Study on shear-weakening behavior of rock joints

Shuilin Wang

In the proceedings of: GeoVancouver 2016: 69th Canadian Geotechnical Conference

Session: FUNDAMENTALS - III Soil & Rock Mechanics

ABSTRACT: In order to understand the mechanical characteristics of rock joints, the direct shear tests are usually carried out and the corresponding complete shear stress-displacement curves are obtained. Normally, the strength-weakening in post-peak part is observed in shear stress-shear displacement curve. Meanwhile, dilatancy is accompanied in normal displacement-shear displacement curve. In the shear stress-displacement curve, the maximum shear stress represents the peak shear strength and the shear stress in the residual part indicates the residual strength. Therefore, the negative slope locus means that the shear strength decreases from the peak to the residual strength. An approach for modeling strength-weakening behaviour is introduced in the paper. The shear stress-displacement curve in the post-peak part is approximated in a stepwise way to represent the strength-weakening, and the post-peak process is simplified as a series of stress drop and plastic flow during the increase of shear displacement. The relationship between strength-weakening process and the post-peak locus is studied, and the influence of dilatancy angle on the normal displacement is analyzed.

RÉSUMÉ: Afin de comprendre les caractéristiques mécaniques des joints rocheux, les essais de cisaillement direct sont habituellement effectués et les courbes de la contrainte de cisaillement-déplacement complet correspondantes sont la contrainte de cisaillement en cisaillement. Pendadéplacement normal en cisaillement. Dans la courbe de contrainte de cisaillement-déplacement, la contrainte de cisaillement maximale représente la résistance au cisaillement de pic et la contrainte de cisaillement dans la partie résiduelle indique la résistance résiduelle. Par conséquent, le locus de pente négative signifie que la résistance au cisaillement diminue après avoir culminé à la résistance résiduelle. Une approche pour la modélisation de comportement force-affaiblissement est introduite dans le livre. La courbe de contrainte de cisaillement-déplacement dans la partie post--pic .

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