Vertical and lateral load tests on driven cast in place piles at Yarmouth

The Building Research Establishment (BRE) assisted with the vertical and lateral load testing of driven and bored cast-in-place piles, that had been installed through soft alluvial deposits and founded in a dense sand layer. The results of a BRE base load cell installed in one of the piles tested under vertical load, showed the importance of the drilling out procedure on the base resistance of the piles. The monitored base resistance was found to be significantly less than could have been predicted by current design methods. An electro-level system installed in a second pile, loaded laterally, provided detailed information on the performance of the pile that allowed a critical appraisal to be made of several current design methods. The findings show the potential dangers of attempting to get improved design parameters from only limited performance data. The formation of a plastic hinge in the pile during the tests was deduced from the electro-level results. This was observed in the head load/movement plot as only a small change in slope.