Checklist for PDA

Report
Checklist for PDA-test
Mattias Grävare
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
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!!
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
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
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 10 000kHz is often OK (1024 samples)
- 20 000 kHz => 51 ms
- 10 000 kHz => 102 ms
- 5 000 kHz => 204 ms
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)
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
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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