The Velenje coal mine (VCM) is situated on the largest Slovenian coal deposit and in one of the thickest layers of coal known in the world. The thickness of the coal layer causes problems for the efficiency of extraction, since the majority of mining operations is within the coal layer. The selected longwall coal mining method with specific geometry, increasing depth of excavations, changes in stress state and naturally given geomechanical properties of rocks induce seismic events. Induced seismic events can be caused by caving processes, blasting or bursts of coal or the surrounding rock. For 2.5D visualization, data of excavations, ash content and calorific value of coal samples, hanging wall and footwall occurrence, subsidence of the surface and coal burst source locations were collected. Data and interpolation methods available in software package Surfer^®12 were statistically analyzed and a Kriging (KRG) interpolation method was chosen. As a result 2.5D visualizations of coal bursts source locations with geomechanical properties of coal samples taken at different depth in the coal seam in the VCM were made with data-visualization packages Surfer^®12 and Voxler^®3.

During the construction of tunnels using tunnel-boring machines (TBMs), the wear of disc cutters is an unavoidable process. The timely replacement of worn disc cutters can have a positive effect on construction time and therefore on costs. The wear of disc cutters can be assessed using various measurement methods. The aim of this article is to show different methods of measuring and evaluating the wear of disc cutters and to present their main advantages and disadvantages. In this study, four different wear-measuring methods were used and applied to a worn double disc cutter: a macroscopic visual inspection, profile measurement with a caliper, weighing, and close-range photogrammetry. The results of the measurements showed that the worn disc cutter was subject to normal abrasive wear, with local steel chipping occurring. Based on the close-range photogrammetry measurements, a profile of the worn disc cutter was also created and compared with the original profile. It was found that the best results for the wear assessment of a disc cutter can be achieved by using several measurement methods simultaneously. The integration of different measurement and evaluation methods is therefore recommended for a comprehensive understanding of disc cutter wear.

The complex hydro-geological situation, particularly in terms of groundwater, has been a constant threat to the mining carried out at the Velenje colliery since its inception. Of particular interest to the authors are the difficulties presented to the colliery by the adjacent sand aquifers, as the water pressure within these sands directly impacts mining safety, and the aquifers themselves are most directly affected by dewatering. In order to monitor water levels and estimate dewatering at the Velenje wells, multi-layered modelling using 3D Finite Difference Method (FDM) has already been carried out. However, FDM is not optimal due to its greater dependence on cell size than on water flow. In 2017 in Velenje, a series of wells will be terminated as a result of mining and mining-induced subsidence, leading to dewatering and danger of flooding. As part of a plan to address this by replacing dewatering structures, a series of drive-in filters will be implemented around the entry and exit point tunnels of a longwall face. Because FDM seems to be inadequate for purposes of optimising this process, the Finite Elements Method (FEM) was applied in this case. Based on such an application of FEM, a prediction of the optimisation of drive-in filters was carried out by the authors.

Groundwater and surface water are strongly connected. Therefore, understanding their interactions is important when studying the water balance of a complex aquatic system. This paper aims to present an integrated approach to study such processes, including a better understanding of the hydrological system behavior in the Ljubljansko polje (Slovenia). The study is based on multivariate statistical analyses of data collected over a long period, including the isotopic composition of groundwater, river water, and precipitation. The hydrology in the study domain was also simulated using a comprehensive modelling framework. Since boundary conditions are essential for simulating groundwater flow in a sensitive aquifer, a modelling system of rivers and channels (MIKE 11) and water flow and balance simulation model (WaSiM) were used to model river dynamics and the percolation of local precipitation, respectively. The results were then used as boundary conditions imposed on a transient state groundwater flow model performed in finite element subsurface flow simulation system (FEFLOW 6.2). Both the locations of recharge areas in the study domain and the calculated fluxes between the Sava River and the aquifer are graphically presented. The study revealed that a combination of the MIKE 11-FEFLOW-WaSiM tools offers a good solution for performing parallel simulations of groundwater and surface water dynamics.

This paper addresses a stability evaluation of artificial slopes in a quarry located in Slovenia that was affected by a rockslide in March 2019. In order to ensure the safety of further production, measures were taken to restore the slopes. A stability assessment of the remaining parts of the quarry was conducted. To ensure quality spatial data, an upgraded study based on terrain mapping and aerial photogrammetric imaging using an unmanned aircraft was carried out, in addition to a traditional field survey of the quarry. So that the data were qualitatively useful, a digital terrain and discontinuity model was developed. Projections of the discontinuities occurring in the quarry and in the wider area were determined. The focus of the modeling was finding the main systems of discontinuities and projecting these systems onto the unexcavated parts of the quarry.