SN Provided Data

High Flood Discharge 100 yrs

Bed level of river
Water surface elevation for Q40
High flood level before weir construction

Permissible afflux
1
Pond level
Channel Depth
Free board
Height of weir

Safe exit Gradient

Average grain size (mm)

Lacey's silt factor
Coefficient of discharge for weir
B
Specific gravity of concrete
Specific gravity of boulders
Specific gravity of plum concrete
F
Weir crest level
Undersluice crest level
Width of weir portion
Width of indersluice portion
Divide wall
No. of vertical gate at undersluice
Total water way

Check for the Max

Average discharge intensity

Scour depth

Velocity of approach

Head due to velocity of approach

 U/S HFL after construction of weir
U/S TEL
Head over undersluice crest
Head over the weir crest
Discharge through undersluice
Discharge through undersluice
Total discharge

S.N Parameter

d/s TEL
1A u/s TEL
Head losss
Discharge intensity
b) High flood with 20% concentr
New discharge intensity (m3/s)
New velocity head (m)
u/s TEL (m)
d/s TEL (m)
1B Head loss(m)

2. Pond Level Con

2.a With no concentrati
S.N Parameter
Head over the crest of undersluices
Head over the crest of weir (m)
Discharge passing through undersluice for this head
Discharge passing through weir for this head
Total Discharge (m3/s)

Average discharge intensity (cumecs/meter)

Normal scoured depth

Velocity Approach

Velocity head
 u/s TEL (m)
d/s TEL (m)
Head loss (m)
A Discharge Intensity(cumecs/meter)

2.b Pond Level with 20% concen

New discharge intensity (cumecs)

New head (m)

u/s TEL (m)
d/s TEL (m)
B Head loss (m)
Symbol Value
Qhf 210.819
3183
3183.3
3187.4

1.2
3184.5
1.5
1.3
3.2
1/5
GE

Assumptions
dmm 26.1
f 1
Cd 2
Gc 2.4
Gb 2.65
Gp 2.525
Fixing the Crest level and Waterways
3186.2
3183
26
2.5
1
1
30.5

Check for the Maximum Flood Passage Over this Waterways with Afflux

q 6.912

R 4.89861951437879

va 1.41102985042354
𝑣𝑎2/2𝑔
0.101478350600728
 𝑣𝑎2/2𝑔

3188.6
3188.7014783506
5.70147835060061
3.70147835060079
Qu = 1.7(Lu-KnHu)Hu3/2 57.8588969002966
Qw = CdLwH w
3/2
314.764024709503
Q = Qu+Qw 372.6229216098

Design of Weir
Symbol/Eqaution Value
1. High Flood Condition
a) Assuming no concentration and retrogression
HFL before construction+velocity head 3187.50
HFL before construction+velocity head+afflux 3188.70
HL = u/s TEL - d/s TEL 1.20
qp = CdHu3/2 14.24
b) High flood with 20% concentration and 0.5 m retrogression
qn = 1.2 * qp 17.09
((𝑁𝑒𝑤 𝑑𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒
𝑖𝑛𝑡𝑒𝑛𝑠𝑖𝑡𝑦)/𝐶𝑑)2/3 4.18
Bed level of river + new velocity head 3187.18
d/s TEL without retrogression-retrogression depth 3187.00
HL = u/s TEL - d/s TEL 0.18

2. Pond Level Condition

2.a With no concentration and retrogression
Symbol/equation Value
Hup = pond level- crest level of undersluice 1.50
Hwp = weir crest level- pond level 1.70
Qup = 1.7(Lu-KnHup)Hup3/2 7.81
Qwp = CdLwHwp3/2 115.26
Qp=Qup+Qwp 123.07
q=(𝑄_𝑝)/(𝑇𝑜𝑡𝑎𝑙
𝑤𝑎𝑡𝑒𝑟𝑤𝑎𝑦𝑠) 4.03
R=1.35((𝑞^2)/𝑓)^1/3
2.72

V=𝑞/𝑅
1.49
(𝑉^2)/2𝑔
0.11
pond level + velocity head 3184.61
stage discharge curve for Qp + velocity head 3184.07
HL = u/s TEL - d/s TEL 0.54
q2a = CdHu3/2 4.88

2.b Pond Level with 20% concentration and 0.5m retrogression

q2b = 1.2* q2a 5.86
((𝑁𝑒𝑤 𝑑𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒
𝑖𝑛𝑡𝑒𝑛𝑠𝑖𝑡𝑦)/𝐶𝑑)^2/3 2.05
Bed level + new head 3185.05
d/s TFL(case 2a) -0.5 3183.57
1.47
 Unit
m3/s
amsl
amsl
amsl

m
amsl
m
m
m

mm

tons cu.m-2
tons cu.m-3
tons cu.m-4
erways

s Waterways with Afflux

cumecs/meter
 Units
dition
and retrogression

retrogression depth=0.5m

Remarks
From stage vs discharge curve i.e. rating curve
Reference

Taken E.G. Elev of 100yrs flood for safe

Desirable limit of afflux is 1-1.2m. More
commonly 1.0 m.
However,in steep reacehs with rocky bed, higher
afflux is permitted.
Pond level=full supply level+modular head
Pond level-bed level
Generaly, 1 to 1.5m
1.5+1.3=2.8 ̴ 3.2
0.14 to 0.17 for fine sand
0.17 to 0.20 for coarse sand
0.020 to 0.25 for shingle

random, need to research

broad Crested weir

Bed level+height of weir

Bed level of river
As per available site condition
As per available site condition

q=𝑄ℎ𝑓/(𝑇𝑜𝑡𝑎𝑙
𝑤𝑎𝑡𝑒𝑟𝑤𝑎𝑦𝑠)
R=1.35(𝑞2/𝑓)1/3

V=𝑞/𝑅

𝑉2/2𝑔
 𝑉2/2𝑔

u/s HFL+afflux+velocity head

u/s HFL+afflux

K=0.1, n=0
Cd=1.7 for broad crested weir
Q > Qhf ; Hence safe.

Reference
S.NO. Parameters

1 Discharge intensity
2 U/S TEL
3 D/S TEL
4 Head loss, 𝐻𝑙
5 E_f2(from plate no. 10.1) (in m)
6 Level at which jump will form (in m)
7 𝐸𝑓1 = 𝐸𝑓2 + 𝐻𝑙 (in m)
8 y1 (Plate No. 10.2) (in m)
9 y2(Plate No. 10.2) (in m)
10 Length of concrete floor (in m)
11 Froude No , 𝐹𝑟1 (in m)

Length of d/s floor

RL of d/s floor

Calculation of floor length for

Parameters
S.N Depth of Sheet Pile Lines fr
Total discharge passing through undersluices
Overall waterways of undersluices (m)
Average discharge intensity (q)

Depth of Scour ®
Bottom RL of d/s cutoff
Depth of d/s cutoff (m)
RL of u/s cutoff
RL of u/s floor
Depth of u/s cutoff
New RL of u/s cutoff
Glacis gradient
Horizontal length of glacis (m)
A Maximum static head (m)
Safe exit gradient (GE)
 λ

α λ =1+(√1+𝛼^2)/2

Total Floor length (m)

u/s floor length (m)
 RESULT
Design of weir section
High flood level
Without concentration and retrogression With concentration and
retrogression

14.24 17.09
3188.7 3187.18
3187.5 3187
1.19999999999982 0.179999999999836
4.7 4.6
3182.8 3182.4
5.89999999999982 4.77999999999984
2.1 3
4.2 3.2
10.5 1
1.48113286758327 1.04105374992512

15.75 taking FOS as 1.5

3182

Calculation of floor length for Khosla's safe exit gradient

Symbol/Eqaution Value
Depth of Sheet Pile Lines from Scour Consideration
57.85
3.5
16.53
R=1.35((𝑞^2)/𝑓)^1/3
8.76
d/s flood level - 1.5R 3174.3
dcutoff = RL of d/s floor - RL of d/s cutoff 7.7
u/s flood level-1.25R 3176.45
bed level 3183.00
ucutoff = bed level - RL of u/s cutoff 6.55
3176.00
1 in 3
Gradient*depth of u/s floor 9.60
H = Pond level-d/s floor level 2.50
0.2
 Ge=𝐻/
(3.14∗𝑑_𝑐𝑢𝑡𝑜𝑓𝑓∗√"λ" )
0.21
λ =1+(√1+𝛼^2)/2
5
α*dcutoff 40.00
Total floor length-horizontal glacis length-length of d/s floor 30.40

63.7
 Pond level flow Units
Without concentration and retrogression With
concentration
and
retrogression

4.88 5.86
3184.61 3185.05
3184.07 3183.57
0.539999999999964 1.48
2.3 2.7
3181.77 3180.87
2.83999999999996 4.18
1.1 1
2.1 2.5
5 7.5
1.33888651196945 1.854857661438

Take 15m

Remarks

Calculated earlier

d/s cutoff at depth 1.5R ( Actual RL taken= 3174)

Take 8m
u/s cutoff at depth of 1.25R

take 7m as u/s cutoff depth

V:H (Assume)

Take 1/5
From Plate 11.2 Garg Book
Considering 1.5 as safety factor taken 60m
Remarks

Plate 10.1 (q vs Ef1)of Blench curve

SN Parameter

Total floor length(m)

Depth of u/s pile(m)
Depth of d/s pile(m)
Distance between two piles

u/s floor thickness(m)

d/s floor thickness(m)
u/s pile line
α
λ
ф_E
ф_E(%)
ф_E1(%)
ф_C1(%)
ф_D
ф_D(%)
ф_D1(%)
d/s pile line
α
λ
ф_C2(%)
ф_E2(%)
ф_D2(%)
Correction to ф_C1(%)
a) Mutual interference
Depth of d/s pile bottom level below point C1(m)
Total floor length(m)
Distance between two piles(m)
Depth of pile on which effect is considered(m)
Correction(%)
b) Floor thickness
Correction(%)
ф_C1(%)
Correction to ф_E2(%)
a) Mutual interference
Depth of u/s pile bottom level below point C2(m)
Total floor length(m)
Distance between two piles(m)
Depth of pile on which effect is considered(m)
Correction(%)
b) Floor thickness
Correction(%)
ф_E2(%)
Symbol/Equation Value
Uplift pressure
Given
b 45.00
d1 7.00
d2 8.0
43.50
Assumption
1
1.5

b/d1 6.429
λ=(1+SQRT(1+α^2)/2 3.753
ф_E=1/π*arccosine((λ-2)/2) 0.345
34.548
100.000
100-ф_E(%) 65.452
ф_D=1/π*arccosine((λ-1)/2) 0.238
23.799
100-ф_D(%) 76.201

b/d2 5.625
λ=(1+SQRT(1+α^2)/2 3.357
0.000
ф_E2(%)=ф_E(%) 34.548
ф_D2(%)=ф_D(%) 23.799

D 8.040
b 45.000
b' 43.50
d1 7.000
Correction=19(d+D)/b*SQRT(D/b') 2.730

Thickness*(ф_D1(%)-ф_C1(%))/(River bed level-bottom level of u/s cutoff) 1.569

69.751

D 4.500
b 45.000
b' 43.500
d2 8.000
Correction=19(d+D)/b*SQRT(D/b') 1.698
Thickness*(ф_E2(%)-ф_D2(%))/(d/s floor level-bottom level of d/s cutoff) 1.389
31.46
Remarks

Slightly greater than Floor area of weir( As taken 60m)

Slightly greater than u/s floor depth
Slightly greater than d/s floor depth
(60-0.75*2=58.5m) Piles are offsetted 0.75m inside from floor ends

Positive correction

Positive correction
Corrected

Negative correction
Negative correction
Corrected
 Elevat
u/s water d/s water u/s pile
Condition of flow Head(m)
level (m) level (m) ф_E1(%)
100
2.500
3184.50 3182 2.50
No flow, maximum static head 3184.500
1.700
3188.70 3187.00 1.70
High flood with concentration and retrogression 3188.701
1.040
Pond level with concentration and retrogression
3184.50 3183.5 1.0 3184.500
 Elevation of subsoil HGL
u/s pile d/s pile
ф_D1(%) ф_C1(%) ф_E2(%) ф_D2(%) ф_C2(%)
76.201 65.452 34.548 23.799 0
1.905 1.636 0.864 0.595 0.000
3183.905 3183.636 3182.864 3182.595 3182.000
1.295 1.113 0.587 0.405 0.000
3188.297 3188.114 3187.589 3187.406 3187.001
0.792 0.681 0.359 0.248 0
3184.252 3184.141 3183.819 3183.708 3183.460
 Pre-Jump Profile Calculation
High level flood with concentration and
Distance from the start of retrogression (q=17.09 cumecs/m)
glacias Glacis level in meter
Ef1=u/s TEL-Glacies level
0 3186.2 0.98
3 3185.2 1.98
6 3184.2 2.98
9 3183.2 3.98
11.4 3182.4 4.78
12 3182.2 4.98
15.00 3181.2 5.98
16 3180.2 6.98

Post-Jump Profile Calculation

High level flow
X/Y1 on plate 10.3(a) F2=1.08 , Y1=3
Y/Y1 Y X=col. 1 * 1.08
1 1.5 1.62 1.08
2.5 2 2.16 2.7
5 2.2 2.376 5.4
7.5 2.5 2.7 8.1
10 2.6 2.808 10.8
12.5 2.7 2.916 13.5

Maxiumum unbalnaced head in the jump

RL of HGL
Start of u/s floor 0 3188.29690173666
HFL Point of Jump 41.80
End of d/s Floor 45 3187.58879337627
Start of u/s floor 0
Pond Level Point of Jump 46.4
End of d/s Floor 45

Taking 4.6m as maximum unbalance head

flood with concentration and
ssion (q=17.09 cumecs/m)
y1 from plate 10.2
-
-
-
-
2.200
1.800
1.600
1.200

Unbalanced Head

4.59999999999991

1.48
SN Parameter Symbol/Equation
Design of Stillin
y2(m)
Froude No. F_r=q/SQRT(gy1^3)
L_b/y2
Length of stilling basin(m) L_b(m)
Design of end sill (Preferably denated)
Height(m) 0.2*y2
Length(m) 2*height
Width(m) 0.15*y2
Spacing(m) 0.15*y2
Top crest(m) 0.02*y2
No. of block Crest length = (n-1)*spacing+n*width 30.5=(n-1)*0.7+n*0.7
 Value
Design of Stilling Basin
4.2
1.48
3
12.6

0.84
1.68
0.63
0.7
0.0296
48
 Remarks

Highest from previous table

F_r <4.5, Stilling Basin I is provided as per IS 4997:1968
From graph

Take 1.5 m
Take 2m
Take 0.7m
Clear spacing
Take 0.03m
 Maxiumum unbalanced head= 4.6 m
Thickness of Glacis Floor
Distance Unblanced Heads Thickness Actual Thickness
Point of Jump 4.8 3.9 4
5m beyond toe 4.6 3.71 4
10m beyond toe 2.3 1.85 2
15m beyond toe 1.8000 1.45 2

d/s protection works

Thickness of launching apron t=2.25D/L 2
Normal Scour Depth(m) R 9
D(m) 2R-y 13 y=d/s concentrated HFL-d/s floor leve
Length of launching apron L=1.2D 15
Size of c.c. block At 10cm clear gap filled with Bajri, for 1.5D
Length(m) 1.2
Breadth(m) 1.2
Thickness(m) 1 1m filter at base added
c.c. block floor length(m) 1.2D 15.02 Take 16 m
Number of rows 14

u/s protection works

Thickness of launching apron t 2
Anticipated Scour Depth(m) 1.5R 13
D(m) 1.5R-y 15 y=d/s concentrated HFL-d/s floor leve
Length of launching apron L=1.25D/t 9 16
Size of c.c. block At 10cm clear gap filled with Bajri, for 1.5D
Length(m) 1.2
Breadth(m) 1.2
Thickness(m) 1 1m filter at base added
c.c. block floor length(m) 1.2D 17
Number of rows 10
 Remarks

Thickness=(𝑈𝑛𝑏𝑙𝑎𝑛𝑐𝑒𝑑 𝑆𝑡𝑎𝑡𝑖𝑐
𝐻𝑒𝑎𝑑)/(𝐺−1)

y=d/s concentrated HFL-d/s floor level

10cm clear gap filled with Bajri, for 1.5D m run

1m filter at base added

Take 16 m

y=d/s concentrated HFL-d/s floor level

16
10cm clear gap filled with Bajri, for 1.5D m run

1m filter at base added