rblock cut command
Syntax
- rblock cut keyword ... <range>
Primary keywords:
aspect-ratio fractures group intersects-box plane persistence size sliver-group sliver-intact sliver-remove
Cut the rigid blocks in range. This is accomplished by cutting the core shape with planar slices. One can either cut by a single plane or by fractures in a DFN. As the blocks are convex, a cut by a single plane or fracture can only result in two convex rigid blocks. A number of criteria are provided to determine if the rigid blocks resulting from a cut are retained; rigid blocks not meeting the criteria are deemed slivers. The presence of slivers may negatively impact performance so they should be avoided. The sliver criteria include: distance of cut points from the specified point on the cut plane, aspect ratio of the resulting blocks, minimum {area in 2D, volume in 3D} of the resulting blocks, or minimum ratio of resulting block {area in 2D; volume in 3D} to the original block {area in 2D; volume in 3D}. Slivers may either be deleted or, if a sliver is detected, the cut can be deemed unsuccessful and the original rigid block retained (see the sliver-remove keyword). Global persistence is also added (see the persistence keyword) so that the success of a cut may determined probabilistically.
Note
- Only the core shape is cut.
- While cycling, rigid blocks can only be cut before cycle point 0 (i.e., when the timestep is calculated).
- aspect-ratio f
Specify the maximum aspect ratio of the rigid blocks resulting from a cut to produce a sliver. The default value is 100.
- fractures <s > <keyword ...>
Cut rigid blocks with fractures. If the optional DFN name s is given only fractures from the specified DFN are used. By default all cut vertices must fall within a fracture for a cut to be successful. This is equivalent to stating that the fracture must cut the entire block. The optional throughgoing keyword specifies that a rigid block will be cut if the fracture intersects the rigid block at all. Thus a small fracture entirely inside a rigid block may cut the block. The optional infinite-plane keyword specifies that each fracture is treated as an infinite plane. Fractures are processed one at a time by decreasing fracture area.
- infinite-plane
Treat each fracture as an infinite plane, cutting the entire model. Cannot be given with the throughgoing keyword.
- throughgoing
Fractures cut rigid blocks that they intersect. Cannot be given with the Infinite-plane keyword.
- group s <slot slot >
The group slot slot is set to s for the cut rigid blocks. If slot is not specified, then s is assigned to the group slot Default.
- intersects-box fxmin fxmax <fymin fymax <fzmin fzmax >> (z-components are 3D ONLY)
Restrict cutting to the rigid blocks that intersect the specified box. Following specification of the extent of the box in the x-direction, if subsequent extents are omitted, then the latest specified extent is used.
- plane keyword ...
Cut all blocks in range by a single plane.
- normal vnorm
Specify the normal of the plane. By default the normal points in the positive {y-direction in 2D; z-direction in 3D}.
- point vpt
Specify a point on the plane. Be default the point on the plane is the origin.
- persistence f
Specify the persistence of the cut. If a cut is successful, a uniform random number is selected to model persistence; if this value is greater than or equal to f the cut is abandoned and the original rigid block is retained. The default value is 1.0.
- size keyword
Specify size parameters for a cut to be deemed successful.
- absolute f
Specify the absolute minimal {area in 2D; volume in 3D} of a rigid block resulting from a cut to produce a sliver. The default value is 0.0.
- sliver-group s <slot slot >
The group slot slot is set to s for the cut rigid blocks that are deemed slivers. If slot is not specified, then s is assigned to the group slot Default. If rblocks are kept intact (using the sliver-intact keyword) then this group will be assigned to any intact rblocks where cuts would have created slivers.
- sliver-intact b
Specify the behavior when a sliver is encountered. The cut is deemed to produce a sliver if either: 1) the aspect ratio of one of the resulting rigid blocks is larger than the value specified with the aspect-ratio keyword; 2) the ratio of the {area in 2D; volume in 3D} of one of resulting rigid blocks to the original rigid block is smaller than the value specified with the size relative keywords; or 3) the {area in 2D; volume in 3D} of one of resulting rigid blocks is smaller than the value specified with the size absolute keywords. If a sliver condition is detected then, if b is true, the cut will be deemed unsuccessful and the original rblock will be kept. This keyword should not be used with the sliver-remove keyword.
- sliver-remove b
Specify the behavior when a sliver is encountered. The cut is deemed to produce a sliver if either: 1) the aspect ratio of one of the resulting rigid blocks is larger than the value specified with the aspect-ratio keyword; 2) the ratio of the {area in 2D; volume in 3D} of one of resulting rigid blocks to the original rigid block is smaller than the value specified with the size relative keywords; or 3) the {area in 2D; volume in 3D} of one of resulting rigid blocks is smaller than the value specified with the size absolute keywords. If a sliver condition is detected then either the block that is a sliver may be deleted (if b is true) or the sliver may be retained (if b is false). By default slivers are removed. This keyword should not be used with the sliver-intact keyword.
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