• Home
  • Nick Ryland Barton
Nick Ryland Barton

Nick Ryland Barton
Nick Barton & Associates · Rock Engineering

PhD
Activity is often because wrong concepts have been used in rock cavern design, rock slope design. Must use discontinuum.

About

340
Publications
367,682
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
17,778
Citations
Citations since 2017
81 Research Items
8493 Citations
201720182019202020212022202302004006008001,0001,2001,400
201720182019202020212022202302004006008001,0001,2001,400
201720182019202020212022202302004006008001,0001,2001,400
201720182019202020212022202302004006008001,0001,2001,400
Introduction
International consultant: rock engineering, tunnelling, hydropower, metro, nuclear waste research, EDZ, fractured reservoirs. Non-linear rock joint behaviour, JRC, JCS, dilation, permeability, pre-grouting, jointed rock mass behaviour, non-linear shear strength criteria. Developer/co-developer of Q-system, Barton-Bandis M-H joint constitutive model, Q-tbm performance prognosis, Q-slope, Q-H2O. Invaluable interactions with Stavros Bandis, Khosrow Bakhtar, Axel Makurat, Panayiotis Chryssanthakis, Rajinder Bhasin, Karstein Monsen, Eystein Grimstad, Eda Quadros, Steinar Roald, Ricardo Abrahao, Baotang Shen, Neil Bar. scholar.google.com.br/citations?user=LcuOHRwAAAAJ&hl
Additional affiliations
April 2000 - March 2020
Nick Barton & Associates
Position
  • Managing Director
Description
  • International consultancy in rock engineering. Projects in a total of 40 countries from 1971 to present (2020)
January 1998 - December 2002
University of Sao Paulo's Polytechnic School
Position
  • Professor
Description
  • Autumn lecture course in rock mechanics and rock engineering
January 1985 - December 1989
Luleå University of Technology
Position
  • Professor
Description
  • Lectures in rock mechanics, once per week, two days in Luleå.
Education
September 1966 - December 1970
Imperial College London
Field of study
  • Rock Mechanics
September 1963 - June 1966
King's College London
Field of study
  • Civil Engineering

Publications

Publications (340)
Article
Full-text available
Construction of dams, tunnels and slopes in jointed, water-bearing rock causes complex interactions between joint deformation and effective stress. Joint deformation can take the form of normal closure, opening, shear and dilation. The resulting changes of aperture can cause as much as three orders of magnitude change in conductivity at moderate co...
Article
Full-text available
The feasibility of excavating caverns of very large span for underground siting of nuclear power stations in Norway was investigated in the early 1970s. In the end, the 1994 Winter Olympic Games provided the necessary impetus for utilizing a very large engineered rock cavern and proving its general feasibility. The 62m span Olympic Ice Hockey Caver...
Article
Full-text available
Engineering Classification of Rock Masses for the Design of Tunnel Support An analysis of some 200 tunnel case records has revealed a useful correlation between the amount and type of permanent support and the rock mass qualityQ, with respect to tunnel stability. The numerical value ofQ ranges from 0.001 (for exceptionally poor quality squeezing-gr...
Article
Full-text available
Rock joints exhibit a wide spectrum of shear strength under the low effective normal stress levels operating in most rock engineering problems. This is due to the Strong influence of surface roughness and variable rock strength. Conversely, under the high effective normal stress levels of interest to tectonophysicists the shear strength spectrum of...
Article
Full-text available
Simple, inexpensive index tests suitable for application to jointed core or jointed blocks of rock are described. These provide quantitative data on joint roughness, joint wall strength and residual friction angle, suitable for waste repository characterization. These three parameters form the basis of a new constitutive law of rock joint behavior...
Conference Paper
Full-text available
The NTNU and QTBM methods of prognosis are widely used for performance predictions and cost estimates in the planning and risk management of Tunnel Boring Machine (TBM) excavation projects. The methods have been applied for the evaluation of recently completed hard rock TBM projects, both during geological pre-investigations and prognosis and durin...
Conference Paper
Full-text available
Several decades ago there was a strong focus on the need for discontinuum modelling to improve upon the empirically based analysis of excavations in jointed rock. The remarkable codes developed by Peter Cundall: UDEC and 3DEC were put to full use in the nineteen eighties and nineties. For example, Q-system based cavern support could be verified or...
Article
Full-text available
Performance predictions and cost estimates are often decisive in the selection of excavation methods and have a major influence on the planning and risk management of Tunnel Boring Machine (TBM) excavation projects. A process of great complexity is involved during tunnel boring. When hard-to-very hard rock (i.e., low-to-extremely low boreability),...
Article
Full-text available
Fractures such as faults and joints often dominate the mechanical strength and deformation of rock masses. It is thus of central importance to adopt an appropriate joint constitutive model in geomechanics simulations so that the behaviour of fractures can be realistically represented. Over the past decades, various joint constitutive models have be...
Preprint
Full-text available
Dr Carranza-Torres has kindly pointed out an erroneous reference to a pit slope failure in Figure 47, p. 28 - which was a reproduction of his Eurock keynote Figure 1 of 2021. The planar failure surface was mistaken by NRB for the Bingham Canyon failure. Apologies. In fact earlier authors Lorig et al 2009 describe this failure as a wedge failure tha...
Preprint
Full-text available
Rock masses are by definition assemblies of rock blocks separated by joint sets and less frequent faults. Over the years quite accurate methods have been developed for numerical modelling of these assemblies, both in 2D (UDEC-MC, UDEC-BB) and in 3D (3DEC-MC). We have used them for studying how tunnels, caverns and slopes might perform when excavate...
Conference Paper
Full-text available
This paper was for a Workshop held in Madrid during 2006. The writer was not allowed to present this material. Very soon afterwards there was the tragic collapse of the Pinheiros station cavern, due to an unexplored ridge-of-rock despite five close-by boreholes, one in cavern centre. The paper emphasises the risk involved with too shallow metro pro...
Experiment Findings
Full-text available
Which is faster and more economic and less risk-enhancing: shallow or deeper siting of city road and metro? Two recent letters concerning a road project in Jerusalem and concerning the huge metro expansion in Moscow. Is it really cheaper 'to go shallow' with associated soil and saprolite stability problems, or is it cheaper and faster to go deeper?...
Conference Paper
Full-text available
Selected aspects of NMT are described in some detail. Tunnelling in jointed rock that may be clay-bearing and faulted is assumed, with a typical wide range of Q of at least 100 down to 0.01, or roughly RMR = 80 down to 20, but not needing double-shell NATM. Selected aspects to be discussed will be the three principle EDZ, two of them representing t...
Presentation
Full-text available
Strong opinions about GSI and H-B which match and extend some of the critical assessments in the literature. Continuum modelling may be mis-leading us too far along the road of a priori assumptions and black-box solutions. There was a move towards discontinuum methods 30-40 years ago, and we urgently need to return there after a twenty years deviat...
Presentation
Full-text available
The big dilemma: continuum with GSI and H-B or discontinuum with e.g. UDEC, UDEC-BB, 3DEC and taking longer time to produce something more realistic. Recent critique of GSI and attempts to quantify better are briefly reviewed. The extraordinary equations that produce the nice curves of shear strength are questioned, as one loses any sense of geolog...
Conference Paper
Full-text available
This paper deals with the exploration of failure modes in rock and rock masses. Failure in tension initially applies in deep tunnels, and extension failure also applies to cliffs and mountain walls. In each case a free surface is present. However, shear strength applies to the maximum mountain heights since confined compression strength is too high...
Presentation
Full-text available
Extension strain and failure in tension does a much better job in explaining and quantifying failure in tunnels, cliffs and mountain walls than Mohr-Coulomb shear strength components c and phi since intact rock has too high cohesion. M-C is good for rockfill and soil - presumably. In the case of the highest mountains, the critical state (maximum po...
Conference Paper
Full-text available
Development of the Q-system has meant engagement in water transfer tunnels, hydropower headrace and pressure tunnels in many countries since 1974. The support requirements of single-shell tunnels, were initially dominated by Norwegian and Swedish hydropower projects. The Q-system data base was greatly expanded later, by Grimstad's incorporation of...
Technical Report
Full-text available
For those interested in distinct element (jointed) models such as UDEC-BB and for input to 3DEC. A more interesting form of rock mechanics than continuum modelling - and more accurate too. Can be used for scoping coupled-behaviour with flow on the joints towards tunnels. Of course 2D limitations. But mechanisms of importance are illustrated - as pa...
Data
More extensive references to the use of the JRC-based criterion, going far beyond the 1977 'limit' of many referencing the method.
Experiment Findings
Full-text available
Details related to ‘the ten’ JRC profiles and further work with the Barton-Bandis criterion – why JRC, JCS and φr. Abstract-Introduction to numerous figures. This highly illustrated article, with minimal text, is basically an abstract followed by many figures and figure texts. It ends with a reference list that goes beyond Barton and Choubey, 197...
Method
Full-text available
For those who wish to work as an engineering geologist when logging core boxes or e.g. 5m lengths of tunnel advance (as opposed to guessing a GSI number - or 5 per core box, 5 per tunnel advance ??) then you can use the Q-histogram method that I have been using since 1987. It is much easier (faster) than trying to think of one representative Q-para...
Presentation
Full-text available
The four lectures have content DETAILED in the document. 1. THE MANY FACES OF Q 2. SHEAR STRENGTH of ROCK, ROCK JOINTS and ROCK MASSES: PROBLEMS and SOME SOLUTIONS 3. USING DEEP TUNNELS, CLIFFS, MOUNTAIN WALLS, MODELS AND MOUNTAINS: TO EXPLORE FAILURE MODES IN ROCK AND ROCK MASSES 4. TBM PERFORMANCE: CASE RECORD ANALYSIS including FAULTS, AND RECE...
Conference Paper
Full-text available
A brief glimpse of a forgotten period at rock mechanics conferences, when there was time for authors to be questioned, provide answers, and later have the discussions published as ‘Vol. 2’. The ‘Rock Fracture’ symposium of ISRM in Nancy, France in 1971 was the first for some of the freshly graduated Ph.D. students from Imperial College. Here there...
Conference Paper
Full-text available
The frequent assumption of those who feel they know best is that the Q-system only applies to typical hard jointed rocks. A prominent critic has even unilaterally suggested limiting the range of application of the Q-value to what he has assumed is likely to apply. The above were not the intention of the developer who did the interpretation of the o...
Chapter
Full-text available
This final chapter is designed to act as a cross-discipline reference point between rock mechanics and engineering geological behaviour in the ‘static’ world of slow-andmacro deformation processes, and the geophysicists ‘dynamic’ world of fast-and-micro deformation and attenuation processes. That there are important links between the two in terms o...
Conference Paper
Full-text available
An analysis of some 200 case records has revealed a useful correlation between the amount and type of permanent support and the rock mass quality Q, with respect to excavation stability. The rock mass quality Q is a function of six parameters,each of which has a rating of importance,which can be estimated from surface mapping and can be updated dur...
Conference Paper
Full-text available
This is the written question and answer Discussion of, in this case the Q-system paper by Barton, Lien and Lunde, 1977. The conference was held in Minnesota in 1975. Among others are discussions by Bieniawski, Bergman, Cundall, Franklin.
Conference Paper
Full-text available
This paper has not been on-line before. Barton, N., Lien, R. & Lunde, J. 1977. Estimation of support requirements for underground excavations. Proc. of 16th Symp. on Design Methods in Rock Mechanics, Minnesota, 1975. pp. 163-177. ASCE, NY. Discussion pp. 234-241. It is the first conference presentation of the Q-system, in 1975, with compendium from...
Conference Paper
Full-text available
Development of the Q-system has meant engagement in water transfer tunnels, hydropower headrace and pressure tunnels in many countries since 1974. The support requirements of single-shell tunnels, were initially dominated by Norwegian and Swedish hydropower projects. The Q-system data base was greatly expanded later, by Grimstad's incorporation of...
Negative Results
Full-text available
Negative results with a difference. A 2021 wish for a better year after the destruction of 1km of thin but beautiful sea ice representing 2D isotropy, converted by the adverse winds of 2020 into 10m of chaotic anisotropy and loss of life for those pieces discarded.
Conference Paper
Full-text available
This paper deals with the exploration of failure modes in rock and rock masses, starting with extension failure in deep tunnels, followed by analysis of the limited heights of cliffs, mountain walls and mountains. Here, tensile failure applies to the cliffs and mountain walls, since cohesive strength is too high, and shear strength applies to the m...
Conference Paper
Full-text available
3D physical model studies of excavated-under-stress tunnels or circular caverns are compared with 2D elasto-plastic solutions. Due presumably to the development of log-spiral shear surfaces, it is found that the estimated maximum stress in relation to the uniaxial compression strength is much higher than tolerated by hard brittle rocks prior to vio...
Experiment Findings
Full-text available
The TBM prognosis-method people have so far remained silent, so let me hazard a first response. As a briefest possible summary of past and published case-record-based opinions let us first consider that a project has a major portion that is too deep for borehole investigation, unless there is a mining company involved who are more-than-usually inte...
Data
The paper is a short resume of the author's experiences in various nuclear waste related research projects and actual planned repository characterization work. Several projects in the USA and several in Sweden, a major six-year study in the UK, and two volume reporting of the BB model in Canada. The work spanned 30 years, but if siting of nuclear p...
Conference Paper
Full-text available
Q-slope is an empirical rock slope engineering method for assessing the stability of excavated rock slopes in the field. Intended for use in reinforcement-free road or railway cuttings or in open cast mines, Q-slope allows rock engineers to make potential adjustments to slope angles as rock mass conditions become apparent during excavation. Q-slo...
Method
Full-text available
We read at intervals in excellent journals, or publish or lecture about what can go seriously wrong in our challenging underground media. It may be the occasional, easily explained, locally massive failures in single-shell tunnels, or the occasional, easily explained, locally massive failures in double-shell tunnels (or caverns under construction)....
Article
Full-text available
An observant Ph.D. student, Kieran Gilmore, from Cambridge University Earth Science Department was recently kind enough to inform the surviving author of the BB joint constitutive model (Stavros Bandis left us suddenly in 2014) that there was a ‘typo’ in the frequently RG referenced Bandis et al. 1983 paper. The errors concerned two negative signs....
Chapter
Failure of brittle rock is often associated with explicit fracturing events. Understanding fracturing behavior of rock masses has become a critical endeavour for not only civil engineering but also geological radioactive waste disposal, deep mining, geothermal energy extraction and CO2 geo-sequestration. Numerical simulations are vital tools for th...
Experiment Findings
Full-text available
Others did this first. Degrade c, mobilize phi. But for progressive failure understanding (always applies?) need four components: crack, crunch, scrape, swoosh: intact bridges fail, new fractures shear, capable joints shear, capable faults/clay-filled discontinuities shear - in a progressive manner.
Article
Full-text available
Single-shell tunnel design and execution, typical of NMT and Q-system based support design is contrasted with double-shell tunnel design and execution, typical of NATM. The particular advantages of fibre-reinforced shotcrete compared to mesh-reinforced or concrete final linings, in the case of drill-and-blast and Jn/Jr > 6 caused overbreak are emph...
Article
Full-text available
Rough joints can over-close due to a prior higher stress, or due to temperature increase alone. There is better fit of their opposing walls causing increased friction and even tensile strength. Well-controlled laboratory HTM tests, in situ HTM block tests, and large-scale heated rock mass tests, lasting several years at Stripa, Climax and Yucca Mou...
Chapter
Full-text available
King, 2005 recently summed up the major exploration-related goals of rock physics research. They are 'to understand how lithology, porosity, confining stress and pore pressure, pore fluid type and saturation, anisotropy and degree of fracturing, temperature, and frequency influence the velocities and attenuation of compressional P-and S-waves in se...
Presentation
Full-text available
1. INTRODUCTION TO Q-PARAMETERS, CORE LOGGING, UNEXPECTED ERROR IN A GEOLOGIC INVESTIGATION 2. NMT – NATM CONTRASTED, SHOTCRETE, BOLTS, RRS, LATTICE GIRDERS, OVER-BREAK AND CONSEQUENCES 3. TUNNEL AND CAVERN DEFORMATION, RELATIVE COST AND TIME 4. SEISMIC VELOCITY, DEFORMATION MODULUS, DEPTH 5. LIMITATIONS OF SHEAR STRENGTH MODELS, MODELLING 6....
Chapter
Full-text available
The Q-system for rockmass, core and tunnel logging was used extensively in the TransManche Link TBM tunnelling, and also in a consortium claim against owner Eurotunnel in the early 1990s. In this connection, the Q-system was also used by the first author for logging precedent conditions in local tunnels in chalk marl, and by the construction consor...
Chapter
Full-text available
The term ‘characterisation’ will be used to describe methods of collection and interpretation of the physical attributes of the joints and other discontinuities, in other words those which control their mechanical and hydraulic properties, and the behaviour of jointed rock as an engineering medium. Rock discontinuities vary widely in terms of their...
Conference Paper
The apparent 8 to 9km height limit of mountains will be addressed using critical state shear strength arguments, since confined compression strength is too high to explain these 'limited' heights. Modified Mohr Coulomb criteria have been derived based on critical state mechanics for rocks. These criteria are utilised to obtain estimates of maximum...
Technical Report
Full-text available
The Q-system for rockmass, core and tunnel logging was used extensively in the TransManche Link TBM tunneling, and also in a consortium claim against owner Eurotunnel in the early 1990's. In this connection, the Q-system was also used by the first author for logging precedent conditions in local tunnels in chalk marl, and by the construction consor...
Presentation
Full-text available
The Q-slope method for rock slope engineering was developed to allow engineering geologists and rock engineers to rapidly assess the stability of excavated rock slopes in the field, and make optimal adjustments to slope angles as rock mass conditions become apparent during the construction of road cuts or benches. An empirical relationship between...
Conference Paper
Full-text available
The Q-slope method for rock slope engineering was developed to allow engineering geologists and rock engineers to rapidly assess the stability of excavated rock slopes in the field, and make optimal adjustments to slope angles as rock mass conditions become apparent during the construction of road cuts or benches. An empirical relationship between...
Presentation
Full-text available
The strength of rock and rock masses is poorly represented by Mohr-Coulomb. Adding cohesive and frictional components is not consistent with reality. Failure may initiate and propagate via the overcoming of up to four strength components, perhaps five if we add block-rotation mechanisms. When the rock is more massive, or is with no 'capable' joint...
Conference Paper
Full-text available
In relation to soil, rock is usually extremely strong, with a compression strength that will seldom be mobilized, even in deep tunnels. Intact rock may also have cohesion that is so high that it makes mountain avalanches rare events. Frictional strength tends to be high as well, due to the big contribution of dilation unless the rock has high poros...
Article
Full-text available
Pre-grouting ahead of tunnels has three main functions: to control inflow into the tunnel, to limit groundwater drawdown above the tunnel, to make tunnelling progress more predictable since rock mass quality is effectively improved. It helps to avoid settlement damage caused by consolidation of clay deposits beneath built up areas, since towns tend...
Article
Full-text available
Pre-grouting ahead of tunnels has three main functions: to control water inflow into the tunnel, to limit groundwater drawdown above the tunnel, and to make tunnelling progress more predictable since rock mass quality is effectively improved. It helps to avoid settlement damage caused by consolidation of clay deposits beneath built-up areas, since...
Article
Full-text available
The Q-slope method for rock slope engineering provides an empirical means of assessing the stability of excavated rock slopes in the field. Q-slope allows geotechnical engineers and engineering geologists to make potential adjustments to slope angles as rock mass conditions become apparent during the construction of reinforcement-free road or railw...
Article
Full-text available
Brittle rock can fail in tension even when all principal stresses are compressive. The culprit is Poisson’s ratio, but marked stress anisotropy due to a neighbouring free surface, and due to a raised principal tangential stress is also necessary. Extension strain-induced failure causes fracture initiation in tension. Propagation in unstable shear m...
Presentation
Full-text available
An invited lecture with illustrated examples of ambient and thermal over-closure of rough fractures and joints respectively. Well-documented cases from nuclear-waste related in situ tests mostly in the USA and in Sweden are illustrated. If rougher joints remain thermally over-closed, and have higher shear strength, stiffness etc. there is a possibi...
Conference Paper
Full-text available
Rougher joints may remain over-closed when subjected to a higher normal stress than that used during shear testing. They have higher shear strength, normal stiffness etc. Rougher joints that are simply heated may also thermally over-close and have numerous enhanced properties including smaller aperture, lower permeability, higher stiffness, strengt...
Conference Paper
Full-text available
Intact brittle rock can fail in tension even when all principal stresses are compressive. This is due to lateral expansion and extension strain when near to a free surface, caused by Poisson's ratio. Exceeding tensile strength due to stress anisotropy and Poisson's ratio are the fracture-initiating conditions around deep tunnels, not the increasing...
Article
Full-text available
This paper investigates the mechanisms of tunnel spalling and massive tunnel failures using fracture mechanics principles. The study starts with examining the fracture propagation due to tensile and shear failure mechanisms. It was found that, fundamentally, in rock masses with high compressive stresses, tensile fracture propagation is often a stab...
Presentation
Full-text available
Fracturing initiation in deep tunnels is linked to extension strain and exceedence of tensile strength, with the help of Poisson's ratio and a nearby free surface, not '0.4 x UCS'. The critical heights of cliffs in rock, and the highest mountain walls cannot be predicted with c and phi based soil mechanics: even the lower bound 2c/gamma x tan( 45+...
Presentation
Full-text available
The Q-slope method for rock slope engineering and its integration with the use of geophysical survey data. The presentation covers the theory and several case studies on the application of the Q-slope method; the original Q-system and Q-slope correlations with Vp (p-wave velocity) obtained from geophysical surveys.
Data
Linking extension strain failure in tension in deep tunnels, with height limits for cliffs in weak rocks like tuff, and high mountain walls in strong rocks like granite. Height limits for the highest mountains is critical state shear strength limited. Uniaxial strength seems to give 'the right result' (about 9km) but for the wrong reasons.
Article
Full-text available
The Q-slope method for rock slope engineering provides an empirical means of assessing the stability of excavated rock slopes in the field. It enables rock engineers and engineering geologists to make potential adjustments to slope angles as rock mass conditions become apparent during the construction of reinforcement-free road or railway cuttings...
Presentation
Full-text available
A keynote lecture at Eurock's St. Petersburg Youth Forum Event. Using the common language of Q-histogram descriptions where convenient, the lecture covered early physical modelling of large caverns, carried out (with 20,000 block models) prior to UDEC release in 1977-78. These were principally for 50m span reactor-vessel caverns for underground nuc...
Article
Full-text available
In this paper, the Mohr-Coulomb shear strength criterion is modified by mobilising the cohesion and internal friction angle with normal stress, in order to capture the nonlinearity and critical state concept for intact rocks reported in the literature. The mathematical expression for the strength is the same as the classical form, but the terms of...
Conference Paper
Full-text available
It is common knowledge that TBM are remarkable machines. It nevertheless takes mental effort to accept that they can have world record 1 day, 1 week and 1 month tunnel advance as high as 172m, 703m and 2163m. However, the best monthly project averages for the usually smaller 3m to 6m diameter machines which have delivered these incredible records a...
Article
Full-text available
For many decades, a tunnelling method has been in use which effectively minimizes the use of concrete, which should be one of the goals in our CO2-producing planet. We call the method NMT (Norwegian Method of Tunnelling) and emphasize its ‘single-shell’ characteristics, to distinguish it clearly from double-shell NATM (the so-called New Austrian Tu...
Article
Full-text available
Q-slope is an empirical rock slope engineering method for assessing the stability of excavated rock slopes in the field. Intended for use in reinforcement-free road or railway cuttings or in opencast mines, Q-slope allows geotechnical engineers to make potential adjustments to slope angles as rock mass conditions become apparent during construction...
Conference Paper
Full-text available
Large tunnel and rock cavern spans that have failed for 'geological' reasons, or because of design errors, are the main focus of this presentation. The effect of adverse and sometimes unexplored geology will be illustrated. We will need to recognize that pre-investigations might miss some important detail, despite an exceptional frequency of core d...
Technical Report
Full-text available
Intact brittle rock can fail in tension even when all principal stresses are compressive. This is due to lateral expansion and extension strain when near to a free surface, caused by Poisson's ratio. Tensile strength and Poisson's ratio are the fracture-initiating parameters around deep tunnels, not the increasing mobilization of compressive streng...
Article
Full-text available
Experiments on rock joint behaviors have shown that joint surface roughness is mobilized under shearing, inducing dilation and resulting in nonlinear joint shear strength and shear stress vs. shear displacement behaviors. The Barton-Bandis (B-B) joint model provides the most realistic prediction for the nonlinear shear behavior of rock joints. The...
Presentation
Full-text available
Co-author Baotang Shen discovered the actual reason for tunnels in hard rocks starting to ’stress’ fracture when reaching ’0.4 x UCS’. This critical tangential stress is explaind as extension strain-induced fracturing involving tensile strength and Poisson’s ratio. This new insight is utilized in critical cliff and mountain wall height estimates, u...
Conference Paper
Full-text available
Brittle rock can fail due to extension strain over-coming the tensile limit, even when all stresses are compressive. Two related topics can thereby be addressed. The first is extension strain-induced failure in deep tunnels and mines, with fracture initiation in tension but subsequent propagation in shear. The familiar ratio of maximum tangential s...
Conference Paper
Full-text available
Rock masses obviously represent the most variable of engineering materials, and the three categories listed in the title represent most of the range of rock quality. We need to include stress magnitudes, water pressure and permeability to be more complete, but will ignore swelling pressures. This keynote paper will address some new findings about t...
Article
Full-text available
Det er ikke mange som vil trekke 'likhetstegn' mellom bergbrudd i tunneller dvs. den lydgivende og noen ganger livsfarlig 'bergslag', og de alltid begrenset høyder av sjøkystens klipper og fjellsiders vertikale vegger. Høydevariasjon her kan vaere så lite som 10-15m i svak fjell f. eks. sandstein eller vulkanske tuff, til de sjelden 1,000-1,200m hø...