Abstract
Anisotropy is everywhere. Isotropy is rare. Round stones are collectors’ items, and any almost cubic blocks are photographed, as they are the exception. The reasons for rock masses to frequently exhibit impressive degrees of anisotropy, with properties varying with direction of observation and measurement, are clearly their varied geological origins. Origins may provide distinctive bedding cycles in sedimentary rocks, distinctive flows and flow-tops in basalts, foliation in gneisses, schistosity in schists and cleavage in slates, and faults through all the above. We can add igneous dykes, sills, weathered horizons, and dominant joint sets. Each of the above are rich potential or inevitable sources of velocity, modulus, strength and permeability anisotropy—and inhomogeneity. The historic and present-day stress anisotropy provides a wealth of effects concerning the preferentially oriented jointing, with its reduced roughness and greater continuity. High stress may also have induced oriented micro-cracks. All the above reinforce disbelief in the elastic-isotropic-continuum or intact-medium-based assumptions promoted by commercial software companies and used by so many for modelling rock masses. RQD and Q are frequently anisotropic as well, and Q is anisotropic not just because of RQD. The authors, therefore, question whether the a priori assumption of homogeneous-isotropic-elastic behaviour has any significant place in the scientific practice of realistic rock mechanics.
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Abbreviations
- BB:
-
Barton-Bandis constitutive model for rock joints
- E mass :
-
Static modulus of deformation
- E :
-
Average physical aperture of a joint
- e :
-
Hydraulic aperture of a joint
- EDZ:
-
Excavation disturbed zone
- J a :
-
Rating for joint alteration, discontinuity filling
- JCS:
-
Joint wall compression strength
- J n :
-
Rating for number of joint sets
- J r :
-
Rating for joint surface roughness
- JRC:
-
Joint roughness coefficient
- J w :
-
Rating for water softening, inflow and pressure effects
- K :
-
Permeability (units m/s)
- K n :
-
Normal stiffness of a joint
- K s :
-
Shear stiffness of a joint
- K int :
-
Intermediate principal permeability
- K max :
-
Maximum principal permeability
- K min :
-
Minimum principal permeability
- k o :
-
Ratio of σ h/σ v
- NGI:
-
Norwegian Geotechnical Institute
- Q :
-
Rock mass quality rating (range 10−3 to 103)
- Q c :
-
Rock mass quality rating (Q, or Q o normalized by σ c/100)
- Q o :
-
Q calculated with RQDo oriented in the loading or measurement direction
- Q seis :
-
Seismic quality factor—the inverse of attenuation (used by geophysicists, normally with the P- and S-wave components ‘Q p’ and ‘Q s’)
- RQD:
-
Rock quality designation (% of core-pieces ≥10 cm in length)
- RQDo :
-
RQD oriented in the loading or measurement direction (in the QTBM model it is in the tunnelling direction)
- σ c :
-
Uniaxial strength
- σ v :
-
Vertical (principal) stress
- σ h :
-
Horizontal (principal) stress
- σ θ :
-
Tangential stress (surrounding an excavation, borehole)
- UDEC:
-
Universal distinct element code, for modelling a two-dimensional, 1 m thick slice of the rock mass
- V p :
-
P-wave seismic velocity (km/s)
- V s :
-
S-wave seismic velocity (km/s)
References
Addis MA, Barton N, Bandis SC, Henry JP (1990) Laboratory studies on the stability of vertical and deviated boreholes. In: 65th Annual Technical Conference and Exhibition of the Society of Petroleum Engineers, New Orleans, September 23–26, 1990
Bandis S, Lumsden A, Barton N (1981) Experimental studies of scale effects on the shear behaviour of rock joints. Int J Rock Mech Min Sci Geomech Abstr 18:1–21
Bandis S, Lumsden AC, Barton N (1983) Fundamentals of rock joint deformation. Int J Rock Mech Min Sci Geomech Abstr 20:249–268
Barkved O, Bartman B, Gaiser J, Van Dok R, Johns T, Kristiansen P, Probert T, Thompson M (2004) The many facets of multicomponent seismic data. Oilfield Rev, Summer 2004, Schlumberger, pp 42–56
Barton N (1973) Review of a new shear strength criterion for rock joints, engineering geology, vol 7. Elsevier, Amsterdam, pp 287–332
Barton N, Choubey V (1977) The shear strength of rock joints in theory and practice. Rock Mechanics 10:1–54
Barton N (1981) Hydraulic fracturing to estimate minimum stress and rockmass stability at a pumped hydro project. In: Proceedings of Work-shop on Hydraulic Fracturing Stress Measurements, Monterey, USA
Barton N (1986) Deformation phenomena in jointed rock. 8th Laurits Bjerrum Memorial Lecture, Oslo. Geotechnique 36(2):147–167
Barton N (1994) A Q-system case record of cavern design in faulted rock. In: 5th International Rock Mechanics and Rock Engineering Conference, Tunnelling in difficult conditions, Torino, Italy, pp 16.1–16.14
Barton N (2000) TBM tunnelling in jointed and faulted rock. Balkema, Rotterdam, p 173
Barton N (2006) Rock quality, seismic velocity, attenuation and anisotropy. Taylor & Francis, UK & Netherlands, p 729
Barton N (2010) Low stress and high stress phenomena in basalt flows. Keynote paper. In: 3rd International Workshop on Rock Mechanics and Geo-Engineering in Volcanic Environments, Tenerife
Barton N, Grimstad E (1994) The Q-system following twenty years of application in NMT support selection. 43rd Geomechanic Colloquy, Salzburg. Felsbau 6(94):428–436
Barton N, Infanti N (2004) Unexpected stress problems in shallow basalts at the Ita hydroelectric power project in S.E. Brazil. In: Proceedings ARMS 2004: 3rd Asian Rock Mechanics Symposium, Kyoto
Barton N, Makurat A, Hårvik L, Vik G, Bandis S, Christianson M, Addis A (1988) The discontinuum approach to compaction and subsidence modelling as applied to Ekofisk. In: BOSS ‘88. Proceedings of International Conference on Behaviour of Offshore Structures, Trondheim, vol 1, pp 129–141
Duellmann H, Heitfeld KH (1978) Influence of grain fabric anisotropy on the elastic properties of rocks. In: Proceedings 3rd IAEG Congress, Madrid, II(1), Imprime ADOSA, Madrid, pp 150–162
Heffer K (2002) Geomechanical influences in water injection projects: an overview. Oil Gas Sci Tech Rev IFP 57(5):415–422
Hesler GJ, Cook NGW, Myer L (1996) Estimation of intrinsic and effective elastic properties of cracked media from seismic testing. In: Aubertin, Hassani, Mitri (eds) 2nd NARMS’96. Montréal, Québec, Balkema, Rotterdam, pp 467–473
Horne S (2003) Fracture characterization from walkaround VSPs. Geophys Prospect 51:493–499
King MS, Myer LR, Rezowalli JJ (1984) Cross-hole acoustic measurements in basalt. In: Dowding, Singh (eds) 25th US symposium on rock mechanics, Evanston, IL. Society of Mining Engineers, New York, pp 1053–1061
Leary PC, Henyey TL (1985) Anisotropy and fracture zones about a geothermal well from P-wave velocity profiles. Geophysics 50(1):25–36
Martin DC, Christiansson R, Soderhall J (2001) Rock stability considerations for siting and constructing a KBS-3 repository, based on experience from Äspö HRL, AECL’s HRL, tunnelling and mining. SKB (Swedish Nuclear Fuel Co.) Stockholm, TR-01-38
Nur A (1971) Effects of stress on velocity anisotropy in rocks with cracks. J Geoph Res 76(8):2022–2034
Oberti G, Carabelli E, Goffi L, Rossi PP (1979) Study of an orthotropic rock mass: experimental techniques, comparative analysis of results. In: Proceedings of 4th ISRM Congress, Montreux, vol 2. Balkema, Rotterdam, pp 485–491
Quadros E, Abrahão R (2002) Percolation and grouting in basaltic rocks—some Brazilian experience. In: Proceedings of the ISRM International Symposium on Rock Mechanics, EUROCK´ 2002—Workshop on Volcanic Rocks, vol 1. SPG, Madeira, Portugal, pp 125–135
Quadros E, Correa Filho D (1993) Scale effects on the hydraulic properties determined by in situ 3-D tests. In: ISRM International Symposium on Rock Mechanics, EUROCK´ 93—scale effects in rock masses, Lisbon, vol 1. Balkema, Rotterdam, pp 313–321
Quadros E, Correa Filho D (1998) Analysis of grouting efficiency and deformations using three-dimensional hydraulic tests. In: Vth South American Rock Mech Cong., ISRM Regional Symposium SAROCK´S 98, Brazil, vol 1. Politécnica, EDUSP, pp 515–523
Quadros E, Correa Filho D (1999) 3-D hydraulic tests for the subway of São Paulo, Brazil. In: Proceedings of 9th ISRM Congress on Rock Mechanics, Paris, vol 2. Balkema, Rotterdam, pp 817–823
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Barton, N., Quadros, E. Anisotropy is Everywhere, to See, to Measure, and to Model. Rock Mech Rock Eng 48, 1323–1339 (2015). https://doi.org/10.1007/s00603-014-0632-7
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DOI: https://doi.org/10.1007/s00603-014-0632-7