Experience of Sonic Echo/Impulse Response Testing Difficulties in Timber Piles of Bridge Foundations

Sonic Echo/Impulse response (SE/IR) is an economical nondestructive method to collect information pertaining to the unknown bridge foundations. Studies have shown that factors such as the pile-to-soil stiffness ratio, the length-to-diameter ratio of the pile, the presence of the defects, the anomalies near the pile head, the quality of the sensor attachment, the striking method, and the hammer type affect the success of the SE/IR tests. In the current study, numerous SE/IR tests were performed on three known and unknown bridge foundations and the superiority of the time domain analysis to the frequency domain analysis is concluded as an outcome helping engineers conduct SE/IR tests efficiently. In addition, more affecting factors and difficulties specific to timber foundations are identified and discussed. The results presented in this study shows that factors such as the foundation condition, the environmental conditions, and the improper pile-pile cap attachment can also be the sources of difficulties in determining the depth of timber piles.