PDF | 10 minutes read | Fundamentals of Rock Mechanics, 4th edition. Table of Contents. 1. Rock as a Material. 2. Analysis of Stress and Strain. mechanics: part 2. I I lustrative worked Lecturer in Engineering Rock Mechanics at Imperial Engin. This book covers the fundamentals of structural mechanics. Fundamentals of Rock Mechanics. Fourth Edition. J. C. Jaeger, N. G. W. Cook, and R. W. Zimmerman. Blackwell. Publishing. CONFIDENTIAL. BP-HZN-.

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Fundamentals of. Rock Mechanics. J. C. Jaeger. Professar of Geophysics in the. Australian National University. N. G. W. Cook. Director of the Mining Research. Fundamentals of rock mechanics – J.C. Jaeger, N.G.W. Cook, and R.W. Zimmerman. – 4th ed. p. cm. Includes bibliographical references and. Widely regarded as the most authoritative and comprehensive book inits field, the fourth edition of Fundamentals of RockMechanics includes new and.

Table of geological formations and earth history Appendix 4: Some petrographic properties of rocks Author Index Index of geographical names, dam sites, reservoirs, tunnels and caverns Subject Index Preface At the time the first edition of Rock Mechanics and Engineering was being printed, important progress was being made both in theory and practice of rock mechanics.

Some new advances were analysed in an 'Appendix' to the book, which is now incorporated, with the necessary additions, in the relevant chapters of the second edition.

New developments of the new Austrian tunnelling method NATM and similar methods caused the important chapter on underground power-stations to be rewritten, and several new chapters to be added.

The problem of bridging the gap between scientific research in rock mechanics and practical engineering has become more acute. Such bridging has recently been achieved in Fluid Transients Jaeger ; it is also vital to applied rock mechanics, as explained in the Preface to the first edition.

Many geologists suggest that the rock quality designation RQD of Deere is the most reliable parameter for an engineering classification of jointed rock masses. Some geophysicists did not agree and recently introduced their own more complex classification, based on the combination of several parameters describing rock characteristics. Engineers in charge of the construction of large tunnels and underground works were not convinced by these efforts and base their own designs on the rock deformations they expect to occur.

The second edition deals with these problems in several new chapters. There is no better method to deal with them than the close analysis of some case histories. The discussion on the engineering classification of jointed rock masses and the required rock support is illustrated by the description of the second Gotthard Tunnel 16 km long , now under construction and the design of the third, so-called Basis, Tunnel 40 km long.

Many other points require illustration by case histories and two new chapters are introduced. One concerns the stability or instability of rock faces and possible rock slides chapter The work done for the m high, very steep, rock abutment of Tachien Dam is one of the situations analysed.

Underground works is the second subject chosen for extensive new developments chapter Comparing all the case histories on dam foundations, slope stability, rock slides, underground works developed in this second edition brings an answer [ix] x Preface to the many attempts at classifying jointed rock masses for engineering purposes.

There is no universal rule or classification to solve problems of applied rock mechanics. Any one problem is to be examined in its many aspects from first principles, using all information available from geology, geophysics, rock hydrology and engineering. I should like to express my thanks to Professor F. Beavis who painstakingly read through my revisions, suggesting a number of corrections and several most helpful emendations.

Fully, July Preface to the first edition The first attempts at investigating the mechanical and physical properties of rocks go back to the second half of the last century; but systematic efforts to develop this into a real science of rocks are recent.

One of the more important results of these efforts has been to show the paramount importance of voids, fissures and faults at the level of rock crystals or grains of the rock material and of large masses of rocks in situ. Any theory of rock mechanics which considers rocks to be no more than homogeneous masses is just a first approximation. All the properties of rock and rock constants: strength, elasticity, plasticity, perviousness and reactions to sound and to seismic waves depend on the gaps, voids or fissures of the rock as much as on the skeleton of the solid material which builds it up.

It is from this point of view that this book has been written. One of the main purposes of the book is to stress the many links between rock mechanics and engineering.

Deb D., Verma A.K. Fundamentals and Applications of Rock Mechanics

Mining engineers and civil engineers cannot excavate mines or build structures without a knowledge of rock mechanics. This is now accepted by these professions, which include discussions on rock mechanics at their international congresses and symposia. On the other hand, the benefit that rock mechanics gets from the development of modern engineering techniques has seldom been adequately appreciated. Mining engineering was active at the start of engineering geology and, some decades later, at the birth of the new science of rock mechanics— different from both engineering geology and petrography.

It is less well known how great an impulse rock mechanics got from progress and research in civil engineering. Among civil engineers, dam designers were the first to become interested in the progress of rock mechanics. They soon realized that rock foundations were part of the design of any dam. They developed their own techniques for measuring the strength and elasticity of rock masses: in situ, at the rock surface, in trenches and in galleries.

They recognized the paramount importance of the joints,fissuresand faults in the rock masses and contributed to the development of methods for tridimensional representation of families of fissures, testing their shear strength and curing them. The latest tendency of dam designers is to direct their efforts towards a more precise description of the type of rupture occurring at different depths inside the rock masses, and an estimate of the static and dynamic effect of water seeping through the joints andfissures.

New chapters of rock mechanics were opened by the joint efforts of dam designers and rock specialists. More recently, vibrations of the earth's crust and earthquakes were analysed by them. For many years, tunnel designers worked from empirical rules.

At the beginning of the century interest in the strength, elastic and plastic properties of rocks arose. The notion of stress and strain patterns developing about empty galleries or caverns, or around pressure tunnels, is more recent: the sudden undertaking, for many purposes, of large underground works, forced specialists to consider new methods of stress and strain analysis.

The finite element method allows the analysis of jointed rock masses, crossed by fissures or faults. More recently still, the effects of rock relaxation about cavities and the drop of the modulus of deformation in relaxed rock were analysed. These entirely new concepts about the behaviour of rock masses are initiating new lines of research in rock mechanics. And progress in engineering is linked with active research in rock mechanics. Part one of the book chapters 1 and 2 stresses the importance of the geologist's work, without which the science of rocks would not exist.

Part two chapters 3 to 8 co-ordinates the knowledge of the physical and mechanical properties of rock acquired from the ample information submitted to the First and Second Congresses and the Sixth Symposium on Rock Mechanics. Chapters 3 to 4 deal with the rock material—laboratory samples— with no major fractures, and chapters 5 to 8 study the properties and behaviour of rock masses in situ, and analyse strains and stresses in such masses.

Abstract knowledge of rock properties is of limited use to engineers.

It is vital to bridge the gap between the accumulated scientific data on rocks and the requirements of design and field engineers. The second half of the book deals with practical applications. Part three analyses the diverse aspects of rock slope stability chapter 9 and the strains about cavities excavated in the rock and the modern techniques of underground works chapter Chapter 11 discusses the very controversial problem of dam rock abutment design.

Part four chapters 12 to 14 describes typical case histories, which illustrates the more important points developed in parts two and three. Pulfy, March Part One Introduction to rock mechanics 1 The historical development of rock mechanics 1. Mining engineers and tunnel experts watching rock bursts and rock squeezing in tunnels and galleries, suggested that some 'residual forces' were still at work in rock at great depth. The German tunnel expert Rziha was probably the first to be concerned with the horizontal component of the forces acting in many tunnels.

A few years later Heim Professor at Zurich University and at Zurich Federal Institute of Technology suggested that the horizontal force component must be of the same order of magnitude as the vertical component and he forcefully stressed this opinion in several papers It took many decades for geologists and engineers to realize the importance of the ideas of Heim and Rziha. In , the Ritom tunnel, which had just been built south of the Alps by the Swiss Federal Railways, was severely damaged.

Inspection showed many longitudinal fissures running along the tunnel. The rock strata had a general dip towards the valley and it was feared that water seepage could cause a rock slide. The tunnel was repaired. They decided to start pressure tests in this second tunnel. A dead end of the gallery was sealed off with a concrete plug provided with a manhole and steel cover and wasfilledwith water under pressure.

The tunnel diameters were measured by a spider with six branches and the length variations of the six radii versus time were recorded on a rotating disc. The varying water pressure was also recorded and strain-pressure diagrams traced. The bulk modulus of elasticity was estimated as a ratio of stress versus deformation.

This was probably the first recording of the elastic deformations of rock masses. A few years later J. Schmidt a, b published a thesis in which he [1] 2 Historical development of rock mechanics cleverly combined Heim's ideas about residual stresses in rock, with the newly formulated ideas of rock elasticity to produce the first attempt at a theory of rock mechanics. It was at this time that steel linings for tunnels and shafts were first introduced, and several authors Jaeger, , in different countries, produced papers estimating the stresses in the lining as a function of the relative elasticity of the steel and the rock.

It is a truly interdisciplinary subject, with applications in geology and geophysics, mining, petroleum and geotechnical engineering. Rock engineering is concerned with specific engineering circumstances, for example, how much load will the rock support and whether reinforcement is necessary. As a solid material, rock is often: In the context of the mechanics problem, we should consider the material and the forces applied to it.

We have the intact rock which is itself divided by discontinuities to form the rock structure. We find then the rock is already subjected to an in situ stress.

In all of these subjects, the geological history has played its part, altering the rock and the applied forces. From this curve, several features of interest are derived: The overall geometrical configuration of the discontinuities in the rock mass is termed rock structure. It is often helpful to understand the way in which discontinuities form.

There are three ways in which a fracture can be formed: Some examples of the way in which the discontinuity genesis leads to differing mechanical properties are: In some cases, such as a dam or nuclear power station foundation, the load is applied to this. In other cases, such as the excavation of a mine or tunnel, no new loads are applied but the pre- existing stresses are redistributed.

Thus the study of flow in rock masses will generally be a function of the discontinuities, their connectivity and the hydrogeological environment. Other aspects, such as groundwater chemistry and the alteration of rock and fracture surfaces by fluid movement may also be of concern. Thus we have two types of behaviour: Both mathematical and engineering mistakes are easily made if this crucial difference is not recognized and understood.

Fundamentals of Rock Mechanics

These forces create the stress tensor. The normal and shear stress components are the normal and shear forces per unit area.

It should be remembered that a solid can sustain a shear force, whereas a liquid or gas cannot. A liquid or gas contains a pressure, which acts equally in all directions and hence is a scalar quantity.

In fact, the strict definition of a second-order tensor is a quantity that obeys certain transformation laws as the planes in question are rotated.

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F1, F2, …, Fn. Consider now the forces that are required to act in order to maintain equilibrium on a small area of a surface created by cutting through the rock. Although there are practical limitations in reducing the size of the area to zero, it is important to realize that the stress components are defined in this way as mathematical quantities, with the result that stress is a point property. Note that the force and displacement have been scaled respectively to stress by dividing by the original cross-sectional area of the specimen and to strain by dividing by the original length.

It is important to realize that the compressive strength is not an intrinsic property. Intrinsic material properties do not depend on the specimen geometry or the loading conditions used in the test: These features are crucial in the design and analysis of underground excavations. If the ratio of sample length to diameter is kept constant, both compressive strength and brittleness are reduced for larger samples.

Rock specimens contain microcracks: In other words, rock has strength in tension, compression and shear. Brazilian tensile test, triaxial compression test, etc. Most rocks are therefore strengthened by the addition of a confining stress. As the confining pressure is increased, the rapid decline in load carrying capacity after the peak load is reached becomes less striking until, after a mean pressure known as the brittle-to-ductile transition pressure, the rock behaves in a near plastic manner.

In most cases, however, it is the effect of pore water pressure that exerts the greatest influence on rock strength. If drainage is impeded during loading, the pores or fissures will compress the contained water, raising its pressure.

Through these processes, four primary time-dependent effects can be resolved: Creep — strain continues when the applied stress is held constant. Relaxation — a decrease in strain occurs when the applied stress is held constant.

Fatigue — an increase in strain occurs due to cyclic changes in stress. The limited test data does show though, that increasing temperatures reduces the elastic modulus and compressive strength, whilst increasing the ductility in the post-peak region.

Building on the history of material testing, it was natural to express the strength of a material in terms of the stress present in the test specimen at failure i. Since uniaxial and triaxial testing of rock are by far the most common laboratory procedures, the most obvious means of expressing a failure criterion is: In two-dimensions, this is expressed as: However, some limitations are: A tension cutoff has been introduced to the Mohr-Coulomb criterion to predict the proper orientation of the failure plane in tension.

They can be considered linear only over limited ranges of confining pressures. Despite these difficulties, the Mohr-Coulomb failure criterion remains one of the most commonly applied failure criterion, and is especially significant and valid for discontinuities and discontinuous rock masses. Since this is one of the few techniques available for estimating in situ rock mass strength from geological data, the criterion has become widely used in rock mechanics analysis.

Discontinuities have been introduced into the rock by geological events, at different times and as a result of different stress states.One concerns the stability or instability of rock faces and possible rock slides chapter These forces create the stress tensor. Most rocks are therefore strengthened by the addition of a confining stress. Important research had been going on on both sides of the Atlantic mainly in connection with the mining industry. It is often useful to present this data in a graphical form to aid visualization and engineering analysis.

It is least for indurated sandstone and indurated shales; normally cemented specimens have a lower i index than poorly cemented and poorly compacted specimens. Part one of the book chapters 1 and 2 stresses the importance of the geologist's work, without which the science of rocks would not exist.

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