Mining Layouts Research Articles

Dynamic mechanical characteristics of coal in front of the mining face under different mining layouts

To study the dynamic mechanical characteristics of coal in the area affected by mining in front of the mining face under different mining methods, an improved split Hopkinson pressure bar (SHPB) was used to apply different static loads to different positions. Then, dynamic mechanical tests were conducted on coal at different positions on the mining face, analyzing the dynamic response under strong dynamic load disturbances, under three different mining layouts. Within the range of static water pressure to the peak support pressure, the dynamic strength of coal gradually increases with increasing distance from the mining face. The dynamic strength is the smallest at the peak support pressure stress, and under strong external disturbances, instability and failure are increasingly likely to occur at the peak stress. Under the same loading rate conditions, the dynamic strength of the peak stress in coal is as follows: Protective coal-seam mining (PCM) > Top-coal caving mining (TCM) > Nonpillar mining (NM).

Using legacy 3D seismic data and source parameters of mining‐induced earthquakes to mitigate the risk of rockbursting in Kloof Gold Mine, South Africa

AbstractRockbursts pose a significant risk in deep gold mines in the Witwatersrand Basin of South Africa as they may damage the excavation, injure workers, and delay production. We analysed the source mechanisms of 75 large mining‐related seismic events (ML 1.5–2.7) that caused damage to stopes in Kloof Gold Mine and used legacy 3D reflection seismic data to delineate the ore body and geological structures that may be correlated with mining‐related seismic events. The 75 seismic events took place at depths of 1600–4200 m below surface. Most events were located close to stopes mining the Ventersdorp Contact Reef ore body. The S‐to‐P‐wave energy ratio (Es/Ep) from the analysed seismic events ranged from 1.1 to 19.9. The source mechanisms of mining‐induced seismic events aid in understanding the dominant modes of failure. Planes of weakness may be the result of mining‐induced stresses or pre‐existing geological structures such as faults and dykes. The Es/Ep ratio, focal mechanism and moment tensor solutions were correlated to the underground mapped and seismically defined geological structures. Approximately 44% of the events showed strong correlation with the known underground mapped and seismically imaged geological structures (faults and dykes), whereas 56% of the events were related to elements of the mining geometry (dip pillars, abutments and remnants). This information enables mining layouts to be modified to minimize the risk of rockbursting.

Coal permeability evolution during damage process under different mining layouts

ABSTRACT Coal permeability is akey component that affects gas migration. Considering seepage behavior of gas during mining is critical for improving the production profile of coal-bed methane (CBM) wells, and preventing coal and gas outburst. Aseries of seepage tests have been carried out to simulate the coal permeability evolution law during mining-induced actions. Coal damage has been assessed by using atri-axial servo seepage testing system. The results show that the coal permeability under PCM, Top-coal Caving Mining (TCM) and NM are all kept constant before the deviatoric stress reaches the peak strength, then increases mildly and finally increases rapidly. The effective stress decreases during confining pressure relief, and the permeability increases exponentially with the decrease of effective stress, which is quite different from the traditional triaxial compression test. According to continuum damage mechanics, adamage constitutive model of coal was proposed to characterize coal mechanical characteristics by mining-induced activities. Furthermore, according to the matchstick model, anew coal permeability model is proposed, which could accurately reflect seepage behavior under different mining layouts.

Fault-Induced Coal Burst Mechanism under Mining-Induced Static and Dynamic Stresses

Fault is a common geological structure that has been revealed in the process of underground coal excavation and mining. The nature of its discontinuous structure controls the deformation, damage, and mechanics of the coal or rock mass. The interaction between this discontinuous structure and mining activities is a key factor that dominates fault reactivation and the coal burst it can induce. This paper first summarizes investigations into the relationships between coal mining layouts and fault occurrences, along with relevant conceptual models for fault reactivation. Subsequently, it proposes mechanisms of fault reactivation and its induced coal burst based on the superposition of static and dynamic stresses, which include two kinds of fault reactivations from: mining-induced quasi-static stress (FRMSS)-dominated and seismic-based dynamic stress (FRSDS)-dominated. These two kinds of fault reactivations are then validated by the results of experimental investigations, numerical modeling, and in situ microseismic monitoring. On this basis, monitoring methods and prevention strategies for fault-induced coal burst are discussed and recommended. The results show that fault-induced coal burst is triggered by the superposition of high static stress in the fault pillar and dynamic stress from fault reactivation. High static stress comes from the interaction of the fault and the roof structure, and dynamic stress can be ascribed to FRMSS and FRSDS. The results in this paper could be of great significance in guiding the monitoring and prevention of fault-induced coal bursts.

Acoustic Emission Characteristics of Coal Samples under Different Stress Paths Corresponding to Different Mining Layouts

Research on the mining-induced mechanical behavior and microcrack evolution of deep-mined coal has become increasingly important with the sharp increase in mining depth. For rock units in front of the working face, the microcrack evolution characteristics, structural characteristics, and stress state correspond well to mining layouts and depths under deep mining. The acoustic emission (AE) characteristics of typical coal under deep mining were obtained by conducting laboratory experiments to simulate mining-induced behavior and utilizing AE techniques to capture the variation in AE temporal and spatial parameters in real time, which provide an important basis for studying the rupture mechanisms and mechanical behavior of deep-mined coal. The findings were as follows: (1) AE activity under deep mining was characterized by three stages, corresponding to crack initiation, crack stable propagation, and crack unstable propagation. As the three stages proceeded, the AE counting rate and AE energy rate presented stronger clustering characteristics, and the cumulative AE counting and cumulative AE energy exhibited a sharp increase by an order of magnitude. (2) The crack initiation and the main stages of crack propagation were determined by characteristic points of variation curves in the AE parameters over time. In the main crack propagation stage, the number of cumulative AE events and the cumulative AE counts were similar among the three mining conditions, while coal samples under coal pillar mining released the largest amount of AE energy. The amount of accumulated AE energy released by coal samples increased by one order of magnitude according to the sequence of protective coal-seam mining, top-coal caving mining, and nonpillar mining. (3) Fractal technology was applied to quantitatively analyze the AE spatial evolution process, showing that the fractal dimension of the AE location decreased as the peak stress increased, corresponding to protective seam mining, caving-coal mining, and nonpillar mining. The above results showed that the deformation and fracture characteristics of coal under deep mining followed a general law, but were affected by different mining conditions. The crack initiation and main rupture activity of coal occurred earlier under the conditions of protective seam mining, top-coal caving mining, and nonpillar mining, successively. Moreover, nonpillar mining induced the strongest and highest degree of unstable rupture of the coal body in front of the working face.

Size and spatial fractal distributions of coal fracture networks under different mining-induced stress conditions

Coal permeability is a key issue in CO2 injection and enhanced coalbed methane (CBM) recovery, and it is determined by the fracture network, which is strongly influenced by mining-induced stress evolutions. For a comprehensive understanding of the size and spatial distribution characteristics of coal fracture networks under different mining-induced stress conditions, a series of laboratory experiments, computed tomography (CT) scans and image analyses focusing on 3D coal fracture systems have been conducted considering the stress conditions induced by three typical mining layouts, i.e., top-coal caving mining (TCM), non-pillar mining (NM) and protective coal-seam mining (PCM). The size and spatial distributions of mining-induced coal microfractures and the anisotropic tortuosity characteristics of coal fracture networks have been quantitatively determined based on fractal theory. The results show that the size distributions of microfracture geometries, the fractal dimensions of fracture size distribution and the tortuosity of the mining-induced coal fracture networks vary according to the mining-induced stress conditions, resulting in differences in the seepage capacity of coal masses. The coal samples subjected to PCM conditions have the highest percentage of large microfractures, and those exposed to NM conditions have the lowest percentage. The fractal dimensions (Da and Dd) of the microfracture size distributions of the typical coal specimens decrease in the order of PCM, NM and TCM conditions, and the Da and Dd of coal specimens without pre-mining unloading-expansion simulation (PUES) are much lower than those of specimens with PUES. The tortuosity fractal dimensions (δ) of the mining-induced fracture network are spatially anisotropic. The ranges of δ for the coal masses exposed to PCM, NM and TCM conditions are 1.0–1.2, 1.2–1.3 and 1.25–1.4, respectively. Using fractal theory and the measured fracture network data, the anisotropic spatial distribution of coal permeability can be theoretically estimated.

Numerical simulation of spatial distributions of mining-induced stress and fracture fields for three coal mining layouts

In this study, the spatial distributions of stress and fracture fields for three typical underground coal mining layouts, i.e. non-pillar mining (NM), top-coal caving mining (TCM) and protective coal-seam mining (PCM), are modeled using discrete element software UDEC. The numerical results show that different mining layouts can lead to different mining-induced stress fields, resulting in diverse fracture fields. For the PCM, the mining influenced area in front of the mining faces is the largest, and the stress concentration factor in front of the mining faces is the lowest. The spatial shapes of the mining-induced fracture fields under NM, TCM and PCM differ, and they are characterized by trapezoidal, triangular and tower shapes, respectively. The fractal dimensions of mining-induced fractures of the three mining layouts decrease in the order of PCM, TCM and NM. It is also shown that the PCM can result in a better gas control effect in coal mines with high outburst potential. The numerical results are expected to provide a basis for understanding of mining-induced gas seepage fields and provide a reference for high-efficiency coal mining.

Numerical studies of improved methane drainage technologies by stimulating coal seams in multi-seam mining layouts

This paper presents procedures and results of the numerical modelling of different stimulation methods as applied to the specific conditions of a multi-seam mining layout at the Zofiówka Coal Mine operated by Jastrzębska Spółka Węglowa (JSW), Poland. Studies reported in this paper include constructions of three types of numerical models: (1) a geological model of the Zofiówka coal mine area based on large set of available data (structure maps, cross-sections, well logs, lithological profiles, laboratory measurements); (2) both large and small scale geomechanical models including the multi-seam mining layout and details of local geomechanical conditions resulting from the application of different stimulation technologies; (3) dynamic flow models including transport properties modified by the geomechanical state of the analysed seam and its surroundings. Resulting drainage process simulations were performed for three different technologies (hydraulic fracturing, high pressure jet slotting, and the use of explosives). Detailed analyses of the technologies pointed out the hydrofracturing and jet slotting as the stimulating methods that can potentially enhance methane drainage from the analysed seam. Quantitative results of the simulations estimate the dependence of the drainage process characteristics upon the basic technological parameters of the stimulation methods.

Coal pillar design when considered a reinforcement problem rather than a suspension problem

Current coal pillar design is the epitome of suspension design. A defined weight of unstable overburden material is estimated, and the dimensions of the pillars left behind are based on holding up that material to a prescribed factor of safety. In principle, this is no different to early roadway roof support design. However, for the most part, roadway roof stabilisation has progressed to reinforcement, whereby the roof strata is assisted in supporting itself. This is now the mainstay of efficient and effective underground coal production. Suspension and reinforcement are fundamentally different in roadway roof stabilisation and lead to substantially different requirements in terms of support hardware characteristics and their application. In suspension, the primary focus is the total load-bearing capacity of the installed support and ensuring that it is securely anchored outside of the unstable roof mass. In contrast, reinforcement recognises that roof de-stabilisation is a gradational process with ever-increasing roof displacement magnitude leading to ever-reducing stability. Key roof support characteristics relate to such issues as system stiffness, the location and pattern of support elements and mobilising a defined thickness of the immediate roof to create (or build) a stabilising strata beam. The objective is to ensure that horizontal stress is maintained at a level that prevents mass roof collapse. This paper presents a prototype coal pillar and overburden system representation where reinforcement, rather than suspension, of the overburden is the stabilising mechanism via the action of in situ horizontal stresses. Established roadway roof reinforcement principles can potentially be applied to coal pillar design under this representation. The merit of this is evaluated according to failed pillar cases as found in a series of published databases. Based on the findings, a series of coal pillar system design considerations for bord and pillar type mine workings are provided. This potentially allows a more flexible approach to coal pillar sizing within workable mining layouts, as compared to common industry practice of a single design factor of safety (FoS) under defined overburden dead-loading to the exclusion of other relevant overburden stabilising influences.

An anisotropic coal permeability model that considers mining-induced stress evolution, microfracture propagation and gas sorption-desorption effects

Anisotropic coal permeability plays an important role in the simultaneous extraction of coal and gas from deep underground. In this study, first, the representative elementary volume of a coal mass is determined based on the natural microfracture distribution in coal. Then, an anisotropic coal permeability model that considers the complex stress evolution process, microfracture propagation and gas sorption-desorption effects was established to comprehensively study the coupled process of the actual mining-induced anisotropic mechanical behaviors and the gas seepage phenomena in the coal. The main characteristic of this model is coupled the stress-fracture-seepage analyses on the mechanical behavior of coal in terms of complex stress evolution. The presented model is verified using two different experimental observations, and a precise mathematical expression of the stress evolution processes induced by different mining layouts is presented to perform the coupled analyses using the presented model. The simulation results exhibit good agreement with the experimental data and reflect the overall trends of the test results fairly well, and the simulation results can appropriately represent the actual mining-influenced coal mechanical behavior. Thus, the model is highly adaptable for simulating various stress boundary conditions and engineering disturbance processes and is applicable for conducting numerical studies on coal fracture propagation, gas sorption-desorption effects and complex mining-induced mechanical behavior. Therefore, this model provides a theoretical basis for further analyses.

A Framework for Geotechnical Hazard Analysis in Highwall Mining Entries

Highwall mining involves driving a series of parallel entries with web pillars in between. These entries are driven by using a continuous miner with attached conveying system to extract locked up coal behind the highwall slope when the open cut coal mine reaches its ultimate limit. These entries are driven unmanned, unventilated and unsupported. Therefore, a detailed knowledge of structural features ahead of operations is essential in assessing the stability of these entries. Highwall mining operations can greatly benefit from accurate structural mapping of rock mass defects. The stability of these entries can be suitably assessed for any major roof failure by adopting discrete fracture network based structural modelling to characterize and delineate the regions of possible major roof failures to prevent damage to the conveyor and burial of the expensive continuous miner. In this paper, a generalized framework is described based on photogrammetric survey, digital mapping and discrete fracture network based structural modelling to characterise such failures for an Indian highwall mining operation. A sensitivity analysis is undertaken to demonstrate the significance of structure persistence in the geotechnical assessment. Such analysis would provide more insight into designing highwall mining layouts and in predicting possible impending highwall failures, and indirectly facilitates reducing machine downtime for better management of highwall mining operations.

Mining-Induced Coal Permeability Change Under Different Mining Layouts

To comprehensively understand the mining-induced coal permeability change, a series of laboratory unloading experiments are conducted based on a simplifying assumption of the actual mining-induced stress evolution processes of three typical longwall mining layouts in China, i.e., non-pillar mining (NM), top-coal caving mining (TCM) and protective coal-seam mining (PCM). A theoretical expression of the mining-induced permeability change ratio (MPCR) is derived and validated by laboratory experiments and in situ observations. The mining-induced coal permeability variation under the three typical mining layouts is quantitatively analyzed using the MPCR based on the test results. The experimental results show that the mining-induced stress evolution processes of different mining layouts do have an influence on the mechanical behavior and evolution of MPCR of coal. The coal mass in the PCM simulation has the lowest stress concentration but the highest peak MPCR (approximately 4000 %), whereas the opposite trends are observed for the coal mass under NM. The results of the coal mass under TCM fall between those for PCM and NM. The evolution of the MPCR of coal under different layouts can be divided into three sections, i.e., stable increasing section, accelerated increasing section and reducing section, but the evolution processes are slightly different for the different mining layouts. A coal bed gas intensive extraction region is recommended based on the MPCR distribution of coal seams obtained by simplifying assumptions and the laboratory testing results. The presented results are also compared with existing conventional triaxial compression test results to fully comprehend the effect of actual mining-induced stress evolution on coal property tests.

Numerical Study of Mine Site Specific Multiseam Mining and Its Impact on Surface Subsidence and Chain Pillar Stress

This paper investigates various multiseam mining related parameters using mine site specific data and numerical simulations. Two important mining effects—subsidence and stress—are analysed for different possible mining layouts. A geological mine dataset has been used to generate a numerical model. The predicted surface subsidence magnitude and surface profile have been compared under different scenarios to assess potential options in multiseam mining strategies. The effects that seam separation distances, mining offset, panel layout and panel orientation each have on surface subsidence and chain pillar stress magnitude have been investigated. The numerical simulation shows that ascending or descending mining directions have little impact on controlling the surface subsidence in multiseam mining and predicted an almost identical maximum stress development at the chain pillars. Numerical simulations infer that the orientation of the top panels control the subsidence profile.

Fractal and volume characteristics of 3D mining-induced fractures under typical mining layouts

Mining-induced fractures, which can release natural gas and enhance gas migration, are indispensable in the co-extraction of coal and methane (CECM). Investigations into mining-induced fracture systems ahead of the coalface are beneficial in elucidating the complex differences between mining processes and their related static and dynamic strata stress fields. Triaxial tests were conducted on coal samples to simulate the mining-induced mechanical behaviors of the coal seam under three widely used mining processes, i.e., top-coal caving mining (TCCM), non-pillar mining (NPM) and protected coal seam mining (PCSM). Mining-induced fractures were created at the laboratory scale. An industrial computed tomography scanning system was employed to scan the ruptured coal samples and measure the geometric characteristics of the fractures associated with each simulated process. Coronal and sagittal views as well as a precise 3D solid geometrical model were reconstructed for each process. It is shown that the mining layout influences the spatial morphology of mining-induced fractures. Using the box-counting method, a quantitative fractal characterization of the fracture system was estimated for each mining method. The estimated average fractal dimensions of the fracture systems generated in the simulated TCCM, NPM, and PCSM processes were 2.0557, 2.0362 and 2.0129, respectively. Additionally, a scale-independent fracture intensity, FI, was defined to further characterize the volume features of the mining-induced fracture systems. The fracture intensity was 0.6 for the NPM process, 0.5 for TCCM and 0.21 for PCSM.

Rock engineering aspects of a modified mining sequence in a dip pillar layout at a deep gold mine

Synopsis Scattered mining was practised on Kusasalethu Mine (previously Elandsrand Gold Mine) prior to 1998, but at deeper mining levels it was no longer feasible, since it would have resulted in unacceptably high stress levels and energy release rates. Longwall mining was not adopted at these depths as the mine required a more flexible mining method owing to the highly variable grade and the presence of geological structures. A mining method was developed that consisted of dip stabilizing pillars for regional support, as well as bracket pillars to clamp geological structures. A strict sequence of extraction was followed and this, together with the particular layout, was called the ‘sequential grid mining method’. This method addressed two key problems, namely negotiating adverse geology and the erratic grade of the Ventersdorp Contact Reef (VCR) orebody. However, a significant drop in production rates resulted in the need for alternatives and improvements to the original mine design. Modifications to the design were proposed in order to increase production rates, and an investigation to consider the rock engineering implications of these modifications was conducted. The study indicated that the modified method, called the ‘multi-raise mining method’, appears to be feasible and might address some of the production problems that were experienced with the original sequential grid design. An analysis of actual seismic data showed no significant differences between the original sequential grid mining and the implemented multi-raise mining. The numerical modelling of the mining layouts showed slightly higher interim energy release rates (ERRs) and average pillar stress (APS) levels during the extraction process. The final values are nevertheless identical to that of the original sequence. The study also investigated the use of a modelled moment method to analyse future seismic trends. The study illustrated that the expected seismic trends will be very similar for the multi-raise method compared to the original sequential grid mining method. This study is nevertheless considered of a preliminary nature and ongoing monitoring and analysis of seismic data at the mine is required to verify the response of the rock mass to the modified sequence and increased extraction rate. In particular, future work needs to investigate the effect of mining rate (advance rates in individual panels as well as volume of mining in particular raise lines) on the level of seismicity.

3D reconstruction method and connectivity rules of fracture networks generated under different mining layouts

In current research, a series of triaxial tests, which were employed to simulate three typical mining layouts (i.e., top-coal caving, non-pillar mining and protected coal seam mining), were conducted on coal by using MTS815 Flex Test GT rock mechanics test system, and the fracture networks in the broken coal samples were qualitatively and quantitatively investigated by employing CT scanning and 3D reconstruction techniques. This work aimed at providing a detail description on the micro-structure and fracture-connectivity characteristics of rupture coal samples under different mining layouts. The results show that: (i) for protected coal seam mining layout, the coal specimens failure is in a compression-shear manner and oppositely, (ii) the tension–shear failure phenomenon is observed for top-coal caving and non-pillar mining layouts. By investigating the connectivity features of the generated fractures in the direction of σ1 under different mining layouts, it is found that the connectivity level of the fractures of the samples corresponding to non-pillar mining layout was the highest.

Influence of different mining layouts on the mechanical properties of coal

Non-pillar mining, top-coal caving and protected coal seam mining are the most popular mining methods in coal exploitation, and the different mining layouts will change the stress state and failure mechanism of coal in front of the working face. In this paper, mining-induced mechanical behaviors under three mining layouts have been simulated in the laboratory to investigate the effects of mining layouts on the deformation and strength of coal. Furthermore, the coal failure mechanism under different mining layouts is analyzed microscopically. The experimental results indicate that the stage characteristics of the coal deformation are obvious. Under the serial action of non-pillar mining, top-coal caving and protected coal seam mining layouts, the values of radial deformation, volume strain and Poisson’s ratio increase, while the peak strength and deformation modulus decrease at the same buried depth, and the peak strength under non-pillar mining, top-coal caving and protected coal seam mining is about 3.0, 2.5 and 2.0 times of the initial confining pressure, respectively. The results also indicate that the trend of the coal deformation decreases with the increase of the buried depth under the same mining layout, while the strength and deformation modulus increase, and the failure mechanism under three mining layouts is dominated with shear/tensile failure.

Modelling study for assessment of strata behaviour in bord and pillar working under soft floor condition

Safe and successful mining operation in bord and pillar workings under soft floor conditions requires a proper understanding of strata behaviour for better planning of mining layouts and selection of suitable mining horizon for better strata control and management of conditions arising due to excessive roof–floor convergence in the workings. This paper illustrates a modelling approach to assess the caving behaviour of strata, stress concentration, and roof–floor reactions in a depillaring bord and pillar working of Singareni coalfields in India. Assessment of floor heaving and roof–floor convergence in junctions of advance galleries is conducted with progressive goaf exposure. The calibrated model is used to predict the strata behaviour and roof–floor reactions in another depillaring panel. The modelling study has been helpful in better understanding of strata control issues for a confident decision making to ensure better safety and productivity of mine workings.

How seismic has helped to change coal mining in China

Coal is the main source of energy in China and accounts for over 65% of the country’s total energy consumption. China’s coal production is the largest in the world and its reserves rank third. Geological reports used for coal mine design and mining production in the past (before 1991, many mines operated without a seismic survey) could only determine faults with displacement larger than 30 m. Such reports fell far below the modern standard needed for mine design and extraction. Because of the poor precision of these geological reports, some mining layouts were unsuitable. Some tunnels and mines have flooded when unexpected geological structures have been encountered. Aware of the enormous economic loss caused by geological unknowns and the potential of high resolution seismic technology, the National Energy Investment Corporation issued a policy document (No.612) in 1991. It required that a seismic survey must be carried out in a coal mine area before any production plan is drawn up. Mining without a pre-production seismic report was forbidden. As a result, the new regulation promoted the application of high-resolution seismic surveys for coal mine construction and production, and marks a landmark in the history of seismic technology in China’s coal industry. From 1991 to 1993, all the seismic surveys were 2D, but it was soon found that the geological reports using 2D were not good enough to meet the needs of coal mine design and production. The first 3D survey in a coal mining area was carried out at Xieqiao coalmine for the Huai Nan Bureau of Mining in 1993. Since then, 3D surveys have been rapidly adopted for coal mines in China. Up to now, 3D surveys account for 95% of all coal mine seismic with 2D surveys making up only 5%. By the end of October 2003, 350 3D surveys projects had been completed covering an area of 600 km2. It has shown that the correct rate of faults with displacement larger than 5 m and caved pillars with a diameter bigger than 20 m verified by seismic survey is over 85% [1]. The detailed geological results have played an important role in optimizing the lay-out of mines. They can also prolong a mine’s production life, improve the safety of the operation, and deliver outstanding economic benefits to coal mining companies in China.

Construção de um modelo computacional para o circuito de ventilação da Mina Esperança

A ventilação em uma mina tem como principal objetivo o fornecimento de um fluxo de ar puro a todos os locais de trabalho em subsolo, em quantidades suficientes para assegurar as condições de higiene e segurança dos trabalhadores. A análise da eficiência ou do dimensionamento de um circuito de ventilação pode ser feita por meio de técnicas diretas de análise (algoritmo de Hardy Cross e Leis de Kirchhoff). Essas técnicas são extremamente trabalhosas quando se dispõe de um circuito de muitas malhas. Para uma análise mais detalhada ou previsão de mudanças no circuito de ventilação, empregam-se técnicas de simulação computacional. Essas técnicas foram utilizadas para a construção de um modelo computacional da distribuição do fluxo de ar para a Mina Esperança (SC), tendo como objetivo a adequação do atual circuito de ventilação a NR-22 e o aumento da quantidade de ar fornecida a cada painel em lavra para 2000 m³/min. Na construção do modelo foram utilizados dados de vazão, diferença de pressão estática, geometria das galerias e as características dos ventiladores. Esses dados, correlacionados pelo simulador, indicaram valores de vazão e pressão compatíveis aos medidos na mina, com diferenças entre os valores simulados e medidos de até 20%, sendo essa diferença adotada, pela equipe de trabalho, para validação dos modelos computacionais. De posse do modelo validado, estudaram-se diversos cenários de lavra futura, antevendo os valores de vazão e pressão a serem encontrados. Portanto as técnicas computacionais para a análise de redes de fluxo comprovaram ser uma importante ferramenta de projeto, diminuindo custos e racionalizando os recursos disponíveis.