Study of the Effect of Sensor Location on Sonic Echo/Impulse Response Testing in Timber Piles

Abstract

Nondestructive Testing (NDT) methods have been utilized to assess the conditions of civil infrastructure in the past decades. Among various NDT methods, Sonic Echo / Impulse Response (SE/IR) is a versatile method to characterize unknown bridge foundations. Numerous numerical and experimental studies have been performed regarding the effect of influencing factors such as the pile-to-soil stiffness ratio, length-to-diameter ratio of the pile, presence of defects and anomalies near the pile head, striking method, and hammer type on the success of the SE/IR method. However, there is a lack of comprehensive study regarding the effect of the sensor location on the SE/IR testing results in timber piles. In the current study, challenges about the location of the sensor are investigated by conducting SE tests on bridges with known and unknown foundations. The results obtained from two accelerometers mounted on the side of the piles showed that the measured length of the piles was more consistent from the accelerometer mounted closer to the top of the pile. The success rate of the SE tests from the top accelerometer was 21.6% greater than the bottom accelerometer. The results of this study were confirmed by numerical simulations. Finally, the Impulse Response (IR) analysis was conducted to support the results. The conducted IR analysis showed that the success rate for the top accelerometer was greater than the bottom accelerometer.