The Volker Staal en Funderingen (VSF) company digs diaphragm walls for dike reinforcement under very difficult conditions. A 90 t SENNEBOGEN duty cycle crane stands between houses in very tight spaces and digs several meters deep into the ground with a 22 t diaphragm wall grab – a challenge for man and machine.
In the past years, the Dutch civil engineering specialist has put two new SENNEBOGEN 690 duty cycle cranes into service – their most complex application to date is in the Dutch town of Krimpen aan de Lek. Here, a diaphragm wall trench up to 29 m deep has to be dug through the middle of town for dike reinforcement. At times, a duty cycle crane weighing tons is only a few centimeters away from neighboring residential buildings – it is not unusual for the 5 m wide undercarriage and its crawler chassis to stand in a neighbor’s front yard in order to position the 22 t heavy diaphragm wall grab on the opposite side of the street.
Millimeter-precise positioning – diaphragm wall grab with telescopic guide
The basic data of the excavation is impressive: The diaphragm walls are between 26 and 29 m deep and around one meter. A reinforcement cage weighs 15 t, and the construction site is sometimes directly next to houses and down the middle of streets – a challenge for the civil engineering specialists at VSF.
As a result of the local circumstances and because a pile-driving method was excluded due to the fear of building damage, the decision was made in the project planning phase to use the duty cycle crane with diaphragm wall grab. Because there is only little space here to introduce the grapple precisely, the machine was given a telescopic guide on the boom head to keep the grapple on track. This hydraulic guide prevents the rope grab from swinging. In close cooperation with SENNEBOGEN and the local sales and service partner Kuiken NV, the boom was also supplemented with a 1.8 m boom section to be able to mount the grapple while simultaneously keeping the boom dimensions as small as possible for working in tight spaces.
The SENNEBOGEN 690 is equipped with a 447 kW strong diesel engine that reliably drives the two 25 t freefall winches and the additional 11 t auxiliary winch. Operator Rob Lankhorst sits in the comfortable Maxcab and moves the more than 100 t with great precision. Additional surrounding cameras ensure an optimum all-round view, and the circumferential step grids along with the railing on the uppercarriage make daily maintenance especially easy.
In addition to foundation work, the two 690 duty cycle cranes are also used as all-rounders for lifting and loading work. Furthermore, Volker Staal en Funderingen simultaneously works at several sites in this large project and successfully employs a total of five SENNEBOGEN cranes.