Wedge geometry¶
The wedge is a 2D rigid body analysed per metre of development along the crest.
Frame and notation¶
| Symbol | Meaning |
|---|---|
| O | toe of the slope, origin of the coordinate system (0, 0) |
| +X | toward the mountain (intact rock) |
| +Y | vertical, upward |
| B | crest of the slope face |
| C | top of the failure plane on the upper bench |
| D | top of the tension crack (only with TC) |
Input parameters¶
| Parameter | Symbol | Units | Notes |
|---|---|---|---|
| Slope height | H | m | from toe O to crest B |
| Slope face dip | β | ° | typically 60–90° for rock |
| Failure plane dip | α | ° | from horizontal; must satisfy α < β (daylighting) |
| Upper face dip | ψ | ° | 0 = horizontal bench; positive = rising toward the mountain |
| Block depth | B | m | length perpendicular to the section; scales results to totals |
Tension crack (optional)¶
Toggle to define a TC and fill in:
- T — distance of the TC from the crest [m]
- θ — crack dip [°] (90° = vertical, 70° = back-tilted, etc.)
The TC introduces an extra water force V in the joint (if Zt > 0) and shortens the failure plane.
Computed geometry¶
The right column shows:
- L failure plane length (O → C without TC, O → D with TC)
- M upper bench length (B → C or B → D)
- Q tension crack length
- A wedge area (per metre of section)
- (xg, yg) centroid coordinates
- W weight per metre = γ · A
α critical¶
Use the α crit button to automatically find the failure plane dip that minimises FS within the kinematically admissible range. Read more →