The construction of driven piles on rock has been practiced for years in Hong Kong. However, detailed field studies to investigate the performance of this type of foundation are still limited. A well instrumented driven H-pile was recently installed and founded on granite. The load transfer mechanism and the pile performance are studied based on comprehensive pile tests. Analyses show that the pile design is controlled by the structural capacity of the pile section but not the engineering properties of the bedrock. The pile toe resistance back-calculated from strain gauges is found to be considerably higher than the allowable values for bored pile design. The Hiley formula commonly used in Hong Kong is found to underestimate the ultimate pile capacity of the pile founded on rock. A more rational wave equation analysis is performed and shows consistent results with PDA tests and the CAPWAP analysis.
Keywords:
Instrumented Pile, Load Transfer Mechanism, Rock, Wave Equation Analysis, Dynamic Formulae
