GGU-2D-TRANSIENT: "Soil properties" menu item

After going to this menu item a system-specific dialog box opens allowing input of the transient soil properties. The steady-state properties imported from the GGU-2D-SSFLOW program can no longer be amended here.

Horizontal-plane systems:

For a horizontal-plane system the dialog box displays the soil properties defined by the user in GGU-2D-SSFLOW. It includes a further variable requiring user input: the specific storage coefficient of the fluid and the grain skeleton Ss.

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The soil permeability can be altered as a function of the time using the "k = f(t) [0]" button.

Vertical-plane and axis-symmetrical systems:

The dialog box for a vertical-plane or axis-symmetrical system corresponds to the previous box. Here, too, the steady-state soil properties are supplemented by the specific storage coefficient of the fluid and the grain skeleton Ss.

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The value for n_w can also be entered here. The value of n_w gives the volume of water relative to the total volume. It is a dimensionless variable and is a function of the pore water pressure u. Typical function curves for various soil types are shown in Figure 1:

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Figure 1  Function curves n_w = f(u)

By clicking the "nw = f(u)" button you will arrive at the following dialog box:

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The table offers you the possibility of developing the specific soil curve of the soil to be processed by assigning various pore water pressures u to n_w values. By clicking on the "x modelling points to edit" function box you can edit the number of modelling points. The entered values are adopted for all soil layers after an additional confirmation if the "Apply to all" button is clicked.

Alternatively to manual input, the default values for the various soil types (gravel, sand, silt, clay) can be automatically adopted by the program by pressing the "Std" button in the above "Soil properties" dialog box.