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By S. J. Bluhm

Recommendations are given for the design of multi-stage spray chambers in which air flows horizontally through water sprays. A detailed description is given of one such spray chamber at Hartebeestfontein gold mine that is used for bulk cooling of the incoming ventilation air, and that has been constructed according to these recommendations. A method for predicting the performance parameters of horizontal multi-stage spray chambers is given, and the method is illustrated with some examples. The method is equally applicable to spray chambers in which the water, rather than the air, is cooled.

Jan 1, 1979

By R. T. White, A. Higginson, M. Phil

Samples of water that had been collected underground from eight gold mines in South Africa were subjected comprehensive analysis of the quality of the waters, and their corrosivity on mild steel was measured by the laboratory techniques of extrapolation from Tafel plots and of polarization resistance. The results indicate that, if such factors as pH, Langelier index, and degree of aeration are beyond certain specified limits, the corrosivity ofthe water is affected. The applicability of the corrosivity index in predictions ofthe degree corrosion is questioned. Suggestions are included for future work involving the fundamental characterization of the corrosivity of mine waters.

Jan 1, 1983

By E. J. Margi

Deep gold exploration such as is used for Witwatersrand gold deposits is both expensive and time-consuming. This paper provides quantitative guidelines as to the economic optimum number of boreholes and deflections within each borehole for a certain reef characterized by its variability pattern and depth below surface in order to maximize the level of confidence for a fixed drilling budget or to minimize the total drilling cost for a given level of confidence. Portions of the Basal, Vaal, and Elsburg Reefs that show a wide range of variability (sample logarithmic variances of 0,63, 1,05, and 2,06 respectively) are examined at depths below surface ranging from 1000 m to 4000 m over a simulated mining property covering 7000 ha (7000 m by 10000 m). It is concluded that four intersections per borehole are optimum in al the cases considered, which cover the majority of current Witwatersrand exploration, with the exception of the highly variable Elsburg Reef at depths of 1000 m and 2000 m, where boreholes with one and two intersections respectively should be preferred.

Jan 1, 1987

By E. H. van Niekerk

The production of high-strength Iow-alloy (HSLA) steels containing either niobium or vanadium as the principal micro-alloying element is discussed, including recent developments in steelmaking practice that have had a great effect on the development of HSLA steels; strengthening mechanisms, as well as the principles of thermomechanical treatment during controlled rolling on a hot-strip mill; and the results of production heats with various amounts of micro-alloying elements.

Jan 1, 1984

By H. H. Bird

The crux of reliable estimates of ore reserves lies in a comprehension of the related geological events and their controls on the formation and distribution of the economic mineralization, and on the rock types, lithology, and structures. Furthermore, mine geometry is based on the shape of the ore body, the types and distribution of the economic minerals, and the ground conditions. Asian mining The Institution of Mining and Metallurgy has been invited to organize an international conference on the occasion of the Asian mining 81 international exhibition.

Jan 1, 1980

By J. P. Hoffman, A. S. M. de Jesus

Additions of boron have been found to increase the hot workability of stainless steels. Boron forms complex chromium-iron borides, primarily at grain boundaries but also on delta-ferite stringers. This paper describes how a nuclear technique based on the track-etch method was used to distinguish between borides and chromium carbides on grain boundaries and to investigate the distribution of boron in stainless steels. The method was found to be sensitive for boron, and made it possible for boron precipitates to be identified on grain boundaries and interphase boundaries.

Jan 1, 1989

By R. R. Mankowski

The work described here attempts to underscore the importance of the time lag between the end of a loading phase and the instant a winding drum begins its acceleration phase. Traces generated from a computer-simulation model show that the amplitude of the stress oscillations occurring in mine hoisting cable during the constant velocity-of-ascent phase is a direct result of the temporal sequence employed between the loading and the raising phases. While current and early literature indicates that extensive work has been undertaken on the isolated effects of these two independent sequences, the literature does not appear to contain any documented evidence to suggest an optimal control or interfacing between these two dynamic regimes.

Jan 1, 1995

The peak in Sulphur price late 2008 caused again intensified investigation into the decomposition of sulphates and spend acid. One option is the recycling of sulphur from spend acid, which already started more than 40 years ago in the field of spend acid from organic processes in refineries and acrylic glass manufacturing. Since this acid couldn't be neutralized and discarded due to high organic contents, another source of SO2 to produce sulfuric acid is the decomposition of metal sulfates. The decomposition of metal sulfates was investigated at the next peak in Sulphur price in the 80?s. The first major scale pilot tests and studies of gypsum decomposition were carried out for clients in Florida. The decomposition of gypsum was quite often mainly influenced by the strategic decision of some countries to get own and independent acid production. In other cases the industry doesn?t have enough space to dump the gypsum. Therefore the company was also forced to convert the gypsum into ?saleable? products to avoid these residues. Other projects were made for the recycling of iron-sulfates from the pigment industry. The motivations for these projects were not only given by acid price. For the German pigment industry it was no longer permitted in the 80?s to dump the iron sulphate residues into the sea. These regulations forced the industry to develop new technology, which allows converting of the FeSO4-residues into iron oxide and acid. Therefore economical and mainly environmental factors influenced the decision of the companies to develop and to build these plants. Beside the above mention iron- and calcium-sulphates many other process exist, which produce metal sulphates as an intermediate product. These cases are not forced by environmental or strategic factors. In cases like Ni, Co or Mn-decomposition the main product of the plant is treated in the decomposition plant and later on used as ferrous-alloys. These final products are higher in price compared to e.g. CaO, which exclude the high-energy consumption for the endothermic chemical decomposition reaction. The reaction of SO2 generation based on acid or sulfate decomposition takes place in the range of 1000°C. The energy demand of the endothermic reaction is considerable and leads due to the high fuel-combustion off-gas stream to a diluted SO2 gas. Energy prices are usually increasing at the same time like sulphur. Sulphuric Acid based on decomposition is therefore more expensive than as acid based on sulphur combustion. The paper describes fluid bed technology and possible process concepts for decomposition plants. Additionally the thermodynamic background of the decomposition process and the main influence factors are provided to receive a better understanding of this technology.

Jan 1, 2009

The peak in Sulphur price late 2008 caused again intensified investigation into the decomposition of sulphates and spend acid. One option is the recycling of sulphur from spend acid, which already started more than 40 years ago in the field of spend acid from organic processes in refineries and acrylic glass manufacturing. Since this acid couldn't be neutralized and discarded due to high organic contents, another source of SO2 to produce sulfuric acid is the decomposition of metal sulfates. The decomposition of metal sulfates was investigated at the next peak in Sulphur price in the 80?s. The first major scale pilot tests and studies of gypsum decomposition were carried out for clients in Florida. The decomposition of gypsum was quite often mainly influenced by the strategic decision of some countries to get own and independent acid production. In other cases the industry doesn?t have enough space to dump the gypsum. Therefore the company was also forced to convert the gypsum into ?saleable? products to avoid these residues. Other projects were made for the recycling of iron-sulfates from the pigment industry. The motivations for these projects were not only given by acid price. For the German pigment industry it was no longer permitted in the 80?s to dump the iron sulphate residues into the sea. These regulations forced the industry to develop new technology, which allows converting of the FeSO4-residues into iron oxide and acid. Therefore economical and mainly environmental factors influenced the decision of the companies to develop and to build these plants. Beside the above mention iron- and calcium-sulphates many other process exist, which produce metal sulphates as an intermediate product. These cases are not forced by environmental or strategic factors. In cases like Ni, Co or Mn-decomposition the main product of the plant is treated in the decomposition plant and later on used as ferrous-alloys. These final products are higher in price compared to e.g. CaO, which exclude the high-energy consumption for the endothermic chemical decomposition reaction. The reaction of SO2 generation based on acid or sulfate decomposition takes place in the range of 1000°C. The energy demand of the endothermic reaction is considerable and leads due to the high fuel-combustion off-gas stream to a diluted SO2 gas. Energy prices are usually increasing at the same time like sulphur. Sulphuric Acid based on decomposition is therefore more expensive than as acid based on sulphur combustion. The paper describes fluid bed technology and possible process concepts for decomposition plants. Additionally the thermodynamic background of the decomposition process and the main influence factors are provided to receive a better understanding of this technology.

Jan 1, 2009

By S. Tu, Y. Yuan, H. Wei, Z. Chen, M. Jia

"To reduce production costs and increase efficiency in ageing coal mines, a system that utilizes two shearers in a fully mechanized longwall working face is proposed. Using theoretical and engineering experience, three issues pertaining to the system were determined: (a) the two-shearer mining technique; (b) matching and modifying the equipment; (c) and coal-cutting task allocation for each shearer. Two mining processes are proposed, with the two shearers travelling in either the same or opposing directions. To avoid breakage of chains and pan extrusion of the armoured face conveyor (AFC), the length of the AFC ‘snake’ was controlled. To ensure continuous cutting and transporting of coal, the cross-sectional dimensions of the AFC were checked and the shearer closer to the head drive was modified. Based on the assumption of equal cutting times for each shearer, the meeting position of the two shearers was obtained by using a theoretical model of mining task allocation. Application of this technique at No. 2 Jining Mine, China, has shown remarkable benefits: daily production capacity was increased by 54% and personnel efficiency was improved by 33 t/d per person. IntroductionAll coal mines aim to increase the unit output of the working face to reduce mining costs and improve the economic efficiency of the operation. To achieve this goal, a production model known as one mining face of the mining area has been adopted by most Chinese coal mines (Hu, Meng, and Zhu, 2008; Zhang, Zhang, and Wang, 2000). Under these conditions, the main technical approaches to maximize the output are increasing the width of the working face (Qu, Xu, and Xue, 2009) and accelerating the advancing speed (Robbins, 2000). In coalfields with shallow seams, the width of a fully mechanized face exceeds 300 m (Ju and Zhu, 2015; Fu, Song, and Xing, 2010); in coalfields with deep seams, the width of the face is usually greater than 240 m (Liu et al., 2016; Li et al., 2013). The term ‘super-long working face’ was proposed to describe working faces with a width of over 240 m (Zhao and Song, 2016; Xu et al, 2007) in China. To support these long working faces with rapid advancing speeds, high-powered mining equipment is required (Kulshreshtha and Parikh, 2001, 2002; Tu et al., 2009; Mishra, Sugla,and Singha, 2013). This is easily achieved in newly built mines, but is not a good choice for ageing mines because of the low return on a high investment on account of the limited remaining resources. It is therefore difficult for ageing mines to significantly increase their unit output with the existing mining equipment. This study focused on this problem: two shearers were applied to a longwall fully mechanized working face (LFMWF) to achieve increased unit output."

Oct 1, 2018

By S. R. Xie, S. Gong, E. P. Li, S. S. He, Y. J. Sun, S. J. Li

"Based on the complicated geological production conditions and abnormal strata behavior of the fully mechanized caving face No. 102 in the Xinyang Coal Mine, we analyze the breaking and forming process of distinguishing key block structures in close spaced coal seams. This analysis establishes an integrated mechanical model of these distinguishing structures. Furthermore, the horizontal force TAB generated by downward key blocks A and B is quantified, as is the Pressure PG exerted by key block B on caved gangue. Finally, the interaction mechanism is revealed. Analysis of the results using Mathematica reveal the following: 1. Both TAB and PG exhibit approximately inverse relationships to coal pillar width b; 2. TAB exhibits an approximately exponential relationship with mining height M of which the base is greater than 1; 3. PG exhibits an approximately arctangent relationship with mining height M. Combining these results with field observations, we conclude that the area in the vicinity of supports 100#–120# in the upper area of working face No. 102 is the likely zone of abnormal strata behavior. Thus, this area was classified as a key control area. Based on these results, the graded support control technique is proposed. Application of this technique in the field resulted in a reduction in the rate of hydraulic support system malfunction from 47% to 7% in the key control area. In addition, during times of periodic mining pressure, the roof caving height value never exceeded 0.3 m and the maximum spalling depth never exceeded 0.2 m. Overall, the results indicate that this new technique has markedly increased the stability of surrounding support rock material. IntroductionClose-spaced coal seams are widely distributed in China, and mining proceeds from the uppermost to the lowermost seam (Zhang et al., 2008). In the case of coal seams in close proximity, a particular set of risk factors becomes pertinent. These include disturbance of lower seams during the mining of overlying ones and the decrease in mechanical stability of lower coal seams following repeated movement of key blocks in main coal seam roofs. This inevitably results in behaviour such as heavy wall spalling and support damage to fully mechanized caving faces in lower-lying coal seams, which necessitates a significantly increase in the measures to support surrounding rock material (Zhang et al., 2010; Huang et al., 2013; Xie et al., 2013)."

Jan 1, 2016

By Sabine Verryn, Johan de Villiers

"Through the application of the Rietveld method, X-ray diffraction analysis has developed into a fully quantitative method for phase analysis. The Rietveld method itself has progressed from an unstable method that required constant operator intervention to a stable and robust method suited even for routine analysis. The method however, requires a good initial calibration and periodic checks on its precision and accuracy.Several examples from minerals processing, pyrometallurgy, and materials science show the strengths and applicability of the method. The limitations and sources of error are also discussed.1. IntroductionDiffraction of X-rays by matter has been used for more than 80 years, initially to elucidate the structure of crystalline matter, and to investigate the bonding between atoms. The first development of powder diffraction cameras and the later development of X-ray diffractometers saw the development of methods to identify phases and to try to quantify them in mixtures. A comprehensive database and search-match techniques have been developed over the ensuing years. Effective and accurate quantification had to wait for the so-called Rietveld' analysis where the total diffraction pattern is used and where the crystal structure data for the constituent phases are needed as input. Overlapping of diffraction peaks of different phases is handled without difficulty and reliable results can be obtained in spite of this occurrence.The development of methods for structure analysis from powder data has also progressed rapidly and more and more complex structures are being solved from first principles, i.e. without knowledge of unit cell or space group data. Because of the ease of use of the Rietveld method, it is finding increased application in metallurgy, especially in the quantification of phases of importance in minerals processing, in pyrometallurgical processes, and in materials characterization. This study will examine the principles of the Rietveld method, its application in metallurgy, and finally also the common pitfalls that need to be avoided.2. Rietve1d AnalysisAs the Rietveld method compares the experimental diffraction pattern with one calculated from known crystal structure data, the following data are needed:•,An XRD Pattern with as Iowa background as possible. This should have good resolution and high diffraction peak intensities. With modem X-ray detectors, this can be achieved in minutes rather than hours.•,Instrumental parameters such as goniometer radii and slit sizes are needed. These are the so-called ""Fundamental parameters"". They are used to calculate the shapes of the resultant diffraction peak profiles that are caused by the instrument. The parameters are used to correctly separate the instrumental effects on the diffraction pattern from the sample effects."

Jan 1, 2014

By T. G. Maepa

"The creation of mine excavations alters the stress distribution in the surrounding rock mass. In modern mining, resin-grouted rockbolts are used as a means of support in order to redistribute stresses and reestablish equilibrium in the rock mass. The success of resin-grouted rockbolting depends on the design of the system and the correct installation of the support units.The support design and rockbolt installation procedure at a platinum mine in the Bushveld Complex were investigated. A number of issues that resulted in poor installation were identified, including resin admixture, incorrect length and orientation of support holes, over- or under-spinning of the resin, and incorrect rockbolt tensioning. The support design used at the mine was reviewed and its limitations identified. A number of recommendations were made for optimizing the support design by reducing the diameter of the drill bit and reducing the length of the support holes. These changes will enable the mine to use different combinations of resin capsules. Implementation of the proposed changes will lead to a significant reduction in the cost of installation per support hole, as well as improve productivity and safety.IntroductionThe creation of any mine excavation disturbs the virgin state of stress in the Earth’s crust. This results in stress concentrations that interfere with the stability of the rock mass surrounding the excavation. It is essential to modify the internal behaviour of the rock mass surrounding excavations in order to reinforce the ground and stabilize excavations. Resin-grouted rockbolts are extensively used for this purpose. Esterhuizen (2014) stated that when effectively installed, the rockbolt exerts a clamping force and a bonding strength that keeps the rock mass together. This increases the cohesive strength of all discontinuities in the rock mass and enhances the stability of the excavation. Poorly designed and installed ground support is ineffective and constitutes a safety hazard. It is therefore crucial for every mine to ensure that any form of ground support is designed and installed correctly. This research evaluates the installation of resign-grouted rockbolts and identifies challenges and solutions for improved safety as observed at an operating hard rock mine. The support design used at the mine was reviewed and the design parameters optimized. The outcomes will enhance the efficiency of support and minimize the costs associated with the installation of resingrouted rockbolts."

Jan 1, 2017

By J. Abdollahisharif

Optimal cut-off grade is one of the most critical parameters in open-pit mine design because it defines the ore and waste and thus determines the maximum net present value possible from the mining operation. Although the algorithm presented by Lane (Choosing the optimum cut-off grade. Colorado school of Mines Quarterly, vol. 59, no. 4, 1964. pp. 811-829) is the most common one in the literature, it does assume constant capacities of the mine, processing, and refinery. In this paper, Lane's original algorithm has been modified to consider variable processing capacities in order to determine the optimal cut-off grade in open-pit mines. The new algorithm proposed here is compared to both Lane's original algorithm and to a previous modification that incorporated rehabilitation costs into the cut-off grade estimation. The algorithm proposed here that permits variable processing capacities is shown to be superior for the determination of optimal cut-off grade to both these previous versions. In addition, a computer-based program was developed in Microsoft Office Excel© to calculate the optimal cut-off grade as proposed here.

Jan 1, 2012

By H. Edinger

China?s engagement with the African continent has increased impressively in the past decade. Even though China is not the African continent?s largest stakeholder, the rapidly increasing engagement is evident in the huge number of Chinese migrants that have come to Africa in the wake of unprecedented trade and investment levels, as well as in increasing diplomatic and political interactions, which has taken most other commercial partners by surprise. All but four countries in Africa have adopted the ?One China?1 policy stance; and in so doing opened the door for new or strengthened commercial dealings with China, including increasing investments into Africa?s extractive industries. This has been particularly evident since the turn of the century, with a clear shift in China?s policy towards Africa elevating the continent in China?s foreign policy objectives. As such, Africa has become a strategic focus2 for Chinese outward bound and internationalizing companies, especially in the extractive industries. This planned shift in focus is based largely on geo-strategic and commercial needs and interests, rather than previous ideological ones.3

Jan 1, 2011

By D. E. Kraushaar

Ruhrkohle in West Germany evaluates and compares the net present values of long-term periods from its coal mines by a computer assisted long-term planning system. Two main parts of this system are computer programs for the prediction of: (a) mineable reserves and their distribution in longwall panels as a function of dependent geological variables; (b) daily outputs and costs of longwall panels as a function of dependent geo- logical, layout and operational variables. This paper describes the investigations, which ended in the above computer programs: ? the collection of information from past workings and their organization in databases; ? the statistical evaluation of the databases, and ? the resulting correlation formulas. The correlation formulas vary the mean dependent variables as a function of independent variables which can be indicated with high reliability for planning projects in the long run. The system thus serves the purpose of facilitating long-term planning and excluding biased individual judgement of local planning staffs.

Jan 1, 1987

By V. E. Ross

A computer program was developed that incorporates a novel analysis of the behaviour of the froth in full-scale cells to predict the performance of the froth over a wide range of operating conditions. The program has the distinct advantage that it can be easily implemented on a microcomputer, which allows rapid computation and processing of the results. The program utilizes experimental data obtained in flotation-plant and laboratory testwork to provide parameters for the froth model under an initial set of operating conditions. These parameters can then be used in conjunction with a model describing the transfer of material from the pulp to the froth to predict the performance of the cell when its dimensions and operating variables are changed during scale-up.

Jan 1, 1987

By S. A. Abdel Sabour

Strategic decisions in the mining industry are made under multiple technical and market uncertainties. Therefore, to reach the best possible decision, based on information available, it is necessary to integrate uncertainty about the input variables and model financial risk of the project?s merit measures. However, this provides few useful insights to decision-makers unless accompanied by modelling management responses to uncertainty resolutions. It is widely acknowledged that conventional decision-support methods based on static, no-change, discounted cash flow (DCF) techniques such as net present value (NPV) and internal rate of return (IRR) tend to provide inaccurate value estimates. This could mislead the strategic decision-making process and result in significant value losses. This paper aims to model financial risk related to uncertainty about market variables such as metal prices and foreign exchange rates. Other sources of risk that are related, for example, to geology and production costs are not considered in this work. The article outlines a flexible financial model that integrates uncertainty about market variables and management flexibility to react to uncertainty resolutions into mine project valuation using a real-options valuation technique based on Monte Carlo simulation. Significance of information generated from this simulation-based flexible valuation model to the strategic decision-making process is tested using an illustrative case study of a Canadian mining project. The project is a typical multi-metal, open pit mine that produces copper and gold. In this case, there are three uncertain market variables, which are: copper and gold prices and US$/CAN$ exchange rate. Financial valuations are carried out using both the conventional static DCF method and a flexible real-options model. In the flexible model, management flexibility to decide whether to go ahead with the next expansion or terminate production operations is integrated. Results show how the flexible financial model can enhance the decision-making process.

Jan 1, 2009

By F. L. D. Cloete, M. C. Coetzee

This study was aimed at a comparison of the efectiveness of a new axial-flow type of mixer impeller (the Prochem design) with the traditional inclined-blade turbine. The intended application of the mixers was in carbon-in-pulp plants for the extraction of gold from cyanide-leached pulps. The first part of the project involved water and ion-exchange resin, and measurement of the power drawn by the various sizes of impeller to fully suspend the resin. The rate of reaction between the resin and the solution was measured as a function of the power input to the mixer. In the second part of the project, use was made of activated carbon, silver cyanide solutions, and ore pulps. The rate of absorption of silver from the solutions and pulps was determined, as well as the rate of attrition of the activated carbon caused by the various impellers in clear water. The Prochem design of axial-flow impeller was shown to fully suspend solids at only one-quarter of the power requireabyan inclined-blade turbine of similar size. The axial-flow pattern produced was responsible for the more uniform vertical concentration profile of suspended beads produced by the Prochem design. These measurements verified the observations of other researchers that the rate of reaction is not affected by the ;design of impeller provided that al the solids are fully suspended. The Prochem design of impeller therefore achieved the same reaction rate as the conventional turbine at a quarter of the power input. The atrition rates of activated carbon could be correlated, in terms of the energy absorbed, by the same equation for al the impellers. Higher concentrations of activated carbon increased the amount of carbon fines produced. These results emphasize the importance of designing mixers for minimum power consumption.

Jan 1, 1989

By C. Zangerl, K. F. Evans, S. Loew

ABSTRACT: Settlements above fractured crystalline rock masses are rarely observed and in the past, geotechnical engineers would not expect substantial subsidence to occur in association with a deep tunnelling project. However, recent high precision levelling measurements along the Gotthard pass road in central Switzerland, have revealed up to 12 cm of subsidence along sections that pass several hundred metres above the Gotthard highway tunnel. Large-scale consolidation resulting from tunnel drainage and pore pressure changes in the rock mass are believed to be the contributing mechanism. This paper presents results from an extensive numerical modelling study focussing on the processes responsible for this subsidence. Results derived from 2-D discontinuum (i.e. distinct-element) and continuum (i.e. finite-element) modelling show that both discrete fracture deformation (i.e. fracture closure and shear) and poro-elastic consolidation of the intact rock matrix equally contribute to the observed magnitudes and shape of the surface subsidence trough. RÉSUMÉ: Des tassements aux dessus de massifs cristallins sont rarement observés et par le passé les géotechniciens ne prévoyait pas de subsidence significative associée avec des projets de tunnel profond. Cependant, de récentes campagnes de nivellement haute précision le long de la route du Col du Gotthard (Suisse centrale), ont mis en évidence des subsidences atteignant 12 cm sur des sections passant plusieurs centaines de mètres au-dessus du tunnel routier du Gotthard. Le mécanisme invoqué pour expliquer ce phénomène est la consolidation à grande échelle due au drainage du tunnel et aux variations de pression de pore dans le massif rocheux. Cet article présente les résultats d’une modélisation numérique intensive mettant l’accent sur les processus responsables pour la subsidence. Ces résultats obtenus grâce à des modèles 2-D discontinus (p. ex. éléments distincts) et continus (p. ex. éléments finis) montrent que la déformation sur des fractures discrètes (fermeture de fractures, cisaillement) ainsi que la consolidation poro-élastique de la roche intacte contribuent également aux magnitudes et aux géométries de subsidence observée en surface. ZUSAMMENFASSUNG: Beachtliche Oberflächensenkungen in einem kristallinen Gebirge, deren Ursache im Vortrieb eines mehrere hundert Meter tiefgelegenen Tunnels liegt, wurden bisher nicht erwartet und beobachtet. Dennoch wurden nach dem Bau des Gotthardstrassentunnels, entlang der Gotthardpassstrasse Oberflächensenkungen mit einem Maximalbetrag von 12 cm bei der Auswertung von Präzisions-Nivellements entdeckt. Dieser Maximalbetrag wurde in einem granitischen Gneis gemessen. Die örtliche Übereinstimmung zwischen dem maximalem Senkungsbetrag und dem maximalem Wasserzufluss zum Tunnel, und die zeitliche Abfolge von Tunnelbau und auftretenden Oberflächensenkungen lassen hydromechanisch gekoppelte Prozesse als Ursache dieser Gebirgsverformungen vermuten. In dieser Arbeit werden die Ergebnisse ausgedehnter prozessorientierter numerischer Simulationen präsentiert. Resultate aus den 2-D Diskontinuum (d.h. distinct-element) und Kontinuum (d.h. finite element) Simulationen zeigen, dass beide Verformungsmechanismen, d.h. an diskreten Brüchen und der intakten Gesteinsmatrix, gleichbedeutend für die beobachteten Senkungsbeträge und der Form des Setzungstroges verantwortlich sind.

Jan 1, 2003