2. DEEP FOUNDATION – 101
▪ For the layered soil where the upper
parts are too weak / highly
compressible
▪ When the horizontal force acting on
the foundation is remarkable, i.e.
wind, earthquake forces
▪ For expansive soils
▪ To resist uplifting forces (e.g.,
offshore structures)
▪ Avoid the loss of bearing capacity
due to soil erosion
3. DEEP FOUNDATION – 101
▪ For the layered soil where the upper
parts are too weak / highly
compressible
▪ When the horizontal force acting on
the foundation is remarkable, i.e.
wind, earthquake forces
▪ For expansive soils
▪ To resist uplifting forces (e.g.,
offshore structures)
▪ Avoid the loss of bearing capacity
due to soil erosion
4. DEEP FOUNDATION – 101
▪ For the layered soil where the upper
parts are too weak / highly
compressible
▪ When the horizontal force acting on
the foundation is remarkable, i.e.
wind, earthquake forces
▪ For expansive soils
▪ To resist uplifting forces (e.g.,
offshore structures)
▪ Avoid the loss of bearing capacity
due to soil erosion
5. DEEP FOUNDATION – 101
▪ For the layered soil where the upper
parts are too weak / highly
compressible
▪ When the horizontal force acting on
the foundation is remarkable, i.e.
wind, earthquake forces
▪ For expansive soils
▪ To resist uplifting forces (e.g.,
offshore structures)
▪ Avoid the loss of bearing capacity
due to soil erosion
6. DEEP FOUNDATION – 101
▪ For the layered soil where the upper
parts are too weak / highly
compressible
▪ When the horizontal force acting on
the foundation is remarkable, i.e.
wind, earthquake forces
▪ For expansive soils
▪ To resist uplifting forces (e.g.,
offshore structures)
▪ Avoid the loss of bearing capacity
due to soil erosion
7. TYPES OF PILE
A. BASED ON MATERIAL – TIMBER (1)
Steel cap
Steel shoe
Class A -> ∅ = 356 𝑚𝑚
Class B -> ∅ = 305 − 330 𝑚𝑚
Class C -> ∅ = 305 𝑚𝑚
𝑄𝑎𝑙𝑙 = 𝐴𝑝𝑓𝑤
Av. Cross-
section area
Allowable
stress
Max. Length = 20 – 30m
8. TYPES OF PILE
A. BASED ON MATERIAL – PRECAST CONCRETE (2)
Re-bar to resist bending moment and vertical load
Advantages:
• Can be subjected to hard driving force
• Corrosion resistant
• Easily combined with concrete superstructure
Rebar Concrete
Length = 10 – 15m
Max. Load = 0.3 – 3 MN • Developed during transportation
• Due to lateral load
Disadvantages:
• Difficult to achieve proper cutoff
• Difficult to transport
Prestressed Concrete
Length = 10 – 45m, max. 60m
Max. Load = 7.5 – 8.5 MN
Strand is pretensioned with
900 – 1300 MPa
prestressing stress
9. TYPES OF PILE
A. BASED ON MATERIAL – PRECAST CONCRETE (2)
𝑄𝑎𝑙𝑙 = 𝐴𝑝𝑓𝑝 + 𝐴𝑐𝑓𝑐
10. TYPES OF PILE
A. BASED ON MATERIAL – IN-SITU CAST CONCRETE (3)
Usual length: 5 – 15m
Max. length: 30 – 40m
Usual load: 200 – 500kN; max. 800kN
Advantages:
• Relatively cheap
• Allow for inspection prior to production
• Easy to extend
Disadvantages:
• Difficult to splice after hardening
• Thin casings can be damaged during
driving
𝑄𝑎𝑙𝑙 = 𝐴𝑠𝑓𝑠 + 𝐴𝑐𝑓𝑐
11. TYPES OF PILE
A. BASED ON MATERIAL – IN-SITU CAST CONCRETE (3)
Usual length: 5 – 15m
Max. length: 30 – 40m
Usual load: 200 – 500kN; max. 800kN
Advantages:
• Relatively cheap
• Allow for inspection prior to production
• Easy to extend
Disadvantages:
• Difficult to splice after hardening
• Thin casings can be damaged during
driving
𝑄𝑎𝑙𝑙 = 𝐴𝑐𝑓𝑐
15. TYPES OF PILE
A. BASED ON MATERIAL – STEEL (4)
Usual length: 15 – 60m
Usual load: 300 – 1200kN
Advantages:
• Easy to modify (cutoff, extend)
• Can stand high driving force
• Can penetrate hard layers
• High load-carrying capacity
Disadvantages:
• Expensive
• High noise during driving
• Prone to corrosion
• Prone to deflection/cross-section
damage -> H-section
𝑄𝑎𝑙𝑙 = 𝐴𝑆𝑓𝑆
𝒇𝑺 =
𝟏
𝟑
~
𝟏
𝟐
𝒇𝒚
28. POINT LOAD (QP) – MEYERHOFF
pa = atmospheric
pressure = 100 kPa
1. Sand
2. Saturated clay
Note:
Both 𝜙’ and cu are from the bearing
soil, i.e. beneath the tip of the pile
29. POINT LOAD (QP) – VESIC
1. Sand
pa = atmospheric pressure = 100 kPa
2. Saturated clay
32. POINT LOAD (QP) - PILE ON ROCK
Min. 3
To incorporate the size effect of the lab test sample, then
33. EXAMPLE 1
Consider a 20-m-long concrete pile with a cross section of
0.407m x 0.407m fully embedded in sand. For the sand,
given: unit weight, = 18 kN/m3; and soil friction angle =
35o.
Estimate the ultimate point Qp with each of the following:
a. Meyerhof’s method
b. Vesic’s method
c. The method of Coyle and Castello
d. Based on the results of parts a, b, and c, adopt a value
for Qp
34. EXAMPLE 2
Consider a pipe pile (flat driving point)
having an outside diameter of 457 mm. The
embedded length of the pile in layered
saturated clay is 20 m.
The details of the subsoil are given in the
following table.
The groundwater table is located at a depth
of 3 m from the ground surface. Estimate Qp
by using:
• Meyerhof’s method
• Vesic’s method
35. FRICTIONAL RESISTANCE (QS)
1. Sand
“Quite difficult to estimate"
0.5 − 0.8 𝜙’
Mansur & Hunter
(1970)
0.8 𝜙’
Av. Eff. Overburden pressure
Coyle & Castello
(1981)
≈ 15𝐷
36. FRICTIONAL RESISTANCE (QS)
1. Sand – SPT result
High-displacement driven pile
Meyerhoff (1976)
Low-displacement driven pile
Briaud et al. (1985)
2. Sand –
CPT result
𝑄𝑠 = 𝑝 ∆𝐿 𝛼’𝑓𝑐
Electric Sondir
Mechanical Sondir
37. FRICTIONAL RESISTANCE (QS)
2. Clay
𝝀 method - Vijayvergiya and Focht (1972)
𝜎’0 = mean eff. Vertical stress
within the embedment
length
𝑐𝑢= undrained shear strength (𝜙 = 0)
40. EXAMPLE 3
• Calculate the skin resistance (Qs) by (1) the
𝜆 method, (2) the 𝛼 method, and (3) the 𝛽
method.
For the 𝛽 method, use 𝜙’𝑅 = 30∘
for all
clay layers. The top 10 m of clay is
normally consolidated. The bottom clay
layer has an OCR = 2. (Note: diameter of
pile = 457 mm)
• For Qp = 151 kN, estimate the allowable
pile capacity (Qall). Use FS = 4.
43. IMPACT DRIVING
1. Energy-based equation (Engineering News)
Conservation of energy
Steam
hammer
Drop
hammer
Weight of ram
Height of fall for ram
Pile penetration per
hammer blow
For Double Acting Hammer,
Efficiency
Rated energy of hammer
45. WAVE EQUATION
FOR IMPACT DRIVE
The preceded equations were not reliable ->
Empirical only
Only applies to certain type and length of pile
Wave equation approach is introduced
46.
47. VIBRATORY
DRIVING
Horsepower
delivered to pile
Final rate of pile
penetration
Loss
factor
Davison (1970)
For granular soil
Centrifugal
Force
Bias
Weight
Final rate of
pile
penetration Speed
of light
Embedded
length
Length of
pile
Feng & Deschamps (2000)
For granular soil
Total eccentric
rotating mass
Distance centre of
each rotating
mass – centre of
rotation
Angular
frequency
52. SETTLEMENT
OF PILE
load carried at
the pile point
under working
load condition
Skin resistance
under working
load condition
Cross-
section
area
Elastic
Modulus
pile
“Linear Elastic Solution”
𝑸𝒘𝒑
𝑨𝒑 Width/Diameter
Elastic
Modulus
soil
Poisson’s
Ratio
0.85
Empirical by Vesic (1977)
Perimeter
𝟎. 𝟗𝟑 + 𝟎. 𝟏𝟔 𝑳
𝑫 𝑪𝒑
Empirical by Vesic (1977)
?
𝑪𝒑
53. EXAMPLE 1
▪ Consider a 20-m-long steel
pile driven by a Bodine
Resonant Driver (Section
HP 310 x 125) in a medium
dense sand. If Hp = 350
horsepower, 𝜐𝑝 = 0.0016
m/s, and f = 115 Hz,
calculate the ultimate pile
capacity, Qu .
54. EXAMPLE 2
The allowable working load on a
prestressed concrete pile 21-m long
that has been driven into sand is 502
kN. The pile is octagonal in shape
with D = 356 mm. Skin resistance
carries 350 kN of the allowable load,
and point bearing carries the rest.
Use Ep = 21 x 106 kN/m2, Es = 25 x
103 kN/m2, 𝜇𝑠 = 0.35, and 𝜁 = 0.62.
Determine the settlement of the pile.
62. HOW IT WORKS
SANDY SOIL
𝜂 = group efficiency
Qg(u) = ultimate load-bearing capacity of the group pile
Qu = ultimate load-bearing capacity of each pile without the
group effect
For 𝜼 ≤ 𝟏, or centre-to-centre spacing is small
For 𝜼 > 𝟏, or centre-to-centre spacing is large
66. EXAMPLE
The section of a 3 x 4 group pile in a layered saturated clay is shown in Figure.
The piles are square in cross section (14 in. x 14 in.). The centre-to-centre spacing,
d, of the piles is 35 in.
Determine the allowable load-bearing capacity of the pile group. Use FS = 4.
Note that the groundwater table coincides with the ground surface.
