This document discusses vibrated and driven piles, including different types of piles and methods of installation. It describes how vibrated pile driving works, noting that vibratory hammers can efficiently install piles through frequency control. Modern monitoring systems allow optimization of vibrator parameters like frequency to maximize penetration rates while minimizing ground vibrations.
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.
