ZNAČAJ STRUKTURNIH I GEOLOŠKIH ODNOSA U KONSTRUKCIJI PODZEMNE HIDROELEKTRANE OMBLA

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.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

ZNAČAJ STRUKTURNIH I GEOLOŠKIH ODNOSA U KONSTRUKCIJI PODZEMNE HIDROELEKTRANE OMBLA

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.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

Correlation of Quaternary Sediments and Tectonic Activity of the Eastern Part of the Drava River Depression

The Holocene, Upper Pleistocene and Middle Pleistocene sediments in the eastern part of the Drava depression the substratum of which is determined by the conditional EK marker Q\u27, are composed in the lower part mainly of silts and clays and in the upper part of sands. The thickest parts are about 400m. The composition of the transparent heavy minerals and the result of the paleontological treatment show that the sedimentation was in the lake or swamp with the origin of detritus from the metamorphic rocks and smaller quantity of older clastic sediments.The collected data show the quaternary tectonic activity after the sedimentation of the marker horizon Q\u27. In the area between the boundary faults of the valley, the faults of the system E.N.E. - W.S.W. (N.E. - S.W.) influenced directly the sedimentation and the folding . They were the consequence of the regional movements and stress strain behaviour of rock masses, which built the structures of the valley.As a result, the horizontal component of the left wing movement is visible along the diagonal system of faults. The vertical movements have also been determined. The greatest amplitudes were along the boundary South fault of the Drava valley, up to 350 m for the period of Middle and Upper Pleistocene, or 90 m for Upper Pleistocene only

GEOTEHNIČKI MODELI TEMELJENJA MOSTA MASLENICA

On the site of Maslenica bridge structural tectonic, geophysical and engineering geological investigations, geotechnical drilling and laboratory sample testings were performed. Maslenica anticline is characteristic for the investigated area. It is built from the limestone of Cretaceous age. The anticline has an asymmetrical form with the vergence of the axial plane towards the north. Reverse faults with recent activities are present. The recent activity was proved by the discovery of the broken stalactite with the displacement of 11 cm, whose age is 36000 years. On quite young stalactites (stalagmites) in the cave on the west side, no displacements were noticed. For the next period of 500 years the maximal possible displacement of 2.0 cm is foreseen. Smaller caves with the dimensions of 1 m3, were formed on the intersections of the reverse faults and greater joints. The canyon Novsko ždrilo was formed in the fault shear zone with tectonic transport to the right. According to the range of fracture, three characteristic types of rock masses were separated by engineering geological investigations. According to »Geomechanical classification« (RMR) the first type corresponds to II to III class, while the second type corresponds to IV class, and the third type corresponds to V class (mylonite). Because of the complexity of the terrain structure, original engineering geological bases of design have not enabled the direct application of the analysis of stress-strain behaviour. Because of that the simplified geotechnical models were done. They enabled the projecting of foundation in the rock mass and renewal of poor quality rock mass.Na lokaciji Masleničkog mosta urađena su strukturno-tektonska. geofizička i inženjerskogeološka istraživanja, istražna bušenja i laboratorijska ispitivanja uzoraka. Za istraživano područje karakteristična je Maslenička antiklinala. Izgrađena je od vapnenaca kredne starosti. Antiklinala ima asimetričan oblik s vergencijom osne ravnine prema sjeveru. Prisutni su reversni rasjedi s recentnom aktivnošću. Recentna aktivnost dokazana je nalazom presječene sige s pomakom od 11 cm, čija starost je 36000 god. Na sasvim mladim sigama u špilji na zapadnoj strani nisu uočeni pomaci. Za povratni period od 500 godina progno¬ziran je mogući maksimalni pomak veličine do 2,0 cm. Manje špilje dimenzija do 1 m3 nastale su na presjecištima reversnih rasjeda i većih pukotina. Kanjon Novsko ždrilo nastao je u zoni smicanja rasjeda s desnim tektonskim transportom. Prema stupnju razlomljenosti izdvojene su inženjerskogeološkim istraživanjem tri karakteristične sredine. Prema »Geomehaničkoj klasifikaciji« (RMR) prva sredina odgovara II, do III. klasi, druga sredina odgovara IV. klasi, a treča sredina odgovara V. klasi (milonit). Originalne inženjerskogeološke podloge nisu omogućile, zbog složenosti građe terena, direktnu primjenu u analizi odnosa naprezanja i deformacija. Zbog toga su izrađeni simplificirani geotehnički modeli. Oni su omogućili projektiranje temeljenja u stijenskoj masi i saniranja dijelova slabe kvalitete

POMACI STRUKTURA I SEIZMOTEKTONSKA AKTIVNOST ZAPADNOG VELEBITA: NEKA NOVA OPAŽANJA

A permanent seismotectonic activity is present in the region of northern Velebit. Through history a number of earthquakes magnitudes of VIII° and IX° MCS are reported. In this century the most powerful earthquake of a magnitude of 5.8 occurred in 1916. The key tectonic movements that cause these earthquakes are dislocations of the Adriatic platform towards the north and the resistance of the Dinarides towards these movements. The tectonic dynamics of a structural arrangement depend on the relationship between stress and the deformation of structural units. According to the tectonic measurements performed on outcrops of major faults the following orientation of stress was obtained: from 20/25° to 200/205° in the northern Velebit region and 340 to 160° in the hinterland. Within the structural arrangement compression of space occurs which is well pronounced in the Novi Vinodolski area. Possible deformation of structures is manifested spatial diagonal reverse displacements accompanied by rotation of the structure. In the Velebit hinterland right horizontal tectonic transport was determined. In the zone of the transcurrent faull Žuta Lokva-Otočac-Bunić the spatial opening leads to the formation of pull-apart structures. Seismotectonically active zones occur in the contact region between the Adriatic platform and the Dinaridcs. Spatially its position is inclined and bent.U području sjevernog Velebita stalno je prisutna seizmotektonska aktivnost. U povijesti se više puta spominju potresi intenziteta VII° i IX° MCS. U ovom stoljeću najjači potres dogodio se 1916. godine magnitude 5,8. Ključni tektonski pokreti koji uzrokuju pojavljivanje potresa jesu pomaci Jadranske platforme prema sjeveru i odupiranje Dinarida tim pomacima. Tektonska dinamika strukturnog sklopa ovisi o odnosu stresa i deformacija strukturnih jedinica. Prema podacima terenskog mjerenja u izdancima najvažnijih rasjeda dobivena je orijen¬tacija stresa: u sjevernom Velebitu 20/25°-200/205° i u zaleđu 340-160°. U strukturnom sklopu nastaje kompresija prostora osobito izražena oko Novog Vinodolskog. Moguće deformacije struktura jesu dijagonalni reversni pomaci u prostoru uz rotaciju struktura. U zaleđu sjevernog Velebita utvrđen je desni horizontalni tektonski transport. U zoni transkurentnog rasjeda Žuta Lokva-Otočac-Bunić otvaranjem prostora oblikuju se strukture tipa pull-apart. Seizmotektonski aktivna zona pojavljuje se u prostoru dodira Jadranske platforme i Dinarida. Značajan je njezin kosi položaj u prostoru uz koncentraciju žarišta resa na dubinama do 34 km

Characteristics of the Dugi Otok Fault in the Area of Šibenska Rogoznica (Dalmatia)

Obrazlaže se neotektonska i recentna tektonska aktivnost u zoni Dugootočnog rasjeda. Navode se podaci o strukturnom sklopu kopnenog dijela razmatranog područja. Uspoređuje se površinska i dubinska geološka građa i opisuju tektonska kretanja. Naglasak se stavlja na podatke o recentnoj aktivnosti.The neotectonic and recent leotonic activity in the zone of the Dugi Otok fault is discussed. Data on the structure of the mainland part of the area investigated are put forward. The surface and subsurface geological structures are compared and the tectonic movements are described. The main emphasis is put on the data reffering to the recent activity

Seizmičnost Hrvatske u razdoblju 1993-1996. i potres u području Stona i Slanog iz 1996. godine

Seismic activity in Croatia and surrounding areas in the 1993-1996 period was mostly confined to the previously identified seismically active areas. Nine events (excluding aftershocks) with the magnitude equal to or exceeding 4.5 occurred during that time. The most important earthquake sequence is the one that started on September 5, 1996 (Ml=6.0, Imax=VIII MSK) in the Ston-Slano area (greater Dubrovnik region). Microseismic locations of hypocentres of thousands of aftershocks, as well as the best double-couple CMT solution for the main-shock indicate that the earthquakes occurred on the NW-SE striking reverse fault system dipping towards NE

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

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

GEOTECHNICAL MODELS OF THE ARCH FOUNDATIONS OF THE MASLENICA BRIDGE

On the site of Maslenica bridge structural tectonic, geophysical and engineering geological investigations, geotechnical drilling and laboratory sample testings were performed. Maslenica anticline is characteristic for the investigated area. It is built from the limestone of Cretaceous age. The anticline has an asymmetrical form with the vergence of the axial plane towards the north. Reverse faults with recent activities are present. The recent activity was proved by the discovery of the broken stalactite with the displacement of 11 cm, whose age is 36000 years. On quite young stalactites (stalagmites) in the cave on the west side, no displacements were noticed. For the next period of 500 years the maximal possible displacement of 2.0 cm is foreseen. Smaller caves with the dimensions of 1 m3, were formed on the intersections of the reverse faults and greater joints. The canyon Novsko ždrilo was formed in the fault shear zone with tectonic transport to the right. According to the range of fracture, three characteristic types of rock masses were separated by engineering geological investigations. According to »Geomechanical classification« (RMR) the first type corresponds to II to III class, while the second type corresponds to IV class, and the third type corresponds to V class (mylonite). Because of the complexity of the terrain structure, original engineering geological bases of design have not enabled the direct application of the analysis of stress-strain behaviour. Because of that the simplified geotechnical models were done. They enabled the projecting of foundation in the rock mass and renewal of poor quality rock mass

Geodynamics of the area of the City of Zagreb

U radu se prikazuju interdisciplinarna istraživanja geodinamičkih procesa šireg prostora Grada Zagreba. Predmetna istraživanja izvode se unutar projekta "Geodinamička mreža Grada Zagreba", uz dominantan angažman geodetskih znanstvenika i znatnu pomoć drugih geoznanstvenih disciplina. Prvi rezultati i njihova analiza uz pomoć znanstvenoga GAMIT softvera, nakon izvršenih triju serija GPS-mjerenja pokazuju zamjetnu aktivnost geodinamičkih procesa na promatranom prostoru. Radi što pouzdanije analize i primjene dobivenih rezultata, planira se oplemeniti istraživanja uključivanjem novih mjerenja i proširenjem istraživačkog tima novim geoznanstvenicima. Nastavak istraživanja planiran je kroz realizaciju projekta "Geodetsko-geodinamička studija prostora Grada Zagreba".This paper presents interdisciplinary research of geodynamic processes of the wider area of the City of Zagreb. Research is conducted under the project "Geodynamic network of the City of Zagreb", with dominant participation of geodesists with significant contribution of other geoscientists. After three series of GPS-measurements, the analysis of the first results with scientific software GAMIT show significant geodynamic activity in the research area. In order to get more reliable results, new measurements have been planned as well as adding new geoscientists to the research team. The continuation of the research is foreseen through the project "Geodetic-geodynamic study of the area of the City of Zagreb"