Proceedings - Second International Conference - Piling and Deep Foundations, 1987, Luxembourg, (DFI)
Sonic Integrity Testing
A.F. van Weele; Institute TNO for Building Materials and Structures, Delft, The Netherlands
In general, cast-in-place piles will have an irregular pile shape. However, it is possible that these irregularities are so large that they may lead to pile deficiencies. It is rarely possible to examine the pile foundations visually. Also the performance of a static or dynamic load test on each individual pile is not practical and much too expensive. This is the reason why pile integrity tests have been developed: to reduce the risk of inadequate pile foundations by performing a simple test. Pile integrity tests are non-de- structure tests, which are carried out after a pile has been installed. Over the years, a number of techniques have been developed of which the most important techniques are briefly described in this paper. Of all pile integrity testing methods, Sonic Integrity Testing is the most widely used method in western Europe. This method has been developed by TNO some 15 years ago. Since then the method has been improved, largely due to advances in micro-processing. A major improvement was made by the introduction of digital signal processing techniques. This made the Sonic Integrity Testing method more accurate (smaller defects can be detected), faster (more than 200 piles can be tested on a single working day) and more reliable (the results are easier to interpreted. A few cases will be presented which will show the useful- ness of the Sonic Integrity Testing method. In one of these cases a helpful tool for interpretation of the results is explained: the Sonic Integrity Testing Simulation program, TNOWAVE. Notwithstanding, the fact that Sonic Integrity Testing is a powerful method, it has also some strict limitations. These will be discussed at the end of the paper.
|article #610; publication #40 (IC-1987)|