Hierarchical approach for fatigue cracking performance evaluation in asphalt pavements

In this paper, a hierarchical approach is proposed for the evaluation of fatigue cracking in asphalt concrete pavements considering three different levels of complexities in the representation of the material behaviour, design parameters characterization and the determination of the pavement response as well as damage computation. Based on the developed hierarchical approach, three damage computation levels are identified and proposed. The levels of fatigue damage analysis provides pavement engineers a variety of tools that can be used for pavement analysis depending on the availability of data, required level of prediction accuracy and computational power at their disposal. The hierarchical approach also provides a systematic approach for the understanding of the fundamental mechanisms of pavement deterioration, the elimination of the empiricism associated with pavement design today and the transition towards the use of sound principles of mechanics in pavement analysis and design

Probabilistic Study on the Geotechnical Behavior of Fiber Reinforced Soil

Expansive soils which are considered extremely problematic due to their potential to create swell and shrinkage-related distresses. In order to satisfy the geotechnical requirements, these soils are fiber reinforced to sustain dynamic loads as a subgrade material. Polypropylene fiber materials when amended with soil medium, have proven functionality in the long run. Usually, a binder is required to ensure proper bonding between discrete/random fiber elements and the clay particulates. In the current study, lime is a proposed binder and its dosage is fixed at 6% satisfying initial lime consumption and optimum lime requirements. Two types of fiber materials (Fiber Cast® and Fiber Mesh®) at varying dosages (0.2, 0.4, and 0.6% by weight of soil) and having different lengths (6 and 12 mm) are considered for the present study and its inclusion effect on the hydraulic conductivity, unconfined compression strength behavior and California bearing ratio behavior has been studied. The focus of this paper is in determining the optimum fiber reinforcement parameters (fiber type, length, dosage, etc.) for the stabilization of selected expansive Al-Ghat soil. Probabilistic analysis has been performed to correlate the targeted properties with aspect parameters (i.e., dosage and length) for fiber-reinforced soil. In addition to this, reliability analysis has been performed to examine the applicability of this fiber-reinforced soil in municipal solid waste (MSW) landfills for waste containment. The probabilistic analysis revealed that both aspect parameters play a crucial role in fiber-reinforced soils. Further, it is concluded that the target reliability approach (TRA) gives a valuable insight with regards to choosing optimum aspect parameters for effective soil stabilization practice