Development and improvement of geotechnical design methods and application of Eurocode 7

In order to avoid the inequality arising from many and different civil engineering standards, rulebooks etc. present in the EU, academicians and practicioners have initiated voting a decision in 1975 for removing them and replace with set o f harmonized technical rules, known as Eurocodes. They are covering parts from Eurocode 0 to Eurocode 9, among which is Eurocode 7 which is dedicated to geotechnical design. But, its realization, due to different geographical, geological and climate conditions which leaded to development o f different local calculation traditions, was more difficult and complicated than at others Eurocodes. Anyway, in the period between 1981 and 2004 it was working intensively on exceeding the obvious differences, and which produced different format o f this Eurocode. Namely, unlike others where structure designing is pretty clear, there are three design approaches offered in Eurocode 7 and sets o f partial factors which are to be used in them. After accepting Eurocode 7, each state has to decide on two very important decisions which are related exactly on the choice o f design approach according to which designing o f geotechnical structures is going to be performed and to define appropriate partial factors. Theoretical and numerical analyses and verifications are realized in this research for such purposes for spread foundations, slopes and retaining walls, which are most often present geotechnical structures in practice. The successful results have shown that the same principle, based on keeping the similar calculation procedure and same, proved, safety level as now, can also be used for the other geotechnical structures present in Eurocode 7

Choice of Grout Curtain type of dam “Rečani” on Orizarska river – Kočani

In the frames of Preliminary design for choice of dam type for dam “Rečani” on river of Orizarska near Kočani, three types of embankment dams were elaborated. Based on the results from geological, hydrogeological, geotechnical investigations and recommendations of the geotechnical model, possible alternatives of the grout gallery and curtain were designed. Structural and geotechnical analyses were performed for each of the solutions. At the end, total costs of dam construction and grout works were calculated. Comparing all important factors, optimal design of the grout curtain was proposed. The selection of the optimal type of embankment dam and grouting curtain was also done with application of multi-criteria optimization, by applying of the method of compromise programming

Model for GIS landslide database establishment and operation in Republic of Macedonia

Landslides are one of the most damaging and most significant geo-hazards in the Republic ofMacedonia. Due to many reasons landslide data collection in the past have been generally unsystematic. Knowingthat new occurrences are to be expected in future, brief overview on landslide databases in Europe is given and modelfor establishing and operation of national GIS landslide database is proposed in the paper. Model for assignment ofgovernmental body on landslides, along with structure and way of operation of the envisaged database is presented.Formation of this landslide database is the basic step towards better understanding of the landslide hazard in future.This database will enable conditions for selection of most endangered regions and selection of appropriate models forlandslide hazard and risk zonation. As a result, land use planning will become more efficient, and vulnerability ofpeople and goods will be decreased. In this context, some results from recent landslide susceptibility assessment studiesare also presented

Preparation of GIS landslide inventory for the Polog Region

This paper deals with preparation of Geographic Information Systems (GIS) landslide inventoryfor the Polog region. A number of activities were undertaken for this purpose, such as: analysis of own data on landslides, visits of the sites noted in the surveys filled by municipalities, digitizing of landslides from old geological mapsin scale 1:25000, analysis and digitizing of landslides from the archive of the Geological Survey of Macedonia, interviews with employees and retired colleagues from geotechnical companies, analysis of landslides along the channelsof the “Mavrovo” system, visit to the National University in Tetovo and joint site visit, and visits to several geotechnicalcompanies in Macedonia. Since this is the first attempt to create a regional landslide inventory in N. Macedonia, theadopted structure of the inventory is presented in the paper. Moreover, to see what benefits can be gained from theavailability of such inventory some of the most important findings regarding the landslides are presented further. Currently the inventory consists of 136 occurrences, and in time it should be appropriately updated. The main findingsrelated to the distribution and characteristics of the landslides show that future analyses should include preparation oflandslide susceptibility/hazard models both for shallow and deep landslides, as well as for flow-like type of slides. Inthe following stages of investigation, it is planned to analyze a LIDAR (LIght Detection and Ranging) survey that isbeing prepared for the region and incorporate more landslides in the inventory. Also, findings of the InSAR (Interferometric Synthetic Aperture Radar) analysis will be combined with the inventory, which will lead to conclusions on themovement rates of detected sites. The latter two approaches will be presented in future papers

ASSESMENT OF ROCKFALL DITCH EFFECTIVENES BY APPLICATION OF COMPUTER SIMULATIONS, AN PROBABILISTIC APPROACH

Different types of geohazards frequently affect road and railway traffic. Among them, in the case of mountainous terrains, the rockfalls are considered to be most usual. They cause economic losses of different magni-tude, in some cases even loss of human life. In order to improve the management of the rockfall hazard and risk, researchers had been developing many different methodologies for assesment and design of effective control, protection and preparedness measures. One of the approaches is to apply a structural measure along the road/railway line in the form of a rockfall catch ditch at the toe of the rock cuts. Experimental field tests and computer simulations by many authors have investigated the effectiveness of these ditches, with main goal being to design ditches that are as effective as possible. The paper presents application of computer simulation technique coupled with probabilistic analysis. The main idea is to test the effectiveness of rockfall catch ditches with different geometries, by simulating rockfall blocks of different geometrical shapes. Beside variation of the ditch and block geometry, also varied are the height and slope angle of the rock cut. Results from the probabilistic simulations show the different degree of ditch effectiveness in the investigated cases. The approach is considered useful for the goals in the design process, with main benefits being the improved management of the rockfall risk and economical rationalization of cuts design

Preliminary regional landslide susceptibility assessment using limited data

In this paper a heuristic approach for preliminary regional landslide susceptibility assessment using limited amount of data is presented. It is called arbitrary polynomial method and takes into account 5 landslide conditioning parameters: lithology, slope inclination, average annual rainfall, land use and maximum expected seismic intensity. According to the method, in the first stage, a gradation is performed for each of the carefully selected conditioning parameters by assigning so called rating points to the grid cells on which the region is divided. Values of the rating points vary from 0 to 3 and depend on the parameter’s character and importance for landslide development within the region of interest. A so called Total Landslide Susceptibility Rating (TLSR) model is obtained by summing the individual rating points of each parameter and dividing the region into five susceptibility zones according to Jenks natural breaks classification. Verification of the TLSR model is then performed by overlaying the landslide inventory map of the selected region over the prepared susceptibility map. The sensitivity of the model can be additionally tested by multiplying the conditioning parameter’s rating points by sensitivity coefficients. In this way, additional landslide susceptibility models are obtained, named Weighted Total Landslide Susceptibility Rating (WTLSR) models. As a practical example of the method, two TLSR models are presented here for the Polog region in Republic of Macedonia, for return periods of maximum expected seismic intensity for 100 and 500 years. With over 74% of mapped landslides falling in zones of high and very high susceptibility, the results are considered satisfactory for regional scale landslide modelling and are comparable with more advanced quantitative methods. Additional WTLSR models were prepared, and their correlation identified the best model. The presented approach is considered to be very convenient for conducting preliminary regional landslide susceptibility assessments with the ability to fine-tune the results. Due to its simplicity, it can be applied to additional landslide conditioning parameters other than the one presented in the paper, depending on the region of interest and available data sources. It is especially practical for use in developing countries, where various organizational, technical and economic constraints prevent application of more advanced data driven methods. Limitations and restrictions of the approach are also discussed

Einfluss des Anpressdrucks der Grundmauern auf die Projektierung mithilfe des Antwortspektrums

Oslonci i potresno opterećenje za projektiranje konstrukcija obično su matematički izvodi podataka dobivenih iz profila tala sa slobodnom površinom. Ovo istraživanje je vođeno pretpostavkom da pritisak od konstrukcije na tlo može promijeniti rezonantna svojstva tla i tako preusmjeriti projektiranje konstrukcija. Istraživanje je provedeno na setu od 10 stvarnih profila tla; na 21 studiji slučaja i koristeći dvije metode za korekciju profila brzina posmičnih valova s ciljem uključivanja kontaktnog pritiska. Analitički dobiveni rezultati su uspoređeni s pandanima dobivenim iz eksperimenta provedenog u centrifugi.The supports and seismic actions for structural design are usually mathematical derivatives of the data collected from soil profiles with free-field conditions. This study is based on the premise that the pressure exerted by the structure onto the soil can change resonant properties of soil and thus redirect structural design. The research was conducted on a set of 10 real soil profiles, and involves 21 case studies and the use of two methods for correction of shear wave velocity profiles in order to include contact pressure. Analytically obtained results are compared with the corresponding results obtained by means of a centrifuge experimentUnterstützung und Erbebenbelastung für die Projektierung von Konstruktionen sind in der Regel mathematische Ableitungen von Daten, die aus den Bodenprofilen mit freien Oberflächen erhalten werden. Diese Untersuchung basiert auf der Annahme, dass der Druck der Konstruktion auf den Boden die Resonanzeigenschaften des Bodens verändern und somit die Projektierung der Konstruktionen umlenken kann. Die Untersuchung wurde an einem Set von 10 realen Bodenprofilen durchgeführt; anhand von 21 Fallstudien und zwei Methoden werden Scherwellengeschwindigkeitsprofile mit dem Ziel korrigiert, den Anpressdruck zu berücksichtigen. Die analytisch erhaltenen Ergebnisse wurden mit den aus dem Zentrifugenexperiment erhaltenen Gegenstücken verglichen

Estuary fluvial flooding: the example of the watercourse Miljašić jaruga in the town of Nin (Croatia)

The Miljašić jaruga is one of the most important watercourses in Zadar County (Dalmatia, Croatia). The total length of this area is approximately 16 km, with an associated topographic catchment of approximately 191 km2. The downstream portion of the stream is influenced by the sea (estuary). The hydrological regime of the Miljašić jaruga is strongly influenced by climatic features; therefore, for most of the year, there is an outflow of catchment waters, whereas in the summer dry months, the river bed is mostly without outflow. It is also common for extreme precipitation to occur after a long dry period, resulting in sudden increase in water levels and flash floods. One such extreme event occurred on September 11, 2017, when a severe storm followed by heavy rain affected Zadar and its hinterlands. On that occasion, approximately 240 mm/m2 fell in Zadar over a period of 6 h, with an intensity of up to 70 mm/m2/h. Such extreme rainfall activated violent and torrential runoff, flooding, and damage in the entire catchment area of the Miljašić jaruga, particularly in the most downstream part of the basin, in the area of the estuary and the town of Nin. Numerous infrastructural and communal facilities have been damaged, including the Nin Salt Works. This paper presents the hydrological analysis of a flash flood event in the Miljašić jaruga estuary. A hydrological series of 26 and 27 years were compared, whereas the longer series include historical flood, using three distributions: normal, log-normal and Gamma. The relevant hydrological parameters (water levels and flows) used for dimensioning the flood defense system show great variability depending on the available data (time series) and calculation methodology. For example, variation of flow rate reached 41 m3/s for 100-year high waters, that is, from 60 m3/s (n = 26, normal distribution) to 101 m3/s (n = 27, log-normal distribution). In engineering practice, the unreliability of the estimation of statistical quantities should be considered to improve the effectiveness of flood defense systems. The rehabilitation and reconstruction work conducted after a flood on hydrotechnical structures (embankments) in the estuary area is described. In addition, there is a need for adequate water management across the entire basin, such as the construction of retention and barriers, which would increase the level of flood protection in the most downstream parts, i.e., the estuary

Estuary fluvial flooding: the example of the watercourse Miljašić jaruga in the town of Nin (Croatia)

The Miljašić jaruga is one of the most important watercourses in Zadar County (Dalmatia, Croatia). The total length of this area is approximately 16 km, with an associated topographic catchment of approximately 191 km2. The downstream portion of the stream is influenced by the sea (estuary). The hydrological regime of the Miljašić jaruga is strongly influenced by climatic features; therefore, for most of the year, there is an outflow of catchment waters, whereas in the summer dry months, the river bed is mostly without outflow. It is also common for extreme precipitation to occur after a long dry period, resulting in sudden increase in water levels and flash floods. One such extreme event occurred on September 11, 2017, when a severe storm followed by heavy rain affected Zadar and its hinterlands. On that occasion, approximately 240 mm/m2 fell in Zadar over a period of 6 h, with an intensity of up to 70 mm/m2/h. Such extreme rainfall activated violent and torrential runoff, flooding, and damage in the entire catchment area of the Miljašić jaruga, particularly in the most downstream part of the basin, in the area of the estuary and the town of Nin. Numerous infrastructural and communal facilities have been damaged, including the Nin Salt Works. This paper presents the hydrological analysis of a flash flood event in the Miljašić jaruga estuary. A hydrological series of 26 and 27 years were compared, whereas the longer series include historical flood, using three distributions: normal, log-normal and Gamma. The relevant hydrological parameters (water levels and flows) used for dimensioning the flood defense system show great variability depending on the available data (time series) and calculation methodology. For example, variation of flow rate reached 41 m3/s for 100-year high waters, that is, from 60 m3/s (n = 26, normal distribution) to 101 m3/s (n = 27, log-normal distribution). In engineering practice, the unreliability of the estimation of statistical quantities should be considered to improve the effectiveness of flood defense systems. The rehabilitation and reconstruction work conducted after a flood on hydrotechnical structures (embankments) in the estuary area is described. In addition, there is a need for adequate water management across the entire basin, such as the construction of retention and barriers, which would increase the level of flood protection in the most downstream parts, i.e., the estuary