In this video, we will be discussing low strain impact integrity testing for deep foundations and piles.
Low strain pile integrity test is a common nondestructive test (NDT) procedure for quality control and quality assurance (QC/QA) in deep foundation construction. The test can be used to identify physical defects (voids or discontinuity, referred to as pile integrity) in piles, or determine unknown length of existing deep foundations.
Low Strain Pile Integrity Test belongs to the family of shaft head impact tests, where the response of an impact made on the head of pile head is recorded by a motion transducer (i.e. accelerometer), and used for analysis. Alternatively, engineers can use other tests such as crosshole or down-hole tests for the purpose of integrity test.
Pile Integrity Test (PIT) is normally performed by striking the pile head with a light hand-held hammer and recording the response of the pile using a motion transducer (i.e. accelerometer) coupled to the pile head. The hammer strike (blows) generate compressive stress wave that will travel through the pile. This wave is partly reflected from the pile toe or other anomalies within the pile in its way back to pile head. Any change in impedance (due to change in pile cross section, concrete density, or shaft-soil properties) within the pile can impact the reflecting signal.