A general overview of conventional and some advanced numerical models used in practice has been given in Chapter 9, Section 9.4. Therefore, tests needed for the parameters of these models will now be presented.
• Resilient behaviour models
о Routine pavement design model: in practice much routine pavement design is carried out as catalogue — based design. The pavement is considered as a multi-layered elastic system with constant stiffness parameters in each layer.
о Advanced pavement models: RLT tests are required with variable confining pressure (CEN standard EN 13286-7 (2004)), they correspond to strain stabilization. Parameters are determined with curve fitting by the least squares method applied to the equations of the model and to RLT tests results in the stress — elastic strain planes (p, ev) and (q, eq). Both phenomenological models which describe behaviour from an observational standpoint (such as the k—6 and “Universal” Models) as well as theoretically-derived models (such as the Boyce and modified Boyce model) require this kind of testing. The more complex models require VCP test procedures (see Section 10.2.1, above).
• Permanent deformations models
о Analytical models: they require 3 monotonic triaxial tests for the rupture parameters and 3 VCP tests (q /p = 1, 2 and 3 for example) for the plasticity parameters. Curve fitting can be used with the least squares method applied to VCP tests results and to the analytical equation of the model
(evertical f(N)) in the plane (N, e^cal).
о Plasticity theory based models
• Bonaquist and Desai models
— Elastic behaviour: the parameters require RLT tests (q /p = 3) at various confining pressures (AASHTO T307-99 (2000)).
— Monotonic plasticity parameters: 3 monotonic triaxial tests till rupture for the rupture characteristics and hardening parameters.
— Approximate accelerated analysis: 1 RLT test with one stage at (q /P = 3) is required.
• Chazallon and Hornych model
— Elastic behaviour: RLT tests are required with variable confining pressure (CEN standard EN 13286-7 (2004)), they correspond to strain stabilization.
— Monotonic plasticity parameters: 1 oedometric test, and 3 triaxial tests till rupture are required.
— Cyclic plasticity parameters: 1 RLT test with one stage is required
(q /p = 2).
о Elasto-visco-plastic equivalent models
• Suiker elasto-visco-plastic model
— Elastic behaviour: these parameters are required for the initial state of the material. They require at least 2 monotonic triaxial tests at two different confining pressures when 100 cycles have been performed (q / p = 3).
— Monotonic plasticity parameters: they are required for the initial state of the material: 3 monotonic triaxial tests are required.
— Cyclic plasticity parameters: RLT tests (q/p = 3) are required.
о Mayoraz visco-plastic model
— Plasticity parameters require 3 triaxial tests till rupture and a RLT test
(q/p = 3).
о Shakedown models
• Perfectly plastic models
— Elasticity parameters: RLT tests (CEN standard EN 13286-7 (2004)) are required with variable confining pressure till stabilization.
— Plasticity parameters: 3 triaxial monotonic tests till rupture are required.
• Kinematic hardening models
— Elasticity parameters: RLT tests (CEN standard EN 13286-7 (2004)) are required with variable confining pressure till stabilization.
— Plasticity parameters: 3 triaxial monotonic tests till rupture are required for rupture parameters and 3 VCP tests (q /p = 1,2 and 3 for example) with 3 stages for each stress path.
