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The small-scale physical model platform was developed as part of a four-year research project, "Physical modeling of landslide remediation constructions' behaviour under static and seismic actions, " to investigate the behaviour of slopes built of different materials with and without remedial measures under the influence of rainfall and earthquake. As in real landslides, the observation of a physical model consisted of a geotechnical and a geodetic monitoring system. In this paper, the behaviour of clay-like slopes during 1g artificial rainfall, with and without remedial measures will be described. Complex remedial measures included deep trench drains which reduced pore water pressure, and pile wall with head beam made with 3D printer, which increased shear resistance at the sliding surface. At the same rainfall intensities, the clay-like slope collapsed, while the slope supported with a pile wall at the slope foot remained stable. The results of the photogrammetric equipment and the complex sensor network measurements within a slope are presented and discussed, helping us to understand the different behaviour of slopes with and without remedial measures.

Small-scale physical models of landslides triggered by rainfall and seismic conditions provide a good insight into the initiation and progression of full-scale landslides in nature. In order to track and document the displacements on the surface of the small-scale model, a digital image correlation-based optical measuring system with high-speed cameras is used here. Each model is prepared for the optical measurements by adding specially chosen marker points (pins) that are monitored by a pair of high-speed cameras during each experiment. An additional set of non-high- speed cameras with higher resolution is used to monitor the deformation field on a selected smaller part of the model. This enables to obtain the 3D displacements and velocities of each marker point in order to detect any movement or crack opening on the surface both visually and accurately from the optical measurement results. The described system and established measurement procedure are advantageous as they provide the 3D displacement and velocity data for a large number of points on the surface with less equipment than conventional contact measurement methods. The collected data, in combination with other monitoring sensors, allow the observation of landslide initiation and the analysis of landslide evolution in all parts of the model slope during the sliding process. In this paper we present the measurement procedure and the results obtained optically in selected small-scale experiments.

Physical modelling of landslides using scaled landslide models behavior began in 1970s in Japan at a scaled natural slope physical model. The laboratory experiments of landslide behavior in a scaled physical model (also called flume or flume test) started in 1980s and 1990s in Canada, Japan and Australia under 1g conditions. The main purpose of the landslide physical modelling in the last 25 years was research of initiation, motion and accumulation of fast flow like landslides caused by infiltration of water in a slope. In October 2018, at the Faculty of Civil Engineering University of Rijeka, started a four-year research Project Physical modelling of landslide remediation constructions behavior under static and seismic actions, funded by the Croatian Science Foundation. The main Project aim is the modelling of landslide remedial constructions’ behavior in physical models of scaled landslides in static (rainfall triggered landslides) and seismic conditions (earthquake triggered landslides) and their combination under 1g conditions. In this manuscript we will present the preliminary results obtained in landslide initiation test of a sandy slope (constructed of 0-1.0 mm the Drava River sand) exposed to an artificial rain typical for local conditions in Croatia by rainfall simulator. The results of landslide development were monitored by observation of volumetric water content and pore water pressure as well as by of surface displacement by structure from motion (SfM) surface observation displacement monitoring inside the model displaced mass. In this paper the preliminary results of provided test will be presented related to initiation and development of the observed instability of the sandy slope model.

The Špičunak Landslide is a deep-seated slowmoving landslide causing damages on the pavement of the state road D3 near the Lokve settlement in the Gorski Kotar region, Croatia, during the last 50 years. The landslide was formed at the contact of Permian shales and Jurrasic limestone and dolomites. The length of the landslide is 70 m, the width is 85 m and the depth of sliding surface is 20 m. Due to deformations on the state and local road as well as on the embankment stone lining between them, it was necessary to perform remediation measures. Field investigations were executed as well as monitoring of displacement and ground water level. Based on the results of field investigations, the remedial measures were designed to stop further sliding and to increase general stability of the slope. The complex remedial measures design includes pile wall anchored in the head with pre-stressed geotechnical anchors positioned below the state road, concrete grid construction and self- drilling bolts on the embankment stone linings, in combination with bored and trench drains below the road construction and in the landslide foot. The stability back analysis as well as stability analysis for the designed remediation measures were carried out. Monitoring of the landslide during and after remediation using piezometers and inclinometers is also included in design. This paper presents the case study of the Špičunak Landslide, results of stability analysis and designed measures that will be used in landslide remediation planned to be conducted during the autumn 2019.

U ovom doktorskom radu prikazani su rezultati istraživanja utjecaja trošenja na rezidualnu posmičnu čvrstoću i postojanost sitnozrnastih litoloških članova flišne stijenske mase na području sjeverne Istre, doline Rječine i Vinodolske doline. Nekompetentni, sitnozrnasti litološki članovi flišnog kompleksa trošenjem značajno mijenjaju fizičko mehaničke značajke. U naslagama fliša cesta je pojava klizišta pri ćemu se klizna ploha formira ili na kontaktu pokrivača i flišne stijene ili kroz trošne slojeve flišne stijenske mase. Uslijed klizanja dolazi do usitnjavanja stijenske mase na kliznoj plohi, a čvrstoća materijala uslijed nastalih deformacija pada s vršnih na rezidualne vrijednosti. Za reaktiviranje umirenih klizišta po istim kliznim plohama mjerodavne su rezidualne vrijednosti posmične čvrstoće materijala na istima. Utjecaj trošenja na vrijednosti rezidualne posmične čvrstoće sitnozrastih litoloških članova iz naslaga fliša proveden je laboratorijskim ispitivanjima uzoraka različitih stupnjeva trošnosti uređajem za izravno smicanje i prstenasto smicanje. Također su ispitane jednoosna tlačna čvrstoća te postojanost uzoraka sitnozrnastih litoloških članova fliša različitih stupnjeva trošnosti. Određene su promjene mineralnog sastava istih sitnozrastih litoloških clanova fliša različite trošnosti nastalih u procesu trošenja. Provedene su numeričke simulacije reaktiviranja klizišta Krbavčići II u sjevernoj Istri i klizišta Valići u dolini Rječine korištenjem rezidualnih parametara čvrstoće za različite stupnjeve trošnosti sitnozrnastih litoloških članova fliša. Pokazano je da trošenje sitnozrnastih litoloških članova fliša ima značajan utjecaj na pad rezidualne posmične čvrstoće te da trošenje ovih materijala utječe na reaktiviranje umirenih klizišta u flišnoj stijenskoj masi., Investigation results of the influence of weathering process on the residual shear strength and durability of fine grained lithological flysch components in the area of north Istria, Rječina Valley and Vinodol Valley are presented in this doctoral theises. Physical and mechanical properties of incompetent, fine grained flysch lithoilogcal members significantly change due to weathering. Landslide occurrences in flysch deposits are frequent and slip surface is formed at the contact of surficial deposits and flysch rock mass or inside the weathered flysch rock mass. Rock mass defragmentation at the slip surface occurs due to sliding and shear strength decreases from peak to residual values thorugh occured displacements. These residual strength values of the slip surface material are competent for the dormant landslide reactivation along the same slip surface. Weathering effect on the residual shear strength values of fine grained lithological flysch components are investigated by laboratory tests on samples of different weathering grades in direct shear and ring shear apparatus. Also uniaxial compressive strenth and durability of fine grained lithological flysch rock mass samples with different weathering grades are investigated. Mineralogical composition of the same fine grained lithological flysch components of different weathering grades is determined. Numerical simulation of the Krbavčići II landslide in north Istria and Valići landslide in the Rječina Valley reactivation are conducted with residual strength parameters of different weathering grades of fine grained lithological flysch components. It is proved that weathering process has significant effect on the residual shear strength decrease of fine grained lithological flysch components and that weathering of those materials causes the dormant landslide reactivation in the flysch rock mass.

Klizište Gradišće se nalazi u naselju Gradišće, oko 3 km zapadno od grada Samobora, u Zagrebačkoj županiji. Predmetno klizište pokrenuto je sredinom travnja 2013. godine, nakon razdoblja nadprosječnih oborina i neuobičajeno velikih količina snijega u zimskom razdoblju, nakon kojeg je u kontinentalnom dijelu Hrvatske zabilježeno preko 900 pojava nestabilnosti. Klizište Gradišće predstavlja rotacijsko klizanje po dvije klizne plohe u inženjerskom tlu, uzrokovano kombinacijom hidroloških neprilika, prisutnosti materijala srednje do niske plastičnosti i trošne, raspucane osnovne stijene. U sklopu istražnih radova provedena su istražna bušenja, detaljno inženjerskogeološko kartiranje i laboratorijsko ispitivanje uzoraka tla i trošne stijene. U geotehničkom smislu, predmetna lokacija sastoji se od pokrivača (nasip, koluvij, deluvij, trošni siltiti i šejlovi) koji ima značajke inženjerskog tla i osnovne stijene (siltiti i šejlovi) u podlozi. Prosječan nagib terena na dijelu padine na kojemu je nastalo klizište je 30˚. Predmetno klizište se nalazi u gornjem dijelu padine, pri čemu je na lokalnoj cesti nastalo oštećenje uslijed denivelacije gornjeg dijela pokrenute mase po glavnoj pukotini. U radu je prikazan opis i nastanak klizišta Gradišće, rezultati provedenih istražnih radova te analize dvaju predloženih varijantnih rješenja sanacije klizišta: izvedbom armiranog nasipa u stopi klizišta i gabionskog potpornogrnog zida ispod lokalne ceste te pilotske stijene kao drugog varijantnog rješenja.

Zbornik radova s međunarodnog znanstvenog simpozija 5th Regional Symposium on Landslides in the Adriatic-Balkan Region (ReSyLAB) Landslide Modelling & Applications održanog u Rijeci od 23. do 26. ožujka 2022. godine na Građevinskom fakultetu Sveučilišta u Rijeci u organizaciji Hrvatske grupe za klizišta, Građevinskog fakulteta Sveučilišta u Rijeci te Rudarsko-geološko-naftnog fakulteta Sveučilišta u Zagrebu.

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.

130 125 М30 М33 Landslides are one of the most often natural disasters that have an extensive impact on society including loss of life, destruction of infrastructure and properties, damage to land and loss of natural resources. Landslide losses can significantly vary and they depend on a variety of different criteria such as the size and type of landslide, lithological setting of terrain, the terrain slope gradient, the quality of materials used for construction, and the construction typology. Damage from landslides is usually characterized as either direct or indirect and in most questionnaires only the data referring to the direct damage is collected. In this paper, a landslide damage questionnaire that can be used for landslide damage characterization and determination of landslide hazard and risk in urban areas is proposed. The questionnaire contains 11 groups of questions that include all necessary fields for gathering the data which is essential for both landslide hazard and risk estimation. It was used as an inventory landslide damage form in suburban housings which usually occupy larger land plots, while objects built on such plots are mostly houses for an individual living or ancillary type.

This paper presents a result of landslide inventory mapping at the Bednja Municipality and Lepoglava City study area in Hrvatsko Zagorje region, NW Croatia. The landslides were interpreted from the high resolution (30 cm) digital elevation model (DEM) and its derivatives (slope and contour map, hillshade). The DEM was interpolated from the point cloud obtained by airborne laser scanning undertaken in spring 2020. In the study area of 20.22 km2, the total number of interpreted landslides is 912, making the average density of 45.1 ls/km2. The average size of the recorded landslides is 448 m2. According to the spatial plans, most of the studied area is covered by forests, agricultural areas, pastures, and artificial areas. The highest density of landslides is also in the forest areas, while the lowest is in the artificial areas. Furthermore, almost 64% of the mapped landslides are located within 50 m of the roads, and more than 39% of the mapped landslides are located within 100 m of the buildings and residential houses. Due to the level of detail provided and its completeness, the presented landside inventory map is an important tool for risk management at the local level because it gives detailed information necessary for risk evaluation as well as to decide about feasible options for risk mitigation, e.g., stabilisation measures vs relocation of the development to a more favourable location.

Rockfalls are common in hilly and mountainous areas, especially along roads with engineered slopes and cuts. Such is the case for most of the state and local road routes in Central, Serbia, which was the subject in this case study. A road network of 276 km covering roughly 1700 km2 bewteen the cities of Kraljevo, Čačak and Ivanjica is presented. Assessing of such wide areas needs to be conducted from large to site-specific scale, i.e., using GIS spatial tools and 2D-3D stability models, respectively. The regional scale of assessment using GIS tools was in focus. The primary input was the Digital Terrain Model, obtained from open data ALOS mission at 12.5 m resolution, as well as appropriate sheets of geological maps at 100k scale. The first step was to delineate areas that can host unstable blocks by inspecting planar sliding kinematic condition against available data. These included raster data (slope angle and azimuth) but also, point-based data (discontinuities’ strike, dip and friction angle) which had to be estimated or interpolated across the area by various GIS operations. In total, there were nearly 5000 potential detachments delineated. Further step was to run the rockfall simulation by using these detachment zones as initiation sources in a simple kinetic model CONEFALL, standalone software. The output model simulated several thousands of rockfalls, with various runout distance (

The objective of this study is a presentation of the landslide susceptibility assessment on a national scale for the Republic of Croatia using a heuristic approach. The effects of controlling factors on landslide susceptibility were estimated using the Fuzzy logic approach based on a multiclass overlay of landslide predictor maps. The predictor set relates to topographic variables, geomorphological factors, geology factors, and land cover. The selection of relevant landslide factors and the final landslide susceptibility assessment depends on subjective factors, such as researcher knowledge of the study area, respectively knowledge of different landslides types and processes in the study area, etc. For these reasons, it was necessary to verify the final landslide susceptibility map with data on known landslides. During the last few years, the scientists from the Faculty of Mining, Geology and Petroleum Engineering in Zagreb were systematically collected data on landslides, and the database of 2, 186 landslides with the exact location of the occurrence was conducted. The Area Under the Receiver Operating Characteristic Curve (AUROC) was used to validate derived landslide susceptibility maps and select the final one for further classification into three susceptibility zones. With over 90% of mapped landslides falling in high and very high susceptibility zones, the results are considered satisfactory for national scale landslide modeling. The landslide susceptibility map of Croatia was created to give a general overview of problem areas for an entire country, and it can be used to inform national policymakers and the general public. The analysis showed that approximately 20% of the area of Croatia is potentially prone to sliding. Particularly landslide-prone areas in Croatia are lowlands and hills in the Pannonian Basin, the hills of the Istrian Peninsula, and isolated narrow valleys in the Dinarides, such as Rječina River Valley and Vinodol Valley in Primorje.

Landslide maps produced by LiDAR (Light Detection and Ranging) are very clear and detailed representation of the phenomena and in many cases reveal evidence of past landslides that are virtually invisible by other detection techniques due to vegetation cover. Over the last decade, airborne laser scanning (ALS) has been made available and has been used to identify and map landslide. LiDAR elevation data prove particularly effective for mapping of small and shallow landslides in areas that are partially or completely covered by dense vegetation that are difficult or impossible to identify using conventional identification techniques. The first topic covered in the talk is landslide detection and mapping using very high-resolution LiDAR DTM to obtain complete historical inventories of shallow soil slides. Few examples of landslide inventory maps from different geomorphological environment of the Republic of Croatia will be presented to show typical landslide distribution. For landslide spatial prediction, the talk focuses on the results of landslide susceptibility modelling and zonation performed for a range of coverages, starting with the largest encompassing whole territory of Croatia. Landslide susceptibility zonation was also performed for areas of two counties (Primorsko-Goranska County and Karlovac County) and few smaller pilot areas of cities and municipalities in the Pannonian Basin and in External Dinarides. The main objective of presented susceptibility zoning in different scales (national, regional and local scale) is to enable analysis of usefulness and reliability of map information (i.e., spatial distributions and rating of the terrain units according to their landslide propensity) for application in physical and urban planning. The needs of the decision-makers, planners and other stakeholders involved in landslide risk prevention are analyzed through the series of round-table discussions organized in Croatia in the framework of the project of applied research PRI- MJER (KK.05.1.1.02.0020). The ultimate goal is to create maps depicting information about landslides tailored according to needs of the system of physical planning in Croatia (particularly land use planning), encompassing local and regional level, harmonized at the national level. The research of the mapping methodologies is part of the project “Methodology development for landslide susceptibility assessment for land-use planning based on LiDAR technology, LandSlidePlan” (HRZZ IP-2019-04-9900) fully supported by Croatian Science Foundation.

An innovative technique for detailed landslide inventory mapping is airborne laser scanning and LiDAR-derived DTMs in high resolution. LiDAR data used in this study was obtained in the framework of the “Methodology development for landslide susceptibility assessment for land use planning based on LiDAR technology (LandSlidePlan IP-2019- 04-9900)” project fully supported by the Croatian Science Foundation. To select the optimal digital terrain model (DTM) for landslide delineation, quantitative and qualitative assessments were done individually for three landslides. The quantitative assessment included a comparison of minimum, maximum, mean, and standard deviation values of DTMs derived by using four interpolation methods (Kriging, IDW, Natural Neighbor, and ANUDEM) in six raster resolutions (0.15, 0.3, 0.5, 1, 2, and 5 m). Furthermore, by comparing point cloud LiDAR data and interpolated DTMs elevation values, the mean-absolute-error difference (MAE) and root-mean-square-error (RMSE) were calculated. Hillshade, roughness, and curvature morphometric maps were derived for 24 DTMs per landslide, resulting in the qualitative assessment of 216 different morphometric maps. The quantitative assessment showed minimum and negligible differences between DTMs for landslide areas ; therefore, the qualitative assessment prioritised determining the optimal DTM for deriving morphometric maps needed for landslide delineation. Based on visual interpretability of landslide parts (i.e. crown, ridges, and toe) and the terrain quality (i.e. expressed details, irregularities, and blurriness) on the derived morphometric maps, the LiDAR DTM derived using the Kriging method in 0.3 m resolution was selected for landslide inventory mapping in further studies.

Physical modelling of landslides by analysing the behaviour of small-scale landslide models subjected to artificial rainfall can be divided into modelling under 1g conditions and under increased acceleration (n times gravity) in a centrifuge. In this paper, the landslide initiation, progression, and deposition caused by artificial rainfall in three small-scale models built with sand or sand-kaolin mixtures at the same slope angle will be described. The evolution of landslides is monitored by observation of volumetric water content, matric suction, and pore water pressure, as well as by monitoring slope deformations and failure development. Analysis of the factors affecting the landslide initiation, propagation and their relationship to the slope material, the infiltration process, and the overall resistance of the soil in a slope in terms of soil strength, effective pressure and the contribution of matric suction in the unsaturated part of the slope will be discussed. The main observations from the results of the tests carried out in relation to the initiation and development of the observed instabilities of sandy and clayey slopes are given.

Klizišta spadaju u najvažnije, najopasnije, a ujedno i najčešće geohazarde na svijetu. Zadatak ovog diplomskog rada je provedba laboratorijskog ispitivanja umanjenog modela klizišta koje je simulirano kišom. Ispitivanje se provodi na Građevinskom fakultetu Sveučilišta u Rijeci u sklopu projekta Fizičko modeliranje ponašanja konstrukcija za sanaciju klizišta u uvjetima statičkih i seizmičkih djelovanja (ModLandRemSS). Osim što je znanstveno korisno, prikupljanje podataka o klizištima korisno je i za procjenu opasnosti i rizika od pojave klizišta. Izbor mjerne opreme i tehnike u umanjenom statičkom modelu klizišta temelji se na pozitivnim saznanjima iz prakse vezanim za upotrebu istih na stvarnim klizištima. Diplomski rad daje uvid na utjecaj vlažnosti i pornih pritisaka na destabilizaciju kosine i prikazuje zaključke koji su uslijedili iz analiza rezultata dobivenih iz podataka sa mjernih uređaja., Landslides are among the most important, most dangerous, and at the same time the most common geohazards in the world. The task of this master's thesis is to conduct a laboratory test of a scale model of a landslide simulated by rain. The test is carried out at the Faculty of Civil Engineering, University of Rijeka as part of the project Physical modeling of the behavior of structures for landslide remediation in the conditions of static and seismic actions (ModLandRemSS). In addition to being scientifically useful, the collection of landslide data is also useful for assessing the hazards and risks of landslides. The choice of measuring equipment and techniques in a reduced static model of landslides is based on positive knowledge from practice related to their use on actual landslides. The thesis gives an insight into the influence of moisture and pore pressures on the destabilization of the slope and presents the conclusions that followed from the analysis of the results obtained from the data from the measuring devices.

Factors primary controlling rainfall-induced slope failures are both rainfall characteristics and soil properties. Rainfall causes a transient infiltration process through the unsaturated part of the slope which affects sloping material by increasing the moisture content and pore-water pressure, changing the effective stress and hydro-mechanical properties of the soil. To study the physical process of rainfall infiltration and how it affects the slope stability state, the dependency between water retention properties, hydraulic permeability, shear strength properties and the water content or negative pore-water pressures existing above the phreatic surface have to be known. Unlike for the shallow-type landslides, very few studies were performed for the case of deep-seated landslides built of material with relatively low hydraulic conductivity. This kind of studies were never performed for landslides occurring in flysch deposits. This study presents the results of different field investigations, laboratory tests, and numerical activities that were performed to build up a numerical model capable to determine the influence of rainfall infiltration process on slope stability state through time. Undisturbed samples of the residual soil from a flysch rock mass were used to perform different laboratory tests in saturated and unsaturated conditions, aimed to provide an advanced hydro-mechanical characterization of the soil behavior under negative pore-water pressure. For the first time, the water retention curves, hydraulic conductivity functions, and unsaturated shear strength characteristics of the investigated soil were determined. Simulation results showed that rainfall duration, instead of intensity, is the crucial factor causing the landslide instability. Results suggest that only about 8 mm of rainfall can infiltrate into the slope during a day. The shear strength component associated with the negative pore-water pressure was found to have a negligible influence on the slope stability at the time of failure since positive pore-water pressure exists along the entire sliding surface. However, it is the unsaturated zone with specific hydraulic features that delay the landslide triggering event. Reduced hydraulic permeability and retention capacity of the soil between the phreatic line and slope surface are factors that postpone build-up of positive pore-water pressure along the sliding surface and enable the slope to remain stable during a long-lasting heavy precipitation., Klizišta uzrokovana oborinama učestalo se događaju diljem svijeta u različitim klimatskim, geološkim i topografskim uvjetima. Rastući broj studija provedenih unazad dva desetljeća ukazuje kako promjene značajki oborina, vezano uz moguće globalne klimatske promjene, mogu dodatno povećati učestalost nastanka klizišta. Uz značajke oborina, karakteristike tla drugi su faktor od krucijalne važnosti za nastanak klizišta uzrokovanih oborinama. Ovisno o odnosu intenziteta kiše i hidrauličkih značajki materijala koji sačinjavaju površinski dio padine, infiltracija oborine u kosinu tijekom vremena odvija se kao nestacionarni proces pri kojem dolazio do promjene vlažnost tla i preraspodjele pornih pritisaka unutar nesaturirane zone geotehničkog presjeka. Pritom najvažniji utjecaj na količinu i brzinu infiltracije, promjenu efektivnih naprezanja i mogući pad čvrstoće materijala imaju hidrauličke i mehaničke značajke tla. Kako bi se riješila jednadžba koja opisuje tečenja vode kroz nesaturirano tlo u vremenu i kvantificirao utjecaj oborine na stanje stabilnosti kosine, potrebno je poznavati funkcije značajki tla u nesaturiranim uvjetima: retencijsku krivulju, funkciju hidrauličke propusnosti te odnos između značajki čvrstoće i vlažnosti tla ili negativnih pornih pritisaka. Matrična sukcija je termin koji se u mehanici nesaturiranih tala najčešće koristi za negativni porni pritisak. Za razliku od plitkih klizišta u materijalima veće propusnosti, studije u kojima se proučava utjecaj nestacionarnog procesa infiltracije oborina na stabilnost dubokih klizišta izgrađenih od materijala relativno niske propusnosti vrlo su rijetke. Prethodna istraživanja klizišta u naslagama fliša u dolini Rječine bavila su se prvenstveno porastom pozitivnih pornih pritisaka uslijed dugotrajnih oborina i utjecajem procesa trošenja flišne stijenske mase na fizičko-mehaničke značajke tla. Pritom je utjecaj dugotrajnih oborina uzet u obzir u analizama stabilnosti jednostavnim podizanje razine podzemne vode (vrlo često i do površine terena), čime se smanjuju efektivna naprezanja i reducira posmična čvrstoća materijala duž klizne plohe. Budući da u ovoj vrsti analiza vrijeme nije jedna od varijabli, distribuciju pornih pritisaka i stabilnost kosine nije moguće analizirati u vremenu. Također, pretpostavlja se da je materijal ispod razine podzemne vode potpuno saturiran, odnosno potpuno suh iznad te razine. Utjecaj matrične sukcije unutar nesaturirane zone geotehničkog presjeka se zanemaruje, kao i svi efekti na hidro-mehaničke značajke tla. Kako bi se, po prvi puta u slučaju istraživanog materijala i predmetnog područja, aplicirali principi nesaturirane mehanike tla na nastanak klizišta uzrokovanih oborinama, provedene su brojne terenske i laboratorijske aktivnosti. Dva osnovna razloga zbog kojih je klizište Valići odabrano kao pilot područje za provedbu istraživanja su prisutnost rezidualnog tla u površinsko dijelu padine za koje je primijećeno značajno isušivanje tijekom sušnih ljetnih mjeseci, te činjenica da su reaktivaciji klizišta u veljači 2014. godine prethodile višemjesečne intenzivne oborine. Neporemećeni uzorci tla uzeti s površinskog dijela klizišta korišteni su za određivanje hidro-mehaničkih značajki tla u nesaturiranim uvjetima. Različitim tehnikama mjerenja i korištenjem ukupno šest laboratorijskih uređaja, određene su retencijske krivulje za proces adsorpcije i desorpcije pri različitim vertikalnim naprezanjima. Metodom nelinearne regresije određeni su parametri najčešće korištenih jednadžbi za opis retencijskih funkcija. Mjerenja hidrauličke propusnosti u saturiranim i nesaturiranim uvjetima, u kombinaciji s retencijskim krivuljama omogućili su definiranje funkcije propusnosti tla u nesaturiranim uvjetima. Time je definirana zavisnost hidrauličke propusnosti materijala od matrične sukcije ili vlažnosti tla. Korištenjem modificiranih uređaja za direktno smicanje tla baziranih na principu translatiranih osi, određen je utjecaj matrične sukcije na značajke čvrstoće tla. Definirane funkcije značajki tla u nesaturiranim uvjetima i rezultati terenskih mjerenja iskorišteni su za definiranje dvodimenzionalnog numeričkog modela kojim je moguće simulirati nestacionarni proces infiltracije oborina u kosinu, te odrediti utjecaj ovog procesa na stanje stabilnosti kosine u vremenu. Kako se parcijalna diferencijalna jednadžba tečenja vode kroz nesaturirano tlo rješava u prostoru i vremenu, pri čemu nelinearnost jednadžbe proizlazi iz nelinearnog odnosa materijalnih značajki i matrične sukcije, rješavanje iste najčešće podrazumijeva iterativne postupke i upotrebu numeričkih metoda. Komercijalno dostupni program SEEP/W (GEO-SLOPE International, Ltd.) baziran na metodi konačnih elemenata korišten je za rješavanje problema infiltracije oborina u kosinu korištenjem realnih ili umjetno generiranih zapisa oborina. Distribucije pornih pritisaka izračunate za različite vremenske trenutke integrirane su u program koji implementira metodu analize granične ravnoteže SLOPE/W (GEO-SLOPE International, Ltd.) kako bi se za svaki od proračunatih profila raspodjele pornih pritisaka izračunao faktor sigurnosti kosine. Time je utvrđena vremenska promjena stanja stabilnosti kosine izgrađene u naslagama fliša, uzimanjem u obzir različitih inicijalnih i rubnih uvjeta. Rezultati analiza potvrdili su dugotrajnost oborina kao presudan faktor za nastanak nestabilnosti, dok ekstremne količine oborina u kraćem vremenskom periodu rezultiraju značajnim površinskim otjecanjem. Čak i kada su mjereni intenziteti u periodu od rujna do veljače 2014. godine reducirani za 50 posto, rezultati analiza ukazuju kako se na dan reaktivacije kosina nalazi u stanju marginalne stabilnosti. Iako komponenta posmične čvrstoće povezana s matričnom sukcijom u trenutku sloma nema utjecaja na stabilnost kosine, utvrđeno je kako upravo nesaturirana zona geotehničkog presjeka, sa svojim specifičnim hidrauličkim značajkama, odgađa gubitak stabilnosti kosine pri ekstremnim oborinama. U tom smislu, smanjena hidraulička propusnost i retencijski kapacitet nestaturirane zone s negativnim pornim pritiscima, faktori su koji usporavaju porast pornih pritisaka duž klizne plohe i osiguravaju stabilnost kosine tijekom dugotrajnih oborina.