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PDA

PDR-system used for special bridge project in Cartagena, Colombia

 

For the highway from Cartagena to Barranquila, Colombia, the approx. 6 km long bridge “Viaducto Gran Manglar” is built just north of Cartagena through a shallow lagoon with mangroves.

 

Mangroves are protected vegetation and therefore a construction method with minimal environmental impact was required. The contract was awarded to the Italian contractor Rizzani de Eccher who proposed to build the bridge from a launching gantry, using precast concrete elements.

 

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This very special construction method – developed by Canadian piling & equipment company Berminghammer - has a minimal impact on the surroundings, because the footprint of the construction work is the same as for the bridge itself: the gantry rests on the front end of the already completed part of the bridge and cantilevers to the location of the next pier. At the front of the gantry the piles for the next pier are installed, while at the back the main girders of the bridge deck are installed. These girders (just as all other construction materials) are transported over the already completed part of the bridge instead of through the lagoon, further reducing the environmental impact.

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Essential for this construction method is the verification of the foundation piles’ bearing capacity for each of the 129 piers within hours after installation, because the piles will have to bear their maximum design load 72 hours after driving. For this reason Rizaani chose to purchase Allnamics PDR-systems and AllWave software, and have their staff trained on site by Allnamics. This enabled Rizzani to perform PDA and subsequent signal matching themselves, with Allnamcis support (both on site & remote). Rizzani also contracted Allnamics to perform the dynamic monitoring of the test piles and the development and implementation of the pile driving and acceptance criteria.

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The construction method with the launching gantry allows the entire bridge to be built with precast pre-stressed concrete elements. For production of these elements – piles, pier caps and bridge girders – a complete precast yard has been built next to the northern abutment of the bridge. All elements are then transported to the rear of the gantry, using the already constructed part of the bridge.

 

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The launching gantry consists of 2 parallel truss bridges, and  rests on 2 main support beams that are placed on already installed piers.  From there the gantry cantilevers approx. 50 m, just past the loacation of the next pier.  Running over the top of the gantry are 2 cranes and at the front there is a leader system, equipped with a Berminghammer B6505-HD diesel hammer.

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The hollow concrete piles with a diameter of 1,0 m and a length of up to 55 m are driven in 2 sections that are jointed together with a custom designed mechanical splice . The cranes move the pile sections from the rear to the front of the gantry where it is placed into the leader. Next the leader  is erected vertically, after which the pile section is driven. Once the pile section is installed the leader is lowered back to the horizontal position sothe next pile section can be accepted.

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After all 6 piles for the pier have been installed, they are cut off and a precast concrete cap is mounted over the pile heads. Once a temporary support is placed between this pile cap and the gantry, the front main support can be moved to this new pile cap and the rear main support is also moved up one pier. Then when both main supports are in their new position, the whole gantry is moved one span forward (approx. 37 m), with the leader ending up just past the location of the next pier to be constructed. But before the piles for that pier are driven , the girders for the bridge deck are mounted up to the just finished pier.

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With the launching gantry working at its normal pace, this installation cycle takes 3 days. For that reason the piles will get their maximum design load after 72 hours, when the gantry with leader cantilevers just passed the freshly installed pier cap. In each cycle, the pile bearing capacity needs to be verified in time for that.

 

Rizzani started piling at the north end of the bridge in August 2016 and will soon start with a second gantry at the south end.

 

For dynamic pile monitoring on two fronts Rizzani has purchased a second PDR-system.

 

 

Video of Berminghammer.

 

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!

 

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Photo 1 The Blue Hammer from Fistuca

 

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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.

 

Dynamic Pile Testing for Amstel Towers Hotel in Amsterdam

 

In April 2016 Allnamics has performed PDA-monitoring and DLT-testing for our client Voorbij Funderingstechniek BV, for the Amstel Towers Hotel near Amstel station in Amsterdam. The tests were done on 51 m long precast concrete piles, driven in sections, with a mechanical joint.

 

PDA monitoring (Pile Driving Analysis) was done during full installation cycles of selected production piles. Main goal of the test was to check the tensile stresses during driving, in particular at the location of the mechanical joint.

 

DLT-monitoring (Dynamic Load Testing) was done during restrike (approx. 10 blows) on piles that had been installed a couple of days earlier. Main goals of this test were to check the strength of pile shaft and joint and the static bearing capacity  of the pile.

 

Both tests were performed with the in-house developed Allnamics PDR-system, fitted with combined strain and acceleration sensors, which were mounted near the pile head. The PDR reads and stores the monitoring data real time and transmits them with a wireless connection (by WiFi) to the field computer of the monitoring engineer. The wireless connection offers great advantages during upending and positioning of the pile and makes it possible for the monitoring engineer to do his monitoring job on a good location, at a safe distance from the pile and without traditional worries about the long cable getting stuck or damaged during handling or piling.

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Photo 1 : Monitoring with WiFi connection, at a safe distance from the pile

The tests showed that the tension stresses during driving were acceptable and that the available static bearing capacity is sufficient for the design loads of the piles.

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Photo 2 : no trouble with long cables during upending of the pile

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Photo 3 : pile and monitoring equipment at end of PDA

Recorder function of PDR used for offshore PDA-test

 

In september 2015, Allnamics was asked to monitor stresses in the flange and on the inside of a monopile for an offshore windfarm, during installation of the pile with an impact hammer. Special challenge was that all the instrumentation had to be mounted on the inside of the pile, with limited space AFoto01available for placing sensors and equipment. On top of that, drilling and welding were not allowed and the test had to be completed within 3 weeks after the first enquiry. The recorder mode of the Allnamics PDR, ingenuity and improvisation made it possible!! AFoto02

 

The instrumentation consisted of 2 acceleration sensors placed vertically, 2 horizontal strain gauges on the flange and 4 vertical strain gauges on the inside of the pile wall; this setup also incorporated a “normal” PDA (Pile Driving Analysis) setup. 2 PDR-systems were used for data acquisition of these 8 channels, with the acceleration sensors used for triggering.

 

Challenges

Main challenge for this project was that the instrumentation had to be installed on the inside of the pile, because of the hammer sleeve. Obviously this would make it impossible to establish a wireless connection to a computer on the vessel. But a cabled connection was also not possible, because the pile did not contain a cable outlet hole or snorkel hole near the pile head and below the hammer sleeve.Measuring on the inside of a pile without any communication from the outside was solved by using the Allnamics-PDR in recorder mode. All monitoring data were saved and stored in the PDR-systems during pile installation and transferred to a computer after they were retrieved from the pile.

 

Figure 1 : Configuration D: PDR operating in recorder mode

Figure 1 : Configuration D: PDR operating in recorder mode

 

The required battery life time of the PDR needed to be approximately 12 hours. The installation cycle was expected to be around 3000 blows By using an external battery the monitoring time could be extended to 12 hours. The standard memory is already able to record 10.000 blows.

 

Positioning of sensors

Next challenge was the restrictions imposed by the space that was needed for the grippers of the upending tool and an airtight platform that had to be mounted inside the pile, before removal of the equipment. This required mounting of the instrumentation above the platform, less than 1 m below the pilehead. All in all very little space for positioning the sensors and recorders was left.

 

Photo 1 : The gripping tool just before pile upending

Photo 1 : The gripping tool just before pile upending

 

 

Photo 2 : airtight platform in mobilization port

Photo 2 : airtight platform in mobilization port

 

Photo 3 Finding space to place sensors and monitoring equipment (pile in horizontal position)

Photo 3 Finding space to place sensors and monitoring equipment (pile in horizontal position)

 

Mounting of sensors

The next challenge was the way to mount the acceleration sensors and the PDR-systems without drilling holes in the pile or welding on the pile. For the strain gauges (and their tension relief) this was solved by glueing them on the pile. For the acceleration sensors this was solved by adapting their housing, so they could be bolted to the earthing stubs that were already inside the pile.

 

hoto 4 : Earthing stub used for mounting the acceleration sensor and the strain gauge glued directly on the pile

Photo 4 : Earthing stub used for mounting the acceleration sensor and the strain gauge glued directly on the pile

 

For suspension of the PDR-systems this was solved by placing wooden stub between the flange and the platform ring. The stubs were kept in position by using the bolt holes in the flange and the stiffener plates of the platform mounting ring. Each PDR was suspended between 2 stubs, with elastic bands.

 

Photo 5 : One of the 2 PDR’s mounted between 2 wooden stubs (pile in horizontal position)

Photo 5 : One of the 2 PDR’s mounted between 2 wooden stubs (pile in horizontal position)

 

Execution of the project

Next challenge was to prepare and monitor the project within 3 weeks from the first enquiry. The mounting of the sensors had to be done outdoors, in the mobilization port prior to pile installation on site. Conditions were quite hostile that day, cold and very windy!

 

 

 

Photo 6 Installing the sensors from a cherry picker: 2 acceleration gauges & 6 strain gauges

Photo 6 Installing the sensors from a cherry picker: 2 acceleration gauges & 6 strain gauges

 

But al sensor mounting and glueing went smooth and successful. After all these challenges were solved, there was one more left: Allnamics had no monitoring specialist available in the planned time frame for the offshore testing campaign….  Luckily our German partner company Fichtner could provide us with one of their specialists to do the job offshore!  The PDR’s were successfully retrieved and had recorded all blows, giving the client valuable information of the pile during driving without disturbing the production process.

 

Photo 7 : The piles on deck of the installation vessel

Photo 7 : The piles on deck of the installation vessel

 

Photo 8 : Bringing the pile in position

Photo 8 : Bringing the pile in position

 

Photo 9 : Hammering down the pile down

Photo 9 : Hammering the pile down

 

Photo 10 : Exciting moment: just after lifting the hammer

Photo 10 : Exciting moment: just after lifting the hammer

 

Photo 11 : The equipment after pile installation and installation of the airtight platform.

Photo 11 : The equipment after pile installation and installation of the airtight platform.

 

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

PDA monitoring at research project in Middenbeemster (NL)

 

In March 2016 Allnamics took part in a research project establishing a relation between pile driving and vibrations in a building as a function of distance. Within this project strains and accelerations in the steel tubular pile during driving were recorded with the Allnamics PDR-system for Pile Driving Analysis.

 

With the monitoring and processing software the recorded strains and accelerations are analysed and forces, velocities and stresses (and other quantities) acting on the pile during driving can be calculated. A selection of photographs covering this research project is presented below. During driving a variety of monitoring in and at the building was conducted. Among others vibration monitoring with multiple systems was performed and accelerations and strains were recorded in the masonry at various locations. Because the building had to be demolished for erecting the new headquarters of piling contractor Gebr. Van ’t Hek the test pile could be driven in extreme close proximity of the building. Apart from Allnamics, Fides Expertise, TNO, Leiderdorp Instruments and Hektec were involved in the research project.

 

In case you are interested in more information on Pile Driving Analysis or this particular research project, please feel free to contact us.

 

Instrumentation on pile prior to lifting.

Instrumentation on pile prior to lifting.

 

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Strain monitoring masonry on both in- and outside of building.

 

Vibration monitoring building with geophones and accelerometers.

Vibration monitoring building with geophones and accelerometers.

 

Vibration monitoring inside the building with geophones and accelerometers.

Vibration monitoring inside the building with geophones and accelerometers.

 

Pile driving as close as possible to the building.

Pile driving as close as possible to the building.

 

The instrumented, driven pile (on the right) and a selection of structural monitoring sensors attached to the building.

The instrumented, driven pile (on the right) and a selection of structural monitoring sensors attached to the building.

 

Dynamic testing piles OWF Westermeerwind NL

Westermeerwind

Hammer on the steel monopile

 

In May 2015 Allnamics performed Pile Driving Analysis (PDA) during the installation of 5 monopiles for the wind farm Westermeerwind in the Dutch IJsselmeer using the Allnamics PDR.

 

The marine part of the Westermeerwind project consists of 48 wind turbines of 3 MW each. The foundation for these turbines is a steel mono pile with a diameter of 5 m (17 ft) and a length between 35 and 45 meters (100 to 150 ft). The piles were driven to depth using a hydraulic impact hammer IHC S-800.

 

The measurements were taken with Allnamics’ wireless PDR system. Prior to transport to the job site the sensors and sensor cables were mounted on the pile at the fabrication yard in Flushing in the South of the Netherlands. On the day the pile was driven into ground the PDR was mounted and connected to the sensors. The system then recorded for each hammer blow all relevant data, incl. the impact energy of the hammer, the compressive stresses in the pile and the dynamic pile resistance. In this particular case the owner was mainly interested in the maximum stresses during each blow to ensure that no unacceptable pile driving fatigue damage occurred.

 

If you need additional information on the PDR, please feel free to contact us or download the PDR brochure.

 

Do you want to know more about the project Westermeerwind? The Dutch website is : http://www.westermeerwind.nl.

 

Do you want to see a video of the pile driving process? https://vimeo.com/allnamics/allnamicspdawestermeerwind

 

Lifting the pile

Lifting the pile

PDR and the combined sensors mounted on the pile.

PDR and the combined sensors mounted on the pile.

 

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Overview of the pile and hammer near the end of driving. Copyright ; Ruud Ploeg Fotografie

 

Dynamic Foundation Measurement training for BAM International

Day 1 Theory First

 

In February 2015 Allnamics trained 6 staff members of BAM international in the use of the Allnamics’ PDR for proper data acquisition during Pile Driving Analysis and Dynamic Load Testing.

 

As usual the training started with a day in the Allnamics office to cover the theory, during which the trainees had to derive equations for the one-dimensional wave theory. For some this is pretty tough, but after this session participants always have a good idea of what happens in a pile as it is driven into the ground and they can not only interpret field measurements but also distinguish between good and bad data sets.

 

The second day was a field day. Thanks to the company Hektec all trainees had the opportunity to install sensors as well as connect and operate the equipment. This is important aspect of mastering the process, and with these sensors real data was then obtained during an actual hammer blow later in the day.

 

The third and final day was back in the office, during which not only the data collected the previous day were reviewed, but also many data sets from projects Allnamics performed over the years around the world.

 

Obviously the training does not necessarily end at the end of this third day when the participants leave with the course material. Allnamics staff is always available to support the course participants whenever they need some additional help.

 

If you want to know the participants’ take on the course click here to read their report on the BAM International website.

 

With the PDR data can be acquired to monitor the pile driving process but it can also be used during Static Load Testing (SLT) and Rapid Load Testing (RLT) of deep foundation elements.

 

If you need additional information on the PDR or a training course StatRapid, please feel free to contact us or download the PDR brochure.

 

Day 2 Dry Practice

Day 2 Dry Practice

 

Day 2 Overview test location

Day 2 Overview test location

 

Day 2 Two groups who can drill best

Day 2 Two groups who can drill best

Day 2 Sensor on the pile group 1

Day 2 Sensor on the pile group 1

6 BAM Day 2 Sensor on the pile group 2

Sensor on the pile group 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Day 2 Examining the data

Day 2 Examining the data

 

Day 3 evaluating and understanding data

Day 3 evaluating and understanding data

Dynamic and Static measurements at 40 m waterdepth

Overview testlocation

Overview testlocation

 

To optimize and certify the final design of the Wikinger Offshore Wind Farm (OWF) in the Baltic Sea near the German island of Ruegen, the project owner, Iberdrola Renewables, initiated a test program, whereby test piles were installed at the planned location of 3 wind turbines in 40 meter deep water.

 

During the first phase the test piles were driven into the sea floor as Pile Driving Analysis (PDA) measurements were taken using underwater sensors. In addition signal matching was applied on the measurements during the final hammer blow to predict the mobilized static bearing capacity of each pile.

 

After a set-up period of approx. 13 weeks the second phase took place, during which at each location one test pile was subjected to a static tensile load test (up to 15 MN) while the other pile was subjected to a high strain dynamic test. For the latter signal matching was applied on the first restrike to predict the mobilized static bearing capacity (incl. the set-up).

 
Among the many project challenges two must be mentioned:

First of all there was the design and construction of an assembly to perform static load tests under water. In a joint effort between the construction contractor Bilfinger Marine & Offshore, engineering firm Fichtner Wind & Water, the Norwegian Geotechnical Institute NGI and Allnamics a practical, innovative and re-useable assembly was developed that can be installed from the vessel deck without diver intervention.

 

Secondly the underwater sensors had to remain functional for at least 3 month in salt water at a water depth of 40 meters (so they could be used during the second phase). The sensors supplied by Allnamics all met this challenge. Apart from supplying the sensors Allnamics was also contracted by Bilfinger to perform and evaluate the static and dynamic load tests of the test piles. These tests were performed using the PDR, a state-of-the-art multi-purpose monitoring system that can also be used for Rapid Load Testing.

 

For more details about this project click here to see a movie made by SAL Offshore, and in case you would like more information on the PDR or underwater testing, please feel free to contact us or download the PDR brochure.

Underwater Sensors (UW)

Under water Sensors (UW)

 

Pile Driving Frame

Pile Driving Frame

4 Paal tijdens het hijsen dichtbij

Pile with sensors during lifting

5 Paal tijdens het hijsen

Pile during lifting

6 Aansluiten sensoren op de PDR

Connected double sensor set on both PDRs

7 Menck Hamer

Menck Hamer

8 Meten tijdens het heien

PDA Measuring during driving

10 Ophalen kabels na 10 weken op de zeebodem

Retrieving cables after 10 weeks at a water depth of 40 meters

 

11 Aansluiten kabels aan de meetapparatuur

Connecting the cables on the PDR monitoring unit

12 Statische proefbelasting

Measuring during SLT

13 Eenvoudige voorstelling van meetsetup

Simple explanation of the measurement setup

14 Meetframe SLT

Static Load Testing Frame

15 Reactieframe in Water

Reaction frame

16 Onderwater robot

ROV

17 Onderwater sensoren

The UW sensors

PDA on test piles for foundations of wind turbines

 

In October 2014 Allnamics performed PDA on test piles for the foundations of two wind turbines near Urk in The Netherlands.

 

The foundation for these wind turbines, which have a tower height of more than 100 meters (330 ft) and a capacity of 7 MW, each consist of 60 prefabricated square concrete piles (500 x 500 mm2, 20 x 20 in2) with a length between 19 and 23 meters (63 and 77 ft)

 

The PDA was performed with Allnamics’ wireless PDR, which allowed for registration and recording of all relevant hammer blow data, such as the transferred energy, the stresses in the pile and the dynamic pile resistance.

The end-of-drive data for each test pile were analyzed using Allnamics-DL signal matching software to determine the lower limit of the static pile resistance.

 

Shortly thereafter these piles were subjected to a Rapid Load Test using Allnamics’ StatRapid.

 

PDR and the combined sensors mounted on the pile

PDR and the combined sensors mounted on the pile

PDR aan Prefab Paal Urk Tijdens Hijsen

PDR on the pile during lifting of the pile. (No measuring cable)

PDR aan Prefab Paal Urk Tijdens Heien.

PDR on the prefab pile during driving and sending wireless the data.