Shear Factor of Safety

This is the only failure mode considered in a Rigid analysis. The crown pillar or roof beam is treated as a rigid block (elastic properties are not considered), and the factor of safety of the pillar against vertical downward sliding is given by the ratio of the sum of the shear forces acting on the sides (i.e., abutments) of the pillar, to the total weight of the pillar, including overburden and free water, if any.

For a Rectangular Pillar, the Shear Factor of Safety is given by:

Shear Factor of Safety =

where,

The shear strengths and are determined based on the Strength Criterion and Lateral Stress parameters input by the user.

For a Polygonal Pillar, the Shear Factor of Safety is calculated by summing the shear resistances along each abutment face and dividing by the total deadload.