Consequences of seismic excitation on slopes in soils with a tensile strength cutoff

The yield criterion typically employed in slope stability analyses is the Mohr-Coulomb function with internal friction angle and the cohesion as the two strength parameters. The implication of this yield function is the presence of the tensile strength. However, it is doubtful whether geotechnical design should rely on the existence of tensile strength in soils, and models such as Cam clay do not allow uniaxial tensile strength in soils. It is demonstrated that eliminating tensile strength from the yield condition leads to a reduction in the stability factor. This is because the absence of tensile strength allows a larger variety of admissible failure surfaces. Seismic excitation produces the load that amplifies adverse consequences of the absence of the tensile strength. Two types of mechanisms are considered: translational and rotational. Examples of analyses with both types of collapse mechanisms are presented using the kinematic approach of limit analysis.