Pile testing

Pile integrity testing with sensor

The pile integrity test with sensor (SIT) is in practice also called the sound echo test (SET) or the pile echo test (PET), and belongs to the group of low-expansion tests (LST). The pile integrity test with sensor (SIT) is based on the theory of one-dimensional propagation of waves through the pile, with the aim of determining: actual pile length, existence of defects and discontinuities and reduction of pile cross-section. Also, the following are analyzed: signal change in the pile head domain, signal response quality at the pile base, change in impedance along the pile tree, change in soil layers in which the pile was built and the existence of cross-sectional extension along the pile tree. This test is, in fact, an indirect method of pile integrity analysis, since the test is performed by analyzing the propagation of waves along the pile, but by inducing waves from the pile head. The test is fast, efficient, sophisticated and reliable enough for practical application. This test examines the integrity of all types of reinforced concrete piles: drilled, CFA and beaten. Also, working (exploitation) and trial (test) piles are tested. The sensor integrity testing methodology with the sensor is defined by the ASTM D5882 standard.

The test equipment consists of: a mechanical hammer, a sensor (accelerometer), a hardware system for converting and acquiring data and a software system (PET) for processing and visualizing data (a company from Great Britain - "Piletest").

Three groups of reflectograms can be distinguished: classical or standard reflectograms that indicate good quality of pile integrity, reflectograms that indicate possible reduction of pile integrity, so they require additional analyzes and reflectograms that clearly indicate a more significant problem of pile integrity. A more detailed classification of reflectograms can be carried out according to: - AA - correct spike with positive reflections or when before the reflection from the base of the spike are identified minor changes in velocity and deviations of wave propagation velocity, not more than 5% of average wave propagation velocity; - AB - reflection from the base is not clearly identified, but there are no significant reductions in impedance, and the possible reason for the lack of reflection from the base is the high soil stiffness; - PF - there is one or more negative reflections and / or there is at least one decrease in impedance, and since the reflection from the base is reduced, the impedance is lower than in a defect where there is no reflection from the base; - PD - the speed of wave propagation deviates more than 5% from the average speed of wave propagation, which indicates a possible defect of the pile, where there is one or more reflections that mask the reflection from the base of the pile; - IR - significantly complex signal (response), which, among other things, indicates poor quality of concrete at the top of the pile and / or that the test was conducted too early for the concrete to reach the required strength.


Before conducting the test, the concrete is cut and the head of the pile is cleaned of dust and the remains of broken parts of the concrete. The figure shows the piles (pile heads) prepared for the test of the integrity of the pile with the sensor.

Geomechanical team

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