68076493 Design Piles Foundation Rock (1)

G L 0 MP a G L 0 MP a G L 0 MP a

dep t h l ev e l uc s dep t h l ev e l uc s dep t h l ev e l uc s

11 . 5 - 11 . 500 1 . 02 11 . 3 - 11 . 300 2 . 16 11 . 7 - 11 . 700 0 . 98

12 . 6 - 12 . 600 1 . 96 12 - 12 . 000 1 . 99 12 . 9 - 12 . 900 2 . 61

13 . 3 - 13 . 300 7 . 34 13 - 13 . 000 4 . 2 13 . 8 - 13 . 800 4 . 61

14 . 2 - 14 . 200 4 . 21 14 . 5 - 14 . 500 5 . 61 14 . 5 - 14 . 500 1 . 35

15 - 15 . 000 5 . 19 15 . 3 - 15 . 300 1 . 08 15 . 9 - 15 . 900 1 . 41

16 . 3 - 16 . 300 2 . 42 16 . 6 - 16 . 600 1 . 86 16 . 8 - 16 . 800 6 . 31

17 . 1 - 17 . 100 1 . 21 17 . 5 - 17 . 500 0 . 75 17 . 3 - 17 . 300 1 . 73

18 - 18 . 000 1 . 08 18 . 2 - 18 . 200 8 . 31 18 - 18 . 000 2 . 16

19 . 5 - 19 . 500 1 . 69 19 . 6 - 19 . 600 1 . 31 19 . 5 - 19 . 500 4 . 18

Roc k l ev e l Roc k l ev e l Roc k l ev e l

11 - 11 . 000 11 - 11 . 000 11 - 11 . 000

Wat e r l ev e l Wat e r l ev e l Wat e r l ev e l

1 . 7 - 1 . 700 1 . 8 - 1 . 800 1 . 65 - 1 . 650

1020 1990 980

UC S S haft m in 980 ( f o r t oe l ev e l - 12 m)

Toe m in 1 .96 ( f o r t oe l ev e l - 12 m)

BH1 BH2 BH3

PFP/040/09/04/A012

100 TONS

CONTENTS:

1.0 GENERAL

2.0 PROPOSED PILE DETAILS

3.0 STRUCTURAL DESIGN CALCULATIONS OF THE PILE

3.1 MAXIMUM ALLAWABLE COMPRESSION LOAD

3.2 DESIGN REQUIREMENTS OF REINFORCEMENT

3.3 BENDING MOMENT CALCULATIONS IN PILE DUE TO H-FORCE &

CONSTRUCTIONAL ALLOWANCES

3.4 STRESS IN CONCRETE

3.5 CHECK FOR CLEAR SPACING

3.6 CHECK FOR BOND LENGTH

3.7 CHECK FOR STEEL IN TENSION

3.8 CHECK FOR SPACING OF STIRRUPS

4.0 GEOTECHNICAL DESIGN CALCULATIONS OF THE PILE

4.1 RESUME OF SOIL DATA

4.2 TOTAL PILE CAPACITY

4.2.1 CAPACITY OF PILE IN ROCK LAYER

4.2.2 SHAFT FRICTIONAL RESISTANCE OF PILE IN SOIL ABOVE ROCK LAYER

4.3 CALCULATION OF SETTLEMENT OF PILE

4.3.1 SETTLEMENT OF PILE SHAFT

4.3.2 SETTLEMENT OF PILE CAUSED BY THE LOAD AT END BEARING

4.3.3 SETTLEMENT OF PILE CAUSED BY THE LOAD SUBMITTED ALONG THE

PILE SHAFT

4.3.4 TOTAL PILE SETTLEMENT

1

DESIGN CALCULATIONS OF 500 MM DIA PILES,

Phoenix Foundation Piling LLC

April 22, 2009

(C) & 0 TONS (T)

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1.0 GENERAL

Project : Villas - 63 CFA PILES

Location : Plot No. 98 – Sector Z 22 - MBZ City

ABU DHABI

Owner : الحجري محمد سعيد سالم محمد السيد

PILING

Contractor : العامة للمقاوالت برنث بلى

Consultants : الهندسية لالستشارات العالمي التصميم مكتب

References : BS 8110 : 1997 ; Structural use of Concrete

BS 8004 : 1986 ; BS Code of practice for Foundations

Charts for design of circular columns to BS 8110

Principles of Foundation Engineering - Braja M Das

Pile Design and construction practice - M J Tomlinson, Third edition

Elements of Soil Mechanics for Civil and Mining Engineers

- By G N Smith

Pressure Meter and Foundation Engineering

- By F Baguelin, J F Jezequel, D H Shields

2.0 PROPOSED PILE DETAILS Ground Level ± 0.000 m G.Lvl

Pile Type : Bored Piles Using CFA Method 750 mm

max 1 m C.O.Lvl

Pile Diameter : below platform

Design Capacity : 0 Tons (T)

Number of Piles :

Pile Toe Level :

Pile length :

Cub Concrete Strength : 2

-7.6 m Rock Lvl Reinforcement :

Main Bars : 6 No: 460 N/mm2

Links : 8 mm @ 150mm & fy = 250 N/mm2 -8.6 m Toe Lvl

Cover : 75 mm

Tests :

Nbr of Working test : 2 Piles (1.5%)

Nbr of Integrity test : 63

Note: All Dimensions are in mm unless otherwise noted

C- Compression, S- Shear, T - Tension

2

100 Tons (C) &

-8.60 m

8.60 m

500 mm (Nominal)

Piles (100.0%)

8.0m Steel Bars

40.00 N/mm

63 Piles

16 mm & fy =


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3.0 STRUCTURAL DESIGN CALCULATIONS OF THE PILE 3.1 Maximum allawble compression load:

Allowing for eccentricity of loading due to deviations during construction, the

ultimate axial load should not exceed the value of N given by:

N = 0.4 fcu A c + 0.75 As fy (Eq 38 of BS 8110:1997)

fcu = 40 N/mm2, A c = 195143.1693 mm2

(Net Area)

fy = 460 N/mm2, A s = 1206.371579 mm2

N = 3538488.9 N Or 353.85 TONS

Load Factor : 1.4

Safe N = 252.75 TONS

Hence the pile is structurally safe to carry the load 100

3.2 Design Requirements of Reinforcement :

BS 8004:1986 Art 7.4.2.5.4 refers

OUT OF POSITION ALLOWED : 75

OUT OF PLUMB ALLOWED : 1:75

The reinforcement shall be designed for this Article requirement

: 50.00 kN

Horizontal load from plumb on the pile : 13.33 kN

(Including construction allowances)

B.M produced by eccentricity : 75.00 kN.m

3.3 Bending Moment calculations in Pile due to H-force and constructional allowances:

Since the piles are restrained by the pilecaps and Tie Beams the pile head shall be considered to be

restrained from rotational moment. Hence the moment on the pile occurs mainly due to horizontal

force at the pile head. Total horizontal force on the pile head (Ultimate) H = 83.33 kN

Elastic Analysis:

Reese and Matlock have established a series of curves for normally consolidated and cohesionless soils

for which the elastic modulus of the soil Es is assumed to increase from zero at the pile head in direct

proportion to the depth assuming that the pile behaves as an elastic beam on a soil which also behaves

elastically. Refer pages 219 to 223 of " Pile Design And Construction Practice by M J Tomlinson Third

Edition; 1987

Using the fixed Pile head equation (6.58) = MF = FmHT

MF = Bending Moment

Fm = Bending Moment Coefficient from figure 6.39b

T = Stiffness Factor

=5EI/nh

E = Reference: BS 8110:1997 Part 2, Table 7.2

= 28000 MN/m² or N/mm²

I = 0.003067962 m4

nh = Coefficient of subgrade modulus variation

= 24 MN/m3(Refer figure 6.20)

T = 1.3

Zmax = L/T

L = Pile length

Zmax = 6.62 7

3

H-force on the Pile (5.0% of the Vertical Load)


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Depth T Z=x/T Fm MF =FmHT

x (m) (m) (kN.m)

0 1.30 0.00 -0.93 -100.75

1.3 1.30 1.00 -0.05 -5.42

2.6 1.30 2.00 0.25 27.08

3.9 1.30 3.00 0.17 18.42

5.2 1.30 4.00 0.05 5.42

6.5 1.30 5.00 0.00 0.00

Therefore maximum bending moment on pile = Mmax =

75 + 100.75 = 175.75 kN.m

hs = 318 mm

318

500

For the Ultimate State Design apply a load factor of 1.4 for working load:

1.4 N M

h² h3

From Chart 13 for design of circular columns to BS 8110 , for this condition: Area of Steel required Areq = 0.40% (Asmin = 0.40%)

Area of Steel provided As = 0.61% Therefore safe

Proposed reinforcement:

Main Bars, 6 Nos, Dia: 16 mm

Area = 0.61% of concrete Therefore O.K.

Links 8 mm @ 150 mm

3.4 Stress in Concrete:

According to BS 8004:1986, Section 7.4.3.3.1 the working stress in compression should not exceed 25% of

the characteristic concrete strength at 28 days;

100 x 10000

p/4 x 500 ²

< 0.25 x fcu < 10 N/mm² Therefore safe

As an example of the foregoing calculations stresses,

the Moment at 5.2 M = 5.42 kN.m

Nc M f

Ac I 2

1000 x 103

5.42 x 106

x 500

p / 4 x 250000 3067961576 x 2

= 5.53 OR 4.65 5.09

As per BS 8004 Article 7.4.3.3.1:

these stresses are < 0.25 fcu or N/mm²

From the above results it can be inferred that stressses in the concrete are acceptable

4

s at 5.2 m =

= 5.60 1.41

N/mm2 Working stress =

10

N/mm², Which give sm =

x

Then hs /h =

5.092958179

=

=

=

±

0.64

; =

±


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3.5 Check for Clear Spacing:

For 6 bars of 16 mm dia, c.c spacing = 166.50

Therefore clear spacing is 150.50 mm

Art 3.12.11.2.4 of BS 8110 (Part 1) : 1997 max clear spacing is 300 mm

Thus 6 bars provided are adequate.

3.6 Check for Bond Length:

Table 3.27 of BS 8110:1997 shows the following values of anchorages

for various grades of concrete:

Grade Type 2 Deformed Bars

30 40 f

35 38 f

40 35 f

For fcu = 40 N/mm²

Anchorage length = 35 x 16

= = 560 mm

We propose 750 mm into the pile cap

3.7 Check for steel in tension:

As = 1206.3716 mm² for 6 Bars, Dia 16 mm

Ultimate Tensile Force = 1206.37 x 437 (460 X 0.95 = 437)

= 527184.38 N = 52.718 Tons

Load Factor = 1.4

Allowable Tensile Force = 37.66 0 Tons Therefore safe

3.8 Check for Spacing of Stirrups:

From Table 3.8 BS 8110 (Part 1:1997) , for fcu = 40 N/mm²

ds = 400.00 mm gm = 1.25

Area of Reinforcement Provided = mm2

Shear Stress = vc = 0.79 x (100 x As/(b x d))1/3 x (400/ds)1/4/gm

= 0.575 N/mm2 for concrete grade 25

vc = 0.575 0.673 N/mm2 for concrete grade 40

83.33 x 103

p/4 x 500 ²

As v < vc the permissible shear stress is more than the actual shear stress, No Shear reinforcement is not required.

however we provide nominal 8 mm links @ 150 mm

For this condition use the following equation:

Minimum Shear reinforcement required = Asv 0.4 bv sv / 0.95 fyv

Asv = 0.40 x 500 x 150 = 68.650 mm²

0.95 x 460< 100.53 mm² Therefore safe.

5

v = = 0.424 N/mm² (Ultimate)

Tons >

Working Shear Stress in pile = v =

1206.37

Hw

[40/25]1/3 =

p/4 xf ²


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4.0 GEOTECHNICAL DESIGN CALCULATIONS OF THE PILE:

4.1 RESUME OF SOIL DATA:

Soil Report by : GULF LABORATORY

Platform Level :

Platform Level

Cut-off Level : Cut-Off Level:

Min UCS of shaft : 1770 kN/m²

Min UCS at Toe : 2175 kN/m²

Zone of interest of reading for UCS Values at the Toe Level for

End Bearing Capacity [25% from shaft (0.5D) & 75% from Toe (1.5D)] Rock Level

Toe Level : -8.60 m Toe Level

Length of Piles:

4.2 Total Pile Capacity :

4.2.1 Pile Capacity in Rock Layer :

Taking the worst case, Rock Level : -7.60 m

UCS of rock at Toe of Pile : -8.60 m 2175 kN/m²UCS in Rock Socket : 1770 kN/m²

Length of Rock Socket : 1 m

Ultimate Bearing Capacity of Pile Qu

_a. 1st assumption:

Qu = Qb + Qs = Ab qb +As qs = Ab (1.3 C Nc + Nq s'v0 + 0.3 g' D Ng) + 1/2 Ks s'v0 tand As

Ab = Pile base area = 196349.5 mm²

C = Cohesion at base = ½ quc of UCS of Rock (but less than 0.46) = 0.46 N/mm²

(see annex - page 6 for Mudstone - to be at the safe side since the soil report give a higher value, we adopt 0.46 N/mm2)

Nc , Ng & Nq = Dimensionless Bearing Capacity Factors depneding of f (Tomlinson,3rd ed page 123)

Nc = 40 Nq = 20 Ng = 20 (see annex - page 4)

f = Angle of friction at the base pile level = 30 (see annex - pages 6 & 7 to take an idea)

s'v0 = Effective overburden pressure at base pile level = 76.00 kN/m² ,

g' = Average Effective unit weight of shaft pile in rock = 9.00 kN/m3 , (see annex - page 3 to take an idea)

D = Diameter of Piles = 500 mm

As = Area of Socket friction in rock = 1570796.327 mm²

Ks = Coefficient of the horizontal soil stress; d = Pile/Soil friction angle

Ks = K0 = (1-sinf) = 0.500 (Pile Design and construction practice - M J Tomlinson,

tand = tanf = 0.577 Third edition: Cast-in-place; concrete/sand)

qb = 25467 & qs = 10.96965511 kN/m2

max 1 m

It should be emphasized that the length of pile assumed in these calculations is based on Lower cut-off

levels, Loadings and results of tests run on a few boreholes carried out by a third party. At any rate such

information contained in the Boreholes results affecting the design may not be exactly representative of the

whole area and particularly that the hard strata reported may differ from pile location to the other. The

length of pile(s) shall be determined on site while boring by our supervisor on site as he is the best judge of

the soil conditions because he watching every bore all the time.Of course the attention of the Engineer's

Representative shall be drawn to each case as it arises and a decision taken regarding where to found the pile

in each case.

below platform

± 0.000 m

Reference: Braja M Das (Principles of Foundation Engineering - Pages 487 - 504) - Estimation of shaft & end

bearing according to TERZAGHI which can be calculated as follows:


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Qb = 196349.54 x 25.467 = 5000433.757 N 99.66%

Qs = 1570796.3 x 0.01096966 = 17231.09396 N 0.34%

Qu = 5017664.851 N = 501.77 Tons

6


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b. 2nd assumption:

qb = 2 Nf quc (4.26)

Where Nf = tan² (45 + f/2) For UCS of 2175 kN/m² ;

f = 30 °, Nf =

qb = 2 x 3.00 x 2175 = 13050.00 kN/m²

= 13.05 N/mm²

Shaft Frictional Resistance of Pile in Rock according to Tomlinson (After Williams & Pells):

qs = ab quc Where,

a = Rock Socket Reduction factor = 0.28 ;b = Rock Socket correction factor = 0.65 ; (Dependent on Mass factor/RQD)

Average RQD < 50%

quc = 1.770 N/mm² (Average UCS Value)

qs = 0.28 x 0.650 x 1.770 = 0.322 N/mm²

Shaft Frictional Resistance of Pile in Rock according to according to Tomlinson (After Rosenberg & Journeaux) :

qs = ab quc ; a = 0.20 ; b = 1.00 ;

qs = 0.2 x 1 x 1770 = 0.35 N/mm²

From the above comparative calculations it can be inferred that the minimum values are:

qb = 13.05 N/mm² ; qs = 0.32 N/mm²

Therefore

Qb = 196349.54 x 13.05 = 2562361.508 N 83.51%

Qs = 1570796.3 x 0.32 = 506016.3287 N 16.49%

Qu = 3068377.837 N = 306.84 Tons

From the above comparative calculations it can be inferred that the minimum value for bearing in rock is:

Qu = 306.84 Tons

4.2.2 Shaft Frictional Resistance of Pile in Soil above Rock Layer:

Friction angle of shaft in the Soil Layer : 36.0 see annex - page 1)

Length of Pile shaft in Soil Layer - 1m for Cap Pile : 6.6 m

Qs (S) = As qs = 1/2 Ks s'v0 tand As ; Where

s'v0 = Effective overburden pressure at the base of soil level = 76.00 kN/m² ,

Ks = Coefficient of the horizontal soil stress; d = Pile/Soil friction angle

As = Area of Socket friction = 10367255.76 mm²

qs = 1/2 Ks s'v0 tand As ; Where :

Ks = K0 = (1-sinf) = 0.412 (Pile Design and construction practice - M J Tomlinson,

tand = tanf = 0.727 Third edition: Cast-in-place; concrete/sand)

qs = 11.38 kN/m²

Qs (S) = 0.0113807 x 10367255.8 = 117986.4068 N = 11.79864068 Tons

Therefore, the total capacity of the pile is : Qu = 318.64 Tons

7

(Reference: Tomlinson's "Pile Design and Construction" Pages 131 - 136 Unit end bearing according to

Tomlinson can be calculated as follows:

3.00 ;


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In compression :

F.S = 3 ; Qallow = 106.21 Tons

> 100 Tons ; Therefore safeIn Tension :

; The weight of pile is not considered

F.S = 2.5 ; Qallow = 24.96 Tons

4.3 Calculation of Settlement of Pile :

Reference: "Principles of Foundation Engineering", second edition by Braja M Das.

Nomenclature:

S = Total pile settlement = S1 + S2 + S3

S1 = Settlement of pile shaft

S2 = Settlement of pile caused by the load at end bearing

S3 = Settlement of pile caused by the load transmitted along the pile shaft

4.3.1 Settlement of Pile shaft :

Settlement of pile shaft = S1 = (Qwp + x Qws )L

Ap Ep

Qwp = load carried by end bearing under working load condition = 376 kN

Qws = load carried by shaft friction under working load condition = 624 kN

Ap = area of pile cross section = 196349.54 mm²

L = Length of the pile from cut-off level = 7600.00 mm

Ep = Young's modulus of the pile material = 28 kN/mm²

Skin Friction resistance Distribution factor " x " = 0.5

x = 0.5 for uniform & parabolic ; x = 0.67 for triangular (Vesic, 1977)

Settlement of pile shaft = S1 = 0.952 mm

4.3.2 Settlement of pile caused by the load at end bearing :

S2 = qwp D x (1 - ms² ) Iwp

Es

D = diameter of pile = 500.0 mm

qwp = point load per unit area at pile point = 1914.95 kN/m²

Es = Young's modulus of rock at pile tip (see annex - pages 7, 9 & 10) = 350000 kN/m²

µs = Poisson's ratio of soil = 0.30 (see annex - page 11)

Iwp = influence factor = 0.88

S2 = Settlement of pile caused by the load at end bearing = 2.19 mm

4.3.3 Settlement of pile caused by the load transmitted along the pile shaft :

S3 = Qws x D x (1- µS2) Iws

pLe Es

p = perimeter of the pile = 1570.80 mm

Le = embedded length of pile = 1.00 m

Iws = influence factor = 2 + 0.35 Le / D (Vessic, 1977) = 3.36 mm

S3 = 1.74 mm

4.3.4 Total pile settlement :

Total settlement anticipated = S = S1 + S2 + S3 = 4.88 mm

Tons51Qu = Qs =


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The above figures, it must be appreciated, are calculated using data available from the soil report

and the actual conditions may vary taking into consideration the practical aspects and limitations

of the piling operation.

We cannot predict residual settlements as these should better be left to the actual testing of piles.

8


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ABU DHABI Plot No. 98 – Sector Z 22 - MBZ City

العامة للمقاوالت برنث بلى

الهندسية لالستشارات العالمي التصميم مكتب

PILE DESIGN

CONTRACTOR:

OWNER:

CONSULTANT:

PFP/040/09/04/A012JOB NUMBER:

PROJECT: Villas - 63 CFA PILES

LOCATION:

الحجري محمد سعيد سالم محمد السيد


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68076493 Design Piles Foundation Rock (1)

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