Factor A

The stability graph method’s factor A, also known as the “Rock Stress Factor” was initially designed to replace the “Stress Reduction Factor” in Q (1974) [1].

Depending on which version of the “Stability Graph Method”, factor A can be calculated differently.

Figure 1: Rock Stress Factor A (Potvin, 1988) [2] for Stability Graph analysis.

Figure 2: Rock Stress Factor A (Villaescusa, 2014) [3] for Stability Graph analysis.

Anyhow, all methods share the same way of estimating the maximum Tangential Induced Stress acting on a wall.

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References

[1]

N. Barton, R. Lien, and J. Lunde. Engineering classification of rock masses for the design of tunnel support. Rock Mechanics, 6(4):189–236, 1974. doi:10.1007/BF01239496.

[2]

Yves Potvin. Empirical Open Stope Design in Canada. PhD thesis, University of British Columbia, Vancouver, Canada, 1988. Available online at the UBC Open Collections. URL: https://open.library.ubc.ca/collections/ubctheses/831/items/1.0051179.

[3]

Ernesto Villaescusa. Geotechnical Design for Sublevel Open Stoping. CRC Press, Boca Raton, FL, 1st edition, 2014. ISBN 9781482211887. doi:10.1201/b16702.