Water Table & Piezometric Lines
Define the water table and piezometric lines that drive pore-water pressure.
Define the water table and piezometric lines that drive pore-water pressure.
Pore-water pressure is supplied to the solver by water-pressure surfaces. JW Slope supports two kinds: a single global water table and any number of named piezometric lines. Each material chooses which surface it reads its pore pressure from.
Water table
The water table is a single open polyline representing the phreatic surface. It needs at least 2 points. There is one water table per model.
To draw it:
- Click Add Water Table.
- Place vertices across the model, or type coordinates in the command input.
- Click Done Water Table.
Use Clear Water Table to remove it.
Piezometric lines
Piezometric lines are additional pressure surfaces, useful when different layers respond to different pressure heads. Each line needs at least 2 points and is given a name automatically, following the pattern P1, P2, P3, … in the order they are created.
To draw a piezometric line:
- Click Add Piezo Line.
- Place vertices, then click Done Piezo Line.
Use Clear Piezo Lines to remove all of them.
How materials reference a surface
Pore pressure is assigned per material, not globally. Each material has a water surface setting that selects one of:
| Setting | Effect |
|---|---|
| No Pore Pressure | The material is treated as dry (zero pore pressure). |
| Water Table | The material reads pressure from the global water table. |
| A piezometric line (P1, P2, …) | The material reads pressure from that specific line. |
This lets one model drive different layers from different surfaces — for example, an upper unit on the water table and a confined unit on a piezometric line.
Pressure coefficients
The water surface setting selects which surface a material reads. How that surface is converted into pore pressure — including Hu coefficients and the option for no pore pressure — is covered under material water properties. See the Materials documentation.
Related
- Water Properties (Materials)
- Tension Cracks — can follow the water table.