Hrvatske vode
 
Lučni riječni pragovi
Arch-shaped sills

Goran Gjetvaj1, Antonija Cikojević1, Filip Ferenčak2, Josip Husajina3

Sažetak/Abstract: 

U okviru uređenja prirodnih vodotoka, s ciljem smanjenja hidrauličke erozije koja uzrokuje produbljenje dna te time i sniženje razine površinskih i podzemnih voda, često se grade pragovi. Pragovi od kamenog nabačaja građeni okomito na smjer toka vode su iz estetskih razloga prihvatljivi, ali su u uvjetima velikih protoka podložni urušavanju. Iskustva s urušavanjem pragova na Savi kod Zagreba i Ljubljane su potakla istraživanja s ciljem iznalaženja tlocrtnog oblika pragova otpornijih na hidrauličku eroziju. U radu je prikazana usporedba stabilnosti ravnog i lučnog praga izvedenog od kamenog nabačaja. Na izgrađenim fizikalnim modelima su provedena mjerenja s osnovnim ciljem ocjene utjecaja tlocrtnog oblika praga na stabilnost. Prikazana je usporedba dvaju tipova pragova (ravnog i lučnog) gdje je pri jednakim hidrauličkim uvjetima za oba oblika mjeren broj odnesenih čestica i vrijeme u kojem dolazi do urušavanja konstrukcije. U radu su analizirane dominantne sile koje djeluju na čestice te je analiziran učinak ukliještenosti kod lučnog oblika praga.

 

Sills are often constructed as part of the regulation of natural watercourses to reduce hydraulic erosion that causes riverbed deepening and thus also the lowering of surface and ground water levels. Riprap sills constructed vertically in relation to the direction of the water flow are aesthetically acceptable; however, they tend to collapse in high discharge conditions. The experiences with sill collapses on the Sava River at Zagreb and Ljubljana initiated research geared at finding a layout sill shape that is more resilient to hydraulic erosion. The paper presents a stability-related comparison between straight and arch-shaped riprap sills. The measurements were conducted on the constructed physical models with a primary goal to assess the impact of a layout sill shape on the stability. During the comparison between the two sill types (straight and arch-shaped), in the same hydraulic conditions, the number of particles washed away and the time needed for structure collapse were measured. The paper analyses the dominant forces affecting the particles and the impact of particle adhesion for arch-shaped sills.

Kategorija: 
Stručni članak / Professional Paper
Ključne riječi/Key words: 

riječni prag, luk, vodotok

bed sill, arch-shaped, watercourse

Podaci o autorima/Authors affiliations: 

1Građevinski fakultet Sveučilišta u Zagrebu, Kačićeva 26, 10000 Zagreb, goran@gradri.hr

 

2Hidrokonzalt projektiranje, d.o.o., Hvarska 11, 10000 Zagreb

 

3Elektroprojekt, d.d., Alexandera von Humboldta 4, 10000 Zagreb

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