LAB 4B 3 of 5

Preparing a Stereographic Plot for Rock-Slope Failure Analysis

The discontinuity sets P1 through P6 have already been identified and plotted, and their dip directions and dip angles are tabulated.

The analysis considers four failure modes: circular, planar, wedge, and toppling. Circular failure is set aside because it is more relevant to soil or highly fractured rock. The discussion focuses on planar, wedge, and toppling failure in rock.

The example slope has a dip direction of 090° and a dip angle of 60°. The friction angle is 30°.

To construct the plot, mark the slope’s direction and dip on the stereonet, then add the friction-angle limit. The instructor demonstrates moving the tracing paper so the friction-angle marking can be drawn consistently along the slope representation.

Speakers and Sources

• One unidentified instructor or narrator explains the plotting procedure and failure modes.
• The segment refers to lab-provided data and criteria but does not identify a specific document or additional speaker.