DYNAMIC STRENGTH-DEFORMATION PROPERTIES OF MUDSTONE WITH WEAK PLANE

To clarify mechanical properties in particular strain rate dependency and cyclic effect on strength and deformation of mudstone with weak plane, triaxial and cyclic triaxial compression tests are performed on specimens which has discontinuous plane with variable angle θ to the maximum principal stress plane. We mainly describe dependency of strength and deformation on the angle, and deformation characteristics during cyclic loading, and strain rate dependency of strength and Yong's modulus. Particularly, it is found that maximum deviator stress (σ1-σ3)f at θ=60° nearly equals the residual strength, and rate dependency of strength clearly can be seen for the wide of strain rates, and (σ1-σ3)f at θ=60° can be given by failure criterion for residual strength of intact specimen based on effective stress.