Key equipment for foundation reinforcement and improvement construction - large eccentric mass moment infinitely adjustable resonance free pile hammer

1、 Application prospects

In recent years, with the strong promotion of super large infrastructure projects (such as airports, docks, and land reclamation) by the country, higher requirements have been put forward for the construction safety, efficiency, energy conservation, and environmental protection of foundation reinforcement and improvement technology. Among them, the vibration sinking stone pile method, especially the large-diameter vibration sinking stone pile method, is an important method for future foundation reinforcement and improvement projects.

2、 Main equipment

1. Pile frame; 2. Resonance free vibration hammer; 3. Pile sinking pipe (including pile tip and feeding hopper); 4. Lift the hopper; 5. Generator;

3、 Construction difficulties

① High end resistance. Due to the closed state of the pile tip during the vibration sinking of large-diameter immersed pipes, the end area of large-diameter immersed pipes is large, resulting in extremely high end resistance. However, traditional vibrating pile hammers have poor effect in overcoming end resistance and low construction efficiency due to their small eccentric mass moment and small vibration impulse.

② Excessive excitation force can damage the pile tube and pile frame. Due to the high end resistance, a considerable portion of the excitation force will rebound upwards during the sinking process and be transmitted to the pile body and pile frame. The obvious mechanical resonance and unreasonable design of the vibration reduction system during the start and stop of traditional vibration hammers have poor filtering effect on vibration, which can easily cause mechanical fatigue and damage to equipment.

Considering the above issues, choosing a pile hammer with high eccentric torque, large vibration impulse, low mechanical resonance hazard, and good vibration reduction effect can improve pile driving efficiency and minimize equipment failure rate and construction safety.

4、 Advantages of EP-B series resonance free vibration pile hammer

The EP-B series vibration hammer has been developed for large-diameter and ultra deep gravel pile sand piles on land, which has the following advantages:

① Large eccentric mass moment and large vibration impulse

A vibrating pile hammer with large eccentric mass moment and large vibration impulse has strong ability to overcome end bearing resistance, especially suitable for foundation reinforcement and improvement (such as sand piles, gravel piles, etc.) construction;

② Resonance free startup and shutdown

The application of the technology of infinitely adjustable eccentric mass moment avoids the occurrence of mechanical resonance during the starting and stopping process of traditional vibrating pile hammers with eccentric mass moment, enabling the machine to start and stop smoothly and freely, and preventing unpredictable damage to the vibrating pile hammer, pile driver, and pile pipe caused by strong vibrations generated by resonance. At the same time, due to the fact that the machine can start under the condition of no eccentric mass moment, that is, no-load starting, it solves the problem of requiring a large capacity power supply for the traditional vibration pile hammer to start under load. The configuration of power supply generally only requires twice the power of the vibration pile hammer motor, which meets the requirements of energy conservation and emission reduction

③ Ultra low damping coefficient

The vibration reduction system adopts a reasonable spring stiffness coefficient and optimized vibration reduction crossbeam. The vibration reduction coefficient is much lower than the industry standard, which can better filter the rebound excitation force, maximize the protection of pile pipes and equipment, ensure construction safety and improve work efficiency.

④ Horizontal structure

The overall structure of the machine adopts a horizontal four axis structure, which makes the operation smoother, safer, and has low working noise; Low temperature rise, able to meet long-term continuous work.

⑤ Adjust different vibration frequencies

By using a frequency converter, different vibration frequencies can be adjusted to meet the requirements of selecting different optimal frequencies for different geological conditions to achieve construction frequency;

⑥ Dual output shaft variable frequency vibration resistant motor

The configured motor is a variable frequency vibration resistant motor with independent intellectual property rights, which has a longer service life. And for the special working conditions of foundation improvement projects, the motor structure is further optimized to have better lubrication and heat dissipation capabilities, making it more suitable for continuous long-term work in foundation improvement projects; On the other hand, both the motor and the vibration pile hammer adopt a front and rear double shaft structure, which makes the force on the motor shaft and the active shaft of the vibration pile hammer more balanced, avoiding the unilateral force on the motor shaft and the active shaft of the vibration pile hammer caused by the traditional single shaft structure on the vibration pile hammer. This can reduce the maximum load of the bearing, reduce the heat generation of the bearing, and improve the service life

EP-B series resonance free vibration pile hammer parameter table:

5、 Construction case

Time: 2022

Project location: Zhoushan, Zhejiang

Equipment: 9 sets of EP550B, 2 sets of EP650B