Support Of Underground Excavations In Hard Rock

The safe and economical construction of tunnels, mines, and other subterranean works depends on the correct choice of support systems to ensure that the excavations are stable. These support systems should be matched to the characterstics of the rock mass and the excavation techniques adopted. Establishing the support requirements, designing support systems and installing these correctly are essential elements in safe underground construction. This is a comprehensive and practical work which also gives access to user-friendly computer programmes which enable the investigation and design of support techniques. Details on how to obtain this software are also included in the book.

Underground Excavations in Rock deals with the geotechnical aspects of the design of underground openings for mining and civil engineering processes.

Table of ContentsPreface............................................................................................. vForeword......................................................................................... vii1. An overview of rock support design........................................... 11.1 Introduction.................................................................. 11.2 Stages in mine development........................................... 1 1.2.1 Exploration and preliminary design................... 3 1.2.2 Mine design...................................................... 3 1.2.3 Early years of mining........................................ 4 1.2.4 Later years of mining........................................ 71.3 Support design.............................................................. 72. Assessing acceptable risks in design............................................ 82.1 Introduction.................................................................. 82.2 Factor of safety............................................................. 92.3 Sensitivity studies.......................................................... 102.4 The application of probability to design......................... 102.5 Probability of failure..................................................... 162.6 Problems to which probability cannot be applied............ 183. Evaluation of engineering geology data...................................... 203.1 Introduction.................................................................. 203.2 Engineering geological data collection........................... 203.3 Structural geological terms............................................ 213.4 Structural geological data collection.............................. 223.5 Structural geological data presentation.......................... 233.6 Geological data analysis................................................ 244. Rock mass classification.............................................................. 274.1 Introduction.................................................................. 274.2 Engineering rock mass classification.............................. 27 4.2.1 Terzaghi's rock mass classification..................... 28 4.2.2 Classifications involving stand-up time............... 29 4.2.3 Rock quality designation index (RQD)................ 30 4.2.4 Rock structure rating (RSR)............................... 314.3 Geomechanics classification.......................................... 344.4 Modifications to RMR for mining................................. 384.5 Rock tunnelling quality index, Q.................................... 394.6 Using rock mass classification systems.......................... 454.7 Estimation of in situ deformation modulus..................... 475. Shear strength of discontinuities................................................. 515.1 Introduction.................................................................. 515.2 Shear strength of planar surfaces................................... 51ii Support of underground excavations in hard rock5.3 Shear strength of rough surfaces.................................... 52 5.3.1 Field estimates of JRC....................................... 53 5.3.2 Field estimates of JCS....................................... 54 5.3.3 Influence of scale on JRC and JCS..................... 555.4 Shear strength of filled discontinuities........................... 565.5 Influence of water pressure............................................ 575.6 Instantaneous cohesion and friction............................... 576. Analysis of structurally controlled instability............................. 616.1 Introduction.......................................... 616.2 Identification of potential wedges........... 616.3 Support to control wedge failure............. 65 6.3.1 Rock bolting wedges............

Squeezing ground conditions can result in large scale deformation and instability of underground excavations in rock. In hard rock mines, squeezing ground conditions are often associated with the presence of dominant foliation and high stress with resulting deformation often exceeding the capacity of installed ground support. This can result in failure of ground support making the excavations non-operational. This thesis is a contribution to improved understanding of structurally defined squeezing mechanisms observed in underground hard rock mines. A comprehensive field campaign was undertaken in two mines where squeezing was a major ground control issue. This has allowed the development of a database comprised of 147 squeezing case studies. Reported information included drift configuration and orientation, deformation monitoring, rock mass characterization and the performance of ground support. The data were reviewed to identify the failure mechanisms and to quantify the influence of ground conditions, excavation orientation, and the performance of different support strategies. The distinct element method (DEM) was used to successfully reproduce the buckling mechanism resulting in squeezing and large deformations observed in mining drifts in the database. The developed methodology was implemented in 3D models and explicitly considered the role of foliation. Subsequently, a comprehensive strategy for explicitly modeling rock reinforcement using the DEM was developed and implemented in a series of 3D numerical models. The models were calibrated based on field testing of reinforcement and observations at the LaRonde Mine. They were used to investigate the impact of different reinforcement strategies and the time of installation of the support. The numerical results were in agreement with the field observations and demonstrated the practical implications of using yielding reinforcement elements. This was supported by field data where the use of yielding bolts reduced the drift convergence and rehabilitation. An analysis and interpretation of the field data and the numerical modelling investigations were used to provide tools for the assessment and mitigation of the anticipated deformation in squeezing ground. The developed strategies can be used to select optimal reinforcement options. The developed tools and procedures can be successfully used to manage large structurally controlled deformations in underground hard rock mines.

Underground Mining Methods presents the latest principles and techniques in use today. Reflecting the international and diverse nature of the industry, a series of mining case studies is presented covering the commodity range from iron ore to diamonds extracted by operations located in all corners of the world. Industry experts have contributed 77 chapters. This book is certain to become a standard for every practicing mining engineer and student alike. Sections include: General Mine Design Considerations, Room-and-Pillar Mining of Hard Rock/Soft Rock, Longwall Mining of Hard Rock, Shrinkage Stoping, Sublevel Stoping, Cut-and-Fill Mining, Sublevel Caving, Panel Caving, Foundations for Design, and Underground Mining Looks to the Future.

Surface and Underground Excavations – Methods, Techniques and Equipment (2nd edition) covers the latest technologies and developments in the excavation arena at any locale: surface or underground. In the first few chapters, unit operations are discussed and subsequently, excavation techniques are described for various operations: tunnelling, drifting, raising, sinking, stoping, quarrying, surface mining, liquidation and mass blasting as well as construction of large subsurface excavations such as caverns and underground chambers. The design, planning and development of excavations are treated in a separate chapter. Especially featured are methodologies to select stoping methods through incremental analysis. Furthermore, this edition encompasses comprehensive sections on mining at ‘ultra depths’, mining difficult deposits using non-conventional technologies, mineral inventory evaluation (ore – reserves estimation) and mine closure. Concerns over Occupational Health and Safety (OHS), environment and loss prevention, and sustainable development are also addressed in advocating a solution to succeed within a scenario of global competition and recession. This expanded second edition has been wholly revised, brought fully up-to-date and includes (wherever feasible) the latest trends and best practices, case studies, global surveys and toolkits as well as questions at the end of each chapter. This volume will now be even more appealing to students in earth sciences, geology, and in civil, mining and construction engineering, to practicing engineers and professionals in these disciplines as well as to all with a general or professional interest in surface and underground excavations.

Underground openings create various excavation-induced responses. The most noticeable response is the readily observed excavation damaged zone (EDZ) where the mechanical properties of the rock mass have been irreversibly altered, i.e., damaged. Within this damaged zone the stresses and displacements cannot be predicted using elastic theory. This damaged zone contains a region of reduced stresses and increased displacements and forms a rock mass ring that can contribute to the stability of the underground opening. This concept is well known and provided the stability of EDZ support ring is maintained, large underground excavations can be created at a great depth. However, predicting and quantifying the extent and properties of the rock mass mechanical damage that can occur in the EDZ has remained a challenge. The damage that occurs in the EDZ in typical strong rocks (ISRM Class R3 to R6) can be characterised as stress-induced and/or blast-induced fractures. These fractures can range from the millimetre to the metre scale. It is well known that the addition of cracks to a solid changes its mechanical properties and characteristics. Hence to quantify these changes both geometry and properties of the induced fractures must be known. Once these changes are quantified, the biggest challenge is translating these changes into rock mass mechanical properties. Recent developments with numerical methods have shown that discrete element modelling offers the most realistic methodology for estimating rock mass properties, provided the characteristics and geometry of the discrete fractures are known with confidence. The methodology, which has been termed as the Grain-based Model (GBM), can incorporate both intact blocks and discrete fractures. The GBM utilizes a voronoi tessellation scheme to simulate the microstructure of rocks by creating randomly composed blocks that are similar to the polygonal grains of intact rocks. The GBM can be calibrated to the conventional laboratory tests (UCS test, direct tension test and triaxial compression test) on intact rocks. It is shown that such calibration is not path dependent, i.e., calibrating to the direct tensile strength is able to predict the compressive strength. Once the GBM calibration with the intact properties was carried out, large-scale discrete fractures were added to the GBM to determine the effect of these fractures on the rock mass mechanical properties. To validate the GBM approach, several models were developed and the mechanical responses were compared to published results. The models increased in complexity from a single inclined fracture to two regular and uniformly spaced fracture sets. The responses from the GBM models were in good agreement with the results from the physical models. When the fractures are not uniformly spaced there is no simple means to establish the complex geometry of the fractures. At the Äspö Hard Rock Laboratory in Sweden, a unique experiment was carried out to establish the geometry of the excavation-induced and naturally occurring fractures found at the boundary of tunnel excavated by careful drill-and-blast technique. The fractures were measured at the mm scale. A methodology was developed to import the geometry of the fractures into the GBM. This model was then loaded to establish the mechanical properties. The results from the models were compared to the rock mass strength derived using the empirical Hoek-Brown failure criteria. The finding from the research demonstrates that the GBM and provides a reasonable approach to establish the rock mass strength at the tunnel scale. The methodology also provides an approach for establishing the effect of the blast-induced damage on the rock mass strength.

Provides practical solutions to the challenge of modeling and analyzing rock masses Consolidates a wealth of previously published technical papers on the subject and introduces previously unseen material This authoritative title is a key reference for any Geo-engineer. Rock masses differ considerably from man-made materials, and their properties can vary with location, direction and time. As a result there is a critical need to capture these variations via modeling and analysis. Zhu and Zhao provide an expert introduction to the techniques and analytical methods needed for studying underground excavations in fractured rock masses. The book brings together previously published and new material to provide a comprehensive and up-to-date reference. Provides practical solutions to the challenge of modeling and analyzing rock masses Consolidates a wealth of previously published technical papers on the subject and introduces previously unseen material

Stability of underground excavations is of great importance to an operating mine because it ensures the safety of the working people and operating equipment, and successful ore production. Due to the complex geological conditions and mine constructions, and variability and uncertainty in estimating rock mass mechanical properties, the assessment of rock mass stability for an underground mine is extremely challenging and difficult. Tackling of this difficult problem is not covered in detail in any of the textbooks currently available in the rock mechanics literature. This monograph aims to cover this gap in the rock mechanics and rock engineering field. This monograph provides detailed procedures for the stability assessment and support design for an underground mine case study. It covers the background of the mine site including the monitored deformation data, the state-of-art methodologies for the stability analysis of rock masses around underground excavations, performed laboratory tests, estimation of the rock mass properties, a brief theory and background of the 3-D Distinct Element Code (3DEC), and numerical modeling of underground rock mass stability including investigation of the effectiveness of rock supports. The monograph is an excellent reference for the senior undergraduates, graduate students, researchers and practitioners who work in the Underground Rock Mechanics and Rock Engineering area in the Mining Engineering, Civil Geotechnical Engineering and DEM (Distinct Element Method) Numerical modeling.

This new edition has been completely revised to reflect the notable innovations in mining engineering and the remarkable developments in the science of rock mechanics and the practice of rock angineering taht have taken place over the last two decades. Although "Rock Mechanics for Underground Mining" addresses many of the rock mechanics issues that arise in underground mining engineering, it is not a text exclusively for mining applications. Based on extensive professional research and teaching experience, this book will provide an authoratative and comprehensive text for final year undergraduates and commencing postgraduate stydents. For profesional practitioners, not only will it be of interests to mining and geological engineers, but also to civil engineers, structural mining geologists and geophysicists as a standard work for professional reference purposes.

The theme of the 31st US Symposium on Rock Mechanics is 'Rock Mechanics contributions and challenges', having as objective the examination and quantification of the progress that has been achieved in addressing the major practical challenges facing the science of rock mechanics and mine design. The 124 papers included in the proceedings cover areas such as: experimental studies (laboratory and field); conceptual, analytical, and numerical modeling; design and construction methods. 35 papers deal with practical mining problems and include information on rock reinforcement technology, blasting, rock bursts, open pit mining, remote sensing and borehole geophysics, mechanical fragmentation, and subsidence. Areas emphasized are coal and metal mine design problems. Other papers deal with the newest computer models, new instruments, fracture mechanics, new laboratory testing techniques, and in situ testing.

"Rock Engineering provides a comprehensive explanation of the geological principles and ground investigations involved with the geotechnical design and engineering of underground projects. It offers an internationally applicable, practical guide for engineers and geologists responsible for considering different ground conditions, design and planning for excavation and underground projects. This informative and highly illustrated resource combines theoretical knowledge and practical examples of rock engineering with detailed case studies of tunnelling and hydropower projects. Theories and realities of risks and uncertainties are discussed to provide an understanding of the considerations needed for successfully planning and executing underground projects. This fully updated edition has added focus on rock engineering applications in design, planning and excavation. Special chapters have been added dealing with the practical use of the Eurocode in rock design, the design principles of some special underground projects and three case histories. The ambition is to better cover the complex engineering geological process in rock construction, from ground investigation to execution"--Back cover.

Comprehensive Rock Engineering: Principles, Practice, & Projects, Volume 4: Excavation, Support, and Monitoring focuses on rock mechanics research and engineering, including excavation, drilling, blasting, and collapse mechanisms of boreholes. The selection first offers information on the construction process, mechanisms of rock fragmentation by blasting, and methods of improving blasting operations. Discussions focus on excavation, support, monitoring, stress wave mechanics, crater blasting, applications in construction and quarry blasting, fragmentation, damage, and environmental aspects. The text also ponders on the regulations, methods, and control techniques of blast monitoring and blast vibration monitoring for rock engineering. The publication takes a look at computer modeling and simulation of percussive drilling of rocks, mechanics of rock cutting, theoretical and practical rules for mechanical rock excavation, and use of water jets for rock excavation. Topics include drag pick cutting, excavating machines, adaptation of mechanical excavation to a harsh environment, abrasive water jets, and combined use of high pressure jets and mechanical cutting tools. The manuscript also examines design of support for underground excavations; development of tunnel support philosophy; and an overview of tunnel, underground excavation, and boreholes collapse mechanisms. The selection is a valuable reference for readers and rock engineering practitioners interested in pursuing research on rock engineering.

Rock Mechanics for Natural Resources and Infrastructure Development. Invited Lectures contains the Invited and Keynote Lectures and the prestigious ISRM Award Lectures (the Leopold Muller Award Lecture by professor Peter K. Kaiser and the Manuel Rocha Award Lecture by Dr. Quinghua Lei), as presented at the 14th ISRM International Congress (ISRM 2019, Foz do Iguaçu, Brazil, 13-19 September 2019). Starting in 1966 in Lisbon, Portugal, the International Society for Rock Mechanics and Rock Engineering (ISRM) holds its Congress every four years, where relevant themes related to rock mechanics and rock engineering are discussed. This volume covers topics ranging from fundamental research in rock mechanics, laboratory and experimental field studies, to petroleum, mining and civil engineering applications, and is a must-read for academics, engineers and students involved in rock mechanics and engineering. Proceedings in Earth and geosciences - Volume 5 The ‘Proceedings in Earth and geosciences’ series contains proceedings of peer-reviewed international conferences dealing in earth and geosciences. The main topics covered by the series include: geotechnical engineering, underground construction, mining, rock mechanics, soil mechanics and hydrogeology.

Rock Mechanics for Natural Resources and Infrastructure Development contains the proceedings of the 14th ISRM International Congress (ISRM 2019, Foz do Iguaçu, Brazil, 13-19 September 2019). Starting in 1966 in Lisbon, Portugal, the International Society for Rock Mechanics and Rock Engineering (ISRM) holds its Congress every four years. At this 14th occasion, the Congress brings together researchers, professors, engineers and students around contemporary themes relevant to rock mechanics and rock engineering. Rock Mechanics for Natural Resources and Infrastructure Development contains 7 Keynote Lectures and 449 papers in ten chapters, covering topics ranging from fundamental research in rock mechanics, laboratory and experimental field studies, and petroleum, mining and civil engineering applications. Also included are the prestigious ISRM Award Lectures, the Leopold Muller Award Lecture by professor Peter K. Kaiser. and the Manuel Rocha Award Lecture by Dr. Quinghua Lei. Rock Mechanics for Natural Resources and Infrastructure Development is a must-read for academics, engineers and students involved in rock mechanics and engineering. Proceedings in Earth and geosciences - Volume 6 The ‘Proceedings in Earth and geosciences’ series contains proceedings of peer-reviewed international conferences dealing in earth and geosciences. The main topics covered by the series include: geotechnical engineering, underground construction, mining, rock mechanics, soil mechanics and hydrogeology.

This classic handbook deals with the geotechnical problems of rock slope design. It has been written for the non-specialist mining or civil engineer, with worked examples, design charts, coverage of more detailed analytical methods, and of the collection and interpretation of geological and groundwater information and tests for the mechanical properties of rock.