Water Condition for multi-layer excavation in Plaxis 3D

Dear All,

I am a newbie of Plaxis. I would like to ask about water condition "Global", "Dry", "Head" & "Interpolate" in 3D

When the model with multi-layer excavation 1 by 1, I would like to ask whether my logic in Plaxis correct or not:

Stage 1: Excavation of 1st Layer

Layer 1: Set "dry" and "deactivate"

Layer 2: Set "head" and Zref = 500mm below 1st excavation level

Layer 3: Set "interpolate"

Layer 4: Set "interpolate"

Soil below Layer 4: "Global"

Soil outside sheet pile wall: "Global"

Hope someone can help me.