The length/integrity of piles are quickly and accurately determined using sonic/ultrasonic nondestructive (NDT) testing methods. Complete or partial voiding, cold joints, narrowing (necking) of concrete piles and breaks or partial or complete narrowing due to deterioration of wood piles are conditions that effect the integrity of piles and are indicated by much shorter calculated pile lengths then predicted by as built plans.

1. Field operation with an accelerometer attached to the top of the pile/shaft. The pile/shaft is then lightly hit with a handheld hammer and results are acquired and analyzed by the PIT.
2. Data collection enchancement by time magnification. Further processing yields a plot of an approximate pile shape profile.
3. Capability to optionally transform the data into the frequency domain for mobility analyses and dynamic stiffness determination.

Pile lengths/integrity are determined using a sonic/ultrasonic system that measures and records the end reflected time required for compressional, shear, flexural or torque waves generated and recorded at the top of the pile (see schematic and records over). Pile lengths are determined using reflected wave times; the time of the reflection is a function of the effective length and velocity of the pile. The velocity is a function of the modulus value(s) or strength. Piles constructed of concrete, wood and steel have been successfully evaluated using these methods as well as walls, footings and other structural members.

• Pile Integrity Testing (PIT)
• Pile Integrity Sonic Analyzer (PISA)
• Pile Echo Tester (PET)

Low-Strain Integrity Testing of Deep Foundations

More simply, the PIT is commonly used to:

• profile drilled shafts and cast-in-place piles
• perform post driving testing to evaluate cracks/discontinuities in driven piles

During installation, driven piles may be damaged due to high stresses.  Bored or augered shafts may suffer from separation of concrete, necking, inclusions, voids, bulbing, etc.  It is impractical to statically test each pile.  However, low-strain impact testing utilizing the PIT can quickly evaluate shaft integrity for a large number of piles/shafts at a reasonable cost.

The steps involved for PIT testing generally include: