Using of low deformation dynamic tests (Integrity Test System) for quick testing of piles integrity is in common practice in the world. To fulfill pile integrity tests KGS-Astana LLP applies the FPDS SIT-KIT-B method (Foundation Pile Diagnostic System Sonic Integrity Testing – Kit – B). The tests enable to check homogeneity of produced piles and detect hidden defects of piles (different cracks in driven piles, as well as necks and soils inclusions in piles) – look pic.1.
Picture 1. Schematic diagram of piles testing
The core of this method implies the following: a pile head is hammered by a hand hammer, which transmits compression wave along a pile’s surface. Inhomogeneity and a pile’s bottom are reflected by upgoing wave. Installed on the top a very sensitive accelerometer measures the head’s displacement. This displacement is generated by stress wave from the hammer blowing and the following reflections.
For a non-defected pile this method enables to determinate its length. In a defected pile this method also allows to analyze this discontinuous reflection that affects until pile is interrupted. In connection with decreasing or increasing of resistance the wave is reflected by the same signal or a signal with the reversed to the wave interruptions.
One of the main advantages is that the ITS system enables the following: receive required information on piles very fast; uncover different pile’s defects; determine a pile’s length up to 60m.; test any available pile; the minimum inconvenience to a construction process on a site. Thereby the method supposes to fulfill the integrity tests of piles on-the-fly. It is required to test by this method minimum 50% of driven piles and 60% of bored piles. This guarantee the reliability of buildings’ foundation and the further exploitation on a different soils without any damage.
The advantages of the acoustic defectoscopy:
Revealing of any defect in piles on the early work stages;
Only one operator is required to test any available pile;
Possibility to determine a pile’s length;
Very fast and saving method – up to 100 piles per day;
The minimum inconvenience to a construction process on a site