Q

Can PIT test results be confirmed by comparing them to piling records?

A

It is advised to always compare PIT results with installation records. This is particularly true for augered cast-in-place or continuous flight auger (CFA) piles. Also, it is advised to compare PIT results with the installation records obtained by a magnetic flow-meter and with depth increments of 600 mm (2 ft) or less (such as the Pile Installation Recorder (PIR) would produce).

Additionally, an engineer should always compare PIT results with the soil profile. Systematic changes in the PIT records may correspond to soil layers. For example, if loose sand overlays a stiff clay, the pile may exhibit a bulge in the sand. But, return to nominal dimension at the clay layer. The relative reduction should not be interpreted as a defect because the nominal diameter was maintained.

Furthermore, engineers should compare PIT records against each other. The comparison will help establish the normal result, as well as identify the records that substantially deviate. This process is particularly important when a reflection indicates a defect (i.e. large reflection with the same sign as the input pulse). In summary, an analyst should consult all available information before determining the final acceptance of foundations using the PIT method.