We have recently been asked the following. I am working with a team of consultants on a pile integrity test on an installed bore pile of 600mm diameter to a depth of 21.00metre.
When I arrived at the site, I requested the pile length. The consultant responded that if our instrument is effective and precise, we do not need any hint but to carry out the test and tell the indication of pile shaft soundness, length of pile installed, and configurations in terms of pile section, necking, and waisting.
Kindly explain why pre-knowledge of pile diameter and length is necessary before commencing the pile integrity test on the field. Answer 1. Setting the planned length sets several parameters in the software, including the expected length scale, the signal acquisition time, and the amplification. Although the length scale and amplification can be changed after the test, the acquisition time cannot. If it was set too short - this data is simply not there - lost.
2. In several cases, the planned depth is critical for the analysis. This is due to the physical effect, in which waves from the hammer impact keep bouncing back and forth in the pile. For example - A 5m pile gives almost an identical reflection to a 10m pile with a necking halfway Compare the two models a & b below by clicking the play button on the Pilewave links below
b. 5m Pile
Both give almost identical reflections - if you expect a 5m pile - it is a good pile (red). If you expect a 10m pile - it is probably a necking (blue).
3. With real-world piles, there are many reflections that can mislead the interpretation. However, when you know the expected length, analysis is much more accurate