The arching mechanism in piled embankments under road and rail infrastructure

It is becoming increasingly necessary to construct road and rail networks on ground that was once considered unsuitable. Traditional methods of construction require prolonged construction periods and thus increased cost. An alternative method of constructing on soft ground is the use of piled embankments, which significantly reduces construction times as well as reducing differential settlements. Several design methods are available for estimating the magnitude of arching, however significant inconsistencies between these design methods have been found. A laboratory investigation, using a 1:3 scaled model was used to investigate the influence of pile and embankment geometry and embankment strength parameters on the magnitude of arching. The results from the experimental model have been compared to current design methods using the stress reduction ratio, and were found to be within the range predicted by the Terzaghi (1943) and Hewlett & Randolph (1988) arching theories.