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GEO-TECHNICAL ENGINEERING CONSULTANTS
PROJECT : TAWEELAH POWER PLANT A2 LOCATION : TAWEELAH , ABU DHABI CONS CONSUL ULTA TANT NTS S : SE SEIM IMEN ENS S PILE BEARING CAPACITY IN WEAK ROCK INPUT
Pile Diameter Rock Socket Length Design UCS Base Design UCS Rock Socket Friction Angle ø Design RQD
600 3.00 1700 1700 38 60
mm m KN/m² KN/m² ° %
CALCULATION
Ultimate Pile Capacity Factor of Safety Safe Capacity of Pile
= = =
4337 KN 3 1446 446 KN
REFERENCE Pile Design and Construction Practice (Third Edition) by M J Tomlinson Section 4.7.1 & 4.7.3, Page 131,134 & 135
3
DESIGN CALCULATION
3.1
Loads The Loads on the foundations are as follows : Working Loads
Reduction Factor for joints Ultimate Pile Base Resistance
= =
50 % 4145 KN/m²
Pile Diameter
Base Resistance 0.6 0.8 0.9 1.0
1172 1831 2637 3255
kN kN kN kN
Use Pile Diameter 800 mm, Socket Length = 6.0 m Ultimate Capacity in Tension = Ultimate Capacity in Comp. =
2898 kN 4981 kN
2161.59 2454.05
3.5 Pile Reinforcement Design 3.5.1 Pile Stiffness Factor INPUT Pile Diameter Pile Depth Concrete Strength Cu Below water table y/n H
0.8 6 40 986 n 277
m m 2 N/mm 2 kN/m kN
Formulae Case - Cohesive Soil Case - Cohesionless Soil
1/4
R = (EI/K) 1/5 T = (EI/n h)
( 50% of UCS Value of 1972)
CALCULATION I = E = K nh = RESULT R T
= =
4
0.0201 m 2 28 kN/mm 2 12 MN/m MN/m
2.62 m m
6 m 2R = 5.23 m Embedded length of pile is greater than 2R
Pile embedded length =
o.k.
REFERENCE The above calculation is based on Pile Design & Construction Practice by M. J. Tomlinson, Chapter 6, item 6.3.1 3.5.2 Maximum Bending Moment along Depth =
H x M h x R = 277.47 x 0.5 x 2.62 = 363 kNm
The above calculation is based on Pile Design & Construction Practice by M. J. Tomlinson, Chapter 6, item 6.3.4 3.5.3 Steel Calculation for Compression & Bending (As Per CP110) Maxm. Axial Compression Load Maxm. Bending Moment Load Factor Ultimate Bending Moment ( M ) = 1.5 x 364 Pile Diameter ( h) Ultimate Axial Load ( N ) = 1.5 x 981.62 Concrete Cover Concrete Strength Steel Yield Strength hs = 800 - 2 x 75 hs/h = 650 / 800 2 N/h = 1472.43 x 1000 2 800 3 10 Mu / h = 545 x 800
% of the pile cross section area = Steel section area =
1.06 N/mm
0.5 0.5 % 2 2513 mm
(Steel Provided) = bar diameter number of bars area of steel available 3.5.4 Steel Calculation for Direct Tension
= = =
2
N/mm
3
(Asc/Ac) value obtained from graph (Using CP110 Part 3 1972) (Steel Required )=
= = = = = = = = = = = =
25 6 2 2945 mm
Ultimate Tension Tensile Strength of Steel (Steel Required ) =
= = =
2161.59 kN 2 460 N/mm 2 4699 mm
(Steel Provided) =
= = =
25 10 2 4909 mm
bar diameter number of bars area of steel available
3.5.5 Steel Calculation for Tension & Bending Tension Load Maxm. Bending Moment Pile Diameter Load Factor
f cd f yd m Where : T M Ac d f cd = f yd =
= = = = = = = = =
864.64 kN 363 kNm 800 mm 1.5
= = = =
T/(Ac . Fcd) M/(Ac . d . Fcd) Ast /Ac . fyd/fcd f cu x 0.85 / 1.5
0.114 0.060 0.22 (from Design Chart) 22667 kN/m2
= =
f y / 1.15
= 400000 kN/m2 1.5 for the Concrete ,1.15 for the Steel
= = = = = =
Tension Load on the Pile Maximum Bending Moment due to Lateral Load Area of Cross - Section of Pile Diameter of the Pile Design Strength of the Concrete = 0.85x fcu/ gm (BS8110) Design Strength of Steel = fy/ gm (BS8110)
(Steel Required ) = (Steel Provided) =
6266 mm bar diameter number of bars area of steel available
2
25 13 2 6381 mm
3.5.6 Steel Calculation for Crack Width Control Working Tension Allowable Tension in Steel (Steel Required ) = (Steel Provided) =
bar diameter number of bars area of steel available
=
864.64 2 130 N/mm 2 6651 mm
= = =
25 14 2 6872 mm
= =
( Please note that this consideration is not applicable as the ground water table was not encountered upto 20.0 m depth.)