Figure 10. The residuals show random
distribution around the line of zero. These figures confirm that the developed equation is
statistically correct.
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Abdel Aal G.M., Elsaiad A.A., Elnikhely E.A. and Zaki E.M
dsc/y exprimental
1
0.8
R² = 0.8915
0.6
0.4
0.2
(a)
0
0
0.2
0.4
0.6
dsc/y predicted
0.8
1
L sc/y exprimental
5
4
3
R² = 0.9041
2
1
(b)
0
0
1
2
3
L sc/y predicted
4
5
Figure. 9 Comparison between experimental and predicted dsc/y and Lsc/y for the proposed equations
(a) equation 9 , (b) equation 10
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Minimizing of Scour Downstream the Outlets of the Box Culvert
0.4
0.3
Residual
0.2
0.1
0
-0.1
-0.2
-0.3
(a)
-0.4
0
0.2
0.4
0.6
0.8
1
dsc /y predicte
1.5
1
Residual
0.5
0
-0.5
-1
(b)
-1.5
0
1
2
3
dsc /y predicte
4
5
Figure. 10 Residuals of dsc/y and Lsc/y for the proposed equations (a) equation 9 , (b) equation 10
6. CONCLUSIONS
In the present study, a new approach was suggested and tested experimentally to minimize the
scour downstream box culvert outlet. Prediction equations were developed using the scour and
flow parameters. Within the experimental range of the present research, the analysis of the
collected experimental data and evidence revealed that:
1. The use of the rigid bed with a length of 7 times of culvert height reduced the
average values of the relative depth and length of scour by 60% compared with
previous results without rigid bed;
2. Fixing a sharp edge sill at 0.86 y from the culvert outlet reduces the scour and
deposition parameters 𝑑sc/y,𝐿sc/y,𝑑𝑑/y and 𝐿𝑑/y by 64%, 78%, 97% and 94% ,
respectively compared to the initial case;
3. The use of straight sill compacted the different scour parameters dsc/y and Lsc/y
compared to the initial case by about by 79%, and 92%, respectively.
4. The use oof sharp edge sill height of hsill/y=0.35 compacted the different scour
parameters dsc/y and Lsc/y compared to the initial case by about by 92%, and 92%,
respectively. Moreover, it decreased the deposition parameters dd/y and Ld/y by
97% and 94%, respectively.
5. The reduction of the scour parameters due to using the sharp edge sill is 60%.
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Abdel Aal G.M., Elsaiad A.A., Elnikhely E.A. and Zaki E.M
6. The developed statistical equations compare well with the experimental
measurements with a mean R2 =90 %.
ACKNOWLEDGEMENT
The authors are grateful to Faculty of Engineering, Zagazig University, Zagazig, Egypt
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