Predicting the capacity of pulse piles

Pulse piles have been successfully used in geotechnical construction for last 25 years. This type of mini piles has proved to be very useful on the restricted access sites and provide a cost effective solution in comparison to the conventional piling techniques.
The shockwave created by an electric arc discharge in wet grout reaching the walls of a borehole provides enough pressure to create local failure of the ground surrounding the point of discharge. This phenomenon known as Electrohydraulic effect applied along the shaft of a pile increases the diameter of a pre-bored hole, changes shape of pile-soil interface and improves shaft friction and end-bearing of the resultant pulse pile.
The design approach is based on calculation of shaft friction and end bearing of the bored pile using empirical coefficients obtained from the load testing. Pulse discharge technology has been used in Russia and South Korea, therefore additional work was required to provide theoretical basis for design procedure in accordance with Eurocodes and British Standards.
This research focuses on prediction of capacity of a pulse pile in coarse and fine grained soils. A finite element 2D axisymmetric model was developed to simulate construction sequence of a bored pile in Plaxis software. The calculated settlement from a vertical load applied at the top of pile has been compared to the results of semi-empirical calculations of pile performance. Full-scale field test results were used to validate methodology of both calculation methods.