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Deterioration of asphalt pavements due to fatigue cracking is one of the most common highway pavement failure types. If the fatigue cracks are allowed to develop and grow, the driving comfort and safety, i.e., serviceability of the pavement, decreases. Pavement fatigue behaviour is not a straightforward mechanism and involves many factors and effects, thus computational methods are developed in order to help understand how the pavement works. This paper explores the accuracy and applicability of a less computational resource demanding procedure that uses transient material mechanical behaviour to model the long-term behaviour of a pavement structure. First, the mechanical and fatigue properties of asphalt were determined at the laboratory. Then a four-layer finite-element model was created using Ansys software. Two different models – with and without infinity elements – and two different fatigue simulation procedures – full and simplified – were considered. Material parameters were obtained by the laboratory tests and material properties degraded over time. Cyclic surface loading was applied to simulate the passing of a truck – 6 million fatigue cycles were simulated.

This study presents the importance of using advanced constitutive soil models in numerical modelling as a daily geotechnical practice. Back-calculated stiffness from observations of the soil deformations in-situ very often are greater than those used for the geotechnical design. Design is often too conservative, because of insufficient soil investigation data, in terms of applied material models and simplification in analytical or numerical design [2–4,10,14] . Hence, there are highlighted advanced soil testing techniques and consecutive soil material models in this study, which could help to estimate pile settlements in PLAXIS 3D AE02 numerical code. Pile loading test is simulated for different pile diameters and interface constrains at the specific site, where residential building is designed on piles. Bender element tests were conducted at laboratory for subglacial till as the end-bearing soil layer for the project, and Hardening Soil Small (HSSmall) soil material model applied in the numerical analysis. The presented approach gives initial pile bearing capacity estimation for different pile diameters and interface constrains, so designer can decide the most technically and economically substantiation technology. In-situ pile loading test data essentially would help to calibrate initial model for the designed pile, finally adjusting the geotechnical design.

Modification and stabilization of road structure unbound layers has extensively been studied both at laboratory and field for decades. It has become of economical, technical and environmental interest, because it allows to use or recycle existing bound and unbound material modifying and stabilizing with binder. However, there is typically not sufficient information available on the design parameters of the stabilized materials. This research accumulates information about the procedures and design approaches for pavement structures, where stabilized Reclaimed Asphalt Pavement (RAP) road base layers are used. Pavement of four road sections on the State Main Road A7 with equally designed structures were studied and equivalent modulus of elasticity Eeq was back-calculated based on Falling Weight Deflectometer (FWD) measurements. The modulus of elasticity for cement stabilized RAP were determined at laboratory and equivalent deformation modulus of elasticity Eeq on pavement surface was calculated in accordance to the National Pavement Design Guide. Furthermore, FWD was validated with Finite Element Method (FEM) in PLAXIS 3D AE02.