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RLT

Do steel tubes installed by a vibrator have bearing capacity?

 

Of course! But the real question is: How much? And what will be the load displacement behavior? For a project of TenneT such piles have been tested near Breukelen (NL). The chosen proof load test method was Rapid Load Testing. Typically a job for the Rapid Load Tester of Allnamics, the StatRapid.

 

The steel tubular piles were part of the temporary foundation for a Mammoet mega crane. The load to be lifted over the railway line Amsterdam-Utrecht was a 325 ton transformer. Because insufficient load bearing capacity and/or large deformations could lead to disastrous consequences for the stability of the crane, it was vital to test the piles in advance.

 

It was requested to test as many piles as possible during a normal working day. At 7 am the work could be started with setting up the StatRapid device and at 5 pm testing had to be finished. During this 10 hour period as many as five piles were subjected to multi-cycle load tests. After testing the last pile, the StatRapid device was disassembled and well before dark all the equipment and testing and support teams had left the site.

 

Photo 1 : The assembly of the StatRapid device with the optical displacement monitoring system Reyca in the front

 

Video of setting up the StatRapid for the first test pile.

 

Photo 2 : Testing piles near the railway track

 

In conclusion, thanks to the good cooperation between Allnamics, Gebr. Van 't Hek, VROOM Funderingstechnieken, Joulz and Mammoet, five piles could be tested in one day, all with a positive result. The lifting operation of the transformer was carried out successfully two weeks later.

Photo 3 : The ‘real' test whether the piles where able to carry the full load.(Source: Light at Work Photography, Jorrit Lousberg c.b. TenneT)

 

Do you want to learn more about this project? Click one of the links below.

 

http://www.tennet.eu/nl/nieuws/nieuws/spectaculair-transport-van-loodzware-transformator-naar-breukelen/

 

http://www.tennet.eu/fileadmin/user_upload/Our_Grid/Onshore_Netherlands/Factsheet_Breukelen_SEP2016_web.pdf

 

Do you want to know more about Rapid Load Testing? Please contact Allnamics.

 

Rapid Load Test code published by BSI

 

The BSI (British Standards Institution) has recently published the code for RLT in the UK (BS EN ISO 22477-10:2016). This code describes  Geotechnical investigation and testing; Testing of geotechnical structures; Testing of piles: Rapid Load Testing (RLT).

 

The StatRapid is fully compatible with this code and can be used to determine the static bearing capacity and load settlement behaviour of foundation piles.
 

The code can be purchased in the web shop of the BSI.

http://shop.bsigroup.com/en/ProductDetail/?pid=000000000030292492

 

For more information on StatRapid or Rapid Load Testing you can always contact Allnamics.

 

Do you want to read more about RLT on our website? Click here to search for RLT.

 

StatRapid testing at Yara Sluiskil

 

On the 4th of July 2016 Allnamics checked the capacity and stiffness of 4 production piles (Fundex-type), commissioned by contractor Ballast Nedam Industriebouw BV.

 

The piles are part of the tank foundation for the UREA Granulation 8 Project on the production yard of Yara in Sluiskil, the Netherlands. Rapid Load Testing system StatRapid has been deployed, with which, following CUR guideline 230, the load-displacement behaviour of the piles has been determined.

 

The proof load testing was a contractual requirement and the (positive) results are regarded as representative for the entire tank foundation. Consequently the foundation slab has been cast with high confidence in the foundation design.

str_sluiskil_yara

8MN RLT near Jaarbeurs exhibition centre in Utrecht (NL)

 

In March 2016 Allnamics has performed a 800-ton Rapid Load Test (RLT) on a busy square between Utrecht Central Railwaystation and Jaarbeurs exhibition centre. The test has been performed with the 4/8 MN StatRapid device.

 

The test has been executed together with Brem Funderingsexpertise. With the 4/8 MN StatRapid device, produced by Cape Holland and developed together with Allnamics, loads up to 800 ton (8 MN) were generated, using a drop mass of 40 ton.

 

Photo 1 : 4/8 MN StatRapid device on site at Jaarbeursplein in Utrecht.

Photo 1 : 4/8 MN StatRapid device on site at Jaarbeursplein in Utrecht.

 

The most important test results are available on site (graphical and numerical) on the screen of the field computer direct after each load cycle. That enabled local construction authorities and the main contractor to evaluate the first test results already on site. The printed report was available on the next day.

 

Photo 2 : The StatRapid ready for testing.

Photo 2 : The StatRapid ready for testing.

 

Photo 3 : First evaluation of test results direct after a load cycle.

Photo 3 : First evaluation of test results direct after a load cycle.

 

Compared to traditional static load testing (SLT) StatRapid has the advantage that the required reaction mass can be reduced from 800 ton to 40 ton, the required footprint for testing can be reduced tot approx. 4x4 m² and the total time needed for mobilization, testing and demobilization can be reduced to 1 working day. At the same time the accuracy of RLT results is equal to SLT results for piles in sand, with the results elaborated with the unloading point method, according to the Dutch guide line CUR 230. The same method has been adopted by the Eurocode for Rapid Load Testing, which will be published later in 2016.

 

Compared to dynamic load testing (DLT) StatRapid has the advantage that the accuracy and reliability of the results are much better. Main reasons for that is the fact that load and displacement are measured directly with loadcells and an optical displacement system (instead of derived from strain and acceleration with DLT) and the fact that elaboration of the unloading point method for RLT is user-independent, whereas the elaboration of DLT requires many assumptions and is therefore user-dependent.

 

Compared to Statnamic (another way of doing RLT) StatRapid has the advantage that it does not use combustion fuel and igniters. Storage, transport and use of those are subject to strict regulations, making the test method more expensive and more complex. Next to that, with the StatRapid it is very easy to apply multiple load cycles.

 
For more information on StatRapid or Rapid Load Testing you can always contact Allnamics.
 

StatRapid measurements near Brugge (Belgium)

Using the 8 MN StatRapid Allnamics performed Rapid Load Testing on steel pipe piles for the foundation of the movable bridge over the Boudewijn Canal near Brugge in Belgium in March 2015.

 

The tests were performed on four 1016 mm (40 inch) diameter steel pipe piles with a length of 21.8 m (71.5 ft). Despite the challenging location and site conditions the tests on these 4 piles could be performed in only 2 days.

 

With a drop weight of 40 tons the 8 MN StatRapid can generate the equivalent of an 800 ton static load. As the drop weight lands on a set of special springs the loading characteristic is such that the pile behaves quasi-statically. Consequently the analysis of the test results is relatively simple and the outcome is independent of the results, which is not the case for dynamic load testing.

 

Modular Buildup of the StatRapid

Modular Buildup of the StatRapid

 

As it is modular the StatRapid can be adapted prior to mobilization to suit different pile types and pile lengths. With the AllWave-RLT simulation software the required configuration can be determined in advance.

 

Instrumentation and monitoring

During the test the applied force and the displacement of the pile top are measured. With these measurements the stiffness, load-displacement behavior and the maximum mobilized static bearing capacity of the pile can be determined using the Unloading Point Method (UPM)

 

The force is measured with load cells (A), the pile displacement with an optical measurement system (B and D), and the acceleration with a highly sensitive accelerometer (C). The load cells are placed on a steel plate (F) to distribute the force evenly over the pile cross section. In this particular case a pile drive cap (G) was used as well given the large diameter of the pipe pile.

 

MonitoringSetupStatRapid

Monitoring Setup StatRapid

 

The self calibrating Reyca system measures the pile head displacement accurately through the movements of the black and white bands on the reflector plate (D). Since the band width is known these measurements can even be taken under an angle.

 

The main function of the accelerometer is to register the acceleration of the pile head as a function of time. From these measurements the inertia of the system can be determined. In addition the accelerometer is used to trigger the data acquisition system and through a double integration the measurements provide a redundant determination of the pile head movement.

 

The load cells and the accelerometers are connected to the Allnamics’ PDR (E), the data acquisition system. The measurements are recorded in the PDR’s internal memory and also transferred by WiFi to a field computer running the Allnamics’ RLT monitoring software. With this software it is possible to present the raw data instantaneously in graphical form (as a load displacement diagram). The PDR and the associated monitoring and analysis software make it possible to report the Rapid Load Test results in accordance with ASTM D7383-10 as well as CUR Guideline 230. The latter clearly defines how the measurements are to be converted into the pile’s static load displacement behavior.

 

Several tests around the world have shown that the Rapid Load Test results (using the StatRapid or Statnamic equipment) correlate very well with the Static Load Test results. Mobilization and erection of the equipment, testing of 4 piles (each with several load cycles), and the subsequent dismantling and demobilization of the equipment took only 2 work days for this project.

 

If you need additional information on Rapid Load Testing or the StatRapid (which was developed by Allnamics in cooperation with Cape Holland), please feel free to contact us or download the brochure and/or the technical specifications.

StatRapid Test Location 1

StatRapid Test Location 1

StatRapid Test Location 2

StatRapid Test Location 2

 

RLT on test piles for foundations of wind turbines

 

In November 2014 Allnamics performed Rapid Load Testing (RLT) on test piles for the foundations of two wind turbines near Urk in The Netherlands. Earlier StatRapidUrkAllnamics had performed PDA as these piles were driven into the ground.

 

With a drop weight of 40 tons the 8 MN StatRapid can generate the equivalent of an 800 ton static load. As the drop weight lands on a set of special springs the loading characteristic is such that the pile behaves quasi-statically. Consequently the analysis of the test results is relatively simple and the outcome is independent of the consultant, which is not the case for dynamic load testing.

 

Several tests around the world have shown that Rapid Load Test results correlate very well with those of a Static Load Test. Setting up the equipment, performing the test with multiple loading cycles and taking the equipment down takes less than one day, and depending on the local conditions up to 4 piles can be tested in a day.

 

The first test was witnessed by a large group invited by ENERCON, the project owner, while the second test was witnessed by people invited by Allnamics. Both tests demonstrated that the pile resistance and stiffness more than met the design requirements.

 

If you need additional information on StatRapid, please feel free to contact us or download the brochure and/or the technical specifications.

 

 

StatRapid test in Amsterdam

RLT in Amsterdam

RLT in Amsterdam

 

Allnamics has performed StatRapid load testing for Voorbij Funderingstechniek BV on 2 test piles for high rise building Overhoeks in Amsterdam. De test piles were precast concrete piles, driven in two sections each to 65,5 m depth in a deep sand stratum.

 

 

 

 

 

 

Voorbij StatRapid Allnamics

Voorbij StatRapid Allnamics

DCIM102GOPRO

8MN StatRapid Set Up

 

With the 4/8MN StatRapid device, both piles have been tested within one day, with multiple load cycles to a maximum test load of 8,5 MN (8500 kN or 850 tonnes). The results were immediately available on site and a first draft of the report was issued to the project owner on the next morning. According to these results, the piles had more than sufficient bearing capacity for the design load and had a stiff load-displacement behavior.

 

More information about the StatRapid device. Click here.