Index Geophysics

eng THE SIGNIFICANCE OF STRUCTURAL AND GEOLOGICAL RELATIONSHIP ASSESSMENT IN THE CONSTRUCTION OF THE OMBLA UNDERGROUND HYDROELECTRIC POWER PLANT

hrv ZNAČAJ STRUKTURNIH I GEOLOŠKIH ODNOSA U KONSTRUKCIJI PODZEMNE HIDROELEKTRANE OMBLA

eng The construction design of the underground hydroelectric plant Ombla required geological and structural investigations to he carried out. Due to past earthquakes in the area permanent tectonic movements were inferred. Therefore, in the wider and adjacent surroundings of the Ombla spring it was necessary to analyze the structural fabric and the geodynamic characteristics of the area. The most active zone encountered is the front part of a thrust fault belonging to the Dinaricum regional structural unit. The compressive regime is maintained as a response to the regional stress of an approximately S-N orientation. Different displacements of various parts of the Dinaricum unit are present. Along the rim of the structural blocks, the Hum-Om-bla fault zone extends, accompanied by left transcurrent faults, Through this zone the main groundwater drainage occurs supplying the Ombla spring. In the local Ombla spring area this zone is characterized by three sub-blocks and three major faults. The most important fault for the vital facilities of the Ombla hydroelectric power plant is the Pločice fault which divides the structural sub-blocks. Along this fault zone there are four mutually connected. The lowest two arc active groundwater draining systems supplying the Ombla spring. The data on local stress implies the following deformation of sub-blocks: sub-blocks 2c and 2f are displaced along normal faults from 20° to 30° to the left, downwards, while the sub-block 2 d is displaced along the Pločice thrust fault of 100° to 130° to the left, upwards. The structural data confirmed that the building of an underground dam with a height from 100 to 130 m was feasible. The connection between the caverns and the fault zone was determined. The unfavorable position of the active Pločice fault zone imposes the construction of vital Ombla power plant facilities underground.

hrv Za potrebe izgradnje podzemne hidroelektrane Ombla izvršena su i strukturno-geološka istraživanja. Zbog pojava potresa znalo se za postojanje stalne tektonske aktivnosti. Stoga se u širem i lokalnom prostoru oko izvorišta Ombla pristupilo razradi strukturnog sklopa i geodinamičkih odlika prostora. Najaktivniju zonu predstavlja čelo navlake regionalne strukturne jedinice Dinaricuma. Djelovanje regionalnog stresa približne orijentacije J-S stvara kompresijski režim. Postoje različiti pomaci dijelova jedinice Dinaricuma. Granicom strukturnih blokova proteže se zona rasjeda Hum-Ombla s prisutnim lijevim transkurentnim pomacima. Kroz tu zonu postoji glavni dovod podzemne vode na izvorište Ombla. U lokalnom prostoru unutar te zone izdvajaju se tri strukturna potbloka i tri važna rasjeda. Za vitalne objekte HE Ombla značajan je rasjed Pločice koji odvaja strukturne potblokove. Duž njegove zone u prostoru su formirana četiri povezana nivoa šupljina. Dva donja predstavljaju aktivan dovod vode na izvorište Ombla. Podaci o lokalnom stresu ukazuju na deformacije potblokova i to: potblokovi 2c i f pomiču se duž normalnih rasjeda od 20° do 30° lijevo, dolje, a potblok 2 d duž reversnog rasjeda Pločice od 100° do 130° lijevo, gore. Strukturni su podaci potvrdili mogućnost izgradnje podzemne brane visine od 100 do 130 m. Utvrđena je povezanost šupljina sa sustavima rasjeda. Nepovoljni položaj aktivne zone rasjeda Pločice u prostoru uvjetuje projektiranje vitalnih objekata HE Ombla u podzemlju.

Buljan, Renato

Prelogović, Eduard

eng structural fabric;tectonic movements;underground hydroelectric power plant;Ombla;Dubrovnik

hrv struklurni sklop;tektonska aktivnost;podzemna hidroelektrana; Ombla;Dubrovnik

Faculty of Mining, Geology and Petroleum Engineering University of Zagreb

1997

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Rudarsko-geološko-naftni zbornik

ISSN 1849-0409 (Online)

Volume 9

Issue 1

eng

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