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U ovom radu su opisani primjeri povecanja stupnja hazarda zbog podizanja razine Jadranskog mora. Takoder je opisano povecanje rizika prouzrocenog cešcim pojavama nestabilnosti razlicitog tipa na obalnim padinama. Dat je pregled ranjivosti obala u podrucju Kvarnera, kao kanalskog dijela sjevernog Jadrana, koji je otocnim nizovima podijeljen na Rijecki zaljev, Kvarner, Kvarneric i Vinodolsko-Velebitski kanal. U obalnom pojasu podrucja Kvarnera prevladavaju karbonatne stijene, dok su siliciklasticne stijene - fliš, reduciranog prostiranja. Kvartarni sedimenti s znacajkama tala, djelomicno pokrivaju osnovne stijene. Na relativno rezistentnim karbonatnim stijenama, koje prevladavaju na obalama, ucinak marinske erozije je slabo izražen. Flišna stijenska masa je opcenito manje otporna na djelovanje marinske erozije. Medutim, ti dijelovi obale zašticeni su tijelima žala koja su se oblikovala tijekom milenijske stagnacije morske razine. Prema novim predvidanjima, može se ocekivati ubrzani rast razine Jadranskog mora u rasponu od 20 do 60 cm do kraja 21. stoljeca. 1. prosinca 2008. godine na mareografu kod Bakra zabilježena je do sada najviša morska razina od 117 cm iznad srednje razine. U tim danima puhali su jaki vjetrovi iz južnog kvadranta pa se moglo ocekivati da ce dijelovi obala otvorenih prema valovima iz tih smjerova biti osobito izloženi destruktivnom djelovanju. Obilaskom više lokacija utvrdeno je izraženo potkopavanje nožica u manje rezistentim sedimentima. Takoder je primijeceno potkopavanje nožica i padanje blokova u karbonatnim stijenama. Primjetna su premještanja dijelova tijela šljunkovitih žala, kako i promjena njihovog oblika. Znacajne štete vidljive su i na obalnim gradevinama. U bliskoj buducnosti ocekuju se cešce pojave ekstremno visoke razine mora (acqua alta) što ce ubrzati geomorfološke procese i potencirati pojave nestabilnosti na obalama Kvarnera.

Lujzinska cesta na izlazu iz Rijeke u smjeru Karlovaca izgrađena je 1804. godine i to zasjecanjem vrlo strmih litica u kanjonu Rječine i izvedbom visokih nasipa uglavnom poduprtih visokim i složenim potpornim konstrukcijama. Zbog takve morfologije terena cijeli potez ceste od Rijeke do Orehovice, na izlazu iz kanjona Rječine, zasječen je karbonatnim naslagama kredne i palogenske starosti visine do nekoliko desetaka metara. Vapnenačka stijenska masa u zasjecima je izrazito okršena i raspucala te su pojave nestabilnosti uslijed korozivnog rada vode u pukotinskim sustavima poslijednjih godina postale učestale. Pojave nekoliko većih nestabilnosti uslijed kojih je došlo do odronjavanja većih količina stijenskog materijala na prometnicu, ukazale su na potrebu detaljnog istraživanja stanja stabilnosti pokosa te izrade potrebnog projekta sanacije. Istražni radovi obuhvatili su snimanje stanja zasjeka metodom terestičke fotogrametrije te inženjerskogeološkog kartiranja postojećeg stanja. Iz razultata kartiranja utvrđeni su modeli stanja te mehanizmi mogućih pojava nestabilnosti. Na osnovi terenskog i laboratorijskog ispitivanja stanja stijenske mase i diskontinuiteta utvrđeni su kriteriji čvrstoće stijenske mase i diskontitnuiteta. Izrađeni su geotehnički modeli stijenskih pokosa na kritičnim dionicama i za utvrđene kriterije čvrstoće provedene geostatičke analize. Rezultati provedenih analiza ukazali su na potrebu dodatnog ojačanja stijenske mase radi postizanja potrebnih faktora sigurnosti. Ojačanje stijenske mase pokazalo se neophodnim s obzirom da vrlo strmi nagib stijenske padine nije omogućavao promjene postojeće geometrije zasjeka. Za osiguranje traženih faktora sigurnosti odabrani su različiti tipovi podgradnih sustava u zavisnosti od visine zasjeka, značajki stijenske mase te mogućih mehanizama sloma. Ojačanje stijenske mase provedeno je upotrebom štapnih sidara i mlaznog betona na licu zasjeka na lokacijama izuzetno trošne stijenske mase ili vrlo nepovoljnih pukotinskih sustava gdje je postojala opasnost pojave odrona većih dimenzija, upotrebom štapnih sidara i žičanih mreža ojačanih čeličnom užadi na mjestima mogućeg ispadanja pojedinih blokova te upotrebom mjera za zaštitu od erozije. Radovi na ojačanju stijenske mase na predmetnim lokacijama provedeni su tijekom ljeta 2005. godine. Ovim radom daje se pregled provedenih istražnih radova za potrebe određivanja značajki sijenske mase i diskontinuiteta, provedenih analiza stabilnosti kao i tijek radova na potrebnom ojačanju stijenske mase opisanim metodama.

For the past few years in the area of the city of Rijeka, Croatia, a few open pits in limestone rock mass were excavated. Design and construction works required complex geotechnical investigations. On the basis of the geotechnical investigation results designs of support systems of the cut in limestone rock mass were prepared. While designing the construction of the open pits all accepted features of the reinforcement rock mass behavior were used. The support systems of the cut in the rock mass were made by the reinforcements from rock bolts and multy-layered reinforced sprayed concrete (shotcrete). During the works execution, a measuring, observing and monitoring system for the support system behavior was established. The monitor-ing system included deformation measuring in horizontal deformeters and vertical inclinometers, and obser-vations of geodetic marks. This enabled to obtain the data necessary for the stress-strain back analysis of the real behavior of excavated rock mass. An active design procedure was established which made possible changes required in the rock mass reinforcement system in cuts. The back analyses results have indicated nec-essary changes the in the approach of the construction and designing of the reinforcement systems for secur-ing the slopes of the cut in the rock mass. Performed back stress-strain analysis also showed need for the addi-tional correction in the correlations between deformation characteristics of the rock mass and rock mass classification. In this paper we present some acquired experiences during open pit excavations in limestone rock mass through some constructed buildings and observed exceptions from accepted features of the rein-forcement rock mass behavior.

On the Zagrad location, in the very vicinity of the Rijeka city center, the garageaccommodation- business complex is under construction, layout dimensions 90 x 60 m. The geotechnical conditions on site are very complex: on the lateral sides limestone rock-mass protrudes to the surface while in the central part of the location is a sinkhole with thick clay deposits. Regarding the location morphology, the construction pit being 2 m deep on the northern end of the location to the 5 m depth on the southern end - adjacent to the existing buildings and a traffic line-was designed. For the designing of the excavation, the support system and the building foundation design, a complex geotechnical investigation was performed. These investigation works included borehole drilling, geophysical measurements, laboratory testing of rock and soil specimens. In the northern end of the location, having the highest cut in the carbonate and flysch rock mass, investigation boreholes and seismic refraction were carried out, along the future excavation pit contours. The analysis of the refraction data was made by the inverse modeling (Delta T-V method). The results obtained by these methods were used to determine the geotechnical profile, the contacts between flysch deposits and carbonate rock mass. On the same basis the rock mass parameters for the walls of the future excavation pit were evaluated and used for the rock support design. On the lowest, southern, part of the site the main problem encountered was determining the location of the bedrock on which the foundation of the building was foreseen. On that part of the site investigation boreholes were drilled and ground probing radar scanning performed. This was allowed to determine cover deposits, weathered zones and basic rock masses in the soil. On the basis of the data collected, pit excavation methodology, rock support and foundation design options for that part of the site are taken. Due to the great variations in the cover thickness, the building foundation was designed as a combination of shallow foundations on easy-to-reach carbonate rock base, and deep foundations on toploaded drilled piles. During the construction of the pit and building foundations, the design assumptions were adapted according to the in situ situation.

Čabranka River is a bordering river between the Republic of Croatia and Slovenia, with its channel deeply cut into the rock mass of Gorski kotar region. A reconstruction works on a road on the Croatian side, right next to the Čabranka channel, required a widening which could have been made only by undercutting into the very steep slopes of heterogeneous geological composition. Due to a covered terrain, and very unfavorable hydrological conditions during works execution, on a relatively short section, several instabilities with different mechanisms occurred: planar and wedge failure in rock mass, and soil sliding in soil deposits on steep bedrock. This paper presents instabilities mentioned above and description of their formation mechanisms. In order to determine the situation and make the remediation design, field investigations were performed: boring, geophysical surveying, engineering geological and geotechnical investigations. Results of investigations, as well as the slope stability analysis and designed remediation measures for the largest landslide are also presented.

On the location Zagrad in Rijeka, Croatia, an open pit has been designed and constructed for the purpose of building the garageaccommodation- business complex. The location of the open pit is situated in the central area of the town Rijeka, and closely surrounded by the existing accommodation buildings, a traffic line and a railway. The open pit was designed and constructed four levels below the terrain surface, adjacent to the existing buildings and a traffic line. To secure the open pit walls during excavation, a support system with the selfdrilling rock bolts for the reinforcing of the rock mass and reinforced concrete grid structure on the excavated surface was designed. This paper presents the construction method for the open pit, with the application of active design concept during works execution. It also presents the set-up system for measuring, observing and monitoring of the support system behavior. This enabled, on the basis of the measurement results and performed back analysis, an active designing of the suitable support system during works execution, for the in situ conditions of the rock mass in excavation. Performed back analysis showed need for the additional correction in the correlation between deformation characteristics of the rock mass and rock mass classification.

This paper presents hydrogeological conditions in coastal area of Rijeka, which have changed considerably over the last 150 years, since development of the city and spreading of the port began. We analyzed risks caused by planned constructions and long-term impact of expected sea-level rise on hydrogeological conditions and groundwater flow dynamic.

The paper presents the construction of an open pit within the urban area, by application of the phase excavation concept and active design of the rock bolts reinforcement system for the flysch rock mass. By the end of the open pit excavation works, monitoring of the excavation stated great deformations in the area excavated in flysch deposits. The stability of the excavation was established by the well-timed intervention and additional reinforcement measures, without influence on the adjacent buildings.

This paper presents the linkage between geomorphologic characteristics of the relief, tectonic structures, lithologic composition of deposits on the Krk island, and the degree of natural hazard and geotechnical risk. The influence of geotechnical risk on the physical planning is analysed, as well as the experiences and construction defaults in some urban locations. All rocks and soils on the Krk island in form three specific types of ground with different lithological composition and geotechnical properties and therefore quite different geohazard degree. They are: karst area, flysch area and alluvial area. Generally speaking, karst area is the most favourable for constructing, because has the lowest degree of geohazard, but this type of ground also comprises a great number of sites which are less favourable for construction. Flysch area has the higher degree of geohazard than karst area. Some geotechnical very favourable sites are situated on flysch type of ground. However, on these sites the old towns are located with lesser possibility for theirs expansion. Alluvial areas are greatly covered by the agricultural land and therefore they are inadequate for urbanisation.

U radu su prikazani rezultati istraživanja prve i druge faze složenog klizišta na sjeveroistočnoj padini doline Rječine između brane Valići i naselja Pašac. Bokovi doline oblikovani su u paleogenskom flišu i kvartarnim padinskim tvorevinama. Na vrhovima su zastupljene vapnenačke stijene tvoreći litice. Nastanak istražene kompleksne pojave klizišta predodređen je geološkom građom i morfogenezom doline Rječine. To je složeno retrogresivno klizište, koje se počelo razvijati od stope prema vrhu padine. Na padini je otkriveno 13 pojedinačnih kliznih tijela. Klizanjem je zahvaćen materijal padinskih tvorevina. Klizna ploha uglavnom je predisponirana morfologijom flišne podloge. Veći dio kliznog tijela saturiran je podzemnom vodom koja se procjeđuje kroz pokrivač po kontaktu s nepropusnom flišnom podlogom. Pokrenuti su i megablokovi vapnenačke stijene na vrhu padine, koji klize po flišnoj podlozi. To je posebna pojava, netipična za klizišta na flišnim padinama u široj okolici Rijeke. Vapnenci na litici jako su oštećeni i u njima su vidljive svježe pukotine.

This piece of work presents the “small” landslide occurrences in the part of the Istrian peninsula, named “Grey Istria”, where the Paleogene flysch sediments shaped the terrain. This is the area of the very significant exogenetic processes, like erosion and accumulation of material. The fore mentioned landslides are of the relatively small dimensions and with landslide body volume lesser than 20.000 m3. The sliding of material regularly occurs inside the weathering zone or in slope formations, while the slide surface is formed in the contact with the flysch bedrock. This paper deals with the landslide in the vicinity of the Krušvari settlement, which caused the damage of the local road in the section of Cerovlje-Buzet. It could be said that particular landslide is the typical one for the “Grey Istria” area, while its causes and sliding phenomena are similar to the numerous landslides in this region.

U radu su prikazani rezultati istraživanja prve faze složenog klizišta na sjeveroistočnoj padini doline Rječine između brane Valići i naselja Pašac. Bokovi doline oblikovani su u paleogenskom flišu i kvartarnim padinskim tvorevinama. Na vrhovima su zastupljene vapnenačke stijene tvoreći litice. Nastanak istražene kompleksne pojave klizišta predodređen je geološkom građom i morfogenezom doline Rječine. To je složeno retrogresivno klizište, koje se počelo razvijati od stope prema vrhu kosine. Na padini je otkriveno 13 pojedinačnih kliznih tijela. Klizanjem je zahvaćen materijal padinskih tvorevina i dio kore fizičko-kemijskog raspadanja. Veći dio kliznog tijela saturiran je podzemnom vodom koja se procjeđuje kroz pokrivač po kontaktu s nepropusnom flišnom podlogom. Klizanje je relativno plitko budući da u hidrotehničkom tunelu, koji se nalazi ispod nožice klizišta, nisu uočena oštećenja prouzročena klizanjem. Pokrenuti su i megablokovi vapenačke stijene koji, najvjerojatnije, klize po flišnoj podlozi. To je posebna je pojava, netipična za klizišta na flišnim padinama u široj okolici Rijeke. Vapnenačka stijena na litici je jako dezintegrirana, a u njoj su vidljive svježe pukotine. Istraživanja su se sastojala od geodetskih mjerenja, geofizičkih, inženjerskogeoloških i geotehničkih istraživanja. Geodetsko snimanje obavljeno je metodom terestičke fotogrametrije. Rezultati su uspoređeni s aero snimcima učinjenim godine 1981. Tako su se mogle otkriti promjene morfologije padine u razdoblju od 1981. do 1997. godine. Fotoskice su korištene i za dopunu inženjerskogeološkog kartiranja. Geofizičko mjerenje je obavljena metodom plitkog seizmičko-refrakcijskog profiliranja.

Na hrvatskoj obali Jadranskog mora prirodna šljunkovita i pjeskovita žala su rijetka. Slična je situacija i na području Kvarnera...

Gravel and sand beaches are very rare on the Coastal Coast of the Adriatic Sea and Rijeka Bay conforms to this pattern This is because of geological composition, morphological evolution and specific maritime conditions.