6. Advantages of Driven Pile
Installation
• Material of pile can be inspected before it
goes into the ground
• Stable in "ʺsqueezing"ʺ ground
• Low risk of damage by ground heave
when driving adjacent piles
• Construction procedure unaffected by
ground water
• Can be readily carried above ground level,
especially in marine structures
• Can be driven in very long lengths
7. • Hard driving may damage or break pile
• Uneconomical if pile design governed by
handling/driving stresses rather than
permanent loading
• Noise and vibration during driving
• Displacement of soil during pile driving
Cannot be driven in very large diameters
• End enlargements not always advantages
• Cannot be driven in low headroom
conditions
Disadvantages of Driven
Piles
24. Why is Vibration Frequency of Importance
for Pile Driving?
• Driving efficiency: pile
penetration is affected.
• Intensity of ground
vibrations: emitted to
surroundings.
• Pile capacity: change of
stress conditions in soil.
25. FV = Me ω2
Centrifugal Force, Fv
s =
Me
mt
Displacement Amplitude, s
Me = ms e
Eccentric Moment, Me
ω = 2π f
Circular frequency, ω
Important Vibrator Parameters
31. 0
10
20
30
40
0
10
20
30
40
14:22:26 14:23:18 14:24:10 14:25:02
FREQUENCY, Hz
VELOCITY, mm/sPRESSURE, MPa
TIME, h:min:s
Pressure MPa Frequency Hz
Depth m Geo z mm/s
DEPTH, m
Ground Response due to Frequency Variation
40. F(t)
uP
(t)
Calculation of Resonance Frequency of Pile
Vibrated into a Soil Deposit
mP
mS
kS
kT
dT
dS
dM
kM
uS
(t)
41. FREQUENCY, Hz
DISPLACEMENT,
mm
Eccentric moment: me=10 kgm -‐‑ Shear wave speed: cS=225 m/s:
Resonance
frequency
Absolute
Imaginar
y
Real
Resonance Frequency of Vibrating Pile
42.
43. Start-‐‑up of vibrator without
vibrations to required speed
without vibrations
Resonance-‐‑free Vibratory Driving
44. Gradual increase of vibration
amplitude rotating lower row of
masses against upper row.
Resonance-‐‑free Vibratory Driving
47. Sheet Pile Driving in Vibration-‐‑sensitive Area
Monitoring of ground vibrations by geophone
Sheet pile driving with resonance-‐‑free, high frequency vibrator
Vibration-‐‑
sensitive
embankmen
t
48. Sheet Pile Driving in Vibration-‐‑sensitive Area
Monitoring of ground vibrations by geophone
Sheet pile driving with resonance-‐‑free, high frequency vibrator
49. Summary and Conclusions
• Driven piles are in many cases a cost-
effective foundation solution.
• Driving piles requires competent personnel
and suitable equipment.
• Vibratory driving can be efficient in suitable
ground conditions.
• By adjusting the operating parameters of
modern vibrators, pile driving and ground
compaction can be optimized.
• The performance of vibrators can be
monitored and opitmized using different
types of sensors.
