In 1997 CIRIA launched their Integrity testing in piling practice (R144), which formed the primary guide on this topic for the industry. For sometime now there has been concern that even if 100% of working piles are subjected to integrity testing it is unlikely that test results will be a 100% reliable. Furthermore technology has advanced considerably since 1997 and new techniques continue to be developed.
*taken from Cameron G and Chapman T, Quality assurance of bored pile foundations, Ground Engineering February 2004 p35 -40
As a result the Federation of Piling Specialists (FPS) has established a Working Group to evaluate the many new methods of indirect pile testing, to address concerns that exist over their interpretation and ensure results are both robust and calibrated against each other and against existing direct testing methods.
With the development of a number of new methods for the integrity testing of large diameter and deep bored piles, such as Thermal Integrity Profiling (TIP testing) and optical methods, the FPS feels methods need further examination to ensure the data they provide is of practical significance before they become a mainstream choice for specifiers. Presently there is caution that the indirect nature of these new testing methods require ‘calibration’ against previous forms of testing to satisfy specifiers that the testing is reliable, and will provide the same or better ‘visibility’ of a constructed pile and its properties.
Additionally, Sonic Logging, an indirect testing method already well-established, will be examined further with a view to looking at ways of improving safety reducing safety-related issues typically arising during the placement of long telescopic logging tubes in deep bores.
Alasdair Henderson, Chair of the FPS, said: “These new indirect testing methods should be perfect for installation verification of large bored piles used in the foundations of heavy structures and in retaining walls; however it is critical that the data these new testing methods present is reliable and meaningful compared to existing testing methodologies. The primary task of the Working Group will be the ‘calibration’ of these new methods of testing against each other and existing pile integrity test methods so that reliable and meaningful data sets can be produced that not only endure scrutiny, but help promote these new methods to commonplace application.”