Numerical modelling of performance and failure criteria for surfacing seals

Gerber, Johan Andries Kritzinger (2016-03)

Thesis (DEng)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: Finite element modelling of complex structures such as bituminous surfacing seals has become a viable practice to obtain insight into the structure's response behaviour. These responses are difficult, if not impossible to measure in the field and are used to explain seal failure mechanisms. The three major failure mechanisms include: surface ravelling, surface cracking and surface texture loss. Surface cracking and ravelling contributes to surface deterioration which manifests permeability, allowing vertical moisture ingress into the underlying pavement structure. Moisture ingress has a detrimental eff ect on the pavement surface resulting in potholing, while surface texture loss reduces skid resistance in wet conditions. Since existing damage models are outdated and largely empirical, f inite element modelling of seals can be used in the development of improved damage models for seals. Conducting fi nite element simulations on single, double and cape seals, established the groundwork from which a seal response model was developed for each seal type and failure mechanism. Applying laboratory developed damage functions to the response model, quantifi ed each response type in terms of load repetitions to failure which was validated with empirical and fi eld data. The outcome of this study is a verifi ed primary seal response model that is capable of providing a failure response, based on actual seal design variables. The primary seal response model provides information to improve existing deterioration models for seals, such as the Highway Development and Management (HDM-4) models. It further facilitates the selection of the most appropriate seal for specific environmental and traffic conditions.

AFRIKAANSE OPSOMMING: Eindige-element modellering van ingewikkelde strukture soos bitumenplaveiselseëls is 'n bruikbare metode vir waarnemings en insig van die struktuur se vertoongedrag. Hierdie vertoongedrag is moeilik, al dan nie onmoontlik om in die veld te meet en word gebruik om die seël se falingsmeganismes te verduidelik. Die drie hoof falingsmeganismes sluit in: klipverlies, ryoppervlak-krake en tekstuurverlies van die ryoppervlak. Ryoppervlak-krake en klipverlies dra by tot ryoppervlak agteruitgang, wat lui tot vog deurlaatbaarheid en vog indringing op die kroonlaag. Vog indringing het 'n nadelige effek op die ryoppervlak en lui tot die vorming van slaggate, terwyl ryoppervlak tekstuurverlies die glyweerstand verlaag in nat toestande. Omdat bestaande skade modelle verouderd en hoofsaaklik empiries is, kan eindige-element modellering van seëls gebruik word in die ontwikkeling en verbetering van skade modelle vir seëls. Eindige element simulasies van enkel, dubbel en kaapse-seëls het die grondslag gevorm waarvan 'n seël vertoongedragsmodel ontwikkel is vir elke seël tipe en falingsmeganisme. Toepassing van laboratorium ontwikkelde oordragfunksies op die vertoongedragsmodel, het gelui tot kwantifisering van elke vertoongedragstipe na lasherhalings tot faling en is bekragtig met veld en empiriese data. Die uiteinde van hierdie studie 'n is verifieerde primêre seël vertoongedragsmodel wat seël vertoongedrag verskaf, gebaseer op werklike seëlontwerp veranderlikes. Die primêre seël vertoongedragsmodel verskaf inligting wat gebruik kan word om verbeteringe mee te bring aan bestaande seël agteruitgangsmodelle, soos die Highway Development and Management (HDM-4) modelle. Dit vergemak ook die besluitnemingsproses van die mees toepaslike seël vir 'n spesifieke klimaatstreek en verkeerstoestande.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98526
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