SIZING CALCULATIONS OF THRUST BLOCKS

Project Name: Project Number:Calc. By: Date: Chck'd By: Date: Sheet No. Revision

KEO International Consultants

1.0 Design DataAllowable soil bearing capacity 182 KpaCoefficient of soil friction φ = 30 °

Friction Factor Soil/Concrete μ = 0.364

Active earth pressure coefficient 0.33

Passive earth pressure coefficient 3

Soil Bulk Density γ = 18

Submerged Soil Density γ' = 8

Concrete Density 24

Submerged Concrete Density 14Density of water 10C.L. of pipe from Ground = 0.7 mDiameter of the pipe D = 0.62 m

Test presuure p = 390Angle of bend θ = 45 °Ground Water Table Level below Ground = 1 mDepth of unblanned excavation = 0.5 mUnbalanced Thrust Force at Bent T = 90.12 kN

2.0 Factor of SafetyFactor of Safety Against Sliding = 4Factor of Safety Against Overturning = 2Factor of Safety Against Soil Bearing Capacity = 1

3.0 Design Assumptions1. The design is based on the assumed Geotechnical data furnished as above.2. Weight of top 0.5m of soil (on passive only) is neglected to account for future accidental, unplanned excavation.3. It is assumed that during Hydro test, soil behind thrust block is fully compacted so as to obtain a soil desity at

Ka =

Kp =

kN/m3

kN/m3

γc = kN/m3

γc' = kN/m3

γw' = kN/m3

kN/m2

Mz

FX

least equal to 95 percent of Modified Proctor test (ASTM D 1557).

4.0 Sectional Properties For Anchor Block

Pipe DiaDimensional Details Area Section Modulus

A B C D E H h

620mm 2.17 0.64 1.03 2 2.88 1.4 0.7 2.24 2.60 4.83 2.80 1.68 1.67

5.0 Stability Checks - For Sliding

Pipe DiaWeight Claculations Earth Pressure Calculations

Concrete Soil Above T.Block Total Weight *Active Pressure kN/m2 *Passive Pressure kN/m2Volume Weight Volume Weight P1 P2 P3 P4 P5 P6

620mm 6.11 118.69 0.00 0.00 118.69 0.00 6.00 7.07 0.00 54.00 63.60

Lateral Force along-x Resisting Force along-xFactor of Saftey Result > 4Fx Active Total

From Selfwt. TotalPipe Thrust Act. Soil Pre. (kN)

90.12 12.18 102.30 109.63 43.20 152.83 1.56 Unsafe

6.0 Stability Checks - For Overturning

Pipe DiaOverturning Moment Restoring moment-selfweight Restoring moment

Factor of Safety ResultDue to Fx Total Weight Lever arm Passive Total

620mm 63.08 5.88 68.96 118.69 1.20 142.20 52.90 195.10 2.83 O.K.

a1 a2 abase Iy ymax Zx=Ix/ymax

Passive Resistance

Due to active pre

Restoring Moment

E

A12B

CD

7.0 Stability Checks - For Soil Bearing

Allowable Gross Bearing Capacity = 204

Pipe Dia Thrust Fy

Soil Pressure due to Moment (Mz) Soil Press. due to MxResult Result

Due to Fx Total Mx

620mm 0.00 118.69 4.83 24.57 0.00 63.08 5.88 68.96 32.05 36.91 22.105 0.00 0 46.67 O.K. 2.46Small negative pressure neglected

Note:1. Net moment is calculated as below

a. If total induced moment is greater than moment due to passive force (passive force= total sliding force - frictional resistance of concrete)

Net moment = Mz - Mzp

Where Mz = Destabilising moment

Mzp = Restoring moment from passive force calculated as above.

b. If total induced moment is less than the moment due to passive soil, effect of moment is ignored in bearing pressure calculations.

8.0 Stability Checks - For Uplift

Pipe Dia Dry Concrete wt. Dry Soil weight Total Dry Weight Displaced water wt Factor of Safety Result

620mm 146.61 0 146.61 4 36.6530555746689

9.0 Reinforcement DesignReinforcement is required only for shrinkage purpose. As per BS-8007: Appendix-A-Figure A1.Following reinforcement is provided as skin rebars on the surface zone of the concrete in all faces.Minimum Reinforcement As = 0.13% of cross sectional areaSurface zone of concrete (For t>500mm) = 325 mm2(For thicknesses more than 500mm only 250thk shall be considered as effective)

Provided reinforcement (on all faces): T8 @ 150 c/c

Area of steel provided = 335> 325 O.K.

kN/m2

Total Weight (W)

kN

Base Area (m2)

Bearing Pressure

(P1)

Passive Pressure Moment

(Mzp)

Net moment

Soil Pressure

(P2)Max. Press. (P1+P2+P3)

Min. Press. (P1-P2-P3)Mz (Pipe

Thrust)Due to

active preSoil Press.

(P3)

mm2

SIZING CALCULATIONS OF THRUST BLOCKSProject Name: Project Number:Calc. By: Date: Chck'd By: Date: Sheet No. Revision

KEO International Consultants

1.0 Design DataAllowable soil bearing capacity SBC = 65 Kpa F.G.L. = 0.00

Soil Bulk Density γ = 18

Submerged Soil Density γ' = 8

Concrete Density 24

Submerged Concrete Density 14 -1

Density of water 10Diameter of the pipe D = 0.1 m 0.25

Test presuure p = 1200 0.75

Angle of bend θ = 15 ° -1.25Ground Water Table Level below Ground = 1 m

Unbalanced Thrust Force at Bent 0.32 kN 0.25 0.933 0.25

2.44 kN1.435

2.0 Factor of SafetyFactor of Safety Against Overturning = 2Factor of Safety Against Soil Bearing Capacity = 1

3.0 Design Assumptions1. The design is based on the assumed Geotechnical data furnished as above.2. Weight of top 0.5m of soil (on passive only) is neglected to account for future accidental, unplanned excavation.3. It is assumed that during Hydro test, soil behind thrust block is fully compacted so as to obtain a soil desity at

least equal to 95 percent of Modified Proctor test (ASTM D 1557).

kN/m3

kN/m3

γc = kN/m3

γc' = kN/m3

γw' = kN/m3

kN/m2

Rx =

RZ =

Rz

Rz

Rx

Rx

3.0 Approximate Size of Thrust Block

Length of the Thrust Block L = 1435 mmWidth of the Thrust Block B = 450 mmHeight of the Thrust Block H = 750 mm

4.0 Moment (Couple) in Thrust BlockThe forces in the upward bend and downward bend will cause a couple in the thrust blocks, which will be resisted by the weight of block.

Couple Moment in Thrust Block 2.36 kN.m

5.0 Resistance of Thrust Block

Weight of the Thrust Block 11.62 kN

Resisting Moment 8.34 kN.m

6.0 Stability Check of Thrust Block for Overturning

F.O.S. = 3.54 > 2 O.K.

7.0 Stability Check of Thrust Block for Soil Pressure

Moment of Inertia of Thrust Block 0.111

Couple Moment in Thrust Block 2.36 kN.mDistance to extreme fibre = y = 0.718 mStress at extreme fibre f = 15.26 kPa

Weight of Thrust Block per meter = 18

Weight of Soil 13.5

Maximum Soil Pressure = 46.76 < SBC = 65 O.K.

Minimum Soil Pressure = 2.74 > 0 O.K.

Mc =

WTh =

MR =

Factor Of Safety = Mc / MR

Iy = m4

Mc =

kN/m2

Wsoil = kN/m2

kN/m2

kN/m2