Dight, PM & Dyskin, AV 2008, 'On the Determination of Rock Anisotropy for Stress Measurements', in Y Potvin, J Carter, A Dyskin & R Jeffrey (eds), SHIRMS 2008: Proceedings of the First Southern Hemisphere International Rock Mechanics Symposium
, Australian Centre for Geomechanics, Perth, pp. 575-585, https://doi.org/10.36487/ACG_repo/808_180
The traditional methods of in situ stress determination can be seriously affected by rock anisotropy, which necessitates both development of the corresponding interpretation methods and accurate determination of the elastic characteristics of the anisotropic rocks. In this contribution we consider the method of determination of anisotropic moduli by testing small subcores drilled in different directions. Rock anisotropy is often induced by the presence of joints, foliation, schistosity, bedding or similar features. In the case when the spacing between the theses features exceeds the length of the subcores the results of moduli determination in separate subcores shows considerable variability. A mechanism of this variability lies in the fact that a particular subcore may or may not be intersected by a joint. We show that despite this, the averaging procedure used in the method of moduli reconstruction, developed previously by the authors, can still be successfully applied, since the averaging over the subcores recovers the large-scale moduli. However, the standard deviation associated with the randomness of joint-subcore intersection can in some case be very large (potentially unlimited) which explains the observed variability.
Amadei, B. (1983) Lecture notes in engineering – rock anisotropy and theory of stress measurements. C.A. Brebbia, S.A. Orszag (editors), Berlin, Springer, pp. 233–241.
Amadei, B. and Goodman, R.E. (1982) The Influence of Rock Anisotropy on Stress Measurements by Overcoring Techniques, Rock Mechanics, 15, pp. 167–180.
Borsetto, M., Martinetti, S. and Ribacchi, R. (1984) Interpretation of in situ stress measurements in anisotropic rocks with the doorstopper method. Rock Mechanics and Rock Engineering, 17, pp. 167–182.
Dight, P.M. and Dyskin, A.V. (2007) Accounting for the effect of rock mass anisotropy in stress measurements. Deep Mining 07, Proceedings 4th International Seminar on Deep and High Stress Mining, Y. Potvin (editor), Australian Centre for Geomechanics, pp. 415–424.
Goodman, R.E. (1963) Subaudible noise during compression of rocks. Bull. Geol. Soc. Am. 74, pp. 487–490.
Hakala, M., Kuula, H. and Hudson, J.A. (2007) Estimating the transversely isotropic elastic intact properties for in-situ stress measurement data reduction: A case study of the Olkiluoto mica gneiss, Finland. Int. Jnl. Rock Mechanics and Mining Sciences, 44, pp. 14–46.
Jaeger, J.C., Cook, N.G.W. and Zimmerman, R.W. (2007) Fundamentals of Rock Mechanics. Backwell Publ., 475 p.
Kurita, K. and Fujii, N. (1979) Stress memory of crystalline rocks in acoustic emission. Geophys. Res. Lett. 6, pp. 9–12.
Lavrov, A. (2002) The Kaiser effect in rocks: principles and stress estimation techniques. Int. Jnl. Rock Mech. Min. Sci., 40, pp. 151–171.
Lekhnitskii, S.G. (1977) Theory of Elasticity of an Anisotropic Body. Mir, Moscow, 415 p.