Projekt BVFF - publicerade   BVFF nummer:  2014-033 Projekttitel  Mechanics-based design framework: integration, model extension and implementation Projektledare/Kontaktperson  Björn Birgisson/Denis Jelagin Telefon  +46 8 790 8698 Utförarorganisation  KTH Medutförare  - Bakgrund  Current state-of-practice pavement design procedures rely on empirical relationships to predict the pavement degradation. As a result the state-of-practice design methods cannot describe the progress of pavement degradation in the field as well as pavement economic life and are not able to capture the effect of using unconventional and novel materials in road construction. In order to evaluate the functional performance of a pavement over time and it’s remaining life it is necessary to develop a mechanics-based design procedure based on fundamental measurable material properties. In order to address this need a new Mechanics-based pavement design procedure is being developed at Highway and Railway Engineering Division, KTH under the project “AL90B2008:9074. Upphandling på Funktion-Kriterier och Mätmetoder”. The first generation of the design procedure has been implemented and evaluated with the PMS-objekt in 2011. Presently, a second generation of the design code is being calibrated at KTH and the work is expected to be finalized in the fall 2013. The procedure in its present shape is capable of optimizing asphalt layer thickness with respect to cracking initiation and propagation. Two different stress analysis strategies are incorporated into the code; the crack initiation conditions are evaluated based on the layered elastic analysis, and once the crack is initiated its propagation is evaluated based on the BEM model. Due to presence of explicit damage and healing models, the framework allows for monitoring of damage evolution and crack propagation with time. The proposed projects deals with the further extension and evaluation of the Mechanics-based design procedure developed at KTH. In particular, a unified cracking and rutting degradation model will be developed and incorporated into the design framework. Furthermore, the morphological framework for the performance evaluation of unbound materials developed within the “AL90A2007:13404. Obundna lager (dimensioneringsmetodik för spårbildning) CDU” project will be extended further and incorporated into the design code. This will provide a tool to design unbound layers in road structure based on their fundamental properties as well as to predict the effect moisture has on the unbound layers performance. The results obtained under the project “AL90B2008:9632. Utveckling av riktlinjer för bedömning av tung trafiks skadeverkan på vägöverbyggnad” will also be incorporated into the design system to capture the effect the dynamic vehicle-road interaction has on the loads induced on pavement by the traffic. In order to further evaluate the design procedure developed the system will be used to monitor the existing PPP projects in Sweden, the particular sections will be identified in collaboration with major Swedish contraction. Swedish pavement sections with known performance will be identified and used for the design system evaluation. Sammanfattning  The proposed project is focused on evaluation and validation of the Mechanics-based design procedure developed at KTH. As a result of the project, the finalized design method will be implemented as open platform software tool and further evaluation will be performed in collaboration with the division’s industrial partners as well as through the extensive network of industrial/international partners of the Road2Science research centre at KTH. This will facilitate faster implementation of the results achieved in the project in engineering practice. Furthermore, several models presently under development at KTH will be finalized and incorporated into the design method. The work done under the project will facilitate the use of the Mechanics-based design procedure developed at KTH in pavement structural design practice. The availability of explicit models that account for material, structural and environmental factors known to affect pavement performance will lead to a better understanding of the mechanisms involved and the most important factors that need to be controlled for effective mitigation of early failure. Förväntat resultat  The main outcome of the project will be implementation of the third generation of the pavement design procedure incorporating the following new developed/extended models: - Unified cracking/rutting model - Surface roughness evolution model - Model to estimate dynamic loads from vehicles - Unbound layers performance model with moisture distribution and suction prediction submodels. In order to ensure that the new Mechanics-based procedure is implemented in practice, the extensive calibration and validation of the design method will be performed. The dataset of Swedish road sections will be formed in collaboration with Trafikverket, VTI as well as major contractors and the design procedure will be evaluated extensively for the Swedish conditions. As a result of the project, the finalized design method will be implemented as open platform software tool and further evaluation will be performed in collaboration with the division’s industrial partners as well as through the extensive network of industrial/international partners of the Road2Science research centre at KTH. This will facilitate faster implementation of the results achieved in the project in engineering practice. Plan för resultatspridning och implementering  In order to ensure that the results of the project are communicated to the research community and to the users, the following steps will be taken: - The new open platform implementation of the design procedure will be made available to the division’s partners and will act as a main vehicle for the communication of the research results achieved in the project. - Research progress will be bi-weekly presented at the Highway and Railway Engineering Division seminars, attended both by researchers and industry representatives; - A user reference group will be formed at the start of the project. The reference group will consist of representatives of the following authorities/companies: Trafikverket (Klas Hermelin, Tomas Winnerholt), Skanska (Ulf Håkansson), NCC (Staffan Hintze). Three times a year, a detailed presentation will be given to this reference group. - Results of the project will be published in several scientific papers and summarized in a PhD-thesis. - Results will be as well presented in national and international conferences. Tidsramar  The project is expected to take 4 years. Starting middle of 2014.