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GGU-UNDERPIN: Utilisation factor (buoyancy) using partial safety factors

Using the partial safety factor concept the following must be verified:

image-20241203-080824.png

  • Ak = the characteristic hydrostatic buoyant force acting on the lower surface of the
    complete structure, the soil layer in question or the excavation structure
  • γg,dst = partial factor for destabilising permanent actions in the UPL limit state
  • Gk,stb = lower characteristic value of stabilising permanent actions
  • γg,stb = partial factor for stabilising permanent actions in the UPL limit state
  • layer 1 (i = 1) is the uppermost layer

The so-called utilisation factor µ can also be calculated from this relationship.

image-20241203-080854.png

  • µN = utilisation factor of layer N

Utilisation factors ≤ 1.0 mean that sufficient safety is given.