Mihaela Toderas

• Professor
• Professor at University of Petroșani

A two-year study (June 2022–May 2024) on the reliability and maintainability of technological equipment at the Pătârș basalt quarry identified critical wear issues in metal components impacting operational continuity. The analysis focused on identifying causes of operational interruptions and evaluating solutions to improve equipment performance. R...

The processes of rock excavation and processing involve intense mechanical stresses on cutting, displacing, and transporting tools, inevitably leading to the phenomenon of dry friction wear. The factors influencing the intensity and mechanisms of wear are complex and interdependent, being conditioned by the physical–mechanical properties of the roc...

Technological equipment in quarries that extract and deliver aggregates for different uses operates in a predetermined flow depending on the type of rocks exploited and the dimensional characteristics imposed on the final products. In this context, the interruptions in operation required to replace high-wear parts (such as the teeth of excavators a...

Corrosion is a major problem in the mining industry, significantly affecting the durability and reliability of mining equipment. In order to better evaluate and understand these effects, in the first part of this study, the analysis by the finite element method of the metallic structure of the rotary arm of an ERc 1400-30/7 bucket excavator type, p...

Technological equipment in quarries that extract and deliver aggregates for different uses operates in a predetermined flow depending on the type of rocks exploited and the dimensional characteristics imposed on the final products. In this context, the interruptions in operation required to replace high-wear parts (such as the teeth of excavators a...

Interdisciplinarity encourages students to make connections between different academic disciplines, fostering a deeper understanding of complex real-world problems. By integrating various subjects, students are able to develop critical thinking skills and apply their knowledge in practical ways. This approach not only enhances their learning experi...

The paper analyses the phenomenon of mining machinery fatigue, focusing on the Bucket Wheel Stacker-Reclaimer KsS 5600/3800x40 machine. To evaluate fatigue cycles under variable and non-periodic force conditions specific to this type of machine, Dirlik method and spectral analysis are applied. Dirlik method provides an innovative approach to stress...

The mining method that is still often used in salt deposits is the room-and-pillar mining method, in which the dimensioning of the most requested element in the system is followed. The pillars are the elements subjected to the greatest loads. Knowing the size and distribution mode of the secondary state of stress—deformation—is a necessity that can...

The steels from which the components of mining machinery are constructed must be based primarily on knowledge of their behaviour under environmental conditions and of the excavation technology. Secondly, the structural changes undergone by the materials due to mechanical and thermal processing and the stresses generated by the action of excavation...

In the field of mining, one of the exploitation methods that is still the most used in rock salt, potassium, and magnesium salt deposits is the method with the room and abandoned pillar. The salt mining method with rooms and pillars represents a unique spatial system for which the establishment of an optimal correlation between the parameters of th...

The long-term response and stability of underground mining works are crucial for ensuring the safety of workers, preventing costly accidents, and maintaining efficient operations. This is primarily due to the critical role these structures play in various industries, including mining, construction, and transportation. Understanding the long-term re...

This study presents the stress-strain state in the dam body depending on the type of rockfill that was performed according to the moment of completion of the dam and the first filling with water. Large dams are a very relevant instance for assessing seismic risk. On the one hand, the dams themselves are valuable, with ramifications for the entire e...

The main objective of this study is to analyse and predict the potential risk of rock salt breakage using the Cox proportional hazard model. Analysed according to the theory of continuous mechanics medium rock massif is a natural environment difficult to know, so the forecasts referring to its behaviour are approximate and uncertain. Such an assert...

One of the simplest and most popular open pit mining procedures is drilling-blasting technology. This enables the extraction of a significant amount of rock and valuable mineral material. Open pit mining relies heavily on the action of blasting employing explosive energy, which is also the essential step in the blasting process that yields a matchi...

Tailings dams are special constructions that are part of a complex of works related to the installations for preparing mining masses. These constructions play a role in the mechanical treatment of wastewater and the safe storage of sterile material resulting from ore processing. The closing and greening of tailings dams is achieved taking into acco...

The equipment in underground mines provides a continuous production flow, depending on the way their quality is preserved during their operation. The TR-7A scraper conveyer subassemblies, which function in the Jiu Valley coal basin and are subjected to abrasion wear, showed a high failure frequency (chains, chain elevators, and driving and turning...

In the underground activity domain, most problems related to mining pressure and mining stability need to be solved by taking into account the time behavior of rocks through an approach of the interaction amidst the rock massif, support system, time through the elastic, viscous and plastic models, namely a rheological approach. In order to choose a...

Any underground work requires the knowledge and application of appropriate techniques and technologies in all stages of implementation of such a project. An important problem in the design of underground works is the knowledge of the characteristics and behaviour of the massif in which the work will be carried out. It depends on the choice of the e...

The penetration of some salt deposits of substantial thickness (500-3,000 m) positioned above the structures with petroleum potential in Romania is conditioned by the rendering of oil structures visible in the deep strata (6,000 m). The crossing of these salt deposits by drilling is a key risk issue both during construction (drilling, cementing) an...

Purpose. Drilling-blasting technology is one of the simplest and most often used techniques in open pit mining. This allows the excavation of a large volume of rock and useful mineral substance. The operation of blasting using the energy of explosives plays an important role in open pit exploitation, being also the key element of the blasting proce...

In the case of Roşia Poieni open pit mine the level of +805 m was established as a daily operating limit; the division into benches was based on this level by dividing into horizontal slices with a thickness of 15 m, equal to the height of the bench. Thus, there were 27 benches in the Curmătura area and 23 benches in the Ruginiş area. The general s...

The main sources of methane emission are located in the undermined coal-bearing strata, which is not taken into account by the requirements of regulatory documents when determining the category hazard of coal mines. Gas emission from each undermined source is not equally dependent on the tons of coal mined. The relative gas emission changes during...

The mining sector is a particularly important field that has the ability to support the economic development of a country by supplying various mineral products that are used as raw materials in other sectors of activity. When the depth at which a deposit is located and the geological conditions allow, the exploitation of useful mineral substances i...

Sprayed concrete is a traditional building material, but at the same time it represents a highly innovative technology. The development of sprayed concrete includes material science and advances spraying equipment technology. The performance and characteristics of sprayed concrete depend mainly on the condition of its application, equipments, exper...

A theoretical scheme of gas release from the coalbed under production by treatment workings has been developed. The sizes of zones of different intensity of gas release from the working thickness are set according to the characteristic points of muld shift of the earth's surface. Total amount of releasing gas is determined by the area of the develo...

The main sources of methane emission are located in the undermined coal-bearing strata, which is not taken into account by the requirements of regulatory documents when determining the category hazard of coal mines. Gas emission from each undermined source is not equally dependent on the tons of coal mined. The relative gas emission changes during...

The paper explores the industrial tourism development potential of a former mining area in Petrila, Jiu Valley, Romania, drastically affected by deindustrialization, in order to build a theme park in the old mine site. The research context is determined by the current economic and social state of the area, and also by the potential of the identifie...

Sprayed concrete is a traditional building material, but at the same time it represents a highly innovative technology. The development of sprayed concrete includes material science and advances spraying equipment technology. The performance and characteristics of sprayed concrete depend mainly on the condition of its application, equipments, exper...

The main problem of former industrial areas with history of mining exploitation is the impact of specific activities both on the environment as well as on the social and economic life of the population. In this context, we talk about the Jiu Valley, a mono-industrial area where significant environmental degradation is observed and which did not ben...

Purpose. The analysis of the current underground mine workings, both those that are in operation and works located within the mining perimeters where activity was stopped, is leading directly to the problem of stability, i.e. safety. The aim of the paper is the stability analysis of underground workings located in strongly metamorphosed andesite an...

Abstract The opportunities offered by rock mechanics as a science are not fully and efficiently applied in the design and assessment of underground constructions performed in salt massifs, especially in the efficient design and long-term lifetime of the geometrical elements that characterize the exploitation method with rooms and pillars. It can b...

The rock massif is a natural environment difficult to know; the predictions regarding its behaviour are only approximate, even uncertain. The four fundamental features, namely, rock massifs, are natural, discontinuous, heterogeneous and anisotropic environments have multiple consequences and raise really difficult issues in the mining field and gen...

The main problem of former industrial areas with history of mining exploitation is the impact of specific activities both on the environment as well as on the social and economic life of the population. In this context, we talk about the Jiu Valley, a mono-industrial area where significant environmental degradation is observed and which did not ben...

It is a certainty that a rock massif is a very complex environment, known only partially; in the laboratory we cannot produce all the details encountered in situ; therefore, most of the properties determined experimentally not fully express their real value that they have in rock massif. As theoretical basis we might consider theory of similitude i...

Geomechanical assessment of rocks requires knowledge of phenomena that occur under the influence of internal and external factors at a macroscopic or microscopic scale, when rocks are submitted to different actions. To elucidate the quantitative and qualitative geomechanical behavior of rocks, knowing their geological and physical–mechanical charac...

Purpose. Generation of relative humidity fluctuations lead to a further decrease in the resistance of rocks, which involves the swift evacuation of groundwater from mining works. For andesitic rocks strongly hydrothermal altered it was found an irreversible phenomenon of the effect of humidity upon their strength, while this phenomenon is accompani...

Tailing dams are special hydraulic constructions of retention, of permeable type, and represents all works related to installations of preparing mining masses, on one hand having as a purpose the mechanical treatment of waste water, and on the other hand safe storage generally indefinitely or undetermined, the sterile resulting from ores processing...

The rock massif is a natural environment difficult to know; the predictions regarding its behaviour are only approximate, even uncertain. The four fundamental features, namely, rock massifs, are natural, discontinuous, heterogeneous and anisotropic environments have multiple consequences and raise really difficult issues in the mining field and gen...

The rock massif is a natural environment difficult to know; the predictions regarding its behaviour are only approximate, even uncertain. The four fundamental features, namely, rock massifs, are natural, discontinuous, heterogeneous and anisotropic environments have multiple consequences and raise really difficult issues in the mining field and gen...

Analyzed according to the theory of continuous mechanics, medium rock massif is a natural environment difficult to know, so the forecasts referring to its behaviour are approximate and uncertain. Such an assertion becomes a certitude, even resulting from reality; consequences of the four fundamental features of massif are multiple and involve reall...

Large Dams are a particularly important case of seismic risk assessment. On the one hand, the dams themselves have a high value, having implications for the whole economy, through the production of electricity, water supply systems for irrigation and flood prevention etc. On the other hand, structural damage of a dam can lead to major disasters, th...

The thorough analysis of undesired events occurred in the Jiu Valley collieries, such workplace accidents, occupational diseases, near-misses, coal mine fires, self-heating phenomena, methane and coal dust explosions, safety indexes analysis, the related costs and the loss of production costs should be the ground that underlies the establishment of...

The thorough analysis of undesired events occurred in the Jiu Valley collieries, such workplace accidents, occupational diseases, near-misses, coal mine fires, self-heating phenomena, methane and coal dust explosions, safety indexes analysis, the related costs and the loss of production costs should be the ground that underlies the establishment of...

Analiza evenimentelor nedorite produse la unităţile miniere din Valea Jiului (accidente de muncă, boli profesionale, incidente periculoase, focuri de mină, fenomene de autoîncălzire, decese la locul de muncă), analiza indicilor de securitate, analiza evoluţiei certificatelor medicale, a costurilor cu certificatele medicale şi medicamentele acordate...

The thorough analysis of undesired events occurred in the Jiu Valley collieries, such workplace accidents, occupational diseases, near-misses, coal mine fires, self-heating phenomena, methane and coal dust explosions, safety indexes analysis, the related costs and the loss of production costs should be the ground that underlies the establishment of...

This book includes own studies and results obtained by the author in the field of rocks rheology and its implications in the stability - reliability of underground mining works; it was done out of a desire to open the knowledge horizon of rock mechanics and highlight its role in the underground constructions. Particularly, are presented the results...

The article deals with subsurface location depth as one of the most important technical and mining factors in providing safe stability levels for any underground mine working. With increasing depth, takes place a change of mechanical properties of rocks, their transition into a boundary state, which has a special value and influence in relation to...

Selecting the rock massif - support system interaction model involves establishing the model that corresponds to the studied problem, which requires knowledge of the real deformation behaviour of the massive by assessing all involved geomechanical characteristics, but also all the technical, mining and organizational factors, which determines the p...

Solving the problems of geo-mechanics that contribute to achieving the stability - reliability of mine workings involves the knowledge of the rheological behavior of rocks. We emphasize some of these issues, namely: clearing up the natural stress state; characterizing the deformation behavior of the rock massif; the secondary stress - strain of roc...

Ensuring mine workings stability over their entire operation period largely depends on the chosen support system and on their interaction with the surrounding rock. Looking at how the main horizontal mine workings are supported in Jiu Valley coal basin, we found that they fall into the category fulfilling a reinforcement role. From the data provide...

The case of Rosia Montana Mining Museum underlines the importance of promoting tourism in mining on a national basis, to ensure where possible that new employment opportunities are created in tourism in mining and that municipalities are aware of the possibilities for tourism in mining and that these are integrated into their tourism promotional ac...

The main horizontal mining workings related to the opening schemes of the mines in Valea Jiului are underground constructions of which work duration is in a long period of time, needing more fruitful economical-technical solutions for the assurance of the stability during their whole duration of existence. Considering the time parameter, meaning th...