DN400

Calculations for Isolation Valve Chamber for DN400 @ CH 0+003

1

Design Parameters 1.1

for

IVC-DN400

Soil Condition From Geotechnical report Reference Bore Hole

Net Allowable Bearing Pressure

near BH-6

=

160

kN/m2

@ Depth =

2

m

Soil Parameters used in Design For layer designation Angle of Internal Friction for Soil Pressure Calculations = 30 ° 0.524 radians Active Coefficient Ka = (1-Sinf/1+Sinf) Ka = Passive Coefficient Kp = (1+Sinf/1-Sinf)

0.33

Kp =

3.00

K0 =

0.50

Soil Pressure at Rest Coeff.

Angle of Internal Friction for Friction Calculations = 30 ° = 0.524 radians  = Tan (2/3.) Friction Factor Concrete/Soil 0.36  = Tan  Friction Factor Soil/Soil = 0.58 Net Allowable Bearing Pressure

1.2

=

160 kN/m2

Soil Bulk Density

=

17.0 kN/m3

Submerged Soil Density

' =

7.0 kN/m3

Density of Water

w =

10.0 kN/m3

Concrete Density

c =

24.0 kN/m3

Submerged Concrete Density

c' =

14.0 kN/m3

Unit Weights

1.3

Materials

(1)

Concrete Specified Characteristic Strengt Elastic Modulus

(2)

fc =

30 N/mm2

Es =

28,000 N/mm2

Reinforcement (BS 4449 Gr 460) ( See Table 1.1) Specified Yield Strength Elastic Modulus Minimum cover to reinforcement: Cover Slab Wall and Foundation

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fy =

460 N/mm2

Es =

200,000 N/mm2

50 mm 75 mm 1 of 32

1.4

Factors of Safety Stability of Structure Required Factor of Safety Against Sliding = Required Factor of Safety Against Overturning = Required Factor of Safety Against Flotation = Required Factor of Safety Against Rotation = Factor of Safety Against Allowable Bearing Capacity

1.5

1.4 1.5 1.2 1.5 1.0

Load Combination Uu = 1.4[D.L.]+1.4[S.P]+1.6[I.L]+1.4[T.F] Ultimate Limit State i.e. Partial Load Factor for Dead Load = 1.4 Partial Load Factor for Soil Pressure = 1.4 Partial Load Factor for Imposed Load = 1.6 Partial Load Factor for Pipeline Thrust = 1.6 Us = 1.0[D.L.]+1.0[S.P]+1.0[I.L]+1.0[T.F] Serviceability Limit State i.e. Partial Load Factor for Dead Load = 1.0 Partial Load Factor for Soil Pressure = 1.0 Partial Load Factor for Imposed Load = 1.0 Partial Load Factor for Pipeline Thrust = 1.0

2.

Pipe Details Maximum Pressure for design Pressure in SI units Int. Dia Ext Dia Inner Area Externa Area In Line Force TF Weight of Pipe No. of valves closed

3.

P=

=

16.0 1,600 0.400 0.429 0.126 0.145 201 0.89 1

bar kN/m2 m m m2 m2 kN kN/m

Chamber Dimensions and Levels Base Length Base Width

4.12 m 4.81 m

Chamber width -inner dimension

D= B= b1 =

Chamber length -inner dimension

d1 =

2.59 m

Side wall thickness

tSW =

0.30 m

2.41 m

Pipe Invert Level Ground Level Finished Ground Level Water Table Level Type of Construction

IL = GL = FGL = WL = TC

14.17 18.30 18.30 0.00 III

Top of Base Slab Level Top of Chamber Wall Level

TBL = TWL =

13.87 m 18.60 m

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m m m m

DRY

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B 1.20

2.41

1.20

0.78 Back Wall 0.3 1.01

0.80

0.3

0.30 2.41

m

0.5

A

A 1.94

2.59 m

1.217

2.59

4.12 0.55 0.35 Front Wall Cover Slab line

`

0.75

Rotating Point

B PLAN 0.3

0.3 0.3

4.43 0.5145 0.60 0.60 4.81 SECTION A-A

WTL 4.43 5.63 m

Flow

0.5145 0.30

0.60 0.60 0.50

3.1 4.1 SECTION B-B

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0.50 Overturning Point

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4.

Stability Check 4.1

Bearing Capacity Check Factor of Safety Required a) Calculation of Pipe Thrust

1.0

Pressure in bar Pressure in SI units Int. Dia Ext Dia Inner Area Externa Area In Line Force TF No. of valves closed

16.0 1,600 0.400 0.429 0.126 0.145 201 1

bar kN/m2 m m m2 m2 kN

b) Volumes and Weights Concrete Density

c =

24.0 kN/m3

Submerged Concrete Density

c' =

14.0 kN/m3

Concrete Shear Key (front) Shear Key (back) Foundation Slab Front Wall (minus pipe hole) Back Wall (minus pipe hole) Side Walls1 Side Walls2 Precast Cover Slab

Volume m3 1.44 1.44 11.87 3.93 3.37 2.76 2.76 1.25 28.82

Weight kN 34.60 34.60 284.92 94.38 80.90 66.14 66.14 29.93 691.62

Soil, Water & Pipe Soil Bulk Density

=

17.0 kN/m3

Submerged Soil

' =

7.0 kN/m3

Density of Water Weight of Pipe

w =

10.0 kN/m3 0.89 kN/m

=

Volume

Weight kN 269.61 278.60 234.24 234.24

m 15.86 16.39 13.78 13.78 3

Soil from FGL to TBL - front (minus pipe) Soil from FGL to TBL - back (minus pipe) Soil from FGL to TBL - side1 Soil from FGL to TBL - side2 Pipe including Water

8.8 length of pipe is taken for the entire chamber base 1026

c) Bouyant Force No bouyant force since no water level is encountered. d) Calculate Average Bearing Pressure Total Weight of Concrete and Soil Bouyant force (uplift force) Total Bearing Area Average Bearing Pressure

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1717.15 0.00 19.79 86.78

kN kN m2 kN/m2

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e) Soil pressure calculations for the bearing capacity check : (Water table above TBL) Active Soil Pressure (for Bearing Capacity and Overturning check) = Angle of internal friction 30 ° Active pressure coefficient Ka = 0.33 = Soil Bulk Density 17.0 kN/m3 Submerged Soil Density

' =

Width of chamber wall

b1 =

2.41 m

Width of foundation slab

b2 =

4.81 m

7.0 kN/m3

Total Active soil pressure a1 a2

(at wall) (at foundation slab)

Force 133.78 kN 164.38 kN

= =

FGL

Active Soil Pressure 0.00 kN/m2 d1 = 4.43 m a1

TBL

p1 =

p1 a2

ka.d1. =

25.10 kN/m2

P21

p2 = ka.(d1+d2). =

31.90 kN/m2

P22

d2 = 1.20 m

p2

Passive Soil Pressure (for Bearing Capacity and Overturning check) = Angle of internal friction 30 ° Passive pressure coefficient Kp = 3.00 = Soil Bulk Density 17.0 kN/m3 Submerged Soil Density

' =

Width of chamber wall

b1 =

2.41 m

Width of foundation slab

b2 =

4.81 m

7.0 kN/m3

Total Passive soil pressure assumed at foundation base slab level only for conservative design. Passive pressure at TBL = kp.d1. = = 225.93 kN/m2 Passive pressure bottom shear key

= kp.(d1+d2). =

=

Total Passive force from TBL to bottom shear key

=

287.13 kN/m2 -1479.46 kN

Moments about Centre of Base Force Force (service) (ultimate) kN Clockwise Positive - Pipe Thrust - Active soil pressure (Above TBL) - Active soil pressure (Below TBL) - Passive soil pressure below TBL

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201.06 a1 = 133.78 a2 = 164.38 p1 = -1479.46

Lever Arm m 1.71 2.08 0.60 0.60

Moment (service) kN.m

Moment (ultimate) kN.m

344.72 551.55 277.82 388.95 98.63 138.08 -887.68 -1242.75

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-

Shear Key (front) Shear Key (back) Foundation Slab Front Wall Back Wall Side Walls1 Side Walls2 Precast Cover Slab

= = = = = = = =

34.60 34.60 284.92 94.38 80.90 66.14 66.14 29.93

48.44 48.44 398.89 132.13 113.26 92.59 92.59 41.91

-1.81 1.81 0.00 -1.15 1.12 0.00 0.00 0.00

-62.58 62.58 0.00 -108.16 90.69 0.00 0.00 0.00

-87.61 87.61 0.00 -151.42 126.96 0.00 0.00 0.00

-

Soil from FGL to TBL - front Soil from FGL to TBL - back Soil from FGL to TBL - side1 Soil from FGL to TBL - side2

= = = =

269.61 278.60 234.24 234.24

377.46 390.04 327.94 327.94

-1.68 1.67 0.00 0.00

-453.89 465.54 0.00 0.00

-635.45 651.75 0.00 0.00

-

Pipe including Water

=

9

12.37

0.00

0

0.00

-

Boyant force

=

0.00

0.00

0.00

0

0.00

-172

-172

1,717

2,404

Total Moment Total Vertical Load Moment M Vertical load N Base Length Base Width Base Area Average load on base = N/BD Effective eccentricity e = M/N Middle third of the base = D/6 Variation due to moment = 6M/BD2

Allowable bearing pressure

= = D= B= = = = =

-172 1,717 4.12 4.81 19.79 87 -0.10 0.69

=

kN.m kN m m m2 kN/m2 m m

-13 kN/m2

P1 =

99.5 kN/m2

P2 = a=

74 kN/m2 4.12 m

=

160 kN/m2

Factor of safety against soil bearing pressure = 2.16 OK 4.2

Resistance to Overturning Factor of Safety Required

1.5 Force kN

Dist from Toe m

Moment kN.m

Overturning Moments Mo Pipe Thrust Active soil pressure Active soil pressure Boyant force

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(Above TBL) (Below TBL)

= a1 = a2 = =

201 133.78 164.38 0.00

1.71 2.08 0.60 0.00

345 278 99 0

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Total Overturning Moments Mo

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721

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Stabilising Moments: Shear Key (front) Shear Key (back) Foundation Slab Front Wall Back Wall Side Walls1 Side Walls2 Precast Cover Slab (ignored) Soil from FGL to TBL - front Soil from FGL to TBL - back Soil from FGL to TBL - side1 Soil from FGL to TBL - side2

= = = = = = = =

34.60 34.60 284.92 94.38 80.90 66.14 66.14 0.00

3.87 0.25 2.06 3.19 0.93 2.05 2.05 2.05

134 9 587 301 75 135 135 0

= = = =

269.61 278.60 234.24 234.24

3.74 0.39 2.07 2.07

1,009 108 485 485

9

2.06

18

0 1,479

0.00 0.60

0 888

Pipe including Water Passive soil pressure above TBL Passive soil pressure below TBL

Total Stabilising Moments Ms

4,369 Ms/Mo

Factor of Safety Against Overturning = = 4.3

6.06 OK

Resistance to Sliding Factor of Safety Required Horizontal Forces: Pipe Thrust Active soil pressure (Above TBL) Active soil pressure (Below TBL) Total horizontal sliding force Vertical Forces: Concrete weight Soil weight Pipe with water Bouyant force (uplift) Total vertical force Frictional resistance soil

1.4

= a1 = a2 = H=

201 133.78 164.38 499.23

kN kN kN kN

= 691.62 kN = 1,016.70 kN = 8.838 kN = 0.00 kN V = 1,717.15 kN to soil,

=

0.58

.V Frictional resistance from vertical force = = 991.40 kN = 1,479.46 Passive soil pressure (Below TBL) Total resisting force Factor of safety against Sliding 1.5.df

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Fr= 2,470.86 = =

Fr / H 4.95

OK

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4.5 Resistance to Rotation Factor of Safety Required

1.5

Forces acting on the chamber

Pa2 Pa1

Pa1 = a1+a2+a3 Pa2 = a4+a5 Pp1 = 0 (neglected) Pp2 = pass pressure below TBL

Pa2

T

Pa1

Pp1

Pp2

Pp1 Pp2

Rotating Point

In addition to the forces shown there is friction on the base

Rotation Moment Pipe Thrust

=

201

2.51

503.86

Active pressure at front wall: Active soil pressure (Above TBL) Active soil pressure (Below TBL)

a1 = a2 =

133.78 164.38

2.40 2.40

321.48 395.02

Activer pressure at side wall: Active soil pressure (Above TBL) Active soil pressure (Below TBL)

a1 = a2 =

133.78 164.38

2.06 2.06

275.39 338.39

Rotation Moment sum

=

1,834 kN-m

Resisiting Moment Total vertical loads (including bouyancy) Frictional resistance soil to soil, Frictional resistance at base Moment arm Frictional resistance against Rotation Passive soil pressure below TBL (backwall) = Passive soil pressure below TBL (sidewall)

=

V= = .V= = =

1,717.15 0.58 991.40 kN 3.16 m

1,479 1,479

2.40 2.06

Resistance Moment sum Factor of Safety Against Rotation

5.

3,136.93 kN.m 3,555.14 3,045.47 9,737.54

=

5.31 OK

Summary of Results Given below is the summary of the Stability Checks for the Chamber. The required values of safety are compared with the ones obtained from the calculation.

Pmax Pmin Bearing Overturning Sliding Rotation

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Required Calculated 99 74 1 2.16 1.5 6.06 1.4 4.95 1.5 5.31

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6.

Design Ultimate Loads on foundation and shear key: Chamber wall edges Toe

Heel

5.03 m 5.63 m

4.12

3.35

Ultimate Moment M Ultimate Vertical load N Base Length Base Width Base Area Average load on base = N/BD Effective eccentricity e = M/N Middle third of the base = D/6 Variation due to moment = 6M/BD2

0.76

= = D= B= = = = = =

-172 2,404 4.12 4.81 19.79 121.50 -0.07 0.69 -12.69

0.00

kN.m kN m m m2 kN/m2 m m kN/m2

Design Ultimate Soil Bearing Pressure: P1 = 134 kN/m2