zone gridpoint pore-pressure command

Syntax

zone gridpoint pore-pressure keyword <range>

Primary keywords:

geometry    head    cutoff    import    initialize    plane    table

Assign or initialize values of pore-pressure to all gridpoints in the range.

Note in all cases saturation will be modified, if possible, to be consistent with the assigned pore pressures. If the cutoff model is present and a pore pressure below the tension is attempted to be assigned – the pore pressure at the gridpoint will be assigned the cutoff value and the saturation will be set to the cutoff value.

Available keywords are:

geometry <filename ...> sname <keyword ...> <range>

Specify the pore-pressure as increasing due to gravity with depth below a geometry set. If the filename keyword is used then name refers to a geometry file that will be loaded, used to determine the surface, and then discarded. For each gridpoint a ray is cast in the opposite direction of gravity. The first intersection with the geometric set sname determines the depth.

If no intersection is found the grid-point is considered to be above the geometry and will be assigned a negative pore pressure, unless the cutoff keywords is used.

See the geometry command for how to create, import, or modify geometric data.

cutoff <f >

Specify the minimum cutoff of pore pressures assigned. If not value is given 0.0 is assumed. The default value is no limit.

density f

Specify the fluid density to use in the conversion of depth below plane to pore-pressure. If not specified the value given by the zone fluid-density command is used. A non-zero fluid density must be available in order to specify pore-pressure with the plane keyword. This keyword is a synonm for fluid-density.

fluid-density f

Specify the fluid density to use in the conversion of depth below plane to pore-pressure. If not specified the value given by the zone fluid-density command is used. A non-zero fluid density must be available in order to specify pore-pressure with the plane keyword. This keyword is a synonm for density.

effective <b >

By default the total stress is held constant, so any change to pore-pressure results in a change of effective stress in connected zones. If the effective keyword is used then effective stress is held constant and the total stress is adjusted in connected zones.

head f <keyword ...> <[gridpointporepressureblock]>

Uses Head to initialize pore pressure at gridpoint. Pore-pressure is calculated from head using the formulat \(p = \rho[h|\vec{g}| + (\vec{x}-\vec{d})\cdot\vec{g}]\) where \(p\) is the pore-pressure, \(\rho\) is the fluid density, \(h\) is the specified head, \(\vec{g}\) is gravity, \(\vec{x}\) is the position of the current gridpoint, and \(\vec{d}\) is the datum. The following keywords are available:

cutoff <f >

Pore-pressure values are not allowed to fall below this cutoff value. If no value is given 0.0 is assumed. The default cutoff is no limit.

datum v3 | f

Specify the datum to use as the origin for purposes of calculated head height. The default value is the origin. Note that if only a single floating point value is given it is assumed to specify a location starting from the origin in the opposite direction of gravity for that many units.

density f

Specify the fluid density to use in the conversion of head to pore-pressure. If not specified the value given by the zone fluid-density command is used. A non-zero fluid density must be available in order to specify pore-pressure with the head keyword. This keyword is a synonm for fluid-density.

effective <b >

By default the total stress is held constant, so any change to pore-pressure results in a change of effective stress in connected zones. If the effective keyword is used then effective stress is held constant and the total stress is adjusted in connected zones.

fluid-density f

Specify the fluid density to use in the conversion of head to pore-pressure. If not specified the value given by the zone fluid-density command is used. A non-zero fluid density must be available in order to specify pore-pressure with the head keyword. This keyword is a synonm for density.

import sfile <keyword ...>

Import values from a file and use the data to assign pore-pressues to a grid-point. sfile is the file name. Currently two formats are supported. MineDW files (which end in .mdp) and comma separated values files (which end in csv).

When importing from csv files the data is assumed to be arranged in columns using (x,y,z,pressure) order.

When importing from MineDW files, any gridpoint that falls outside of any MineDW zones are skipped.

The following keywords are available:

cutoff <f >

Pore-pressure values are not allowed to fall below this cutoff value. If no value is given 0.0 is assumed. The default cutoff is no limit.

geometry

If this keyword is given, then geometric data representing the pore-pressure is created. MineDW nodes and zones will be created in a geometric set named MineDW. Nodes and edges are created only. Unstructured imported points are added as nodes only to a geometry set called PorePressure. The first extra variable of the node will be assigned the pore-pressure value.

scale-position f

Scale the components of the position vector of the individual points by multiplying by the scalar f. This scale operation is performed after the translate operation. The default value is 1.0.

scale-pressure f

Scale the pore-pressure by multiplying by the scalar f. This scalar operation is performed after the cutoff operation. The default value is 1.0.

translate v

If this keyword is used, the node lcoations in the file will be translated by the specified vector on import. The default value is \((0,0,0)\). The translate is applied before the scale operation if scale-pressure is given.

initialize f <[gridpointporepressureblock]>

Set the pore-pressure values in the grid-points of the range to f.

cutoff <f >

Pore-pressure values are not allowed to fall below this cutoff value. If no value is given 0.0 is assumed. The default cutoff is no limit.

plane <keyword ...>

Specify the pore-pressure as increasing due to gravity by depth from a single plane in space. Pore pressures above the plane can be set to a negative value, unless the cutoff keyword is used. The following keywords are available:

cutoff <f >

Pore-pressure values are not allowed to fall below this cutoff value. If no value is given 0.0 is assumed. The default cutoff is no limit.

origin v

Specify the origin of the plane describing the \(p = 0\) surface. By default this value is \((0,0,0)\).

normal v

Specify the vector normal to the surface of the plane describing the \(p = 0\) surface. By default this is \((0,0,1)\). This vector need not be normalized.

density f

Specify the fluid density to use in the conversion of depth below plane to pore-pressure. If not specified the value given by the zone fluid-density command is used. A non-zero fluid density must be available in order to calculate pore-pressure. This keyword is a synonym for fluid-density.

fluid-density f

Specify the fluid density to use in the conversion of depth below plane to pore-pressure. If not specified the value given by the zone fluid-density command is used. A non-zero fluid density must be available in order to calculate pore-pressure. This keyword is a synonym for density.

effective <b >

By default the total stress is held constant, so any change to pore-pressure results in a change of effective stress in connected zones. If the effective keyword is used then effective stress is held constant and the total stress is adjusted in connected zones.

table sname <keyword ...> <range>

Specify the pore-pressure as increasing due to gravity with depth below a table. It is assumed that x is the horizontal direction and y (2D) or z (3D) is the vertical direction and that gravity acts in the negative y (or z) direction. The pore pressure is calculated by taking the x-coordinate of each gridpoint and calculating the depth below the table at that x location. Fluid density must be given as part of the command or before this command.

If the gridpoint is above the table, it will be assigned a negative pore pressure, unless the cutoff keyword is used.

See Table for how to create, import, or modify table data.

cutoff <f >

Specify the minimum cutoff of pore pressures assigned. If not value is given 0.0 is assumed. The default value is no limit.

density f

Specify the fluid density to use in the conversion of depth below plane to pore-pressure. If not specified the value given by the zone fluid-density command is used. A non-zero fluid density must be available in order to calculate pore-pressure. This keyword is a synonym for fluid-density.

fluid-density f

Specify the fluid density to use in the conversion of depth below plane to pore-pressure. If not specified the value given by the zone fluid-density command is used. A non-zero fluid density must be available in order to calculate pore-pressure. This keyword is a synonym for density.

effective <b >

By default the total stress is held constant, so any change to pore-pressure results in a change of effective stress in connected zones. If the effective keyword is used then effective stress is held constant and the total stress is adjusted in connected zones.

zone gridpoint pore-pressure Keyword Block

The following keywords may be used to modify a supplied value. If the description of the modifier keyword mentions what type of value it may be applied to (e.g. scalar value, vector value, etc.), be sure there is a match between the modifier and the main keyword value. The commands main keywords are: head and initialize.

add

Add the specified value to the existing value.

gradient v <origin v >

Apply a gradient to the scalar-value provided.

local

Specify that the value supplied for the keyword is in the local coordinate system of the gridpoint (if any). By default values are initialize in the global system.

multiply

Multiply the existing value by the specified value.

vary v

Apply a linear variation to the scalar-value provided.

cutoff f

Pore-pressure values are not allowed to fall below this cutoff value. The default cutoff is 0.

effective <b >

By default the total stress is held constant, so any change to pore-pressure results in a change of effective stress in connected zones. If the effective keyword is used then effective stress is held constant and the total stress is adjusted in connected zones.