Abstract
This paper contains a discussion of the macroscopic shearing strength of brittle materials in the discontinuous state such as joint systems or stratification in the materials.
The plaster-sand model tests have been performed by the application of two types of direct shear test (box shear test and rock shear test) for jointed and stratified specimens in order to investigate their failure mechanism and anisotropy of the macroscopic shear strength and the dilatancy.
These tests have made it clear that the macroscopic shear strength is affected by the failure mechanism which depends upon the movement of fractured particles after the crack formation around the joints or in the strata. The apparent resistances to the shear force for the jointed or stratified materials with positive inclination to the fictitious shear plane are less than for the materials with negative inclination.
The jointed materials possesses less sensitivity against the anisotropy of strength and dilatancy with respect to the direction of discontinuous planes compared to the stratified materials.
