Toplotna analiza velikih ločno-težnostnih betonskih pregrad : doktorska disertacija

Žvanut, Pavel (author), Turk, Goran (mentor), Kryžanowski, Andrej (co-mentor)

V doktorski disertaciji je predstavljen algoritem za modeliranje prehoda toplote skozi betonsko pregrado, ob upoštevanju časovno spremenljivih robnih pogojev na gorvodni in dolvodni strani pregrade (gladina vode v akumulaciji, prelivanje vode čez krono pregrade, osončenost in osenčenost), s katerim so bila določena temperaturna stanja pregrade. Za določitev vpliva osenčenosti je bila uporabljena nova metoda in sicer na podlagi meritev s terestričnim laserskim skenerjem ter uporabe dveh računalniških programov, izdelanih v programskih okoljih Mathematica in MATLAB, ki za izbrano opazovalno točko določita obris terena ter položaj Sonca in osončenost v času. Obravnavana je bila velika ločno-težnostna betonska pregrada Moste, ki se nahaja na severozahodu Slovenije, na kateri je bil julija 2013 vzpostavljen avtomatski sistem meritev temperatur betona in vode ter spremljanja vremenskih vplivov z mobilno vremensko postajo. Toplotne analize (1D in 2D) za nelinearno in nestacionarno prevajanje toplote v trdnih snoveh so bile izdelane z metodo končnih elementov s programom TeEx v MATLABu, ki je bil dopolnjen z izdelanima programoma za določitev vplivov konvekcije in osončenosti. Obravnavana so bila tri različna 15-dnevna obdobja (vplivi oblačnosti, prelivanja in gladine vode) ter letno obdobje, pri čemer so se rezultati toplotnih analiz zelo dobro ujemali z eksperimentalnimi rezultati meritev temperatur betona. Na osnovi rezultatov 2D toplotnih analiz so bila izdelana temperaturna polja pregrade tekom leta. Mehanske analize so bile izdelane z metodo končnih elementov s programom DIANA za 2D in 3D model pregrade, kjer se je ugotavljal vpliv spremembe hidrostatskega tlaka in temperaturne obtežbe na vodoravne pomike zgornjega dela pregrade. Rezultati mehanskih analiz so pokazali zelo dobro ujemanje z rezultati avtomatskih meritev vodoravnih pomikov z visečim grezilom. V sklopu toplotnih in mehanskih analiz so bile izdelane tudi analize nezanesljivosti rezultatov izračunov.

• Language: Slovenian
• Keywords: grajeno okolje, betonske pregrade, prehod toplote, modeliranje, konvekcija, osončenost, osenčenost, meritve temperature, ločno-težnostna betonska pregrada, pregrada Moste, mehanska analiza, analiza nezanesljivosti, gradbeništvo
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Publisher: [P. Žvanut]
• Year: 2017
• PID: 20.500.12556/RUL-99191
• UDC: 005.52:536:627.82(497.4Moste)(043)
• COBISS.SI-ID: 8118625
• Publication date in RUL: 08.01.2018

Licences

• License: CC BY-NC 4.0, Creative Commons Attribution-NonCommercial 4.0 International
• Link: http://creativecommons.org/licenses/by-nc/4.0/
• Description: A creative commons license that bans commercial use, but the users don’t have to license their derivative works on the same terms.
• Licensing start date: 08.01.2018

Secondary language

• Language: English
• Title: Thermal analysis of large arch-gravity concrete dams : doctoral thesis

Abstract

This doctoral dissertation presents an algorithm for modelling the heat transfer process in a concrete dam, taking into account the time-varying boundary conditions on the upstream and downstream sides of the dam (i.e. the water level of the reservoir, spillover, insolation, and shading) which affected the temperature conditions of the dam. In order to investigate the effect of shading, a new method was applied, which is based on terrestrial laser scanner measurements and the use of two computer programs which were designed within the computing environments Mathematica and MATLAB. Using this approach it was possible to determine, for any selected observation point, the contour of the terrain, the position of the Sun, and insolation over time. A large arch-gravity concrete dam was analysed, the so-called Moste Dam, which is located in north-west Slovenia, where an automated system for the measurement of concrete and water temperatures, and for the monitoring of meteorological effects using a mobile weather station, was installed in July 2013. Thermal analyses (1D and 2D) for non-linear and non-stationary heat conduction through solids were performed using the finite element method based program TeEx (written in MATLAB), which was complemented by two specially formulated programs for determining the effects of convection and insolation. Three different 15-day periods (with varying cloudiness, spillover, and water levels of the reservoir) were analysed, as well as a period of one year. It was found that the results of the performed analyses fitted in well with the experimentally determined concrete temperature measurements. Additionally, based on the results of the 2D thermal analyses, dam temperature fields corresponding to the complete year of measurements were elaborated. Stress-strain analyses were also performed, using the finite element method based computer program DIANA, for both the 2D and the 3D model of the dam, in order to investigate the effect of changes in (1) hydrostatic pressure and (2) thermal loading on the horizontal displacements of the upper part of the dam. The results of the stress-strain analyses showed very good agreement with the results of the automatic measurements of horizontal displacements that were obtained by using a hanging pendulum. As part of the thermal and stress-strain analyses, uncertainty analyses of the results of the calculations were also performed.

• Keywords: building environment, civil engineering, thesis, convection, insolation, shading, temperature measurements, arch-gravity concrete dam, Moste Dam, thermal analysis, stress-strain analysis, uncertainty analysis