Evaluation of compression interpretation criteria for drilled shafts socketed into rocks

Abstract

Representative compression interpretation criteria were analysed to assess their relative merits and interrelationships when applied to drilled shafts socketed into rocks. Results of load tests around the world were gathered and collated into a database (CYCU/RockSocket/50) for the assessment. Each of the applied interpretation criteria was then evaluated and compared with one another and with the results of the interpretations of drilled shafts in various soil conditions and post-grouted drilled shafts. To assess the behaviour of drilled shafts socketed into rocks further, interpreted side and end bearing resistances were also determined. The mean interpreted capacities and displacements were higher for drilled shafts socketed into rocks when compared with drilled shafts in soils, but were comparable with those for tip post-grouted drilled shafts. On this basis, recommendations regarding specific interpretation criteria, which are advantageous for design displacement requirements under 12 mm for serviceability and displacements in the range of 53–71 mm for ultimate limit states, were established. Finally, behavioural assessments of the normalised load–displacement curves were extensively conducted using hyperbolic equations to test their effectivity to CYCU/RockSocket/50.