Dynamic testing of driven piles in dense sand

For model pile tests conducted in the centrifuge, the transient force of a stress-wave may be measured with strain gauges, however it is difficult to miniaturise the accelerometer needed for velocity measurements. This problem has recently been overcome, by the use of a technique known as a Hopkinson Bar. Essentially, the transient stress-wave velocity is determined by measuring the strain in a subsidiary plastic rod attached near the pile head. High quality force and velocity data have been captured from a thin-walled model pile of prototype dimensions 0.95 m diameter and 20 m in length. The measured stress-wave force and velocity data have been used as input for dynamic analyses, allowing estimates of the static bearing capacity of the pile to be made.