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Rapid Load Testing (RLT)

 Rapid Load Testing

Brochure - StatRapid, A new Rapid Load Testing Application (2939 downloads)

 

With Rapid Load Testing the duration of the load is such that all pile parts are constantly under compression and move in the same velocity range.  This allows the modelling of the pile as a single mass spring system, resulting in a simple straightforward method of analysis, the so called Unloading Point Method (UPM).  

There is a growing awareness that pile capacities determined by High Strain Dynamic Testing with signal matching techniques such as CAPWAP™, DLTWAVE and AllWave-DLT heavily depend on the assumptions made by the person analysing the test results and yield a wide range of results, especially for cast in situ piles (Holeyman et. al. 2001), Viana da Fonseca 2003( International Prediction Event on the Behaviour of Bored, CFA and Driven Piles , Portugal - 2003 (15 downloads) ), Herten et al. 2013( Evaluation of Dynamic Load Tests on bored piles - 2013 (German) (2961 downloads) )).    Consequently it is virtually impossible to calibrate these signal matching based methods against static load tests, since calibration requires consistent results for each method.

This is one of the reasons that in 2010 the Dutch CUR commission adopted the Rapid Load Testing technique (over the high strain dynamic testing) as the results are consistent and virtually independent of the person analysing the test data if the data is analysed with the Unload Point Method (UPM).   

According to this guideline, the load on the pile can be considered a “rapid” load if the duration of the load is longer then 10 times the time it takes for a stress wave to travel from the pile top to the pile toe or in a formula :

 

10 <  T/(L/cp)  ≤ 1000                                 

 

 

where Tf is the load duration, L the pile length and cp the stress wave velocity of the pile material.

  Devices on the market for Rapid Load Testing are:

  •  Statnamic  (STN)
  •  Pseudo Static Pile Load Tester (PSPLT)
  •  StatRapid (STR)
  •  Hybridnamic (HBN)
  •  Spring Hammer (SPH)
Allnamics provides Rapid Load Testing services with Statnamic and StatRapid devices.  Allnamics also supplies components for this equipment (e.g. servo-accelerometers, load cells, spring system materials), complete sets of Rapid Load Testing monitoring equipment (e.g. the PDR and Reyca), and the monitoring and analysis software Allnamics-RLT.
Statnamic devices are manufactured by Berminghammer (www.berminghammer.com)
StatRapid devices are manufactured by Cape-Holland (www.cape-holland.com)
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