A simple analysis of 3D rock wedge

The failure of (three-dimensional) rock wedge occurs when two discontinuities strike obliquely across the slope face and their line of intersection daylights in the slope face. The rock wedge resting on these discontinuities may slide down along the line of intersection, provided that the inclination of this line is significantly greater than the sliding angle of friction. Alternatively the wedge may slide on any plane of discontinuity. Further, the wedge may fail by floating due to high seepage pressures on the joints.