Triaxial compression of Ordovician slate materials in NW Spain
DOI:
https://doi.org/10.21701/bolgeomin.122.1.008Keywords:
anisotropy, slates, strength, triaxial compressionAbstract
This study describes the most significant results of an investigation into the resistance properties of slates from the Ordovician Casaio and Rozadais formations at the Truchas syncline in NW Spain, undertaken using triaxial compression tests. The most important differences in resistance proved to be due to the orientation of the anisotropy planes with regard to the principal axial load and also to the considerable influence of lithological variations in the slate samples themselves. According to the Mohr-Coulomb failure criterion, under saturated rock sample conditions, the slates of the Casaio formation at 0°, 90°, 10° and 25° angles of the foliation plane to the horizontal gave cohesion values of between 112 and 6.3 MPa, and internal friction-angle values of between 4° and 52°. Those from the Rozadais formation, with angles of foliation of 0° and 90°, gave cohesion values of between 51 and 18 MPa, and internal friction-angle values of between 44° and 29°. The resistance values recorded in this study when compared with those of isotropic rocks in the Cantabrian Zone show a far wider dispersion, due mainly to the different inclinations of the anisotropic planes, and so anisotropy has to be taken into consideration when assessing the stability of engineering structures built either upon or within these types of rock.
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References
AENOR 1999. Geotecnia. Ensayos de campo y de laboratorio. Ed. AENOR, Madrid, 385 pp.
González Buelga, M. T. 1995. Caracterización geomecánica y valoración geotécnica de materiales rocosos del Paleozoico inferior en la cuenca alta del Río Bernesga (León, Noroeste de España). Tesis doctoral Inédita, Biblioteca del Dpto. de Geología, Universidad de Oviedo, 445 pp.
González Buelga, M. T., Gutiérrez Claverol, M., Rodríguez Bouzo, L. y Torres Alonso, M. 1996. Comportamiento geomecánico de materiales paleozoicos bajo compresión triaxial (Zona Cantábrica, Macizo Ibérico). Geogaceta, 20 (6), 1328-1330.
González de Vallejo L. I., Ferrer, M., Ortuño, L. y Oteo C. 2002. Ingeniería Geológica, Pearson Educación, Madrid, 744 pp.
Hoek E. y Brown E.T. 1980. Empirical strength criterion for rock masses. J. Getech. Engng Div. ASCE 106 (GT9), 1013-1035. https://doi.org/10.1061/AJGEB6.0001029
Liao J.J. y Hsieh H.Y. 1999. Triaxial residual strength of an anisotropic rock. Vail Rocks The 37th U.S. Symposium on Rock Mechanics (USRMS), Balkema, Rotterdam.
Muschler, TH., y Natau, O. 1991. Further developments for the determination of the stress-strain behaviour of jointed rock mass by large scale tests. Proc. 7th Int. Congr. ISRM, Ed Aachen, vol. 3, 1557-1560.
Natau, O., Bühler, M., Keller, S. y Mustchler, Th. 1995. Large scale triaxial tests in combination with a FEM analysis for the determination of the properties of a transversal isotorpic rock mass. Proc 8th Int Congr ISRM, Tokio, 635-643.
Özsan A. y Karpuz C. 1996. Geotechnical rock-mass evaluation of the Anamur dam site, Turkey. Engineering Geology, 42, 65-70. https://doi.org/10.1016/0013-7952(95)00065-8
Ramamurthy T. 1993. "Strength and Modulus Responses of Anisotropic Rocks". En: Comprehensive Rock Engineering, principles, partice and projects. Volumen 3, Pergamon Press, 313-329.
Rodríguez Bouzo L.F. 1993. Caracterización geomecánica de materiales carbonatados del carbonífero en la zona de Parajes- Villamanín. Tesis doctoral Inédita, Biblioteca del Dpto. de Explotación y Prospección de Minas, Univ. De Oviedo, 416 pp.
Rodríguez Sastre, M. A. 2003. Caracterización geomecánica de materiales pizarrosos del Sinclinal de Truchas (León-Orense), Tesis doctoral inédita. Biblioteca del Dpto. de Geología, Universidad de Oviedo, 388 pp.
Shah S. y Hoek E. 1991. Rockdata v. 2.0. Manual, Universidad de Toronto, 21 pp.
Sheorey, P.R. 1997. Empirical Rock Failure Criteria. Balkema, Rótterdam, 176 pp.
Singh, M., Rao, K.S. y Rmamurthy T. 2002. Strength and Deformational Behaviour of a Jointed Rock Mass. Rock Mechanics and Rock Engineering, 35 (1), 45-64. https://doi.org/10.1007/s006030200008
Waltham, T. 2009. Foundations of engineering geology. Taylor & Francis, London and New York, 98 pp.
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