Toplotna analiza velikih ločno-težnostnih betonskih pregrad : doktorska disertacija
Thermal analysis of large arch-gravity concrete dams : doctoral thesis

slovenian

doktorska dela

2017

arch-gravity concrete dam   civil engineering    convection    insolation    Moste Dam   shading    stress-strain analysis    temperature measurements   thermal analysis    thesis    uncertainty analysis 

Univerza v Ljubljani, Fakulteta za gradbeništvo in geodezijo

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.

09.09.2019