For Review

A 18 APR 2012 FOR REVIEW H.I.KIM J.B.SEO S.H.JU

Rev. DATE REASON FOR REVISION DRAWN CHECKED APPROVED

EMPLOYER Kenya Electricity Generating Company Ltd. Stima Plaza, Phase III Kolobot Road, P.O. Box 47936 00100 GPO, Nairobi, KENYA

Tel : +254 20 3666000 Fax : +254 20 248848

EMPLOYERS REPRESENTATIVE Sinclair Knight Merz Ltd Carlaw Park Commercial, 12-16 Nicholls Lane, Parnell, Auckland, NEW ZEALAND

Tel : +64 9 928 5500 Fax : +64 9 928 5501

EPC CONTRACTOR

Hyundai Engineering Co., Ltd. Hyundai 41 Tower, Mok 1-dong, Yangcheon-gu, Seoul, KOREA Tel : +82 2 2166 8573 Fax : +82 2 2643 0773

Toyota Tsusho Corporation 3-13, Konan 2-chome, Minato-ku, Tokyo, JAPAN

Tel : +81 3 4306 3200 Fax : +81 3 4306 8908

DRAWN BY DATE PROJECT

H.I.KIM 18 APR 2012 OLKARIA IV GEOTHERMAL POWER PLANT DESIGN BY DATE

E.J.LIM 18 APR 2012 TITLE & DESCRIPTION CHECK BY DATE DESIGN CALCULATION

BORED CAST IN-SITU PILE J.B.SEO 18 APR 2012

APPROVED BY DATE

S.H.JU 18 APR 2012

DRAWING SCALE DRAWING No. Rev.

NONE ZP00700-B2CE-ECG-CLC-0001 A

No. C O N T E N T S REF.

GENERAL

GeneralDesign Code & ReferenceDesign MethodDesign Data

GEOTECHNICAL PILE CAPACITY

BH-01 BH-02BH-04BH-05BH-06BH-08BH-09BH-10BH-11DBH-01DBH-02

SUMMARY

STRUCTURAL PILE DESIGN

REV. A TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

1.0

1.11.2

2.1

OLKARIA IV GEOTHERMAL POWER PLANT

1.31.4

2.0

2.62.7

2.5

2.10

2.22.32.4

2.8

4 0

2.9

3.0

2.11

STRUCTURAL PILE DESIGN

Cast In Situ PILE ( = 600, L = 15m ) CalculationCast In Situ PILE ( = 600, L = 18m ) CalculationCast In Situ PILE ( = 600, L = 20m ) CalculationCast In Situ PILE ( = 600, L = 25m ) Calculation

CONCLUSIONS

ATTACHMENT

Attachment-1: Borehole LocationAttachment-2: Borehole LogsAttachment-3: Pile Drawing

4.1

4.3

4.0

4.4

4.2

5.0

No. C A L C U L A T I O N REF.

1.0 GENERAL

1.1 General

For the Olkaria Geothermal Power Plant Project, pile foundation will be needed to support thebuildings and concrete structures depending on sub-soil condition.The allowable pile capacity was calculated base on soil investigation results which will be submittedas separate report(Doc No. ZP00700-B2CE-ECG-RPT-0001).In consideration of sub-soil condition, the various bored pile will be adopted.

1.2 Design Code & Reference

1) BS 8110 : Structural Use of Concrete2) BS 8004 : Foundations3) Principles of Foundation Engineering, 6th Edition, Braja M. Das, Thomson Learning, 20074) ZP00700-B2CE-ECG-DSC-0001: Design Criteria for Civil and Building Works5) FHWA-IF-99-025: Drilled Shafts: Construction Procedures and Design Methods

1.3 Design Criteria

1) Factor of Safety for End Bearing, FSbearing =2) Factor of Safety for Skin Friction, FSfriction =3) Factor of Safety for Lateral Load, FSlateral = 2.0

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.02.0

1.4 Design Data

1) Pile

- Type : Bored Pile - Dimension : D mm- Modulus of elasticity (Ep) : MPa = kN/m- Pile section (Ap) : m2

2) Concrete

- Strength at 28 days (fc') : MPa = kN/m (Cube strength)- Unit weight (c) : kg/m = kN/m3- Modulus of elasticity (Ec) : MPa = kN/m

3) Reinforcement steel (BS 4449)

- Minimum yield strength (fy) : MPa = kN/m- Modulus of elasticity (Es) : MPa = kN/m- Minimum cover for concrete protection : mm

25,000,000

2.0E+08

25

2.0E+05

25.0

0.28

460,000

25,000

25,000,000

60

460

25,000

25,000600

2,500

1/124

No. C A L C U L A T I O N REF.

2.0 GEOTECHNICAL PILE CAPACITY

2.1 BH-01

2.1.1 Subsoil Conditions

m G.W.T (m) =

~

Note: 1) "Cohesive" = clay or plastic sily, "Cohesionless" = sand, gravel or non-plastic silt

2) For cohesionless soil, we couldn't carry out unit weight tests because sampling of

from to0.0-3.0

-3.0-6.0-9.0

-11.0

Depth of layer (m)0.0

-25.0 184.8

4242 184.8

458

3524

154105.6

2213.0 35.2

79.218818

OLKARIA IV GEOTHERMAL POWER PLANT

13.0

BH-01 Pile Length =

-6.0-9.0

Su5)

18.0

45

2)

17.6-4.5 Cohesive

Cohesive(kN/m3)

13.013.0

-1.5

REV. A TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Soil type1) N3)

(kPa)(blow)centerN60

4)

(blow)

-7.5-10.0

-14.0-12.0

13.0Cohesive

CohesiveCohesiveCohesive 24

3513.0-11.0

-13.0-13.0-15.0

13.0Cohesive

Cohesive

-16.5-15.0 -18.0

cohesionless soil is very difficult. Therefore, we use typical soil properties in a naturalstate and conservartively select soil type.

- Type of soil = Loose angular-grained silty sand - Natural moisture content in a saturated sta = 25 % - Dry unit weight, d = 12 kN/m3

3) SPT N-value obtained from the field test Attachment-2

4) Corrected for hammer energy without overburden pressure correctionN60 = ( ER / 60 ) x N where, ER = SPT energy ratio = 60 %

5) Cohesion of so(take minimum value from following two equations)K N where K = 4 kN/m2 (Stroud, 1974)29 N0.72( Hara et al, 1971)

2/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.1.2 Allowable Compression Capacity (Reese and O'Neill, 1999)

1) Base Resistance for Compression Loading

a) Cohesive soil

qmax = Nc* x su = kPa

where, Nc* = bearing capacity factor =6.5 at su = 24 kPa8.0 at su = 48 kPa9.0 at su > 25 kPa

su = average undrained shear strength between the base of the pile andan elevation 2B below the base

b) Cohesionless soil

qmax = 57.5 N60 = kPa

where, N60 = average SPT blow count between the base of the pile and an elevation 2B below the base for condition which approximately60 percent of the potential energy of hammer is transferred

2) Side Resistance for Compression Loading

1663.2

0.0

9

a) Cohesive soil

fmax = x su

where, = a dimensionless correction coefficient defined as follows: = 0 between the ground surface and a depth of 1.5 m or to the

depth of seasonal moisture change, whichever is deeper = 0 for a distance of B (the diameter of the base) above the base = 0.55 for su / Pa 1.5 (Mpa) = 0.55 - 0.1 ( su / Pa - 1.5 ) for 1.5 su / Pa 2.5 (Mpa)where, Pa =the atmospheric pressure in the units being used

(e.g., 101 kPa in the SI system).

b) Cohesionless soil

fmax = x 'v

where, 'v = vertical effective stress at the middle of layer

= dimensionless correction factor defined as follows:in sands

= 1.5 - 0.245 z0.5 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

in gravelly sands or gravels = 2.0 - 0.15 z0.75 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

where, z = vertical distance from the ground surface to the middle of layer (in meters)

3/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Note: 1) Thickness of layer.

4) Allowable compression capacity

Qa = ( qmax x Ap ) / FSbearing + Qs / FSfriction = kN863.8

0.00.0 0.00 0.0 0.010 0.0

(kN)

0.0

317.9

68.4

3.83.8

1257.4

5

154.0 0.55184.8

822.0

(kPa)(blow)

35

79.224

35.2

44.7

Qs

0.55 12.1 3.0

0.55 164.22.0219.0

43.6109.53

0.00

21 4

LayerNo.

N60

38.3

5.73.831.9

0.55 58.1 2.0

19.4

6

As(m2)1.9 18.20.55

105.6

14.4

5

su

0.0

4

7 42

18

8 0

84.3 2.03.8 360.2

0.00.0

0.052.6 0.52

3.82.00.000.0 0.00 0.0 0.0 0.00.0

fmax

23.9 0.55

4.85.7

(kPa)Thick.1)v'

(kPa) (m)17.6

3.0

sum

9 0 0.000.00

0.00

1.04

9.7

2.00.580.50

1.0

95.5

0.320.330.440.87

4/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.1.3 Allowable Tension Capacity (Reese and O'Neill, 1999)

1) Base resistance for uplift loading

qmax (uplift)1) = 0

Note: 1) qmax should be taken as zero for uplift loading unless experience or load testing atthe construction site can show that suction between the bottom of the drilled shaftand the soil can be predicted reliably or the drilled shaft has a bell.

2) Side resistance for uplift loading

fmax (uplift) = x fmax (compression)

where, = for Cohesive soil = for Cohesionless soil

68.4109.5

18.2

164.2219.0317.91.00317.9

1.001.001.001.00

CohesiveCohesive

219.0

Cohesive

Soil typeQs

(kN)

1.000.75

Ts(kN)

Cohesive

18.268.4

109.5

164.2

Cohesive

Cohesive 1.00

sum =

3) Allowable tension capacity

Ta = ( Tp + Ts ) / FSfriction = kN628.7

360.20.00.00.0

1257.40.00

0.00.00.0

1.000.000.00

360.2

00

0Cohesive

5/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.1.4 Allowable Lateral Load Capacity (Broms' Method)

1) Coefficient of horizontal subgrade reaction

a) General soil type1) :

Note: 1) Determine the general soil type within the critical depth below the grond FHWA-HI-97-013surface (about 4 or 5 pile diameters). Chapter 9

b) Average soil parameter with the critical depth

su = kPa for Cohesive soil

= deg for Cohesionless soil

where, = Internal friction angle correleted by Ozaki's equation1)

Note: 1) = ( 20 N )0.5 + 15

c) Coefficient of horizontal subgrade reaction, Kh

Kh = n1 x n2 x 80 x qu / b = kN/m3 for Cohesive soil

where, qu = Unconfined compressive strength = kPa35.2

17.6

0.0

1727.1

Cohesive

b = Width or diameter of pile = m

n1 = Empirical coefficients dependent on qu =n1 = 0.32 for less than 48 kPan1 = 0.36 for 48 to 191 kPan1 = 0.40 for more than 191 kPa

n2 = Empirical coefficient dependent on pile material =n2 = 1.00 for steeln2 = 1.15 for concreten2 = 1.30 for wood

Kh = kN/m3 for Cohesionless soil

where, above ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

below ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

1900

1086

0.6

5429

0.32

1.15

10857

0.0

814317644

6/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2) Pile parameters

a) Modulus of elasticity, E = Mpa

b) Moment of inertia, I = m4

c) Section modulus, S = m3

d) Embedded pile length D = m

e) Diameter or width, b = m

f) Ultimate compression strength for concrete, f'c = Mpa

g) Eccentricity of applied load for free-headed piles, ec =

h) Resisting moment of pile for concrete piles, My = fc' S kN-m

3) Dimensionless length factor

a) Stiffness factor

h = ( Kh b / 4EI )0.25 = m-1 for Cohesive soil,

25.0

530.1

0.0

0.20

0.60

18.0

25000

0.0064

0.0212

= (Kh / EI)0.20 = m-1 for Cohesionless soil,

b) Length factor

h D = for Cohesive soil,

D = for Cohesionless soil,

4) Determine if the pile is long or short

a) Cohesive soil:

where, h D > 2.25 (long pile)h D < 2.25 (short pile)

b) Cohesionless soil:

where, D > 4.0 (long pile) D < 2.0 (short pile)2.0 < D < 4.0 (intermediate pile)

Soil type =Pile type =

3.62

0.00

Cohesivelong pile

0.00

short pile

long pile

7/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

5) Soil parameters

cu = kPa

where, cu = cohesion for cohesive soil

6) Ultimate lateral load (Cohesive, long pile)

My/cub3 =

ec/b =Qu/cub

2 = from the below chartQu = kN

17.6

0139.5

57.0361.2

7) Allowable lateral load capacity

Hu = kN

Ha = Hu / FSlateral = kN180.6

361.2

8/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.1.5 PILE SETTLEMENT

Elastic Settlement of Pile

se(1) = (Qwp + Qws) x L / (Ap x Ep)

where, Qwp = load carried at the pile point under working load conditionQws = load carried by frictional resistance under working load conditionAp = area of cross section of pileL = length of pile Ep = modulus of elasticity of the pile material = coefficient which will depend on the nature of the distribution of the unit

friction resistance along the pile shaftconservatively, 0.5

Settlement of Pile Caused by the Load at the Pile Tip (Vesic, 1977)

0.5 1.67Design-N 444.7 419.1 0.28 18.0 25000(mm)

Qws Ap L Ep se(1)(kN) (m2) (m) (Mpa)

BoreholeQwp(kN)

se(2) = (Qwp x Cp) / (D x qp)

where, qp = ultimate point resistance of the pileCp = an empirical coefficient

Settlement of Pile Caused by the Load Transmitted along the Pile Shaft (Vesic, 1977)

se(3) = (QwS x CS) / (L x qp)

where, Cs = an empirical constant = [ 0.93 + 0.16 (L / D)0.5 ] Cp

Design-N 18.0 419.1 1663.2 0.07 1.01

Csse(3)

(mm)Borehole

L Qws qp(m) (kN) (kN/m2)

Design-N 600 444.7 1663.2 0.04 17.82

Cpse(2)

(mm)Borehole

D Qwp qp(mm) (kN) (kN/m2)

Silt (dense to loose) 0.03 - 0.05 0.09 - 0.12Clay (Stiff to Soft) 0.02 - 0.03 0.03 - 0.06

Sand (dense to loose) 0.02 - 0.04 0.09 - 0.18Type of soil Driven piles Bored piles

9/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Total Settlement of Pile

se = se(1) + se(2) + se(3)

where, se(1) = elastic settlement of pilese(2) = settlement of pile caused by the load at the pile tipse(3) = settlement of pile caused by the load transmitted along the pile shaft

Note: 1) se(allowable) = mmEurocode 7: Geotechnical design, Annex H, For normal structures with isolated foundations, total settlements up to 50mm areoften acceptable.

(mm) (mm) (mm) (mm)

50.0

Boreholese(1) se(2) se(3) se Check1)

Design-N 1.67 17.82 1.01 20.50 O.K

10/124

No. C A L C U L A T I O N REF.

2.2 BH-02

2.2.1 Subsoil Conditions

m G.W.T (m) =

~

Note: 1) "Cohesive" = clay or plastic sily, "Cohesionless" = sand, gravel or non-plastic silt

2) For cohesionless soil, we couldn't carry out unit weight tests because sampling of

-15.0 Cohesive 70.4

16 70.4-13.0 -15.0 -14.0 Cohesive 13.0 16 16 70.4-11.0 -13.0 -12.0 Cohesive 13.0 16

25 110-8.0 -11.0 -9.5 Cohesive 13.0 21 21 92.4-6.0 -8.0 -7.0 Cohesive 13.0 25

154-3.0 -6.0 -4.5 Cohesive 13.0 31 31 136.4

(blow) (blow) (kPa)0.0 -3.0 -1.5 Cohesive 13.0 35 35

Depth of layer (m)Soil type1)

2) N3) N604) su

5)

from to center (kN/m3)

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

BH-02 Pile Length = 15.0 0.0

cohesionless soil is very difficult. Therefore, we use typical soil properties in a naturalstate and conservartively select soil type.

- Type of soil = Loose angular-grained silty sand - Natural moisture content in a saturated sta = 25 % - Dry unit weight, d = 12 kN/m3

3) SPT N-value obtained from the field test Attachment-2

4) Corrected for hammer energy without overburden pressure correctionN60 = ( ER / 60 ) x N where, ER = SPT energy ratio = 60 %

5) Cohesion of so(take minimum value from following two equations)K N where K = 4 kN/m2 (Stroud, 1974)29 N0.72( Hara et al, 1971)

11/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.2.2 Allowable Compression Capacity (Reese and O'Neill, 1999)

1) Base Resistance for Compression Loading

a) Cohesive soil

qmax = Nc* x su = kPa

where, Nc* = bearing capacity factor =6.5 at su = 24 kPa8.0 at su = 48 kPa9.0 at su > 25 kPa

su = average undrained shear strength between the base of the pile andan elevation 2B below the base

b) Cohesionless soil

qmax = 57.5 N60 = kPa

where, N60 = average SPT blow count between the base of the pile and an elevation 2B below the base for condition which approximately60 percent of the potential energy of hammer is transferred

2) Side Resistance for Compression Loading

0.0

9

633.6

a) Cohesive soil

fmax = x su

where, = a dimensionless correction coefficient defined as follows: = 0 between the ground surface and a depth of 1.5 m or to the

depth of seasonal moisture change, whichever is deeper = 0 for a distance of B (the diameter of the base) above the base = 0.55 for su / Pa 1.5 (Mpa) = 0.55 - 0.1 ( su / Pa - 1.5 ) for 1.5 su / Pa 2.5 (Mpa)where, Pa =the atmospheric pressure in the units being used

(e.g., 101 kPa in the SI system).

b) Cohesionless soil

fmax = x 'v

where, 'v = vertical effective stress at the middle of layer

= dimensionless correction factor defined as follows:in sands

= 1.5 - 0.245 z0.5 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

in gravelly sands or gravels = 2.0 - 0.15 z0.75 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

where, z = vertical distance from the ground surface to the middle of layer (in meters)

12/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Note: 1) Thickness of layer.

4) Allowable compression capacity

Qa = ( qmax x Ap ) / FSbearing + Qs / FSfriction = kN

1708.4

943.8

sum0.0 0.0 0.0 0.010 0 0.0 0.00 0.0 0.00

0.09 0 0.0 0.00 0.0 0.00 0.0 0.0 0.00.0 0.0 0.0 0.08 0 0.0 0.00 0.0 0.00

0.07 0 0.0 0.00 0.0 0.00 0.0 0.0 0.038.7 2.0 3.8 146.06 16 70.4 0.62 44.7 0.55

146.05 16 70.4 0.69 38.3 0.55 38.7 2.0 3.850.8 3.0 5.7 287.44 21 92.4 1.04 30.3 0.55

228.13 25 110.0 1.42 22.3 0.55 60.5 2.0 3.875.0 3.0 5.7 424.22 31 136.4 0.98 14.4 0.55

476.81 35 154.0 1.20 4.8 0.55 84.3 3.0 5.7(blow) (kPa) (kPa) (m) (m2)

As Qs(kN)

LayerNo.

N60 su v'(kPa)

fmax Thick.1)

13/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.2.3 Allowable Tension Capacity (Reese and O'Neill, 1999)

1) Base resistance for uplift loading

qmax (uplift)1) = 0

Note: 1) qmax should be taken as zero for uplift loading unless experience or load testing atthe construction site can show that suction between the bottom of the drilled shaftand the soil can be predicted reliably or the drilled shaft has a bell.

2) Side resistance for uplift loading

fmax (uplift) = x fmax (compression)

where, = for Cohesive soil = for Cohesionless soil

Cohesive 146.0 1.00 146.0

Cohesive 287.4 1.00 287.4Cohesive 146.0 1.00 146.0

Cohesive 424.2 1.00 424.2Cohesive 228.1 1.00 228.1

(kN)Cohesive 476.8 1.00 476.8

1.000.75

Soil typeQs Ts

(kN)

sum =

3) Allowable tension capacity

Ta = ( Tp + Ts ) / FSfriction = kN854.2

0 0.0 0.00 0.01708.4

0 0.0 0.00 0.00 0.0 0.00 0.0

0 0.0 0.00 0.0

14/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.2.4 Allowable Lateral Load Capacity (Broms' Method)

1) Coefficient of horizontal subgrade reaction

a) General soil type1) :

Note: 1) Determine the general soil type within the critical depth below the grond FHWA-HI-97-013surface (about 4 or 5 pile diameters). Chapter 9

b) Average soil parameter with the critical depth

su = kPa for Cohesive soil

= deg for Cohesionless soil

where, = Internal friction angle correleted by Ozaki's equation1)

Note: 1) = ( 20 N )0.5 + 15

c) Coefficient of horizontal subgrade reaction, Kh

Kh = n1 x n2 x 80 x qu / b = kN/m3 for Cohesive soil

where, qu = Unconfined compressive strength = kPa

154

0.0

18891

308

Cohesive

b = Width or diameter of pile = m

n1 = Empirical coefficients dependent on qu =n1 = 0.32 for less than 48 kPan1 = 0.36 for 48 to 191 kPan1 = 0.40 for more than 191 kPa

n2 = Empirical coefficient dependent on pile material =n2 = 1.00 for steeln2 = 1.15 for concreten2 = 1.30 for wood

Kh = kN/m3 for Cohesionless soil

where, above ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

below ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

542910857

1.15

0.0

19008143

17644

1086

0.6

0.4

15/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2) Pile parameters

a) Modulus of elasticity, E = Mpa

b) Moment of inertia, I = m4

c) Section modulus, S = m3

d) Embedded pile length D = m

e) Diameter or width, b = m

f) Ultimate compression strength for concrete, f'c = Mpa

g) Eccentricity of applied load for free-headed piles, ec =

h) Resisting moment of pile for concrete piles, My = fc' S kN-m

3) Dimensionless length factor

a) Stiffness factor

h = ( Kh b / 4EI )0.25 = m-1 for Cohesive soil,

0.60

25.0

0.0

530.1

0.37

25000

0.0064

0.0212

15.0

= (Kh / EI)0.20 = m-1 for Cohesionless soil,

b) Length factor

h D = for Cohesive soil,

D = for Cohesionless soil,

4) Determine if the pile is long or short

a) Cohesive soil:

where, h D > 2.25 (long pile)h D < 2.25 (short pile)

b) Cohesionless soil:

where, D > 4.0 (long pile) D < 2.0 (short pile)2.0 < D < 4.0 (intermediate pile)

Soil type =Pile type =

5.48

0.00

long pile

short pile

Cohesivelong pile

0.00

16/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

5) Soil parameters

cu = kPa

where, cu = cohesion for cohesive soil

6) Ultimate lateral load (Cohesive, long pile)

My/cub3 =

ec/b =Qu/cub

2 = from the below chartQu = kN

154

15.90

14.0776.2

7) Allowable lateral load capacity

Hu = kN

Ha = Hu / FSlateral = kN

776.2

388.1

17/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.2.5 PILE SETTLEMENT

Elastic Settlement of Pile

se(1) = (Qwp + Qws) x L / (Ap x Ep)

where, Qwp = load carried at the pile point under working load conditionQws = load carried by frictional resistance under working load conditionAp = area of cross section of pileL = length of pile Ep = modulus of elasticity of the pile material = coefficient which will depend on the nature of the distribution of the unit

friction resistance along the pile shaftconservatively, 0.5

Settlement of Pile Caused by the Load at the Pile Tip (Vesic, 1977)

Design-N 374.3 569.5 0.28 15.0 25000

se(1)(m2) (m) (Mpa) (mm)

BoreholeQwp Qws Ap L Ep(kN) (kN)

0.5 1.40

se(2) = (Qwp x Cp) / (D x qp)

where, qp = ultimate point resistance of the pileCp = an empirical coefficient

Settlement of Pile Caused by the Load Transmitted along the Pile Shaft (Vesic, 1977)

se(3) = (QwS x CS) / (L x qp)

where, Cs = an empirical constant = [ 0.93 + 0.16 (L / D)0.5 ] Cp

Type of soil Driven piles Bored pilesSand (dense to loose) 0.02 - 0.04 0.09 - 0.18

Clay (Stiff to Soft) 0.02 - 0.03 0.03 - 0.06Silt (dense to loose) 0.03 - 0.05 0.09 - 0.12

BoreholeD Qwp qp Cp

se(2)(mm) (kN) (kN/m2) (mm)

Design-N 600 374.3 1663.2 0.04 15.00

BoreholeL Qws qp Cs

se(3)(m)

Design-N 15.0 569.5 1663.2 0.07 1.58(kN) (kN/m2) (mm)

18/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Total Settlement of Pile

se = se(1) + se(2) + se(3)

where, se(1) = elastic settlement of pilese(2) = settlement of pile caused by the load at the pile tipse(3) = settlement of pile caused by the load transmitted along the pile shaft

Note: 1) se(allowable) = mmEurocode 7: Geotechnical design, Annex H, For normal structures with isolated foundations, total settlements up to 50mm areoften acceptable.

se(1) se(2) se(3) se Check1)

Design-N 1.40 15.00 1.58 17.98

Borehole

O.K

50.0

(mm) (mm) (mm) (mm)

19/124

No. C A L C U L A T I O N REF.

2.3 BH-04

2.3.1 Subsoil Conditions

m G.W.T (m) =

~

Note: 1) "Cohesive" = clay or plastic sily, "Cohesionless" = sand, gravel or non-plastic silt

2) For cohesionless soil, we couldn't carry out unit weight tests because sampling of

-20.0 Cohesive 110

110Cohesive 13.0 16 16 70.4

-19.0 Cohesive 13.0 25 25

9 39.6-13.0 -15.0 -14.0 Cohesive 13.0 10 10 44-11.0 -13.0 -12.0 Cohesive 13.0 9

9 39.6-8.0 -11.0 -9.5 Cohesive 13.0 4 4 17.6-6.0 -8.0 -7.0 Cohesive 13.0 9

30.8-3.0 -6.0 -4.5 Cohesive 13.0 16 16 70.4

(blow) (blow) (kPa)0.0 -3.0 -1.5 Cohesive 13.0 7 7

Depth of layer (m)Soil type1)

2) N3) N604) su

5)

from to center (kN/m3)

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

BH-04 Pile Length = 20.0 0.0

-18.0 -20.0-15.0 -18.0 -16.5

cohesionless soil is very difficult. Therefore, we use typical soil properties in a naturalstate and conservartively select soil type.

- Type of soil = Loose angular-grained silty sand - Natural moisture content in a saturated sta = 25 % - Dry unit weight, d = 12 kN/m3

3) SPT N-value obtained from the field test Attachment-2

4) Corrected for hammer energy without overburden pressure correctionN60 = ( ER / 60 ) x N where, ER = SPT energy ratio = 60 %

5) Cohesion of so(take minimum value from following two equations)K N where K = 4 kN/m2 (Stroud, 1974)29 N0.72( Hara et al, 1971)

20/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.3.2 Allowable Compression Capacity (Reese and O'Neill, 1999)

1) Base Resistance for Compression Loading

a) Cohesive soil

qmax = Nc* x su = kPa

where, Nc* = bearing capacity factor =6.5 at su = 24 kPa8.0 at su = 48 kPa9.0 at su > 25 kPa

su = average undrained shear strength between the base of the pile andan elevation 2B below the base

b) Cohesionless soil

qmax = 57.5 N60 = kPa

where, N60 = average SPT blow count between the base of the pile and an elevation 2B below the base for condition which approximately60 percent of the potential energy of hammer is transferred

2) Side Resistance for Compression Loading

0.0

9

990.0

a) Cohesive soil

fmax = x su

where, = a dimensionless correction coefficient defined as follows: = 0 between the ground surface and a depth of 1.5 m or to the

depth of seasonal moisture change, whichever is deeper = 0 for a distance of B (the diameter of the base) above the base = 0.55 for su / Pa 1.5 (Mpa) = 0.55 - 0.1 ( su / Pa - 1.5 ) for 1.5 su / Pa 2.5 (Mpa)where, Pa =the atmospheric pressure in the units being used

(e.g., 101 kPa in the SI system).

b) Cohesionless soil

fmax = x 'v

where, 'v = vertical effective stress at the middle of layer

= dimensionless correction factor defined as follows:in sands

= 1.5 - 0.245 z0.5 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

in gravelly sands or gravels = 2.0 - 0.15 z0.75 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

where, z = vertical distance from the ground surface to the middle of layer (in meters)

21/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Note: 1) Thickness of layer.

4) Allowable compression capacity

Qa = ( qmax x Ap ) / FSbearing + Qs / FSfriction = kN

1072.0

675.9

sum0.0 0.0 0.0 0.03 0 0.0 0.00 0.0 0.00

0.03 0 0.0 0.00 0.0 0.00 0.0 0.0 0.060.5 2.0 3.8 228.13 25 110.0 0.72 60.6 0.55

219.03 16 70.4 0.54 52.6 0.55 38.7 3.0 5.724.2 2.0 3.8 91.23 10 44.0 0.39 44.7 0.55

82.13 9 39.6 0.39 38.3 0.55 21.8 2.0 3.89.7 3.0 5.7 54.73 4 17.6 0.25 30.3 0.55

82.13 9 39.6 0.51 22.3 0.55 21.8 2.0 3.838.7 3.0 5.7 219.02 16 70.4 1.05 14.4 0.55

95.81 7 30.8 0.56 4.8 0.55 16.9 3.0 5.7(blow) (kPa) (kPa) (m) (m2)

As Qs(kN)

LayerNo.

N60 su v'(kPa)

fmax Thick.1)

22/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.3.3 Allowable Tension Capacity (Reese and O'Neill, 1999)

1) Base resistance for uplift loading

qmax (uplift)1) = 0

Note: 1) qmax should be taken as zero for uplift loading unless experience or load testing atthe construction site can show that suction between the bottom of the drilled shaftand the soil can be predicted reliably or the drilled shaft has a bell.

2) Side resistance for uplift loading

fmax (uplift) = x fmax (compression)

where, = for Cohesive soil = for Cohesionless soil

Cohesive 91.2 1.00 91.2

Cohesive 54.7 1.00 54.7Cohesive 82.1 1.00 82.1

Cohesive 219.0 1.00 219.0Cohesive 82.1 1.00 82.1

(kN)Cohesive 95.8 1.00 95.8

1.000.75

Soil typeQs Ts

(kN)

sum =

3) Allowable tension capacity

Ta = ( Tp + Ts ) / FSfriction = kN536.0

0 0.0 0.00 0.01072.0

Cohesive 228.1 1.00 228.10 0.0 0.00 0.0

Cohesive 219.0 1.00 219.0

23/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.3.4 Allowable Lateral Load Capacity (Broms' Method)

1) Coefficient of horizontal subgrade reaction

a) General soil type1) :

Note: 1) Determine the general soil type within the critical depth below the grond FHWA-HI-97-013surface (about 4 or 5 pile diameters). Chapter 9

b) Average soil parameter with the critical depth

su = kPa for Cohesive soil

= deg for Cohesionless soil

where, = Internal friction angle correleted by Ozaki's equation1)

Note: 1) = ( 20 N )0.5 + 15

c) Coefficient of horizontal subgrade reaction, Kh

Kh = n1 x n2 x 80 x qu / b = kN/m3 for Cohesive soil

where, qu = Unconfined compressive strength = kPa

30.8

0.0

3400.3

61.6

Cohesive

b = Width or diameter of pile = m

n1 = Empirical coefficients dependent on qu =n1 = 0.32 for less than 48 kPan1 = 0.36 for 48 to 191 kPan1 = 0.40 for more than 191 kPa

n2 = Empirical coefficient dependent on pile material =n2 = 1.00 for steeln2 = 1.15 for concreten2 = 1.30 for wood

Kh = kN/m3 for Cohesionless soil

where, above ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

below ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

542910857

1.15

0.0

19008143

17644

1086

0.6

0.36

24/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2) Pile parameters

a) Modulus of elasticity, E = Mpa

b) Moment of inertia, I = m4

c) Section modulus, S = m3

d) Embedded pile length D = m

e) Diameter or width, b = m

f) Ultimate compression strength for concrete, f'c = Mpa

g) Eccentricity of applied load for free-headed piles, ec =

h) Resisting moment of pile for concrete piles, My = fc' S kN-m

3) Dimensionless length factor

a) Stiffness factor

h = ( Kh b / 4EI )0.25 = m-1 for Cohesive soil,

0.60

25.0

0.0

530.1

0.24

25000

0.0064

0.0212

20.0

= (Kh / EI)0.20 = m-1 for Cohesionless soil,

b) Length factor

h D = for Cohesive soil,

D = for Cohesionless soil,

4) Determine if the pile is long or short

a) Cohesive soil:

where, h D > 2.25 (long pile)h D < 2.25 (short pile)

b) Cohesionless soil:

where, D > 4.0 (long pile) D < 2.0 (short pile)2.0 < D < 4.0 (intermediate pile)

Soil type =Pile type =

4.76

0.00

long pile

short pile

Cohesivelong pile

0.00

25/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

5) Soil parameters

cu = kPa

where, cu = cohesion for cohesive soil

6) Ultimate lateral load (Cohesive, long pile)

My/cub3 =

ec/b =Qu/cub

2 = from the below chartQu = kN

30.8

79.70

40.0443.5

7) Allowable lateral load capacity

Hu = kN

Ha = Hu / FSlateral = kN

443.5

221.8

26/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.3.5 PILE SETTLEMENT

Elastic Settlement of Pile

se(1) = (Qwp + Qws) x L / (Ap x Ep)

where, Qwp = load carried at the pile point under working load conditionQws = load carried by frictional resistance under working load conditionAp = area of cross section of pileL = length of pile Ep = modulus of elasticity of the pile material = coefficient which will depend on the nature of the distribution of the unit

friction resistance along the pile shaftconservatively, 0.5

Settlement of Pile Caused by the Load at the Pile Tip (Vesic, 1977)

Design-N 318.6 357.3 0.28 20.0 25000

se(1)(m2) (m) (Mpa) (mm)

BoreholeQwp Qws Ap L Ep(kN) (kN)

0.5 1.41

se(2) = (Qwp x Cp) / (D x qp)

where, qp = ultimate point resistance of the pileCp = an empirical coefficient

Settlement of Pile Caused by the Load Transmitted along the Pile Shaft (Vesic, 1977)

se(3) = (QwS x CS) / (L x qp)

where, Cs = an empirical constant = [ 0.93 + 0.16 (L / D)0.5 ] Cp

Type of soil Driven piles Bored pilesSand (dense to loose) 0.02 - 0.04 0.09 - 0.18

Clay (Stiff to Soft) 0.02 - 0.03 0.03 - 0.06Silt (dense to loose) 0.03 - 0.05 0.09 - 0.12

BoreholeD Qwp qp Cp

se(2)(mm) (kN) (kN/m2) (mm)

Design-N 600 318.6 990.0 0.04 21.46

BoreholeL Qws qp Cs

se(3)(m)

Design-N 20.0 357.3 990.0 0.07 1.34(kN) (kN/m2) (mm)

27/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Total Settlement of Pile

se = se(1) + se(2) + se(3)

where, se(1) = elastic settlement of pilese(2) = settlement of pile caused by the load at the pile tipse(3) = settlement of pile caused by the load transmitted along the pile shaft

Note: 1) se(allowable) = mmEurocode 7: Geotechnical design, Annex H, For normal structures with isolated foundations, total settlements up to 50mm areoften acceptable.

se(1) se(2) se(3) se Check1)

Design-N 1.41 21.46 1.34 24.20

Borehole

O.K

50.0

(mm) (mm) (mm) (mm)

28/124

No. C A L C U L A T I O N REF.

2.4 BH-05

2.4.1 Subsoil Conditions

m G.W.T (m) =

~

Note: 1) "Cohesive" = clay or plastic sily, "Cohesionless" = sand, gravel or non-plastic silt

2) For cohesionless soil, we couldn't carry out unit weight tests because sampling of

-18.0 Cohesive 66

Cohesive 13.0 15 15 66

17 74.8-13.0 -15.0 -14.0 Cohesive 13.0 14 14 61.6-11.0 -13.0 -12.0 Cohesive 13.0 17

30 132-8.0 -11.0 -9.5 Cohesive 13.0 11 11 48.4-6.0 -8.0 -7.0 Cohesive 13.0 30

132-3.0 -6.0 -4.5 Cohesive 13.0 9 9 39.6

(blow) (blow) (kPa)0.0 -3.0 -1.5 Cohesive 13.0 30 30

Depth of layer (m)Soil type1)

2) N3) N604) su

5)

from to center (kN/m3)

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

BH-05 Pile Length = 18.0 0.0

-15.0 -18.0 -16.5

cohesionless soil is very difficult. Therefore, we use typical soil properties in a naturalstate and conservartively select soil type.

- Type of soil = Loose angular-grained silty sand - Natural moisture content in a saturated sta = 25 % - Dry unit weight, d = 12 kN/m3

3) SPT N-value obtained from the field test Attachment-2

4) Corrected for hammer energy without overburden pressure correctionN60 = ( ER / 60 ) x N where, ER = SPT energy ratio = 60 %

5) Cohesion of so(take minimum value from following two equations)K N where K = 4 kN/m2 (Stroud, 1974)29 N0.72( Hara et al, 1971)

29/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.4.2 Allowable Compression Capacity (Reese and O'Neill, 1999)

1) Base Resistance for Compression Loading

a) Cohesive soil

qmax = Nc* x su = kPa

where, Nc* = bearing capacity factor =6.5 at su = 24 kPa8.0 at su = 48 kPa9.0 at su > 25 kPa

su = average undrained shear strength between the base of the pile andan elevation 2B below the base

b) Cohesionless soil

qmax = 57.5 N60 = kPa

where, N60 = average SPT blow count between the base of the pile and an elevation 2B below the base for condition which approximately60 percent of the potential energy of hammer is transferred

2) Side Resistance for Compression Loading

0.0

9

594.0

a) Cohesive soil

fmax = x su

where, = a dimensionless correction coefficient defined as follows: = 0 between the ground surface and a depth of 1.5 m or to the

depth of seasonal moisture change, whichever is deeper = 0 for a distance of B (the diameter of the base) above the base = 0.55 for su / Pa 1.5 (Mpa) = 0.55 - 0.1 ( su / Pa - 1.5 ) for 1.5 su / Pa 2.5 (Mpa)where, Pa =the atmospheric pressure in the units being used

(e.g., 101 kPa in the SI system).

b) Cohesionless soil

fmax = x 'v

where, 'v = vertical effective stress at the middle of layer

= dimensionless correction factor defined as follows:in sands

= 1.5 - 0.245 z0.5 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

in gravelly sands or gravels = 2.0 - 0.15 z0.75 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

where, z = vertical distance from the ground surface to the middle of layer (in meters)

30/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Note: 1) Thickness of layer.

4) Allowable compression capacity

Qa = ( qmax x Ap ) / FSbearing + Qs / FSfriction = kN

1446.0

807.0

sum0.0 0.0 0.0 0.02 0 0.0 0.00 0.0 0.00

0.02 0 0.0 0.00 0.0 0.00 0.0 0.0 0.00.0 0.0 0.0 0.02 0 0.0 0.00 0.0 0.00

205.32 15 66.0 0.50 52.6 0.55 36.3 3.0 5.733.9 2.0 3.8 127.72 14 61.6 0.54 44.7 0.55

155.12 17 74.8 0.74 38.3 0.55 41.1 2.0 3.826.6 3.0 5.7 150.52 11 48.4 0.55 30.3 0.55

273.72 30 132.0 0.85 22.3 0.55 72.6 2.0 3.821.8 3.0 5.7 123.22 9 39.6 0.59 14.4 0.55

410.51 30 132.0 1.20 4.8 0.55 72.6 3.0 5.7(blow) (kPa) (kPa) (m) (m2)

As Qs(kN)

LayerNo.

N60 su v'(kPa)

fmax Thick.1)

31/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.4.3 Allowable Tension Capacity (Reese and O'Neill, 1999)

1) Base resistance for uplift loading

qmax (uplift)1) = 0

Note: 1) qmax should be taken as zero for uplift loading unless experience or load testing atthe construction site can show that suction between the bottom of the drilled shaftand the soil can be predicted reliably or the drilled shaft has a bell.

2) Side resistance for uplift loading

fmax (uplift) = x fmax (compression)

where, = for Cohesive soil = for Cohesionless soil

Cohesive 127.7 1.00 127.7

Cohesive 150.5 1.00 150.5Cohesive 155.1 1.00 155.1

Cohesive 123.2 1.00 123.2Cohesive 273.7 1.00 273.7

(kN)Cohesive 410.5 1.00 410.5

1.000.75

Soil typeQs Ts

(kN)

sum =

3) Allowable tension capacity

Ta = ( Tp + Ts ) / FSfriction = kN723.0

0 0.0 0.00 0.01446.0

0 0.0 0.00 0.00 0.0 0.00 0.0

Cohesive 205.3 1.00 205.3

32/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.4.4 Allowable Lateral Load Capacity (Broms' Method)

1) Coefficient of horizontal subgrade reaction

a) General soil type1) :

Note: 1) Determine the general soil type within the critical depth below the grond FHWA-HI-97-013surface (about 4 or 5 pile diameters). Chapter 9

b) Average soil parameter with the critical depth

su = kPa for Cohesive soil

= deg for Cohesionless soil

where, = Internal friction angle correleted by Ozaki's equation1)

Note: 1) = ( 20 N )0.5 + 15

c) Coefficient of horizontal subgrade reaction, Kh

Kh = n1 x n2 x 80 x qu / b = kN/m3 for Cohesive soil

where, qu = Unconfined compressive strength = kPa

132

0.0

######

264

Cohesive

b = Width or diameter of pile = m

n1 = Empirical coefficients dependent on qu =n1 = 0.32 for less than 48 kPan1 = 0.36 for 48 to 191 kPan1 = 0.40 for more than 191 kPa

n2 = Empirical coefficient dependent on pile material =n2 = 1.00 for steeln2 = 1.15 for concreten2 = 1.30 for wood

Kh = kN/m3 for Cohesionless soil

where, above ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

below ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

542910857

1.15

0.0

19008143

17644

1086

0.6

0.4

33/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2) Pile parameters

a) Modulus of elasticity, E = Mpa

b) Moment of inertia, I = m4

c) Section modulus, S = m3

d) Embedded pile length D = m

e) Diameter or width, b = m

f) Ultimate compression strength for concrete, f'c = Mpa

g) Eccentricity of applied load for free-headed piles, ec =

h) Resisting moment of pile for concrete piles, My = fc' S kN-m

3) Dimensionless length factor

a) Stiffness factor

h = ( Kh b / 4EI )0.25 = m-1 for Cohesive soil,

0.60

25.0

0.0

530.1

0.35

25000

0.0064

0.0212

18.0

= (Kh / EI)0.20 = m-1 for Cohesionless soil,

b) Length factor

h D = for Cohesive soil,

D = for Cohesionless soil,

4) Determine if the pile is long or short

a) Cohesive soil:

where, h D > 2.25 (long pile)h D < 2.25 (short pile)

b) Cohesionless soil:

where, D > 4.0 (long pile) D < 2.0 (short pile)2.0 < D < 4.0 (intermediate pile)

Soil type =Pile type =

6.33

0.00

long pile

short pile

Cohesivelong pile

0.00

34/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

5) Soil parameters

cu = kPa

where, cu = cohesion for cohesive soil

6) Ultimate lateral load (Cohesionless, long pile)

My/cub3 =

ec/b =Qu/cub

2 = from the below chartQu = kN

132

18.60

17.0807.8

7) Allowable lateral load capacity

Hu = kN

Ha = Hu / FSlateral = kN

807.8

403.9

35/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.4.5 PILE SETTLEMENT

Elastic Settlement of Pile

se(1) = (Qwp + Qws) x L / (Ap x Ep)

where, Qwp = load carried at the pile point under working load conditionQws = load carried by frictional resistance under working load conditionAp = area of cross section of pileL = length of pile Ep = modulus of elasticity of the pile material = coefficient which will depend on the nature of the distribution of the unit

friction resistance along the pile shaftconservatively, 0.5

Settlement of Pile Caused by the Load at the Pile Tip (Vesic, 1977)

18.0 25000 0.5 1.44Design-N 325.0 482.0 0.28

se(1)(Mpa) (mm)

BoreholeQwp Qws Ap L Ep(kN) (kN) (m2) (m)

se(2) = (Qwp x Cp) / (D x qp)

where, qp = ultimate point resistance of the pileCp = an empirical coefficient

Settlement of Pile Caused by the Load Transmitted along the Pile Shaft (Vesic, 1977)

se(3) = (QwS x CS) / (L x qp)

where, Cs = an empirical constant = [ 0.93 + 0.16 (L / D)0.5 ] Cp

Type of soil Driven piles Bored pilesSand (dense to loose) 0.02 - 0.04 0.09 - 0.18

Clay (Stiff to Soft) 0.02 - 0.03 0.03 - 0.06Silt (dense to loose) 0.03 - 0.05 0.09 - 0.12

BoreholeD Qwp qp Cp

se(2)(mm) (kN) (kN/m2) (mm)

Design-N 600 325.0 1663.2 0.04 13.03

BoreholeL Qws qp Cs

se(3)(m) (kN) (kN/m2) (mm)

Design-N 18.0 482.0 1663.2 0.07 1.16

36/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Total Settlement of Pile

se = se(1) + se(2) + se(3)

where, se(1) = elastic settlement of pilese(2) = settlement of pile caused by the load at the pile tipse(3) = settlement of pile caused by the load transmitted along the pile shaft

Note: 1) se(allowable) = mmEurocode 7: Geotechnical design, Annex H, For normal structures with isolated foundations, total settlements up to 50mm areoften acceptable.

Boreholese(1) se(2) se(3) se

Design-N 1.44 13.03 1.16 15.63 O.K

50.0

Check1)(mm) (mm) (mm) (mm)

37/124

No. C A L C U L A T I O N REF.

2.5 BH-06

2.5.1 Subsoil Conditions

m G.W.T (m) =

~

Note: 1) "Cohesive" = clay or plastic sily, "Cohesionless" = sand, gravel or non-plastic silt

2) For cohesionless soil, we couldn't carry out unit weight tests because sampling of

-20.0 Cohesive 92.4

21 92.4-18.0 -20.0 -19.0 Cohesive 13.0 21-15.0 -18.0 -16.5 Cohesive 13.0 17 17 74.8

92.4-13.0 -15.0 -14.0 Cohesive 13.0 16 16 70.4

18 79.2-11.0 -13.0 -12.0 Cohesive 13.0 21 21-8.0 -11.0 -9.5 Cohesive 13.0 18-6.0 -8.0 -7.0 Cohesive 13.0 14 14 61.6

17.6-3.0 -6.0 -4.5 Cohesive 13.0 13 13 57.2

(blow) (blow) (kPa)0.0 -3.0 -1.5 Cohesive 13.0 4 4

Depth of layer (m)Soil type1)

2) N3) N604) su

5)

from to center (kN/m3)

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

BH-06 Pile Length = 20.0 0.0

cohesionless soil is very difficult. Therefore, we use typical soil properties in a naturalstate and conservartively select soil type.

- Type of soil = Loose angular-grained silty sand - Natural moisture content in a saturated sta = 25 % - Dry unit weight, d = 12 kN/m3

3) SPT N-value obtained from the field test Attachment-2

4) Corrected for hammer energy without overburden pressure correctionN60 = ( ER / 60 ) x N where, ER = SPT energy ratio = 60 %

5) Cohesion of so(take minimum value from following two equations)K N where K = 4 kN/m2 (Stroud, 1974)29 N0.72( Hara et al, 1971)

38/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.5.2 Allowable Compression Capacity (Reese and O'Neill, 1999)

1) Base Resistance for Compression Loading

a) Cohesive soil

qmax = Nc* x su = kPa

where, Nc* = bearing capacity factor =6.5 at su = 24 kPa8.0 at su = 48 kPa9.0 at su > 25 kPa

su = average undrained shear strength between the base of the pile andan elevation 2B below the base

b) Cohesionless soil

qmax = 57.5 N60 = kPa

where, N60 = average SPT blow count between the base of the pile and an elevation 2B below the base for condition which approximately60 percent of the potential energy of hammer is transferred

2) Side Resistance for Compression Loading

0.0

9

831.6

a) Cohesive soil

fmax = x su

where, = a dimensionless correction coefficient defined as follows: = 0 between the ground surface and a depth of 1.5 m or to the

depth of seasonal moisture change, whichever is deeper = 0 for a distance of B (the diameter of the base) above the base = 0.55 for su / Pa 1.5 (Mpa) = 0.55 - 0.1 ( su / Pa - 1.5 ) for 1.5 su / Pa 2.5 (Mpa)where, Pa =the atmospheric pressure in the units being used

(e.g., 101 kPa in the SI system).

b) Cohesionless soil

fmax = x 'v

where, 'v = vertical effective stress at the middle of layer

= dimensionless correction factor defined as follows:in sands

= 1.5 - 0.245 z0.5 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

in gravelly sands or gravels = 2.0 - 0.15 z0.75 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

where, z = vertical distance from the ground surface to the middle of layer (in meters)

39/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Note: 1) Thickness of layer.

4) Allowable compression capacity

Qa = ( qmax x Ap ) / FSbearing + Qs / FSfriction = kN

1368.5

801.8

sum0.0 0.0 0.0 0.02 0 0.0 0.00 0.0 0.00

0.02 0 0.0 0.00 0.0 0.00 0.0 0.0 0.050.8 2.0 3.8 191.62 21 92.4 0.60 60.6 0.55

232.62 17 74.8 0.57 52.6 0.55 41.1 3.0 5.738.7 2.0 3.8 146.02 16 70.4 0.62 44.7 0.55

191.62 21 92.4 0.91 38.3 0.55 50.8 2.0 3.843.6 3.0 5.7 246.32 18 79.2 0.89 30.3 0.55

127.72 14 61.6 0.80 22.3 0.55 33.9 2.0 3.831.5 3.0 5.7 177.92 13 57.2 0.85 14.4 0.55

54.71 4 17.6 0.32 4.8 0.55 9.7 3.0 5.7(blow) (kPa) (kPa) (m) (m2)

As Qs(kN)

LayerNo.

N60 su v'(kPa)

fmax Thick.1)

40/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.5.3 Allowable Tension Capacity (Reese and O'Neill, 1999)

1) Base resistance for uplift loading

qmax (uplift)1) = 0

Note: 1) qmax should be taken as zero for uplift loading unless experience or load testing atthe construction site can show that suction between the bottom of the drilled shaftand the soil can be predicted reliably or the drilled shaft has a bell.

2) Side resistance for uplift loading

fmax (uplift) = x fmax (compression)

where, = for Cohesive soil = for Cohesionless soil

Cohesive 146.0 1.00 146.0

Cohesive 246.3 1.00 246.3Cohesive 191.6 1.00 191.6

Cohesive 177.9 1.00 177.9Cohesive 127.7 1.00 127.7

(kN)Cohesive 54.7 1.00 54.7

1.000.75

Soil typeQs Ts

(kN)

sum =

3) Allowable tension capacity

Ta = ( Tp + Ts ) / FSfriction = kN684.2

0 0.0 0.00 0.01368.5

Cohesive 191.6 1.00 191.60 0.0 0.00 0.0

Cohesive 232.6 1.00 232.6

41/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.5.4 Allowable Lateral Load Capacity (Broms' Method)

1) Coefficient of horizontal subgrade reaction

a) General soil type1) :

Note: 1) Determine the general soil type within the critical depth below the grond FHWA-HI-97-013surface (about 4 or 5 pile diameters). Chapter 9

b) Average soil parameter with the critical depth

su = kPa for Cohesive soil

= deg for Cohesionless soil

where, = Internal friction angle correleted by Ozaki's equation1)

Note: 1) = ( 20 N )0.5 + 15

c) Coefficient of horizontal subgrade reaction, Kh

Kh = n1 x n2 x 80 x qu / b = kN/m3 for Cohesive soil

where, qu = Unconfined compressive strength = kPa

17.6

0.0

1727.1

35.2

Cohesive

b = Width or diameter of pile = m

n1 = Empirical coefficients dependent on qu =n1 = 0.32 for less than 48 kPan1 = 0.36 for 48 to 191 kPan1 = 0.40 for more than 191 kPa

n2 = Empirical coefficient dependent on pile material =n2 = 1.00 for steeln2 = 1.15 for concreten2 = 1.30 for wood

Kh = kN/m3 for Cohesionless soil

where, above ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

below ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

542910857

1.15

0.0

19008143

17644

1086

0.6

0.32

42/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2) Pile parameters

a) Modulus of elasticity, E = Mpa

b) Moment of inertia, I = m4

c) Section modulus, S = m3

d) Embedded pile length D = m

e) Diameter or width, b = m

f) Ultimate compression strength for concrete, f'c = Mpa

g) Eccentricity of applied load for free-headed piles, ec =

h) Resisting moment of pile for concrete piles, My = fc' S kN-m

3) Dimensionless length factor

a) Stiffness factor

h = ( Kh b / 4EI )0.25 = m-1 for Cohesive soil,

0.60

25.0

0.0

530.1

0.20

25000

0.0064

0.0212

20.0

= (Kh / EI)0.20 = m-1 for Cohesionless soil,

b) Length factor

h D = for Cohesive soil,

D = for Cohesionless soil,

4) Determine if the pile is long or short

a) Cohesive soil:

where, h D > 2.25 (long pile)h D < 2.25 (short pile)

b) Cohesionless soil:

where, D > 4.0 (long pile) D < 2.0 (short pile)2.0 < D < 4.0 (intermediate pile)

Soil type =Pile type =

4.02

0.00

long pile

short pile

Cohesivelong pile

0.00

43/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

5) Soil parameters

cu = kPa

where, cu = cohesion for cohesive soil

6) Ultimate lateral load (Cohesionless, long pile)

My/cub3 =

ec/b =Qu/cub

2 = from the below chartQu = kN

58.0367.5

17.6

139.50

7) Allowable lateral load capacity

Hu = kN

Ha = Hu / FSlateral = kN

367.5

183.7

44/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.5.5 PILE SETTLEMENT

Elastic Settlement of Pile

se(1) = (Qwp + Qws) x L / (Ap x Ep)

where, Qwp = load carried at the pile point under working load conditionQws = load carried by frictional resistance under working load conditionAp = area of cross section of pileL = length of pile Ep = modulus of elasticity of the pile material = coefficient which will depend on the nature of the distribution of the unit

friction resistance along the pile shaftconservatively, 0.5

Settlement of Pile Caused by the Load at the Pile Tip (Vesic, 1977)

0.5 1.62Design-N 345.6 456.2 0.28 20.0 25000

se(1)(kN) (kN) (m2) (m) (Mpa) (mm)

BoreholeQwp Qws Ap L Ep

se(2) = (Qwp x Cp) / (D x qp)

where, qp = ultimate point resistance of the pileCp = an empirical coefficient

Settlement of Pile Caused by the Load Transmitted along the Pile Shaft (Vesic, 1977)

se(3) = (QwS x CS) / (L x qp)

where, Cs = an empirical constant = [ 0.93 + 0.16 (L / D)0.5 ] Cp

(kN) (kN/m2) (mm)Design-N 20.0 456.2 1663.2 0.07 1.02

BoreholeL Qws qp Cs

se(3)(m)

Design-N 600 345.6 1663.2 0.04 13.85(mm) (kN) (kN/m2) (mm)

BoreholeD Qwp qp Cp

se(2)

Clay (Stiff to Soft) 0.02 - 0.03 0.03 - 0.06Silt (dense to loose) 0.03 - 0.05 0.09 - 0.12

Type of soil Driven piles Bored pilesSand (dense to loose) 0.02 - 0.04 0.09 - 0.18

45/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Total Settlement of Pile

se = se(1) + se(2) + se(3)

where, se(1) = elastic settlement of pilese(2) = settlement of pile caused by the load at the pile tipse(3) = settlement of pile caused by the load transmitted along the pile shaft

Note: 1) se(allowable) = mmEurocode 7: Geotechnical design, Annex H, For normal structures with isolated foundations, total settlements up to 50mm areoften acceptable.

O.K

50.0

(mm) (mm) (mm) (mm)Design-N 1.62 13.85 1.02 16.49

Boreholese(1) se(2) se(3) se Check1)

46/124

No. C A L C U L A T I O N REF.

2.6 BH-08

2.6.1 Subsoil Conditions

m G.W.T (m) =

~

Note: 1) "Cohesive" = clay or plastic sily, "Cohesionless" = sand, gravel or non-plastic silt

2) For cohesionless soil, we couldn't carry out unit weight tests because sampling of

-20.0 Cohesive 70.4

16 70.4-18.0 -20.0 -19.0 Cohesive 13.0 16-15.0 -18.0 -16.5 Cohesive 13.0 16 16 70.4

92.4-13.0 -15.0 -14.0 Cohesive 13.0 17 17 74.8

15 66-11.0 -13.0 -12.0 Cohesive 13.0 21 21-8.0 -11.0 -9.5 Cohesive 13.0 15-6.0 -8.0 -7.0 Cohesive 13.0 15 15 66

66-3.0 -6.0 -4.5 Cohesive 13.0 12 12 52.8

(blow) (blow) (kPa)0.0 -3.0 -1.5 Cohesive 13.0 15 15

Depth of layer (m)Soil type1)

2) N3) N604) su

5)

from to center (kN/m3)

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

BH-08 Pile Length = 20.0 0.0

cohesionless soil is very difficult. Therefore, we use typical soil properties in a naturalstate and conservartively select soil type.

- Type of soil = Loose angular-grained silty sand - Natural moisture content in a saturated sta = 25 % - Dry unit weight, d = 12 kN/m3

3) SPT N-value obtained from the field test Attachment-2

4) Corrected for hammer energy without overburden pressure correctionN60 = ( ER / 60 ) x N where, ER = SPT energy ratio = 60 %

5) Cohesion of so(take minimum value from following two equations)K N where K = 4 kN/m2 (Stroud, 1974)29 N0.72( Hara et al, 1971)

47/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.6.2 Allowable Compression Capacity (Reese and O'Neill, 1999)

1) Base Resistance for Compression Loading

a) Cohesive soil

qmax = Nc* x su = kPa

where, Nc* = bearing capacity factor =6.5 at su = 24 kPa8.0 at su = 48 kPa9.0 at su > 25 kPa

su = average undrained shear strength between the base of the pile andan elevation 2B below the base

b) Cohesionless soil

qmax = 57.5 N60 = kPa

where, N60 = average SPT blow count between the base of the pile and an elevation 2B below the base for condition which approximately60 percent of the potential energy of hammer is transferred

2) Side Resistance for Compression Loading

0.0

9

633.6

a) Cohesive soil

fmax = x su

where, = a dimensionless correction coefficient defined as follows: = 0 between the ground surface and a depth of 1.5 m or to the

depth of seasonal moisture change, whichever is deeper = 0 for a distance of B (the diameter of the base) above the base = 0.55 for su / Pa 1.5 (Mpa) = 0.55 - 0.1 ( su / Pa - 1.5 ) for 1.5 su / Pa 2.5 (Mpa)where, Pa =the atmospheric pressure in the units being used

(e.g., 101 kPa in the SI system).

b) Cohesionless soil

fmax = x 'v

where, 'v = vertical effective stress at the middle of layer

= dimensionless correction factor defined as follows:in sands

= 1.5 - 0.245 z0.5 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

in gravelly sands or gravels = 2.0 - 0.15 z0.75 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

where, z = vertical distance from the ground surface to the middle of layer (in meters)

48/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Note: 1) Thickness of layer.

4) Allowable compression capacity

Qa = ( qmax x Ap ) / FSbearing + Qs / FSfriction = kN

1423.2

801.2

sum0.0 0.0 0.0 0.02 0 0.0 0.00 0.0 0.00

0.02 0 0.0 0.00 0.0 0.00 0.0 0.0 0.038.7 2.0 3.8 146.02 16 70.4 0.46 60.6 0.55

219.02 16 70.4 0.54 52.6 0.55 38.7 3.0 5.741.1 2.0 3.8 155.12 17 74.8 0.66 44.7 0.55

191.62 21 92.4 0.91 38.3 0.55 50.8 2.0 3.836.3 3.0 5.7 205.32 15 66.0 0.74 30.3 0.55

136.82 15 66.0 0.85 22.3 0.55 36.3 2.0 3.829.0 3.0 5.7 164.22 12 52.8 0.78 14.4 0.55

205.31 15 66.0 1.20 4.8 0.55 36.3 3.0 5.7(blow) (kPa) (kPa) (m) (m2)

As Qs(kN)

LayerNo.

N60 su v'(kPa)

fmax Thick.1)

49/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.6.3 Allowable Tension Capacity (Reese and O'Neill, 1999)

1) Base resistance for uplift loading

qmax (uplift)1) = 0

Note: 1) qmax should be taken as zero for uplift loading unless experience or load testing atthe construction site can show that suction between the bottom of the drilled shaftand the soil can be predicted reliably or the drilled shaft has a bell.

2) Side resistance for uplift loading

fmax (uplift) = x fmax (compression)

where, = for Cohesive soil = for Cohesionless soil

Cohesive 155.1 1.00 155.1

Cohesive 205.3 1.00 205.3Cohesive 191.6 1.00 191.6

Cohesive 164.2 1.00 164.2Cohesive 136.8 1.00 136.8

(kN)Cohesive 205.3 1.00 205.3

1.000.75

Soil typeQs Ts

(kN)

sum =

3) Allowable tension capacity

Ta = ( Tp + Ts ) / FSfriction = kN711.6

0 0.0 0.00 0.01423.2

Cohesive 146.0 1.00 146.00 0.0 0.00 0.0

Cohesive 219.0 1.00 219.0

50/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.6.4 Allowable Lateral Load Capacity (Broms' Method)

1) Coefficient of horizontal subgrade reaction

a) General soil type1) :

Note: 1) Determine the general soil type within the critical depth below the grond FHWA-HI-97-013surface (about 4 or 5 pile diameters). Chapter 9

b) Average soil parameter with the critical depth

su = kPa for Cohesive soil

= deg for Cohesionless soil

where, = Internal friction angle correleted by Ozaki's equation1)

Note: 1) = ( 20 N )0.5 + 15

c) Coefficient of horizontal subgrade reaction, Kh

Kh = n1 x n2 x 80 x qu / b = kN/m3 for Cohesive soil

where, qu = Unconfined compressive strength = kPa

66

0.0

7286.4

132

Cohesive

b = Width or diameter of pile = m

n1 = Empirical coefficients dependent on qu =n1 = 0.32 for less than 48 kPan1 = 0.36 for 48 to 191 kPan1 = 0.40 for more than 191 kPa

n2 = Empirical coefficient dependent on pile material =n2 = 1.00 for steeln2 = 1.15 for concreten2 = 1.30 for wood

Kh = kN/m3 for Cohesionless soil

where, above ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

below ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

542910857

1.15

0.0

19008143

17644

1086

0.6

0.36

51/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2) Pile parameters

a) Modulus of elasticity, E = Mpa

b) Moment of inertia, I = m4

c) Section modulus, S = m3

d) Embedded pile length D = m

e) Diameter or width, b = m

f) Ultimate compression strength for concrete, f'c = Mpa

g) Eccentricity of applied load for free-headed piles, ec =

h) Resisting moment of pile for concrete piles, My = fc' S kN-m

3) Dimensionless length factor

a) Stiffness factor

h = ( Kh b / 4EI )0.25 = m-1 for Cohesive soil,

0.60

25.0

0.0

530.1

0.29

25000

0.0064

0.0212

20.0

= (Kh / EI)0.20 = m-1 for Cohesionless soil,

b) Length factor

h D = for Cohesive soil,

D = for Cohesionless soil,

4) Determine if the pile is long or short

a) Cohesive soil:

where, h D > 2.25 (long pile)h D < 2.25 (short pile)

b) Cohesionless soil:

where, D > 4.0 (long pile) D < 2.0 (short pile)2.0 < D < 4.0 (intermediate pile)

Soil type =Pile type =

5.76

0.00

long pile

short pile

Cohesivelong pile

0.00

52/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

5) Soil parameters

cu = kPa

where, cu = cohesion for cohesive soil

6) Ultimate lateral load (Cohesionless, long pile)

My/cub3 =

ec/b =Qu/cub

2 = from the below chartQu = kN

25.0594.0

66

37.20

7) Allowable lateral load capacity

Hu = kN

Ha = Hu / FSlateral = kN

594.0

297.0

53/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.6.4 PILE SETTLEMENT

Elastic Settlement of Pile

se(1) = (Qwp + Qws) x L / (Ap x Ep)

where, Qwp = load carried at the pile point under working load conditionQws = load carried by frictional resistance under working load conditionAp = area of cross section of pileL = length of pile Ep = modulus of elasticity of the pile material = coefficient which will depend on the nature of the distribution of the unit

friction resistance along the pile shaftconservatively, 0.5

Settlement of Pile Caused by the Load at the Pile Tip (Vesic, 1977)

0.5 1.60Design-N 326.8 474.4 0.28 20.0 25000

se(1)(kN) (kN) (m2) (m) (Mpa) (mm)

BoreholeQwp Qws Ap L Ep

se(2) = (Qwp x Cp) / (D x qp)

where, qp = ultimate point resistance of the pileCp = an empirical coefficient

Settlement of Pile Caused by the Load Transmitted along the Pile Shaft (Vesic, 1977)

se(3) = (QwS x CS) / (L x qp)

where, Cs = an empirical constant = [ 0.93 + 0.16 (L / D)0.5 ] Cp

(kN) (kN/m2) (mm)Design-N 20.0 474.4 1663.2 0.07 1.06

BoreholeL Qws qp Cs

se(3)(m)

Design-N 600 326.8 1663.2 0.04 13.10(mm) (kN) (kN/m2) (mm)

BoreholeD Qwp qp Cp

se(2)

Clay (Stiff to Soft) 0.02 - 0.03 0.03 - 0.06Silt (dense to loose) 0.03 - 0.05 0.09 - 0.12

Type of soil Driven piles Bored pilesSand (dense to loose) 0.02 - 0.04 0.09 - 0.18

54/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Total Settlement of Pile

se = se(1) + se(2) + se(3)

where, se(1) = elastic settlement of pilese(2) = settlement of pile caused by the load at the pile tipse(3) = settlement of pile caused by the load transmitted along the pile shaft

Note: 1) se(allowable) = mmEurocode 7: Geotechnical design, Annex H, For normal structures with isolated foundations, total settlements up to 50mm areoften acceptable.

O.K

50.0

(mm) (mm) (mm) (mm)Design-N 1.60 13.10 1.06 15.75

Boreholese(1) se(2) se(3) se Check1)

55/124

No. C A L C U L A T I O N REF.

2.7 BH-09

2.7.1 Subsoil Conditions

m G.W.T (m) =

~

Note: 1) "Cohesive" = clay or plastic sily, "Cohesionless" = sand, gravel or non-plastic silt

2) For cohesionless soil, we couldn't carry out unit weight tests because sampling of

-18.0 Cohesive 92.4

-15.0 -18.0 -16.5 Cohesive 13.0 21 21 92.4

74.8-13.0 -15.0 -14.0 Cohesive 13.0 20 20 88

17 74.8-11.0 -13.0 -12.0 Cohesive 13.0 17 17-8.0 -11.0 -9.5 Cohesive 13.0 17-6.0 -8.0 -7.0 Cohesive 13.0 19 19 83.6

74.8-3.0 -6.0 -4.5 Cohesive 13.0 8 8 35.2

(blow) (blow) (kPa)0.0 -3.0 -1.5 Cohesive 13.0 17 17

Depth of layer (m)Soil type1)

2) N3) N604) su

5)

from to center (kN/m3)

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

BH-09 Pile Length = 18.0 0.0

cohesionless soil is very difficult. Therefore, we use typical soil properties in a naturalstate and conservartively select soil type.

- Type of soil = Loose angular-grained silty sand - Natural moisture content in a saturated sta = 25 % - Dry unit weight, d = 12 kN/m3

3) SPT N-value obtained from the field test Attachment-2

4) Corrected for hammer energy without overburden pressure correctionN60 = ( ER / 60 ) x N where, ER = SPT energy ratio = 60 %

5) Cohesion of so(take minimum value from following two equations)K N where K = 4 kN/m2 (Stroud, 1974)29 N0.72( Hara et al, 1971)

56/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.7.2 Allowable Compression Capacity (Reese and O'Neill, 1999)

1) Base Resistance for Compression Loading

a) Cohesive soil

qmax = Nc* x su = kPa

where, Nc* = bearing capacity factor =6.5 at su = 24 kPa8.0 at su = 48 kPa9.0 at su > 25 kPa

su = average undrained shear strength between the base of the pile andan elevation 2B below the base

b) Cohesionless soil

qmax = 57.5 N60 = kPa

where, N60 = average SPT blow count between the base of the pile and an elevation 2B below the base for condition which approximately60 percent of the potential energy of hammer is transferred

2) Side Resistance for Compression Loading

0.0

9

831.6

a) Cohesive soil

fmax = x su

where, = a dimensionless correction coefficient defined as follows: = 0 between the ground surface and a depth of 1.5 m or to the

depth of seasonal moisture change, whichever is deeper = 0 for a distance of B (the diameter of the base) above the base = 0.55 for su / Pa 1.5 (Mpa) = 0.55 - 0.1 ( su / Pa - 1.5 ) for 1.5 su / Pa 2.5 (Mpa)where, Pa =the atmospheric pressure in the units being used

(e.g., 101 kPa in the SI system).

b) Cohesionless soil

fmax = x 'v

where, 'v = vertical effective stress at the middle of layer

= dimensionless correction factor defined as follows:in sands

= 1.5 - 0.245 z0.5 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

in gravelly sands or gravels = 2.0 - 0.15 z0.75 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

where, z = vertical distance from the ground surface to the middle of layer (in meters)

57/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Note: 1) Thickness of layer.

4) Allowable compression capacity

Qa = ( qmax x Ap ) / FSbearing + Qs / FSfriction = kN

1373.0

804.1

sum0.0 0.0 0.0 0.02 0 0.0 0.00 0.0 0.00

0.02 0 0.0 0.00 0.0 0.00 0.0 0.0 0.00.0 0.0 0.0 0.02 0 0.0 0.00 0.0 0.00

287.42 21 92.4 0.71 52.6 0.55 50.8 3.0 5.748.4 2.0 3.8 182.52 20 88.0 0.78 44.7 0.55

155.12 17 74.8 0.74 38.3 0.55 41.1 2.0 3.841.1 3.0 5.7 232.62 17 74.8 0.84 30.3 0.55

173.32 19 83.6 1.08 22.3 0.55 46.0 2.0 3.819.4 3.0 5.7 109.52 8 35.2 0.52 14.4 0.55

232.61 17 74.8 1.36 4.8 0.55 41.1 3.0 5.7(blow) (kPa) (kPa) (m) (m2)

As Qs(kN)

LayerNo.

N60 su v'(kPa)

fmax Thick.1)

58/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.7.3 Allowable Tension Capacity (Reese and O'Neill, 1999)

1) Base resistance for uplift loading

qmax (uplift)1) = 0

Note: 1) qmax should be taken as zero for uplift loading unless experience or load testing atthe construction site can show that suction between the bottom of the drilled shaftand the soil can be predicted reliably or the drilled shaft has a bell.

2) Side resistance for uplift loading

fmax (uplift) = x fmax (compression)

where, = for Cohesive soil = for Cohesionless soil

Cohesive 182.5 1.00 182.5

Cohesive 232.6 1.00 232.6Cohesive 155.1 1.00 155.1

Cohesive 109.5 1.00 109.5Cohesive 173.3 1.00 173.3

(kN)Cohesive 232.6 1.00 232.6

1.000.75

Soil typeQs Ts

(kN)

sum =

3) Allowable tension capacity

Ta = ( Tp + Ts ) / FSfriction = kN686.5

0 0.0 0.00 0.01373.0

0 0.0 0.00 0.00 0.0 0.00 0.0

Cohesive 287.4 1.00 287.4

59/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.7.4 Allowable Lateral Load Capacity (Broms' Method)

1) Coefficient of horizontal subgrade reaction

a) General soil type1) :

Note: 1) Determine the general soil type within the critical depth below the grond FHWA-HI-97-013surface (about 4 or 5 pile diameters). Chapter 9

b) Average soil parameter with the critical depth

su = kPa for Cohesive soil

= deg for Cohesionless soil

where, = Internal friction angle correleted by Ozaki's equation1)

Note: 1) = ( 20 N )0.5 + 15

c) Coefficient of horizontal subgrade reaction, Kh

Kh = n1 x n2 x 80 x qu / b = kN/m3 for Cohesive soil

where, qu = Unconfined compressive strength = kPa

74.8

0.0

8257.9

149.6

Cohesive

b = Width or diameter of pile = m

n1 = Empirical coefficients dependent on qu =n1 = 0.32 for less than 48 kPan1 = 0.36 for 48 to 191 kPan1 = 0.40 for more than 191 kPa

n2 = Empirical coefficient dependent on pile material =n2 = 1.00 for steeln2 = 1.15 for concreten2 = 1.30 for wood

Kh = kN/m3 for Cohesionless soil

where, above ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

below ground waterKh = kN/m3 for loose densityKh = kN/m3 for medium densityKh = kN/m3 for dense density

542910857

1.15

0.0

19008143

17644

1086

0.6

0.36

60/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2) Pile parameters

a) Modulus of elasticity, E = Mpa

b) Moment of inertia, I = m4

c) Section modulus, S = m3

d) Embedded pile length D = m

e) Diameter or width, b = m

f) Ultimate compression strength for concrete, f'c = Mpa

g) Eccentricity of applied load for free-headed piles, ec =

h) Resisting moment of pile for concrete piles, My = fc' S kN-m

3) Dimensionless length factor

a) Stiffness factor

h = ( Kh b / 4EI )0.25 = m-1 for Cohesive soil,

0.60

25.0

0.0

530.1

0.30

25000

0.0064

0.0212

18.0

= (Kh / EI)0.20 = m-1 for Cohesionless soil,

b) Length factor

h D = for Cohesive soil,

D = for Cohesionless soil,

4) Determine if the pile is long or short

a) Cohesive soil:

where, h D > 2.25 (long pile)h D < 2.25 (short pile)

b) Cohesionless soil:

where, D > 4.0 (long pile) D < 2.0 (short pile)2.0 < D < 4.0 (intermediate pile)

Soil type =Pile type =

5.35

0.00

long pile

short pile

Cohesivelong pile

0.00

61/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

5) Soil parameters

cu = kPa

where, cu = cohesion for cohesive soil

6) Ultimate lateral load (Cohesionless, long pile)

My/cub3 =

ec/b =Qu/cub

2 = from the below chartQu = kN

22.0592.4

74.8

32.80

7) Allowable lateral load capacity

Hu = kN

Ha = Hu / FSlateral = kN

592.4

296.2

62/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.7.5 PILE SETTLEMENT

Elastic Settlement of Pile

se(1) = (Qwp + Qws) x L / (Ap x Ep)

where, Qwp = load carried at the pile point under working load conditionQws = load carried by frictional resistance under working load conditionAp = area of cross section of pileL = length of pile Ep = modulus of elasticity of the pile material = coefficient which will depend on the nature of the distribution of the unit

friction resistance along the pile shaftconservatively, 0.5

Settlement of Pile Caused by the Load at the Pile Tip (Vesic, 1977)

0.5 1.46Design-N 346.4 457.7 0.28 18.0 25000

se(1)(kN) (kN) (m2) (m) (Mpa) (mm)

BoreholeQwp Qws Ap L Ep

se(2) = (Qwp x Cp) / (D x qp)

where, qp = ultimate point resistance of the pileCp = an empirical coefficient

Settlement of Pile Caused by the Load Transmitted along the Pile Shaft (Vesic, 1977)

se(3) = (QwS x CS) / (L x qp)

where, Cs = an empirical constant = [ 0.93 + 0.16 (L / D)0.5 ] Cp

(kN) (kN/m2) (mm)Design-N 18.0 457.7 1663.2 0.07 1.10

BoreholeL Qws qp Cs

se(3)(m)

Design-N 600 346.4 1663.2 0.04 13.89(mm) (kN) (kN/m2) (mm)

BoreholeD Qwp qp Cp

se(2)

Clay (Stiff to Soft) 0.02 - 0.03 0.03 - 0.06Silt (dense to loose) 0.03 - 0.05 0.09 - 0.12

Type of soil Driven piles Bored pilesSand (dense to loose) 0.02 - 0.04 0.09 - 0.18

63/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Total Settlement of Pile

se = se(1) + se(2) + se(3)

where, se(1) = elastic settlement of pilese(2) = settlement of pile caused by the load at the pile tipse(3) = settlement of pile caused by the load transmitted along the pile shaft

Note: 1) se(allowable) = mmEurocode 7: Geotechnical design, Annex H, For normal structures with isolated foundations, total settlements up to 50mm areoften acceptable.

O.K

50.0

(mm) (mm) (mm) (mm)Design-N 1.46 13.89 1.10 16.45

Boreholese(1) se(2) se(3) se Check1)

64/124

No. C A L C U L A T I O N REF.

2.8 BH-10

2.8.1 Subsoil Conditions

m G.W.T (m) =

~

Note: 1) "Cohesive" = clay or plastic sily, "Cohesionless" = sand, gravel or non-plastic silt

2) For cohesionless soil, we couldn't carry out unit weight tests because sampling of

-18.0 Cohesive 70.4

-15.0 -18.0 -16.5 Cohesive 13.0 16 16 70.4

105.6-13.0 -15.0 -14.0 Cohesive 13.0 18 18 79.2

16 70.4-11.0 -13.0 -12.0 Cohesive 13.0 24 24-8.0 -11.0 -9.5 Cohesive 13.0 16-6.0 -8.0 -7.0 Cohesive 13.0 11 11 48.4

101.2-3.0 -6.0 -4.5 Cohesive 13.0 14 14 61.6

(blow) (blow) (kPa)0.0 -3.0 -1.5 Cohesive 13.0 23 23

Depth of layer (m)Soil type1)

2) N3) N604) su

5)

from to center (kN/m3)

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

BH-10 Pile Length = 18.0 0.0

cohesionless soil is very difficult. Therefore, we use typical soil properties in a naturalstate and conservartively select soil type.

- Type of soil = Loose angular-grained silty sand - Natural moisture content in a saturated sta = 25 % - Dry unit weight, d = 12 kN/m3

3) SPT N-value obtained from the field test Attachment-2

4) Corrected for hammer energy without overburden pressure correctionN60 = ( ER / 60 ) x N where, ER = SPT energy ratio = 60 %

5) Cohesion of so(take minimum value from following two equations)K N where K = 4 kN/m2 (Stroud, 1974)29 N0.72( Hara et al, 1971)

65/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.8.2 Allowable Compression Capacity (Reese and O'Neill, 1999)

1) Base Resistance for Compression Loading

a) Cohesive soil

qmax = Nc* x su = kPa

where, Nc* = bearing capacity factor =6.5 at su = 24 kPa8.0 at su = 48 kPa9.0 at su > 25 kPa

su = average undrained shear strength between the base of the pile andan elevation 2B below the base

b) Cohesionless soil

qmax = 57.5 N60 = kPa

where, N60 = average SPT blow count between the base of the pile and an elevation 2B below the base for condition which approximately60 percent of the potential energy of hammer is transferred

2) Side Resistance for Compression Loading

0.0

9

633.6

a) Cohesive soil

fmax = x su

where, = a dimensionless correction coefficient defined as follows: = 0 between the ground surface and a depth of 1.5 m or to the

depth of seasonal moisture change, whichever is deeper = 0 for a distance of B (the diameter of the base) above the base = 0.55 for su / Pa 1.5 (Mpa) = 0.55 - 0.1 ( su / Pa - 1.5 ) for 1.5 su / Pa 2.5 (Mpa)where, Pa =the atmospheric pressure in the units being used

(e.g., 101 kPa in the SI system).

b) Cohesionless soil

fmax = x 'v

where, 'v = vertical effective stress at the middle of layer

= dimensionless correction factor defined as follows:in sands

= 1.5 - 0.245 z0.5 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

in gravelly sands or gravels = 2.0 - 0.15 z0.75 for N60 15 B / 0.3 m = ( N60 / 15 ) x ( 1.5 - 0.245 z0.5 ) for N60 < 15 B / 0.3 m

where, z = vertical distance from the ground surface to the middle of layer (in meters)

66/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

Note: 1) Thickness of layer.

4) Allowable compression capacity

Qa = ( qmax x Ap ) / FSbearing + Qs / FSfriction = kN

1427.8

803.5

sum0.0 0.0 0.0 0.02 0 0.0 0.00 0.0 0.00

0.02 0 0.0 0.00 0.0 0.00 0.0 0.0 0.00.0 0.0 0.0 0.02 0 0.0 0.00 0.0 0.00

219.02 16 70.4 0.54 52.6 0.55 38.7 3.0 5.743.6 2.0 3.8 164.22 18 79.2 0.70 44.7 0.55

219.02 24 105.6 1.04 38.3 0.55 58.1 2.0 3.838.7 3.0 5.7 219.02 16 70.4 0.79 30.3 0.55

100.42 11 48.4 0.62 22.3 0.55 26.6 2.0 3.833.9 3.0 5.7 191.62 14 61.6 0.91 14.4 0.55

314.71 23 101.2 1.84 4.8 0.55 55.7 3.0 5.7(blow) (kPa) (kPa) (m) (m2)

As Qs(kN)

LayerNo.

N60 su v'(kPa)

fmax Thick.1)

67/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.8.3 Allowable Tension Capacity (Reese and O'Neill, 1999)

1) Base resistance for uplift loading

qmax (uplift)1) = 0

Note: 1) qmax should be taken as zero for uplift loading unless experience or load testing atthe construction site can show that suction between the bottom of the drilled shaftand the soil can be predicted reliably or the drilled shaft has a bell.

2) Side resistance for uplift loading

fmax (uplift) = x fmax (compression)

where, = for Cohesive soil = for Cohesionless soil

Cohesive 164.2 1.00 164.2

Cohesive 219.0 1.00 219.0Cohesive 219.0 1.00 219.0

Cohesive 191.6 1.00 191.6Cohesive 100.4 1.00 100.4

(kN)Cohesive 314.7 1.00 314.7

1.000.75

Soil typeQs Ts

(kN)

sum =

3) Allowable tension capacity

Ta = ( Tp + Ts ) / FSfriction = kN713.9

0 0.0 0.00 0.01427.8

0 0.0 0.00 0.00 0.0 0.00 0.0

Cohesive 219.0 1.00 219.0

68/124

No. C A L C U L A T I O N REF.

OLKARIA IV GEOTHERMAL POWER PLANTREV. A

TITLE : DESIGN CALCULATION - BORED CAST IN-SITU PILE

2.8.4 Allowable Lateral Load Capacity (Broms' Method)

1) Coefficient of horizontal subgrade reaction

a) General soil type1) :

Note: 1) Determine the general soil type within the critical depth below the grond FHWA-HI-97-013surface (about 4 or 5 pile diameters). Chapter 9

b) Average soil parameter with the critical depth

su = kPa for Cohesive soil

= deg for Cohesionless soil

where, = Internal friction angle correleted by Ozaki's equation1)

Note: 1) = ( 20 N )0.5 + 15

c) Coefficient of horizontal subgrade reaction, Kh

Kh = n1 x n2 x 80 x qu / b = kN/m3 for Cohesive soil

where, qu = Unconfined compressive strength = kPa

101.2

0.0

######

202.4

Cohesive

b = Width or diameter of pile = m

n1 = Empirical coefficients dependent on qu =n1 = 0.32 for less than 48 k