It is well known that any asphalt roadway being a transport infrastructure exposed to environmental conditions is therefore subject to two load sources of different nature, namely thermal and mechanical loads. These types of load lead to several distresses such as cracking and rutting mainly but also the common potholes and corrugation phenomena. Obviously, the combination of these two different actions leads to an aggravation of the performance of the road pavement. Since from the environmental point of view the temperatures cannot be changed the only parameter that can be managed intelligently is traffic loading. In this thesis the impact due to the introduction of the platooning system on pavement performance was studied. To do this, evaluating the fatigue cracking and rutting prediction, a comparison was made considering two cases of traffic configuration (uncontrolled traffic and platooning case) in two opposite temperature scenarios (warm and cold). In order to study this aspect, the Abaqus CAE software was used, through which it was possible to develop a coupled thermo-mechanical model. Furthermore, a fully coupled approach was chosen. It was chosen to study the behavior of a multilayer asphalt pavement whose properties (geometric, thermal and mechanical) have been defined in accordance with the standards and the research carried out in the most recent past. It should be noted that the two upper layers were considered as viscoelastic while the other two were assumed as elastic. As mentioned, reference was made to the warm and cold scenario in which the surface temperatures applied are the highest and lowest measured on real asphalt pavements by two studies, respectively. As regards to the mechanical loading, three types of vehicles (passenger cars, light and heavy trucks) were chosen considering uncontrolled traffic and platooning situations for both temperature scenarios. Analyses were carried out considering all possible variations (temperatures, vehicles, traffic distributions) with 200 s of total analysis time. These simulations were performed with a time step of 0.01 s while the outputs were extracted every 1 s. In addition, a different number of load cycles have been generated depending on the type of vehicle (wheelbase) and each cycle consists of ten vehicles of the same type that pass with a constant speed of 50 km/h. The assessment of both fatigue cracking and rutting prediction was made using the equations provided by the standards in the literature. By comparing the results obtained, it was found that the introduction of platooning results in a beneficial effect with different rates depending on the vehicle considered. Since in this study the purpose was not to optimize the road capacity in terms of traffic but the evaluation of the pavement performance these results make sense. In addition, the improvement percentage is greater the lower the axle load and the cycle time discrepancy. Considering the two temperature scenarios, it turns out that the cold scenario is preferable as it generates a lower thermal gradient than the warm case.
Effetto del plotone di veicoli sulle prestazioni della pavimentazione mediante un modello termo-meccanico accoppiato. È ben noto che qualsiasi strada asfaltata essendo un'infrastruttura di trasporto esposta a condizioni ambientali è quindi soggetta a due fonti di carico di diversa natura, vale a dire carichi termici e meccanici. Questi tipi di carico portano a diversi problemi come il cracking (fessurazione) e il rutting (deformazione permanente) principalmente, ma anche le comuni buche e i fenomeni di corrugazione. Ovviamente, la combinazione di queste due diverse azioni porta ad un aggravamento delle prestazioni della pavimentazione stradale. Siccome dal punto di vista ambientale le temperature non possono essere modificate, l'unico parametro che può essere gestito in modo intelligente è il carico del traffico. In questa tesi è stato studiato l'impatto dovuto all'introduzione del sistema di platooning sulle prestazioni della pavimentazione. Per fare questo, valutando il cracking a fatica e la previsione del rutting, è stato effettuato un confronto considerando due casi di configurazione di traffico (traffico incontrollato e caso di plotooning) in due scenari di temperatura opposti (caldo e freddo). Per studiare questo aspetto, è stato utilizzato il software CAE di Abaqus, attraverso il quale è stato possibile sviluppare un modello termo-meccanico accoppiato. Inoltre, è stato scelto un approccio completamente accoppiato. È stato scelto per studiare il comportamento di una pavimentazione in asfalto multistrato le cui proprietà (geometriche, termiche e meccaniche) sono state definite in conformità con gli standard e le ricerche condotte nel passato più recente. Va notato che i due strati superiori sono stati considerati viscoelastici mentre gli altri due sono stati considerati elastici. Come accennato, è stato fatto riferimento allo scenario caldo e freddo in cui le temperature superficiali applicate sono rispettivamente le più alte e le più basse misurate da due studi su pavimentazioni reali in asfalto. Per quanto riguarda il carico meccanico, sono stati scelti tre tipi di veicoli (autovetture, camion leggeri e pesanti) tenendo conto delle situazioni di traffico incontrollato e platooning per entrambi gli scenari di temperatura. Le analisi sono state effettuate considerando tutte le possibili variazioni (temperature, veicoli, distribuzioni di traffico) con 200 s di tempo totale di analisi. Queste simulazioni sono state eseguite con uno step di 0.01 s mentre gli output sono stati estratti ogni 1 s. In aggiunta, è stato generato un numero diverso di cicli di carico a seconda del tipo di veicolo (interasse) e ogni ciclo è costituito da dieci veicoli dello stesso tipo che transitano a una velocità costante di 50 km/h. La valutazione sia del cracking a fatica che della previsione del rutting è stata effettuata usando le equazioni fornite dagli standard in letteratura. Confrontando i risultati ottenuti, si è riscontrato che l'introduzione del platooning comporta un effetto benefico con tassi diversi a seconda del veicolo considerato. Poiché in questo studio lo scopo non era ottimizzare la capacità della strada in termini di traffico, ma la valutazione delle prestazioni della pavimentazione questi risultati hanno senso. Inoltre, la percentuale di miglioramento è tanto maggiore quanto minore è il carico sull'asse e la discrepanza del tempo di ciclo. Considerando i due scenari di temperatura, risulta che lo scenario freddo è preferibile in quanto genera un gradiente termico inferiore rispetto al caso caldo.
Effect of vehicle platooning on pavement performance using a coupled thermo-mechanical model
FORNI, DAVIDE
2018/2019
Abstract
It is well known that any asphalt roadway being a transport infrastructure exposed to environmental conditions is therefore subject to two load sources of different nature, namely thermal and mechanical loads. These types of load lead to several distresses such as cracking and rutting mainly but also the common potholes and corrugation phenomena. Obviously, the combination of these two different actions leads to an aggravation of the performance of the road pavement. Since from the environmental point of view the temperatures cannot be changed the only parameter that can be managed intelligently is traffic loading. In this thesis the impact due to the introduction of the platooning system on pavement performance was studied. To do this, evaluating the fatigue cracking and rutting prediction, a comparison was made considering two cases of traffic configuration (uncontrolled traffic and platooning case) in two opposite temperature scenarios (warm and cold). In order to study this aspect, the Abaqus CAE software was used, through which it was possible to develop a coupled thermo-mechanical model. Furthermore, a fully coupled approach was chosen. It was chosen to study the behavior of a multilayer asphalt pavement whose properties (geometric, thermal and mechanical) have been defined in accordance with the standards and the research carried out in the most recent past. It should be noted that the two upper layers were considered as viscoelastic while the other two were assumed as elastic. As mentioned, reference was made to the warm and cold scenario in which the surface temperatures applied are the highest and lowest measured on real asphalt pavements by two studies, respectively. As regards to the mechanical loading, three types of vehicles (passenger cars, light and heavy trucks) were chosen considering uncontrolled traffic and platooning situations for both temperature scenarios. Analyses were carried out considering all possible variations (temperatures, vehicles, traffic distributions) with 200 s of total analysis time. These simulations were performed with a time step of 0.01 s while the outputs were extracted every 1 s. In addition, a different number of load cycles have been generated depending on the type of vehicle (wheelbase) and each cycle consists of ten vehicles of the same type that pass with a constant speed of 50 km/h. The assessment of both fatigue cracking and rutting prediction was made using the equations provided by the standards in the literature. By comparing the results obtained, it was found that the introduction of platooning results in a beneficial effect with different rates depending on the vehicle considered. Since in this study the purpose was not to optimize the road capacity in terms of traffic but the evaluation of the pavement performance these results make sense. In addition, the improvement percentage is greater the lower the axle load and the cycle time discrepancy. Considering the two temperature scenarios, it turns out that the cold scenario is preferable as it generates a lower thermal gradient than the warm case.È consentito all'utente scaricare e condividere i documenti disponibili a testo pieno in UNITESI UNIPV nel rispetto della licenza Creative Commons del tipo CC BY NC ND.
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https://hdl.handle.net/20.500.14239/25246