EP240 type resonance free vibration hammer improves the efficiency of HUW construction method

This issue shares a case study of EP240 resonance free vibration hammer assisting in the construction of HUW method in Kunshan, Jiangsu:

1、 Construction background：

1. A commercial building in Kunshan, Jiangsu uses the HUW construction method for foundation pit support;

2. The soil layer is relatively hard, and the H-shaped steel and U-shaped sheet piles are connected by a locking joint, resulting in high frictional resistance, high end resistance, and low pile sinking efficiency;

3. The verticality of steel piles is difficult to control.

2、 Equipment selection:

Considering the special working conditions on the construction site, the customer selected our company's EP240 electric drive resonance free vibration hammer with a large eccentric torque.

Based on the comprehensive on-site construction conditions, EP240 type resonance free eccentric torque stepless adjustable vibration hammer is selected

2. Considering the actual working conditions on site, it is recommended to choose a vibration hammer with high eccentric torque and large vibration impulse. The EP240 resonance free vibration hammer has an adjustable eccentric torque of 0-150kg * m, a vibration impulse of up to 13506 N · s, and a measured working amplitude of 9-10mm that meets the on-site working conditions. (Table: Basic Technical Parameters)

3、 Feedback on pile driving operation

1. Smooth start stop without resonance: The application of patented technology with infinitely adjustable eccentric torque enables the vibration hammer to start and stop smoothly in a "zero" eccentric torque state, crossing the resonance zone during the start stop process, avoiding damage to the equipment itself and surrounding equipment caused by resonance, and ensuring safety and reliability.

2. Large eccentric moment, large vibration impulse, and high pile driving efficiency: By utilizing the relationship between vibration impulse (I) and eccentric moment (k), as well as angular velocity (ω), and through the scientific combination of large eccentric moment and low vibration frequency, a large vibration impulse is achieved when crossing the hard layer, while avoiding fatigue damage (tearing) to the steel pile caused by excessive excitation force. It is very suitable for pile driving conditions where H-shaped steel is prone to soil blockage and excessive end resistance. The on-site measurement shows that the pile driving time for each 17.5m H-beam is about 10 minutes, and the pile driving efficiency is extremely high.

3. Adjust the torque in real time according to the soil quality, which is more energy-efficient. During the pile driving process, due to the difference in energy consumption among soil layers of different hardness, in the case of softer soil layers, the actual working amplitude can be reduced by adjusting the eccentric torque to minimize the working current.

4. The steel spring has a small damping coefficient and can be lifted with force to ensure verticality. The vibration reduction system uses steel springs, and through optimized selection, its vibration reduction coefficient is not only much lower than that of hydraulic vibration hammers and traditional electric hammers, but also lower than the minimum standard of the vibration hammer industry standard. It is not afraid of damage to the lifting equipment caused by excessive excitation force, and perfectly achieves force lifting to ensure verticality.

4、 Summary

The sinking and lifting of the pile by the vibration hammer should simultaneously meet the necessary conditions of amplitude, power, excitation force, and weight (the necessary force when pulling the pile). It is not solely pursuing large excitation force or amplitude, but rather achieving a reasonable configuration between these necessary conditions according to different soil types and working conditions.