Procesi pri transportu kohezivnih sedimentov : diplomska naloga

Pečovnik, Urška (author), Žagar, Dušan (mentor)

Pri procesih transporta, kot sta usedanje in privzdigovanje, obstajajo med kohezivnimi in nekohezivnimi sedimenti bistvene razlike. Obstoječi model PCFLOW3D ima v sedimentacijskem modulu vgrajene enačbe za nekohezivne sedimente, zato smo predpostavili, da na območjih kjer so sedimenti kohezivni, ne daje pravilnih rezultatov. Poiskali smo enačbe za račun usedanja, privzdigovanja in transporta kohezivnih sedimentov in jih primerjali z že vgrajenimi enačbami v modelu. Poiskali smo parametre, ki jih potrebujemo za račun procesov transporta kohezivnih sedimentov in izpostavili bistvene razlike med kohezivnimi in nekohezivnimi sedimenti. V diplomski nalogi smo s preprostimi izračuni v Excelu pokazali rezultate enačb vgrajenih v model PCFLOW3D in rezultate dobljene z enačbami za kohezivne sedimente. Rezultate smo primerjali in ugotovili, da model na območju kohezivnih sedimentov znatno podceni kritične strižne napetosti. Naloga predstavlja prispevek k boljšemu razumevanju razlik med procesi pri kohezivnih in nekohezivnih sedmentih, pokazali smo tudi, katere spremembe so v modelu PCFLOW3D potrebne, da ga bo mogoče uporabljati kot orodje za račun transporta plavin tudi na območjih kohezivnih sedimentov.

• Language: Slovenian
• Keywords: gradbeništvo, diplomska naloga, UNI, B-VOI, transport plavin, kohezivni sedimenti, kritična pridnena strižna napetost, model PCFLOW3D
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: U. Pečovnik
• Year: 2014
• Number of pages: XIII, 52 str.
• PID: 20.500.12556/RUL-32385
• UDC: 004:532.5(497.4)(043.2)
• COBISS.SI-ID: 6782817
• Publication date in RUL: 10.07.2015

Secondary language

• Language: English
• Title: Cohesive sediment transport processes

Abstract

In the sediment transport processes, settling and resuspension, there are significant differences between cohesive and non cohesive sediments. In the sediment transport module of the existing model PCFLOW3D only equations for non cohesive sediments are included. Therefore, we assumed that the model does not perform correctly in areas with cohesive sediments. We identified the equations for the cohesive sediment settling, resuspending and transport, and compared them with the equations included in the PCFLOW3D model. Furthermore, the parameters needed for simulations of these transport processes were identified and the significant differences between cohesive and non cohesive sediment were emphasised. We performed simple calculations in order to show the results of both the equations of the PCFLOW3D model and the equations for cohesive sediments, as well as to compare the results to each other. We detected significant discrepancies and concluded that the PCFLOW3D model significantly underestimates the critical bed-shear stress in the areas with cohesive sediments. The thesis is a contribution to better understanding of different transport processes in cohesive and non cohesive sediments. We also proposed adequate equations for upgrading the PCFLOW3D model in order to be used in cohesive sediment areas.

• Keywords: sediment transport, cohesive sediment, critical bed-shear stress, PCFLOW3D model