This section provides a list of frequently asked questions-FAQ on pile integrity test, methods, applications, and limitations in different cases, analysis, and interpretation of test results.
What is Low Strain Pile Integrity Test ?
Pile Integrity Test (PIT), or “low strain impact integrity testing of deep foundation” is a widely used non-destructive test method for the evaluation of pile quality, and integrity. The test can also be used to estimate the unknown length of existing piles and foundations. In the low strain impact integrity testing, the response of the pile to an impact on the head of the pile shaft is determined by a high precision transducer mounted on the pile head. The transducer can either be an accelerator, or a velocity sensor. The test standard allows two different procedures to obtain acceleration and force information: 1) Pulse-Echo Method (PEM) or Sonic-Echo (SE) and 2) The Transient Response or Impulse-Response (IR).
How Many Impact is required for low strain integrity testing?
The general rule for the minimum number of impacts for low strain integrity testing is: The more, the better (assuming that each signal is collected properly). Increasing the number of impacts, and using the average signal will reduce the effect of background noise, and helps enhance repeatable parts of the signal, which will improve data visualization and makes interpretation much easier.
For circular (Diameter less than 500 mm) and rectangular cross sections, place the sensor near the center of the pile and strike several times around the pile head (i.e. 10 impacts).
For piles with larger diameter (i.e. Diameter > 500 mm) additional locations should be considered to obtain useful integrity information about the pile. Choose a minimum of 3 different locations. Collect adequate number of impacts for each location.
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