Visual measurement of pile penetration and rebound movement using a high-speed line-scan camera

When a construction company builds a high structure, many piles should be driven into the ground by a hammer whose weight is 7,000 kg in order to make the ground under the structure safe and strong. So, it is essential to determine whether a pile is penetrated into the ground enough to support the weight of the structure since ground characteristics at different locations are different to each other. The paper proposes a visual measurement system for pile rebound and penetration movement including vibration using a high-speed line-scan camera and a specially designed mark to recognize two-dimensional motion parameters of the mark using only a line-scan camera. A mark stacking white and black right-angled triangles is used for the measurement, and movement information for vertical distance, horizontal distance and rotational angle is determined simultaneously. By adopting a line-scan CCD camera whose line rate is 20 kHz, the measurement performance of dynamic characteristics of the pile at impact instant is improved dramatically.