FLAC3D Modeling • Introduction

How Commands Work

This section is a general description of commands, how they are constructed, their parts, how they operate with one another, and the like. It focuses on commands singly — as they are issued in the Console. Processing multiple commands in an uninterrupted flow via data file is described in detail in the section on Data Files. Command reference information is found throughout this documentation. Refer to the Command Index for specific commands; the topic Command Tools lists the multiple program facilities available for accessing reference information on commands and FISH functions.

Four general principles govern commands in the program.

  1. A command without a range will affect on all objects of the type it is designed to operate on.

  2. Commands are processed in the order given. Later commands overwrite previous ones.

  3. To restrict or “subset” a command’s operation, a range is required. The range is a filter composed of one or more criteria (including logical operators) that identifies the set of objects to be targeted in a command.

  4. Commands can be undone with the command program undo. This will cause all commands except the last (the undone command) to be rerun since the last restore. not sure UNDO rises to the level of being needed here, but this is a logical place for it.


The four principles above are neatly illustrated as follows.

zone cmodel assign mohr-coulomb
zone cmodel assign elastic
zone cmodel assign hoek-brown range position-x 1 500
program undo
  1. The first command assigns the mohr-coulomb constitutive model to all zones.

  2. The second command assigns the elastic model to all zones, overwriting the first command.

  3. The third command, on the other hand, assigns the Hoek-Brown model to zones with centroids whose \(x\)-components lies between \(x\) = 1 and \(x\) = 500. This command partially overwrites the second command in that, after complete, only zones outside the range given continue to have the elastic assignment.

  4. The fourth command will undo the third command. At this point, four commands have been processed, but the model state reflects execution of just the first two: all zones are assigned the elastic model.

The use of ranges and groups to refine the application of commands to targeted objects is further introduced in the next topic.

A full index of commands is available in the Command Index.