An Analytical Solution for Deformation of Underground Openings Excavated in Fractured Rocks

Amir R. Khoshboresh

In the proceedings of GeoSt. John's 2019: 72nd Canadian Geotechnical Conference

Session: Rock Mechanics

ABSTRACT: Excessive deformation of rock mass around underground openings are frequently encountered in mines and underground structures. It is particularly common in the tunnels excavated in soft rocks, the rock masses subjected to high in-situ stresses, and the weak rock masses that have been heavily sheared. Conventional approaches in the estimation of deformation in tunnels, such as Sulem et al. (1987), assumed that the tunnel is deep enough to consider that the stress distribution is homogeneous. However, in most cases in practice, the stress distribution around the tunnels are not homogeneous and isotropic. New correlations are therefore developed as part of this study1 to generalize the Sulem et al. equations by considering a non-homogeneous stress distribution (biaxial stress field) around the tunnel. The comparative results showed although the numerical results are very close to the analytical solution results, there is still a significant difference between the field data and analytical results.

RÉSUMÉ: Des déformations excessives de masse rocheuse autour des ouvertures souterraines sont fréquemment rencontrées dans les mines et les structures souterraines. Il est particulièrement commun dans les tunnels creusés dans des roches tendres, dans les masses rocheuses soumises à de fortes contraintes in situ et dans les masses rocheuses faibles fortement cisaillées. Les approches conventionnelles dans l'estimation de la déformation dans les tunnels, tel que Sulem et al. (1987), supposent que le tunnel est suffisamment profond pour considérer que la répartition des contraintes est homogène. Cependant, dans la plupart des cas, la répartition des contraintes autour des tunnels n'est ni homogène ni isotrope. De nouvelles corrélations sont donc développées dans le cadre de cette étude pour généraliser les relations de Sulem et al. équations en considérant une non homogène répartition des contraintes (champ de contraintes biaxiales) autour du tunnel. Les résultats comparatifs ont montré que, bien que les résultats numériques soient très proches des résultats de la solution analytique, il existe toujours une différence significative entre les données de terrain et les résultats analytiques.

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Cite this article:
Amir R. Khoshboresh (2019) An Analytical Solution for Deformation of Underground Openings Excavated in Fractured Rocks in GEO2019. Ottawa, Ontario: Canadian Geotechnical Society.

@article{Geo2019Paper187,author = Amir R. Khoshboresh,title = An Analytical Solution for Deformation of Underground Openings Excavated in Fractured Rocks ,year = 2019}