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Landslide Detection and Spatial Prediction: Application of Data and Information from Landslide Maps
No full textAbstract The need for landslide maps of wider areas has increased with the understanding that proper planning will considerably decrease the construction and maintenance cost of structures. The main objective of the paper is to present types of data and information on landslides that can be derived from landslide inventory and landslide susceptibility maps and their use for spatial and urban planning. Recent examples of landslide zonation maps from Croatia are given to show the possibility of the derivation of data about landslides by using LIDAR (Light Detection and Ranging) DTM (Digital Terrain Model) for the compilation of historical landslide inventory. The application of data about landslide phenomena is compared with the application of information from landslide susceptibility zonation maps. It is concluded that a multi-level and hierarchical approach is necessary to reach the cost-effectiveness of nationwide production of landside maps for land-use planning
Landslide and Soil Erosion Inventory Mapping Based on High-Resolution Remote Sensing Data: A Case Study from Istria (Croatia)
No full textThe central part of the Istrian Peninsula (Croatia) is the area of the Eocene flysch basin, i.e. “Gray Istria, which is prone to weathering and active geomorphological processes. The high erodibility of the Istrian marls led to the formation of steep barren slopes and badlands exceptionally susceptible to slope movements. This research presents the application of high-resolution remote sensing data, i.e., Light Detection and Ranging (LiDAR) data and orthophoto images, for landform mapping at a large scale (1:500). Visual interpretation of remote sensing data was done for the pilot area (20 km) near City of Buzet to produce detailed inventory maps for implementation in the spatial planning system. There is a lack of detailed inventory maps because systematic mapping was not performed for any part of Istria until the scientific research project (HRZZ IP-2019-04-9900), funded by the Croatian Science Foundation. After preliminary visual interpretation of LiDAR DTM and field verifications, it was concluded that four types of landforms could be mapped, i.e. badlands, gully and combined erosion, unstable slopes and landslides. The research objective is to show the representative examples and potential of direct and unambiguous identification and mapping of small and shallow landslides and soil erosion processes based on the visual interpretation of high-resolution remote sensing data in flysch-type rock
Petrography and geochemistry of Cretaceous bauxites from Jajce, Bosnia and Herzegovina
No full textThe study presents petrographic and compositional data of Late Cretaceous bauxite deposits in the area of Jajce, Bosnia and Herzegovina. Results indicate that bauxites exhibit ooidic to pisodic textures enclosed within a pelitomorfic matrix. Most of the deposits are boehmitic but in some localities, a considerable quantity of diaspore is identified. Hematite is the dominant Fe-mineral, while kaolinite, goethite and calcite are minor. The accessory minerals are represented by anatase, rutile and zircon. Al2O3 content ranges between 54.32–61.05 wt % and is negatively correlated to Fe2O3. Rare earth elements (REE) show variable concentrations, reaching up to 1353 ppm. The chondrite normalized patterns reveal negative Eu anomaly in all and positive Ce anomaly in almost all samples. Ce anomaly shows negative correlation with REE. Bauxites from the Jajce area represent valuable mineral resource with potentially valuable quantities of REE and Sc. Mineralogy and geochemical signature indicate a complex petrogenetic history
Application of the SAP2000 computer programme in the modelling of an underground quarry of dimension stone
No full textA numerical analysis of part of the underground quarry of dimension stone with designed maximum dimensions of the rooms was carried out with the SAP2000 software based on the finite element method. The main objective of the analysis was to examine the preliminary stability and the influence of excavation on the redistribution of stresses in the surrounding rock masses, thus confirming the applicability of the tributary area method. The analytical solution with the tributary area method showed satisfactory agreement with the numerical calculations, and the results of the analytical calculations were on the safe side. The obtained results confirmed the predicted behaviour of the rock mass, which confirms the use of SAP2000 as a general-purpose software for civil engineering in the field of mining. The highest concentrations of stresses and strains are found in the edge areas of the pillars, so their correct design is crucial. The safety factor of the point with the highest stresses was determined and a value of 2.21 was obtained, thus fulfilling the stability condition. As for the influence on the surrounding area, stress changes of less than 10% were determined based on the solutions for the vertical stresses at a distance of 20 m from the underground excavation
The role of slope inclination, doline density and water budget analysis in delineation of complex karst catchment area of Slunjčica River (Croatia)
No full textRadi vrlo visoke prirodne ranjivosti krških vodonosnika, izrazito je važno precizno određivanje slivne površine. U okviru ovog istraživanja razmatran je utjecaj nagiba terena, gustoće vrtača i vodne bilance u procesu razdvajanja složenih krških slivnih područja. Za definiranje hidrogeološke uloge pojedinih litoloških jedinica korištena je kombinacija hidrogeoloških profila s podacima o gustoći vrtača i nagibu terena, dok je za opis propusnosti pojedinih stijenskih jedinica korišten stupanj okšenosti. Za verifikaciju i provjeru izdvojenih slivnih područja korištena je vodna bilanca. Metodologija korištena za utvrđivanje hidrogeološke uloge pojedinog područja i određivanje slivnog područja (rijeka Slunjčica, Hrvatska) prikazana je dijagramom toka. Utvrđeno je da se najveće vrijednosti gustoće vrtača pojavljuju u dijelovima terena s nagibom padina od 0 to 1°, te se smanjuju s povećanjem nagiba padina. Iako rezultati istraživanja potvrđuju da je čak i s malim brojem ulaznih podataka moguće odrediti slivno područje u kršu, potrebno je dodatno naglasiti da analiza gustoće vrtača predstavlja nezamjenjiv alat prilikom istraživanja vezanih za određivanje slivnih područja u kršu
Curves related to the Gergonne point in an isotropic plane
No full textThe notion of the Gergonne point of a triangle in the Euclidean plane is very well known, and the study of them in the isotropic setting has already appeared earlier. In this paper, we give two generalizations of the Gergonne point of a triangle in the isotropic plane, and we study several curves related to them. The first generalization is based on the fact that for the triangle ABC and its contact triangle AiBiCi, there is a pencil of circles such that each circle km from the pencil the lines AAm, BBm, CCm is concurrent at a point Gm, where Am, Bm, Cm are points on km parallel to Ai,Bi,Ci, respectively. To introduce the second generalization of the Gergonne point, we prove that for the triangle ABC, point I and three lines q1,q2,q3 through I there are two points G1,2 such that for the points Q1,Q2,Q3 on q1,q2,q3 with d(I,Q1)=d(I,Q2)=d(I,Q3), the lines AQ1,BQ2 and CQ3 are concurrent at G1,2. We achieve these results by using the standardization of the triangle in the isotropic plane and simple analytical method
Specific energy consumption of material handling by excavator in the quarrying of crushed stone
No full textA hydraulic excavator is widely used in crushed stone quarries to perform many different operations. Previous research on material handling by excavators is most often based on laboratory testing and observation of soil materials and the digging forces in them. These results are very difficult to transfer to fieldwork during the quarrying process. Therefore, in this work, the energy consumption of an excavator while working in typical materials for a crushed stone quarry was investigated. The field measurements were performed on overburden, blasted rock material, boulders, and two different crushed materials. Energy consumption was observed only during the portion of the cycle in which the bucket digs the material. In this way, the energy consumption was mainly related to the properties of the material. The highest energy consumption was found for blasted rock material, lower in overburden, and the lowest for boulders and crushed materials. These results are important for organizing an optimal distribution of machines according to the work tasks in the quarry and ultimately for energy savings
Lithology and porosity distribution of high-porosity sandstone reservoir in North Adriatic using machine learning synthetic well catalogue
No full textReservoir characterization on offshore fields often faces specific challenges due to limited or unevenly distributed well data. The object of this study is the North Adriatic poorly consolidated clastic reservoir characterized by high porosity. The seismic data indicate notable differences in reservoir quality spatially. The only two wells on the field drilled the best reservoir area. Seismic data, seismic reservoir characterization, and accurate integration with scarce well data were crucial. This paper demonstrates how the application of machine learning algorithms, specifically a Deep Forward Neural Network (DFNN), and the incorporation of pseudo-well data into the reservoir characterization process can improve reservoir properties prediction. The methodology involves creating different reservoir porosity and thickness scenarios using pseudo-well data, synthetic pre-stack seismic data generation, seismic inversion, and DFNN utilization to improve porosity prediction. This study also highlights the importance of lithology discrimination in the geological model to better constrain reservoir properties distribution in the entire reservoir volume. Facies probability analysis was utilized to define interdependence between litho–fluid classes established from the well data and acoustic impedance volume. Apart from the field well data, seismic inversion results, and DFNN porosity volume as main inputs, acknowledgments from the neighboring fields also had an important role
Reference seismic crustal model of the Dinarides
No full textContinental collision zones are structurally one of the most heterogeneous areas intermixing various different units within a relatively small space. A good example of this is the Dinarides, a mountain chain situated in the central Mediterranean, where thick carbonates cover older crystalline basement units and remnants of subducted oceanic crust. This is further complicated by the highly variable crustal thickness ranging from 20 to almost 50 km. In terms of spatial extension, this area is relatively small but covers tectonically differentiated domains making, any seismic or geological analysis complex, with significant challenges in areas that lack seismic information on crustal structure. Presently there is no comprehensive 3D crustal model of the Dinarides (and surrounding areas). Using the compilations of previous studies and employing kriging interpolation, we created a vertically and laterally varying crustal model defined on a regular grid for the wider area of the Dinarides, also covering parts of Adriatic Sea and the SW part of the Pannonian Basin. The model is divided by three interfaces, Neogene deposit bottom, carbonate rock complex bottom and Moho discontinuity, with seismic velocities (P and S waves) and density defined at each grid point. To validate the newly derived model, we calculated travel times for an earthquake recorded on several seismic stations in the Dinarides area. The calculated travel times show significant improvement when compared to the simple 1D model used for routine earthquake location in Croatia. The model derived in this work represents the first step towards improving our knowledge of the crustal structure in the complex area of the Dinarides. We hope that the newly assembled model will be useful for all forthcoming studies (e.g., as a starting model for seismic tomography, as a model for earthquake simulations) which require knowledge of the crustal structure
Geotechnical reconnaissance of an extensive cover-collapse sinkhole phenomena of 2020–2021 Petrinja earthquake sequence (Central Croatia)
No full textThis article presents geotechnical reconnaissance data that characterize the formation of 122 new and 49 historical cover-collapse sinkholes within 1.13 km2 area in 12 months following the MW 6.4 earthquake that occurred on 29 December 2020, in Petrinja, Croatia. Data include a geological background, seismic sequence information, sinkhole geometric characteristics, rainfall data, and results of detailed geotechnical subsurface investigation. The sinkhole geometrical features were collected using aerial and satellite imagery, terrestrial lidar, and manual measurements. Soil properties and groundwater levels were obtained from four geotechnical boreholes, accompanied by in situ geotechnical characterization and standard penetration tests (SPTs). Soil parameters were obtained from consolidated undrained conventional triaxial compression, oedometer, soil water retention, and index tests performed on 31 soil samples. Clayey cover, 4–10 m thick, with sporadic gravel lenses overlying cavernous, intensely karstified carbonate rocks, characterizes the sinkhole area. Clays are mostly overconsolidated, with varying degrees of saturation ranging from very small to fully saturated. Seasonal and climate-induced variations in the groundwater table interact with artesian/subartesian karst aquifer, thus affecting the suction and the shear strength. Soil water retention curves (SWRCs) indicate that desaturation is possible for deeper groundwater tables, thus further affecting the effective stress, shear strength, and interparticle tensile forces. Finally, the observed vertical walls that accompanied sinkholes opening can occur in the overconsolidated cohesive cover clay layer with varying degree of saturation. The presented data provide essential geomechanical information necessary to understand the associated sinkhole failure mechanism. This article will help future investigators to perform detailed analyses and provide a background for complementing future sinkhole precursor research. Geotechnical, geological, seismic, and precipitation data generally indicate that the formation of cover-collapse sinkholes in the study area is a consequence of a specific local geological setting but is significantly expedited by earthquake-induced dynamic loading and complemented by multiple hydro-mechanical factors