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Matematično modeliranje drobirskih tokov in oblikovanja hudourniških vršajev
Kaltak, Sandi (Author), Mikoš, Matjaž (Mentor) More about this mentor... This link opens in a new window, Sodnik, Jošt (Co-mentor)

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Abstract
Matematično modeliranje drobirskih tokov je v Sloveniji postalo pomembnejše šele po letu 2000, ko je drobirski tok v Logu pod Mangartom terjal sedem življenj ter opustošil del vasi, sanacija posledic je stala več kot 15 milijonov EUR. S pomočjo računalniških programov za matematično modeliranje je mogoče izdelovati karte nevarnosti kot tudi načrtovati preventivne ukrepe v naravi z namenom, da bi lahko v prihodnosti omilili oziroma zmanjšali posledice takšnih dogodkov. V magistrski nalogi je v prvem delu opisan računalniški program RAMMS (angl. Rapid mass movement) za modeliranje drobirskih tokov, razvit na inštitutu Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) v Švici. Opisano in predstavljeno je njegovo delovanje, kot tudi postopek in način njegove uporabe pri modeliranju. S pomočjo normaliziranega kazalnika občutljivosti je narejena občutljivostna analiza programa. Analiziran je vpliv šestih izbranih modelnih vhodnih parametrov. Ker program RAMMS uporablja dvoparametrsko Voelmy-jevo strižno metodo za opis reologije drobirskega toka, je tema dvema parametroma v analizi posvečena posebna pozornost. V drugem delu naloge je izdelan in umerjen matematični model drobirskega toka v Logu pod Mangartom iz leta 2000. Rezultati so primerjani s predhodnimi modelnimi izračuni, ki so bili izvedeni s strani drugih avtorjev s programom PCFLOW2D. Drobirski tokovi se zaradi svojih reoloških lastnosti zaustavijo ob prehodu na teren z manjšim padcem in ob tem oblikujejo tipične morfološke oblike, ki jih imenujemo vršaji. Taki drobirski vršaji so praviloma strmejši od naplavinskih hudourniških vršajev. Podatek o naklonu vršajev je zato pomemben pri izdelavi kart nevarnosti pred drobirskimi tokovi. Z namenom boljšega razumevanja kako program RAMMS simulira oblikovanje drobirskih vršajev, je v tretjem delu naloge izbran vhodni parameter, za katerega iz občutljivostne analize sledi, da ima največji vpliv na zaustavitev drobirskega toka. Nato je za različne vrednosti tega parametra s pomočjo normaliziranega kazalnika občutljivosti narejena analiza vpliva tega parametra na oblikovanje naklona vršajev. Simulirani nakloni vršajev na testnem območju so pokazali veliko podobnost z izmerjenimi nakloni vršajev na realnih območjih v naravi, za katere so izbrani avtorji umerili v RAMMSu zgodovinske dogodke drobirskih tokov.

Language:Slovenian
Keywords:Matematično modeliranje, naravne nesreče, drobir, drobirski tok, RAMMS, vhodni parameter, občutljivostna analiza, normaliziran kazalnik občutljivosti, Log pod Mangartom, umerjanje, reologija, vršaj, hudourniški vršaj, drobirski vršaj
Work type:Master's thesis/paper (mb22)
Organization:FGG - Faculty of Civil and Geodetic Engineering
Year:2018
Views:100
Downloads:89
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Secondary language

Language:English
Title:Mathematical modeling of debris flows and formation of torrential fans
Abstract:
The modelling of debris flows was given more attention in Slovenia after the catastrophic event that occured in the village of Log pod Mangartom in November 2000 and that caused large economic damage (more than 15 milion EUR) and claimed seven human lives. With the help of computer programs for mathematical modelling of debris flows, hazard mapping of debris-flow prone areas can be carried our in order to mitigate and reduce the impact of these events. This Master’s thesis starts with an overview of the numerical debris-flow simulation model named RAMMS (Rapid mass movement) that was developed by the Swiss Federal Institute for Forest, Snow and Landscape Research WSL. RAMMS model is described and presented and the debris flow module is introduced. The work proceeds with a sensitivity analysis of the input parameters and sensitivity is evaluated using NSI (Normalized Sensitivity Index). Because RAMMS uses a Voellmy-fluid friction model that divides the frictional resistance into two parts, special emphasis is given to the sensitivity analysis and to the understing of the role of these two parameters on the RAMMS model results. In the second part, the thesis focuses on calibration of the RAMMS model for the 2000 debris flow event in the Log pod Mangartom.and the model results are compared to the model results calculated by the program PCFLOW2D. Debris flows stop due to their rheological properties in large and flat valleys where they form tipical morphological features named fans. Debris fans are generally steeper than the fans formed by torrential processes. Therefore, fan slopes are used as an indicator of possible debris flow occurrence in the debris-flow hazard mapping. Therefore, the third part of the thesis focuses on a sensitivity analysis of one selected Voellmy parameter that has the largest impact on model results. Further, sensitivity analysis is used to evaluate impact of different values of the parameter µ on the fan slopes. The results indicate that fan slopes simulated by the RAMMS have similar values as those that can be found in the natural environment and for which some authors have calibrated historical debris flow events using RAMMS.

Keywords:Mathematical modeling, natural dissasters, debris, debris's flow, RAMMS, input paramethers, sensitivity analysis, normalized sensitivity index, Log pod Mangartom, calibration, reology, fan, torrential fan, debris flow fan, fan formation

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