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Ove Stephansson - One of the best experts on this subject based on the ideXlab platform.
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World Stress Map Database as a Resource for Rock Mechanics and Rock Engineering
Geotechnical and Geological Engineering, 2012Co-Authors: Arno Zang, Ove Stephansson, Oliver Heidbach, Silke JanouschkowetzAbstract:Knowledge of the in situ stress state is of key importance for Rock Engineering. We inform the reader about the World Stress Map (WSM) database and its application to Rock mechanics and Rock Engineering purpose, and in particular the orientation of maximum horizontal stress. We discuss the WSM and the quality ranking system of stress orientation data. We show one example of discrete-measured and computed-smoothed stress orientations from central and northern Europe with respect to relative plate velocity trajectories. We give first insights into ongoing development of a second, more Quantitative World Stress Map database which compiles globally Rock-type specific stress magnitudes versus depth. We discuss the vertical stress component, and the lateral stress coefficient versus depth for different Rock types. We display stress magnitudes in 2D and 3D stress space, and investigate stress ratios in relation to depth, lithology and tectonic faulting regime.
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fundamentals of discrete element methods for Rock Engineering theory and applications
2007Co-Authors: Lanru Jing, Ove StephanssonAbstract:This book presents some fundamental concepts behind the basic theories and tools of discrete element methods (DEM), its historical development, and its wide scope of applications in geology, geophysics and Rock Engineering. Unlike almost all books available on the general subject of DEM, this book includes coverage of both explicit and implicit DEM approaches, namely the Distinct Element Methods and Discontinuous Deformation Analysis (DDA) for both rigid and deformable blocks and particle systems, and also the Discrete Fracture Network (DFN) approach for fluid flow and solute transport simulations. The latter is actually also a discrete approach of importance for Rock mechanics and Rock Engineering. In addition, brief introductions to some alternative approaches are also provided, such as percolation theory and Cosserat micromechanics equivalence to particle systems, which often appear hand-in-hand with the DEM in the literature. Fundamentals of the particle mechanics approach using DEM for granular media is also presented. Presents the fundamental concepts of the discrete models for fractured Rocks, including constitutive models of Rock fractures and Rock masses for stress, deformation and fluid flow Provides a comprehensive presentation on discrete element methods, including distinct elements, discontinuous deformation analysis, discrete fracture networks, particle mechanics and Cosserat representation of granular media Features constitutive models of Rock fractures and fracture system characterization methods detaiing their significant impacts on the performance and uncertainty of the DEM models
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the role of hydromechanical coupling in fractured Rock Engineering
Hydrogeology Journal, 2003Co-Authors: Jonny Rutqvist, Ove StephanssonAbstract:This paper provides a review of hydromechanical (HM) couplings in fractured Rock, with special emphasis on HM interactions as a result of, or directly connected with human activities. In the early 1960s, the coupling between hydraulic and mechanical processes in fractured Rock started to receive wide attention. A series of events including dam failures, landslides, and injection-induced earthquakes were believed to result from HM interaction. Moreover, the advent of the computer technology in the 1970s made possible the integration of nonlinear processes such as stress–permeability coupling and Rock mass failure into coupled HM analysis. Coupled HM analysis is currently being applied to many geological Engineering practices. One key parameter in such analyses is a good estimate of the relationship between stress and permeability. Based on available laboratory and field data, it was found that the permeability of fractured Rock masses tends to be most sensitive to stress changes at shallow depth (low stress) and in areas of low in-situ permeability. In highly permeable, fractured Rock sections, fluid flow may take place in clusters of connected fractures which are locked open as a result of previous shear dislocation or partial cementation of hard mineral filling. Such locked-open fractures tend to be relatively insensitive to stress and may therefore be conductive at great depths. Because of the great variability of HM properties in fractured Rock, and the difficulties in using laboratory data for deriving in-situ material properties, the HM properties of fractured Rock masses are best characterized in situ.
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Rock stress and its measurement
1997Co-Authors: Bernard Amadei, Ove StephanssonAbstract:Introduction. Estimating in-situ stresses. Methods of in-situ stress measurement. Hydraulic methods. Relief methods. Jacking methods. Strain recovery methods. Borehole breakout methods. Case studies and comparison between different methods. Monitoring of stress change. The state of stress in the earth's crust: from local measurements to the world stress map. Using stresses in Rock Engineering, geology and geophysics. Appendices.
E.t. Brown - One of the best experts on this subject based on the ideXlab platform.
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reducing risks in the investigation design and construction of large concrete dams
Journal of rock mechanics and geotechnical engineering, 2017Co-Authors: E.t. BrownAbstract:Abstract An overview of the GeoSafe 2016 Symposium topic is provided using the example of large concrete dams for purposes of illustration. It is essential that the risks associated with large dams be evaluated rigorously and managed proactively at all stages of their lives so that the risk of failure remains As Low As Reasonably Practicable (ALARP). Rock Engineering features of large concrete dams that require particular attention, assessment and monitoring during the investigation, design, construction, initial filling, in-service operation, and subsequent repair and upgrade stages of the lives of concrete dams are identified and illustrated by examples from recorded experiences. A number of major concrete dam failures, including that of the St. Francis dam, California, U.S.A., in 1928, have led to significant developments in Rock mechanics and Rock Engineering knowledge and techniques, as well as in dam design and review processes. More recent advances include a range of analytical, numerical modelling, probabilistic, reliability, failure mode and risk assessment approaches.
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risk assessment and management in underground Rock Engineering an overview
Journal of rock mechanics and geotechnical engineering, 2012Co-Authors: E.t. BrownAbstract:This paper attempts to provide an overview of risk assessment and management practice in underground Rock Engineering based on a review of the international literature and some personal experience. It is noted that the terminologies used in risk assessment and management studies may vary from country to country. Probabilistic risk analysis is probably the most widely-used approach to risk assessment in Rock Engineering and in geotechnical Engineering more broadly. It is concluded that great potential exists to augment the existing probabilistic methods by the use of Bayesian networks and decision analysis techniques to allow reasoning under uncertainty and to update probabilities, material properties and analyses as further data become available throughout the various stages of a project. Examples are given of the use of these methods in underground excavation Engineering in China and elsewhere, and opportunities for their further application are identified.
J A Hudson - One of the best experts on this subject based on the ideXlab platform.
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design methodology for the safety of underground Rock Engineering
Journal of rock mechanics and geotechnical engineering, 2012Co-Authors: J A HudsonAbstract:Abstract In order to optimise the safety of underground Rock Engineering construction and the long-term security of the resultant facilities, it is necessary to have a knowledge of the likely hazards. These risks or hazards fall into the four categories of “known beforehand and relatively easily addressed”, “known beforehand and not easily addressed”, “not known beforehand and relatively easily addressed”, and “not known beforehand and not easily addressed”. This paper describes how these four types of hazard can be incorporated into a design methodology approach, including the process by which the relevant mechanical Rock mass parameters can be recognised for modelling and hence predictive purposes. In particular, there is emphasis on the fact that information and judgement are the keys to safety—whether the hazards are known or unknown before construction proceeds.
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specifying the information required for Rock mechanics modelling and Rock Engineering design
International Journal of Rock Mechanics and Mining Sciences, 2010Co-Authors: Xiating Feng, J A HudsonAbstract:Abstract Following two previous papers in which we discussed the ways ahead for Rock Engineering design methodologies, and presented two updated flow charts, this paper discusses how to establish the necessary quality and quantity of information required for Rock Engineering modelling and design. We demonstrate how different types of information are required by the different modelling and design methods, via their required inputs and constraints (a corollary being that a ‘standard site investigation’ is not appropriate) and that the degree of co-operation between the site investigation personnel and the modelling and design personnel is a crucial component. A five step procedure for establishing the required information is recommended. Two illustrative Rock slope case examples (one ‘simple’, one ‘complicated’) demonstrate the different modelling methods used, the type of information that was obtained for the modelling and design, with the results and conclusions. The paper illustrates the importance of understanding and establishing the necessary information requirements and ensuring that this information is in fact obtainable and obtained.
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updated flowcharts for Rock mechanics modelling and Rock Engineering design
International Journal of Rock Mechanics and Mining Sciences, 2007Co-Authors: J A Hudson, Xiating FengAbstract:In an earlier paper, the ways ahead for Rock Engineering design methodologies were discussed. In this paper, following an overview of earlier approaches, we present two updated flowcharts: one for Rock mechanics modelling in which the modelling options are outlined; and one for Rock Engineering design in which the three phases of overall assessment, initial design and final design are incorporated. We outline the steps necessary and the principles involved in utilising the flowcharts, especially the appropriateness of the modelling methods for different circumstances together with the integration of methods. Particular emphasis is placed on the cycling through feedback and final design. We demonstrate the procedure with three illustrative case study examples representing the range of complexity: a conventional tunnel, the design and construction of the underground powerhouse for the Shuibuya hydro-electric project in Hubei Province, China, and designing a radioactive waste repository. The first and third case examples are presented briefly: the first because of its relative simplicity; the third because of its relative complexity. The second case of the powerhouse design and construction is presented at greater length because it clearly illustrates the application of the flowcharts.
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the ways ahead for Rock Engineering design methodologies
International Journal of Rock Mechanics and Mining Sciences, 2004Co-Authors: Xiating Feng, J A HudsonAbstract:Abstract In this paper we discuss the future of Rock Engineering design methodologies within the framework of the eight current and potential basic design approaches. We note that many Rock Engineering projects are on the limit of precedent practice, involving large scales, increasing costs, enhanced environmental awareness and the need to understand and predict the consequences of coupled mechanisms involving stress, water, heat and chemical reactions. At the same time, Rock mechanics modeling is also becoming more complex and many more component elements and mechanisms can now be included in the numerical codes. Thus, because both the projects and the modeling are becoming more sophisticated, yet it may not be possible to obtain the necessary site information to support all the required input data for modeling, there is a need to consider how a design approach can be developed that integrates the current methods and includes those methods that are not based on exact 1:1 mapping between the problem geometry/mechanisms and the model. Our emphasis, therefore, is on development of the integrated design approach and the ‘intelligent’ methods. We also discuss how a virtual laboratory and the Internet can support these developments. An illustrative design case history of the shiplock slopes at the Threee Gorges Dam project in China is included. The paper concludes with nine specific points.
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numerical methods in Rock mechanics
International Journal of Rock Mechanics and Mining Sciences, 2002Co-Authors: Lanru Jing, J A HudsonAbstract:The purpose of this CivilZone review paper is to present the techniques, advances, problems and likely future development directions in numerical modelling for Rock mechanics and Rock Engineering. ...
Resat Ulusay - One of the best experts on this subject based on the ideXlab platform.
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geotechnical and geoenvironmental characteristics of man made underground structures in cappadocia turkey
Engineering Geology, 2003Co-Authors: Omer Aydan, Resat UlusayAbstract:Underground cities and semi-underground settlements, most of which are 1500 years at least, exist in the Cappadocia Region of Turkey. These man-made Rock structures are carved in soft tuffs and the best examples of long-term performance of man-made structures in the field of Rock Engineering. The tuffs also have good thermal isolation properties to be used as housing and storage of foods. In this article, the authors are only concerned with physical and short-term mechanical characteristics due to the wide-spectrum of the theme and the in situ characterization of the Cappadocia tuffs, and the results of investigations are presented. In addition, a critical overview on possible Engineering geological problems at Cappadocia with mechanical aspects of historical and modern Rock structures and their implications in Rock Engineering is made. From the experimental results in the field, it is evident that the Engineering characteristics of these Rocks do not show significant changes in vertical and horizontal directions. However, they are prone to atmospheric conditions. In addition, temperature and humidity measurements at different floors of the underground cities and various parts of semi-underground settlements indicated that variations in climatic conditions of the openings are very small when compared to those outside the ground surface.
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an application of fuzzy sets to the geological strength index gsi system used in Rock Engineering
Engineering Applications of Artificial Intelligence, 2003Co-Authors: H Sonmez, C Gokceoglu, Resat UlusayAbstract:Abstract Characterization of Rock masses is one of the fundamental aspects of Rock Engineering. Particularly, as a Rock mass characteristic, determination of the strength of closely jointed Rock masses is difficult since the size of representative specimens including discontinuities is too large for laboratory testing. This difficulty can be overcome by using the Hoek–Brown empirical failure criterion in conjunction with the Geological Strength Index (GSI) Classification System. However, characterization of Rock masses and determination of their strength may involve some uncertainties due to their complex nature. The fuzzy set theory is one of the tools to handle such uncertainties. This paper describes the application of fuzzy set theory to the GSI System by incorporating judgement and experience of practising engineers. For the purpose, the original GSI System and its modified form were defined by fuzzy sets, and Mamdani fuzzy algorithm was constructed using 22 “if–then” rules for evaluating discontinuity parameters and their ratings considered in the GSI System. In addition, slope instabilities in heavily jointed Rock masses selected from two open pit mines in Turkey were back analysed and the results were evaluated to demonstrate and to check the performance of this approach.
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assessment of Rock mass strength for underground excavations
International Journal of Rock Mechanics and Mining Sciences, 1997Co-Authors: Omer Aydan, Resat Ulusay, T KawamotoAbstract:Abstract When the stability of underground openings is assessed, one must concern with local and global failure modes. Local failures may take place as long as Rock blocks are kinematically movable into openings while global failure modes are associated with the stress state and the strength of Rock mass surrounding openings. This fact is always confused in underground Rock Engineering. First, the authors briefly describe several approaches how to assess the strength of Rock masses together with some new proposals for underground excavations. Then, the estimations by these methods are compared with each other as well as with experimental data. Finally, the validity of these methods are discussed and some recommendations are made for practical applications.
Hadi Bejari - One of the best experts on this subject based on the ideXlab platform.
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application of fuzzy set theory to Rock Engineering classification systems an illustration of the Rock mass excavability index
Rock Mechanics and Rock Engineering, 2010Co-Authors: Jafar Khademi Hamidi, Kourosh Shahriar, Bahram Rezai, Hadi BejariAbstract:The characterization of Rock masses is one of the integral aspects of Rock Engineering. Over the years, many classification systems have been developed for characterization and design purposes in mining and civil Engineering practices. However, the strength and weak points of such rating-based classifications have always been questionable. Such classification systems assign quantifiable values to predefined classified geotechnical parameters of Rock mass. This results in subjective uncertainties, leading to the misuse of such classifications in practical applications. Fuzzy set theory is an effective tool to overcome such uncertainties by using membership functions and an inference system. This study illustrates the potential application of fuzzy set theory in assisting engineers in the Rock Engineering decision processes for which subjectivity plays an important role. So, the basic principles of fuzzy set theory are described and then it was applied to Rock mass excavability (RME) classification to verify the applicability of fuzzy Rock Engineering classifications. It was concluded that fuzzy set theory has an acceptable reliability to be employed for all Rock Engineering classification systems.
