Bolt Failure Modes
There are six bolt failure modes that can be reported in RocPlane:
- Pullout
- Tensile
- Stripping
- Shear
- User Defined
- Compression
NOTE: The term "Failure" as used here does not necessarily mean that a bolt has actually failed. It really refers to the potential failure mode of a bolt if wedge failure occurs. Remember that the RocPlane analysis is a limit equilibrium analysis. The actual stresses and deformations of the bolts are not computed.
Pullout / Tensile / Stripping Failure Mode
These are all tensile failure modes and are determined by the Bolt Force Diagram and the point at which a wedge plane intersects the bolt. For examples of Bolt Force Diagrams, see the Bolt Force Diagrams in RocPlane and the topics for the individual bolt types in RocPlane (Mechanically Anchored, Grouted Dowel, Cable Bolt, Split Set / Swellex).
Pullout, Tensile, and Stripping Bolt Failure Modes
Shear Failure Mode
The Shear Failure Mode is only reported if:
- The Use Shear Strength option is selected for a given bolt type.
- A bolt intersects a sliding plane of a wedge (as opposed to a dilating plane)
See Bolt Shear Strength in RocPlane and Bolt Support Force in RocPlane for more information.
Shear bolt failure mode
User Defined
If a Bolt Failure Mode is reported as User Defined, this simply means that the bolt (tensile) properties have been defined with a User Defined bolt type (i.e., the user creates an explicit Bolt Force Diagram rather than entering tensile properties).
NOTE: For a User Defined bolt type, it does not matter where a wedge plane intersects the Bolt Force Diagram. The Failure Mode is simply reported as User Defined. The specific modes of Pullout,Tensile, or Stripping are not reported.
Compression Failure Mode
The Compression Failure Mode is reported only under the following circumstances:
- The bolt intersects a sliding plane of a wedge and the Deformation Mode of the bolt is mode F (as illustrated in Bolt Support Force in RocPlane).
- Bolt Orientation Efficiency is ON.
- Bolt Shear Strength (Use Shear Strength check box) is OFF.
Only if all three of these conditions apply is Compression reported as the Bolt Failure Mode.