CantileverRetaining 6m Walls

7/28/2019 CantileverRetaining 6m Walls

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Dikchu Hydroelectric Project

Haridwar Infrastructure Private Limited

Report on Cantilever Retaining Wall

Doc.No:0917-DES-PH-005-R0

Annexure-1

Height of retaining wall H = 8.25 m H

Surcharge angle β = 0 degAngle of repose ф = 37 deg

Unit weight of concrete = 25 kN/m3

Unit weight of Backfill material = 14 kN/m3

Bearing capacity of soil SBC = 200 kN/m2

Co-efficient of internal friction = 0.50

Partial factor of safety FOS = 1.5

Grade of concrete fck = 25 N/mm2

Yield stress of steel fy = 500 N/mm2

Cover provided C = 0.04 m

Dimensioning of retaining wall: =

Height of stem h = 7.87 m

Height of retaining wall H = 8.25 mThickness of stem at Top = 0.25 m

Thickness of stem at Bottom = 0.62 m X2

Toe width b1 = 0.96 m X3

Base width B = 3.30 m L

Heel width b2 = 1.72 m

Base slab thickness = 0.38 m X1

Active earth pressure co-efficient Ka = 0.249

Height of backfill at the end of base slab = 7.870 m

H1 = 8.250 m

Active Earth PressureP

e = 118.43 kNHorziontal Component Ph = 118.43 kN

Vertical component Pv = 0.00 kN

Weight of earth fill W3 = 189.51 kN

0.25 0

0.96 0.62 1.72

A

Design of Cantilever Retaining Wall

7.87

0.38

3.30

Height of backfill at the end of base

slab+base slab

7 .

8 7 0

1| Page







Annexure-1

Vertical Horizontal

Weight of stem 49.19 1.455 71.57

36.40 1.21 43.92

2 W2 Weight of Base slab 31.35 1.65 51.73

3 W3 Weight of Earth fill 189.51 2.44 462.40

4 Pv Earth Pressure 118.43 2.75 325.70

5 Ph Earth Pressure 0.00 3.30 0.00

Total 306.45 118.43 629.62 325.70

Total vertical Load 306.45 kN

Total Horizontal Load 118.43 kN

Factors of safety:

Against oveturning:FOS = 1.93 Safe

Against sliding:

FOS = 1.29 Unsafe, Shear Key Required

Eccentricity calculation:

z = 0.99

e = 0.658 m

Pressure Distribution

At Toe Pmax = 204.00 kN/m2

At Heel Pmin = -18.27 kN/m2

A B

Design of Stem:

Height of stem = 7.87 m

Dia of main bar = 20 mm

Dia of distribution bar = 12 mm

Moment at the base M = 282.73 kNm

Factored Moment Mu = 424.10 kNm

Thickness required d = 0.351 m

Thickness Provided at bottom dpro = 0.558 mThickness Provided at top = 0.188 m

Avg thickness = 0.373 m

Area of steel required Ast 1873 mm2/m A

Min reinforcement 669.6 mm2/m

Spacing provided 150.00 mm

Reinforcement provided 2094.40 mm2/m

Percentage of reinforcement provided pt 0.38 %

Overturning

moment (kNm)

Distance

from point

A (m)

Magnitude (kN) Resisting

moment

(kNm)

Description

1 3 9 . 3

4

9 7 . 5 8

2 0 4 . 0

0

S.No Load

1 W1

- 1 8 .

2 7

3.30D

f

c

2| Page







Annexure-1

Design of toe slab:

Vertical Horizontal +ve -ve

1 W1 Weight of toe slab 9.12 0.48 4.38

2 W2 Upward Pressure 164.80 0.51 84.07

Total 173.92 4.38 84.07

Total vertical force 155.68 kN

Net working moment M = 79.69 kNm

Factored moment Mu = 119.54 kNm

Depth required dreqd = 0.19 m

Dia of the main bar = 12 mm

Dia of the distribution bar = 12 mm

Depth provided d prov = 0.32 m

Reinforcement reqd Ast = 904.00 mm2/m C

Min reinf 386.40 mm2/m

Spacing reqd 125.00 mm


Percentage of steel provided 0.28 %

Minimum reinforcement:



Provide 12dia at 125c/c - main bar


Design of shear Key:

Co-efficient of passive pressure Kp 4.02 3750

Upward pressure near the key P 139.34 kN/m2

1875

Let depth of shear key a 0.40 m 1725

Width of the shear key 0.30 m

Passive pressure developed Kp*P 560.52 kN/m2

Total passive pressure Pp *a 224.21 kN

Weight of earthfill in the key Wa 18.48 kN

Self weight of the key W 306.45 kN

FOS against sliding 3.26

Moment about C

S.No Load Description

Magnitude (kN) Distance

from point

C

4| Page







Annexure-1

Height of retaining wall H = 3.5 m

Surcharge angle β = 0 degAngle of repose ф = 20 deg

Unit weight of concrete = 25 kN/m3

Unit weight of Backfill material = 14 kN/m3

Bearing capacity of soil SBC = 400 kN/m2

Co-efficient of internal friction = 0.50

Partial factor of safety FOS = 1.5

Grade of concrete fck = 25 N/mm2

Yield stress of steel fy = 500 N/mm2

Cover provided C = 0.04 m

Dimensioning of retaining wall: =

Height of stem h = 3.10 m

Height of retaining wall H = 3.50 mThickness of stem at Top = 0.15 m

Thickness of stem at Bottom = 0.3 m

Toe width b1 = 0.40 m

Base width B = 1.80 m

Heel width b2 = 1.10 m

Base slab thickness = 0.40 m

Active earth pressure co-efficient Ka = 0.490

Height of backfill at the end of base slab = 3.100 m

H1 = 3.500 m

Active Earth PressureP

e = 42.04 kNHorziontal Component Ph = 42.04 kN

Vertical component Pv = 0.00 kN

Weight of earth fill W3 = 47.74 kN

0.15 0

0.40 0.3 1.10

A

Design of Cantilever Retaining Wall

Height of backfill at the end of base

slab+base slab

3 .

1 0 0

3.10

0.40

1.80

5| Page







Annexure-1

Vertical Horizontal

Weight of stem 11.63 0.625 7.27

5.81 0.50 2.91

2 W2 Weight of Base slab 18.00 0.90 16.20

3 W3 Weight of Earth fill 47.74 1.25 59.68

4 Pv Earth Pressure 42.04 1.17 49.05

5 Ph Earth Pressure 0.00 1.80 0.00

Total 83.18 42.04 86.05 49.05

Total vertical Load 83.18 kN

Total Horizontal Load 42.04 kN

Factors of safety:

Against oveturning:FOS = 1.75 Safe

Against sliding:

FOS = 0.99 Unsafe, Shear Key Required

Eccentricity calculation:

z = 0.44

e = 0.455 m

Pressure Distribution

At Toe Pmax = 116.33 kN/m2

At Heel Pmin = -23.91 kN/m2

A B

Design of Stem:

Height of stem = 3.10 m

Dia of main bar = 20 mm

Dia of distribution bar = 12 mm

Moment at the base M = 34.08 kNm

Factored Moment Mu = 51.12 kNm

Thickness required d = 0.122 m

Thickness Provided at bottom dpro = 0.238 mThickness Provided at top = 0.088 m

Avg thickness = 0.163 m

Area of steel required Ast 516 mm2/m

Min reinforcement 285.6 mm2/m



Percentage of reinforcement provided pt 0.22 %

Resisting

moment

(kNm)

Overturning

moment (kNm)

1 1 6 . 3

3

8 5 .

1 6

6 1 . 7 9

- 2 3 .

9 1


from point

A (m)


1.80

1 W1

D

f

c

6| Page







Annexure-1

Distribution reinf:

Area of steel required 195.60




Check for shear:

Shear force developed 42.04 kN

Shear stress developed 0.26 N/mm2

Permissible shear stress 0.35 N/mm2

Safe

Design of heel slab:

Description


1 W2 Weight of heel slab 11.00 0.55 6.05

2 W3 Weight of earth fill 0.00 0.00 0.003 W4 42.04 1.03 43.44


Total 73.88 49.49 20.10

Net downward force 53.04 kN

Netupward force 20.84 kN

Net force 32.21 kN






Depth provided dprov = 0.34 m

Reinforcement reqd Ast = 302.00 mm2/m




Percentage of steel 0.12 %

Check for Shear:

Shear force developed 32.21 kN

Shear stress developed 0.09 N/mm2

0.36 N/mm2

Safe



Spacing reqd 550 mm



S.No Load


from point

B (m)

Moment about B

7| Page







Annexure-1

Design of toe slab:


1 W1 Weight of toe slab 4.00 0.2 0.80


Total 44.30 0.80 8.48

Total vertical force 36.30 kN






Depth provided d prov = 0.34 m

Reinforcement reqd Ast = 78.00 mm2/m




Percentage of steel provided 0.12 %






Design of shear Key:

Co-efficient of passive pressure Kp 2.04 3750

Upward pressure near the key P 85.16 kN/m2

1875

Let depth of shear key a 0.40 m 1725

Width of the shear key 0.30 m

Passive pressure developed Kp*P 173.70 kN/m2

Total passive pressure Pp *a 69.48 kN

Weight of earthfill in the key Wa 10.08 kN

Self weight of the key W 83.18 kN

FOS against sliding 2.76



from point

C

Moment about C

8| Page



1000

3500

6000



1

3.5

0.91

4

3.64 943800

0.961538 141570

235950

188760

CantileverRetaining 6m Walls

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