268
P. Sreeja and S. Singh
0
2
4
6
8
10
12
1 2 3 4 5 6 7 8 9 10 11 12
Scour Depth (m)
Pier Number
(a)
Square
Round
Circular
Group of cylinders
Sharp Nose
0
5
10
15
20
25
1 2 3 4 5 6 7 8 9 10 11 12
Scour Depth (m)
Pier Number
(b)
Square
Round
Circular
Group of cylinders
Sharp Nose
Fig. 7 Total scour depth around parallel bridge using the 50 years return flow with a CSU equation
and b Froehlich equation
0
10
20
30
40
50
60
0
5
10
15
Scour Depth (m)
Pier Number
(a)
Jain Eq
Laursen and Toch
Lacey Eq
0
10
20
30
40
50
60
70
0
5
1 0
1 5
Scour Depth (m)
Pier Number
(b)
Jain Eq
Laursen and Toch
Lacey Eq
Fig. 8 Total scour depth around the parallel bridge using the a observed flow and b 50 years return
period flow
Hence, it is seen that there is a variation of scour depth at different location of the
piers for various kind of data’s that is for existing data and 50 years return period
using different empirical equations. It is also seen that the scour depth does not follow
the same pattern for all the piers at different flow conditions that is for existing data
and 50 years return period. This is due to the fact that the contraction scour has also
been added with the local scour which is different for different types of piers.
4 Conclusion
In the present study, the empirical equation for scour depth determination has been
critically evaluated; the determination of scour depth has also been done for different
types of piers with different bed sediments with different pier shapes,; the change in
scouring and flow characteristics in a river due to presence of multiple bridges has
P. Sreeja and S. Singh
0
2
4
6
8
10
12
1 2 3 4 5 6 7 8 9 10 11 12
Scour Depth (m)
Pier Number
(a)
Square
Round
Circular
Group of cylinders
Sharp Nose
0
5
10
15
20
25
1 2 3 4 5 6 7 8 9 10 11 12
Scour Depth (m)
Pier Number
(b)
Square
Round
Circular
Group of cylinders
Sharp Nose
Fig. 7 Total scour depth around parallel bridge using the 50 years return flow with a CSU equation
and b Froehlich equation
0
10
20
30
40
50
60
0
5
10
15
Scour Depth (m)
Pier Number
(a)
Jain Eq
Laursen and Toch
Lacey Eq
0
10
20
30
40
50
60
70
0
5
1 0
1 5
Scour Depth (m)
Pier Number
(b)
Jain Eq
Laursen and Toch
Lacey Eq
Fig. 8 Total scour depth around the parallel bridge using the a observed flow and b 50 years return
period flow
Hence, it is seen that there is a variation of scour depth at different location of the
piers for various kind of data’s that is for existing data and 50 years return period
using different empirical equations. It is also seen that the scour depth does not follow
the same pattern for all the piers at different flow conditions that is for existing data
and 50 years return period. This is due to the fact that the contraction scour has also
been added with the local scour which is different for different types of piers.
4 Conclusion
In the present study, the empirical equation for scour depth determination has been
critically evaluated; the determination of scour depth has also been done for different
types of piers with different bed sediments with different pier shapes,; the change in
scouring and flow characteristics in a river due to presence of multiple bridges has