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Checklist for PDA-test

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Presentation on theme: "Checklist for PDA-test"— Presentation transcript:

1 Checklist for PDA-test
Mattias Grävare

2 Proper mounting of the gages
Gages have to be attached at least 2 diameters from top Place each pair of transducers diametrically opposite each other Always use a minimum of two strain transducer Can be ok with only one accelerometer

3 Proper mounting of the gages
Strain transducers: Drill 3” (76mm) between holes (important!). Use drill template on concrete piles The two holes shall be placed along the axis of the pile (specially on micro piles) Flat and smooth surface Drill perpendicular to the shaft Use washers The small footings shall be placed towards the pile Range 1000me => 76mm x 0,001 = 0,076mm!!

4 Proper mounting of the gages
Accelerometers: Place in line with the axis of the pile The curved side in Use washers Cannot be placed up side down Can use one if need be

5 Proper mounting of the gages
Check surface on concrete piles: No crack (if >2m from top often cracks) Not near lifting hook Steel piles: Not to close to weld seam (spiral welded piles) Sometimes need to prepare/grind the steel surface on micro piles

6 PDA-win or PAX-L Prior to test: Check offset (OF-command). Range +-10V
Check that the PDA is working ok by Calibration Test (CT) Enter correct Area, E-modulus, Specific weight In case of steel pipe pile filled with concrete, use combined values Frequensy of kHz is often OK (1024 samples) kHz => 51 ms kHz => 102 ms 5 000 kHz => 204 ms

7 PDA-win or PAX-L Start test: Start of by hitting with a small drop
Works ok? Bending? Hit with higher drop height: Electrical och mechanical noise – Tighten bolts? Bending Proportionality [F=vZ , eEA=vEA/(E/r)^½] For regular reinforced piles wavespeed (WS) can differ from calculated wavespeed (WC) Wave speed can vary from one blow to another Check individual sensors (DPFV)

8 PDA-win or PAX-L Good output quantities:
RMX, VMX, FMX, EMX, TSX, CSX,CSI,RX7,DFN (?) Two letter commands to shift between screens: DPFV – individual sensors DPWF – Force/Velocity, Wup/Wdn DPE – Displacement/Energy Use PD and PC to describe the pile and blow (hard to remember afterwards) Use LP (length of penetration) Let someone measure the displacement per blow Save pile in a long descriptive filename

9 PDA-win or PAX-L Is set small <2mm
Not mobilized all capacity If set too high its hard to analyze (CAPWAP) >20mm Set T1 /T2 rise to rise Due to cracking WS and WC can differ for regular reinforced concrete piles Check if sensitive to Jc – Use conservative value and confirm with CAPWAP/iCAP

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