Intelligent vibratory hammers

Vibratory hammers are a specific type of foundation equipment, used to drive sheet piles or pipes into the soil. The equipment is used at construction sites for civil works, buildings and offshore structures worldwide, usually under very harsh and demanding conditions. The vibration forces that allow the sheet pile to be driven into the ground are generated by rotating several shafts with eccentric masses attached to them. The current state-of-the-art machines are equipped with a mechanical adjustment mechanism to bring the eccentric shafts in phase or anti-phase, thereby avoiding the particularly damaging low-frequent vibrations during startup and stopping of the vibratory hammer.

International Construction Equipment B.V. is a company that develops and manufactures vibratory hammers and auxiliary equipment like hydraulic power packs for the foundation industry. Their recent merger with PVE Dieseko has strengthened their position as one of the leading manufacturers of foundation equipment for the construction industry.

ICE approached IME Technologies to work out an idea for a new adjustment mechanism that is much less prone to wear. The idea is to develop a hydro-electric control system that enables the adjustment of the relative position of the different eccentric masses. In this way, the harmful vibrations during starting and stopping of the machine can be reduced without the problems associated with wear of mechanical components.

As is common for this type of developments, IME Technologies defined different project phases to provide ICE with the required solution. In the first phase of the project IME Technologies investigated the operating conditions and in particular the vibration levels that the adjustment mechanism should be able to withstand. For this purpose field measurements of the acceleration levels during hammer operation were conducted. Subsequently, different suitable sensors were selected and tested on a vibratory hammer test setup in the hydraulics laboratory of the TU/e. Performance tests showed that the selected sensors provide sufficiently reliable information on the position of the eccentric masses to be used in a shaft control system.

In phase two IME Technologies developed a numerical model that describes the relevant dynamics of a vibratory hammer. Not only does this model provide valuable insights in the relevant dynamics, it will also be used in a later stage to develop a position controller for the eccentric shafts.

In the last phase, IME Technologies worked together with ICE and Parker Haffinin on the selection of a suitable hydraulic system layout and the required actuators to implement the control system. A first step in this phase of the project was the determination of the fluctuations in hydraulic pressure during operation of the vibratory hammer. For this purpose IME Technologies installed various sensors on the vibratory hammer setup and performed measurements at full operating speed.

Finally  IME Technologies implemented the actual position controller that provides the option to operate the hammer both in vibration-free and normal operating mode.