Checklist for PDA

download report

Transcript Checklist for PDA

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 1000 me => 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 , e EA=vEA/(E/ - Check individual sensors (DPFV) r )^½] - For regular reinforced piles wavespeed (WS) can differ from calculated wavespeed (WC) - Wave speed can vary from one blow to another

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