Elastic Nonlinear Finite Element Analysis of a Flexible Pavement Subjected to Varying Falling Weight Deflectometer Loads

Abstract

A nonlinear finite element method (FEM) model has been developed to model thin-surfaced, unbound granular pavements. The FEM model incorporates a nonlinear anisotropic material model for the granular material and a nonlinear material model for the subgrade. The coefficients for the material models were determined from laboratory repeated load triaxial tests. A test pavement at the Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF) was instrumented with an inductive coil soil strain system to measure vertical compressive strains and pressure cells to measure the vertical compressive stresses. The test pavement was subjected to loading by a falling weight deflectometer (FWD) device at four different load levels. The initial FEM model configuration was undertaken at one load level using the surface deflection measurements from the FWD; however, there were significant differences between the computed and measured stress and strain values. The scalar coefficients for the granular and subgrade materials were adjusted so that the measured and computed stress and strain values matched within a reasonable tolerance (10%). After the calibration process was finished, it was found that the computed and measured surface deflections also matched. The model was rerun with the three remaining load cases; the computed and measured stress, strain, and surface deflection values were in close agreement. The range of computed stiffness values varied with both the pavement and load level. The results from this analysis showed the need to use a full nonlinear model to obtain realistic results when FWD data are modeled.

Δυναμική Απόκριση Τρισδιάστατων Εύκαμπτων Οδοστρωμάτων Σε Κινούμενα Οχήματα Με Μέθοδο Πεπερασμένων Στοιχείων

“…καμία εργασία δεν θεωρεί όλες τις παραμέτρους που επηρεάζουν την ακρίβεια και αξιοπιστία των αποτελεσμάτων απόκρισης και ii) σε πολλές περιπτώσεις δεν υπάρχει γενική συμφωνία μεταξύ των συγγραφέων για το είδος και το μέγεθος της επίδρασης που έχει κάθε παράμετρος επί της απόκρισης, όπως, π.χ., η επίδραση του είδους των συνοριακών συνθηκών, ή η φύση της φόρτισης. Duncan et al (1968), Taylor (1971), Elliott and Thompson (1985), Harichandran et al (1990), Balay and Kabre (1996), Guezouli et al (1996), Van Schelt et al (1996), Gomes Correia and de Almeida (1998), Helwany et al (1998), Hadi and Bodhinayake (2003), Kim (2007), Kim et al (2008), Steven et al (2007) Zaghloul et al (1994), όπου το φορτίο ήταν δυναμικό αλλά στάσιμο.…”