Abstract

Triaxial tests were conducted on the schist specimens with various anisotropic angles under confining pressures of 0, 7 and 15 MPa, and axial stress-axial strains, were measured and plotted for various conditions.

The results obtained reveal the effects of schistose on the strength and deformability of the rock very clearly. Peak strength of the specimens for 0° and 90° schistose orientations are nearly the same. Modulus of elasticity of this rock varies with anisotropic angle. For 0 orientation modulus of elasticity increases to a maximum. Confining pressure increases the peak strength and improves the rock deformability. However, this effect is not the same for various orientations, and there are no similar trends for each anisotropy direction.

Analysis of the results shows that consideration of a linear failure criterion such as Mohr-Coulomb is appropriate for the prediction of rock behaviour up to 10 MPa, rather than a non-linear one. The analysis also reveals that the friction angle and cohesion are affected by the anisotropy orientation, and this effect is more important for the cohesion than the friction angles.

Resume

Les esseys triaxiales sur les echantillon d un roch schist avec les differents angles non-isotrop sous les tension lateral zero et sept et qoinze mega pascal (mpa) est fait et les covtraite et allongment unitaire sont mesure et leur curues est destine sous different condition les resultats obtenues montre les effets du schistosite sur le resistance et le ductilite vissiblement.

Le resistance final sur les echantilions pour les angles o degre et 90 degree est equivalent. Le modoule d elasticite de ce roch sera difere par a port de l angle de stratification. Pour l angle o degree le valeur de modoule est le maximum. le pousse lateral augmenterai le resitance final, et sera amilterai le toleran le de ductilite. Mais cette effet bn est pas unigue pour les different stratification, et pour les diferents directions no- isotrop it n y a pas le meme solution.

L analyse des resulitats montre que le criterre de ruin comme mohr-colomb est moderate pour le pousse lateral jusq av lo mega pascal, et ce n est pas neccesaire d utiliser de criterre no-linear.

Abriß

Dreiachsige Pruefung wurde auf den schist Exemplaren mit verschiedenen anisotropic Winkeln unter Bestatigen von Druecken von 0.7 und 15 MPa geleitet, und axiale Spannung axiale Spannungen, wurden gemessen und fuer verschiedene Bedingungen wurde geplant. Die Ergebnisse haben die Wirkungen von schisocity auf der Kraft und dem deformability des Felsen sehr deutlich erhalten offenbart. Maximale Kraft der Exemplare fuer 0° und 90 sind° schistos Orientierungen beinahe das gleiche. Modulus der Elastizitat von diesem Felsen andert sich mit anisotropic Winkel. Fuer 0° vermehrt Orientierung modulus der Elastizitat zu einem Maximum. Einschrankender Druck vermehrt die maximale Kraft und verbessert den Felsen deformability.

Aber ist diese Wirkung nicht das gleiche fuer verschiedene Orientierungen, und es gibt keine ahnlichen Tendenzen fuer jede anisotropic Richtung. Analyse der Ergebnisse zeigt jener Überlegung Kriterium eines linearen Ausfalls wie zum Beispiel Mohr Coulomb passend fuer die Voraussage von Felsen Verhalten bis zu 10 MPa, anstatt eines nicht linear ist. Die Analyse offenbart auch, daß der Reibung Winkel und Bindekraft werden beeinflußt von der anisotropic Orientierung, und diese Wirkung wichtiger fuer die Bindekraft ist, als der Reibung Winkel

Introduction

Rock masses are rarely homogeneous, isotropic and intact, as commonly assumed for other engineering materials (Serafim, 1966). Failure of rock masses, particularly near the surfaces, usually results from sliding along a single discontinuity or a combination of discontinuities (Farmer, 1983).

In most parts of the city of Isfahan in Iran, at a depth of 5 to 20 meters from the ground surface, schist is the predominant rock. Determination of the strength properties of this rock is of paramount interest, because many large factories, dams, conveyance tunnels, airports, and heavy buildings are under study and construction.

For the purpose of measuring strength and deformation properties of this rock, triaxial tests were conducted on the specimens with various anisotropy angles under confining pressures of 0, 7 and 15 MPa, and axial stress-axial strain were measured and plotted for various conditions.

The procedure used for preparation of test specimens was in accordance with the ISRM suggested methods (Brown, 1986). The specimens were cored to a nominal diameter of 45 mm and length of 90 mm. They were smooth and free of any abrupt irregularities, with sides parallel to each other to within 0.01 mm and at right angles to the longitudinal axis.

This content is only available via PDF.
You can access this article if you purchase or spend a download.