2 Proper mounting of the gages Gages have to be attached at least 2 diameters from topPlace each pair of transducers diametrically opposite each otherAlways use a minimum of two strain transducerCan 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 pilesThe two holes shall be placed along the axis of the pile (specially on micro piles)Flat and smooth surfaceDrill perpendicular to the shaftUse washersThe small footings shall be placed towards the pileRange 1000me => 76mm x 0,001 = 0,076mm!!
4 Proper mounting of the gages Accelerometers:Place in line with the axis of the pileThe curved side inUse washersCannot be placed up side downCan 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 hookSteel 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 weightIn case of steel pipe pile filled with concrete, use combined valuesFrequensy of kHz is often OK (1024 samples)kHz => 51 mskHz => 102 ms5 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?BendingProportionality [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 anotherCheck 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 sensorsDPWF – Force/Velocity, Wup/WdnDPE – Displacement/EnergyUse PD and PC to describe the pile and blow (hard to remember afterwards)Use LP (length of penetration)Let someone measure the displacement per blowSave pile in a long descriptive filename
9 PDA-win or PAX-L Is set small <2mm Not mobilized all capacityIf set too high its hard to analyze (CAPWAP) >20mmSet T1 /T2 rise to riseDue to cracking WS and WC can differ for regular reinforced concrete pilesCheck if sensitive to Jc – Use conservative value and confirm with CAPWAP/iCAP