3D Finite Element analysis of accelerated pavement test results from New Zealand’s CAPTIF Facility

Abstract

A nonlinear elastic model for unbound granular materials that was developed from the results of multi-stage Repeated Load Triaxial (RLT) Tests is described in this paper. The model was implemented in the 3-D FE-program FALTFEM. To check the validity of the model, comparisons were made with the results from accelerated pavement tests at Transit New Zealand’s CAPTIF Facility. The stresses and elastic strains within the test pavement at different depths were measured. A comparison was carried out to assess the accuracy of the elastic model by comparing the results of calculated elastic responses from the model using the nonlinear elastic DRESDEN Model and elastic solutions against the measured values. In addition an empirical approach was formulated and calibrated to determine basecourse plastic strain rate using data from RLT and CAPTIF tests of two different materials. From results of laboratory tests a good correlation
was found to exist between the elastic strain rate and the plastic strain rate as long as the shear stresses within the basecourse material are sufficiently small. However, by comparing the elastic/plastic relationship from RLT tests and the elastic/plastic relationship from CAPTIF tests differences could be observed. Shift factors were determined for the materials investigated, to predict the plastic strain rate in the field from RLT test results.