Pile Testing: Anomalies, Flaws and Defects By Joram M. Amir, Ph.D., C.E., D.GE, Piletest.com Ltd.
Pile integrity means strict adherence to the relevant drawings and specifications. This includes the pile geometry (e.g., length, diameter or width, and verticality) as well as continuity and material properties. Since the construction process of piles is practically blind, practitioners realized early on that pile integrity should not be taken for granted. Starting in the early 1960s, the discipline of pile integrity testing has made giant steps in both testing methods and their implementation worldwide. Presently, the prevalent methods are the low-strain impact method (ASTM D5882, Standard Test Method for Low Strain Impact Integrity Testing of Deep Foundations) and the crosshole ultrasonic method (ASTM D6760, Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing). In comparison with the widespread advancements in instrumentation, the piling industry has not yet reached a consensus regarding the interpretation of the test results and acceptance criteria. Often, this creates unnecessary friction and even litigation between the parties involved. To avoid these consequences, the parties must first agree
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about the facts by adopting established definitions to the following three terms that today are often confused: anomaly, flaw, and defect. The following sections suggest such definitions, which are supported by commonly occurring examples.
Definitions Based on the technical paper by Amir, “Single-Tube Ultrasonic Testing of Pile Integrity,� which was published in the proceedings of the ASCE 2002 Deep Foundation Congress, the following definitions are intended to make a clear distinction between the results of the integrity tests, the physical condition of the pile and the necessary action, if any. The terms were incorporated in ASTM D6760 and can also be visualized using a Venn diagram in which they can be depicted and distinguished. Anomaly: Any irregular feature in the results from the nondestructive testing (NDT). An anomaly may be due to the testing instrument (e.g., noise), the means used (e.g., access tube debonding), the surrounding soil (e.g., abrupt changes of soil friction) or the pile itself.
