pile design - great stuff
DESCRIPTION
Pile DesignTRANSCRIPT
-
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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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)
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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
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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