Finite Element Modelling of the Stability of Underground Mining Excavations at Old Mines – Slănic Salt Mine (original) (raw)
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Geotechnical and Geological Engineering, 2020
Underground mining continues to progress to difficult, complex and deeper levels in order to tackle ascending demand of minerals. These deep mining occurs in a very hard conditions, in which right practice must be implemented in order to overcome the technical and safety challenges and reap economic gains. The redistributed stresses, large deformations and creeping behavior in such environments worried engineers and geoscientific researchers. The working technic in Boukhadra iron mine is based on the sublevels slaughtered, with room, pillar workings and roof behaviour. Based on rock mechanics and geotechnical engineering methods, our research adopted geo-mechanical and numerical approaches to predict the rock mass behaviour in Boukhadra underground mine and to deal its stability problem. The results show that plastic deformations and stress points increasingly in pillars. In zones with low cover, the tensile zones develop at the roof, leading to a progressive rupture giving rise to a droop. In some areas, fractures develop in a rather remarkable way; in this case the breaking of the pillars and collapse can occur generalized and brutal. The stability of roomand-pillar mines does not depend only pillars. It involves the determination of critical factors and limits of mining. Our study demonstrates that the use of scientific and technical achievements, have become a necessity in mining.
Long Term Analysis of Deformations in Salt Mines: Kłodawa Salt Mine Case Study, Central Poland
Archives of Mining Sciences
Located in central Poland, the Kłodawa salt dome is 26 km long and about 2 km wide. Exploitation of the dome started in 1956, currently rock salt extraction is carried out in 7 mining fields and the 12 mining levels at the depth from 322 to 625 meters below sea level (m.b.s.l.). It is planned to maintain the mining activity till 2052 and extend rock salt extraction to deeper levels. The dome is characterised by complex geological structure resulted from halokinetic and tectonic processes. Projection of the 3D numerical analysis took into account the following factors: mine working distribution within the Kłodawa mine (about 1000 rooms, 350 km of galleries), complex geological structure of the salt dome, complicated structure and geometry of mine workings and distinction in rocks mechanical properties e.g. rock salt and anhydrite. Analysis of past mine workings deformation and prediction of future rock mass behaviour was divided into four stages: building of the 3D model (state of mi...
Sustainability, 2020
The hard coal seams in the Jiu Valley mining basin have been mined with different mining methods and technologies, including with the complete caving of the surrounding rocks and with top coal caving. These mining systems have led to the degradation of the ground surface by producing subsidence of the land, ranging from a few meters up to tens of meters, in the areas with thick coal seams with high dips. When the limits of the main safety pillars are accidentally exceeded whilst mining, buildings situated either below the ground or on the surface are affected. In the future, the possibility exists of mining some of the very large reserves that are immobilized in the main safety pillars, where the gentle dip seams are stored. In consideration of the above, in order to study the behaviour of typical buildings that are under the influence of underground mining and to develop a model of the stress state in the structural elements of the structures, finite element modelling is used. As s...
Numerical study on deformation around underground mining structures (Algeria)
Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu
Purpose. To study the stability of underground mining structures using numerical method based on finite elements, two-dimensional (2D), Finite Element (FE) modeling using GEO5 calculation model. Methodology. To consider the influence of geotechnical parameters, the tunneling is carried out by the NATM method. In order to check settlements in soft ground and to carry out the work in complete safety, we used software based on the finite element method. Findings. Determination of the range and prediction of subsoil displacements are necessary when designing this type of structure due to the need to ensure the safety of the active environment located in the zone of influence. Originality. The originality of this work is the characterization of the soil of the studied region, determining of the different physical and mechanical properties as well as the modeling with a recent calculation model based on the Mohr-Coulomb behavior mode. Practical value. Given the characteristics of the curr...
Case Study: Stability Assessment in Underground Excavations at Vazante Mine - Brazil
Soils and Rocks
Currently, most studies on stability of underground excavations include two separate analyses: the elastoplastic behavior of rock masses and/or kinematic analysis of possible wedges and blocks formed in the excavation walls. This paper presents a case study carried out at the Vazante Zinc Mine in Minas Gerais, Brazil, where studies on stability of underground excavations in discontinuous media included survey reports, laboratory tests and in-situ collected data. In this context, where galleries and mining stopes are excavated in discontinuous media, collapse events caused by the presence of discontinuities are common. First, the spatial orientation, geometric arrangement and mechanical characteristics of the discontinuities intercepted by the core samples were collected. The spatial orientation was based on guide layers, which are discontinuities with known dip direction and variable and dip. The geotechnical characteristics of the discontinuities were obtained by correlation with the roughness degree and the nature and weathering degree of the filling material. From there, the geological-geotechnical models were developed, which were the basis for the finite element analysis in discontinuous media of the designed excavations in the sections 13225 and 13300, between levels 210 and 345 of the mine. For comparison and complementation, wedge kinematic analysis and finite element analysis in equivalent continuous media were performed and, later, an arrangement for the reinforcement system was suggested. The results of these studies show that, in general, continuous models tend to be more conservative and have wider deformation zones, while discontinuous models are able to show in more detail where the displacements occur, and how the families of discontinuities affect the stability of excavations.
Safety excavation in salt rock used for underground storage in Romania
The 25th International Symposium on Automation and Robotics in Construction. ISARC-2008, 2008
The use of underground excavation in salt-rock formations for waste storage imposes the precise analysis of properties of salt rock and a stress analysis. One of the main mechanisms responsible for a degradation of isolation ability of the rock salt is the generation and development of cracks under influence of mining processes. Various aspects of cracking in salt rocks are studied-both in situ and in laboratory tests-for rocks of the Targu Ocna Salt Mine. The aim of this paper is to describe the time behavior of rock-salt around underground mining excavations and in situ stress monitoring system of rock mass was proposed.
Stability Analysis of Underground Mining and their Application on the Mine Chaabte El Hamra, Algeria
Elsevier Procedia Earth and Planetary Science, 2015
Method room and pillar sizes are key factors for safe mining and their recovery in open-stop mining. This method is advantageous due to its simplicity and requirement of little information to be used. It is probably the most representative method among the total load approach methods although it also remains a safe design method. Using a finite element software (PLAXIS 3D), analyses were carried out with an elasto-plastic model and comparisons were made with methods based on the total load approach. The results were presented as the optimization for improving the ore recovery rate while maintaining a safe working environment.
Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, 2019
Purpose. Analysis of the current and proposed room and pillar exploitation technique of the Zinc mine (Chaabet ElHamra) by two different approaches, the tributary area (TAM) for analytical method and numerical method (Fi nite Element Method FEM) through PLAXIS 3D software. methodology. In this work, the stability analysis of the roomandpillar of the Chaabet ElHamra mine was per formed. Firstly, the safety factor for both conditions was calculated by TAM: 1) the current operation using 8.0 m wide rooms with 4.0 × 4.0 m pillar sections; 2) the proposed technique using 9.0 m wide rooms with 3.0 × 3.0 m pillar sections. Secondly, the numerical method was used to analyze pillar stability and total displacement of the proposed technique through the PLAXIS 3D software. findings. Using more than one method in underground mining for analysis of the existing or proposed technique is the best solutions for achieving reliable results. originality. The originality of this work is to use two diff...
Determining Mechanical Properties and Material Models of Subsoil for Buildings in Mining Areas
AGH Journal of Mining and Geoengineering, 2012
Preventing mining damage buildings can sustain, entails above all determining correctly interactions in the soil (and consequently the load-bearing structure) caused by exploitation. Processes involved in deposit mining cause damage to a rock mass’s structure around the excavation and cause deformation of surface layers. Under Polish conditions, underground mines are located almost exclusively in areas, where exploration has taken place for many years. Mining history of the Upper Silesian Coal Basin region dates back as far as 160 years. It comes as no surprise, than that rock mass’s structure in those areas has been signio cantly affected. Repeatable mining in? uences leave their mark on mechanical properties of soil. Therefore it is important, not only to factor in at the stage of designing a building the direct impact of planned excavation, but also properties of soil have to correctly evaluated. Investigation of geologic and geotechnical conditions of foundations should draw bas...
Finite-element modeling of the behavior of underground caverns excavated in rock salt
Numerical Methods in Geotechnical Engineering, 2014
Underground caverns are recognized as the appropriate places to store compressed air, natural gas, CO 2 and H 2 . Rock salt is one of the prime alternatives for the construction of these underground cavities because of its favorable properties. Low permeability, adequate mechanical properties and solubility in water are some of the unique features that make the rock salt distinct from other rock materials. On the other hand, design and stability analysis of an underground cavern require a specific constitutive law which can describe the material behavior of the rock salt under different geological conditions at different time scales. This paper presents the numerical modeling of the time-dependent behavior of underground caverns excavated in rock salt. An elasto-viscoplastic constitutive law is used to describe the transient and stationary creep of the rock salt around the cavern. To achieve this goal, this constitutive model is implemented into the finite element code Code-Bright.The efficiency and the applicability of this model is investigated in comparison with another existing creep model which is available in Code-Bright program. In the numerical section, the short-term behavior and long-time stability of a typical salt cavern are estimated considering the real operating condition of salt repositories. Finally, the time-dependent response of the salt cavern is evaluated and some general recommendations for the use of the presented constitutive model in the practice will be given.