GGU-CANTILEVER: Hydraulic heave safety using global safety factors
The hydraulic heave safety for each layer below the excavation base is determined via a comparison of the soil weights to the flow forces at the respective layer bases.

ηN = hydraulic heave safety of the layer N
G'i = buoyant self-weight of layer i
SN = flow force of layer N
layer 1 (i = 1) is the uppermost layer
The minimum value of all ηN is the hydraulic heave safety of the system.