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# Anisotropic Strength

The Anisotropic Strength model allows you to define Anisotropic strength properties for a soil or rock mass, by defining cohesion and friction angle in two orthogonal planes.

Required parameters are:

• Cohesion 1 and Phi 1 - cohesion and friction angle in the plane defined by the dip and dip direction of Plane 1
• Cohesion 2 and Phi 2 - cohesion and friction angle in any plane perpendicular to Plane 1
• Dip of Plane 1 / Dip Direction of Plane 1 - this defines the orientation of a plane in 3 dimensions, in which the strength parameters cohesion 1 and phi 1 are applicable. Typically this will be a plane of weakness.

NOTE: Dip Direction of Plane 1 is the azimuth of the plane with respect to north (north = zero degrees). In a Slide3 model, the y-axis is always the north direction. Therefore you must define the dip direction accordingly.

The cohesion and friction angle for any arbitrary plane is then given by:

where alpha ( a ) = the minimum (acute) 3-dimensional angle between Plane 1 and the shear plane (e.g. column base plane).

The Anisotropic Strength model in Slide3 could also be referred to as Transversely Isotropic Strength.

## Tensile Strength

See the Tensile Strength topic.

## Generalized Anisotropic Strength

A more general anisotropic strength criterion can be defined with the Generalized Anisotropic failure criterion option.