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Research

Vibration monitoring research project at Terneuzen, NL

 
On August 8th and 9th, 2016 Allnamics performed, together with Fugro and Fides, vibration monitoring at a test location in Terneuzen NL.
 

At the test location several abandoned buildings were available for monitoring the vibrations caused by a test drive of 3 large diameter steel tube piles. The piles were vibrated in up to refusal and then driven to final penetration with a large hydraulic hammer. This presented the researchers the opportunity to examine the buildings while being exposed to large vibrations and assess whether the building showed any resulting damage.
 
The vibration monitoring was carried out with 24 monitoring systems with 3 channel geophones on 4 separate buildings. The results of the measurements have been submitted to the SBRCUR committee updating the guidelines on vibration nuisance.

Photo 1 : The Vibro hammer PVE 2350 VM

Photo 2 : Vibration Monitoring during impact driving.

Photo 3 : Vibration monitoring on 4 different buildings with 24 systems.

Photo 4 : Vibration Monitoring at ground level

Photo 5 : Monitoring at corner of building at roof level

 

 


 
More information about vibration monitoring.
 
Or
 
Contact our office in Heemskerk
 


 

Strain gauge monitoring

 

One of the monitoring techniques in our portfolio of services is (dynamic) strain monitoring with strain gauges directly glued-on the (steel) surface.

 

Allnamics has been involved in (dynamic) strain gauge monitoring for a long time, mostly for PDA (Pile Driving Analysis) monitoring during impact driving of foundation piles. Because the sensors have to sustain severe dynamic loads during impact driving (accelerations up to than 1000 x gravity or more), the strain sensors are traditionally bolted in holes that are drilled in the pile wall.

 

However, drilling is not allowed or simply impossible in more and more cases. Allnamics has been able to solve this issue by glueing the strain gauge and its sensor cabling directly on the steel surface.

 

This technique has been succesfully used for PDA-monitoring during a pile driving test in Kinderdijk (NL) and during installation of monopiles for several offshore windfarms. The same technique, that in principle can also be applied for other sensor types or larger elements, has been used for a structural health monitoring project near Delfzijl (NL), with the sensors functioning for several months.

 

You want to learn more about this service?

 

Take a look at our product page strain gauge monitoring or contact us.

 

PDA monitoring for new Blue Piling hammer with 4000 ms samples

 

In spring of 2016 Allnamics was involved in monitoring the performance of a prototype of the new developed Blue Piling hammer. The performance tests were done in the Caland Canal in the Rotterdam Harbor, on a dedicated 140 m long test pile. This pile has sufficient resistance for pile driving hammers with a large energy output. In January 2013, at the same location, Allnamics was also involved in a PDA test for the acceptance of the (at that time) largest hydraulic hammer in the world, the Menck MHU 3500 S.

 

The Blue Piling hammer type is developed by Fistuca. Its working principle is explained on the website of Fistuca and is different from traditional hydraulic hammers or diesel hammers. One of the differences is the much longer load cycle duration of a single hammer blow.

 

The monitoring had some special requirements. First, next to the pile, also the housing of the hammer had to be monitored. Second, because full loading cycles had to be monitored, measurement samples of 4000 milliseconds had to be recorded. For the 140 m long test pile, this corresponds to approx. 70 stress wave periods (2*L/c). For standard PDA monitoring, international standards (ASTM, Eurocode) require a minimum sample duration of 6-8 stress wave periods, at a sample rate of at least 10 kHz. With the Allnamics PDR-system and Allnamics-PDADLT software, it was possible to monitor pile and hammer simultaneously for 4000 ms at 12.5 kHz sample rate during each blow. A new milestone!

 

Fistuca1

Photo 1 The Blue Hammer from Fistuca

 

Fistuca2

Photo 2 PDA Measurement with the PDR and sensors on the pile and hammer housing.

 

After instruction and training by Allnamics staff during the first day, engineers from Fistuca performed the PDA measurements themselves. For a period of 1 month the equipment was continuously exposed to humid and salty weather conditions, performing 100% of the time. This was another milestone in endurance of the equipment.

 

 

 

In case you are interested in more information on Pile Driving Analysis, Hammer monitoring or the PDR-system, please feel free to contact us.

 

Research project DOT500 – Vibratory Driving Prediction and Analysis

 

On May 6th 2016 a monopile foundation has been vibratory driven into the ground for a full-scale test of a newly developed wind turbine.

 

Allnamics performed vibratory driving predictions in order to quantify the required vibro hammer (CV320). During actual installation Allnamics performed so-called VDA monitoring. The Vibratory Driving Analysis results in records of strain and acceleration in the pile. This offers the possibility to verify assumptions made for the prediction and consequently effectively close the double loop of the learning system.

 

The time-lapse presented below offers an impression of the monopile installation.

 

 
 
If you want more info about VDP or VDA?  Contact us!
 
More info about the CV320 or Cape Holland ?
 
More info about the DOT500 ?