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This paper describes numerical modeling of the Kostanjek landslide using the LS-Rapid software. The analyses using the LS-Rapid software were made for two different triggering factors i.e. excess of pore water pressure, and combination of pore water pressure excess and earthquake occurrence, and it was applied at two different landslide cases. In the first case, the LS-Rapid software was used to re-examine the landslide model for the Kostanjek landslide reported by Ortolan (1996), Mihalinec and Stanić (1991) and Stanić and Nonveiller (1996). In the second case, LS-Rapid was used to confirm the Kostanjek landslide model in which the sliding surfaces are initially developed through the soil mass. During the initial shearing, the excess pore pressure is often generated during the landslide activations by triggering factors and the post failure-motion of the landslide. The strength parameters used in these analyses were derived from tests in undrained ring shear apparatus carried out by Oštrić et al. (2012 a, b). It is expected that the results of the Kostanjek Landslide simulation using LS-Rapid software and parameters obtained from undrained tests carried out in ring shear apparatus would give realistic results and would help for better understanding of the Kostanjek landslide behavior.

The method for the design and realization of systems for ensuring stability of cuts in flysch formations, with an interactive approach based on stress-strain back analyses, is presented. Flysch formations can be regarded as materials belonging in a transitional zone between soft rocks and hard soils. Based on results obtained by laboratory and in-situ investigations in various stages of design and realization of projects, it can be concluded that the strength and deformability parameters for flysch can not accurately be determined by traditional methods, and that it is very difficult to adopt realistic design parameters. An interactive design procedure to be applied during realization of cut support constructions in flysch formations is proposed. The use of proposed methods is presented and illustrated by examples of cuts realized in flysch on the Adriatic motorway route in the vicinity of the town of Rijeka, Croatia. Design procedures used for ensuring stability of cuts are based on results obtained by geotechnical investigations as well as on classifications for heterogeneous rock formations. The system for monitoring behaviour of flysch formations in cuts is established, and flysch formations are classified in open side cuts through geotechnical supervision. Relevant data are used in stress-strain back analyses, so as strain properties of flysch are varied in order to harmonize measured and calculated displacements at cut locations. The results of these analyses either confirm the predictions or require modifying the design support systems in order to ensure cuts stability in flysch formations.

The Čabranka river is a bordering river between the Republic of Croatia and Republic of Slovenia. River valley is cutted in broken anticline consisted of Permian clastic sedimentary rocks. Rock mass has lithological heterogeneity. It mostly consists of micaceous shale’ s, sandstones and quartz conglomerates. This sedimentary rock mass is folded, faulted and extensively fractured which enabled separation and disintegration of rocky blocks, and accumulation of falling material on the scarp foot and in Čabranka riverbed respectively. Bedrock is covered by debris formations which are consist from sandy and silty clay mixed with coarse fragments and boulders. The natural slopes near road are very steep and debris formations are potentially unstable. Geohazad of mass movement in the Čabranka valley is very high. The regional road between Čabar and Zamost is mostly located along and near the southern coast of Čabranka channel. This road is up to 5 m wide and is inadequate to modern traffic, and road fill is permanently undercutted by river flow. For the purpose of its reconstruction, undercutting into the very steep slopes was designed and constructed. The previous geotechnical investigations were not performed before design of road reconstruction. Due to a heterogeneous geological composition and a complex tectonic structure, the undercutting of the slope resulted in occurrence of several different types of instabilities in rock mass and in slope deposits. For this reason there was a need for urgent remedial measures. Individual planar slides in rock mass and smaller rock falls were improved quickly and relatively simply by adequate support systems. More complex geotechnical problem has been reactivated transgressive landslide. The large part of landslide body is saturated by water witch penetrates through slope formation and flows on contact with bedrock. Groundwater flow has direction toward untaken spring, which is situated on the toe of unstable slope. Groundwater has had great impact on strength properties of material, and effective stress quantity on failure surface. There were also activated some debris falls formed as a result of removing a material from a toe of the slopes. The landslide and debris falls were improved with relatively massive retaining structure combinated with reinforcing systems of rock mass in bedrock and complexly drainage systems. All of accepted remedial works were executed using an active design approach. Monitoring of the established network of piezometers, inclinometers and landmarks is been carried out during the remedial works. In this paper we will present descriptions of some phenomena of instability in the Čabranka valley in Croatia occurred during the reconstruction of regional road and designed and performed remedial works. We will also present the concept of accepted active design approach during execute of remedial works on the reactivate landslide.

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.

Prema Crudenu klizište se definira kao pomicanje mase stijena, krhotina ili zemlje niz padinu. Do klizanja tla dolazi kada se poremeti njegova stabilnosti, a mogu je prouzročiti prirodne pojave ili čovjek svojim djelovanjem. Takve pojave klizanja tla su učestale, vrlo opasne te prouzrokuju velike materijalne štete i ljudske žrtve diljem svijeta. Zadatak ovog diplomskog rada je utvrditi kako mjere sanacije utječu na stabilnost klizišta provedbom laboratorijskih ispitivanja umanjenog fizičkog modela klizišta. Ovakvim ispitivanjima dobivamo korisne podatke o klizištima i načinima na koje možemo provoditi sanacije kosina na kojima bi se potencijalno moglo pojaviti klizanje tla. Preko brojnih senzora ugrađenih u model saznajemo na koji se način mijenjaju vlažnost i porni tlakovi u modelu. Temeljem analize tih podataka možemo promatrati razlike u ponašanju modela na kojem su provedene mjere sanacije u odnosu na model na kojem to nije učinjeno., According to Cruden, a landslide is defined as the movement of a mass of rock, debris or soil down a slope. Land slippage occurs when its stability is disturbed, and it can be caused by natural phenomena or by human action. Such occurrences of landslides are frequent, very dangerous and cause great material damage and human casualties all over the world. The task of this thesis is to determine how rehabilitation measures affect the stability of the landslide by conducting laboratory tests of a reduced physical model of the landslide. Through these tests, we get useful information about landslides and the ways in which we can carry out rehabilitation of slopes where landslides could potentially occur. Through numerous sensors built into the model, we find out how humidity and pore pressures change in the model. Based on the analysis of these data, we can observe the differences in the behavior of the model on which rehabilitation measures were implemented compared to the model on which this was not done.

Klizišta se svrstavaju u najopasnije i najčešće geohazarde na svijetu. S obzirom na kompleksnu pojavu klizišta zadatak diplomskog rada je pripomoći razumijevanju i utjecaju pri pojavi klizanja. Izrada umanjenih modela izvodi se na Građevinskom fakultetu u Rijeci što je u sklopu projekta Fizičko modeliranje ponašanja konstrukcija za sanaciju klizišta u uvjetima statičkih i seizmičkih djelovanja. Prikupljanje podataka pri ispitivanjima korisno je za procjenu rizika pri pojavi klizišta kao i odabiru pravovaljane mjere sanacije. Diplomskim radom prikazat će se svi dobiveni rezultati ispitivanja čime će se objasniti pojava nestabilnosti te se ukazati na rad senzora pri mjerenjima s obzirom na opisane komponente unutar priručnika. Utjecaj vlažnosti i porni pritisci dat će zaključke prema kojima se odvija proces destabilizacije kosine., Landslides are classified as the most dangerous and frequent geohazards in the world. Considering the complex occurrence of landslides, the task of the thesis is to help understand and influence the occurrence of landslides. The production of reduced models is carried out at the Faculty of Civil Engineering in Rijeka, which is part of the project Physical modeling of the behavior of structures for the rehabilitation of landslides under the conditions of static and seismic actions. Data collection during tests is useful for risk assessment in the event of a landslide, as well as for the selection of valid remedial measures. The thesis will present all the obtained test results, which will explain the occurrence of instability and indicate the operation of the sensor during measurements with regard to the described components in the manual. The influence of humidity and pore pressures will give conclusions according to which the slope destabilization process takes place.

Stabilnost prirodnih i umjetnih kosina predstavlja jedan od glavnih problema u geotehnici. Najčešći uzroci pojava klizišta su infiltracija oborinske vode i posljedično podizanje razine podzemne vode. Analize stabilnosti kosina provode se zbog utvrđivanja pojava i uzroka nestabilnosti, te dimenzioniranja mjera sanacije. U radu su prikazana dva ispitivanja provedena u laboratoriju za geotehniku na Građevinskom fakultetu u Rijeci u sklopu znanstveno istraživačkog projekta Fizičko modeliranje ponašanja konstrukcija za sanaciju klizišta u uvjetima statičkih i seizmičkih djelovanja (ModLandRemSS), financiranog od strane Hrvatske zaklade za znanost. Prvi model je model kosine izgrađene od sitnozrnastog pijeska u nagibu od 35° i bez mjere sanacije, a u drugi model je ugrađen gravitacijski potporni zid kao mjera sanacije. Oba modela podvrgnuta su sličnim uvjetima umjetne oborine te su tijekom pokusa prikupljani podaci o promjenama pornih pritisaka i vlažnosti tla u modelu pomoću ugrađenih senzora. Dok su za osnovni model bez ugrađenih mjera sanacije zabilježena klizanja i razvoj nestabilnosti od nožice prema vrhu modela, gotovo nikakve značajnije promjene nisu bile vidljive u kosini s ugrađenim potpornim zidom za iste uvjete opterećenja. Rezultati ispitivanja detaljno prikazani u ovom radu korišteni su za provedbu analiza stabilnosti modela., The stability of natural and artificial slopes is one of the main problems in geotechnics. The most common causes of landslides are the infiltration of rainwater and the consequent rise in the groundwater level. The analyzes of the slope stability are carried out to determine the occurrences and causes of instability, and dimensioning of remedial measures. The paper presents two tests carried out in the geotechnical laboratory at the Faculty of Civil Engineering in Rijeka as a part of the scientific research project Physical modelling of landslide remediation constructions behavior under static and seismic actions (ModLandRemSS), financed by the Croatian Science Foundation. The first model is a model of a slope built from fine-grained clean sand at a slope angle of 35° without remedial measures and in the second model has a gravity retaining wall incorporated as a remedial measure. Both models were subjected to similar conditions of artificial precipitation, and data on changes in the pore pressures and soil moisture in the model were collected during the experiment using the built-in sensors. While the basic model without built-in remedial measures, where slide and the development of instability were recorded from the foot towards the top of the model, showed almost no significant changes with respect the model of the slope tested with the retaining wall for the same load conditions. The test results are presented in detail in this paper and are used to perform model stability analyses.

Open image in new window Ash-fall pyroclastic deposits that mantle mountain slopes around the Mount Somma-Vesuvius (Campania, southern Italy) are frequently involved in debris flows under high-intensity and prolonged rainfall, thus representing a principal geohazard for settlements located alongside the footslope areas. In such a geomorphological framework, to understand temporal and spatial hydrological dynamics occurring into ash-fall pyroclastic soil coverings is a key factor for assessing and modelling landslide hazard as well as for setting reliable early warning system. Along with this research focus, since 2011 field monitoring activities were carried out in a test area of the Sarno Mountains to assess hillslope hydrological processes that predispose and lead to slope instability. The analysis of pressure head time series, recorded along four hydrological years (Jan 2011–Dec 2014) in the whole thickness of the ash-fall pyroclastic soil cover, showed a composite temporal variability, from the daily to the seasonal time scales, related to rainfall patterns and evapotranspiration regime as well as to unsaturated flow dynamics. Unsaturated conditions were always observed with pressure head values ranging at the annual scale from about −0.6 m to, and beyond, −20 m. Such a marked hydrological dynamics of the ash-fall pyroclastic soil covers demonstrates the relevant role of antecedent hydrological conditions in predisposing landslide triggering under a single rainfall event. Therefore, results obtained by the proposed approach can be conceived as a fundamental basis to understand hydrological processes at slope scale. Moreover they can be used to set and calibrate hydrological numerical and slope stability models for estimating rainfall thresholds triggering slope instabilities as well as to assess inherent landslide hazard.