A SIMPLIFIED NUMERICAL APPROACH TO EVALUATION OF RESIDUAL SHAFT FRICTION IN DRILLED SHAFTS

Resumo

Interpretation procedures of load-tests on instrumented piles rely conventionally upon mea-
surements of strains assuming the instant immediately before starting the test as reference configuration

for strains measures. Some experimental evidence shows that concrete in drilled shafts undergoes strains
induced by the curing process comparable in magnitude to the strains measured during the load-tests. It
is therefore expected that mobilization of shaft friction takes place before the load-test. Several authors

have performed experimental and numerical analyses aiming to quantify the influence of those pre-load-
test concrete volumetric strains on the measured bearing capacity using different approaches. The present

work aimed to establish a reference framework for the existing and future works on this topic. In order to
assess the influence of concrete strains induced by curing process on the shaft friction before the start of
the load-tests in drilled shafts, several finite element numerical simulations are performed, considering
the thermal, autogenous and drying strains. The analyses consider concrete as an isotropic linear-elastic
material and the soil as an elastic-plastic material using the Mohr-Coulomb constitutive model natively

implemented in the software ABAQUS. The results are interpreted focusing on the relevancy on the bear-
ing capacity and load distribution along drilled shafts considering or not the strains induced by concrete

curing.