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Kavur B.,Institut IGH d.d. | Vrkljan I.,Institut IGH d.d. | Zelic B.K.,Rudarsko geolosko naftni Fakultet Sveucilista u Zagrebu
Gradjevinar | Year: 2011

The paper starts with assertion that, in order to make a quantitative description of expansive soil behaviour, it is indispensable to determine its hydraulic properties: water retention curves and changes in volume, and the hydraulic conductivity function. Experimental and analytic procedures that were used to determine these properties of the studied soil are described. Initially saturated specimens of expansive soil were subjected to drying. The drying tests were successfully simulated via numerical model, based on the estimated properties of material.

Perkovic A.,INA Industrija Nafte D.d | Perkovic D.,Rudarsko geolosko naftni Fakultet Sveucilista U Zagrebu
Rudarsko Geolosko Naftni Zbornik | Year: 2010

Everyday procedures carried out in petrophysical laboratory can be defined as a complete cycle of business processes. Sample handling process is one of the most significant and demanding procedures. It starts with sample receiving in laboratory and then subsequently, series of analyses and measurements are carrying out resulting in petrophysical parameters. Sample handling process ends with sample storage and archiving of obtained measurement data. Process model is used for description of repeating activities. Sample handling process is presented by graphical method and use of eEPC diagram (extended Event-Driven Process Chain) which describe process based on events. Created process model jointly binds static laboratory resources (measuring instruments, computers and data), speeds up process with increasing the user's efficiency and with, improvements of data and information exchange. Besides flow of activity, model of data sample handling includes information about system components (laboratory equipment and software applications) that carry out activities. Described model, with minor modifications and adaptations, can be used in any laboratory that is dealing with, samples.

Dobrilovic I.,Geo eko D.o.o | Gulam V.,Hrvatska Hrvatski Geoloski Institute | Hrzenjak P.,Rudarsko geolosko naftni Fakultet Sveucilista U Zagrebu
Rudarsko Geolosko Naftni Zbornik | Year: 2010

The review of index testing methods with detailed observations on the application of Schmidt rebound hardness and point load strength index in mechanical properties estimations of intact rock material is given in this paper. The results of conducted testing in determining applicability of the above-mentioned testing methods for the estimations of uniaxial compressive strength, elasticity modulus, tensile strength and flexural strength for three characteristic types of limestone from the roof layers of "Korenić i" deposit are also presented.

Klanfar M.,Rudarsko geolosko naftni fakultet Sveucilista u Zagrebu | Vrkljan D.,Rudarsko geolosko naftni fakultet Sveucilista u Zagrebu | Loncaric M.,Stjepana Radica 65
Rudarsko Geolosko Naftni Zbornik | Year: 2015

 During excavation of the Mala Kapela tunnel, measurements of harmful gases concentration, ventilation parameters and microclimatic parameters were performed. Measurements were done in 17 occasions during period of 16 months, along the advance of the tunnel excavation. Consequently, large amount of data was obtained, in different tunnel chainages, ventilation ducts length, and in different work operations during the excavation. Main sources of harmful gases during tunnel excavation are explosives and diesel equipment. The concentration of the same mainly depends on explosive charge and overall diesel equipment power, present at the excavation face of the tunnel. Continuous measurements of the concentration of carbon monoxide (CO) and dioxide (CO2), and nitrogen oxide (NO) and dioxide (NO2) was performed during drilling, blasting, and loading and haulage operations. Measurements were done in 45 cases in total. Recorded data was analysed, where peak concentrations were joined to corresponding operation and the tunnel chainage. Regulations on threshold limit values were used to determine if concentrations rise above the permissible ones. In case they do, the time required for dilution of gases below permissible concentration was noted. Typically, concentrations of all measured gases rise rapidly after blasting. Afterwards, ventilation system acts to dilute them and maintain them relatively constant until the end of loading and haulage. According to measurements in this research, highest concentrations and longest time of dilution were found after blasting. At the same time, concentration of all measured gases exceeds permissible values. Carbon monoxide is found to exceed permissible values during all work operations. It shows most frequent transgression above the limit (in 33 to 100% of cases) and highest time of dilution (up to 40 min). Air supply to the excavation face was measured in 25 cases. It was correlated to the length of ventilation ducts, as the tunnel excavation advances. Results show the trend of air flow drop of 0,3 to 1,2 m3/s per 100m of duct length, with average value of 0,7 m3/s. In accordance with air flow drop, higher peak concentrations and longer time of dilution was observed for drilling and blasting operations. Conversely, lower concentrations and shorter time of dilution were found for loading and haulage operation. This could be attributed to longer truck cycle as excavation advances, thus less diesel units are present in proximity of the excavation face. Measured data on microclimatic parameters was correlated to season changes, distance form tunnel entrance and mutually. Air temperature was measured in 8 cases, along the tunnel and outside in the proximity of the entrance. Recorded data shows that temperature is constant along the tunnel. That is, there is no change with depth of the tunnel below surface, which is up to 433m. It was found that temperature mainly depends upon season and upon outer air that is supplied by ventilation to the tunnel. Highest temperature was recorded during summer (20 to 27 °C), when inner and other temperature are in approximate equilibrium. Lowest inner temperature was recorded during winter (12 to 17 °C), when difference from outer temperature rises. Relative humidity was measured in 14 cases. Recorded data shows random character, so no relations were derived, except that inner air is more humid on average and it's humidity varies much less compared to the outer air. Outer humidity ranges between 36 and 99%. Inner humidity ranges between 53,6 and 99,3 %, and it was 11,8% higher on average. Air pressure was measured in 15 cases. It was found that it corresponds to the outer atmospheric pressure. There is normal pressure drop with distance from tunnel entrance, as vertical alignment of the tunnel changes it's altitude. © The Author(s) 2015.

Sedlar D.K.,Rudarsko geolosko naftni Fakultet Sveucilista U Zagrebu | Hrncevic L.,Rudarsko geolosko naftni Fakultet Sveucilista U Zagrebu | Brkic V.,INA D.d. Zagreb
Rudarsko Geolosko Naftni Zbornik | Year: 2010

Production of unconventional gas plays a double role in the case of liquefied natural, gas (LNG) industry. Technological development of gas production from unconventional resources could result in significant decrease of LNG import demand but at the same time unconventional resources also represent a potential for new sources of LNG supply. In. past few years unconventional gas production in. North America has increased constantly what has contributed to natural gas prices decrease and LNG imports reduction. The rise of unconventional gas production along with, global, recession significantly influenced LNG demand decrease in the USA. Concerning unconventional gas production rapid development, potential, decrease of LNG demand in rest of the world is expected.

Exploration and production, of mineral resources, especially hydrocarbons, are from ecological point of view, one of the most sensitive activities. Concerning global ecological standards, which have also been enforced into petroleum, industry, exploration and production of mineral energy sources have to be based on compliance with introduced environmental and human health protection requirements. Since it is expected that Croatia will join European. Union, in the near future, it is necessary to develop institutional and legislative frameworks for enabling and regulating the harmonization of mineral resources exploration and production waste disposal with European Union directives and regulations. Petroleum, industry waste disposal by injection into suitable geological formations is one of environmentally acceptable methods for petroleum industry waste management.

Ruzicic S.,Rudarsko geolosko naftni fakultet Sveucilista u Zagrebu | Bacic A.,Rudarsko geolosko naftni fakultet Sveucilista u Zagrebu | Bal M.,Rudarsko geolosko naftni fakultet Sveucilista u Zagrebu | Domitrovic M.,Rudarsko geolosko naftni fakultet Sveucilista u Zagrebu | And 7 more authors.
Rudarsko Geolosko Naftni Zbornik | Year: 2014

Samples of red and white wine together with corresponding soils from the domestic vineyards of the continental Croatia were selected for analysis. Vineyard soil cover (Stagnosols and Rendzina) is developed over the Plio-Quaternary non-consolidated deposits (gravel, sand, silt, clay) or marly limestones. Within soils overlying non-consolidated deposits containing clays pH value range from 5.4 to 6.6, whereas maximum measured pH of 7.5 is attributed to soil developed over marly limestones.Soil and wine samples was determined by the total content of copper and iron using flame atomic absorption spectrometry (FAAS). Results are compared to the maximum permitted concentrations (MPC) by the relevant Croatian regulations. Copper concentrations are elevated within all measured wines (from 1.7× to 2.0× with respect to MPC) and two soil samples (up to 2.4× with respect to MPC), due to extensive use of agrochemicals in the vineyards. Increased concentrations of iron within wine and corresponding soil were determined at locality with low soil pH (5.5).Preliminary research demonstrate a plausible link between the content of elements within soils developed over a specific lithology and associated wines. Increased copper concentration within wines of domestic production points to need for education of population in line with use of eco-agrochemicals. Further extensive studies with detailed physico-chemical processing of soil samples are needed. © 2014, University of Zagreb. All rights reserved.

Klanfar M.,Rudarsko geolosko naftni Fakultet Sveucilista U Zagrebu | Vulin D.,Rudarsko geolosko naftni Fakultet Sveucilista U Zagrebu | Veinovic Z.,Rudarsko geolosko naftni Fakultet Sveucilista U Zagrebu
Rudarsko Geolosko Naftni Zbornik | Year: 2010

The potential of coal bed methane has not been evaluated in Croatia so far. For several selected sites in Labin basin data on the composition of coal and the depths and thicknesses of coal layers were collected. Assessment and comparison of the methane content in coal by using the Langmuir isotherm, the general curves of sorption and Kim's method was made and evaluation of the quality of each assessment as well. The analysis resulted with coal bed methane content between 9.5m3/t 11.73m3/t calculated by Kim's equation. By comparing the sorption of pure methane and sorption of CO 2, in order to maintain the pressure in a coal bed and higher recovery of methane, the CO2 could be one of the options for injecting fluid. Geometry of coal layers was not defined and therefore it is not possible to estimate the total content of methane.

Posavec D.,Rudarsko geolosko naftni Fakultet Sveucilista U Zagrebu | Simon K.,Rudarsko geolosko naftni Fakultet Sveucilista U Zagrebu | Malnar M.,Rudarsko geolosko naftni Fakultet Sveucilista U Zagrebu
Rudarsko Geolosko Naftni Zbornik | Year: 2010

Modern liquefied natural gas carriers are double-bottom ships classified according to the type of LNG tank. The tanks are specially designed to store natural gas cooled to -161°C, the boiling point of methane. Since LNG is highly flammable, special care must be taken when designing and operating the ship. The development of LNG carriers has begun in the middle of the twentieth century. LNG carrier storage space has gradually grown to the current maximum of 260000 m3. There are more than 300 LNG carriers currently in operation.

Strgar H.,Rudarsko geolosko naftni fakultet Sveucilista u Zagrebu | Domitrovic D.,Rudarsko geolosko naftni fakultet Sveucilista u Zagrebu | Zelic B.K.,Rudarsko geolosko naftni fakultet Sveucilista u Zagrebu
Rudarsko Geolosko Naftni Zbornik | Year: 2011

Bentonite, which is a mineral component of geosynthetic clay liners, has important physical and chemical properties that ensure very small hydraulic permeability. The main component of bentonite is a clay mineral called sodium montmorillonite whose very low permeability is due to its ability to swell. The deposits of bentonite are spread all over the world, however, only a very small number of those deposits satisfies all the quality and durability demands that must be met if the bentonite is to be used in the sealing barriers. Depending on the location of installation and their purpose, geosynthetic clay liners must meet certain requirements. Their compatibility with the prescribed criterion is confirmed through various laboratory procedures. Amongst them are tests examining the index indicators (free swell index, fluid loss index, and water absorption capacity). This paper presents results regarding the impact of laboratory air temperature and relative humidity of the testing area on the water absorption capacity. This is one of the criteria that bentonite must satisfy during the quality and durability control of the mineral component of geosynthetic clay liner.

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