Technical information

1-4
includes only the tasks required to achieve the aforementioned study objectives. The
scope and purpose of each task are described hereafter.
Task 1 consists of careful study, systematic documentation and presentation of
pertinent test data from both the APT and NCAT experiments. The aim here is to
familiarize the reader with relevant details of the work done. It is mostly descriptive in
nature with limited pre-processing of the data. The raw test results are contained in
Appendix A.
Task 2 includes the identification of response data suitable for mechanistic
analysis; the aim here is to identify a subset of the available data that is most suitable
and sufficient for accomplishing the main study objective.
Task 3 contains the development and calibration of a mechanistic pavement
model based on APT data only. This task is the central element of the entire
methodology. As a basic case, the mechanistic ‘engine’ of the MEPDG is applied, i.e.,
layered elastic theory (LET) with isotropic material properties. Also considered are two
more advanced models, namely: LET with transversely isotropic material properties and
layered viscoelastic theory (LVT) with linear isotropic material properties. In each case
the numerical values of the model parameters are obtained from inverse analysis by
simulating the APT experiment and matching the measured responses.
In Task 4 the capabilities of the APT model are enhanced. For this purpose an
analysis scheme is developed by which the derived material properties obtained in Task
3 are adjusted in order for them to apply to other loading configurations, other loading
speeds, and different environmental conditions. These adjustments are based primarily
on the analysis of laboratory test data.
Finally, Task 5 deals with model validation using NCAT results. For this
purpose the loading and environment at NCAT are simulated and the forecastability of
the ‘enhanced’ model (Task 4) is assessed by comparison with NCAT measurements.
1.4 STRUCTURE OF THE REPORT
Chapters 2 and 3 address tasks 1 and 2. Chapter 2 is mainly narrative with minimal
interpretation; containing relevant information from the NCAT experiment such as
description of the facility loading conditions, composition and instrumentation of the