Katastrofické poruchy sypaných hrází

Failures of embankment dam

habilitation thesis

Czech

Vytvořením vzdouvací stavby a jejím provozem vzniká riziko katastrofické poruchy její hráze. Při katastrofickém prolomení (protržení) hráze vzdouvací stavby vznikne zvláštní povodeň, která může vyvolat ztráty na lidských životech, ztráty na majetku, poškození životního prostředí, atd. Znalost o rozsahu území ohroženého zvláštní povodní slouží jako podklad pro vypracování evakuačních plánů s cílem redukovat výši povodňových škod.

The existence of the dams retaining water either permanently or occasionally, is always connected with the risk of their failure. The failure of a dam gives rise to a flood wave that advances in the area behind the dam or through the valley below the dam. The effects of a dam break wave originated in this way may be disastrous and may cause numerous fatalities as well as financial losses exceeding many times the price of the hydraulic structure itself. It is necessary to take into account the fact that no dam design can ensure the "absolute" protection of potentially endangered areas. This especially applies in the case of levees on rivers where the degree of protection is determined as early as at the design stage. Absolute safety cannot be expected even in large dams, and there is always a risk, even if a very small one, of their overtopping or of another kind of failure (e.g. internal erosion, sabotage, etc.). The presented work deals with the evaluation of the possibilities of occurrence and the progress of embankment dam failures due to overtopping and due to global stability. The work provides comprehensive database of dam failures all over the world and the statistical analysis of data dealing with dam construction and dam failures. Also describes several approaches to the deterministic modelling of the dam breaching due to overtopping. For the first estimate of dam breach parameters (peak discharge, time of failure, shape and size of the breach) the empirical formulas derived from real dam failures are mentioned and discussed. Further on, the mathematical model of the dam failure is described. Latin Hypercube Sampling method was used for the estimate of the probable worst possible, but realistic flood hydrograph. The other of the possible dam failure is slope stability failure. Traditionally, a deterministic approach is usually used for such analysis. However, the determination of variables such as soil strength parameters involves uncertainties, which cannot be handled in the traditional deterministic methods. To perform the reliability analysis of a slope, method of reliability index is proposed. The method is extremely useful mainly because the probability distributions of the soil properties are usually not available.

porušení sypané hráze; prolomení hráze; přehrada, přelití; statistika poruch hrází; příčiny poruch; modelování porušení; zvláštní povodeň; odhad spolehlivosti; index spolehlivosti; modelování proudění

failure of embankment dam; dam breach; dam; overtopping; failure statistics for dams; types of failures; modelling of dam breach; dam break flow; index reliability; dam break flow modelling

JANDORA, J.

1. 12. 2007

VUT v Brně

Brno University of Technology, Faculty of Civil Engineering, Institut of Water Structures

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