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Experience in design and construction of the Log tunnel

Abstract

A twin highway Log tunnel is a part of a new motorway connection between Maribor and Zagreb, section Draženci-Gruškovje, which is located towards the border crossing between Slovenia and Croatia. The tunnel is currently under construction, and only the excavation works have been completed during the writing of this paper. The terrain in the area of the Log tunnel is diverse, and the route of the highway in its vicinity is characterised by deep excavations, bridges or viaducts. The Log tunnel is approximately 250 m long, partly constructed as a gallery. The geological conditions are dominated by Miocene base rock, featuring layers of well-connected clastic rocks, which are covered by diluvium clays, silts, sands and gravels of different thicknesses. Due to the short length of the tunnel, the usual separation of the motorway route to the left and the right tunnel axes was not carried out. Thus, the tunnel was constructed with an intermediate pillar and was designed as a three-lane tunnel, including the stopping lane. The construction of the tunnel was carried out using the New Austrian tunnelling method (NATM), in which the central adit was excavated first and the intermediate pillar was constructed within it. The excavation of the main tubes followed and was divided into the top heading, bench and the invert, enabling the intermediate pillar to take the load off the top heading of both tubes. The secondary lining of the tunnel is currently under construction. The experience of the tunnel construction gathered so far is presented in the paper. The main emphasis is on the construction of the intermediate pillar, which had to take the significant and asymmetrical ground load.

Open access
Geodynamic condition of formation of favorable structural positions for ore-grade gold placement in auminzatau-beltau ore area (the central kyzyl kum, western uzbekistan)

Abstract

Work is directed on studying of a geodynamic condition under which the structural positions controlling process of endogenous ore formation were formed. It is shown that explosive region tectonics under the influence of regional tectonic efforts formed structural elements (positions) which controlled formation of gold deposits. It is recognized that structural positions are defined by variety of systems of disjunctive dislocation and their relationship among themselves. Formation of favorable positions depends as well on morphology of ore controlling structures, on degree of their tectonic activity and spatial situation in relation to the direction of tectonic (geodynamic) efforts.

Open access
Testing of thermal fatigue resistance of tools and rolls for hot working

Abstract

In the present contribution two tests for thermal fatigue testing, which have been developed in our group, are presented. First test has provided internal cooling system of sample, while second has external cooling. For both tests heating and cooling of samples are computer guided that enables very reliable results of testing. The first test is more appropriate for testing the base material, i.e. roll cast irons, roll steels, tool steels. The second test is more appropriate for experiments that are aimed for selection of appropriate tool surface treatment, i.e. laser cladding, nitriding, coating, etc., and to compare and to achieve improved resistance against thermal fatigue of produced surface layers.

Open access
Using artificial neural network to predict dry density of soil from thermal conductivity

Abstract

Artificial neural network (ANN) was used to predict the dry density of soil from its thermal conductivity. The study area is a farmland located in Abeokuta, Ogun State, Southwestern Nigeria. Thirty points were sampled in a grid pattern, and the thermal conductivities were measured using KD-2 Pro thermal analyser. Samples were collected from 20 sample points to determine the dry density in the laboratory. MATLAB was used to perform the ANN analysis in order to predict the dry density of soil. The ANN was able to predict dry density with a root-mean-square error (RMSE) of 0.50 and a correlation coefficient (R2) of 0.80. The validation of our model between the actual and predicted dry densities shows R2 to be 0.99. This fit shows that the model can be applied to predict the dry density of soil in study areas where the thermal conductivities are known.

Open access
The adequacy of the facility and the location of waste collection

Abstract

The purpose of this article is to summarise some provisions of the legislation applicable in the territory of the Republic of Slovenia that have to be complied with when selecting facilities intended for waste collection. In addition to equipment, the adequacy of such facility also depends on its site. Not only waste management legislation and environment protection legislation, but also legislation governing water, nature preservation and conservation, natural and cultural heritage and mining legislation stipulate the possibility of using facilities where collectors can sort and store waste before depositing it for subsequent management. This paper presents location examples where various factors exclude the possibility of using facilities as waste collection centres.

Open access
Application of terrestrial laser scanning in documenting an underground coal mine pumping station

Abstract

Recently, a new underground pumping station was constructed 41.5 m below sea level and equipped, which has now become the main underground pumping station of the Velenje Coal Mine (VCM). In this study, use of terrestrial laser scanning (TLS) to acquire the 3D data of the engine room of the underground pumping station is presented. TLS is an advanced technique in spatial information data acquisition, which allows the equipment in the underground pumping station to be digitally captured with unprecedented resolution and accuracy. Integration with metric imagery allows 3D photorealistic models to be created for interpretation and visualisation. The final result shows the actual 3D image of the object recorded with a relative accuracy of a few millimetres. TLS is ideal for capturing the original state before construction commences and the final state after its completion, as well as for both observation of surface changes and detection of deformations. When we have an accurate 3D model of each component in the engine room of the underground pumping station, any maintenance, future upgrades, or modifications can be made with reference to the original state.

Open access
Measurement of company effectiveness using analytic network process method

Abstract

The sustainable development of an organisation is monitored through the organisation’s performance, which beforehand incorporates all stakeholders’ requirements in its strategy. The strategic management concept enables organisations to monitor and evaluate their effectiveness along with efficiency by monitoring of the implementation of set strategic goals. In the process of monitoring and measuring effectiveness, an organisation can use multiple-criteria decision-making methods as help. This study uses the method of analytic network process (ANP) to define the weight factors of the mutual influences of all the important elements of an organisation’s strategy. The calculation of an organisation’s effectiveness is based on the weight factors and the degree of fulfilment of the goal values of the strategic map measures. New business conditions influence the changes in the importance of certain elements of an organisation’s business in relation to competitive advantage on the market, and on the market, increasing emphasis is given to non-material resources in the process of selection of the organisation’s most important measures.

Open access
Physico-chemical trends in the sediments of Agbede Wetlands, Nigeria

Abstract

This study assessed the physico-chemical status of sediments in the Agbede Wetlands with the aim to create a reference archive for the Edo North catchment and to further identify the characteristics mostly influenced by the natural and anthropogenic activities going on at the watershed. Nutrients, zinc, nickel and lead were identified to be mostly of anthropogenic origin, while alkali metals and alkaline earth metals were from both anthropogenic and natural sources. The clustering of stations 1 and 4 indicates that the sediment quality in the lentic systems was not completely excluded from the lotic system, suggesting that principal component analysis (PCA) and cluster analysis (CA) techniques are invaluable tools for identifying factors influencing the sediment quality. The mean values of the particle size distribution were in the following order across the ecosystems: sand (61.86–80.53%) > silt (9.75–30.34%) > clay (7.83–13.89%). The contamination of the water bodies was primarily derived from agricultural run-offs and through geochemical weathering of the top soils. Therefore, our analysis indicates that the concentrations of cations, anions and nutrients in the sediments of the lotic and lentic ecosystems in Agbede Wetlands are not at an alarming level.

Open access
Reliability of system for precise cold forging

Abstract

The influence of scatter of principal input parameters of the forging system on the dimensional accuracy of product and on the tool life for closed-die forging process is presented in this paper. Scatter of the essential input parameters for the closed-die upsetting process was adjusted to the maximal values that enabled the reliable production of a dimensionally accurate product at optimal tool life. An operating window was created in which exists the maximal scatter of principal input parameters for the closed-die upsetting process that still ensures the desired dimensional accuracy of the product and the optimal tool life. Application of the adjustment of the process input parameters is shown on the example of making an inner race of homokinetic joint from mass production. High productivity in manufacture of elements by cold massive extrusion is often achieved by multiple forming operations that are performed simultaneously on the same press. By redesigning the time sequences of forming operations at multistage forming process of starter barrel during the working stroke the course of the resultant force is optimized.

Open access
Geochemistry of Fluvial Sediments from Geregu, Southwest Nigeria

Abstract

Geochemical analysis of fluvial sediments on the banks of River Ero using inductively coupled plasma mass spectrometry illustrates their maturity, provenance and tectonic setting. The analysed sediment samples show low SiO2/Al2O3 ratios of 2.92-2.99 (units FL_A, FL_B and FL_E) and high SiO2/Al2O3 ratios of 4.064-4.852 (units FL_C, FL_D, FL_F and FL_G). Sediments were geochemically classified as shales (units FL_A, FL_B and FL_E) and greywackes (units FL_C, FL_D, FL_F and FL_G). Variability in sediment maturity (FL_F > FL_G >FL_C >FL_D >FL_A > FL_B > FL_E) parallels a decreasing order in the ratios of SiO2/Al2O3 and K2O/Al2O3, as well as the proportion of quartz grains and matrix components. Evidence from Al2O3/TiO2, K2O, Rb, La/Co, Th/Co, Cr/ Th, Th/Cr, La/Th-Hf, Th-Hf-Co and rare earth element contents of sediment samples suggest felsic protoliths of upper continental crust in a passive margin tectonic setting. An insignificant contribution of mafic components from the source is, however, inferred based on the Ni and Cr contents of the sediment samples. Combined Eu anomalies <0.85 and (Gd/Yb)n ratios <2.0 (1.53- 1.82, average 1.65) suggest post-Archean protoliths.

Open access