ga = adjusted unit weight for a groundwater table (Eq. 6.7)
gb = buoyant unit weight of saturated soil below the groundwater table
gt = total unit weight of the soil
s′ = effective stress
sh = horizontal total stress
s′ h = horizontal effective stress
s′ n = effective normal stress on the shear surface
sv = vertical total stress
s′ v, s′ vo = vertical effective stress
s′ vm = maximum past pressure, also known as the preconsolidation pressure
Δsv = increase in vertical stress
tf = shear strength of the soil