The behaviours of four foundation pilings (ϕ=0.41 m) constructed in Foz do Iguaçu, Paraná (PR), Brazil and subjected to slow loading tests were analysed. The results were compared with results from three-dimensional numerical modelling using the finite element method, which facilitates simulation of the elasto-plastic behaviour of soil. The local subsoil comprises varied stratigraphies; it is composed of a residual soil surface layer followed by weathered rock and bedrock, which are a few meters deep. The massif geotechnical parameters were determined through correlations obtained from field tests, whereby the values for cohesion, angle of friction, modulus of deformability and uniaxial compressive strength in the different subsoil layers were estimated. The load tests were interrupted at 3000 kN and displaced by less than 5 mm in the working load (1500 kN). The pilings were subjected to lateral friction work with an average stress of approximately 70 kPa for the surface portion (residual soil) and greater than 150 kPa for the weathered rock portions. The estimated geotechnical parameters provided values that were an exact match with the numerical analyses. Thus, given the analyses and load transfer method, the piling lengths can be reduced, which will facilitate the optimisation of the geotechnical design.
Foundation piling; rock embedding; load test; three-dimensional numerical analysis
