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振动锤 ,
液压振动锤 ,
振力 ,
震动锤液压 ,
电源包 ,
液压动力包 ,
电源包 ,
荷兰国际建筑设备 ,
国际建筑设备 ,
冰 ,
国际建筑设备 (冰) ,
打桩设备 ,
钢板桩 ,
液压动力单元 ,
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The Capability and Versatility of vibratoryhammers and hydraulicpowerpacks
vibratoryhammers and hydraulicpowerpacks are used for driving and extracting piles and steel profiles but also for soil compaction.
vibratoryhammers and hydraulicpowerpacks generate vertical oscillating movements with an average frequency of 1200 to 3000 (20 to 50 Hz) depending on the hammer used. The vibrations reduce or remove the inner soil stresses so only small forces on
the pile are needed to penetrate the soil. The weight of the hammer itself is normally enough to provide for the penetration. However with mounting on a leader with crowd force the speed of penetration can be widely increased.
ICE is manufacturer of vibratoryhammers and hydraulicpowerpacks freely suspended or mounted on excavators.
For technical details about
vibratoryhammers and hydraulicpowerpacks , their design and use,
Please download description:
ICE vibratory hammer and hydraulicpowerpack
ICE vibratoryhammers and hydraulicpowerpacks on a pipe. Note the caisson clamps.
For specifications of the various ICE vibratoryhammers and hydraulicpowerpacks , please click the picture
Rebound
Rebound is the most important cause of damage to vibratoryhammers and hydraulicpowerpacks .
Rebound occurs when the pile stops penetrating by hitting rock or large boulders and the vibrator - in spite of this - is kept vibrating. By rebound the vibratory hammer and hydraulicpowerpack is bouncing on the pile as nearly all the energy
delivered by the vibratoryhammers and hydraulicpowerpacks is reflected from the rock/boulder to the vibratory hammer and hydraulicpowerpack and gives cause to damaging forces.
No operator should operate a vibratory hammer and hydraulicpowerpack without being thoroughly informed about rebound, its nature and its damaging results.
By rebound the vibratory hammer and hydraulicpowerpack must be stopped immediately.
Important about frequencies
The frequency of vibratoryhammers and hydraulicpowerpacks
Normal frequency vibratoryhammers and hydraulicpowerpacks rotate with a speed of between 1200 and 2000 rpm and thereby vibrate with a frequency between 20 and 33 Hz.
High frequency vibratoryhammers and hydraulicpowerpacks rotate with a speed of between 2000 and 3000 rpm and thereby vibrate with a frequency between 33 and 50 Hz.
vibratoryhammers and hydraulicpowerpacks with variable moment - also called resonance free vibratoryhammers and hydraulicpowerpacks - are in general high frequency vibratoryhammers and hydraulicpowerpacks with a design that makes it possible to
run up the vibratory hammer and hydraulicpowerpack to the wished revolutions per minute without vibration. The excentrics of the hammer are then adjusted to make the vibratory hammer and hydraulicpowerpack vibrate the pile into the soil. After the pile
h
as been installed the vibratory hammer and hydraulicpowerpack is run down to zero revolutions without vibration.
ICE vibratoryhammers and hydraulicpowerpacks with variable moment (resonance free) are available.
Natural frequencies and Resonance
The concept resonance is widely misunderstood. Therefore a short description. Every flexible body - also soil - has a natural frequency (also called the critical frequency). If the body is forced by an outside oscillating force to swing at this
frequency, the amplitude of the body becomes as large as it can be and the body is said to be in resonance.
If - as an example - a rotor is rotating at its critical rotational speed, a small outside force on the rotor may make the shaft start to swing and it will be in great danger of vibrating with so large an amplitude that it breaks.
The so-called magnification factor expresses the size of the deflection (amplitude) of the body at the critical frequency. The magnification factor depends on the damping of the body. With low damping the magnification factor is high.
When soil is superimposed with vibrations in its critical frequency area, it will start to swing with high amplitudes. The swinging will propagate to the surrounding area. The amplitude depends on the damping of the soil. The lower damping the
higher amplitude. The result is major or minor disturbances in the form of cracks and dislocations of the ground and often damage to nearby located buildings. The damping in soil depends on soil type, layer distribution, water content etc.
Unfortunately most standard vibratoryhammers and hydraulicpowerpacks operate only slightly above the critical frequency area of the soil. Most soil has a natural frequency between 15 and 20 HZ corresponding to the frequency of a vibratory hammer
and hydraulicpowerpack running at a rotational speed of 900 to 1200 rpm.
In some cases it can be an advantage to utilise a frequency of the vibratory hammer and hydraulicpowerpack near the critical frequency of the soil. This may be the case by concrete pile extraction, but also under certain soil conditions where it
can speed-up the penetration. No building, however, should be close.
For help to choose the right vibratory hammer and hydraulicpowerpack ,
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