Abstract:
Accurate prediction of the bearing resistance of piles which is a combination of shaft and end
resistance is important in the pile design process since if not, it will cause for an uneconomical
and unsafe design. As an alternative method for theoretical formulas, finite element software
such as Plaxis 2D can be used to investigate the behaviour of piles.
This study focuses on investigating the applicability of 2D finite element (FE) modelling in
predicting the behaviour of axially loaded cast in situ bored piles socketed into bedrock under
three main objectives such as investigation of the load-settlement behaviour, mobilization of
skin friction & end bearing resistance. The results of 2D finite element analysis have been
compared with the instrumented pile load test results conducted on 1.2 m and 1.8 m diameter
cast in situ bored piles. The load-settlement behaviour, mobilization of skin friction through
rock and soil layers and the mobilization of end-bearing resistance have been investigated using
2D FE analysis and compared with the results of instrumented pile load tests. The cast in-situ
bored piles have been instrumented using strain gauges at 19 different levels to obtain the
mobilization of skin friction and end-bearing resistance. Instrumented piles were loaded in a
loading cycle including 5 loading stages. The same piles and the loading sequence have been
modelled using the commercially available FE software PLAXIS 2D. It was observed that there
is a high convergence of the results obtained from the PLAXIS 2D model with the actual
instrumented pile load test results for all settlement, shaft friction & end bearing behaviours
with an increment of pile top load. Theoretical capacities obtained for skin friction and endbearing
resistance using the ICTAD guidelines for end-bearing piles have deviated from the
results from FE analysis and instrumented pile load tests.
