Add Joint Network

A joint network is created with the Add Joint Network option. This allows you to generate a joint network in any selected region(s) of the model. Multiple joint networks can be defined, and different networks can be applied to different regions if desired.

To add a joint network:

1. Select Add Joint Network from the toolbar or the Joint Networks sub-menu of the Boundaries menu.
2. Use the mouse to select the region(s) of the model where you would like to generate a joint network. When a region is selected it will be temporarily highlighted by a hatch pattern. Note:
3. • You can click inside any closed region of the model to select the region.
   • Selection works as a toggle - if you accidentally select a region you can click again in the region to de-select it.
   • You can select multiple regions of the model by clicking and dragging a selection window.
4. When you are finished selecting region(s) press Enter or right-click and select Done.
5. You will see the Add Joint Network dialog, which allows you to define the properties of the joint network you wish to add. You will also see a preview of a joint network displayed directly on the model. The preview corresponds to the currently selected joint network parameters in the Add Joint Network dialog.
6. In the Add Joint Network dialog, first select the desired Joint Model, as this determines the type of joint network you can define.
7. Enter the joint network parameters as described below. Notice that as you change the parameters, the joint network preview displayed on the model is automatically updated. If you wish to turn off the automatic preview update, you can clear the Update Preview check box at the bottom of the dialog. See below for details.
8. When you are finished defining the network properties, select [OK] and the joint network will be applied to the region(s) selected in step 2.

The input parameters and options which are common to all networks are described below. For details about the individual parameters for each Joint Model, see the corresponding help topic for each model.

Joint Model

The Joint Model determines the type of joint network you would like to define. Before you enter any other joint network parameters, you should select the Joint Model because this determines the parameters which can be entered. The following joint network models are available:

• Parallel Deterministic
• Parallel Statistical
• Cross Jointed
• Baecher
• Veneziano
• Voronoi

For details about the parameters of each model, see the above links.

Note: if your joint network consists of multiple joint sets (see below), then you can choose different parameters for each joint set, if desired.

Installation Stage

For a multi-stage model (i.e. Number of Stages > 1) you can choose the Installation Stage of the joint network by entering the desired stage number.

• For natural joints in a rock mass, normally you would leave the Installation Stage = 1 (i.e. the joint network exists from the first stage of the model).
• If you wish to define a joint network that is created at a particular stage then you can enter the desired Installation Stage > 1. This could be used to simulate rock that is fractured or failed at a particular stage, for example.

If you define an Installation Stage > 1 then the network will exist at the Installation Stage and all subsequent stages (unless the material is excavated). The joint network will NOT exist for stages prior to the Installation Stage; this will be indicated by a lighter shade of colour used to display the joint boundaries prior to the installation stage.

For a single stage model the Installation Stage option will not be available.

Note: if your joint network consists of multiple joint sets (see below), then you can enter a different Installation stage for each joint set, if desired.

Joint Property

The Joint Property determines the physical properties (e.g. strength, stiffness) of all joint boundaries in the network. The joint properties are entered in the Define Joint Properties dialog.

Note: if your joint network consists of multiple joint sets (see below), then you can select a different Joint Property for each joint set, if desired.

Joint End Condition

The Joint End Condition allows you to specify the end condition (Open or Closed) of each joint boundary in a joint network.

Closed Joint End

If a Joint end is Closed, this means that the end of the Joint boundary is represented by only ONE node in the finite element mesh, and therefore relative movement (sliding or opening) cannot occur at the joint end.

Open Joint End

If a Joint end is Open, this means that the end of the Joint boundary is represented by TWO nodes in the finite element mesh, which can move with respect to each other.

For a joint network, you can choose one of the following options for Joint End Condition:

• All Closed - the ends of all joint boundaries in the network will be closed. This is the default setting.
• All Open - the ends of all joint boundaries in the network will be open.
• Open at Boundary Contacts - joint network boundaries which terminate at other model boundaries (e.g. ground surface, external, excavation, material, stage) can be specified as Open (Yes) or Closed (No) for each boundary type. Note that the ground surface boundary (i.e. the Surface option) is automatically determined by RS2 based on your model geometry and is useful for slope or open pit mine models, for example.

For further information about Joint End Condition see the Add Joint Boundary topic.

NOTE: the symbols used to indicate the Joint End Condition (Open or Closed) can be turned on or off in the Display Options dialog.

Multiple Joint Sets

A joint network in RS2 can consist of a single joint set or multiple joint sets. By default a joint network in RS2 represents a single joint set.

To define a joint network which consists of multiple joint sets:

1. Select the Use Multiple Joint Sets check box at the bottom left of the Add Joint Network dialog.
2. Select the Add button to create the desired number of joint sets. The joint sets are automatically numbered (1, 2, 3 ...) and are listed in the Joint Sets column at the left of the dialog.
3. To define the properties of each joint set, click on a joint set number in the Joint Sets column, and define the joint set properties as described above. Each joint set can have different properties (e.g. you can assign a different Joint Model, Joint Property, Installation Stage, etc., for each joint set in the network).
4. You can turn "off" any joint set by clearing the check box for the joint set. This allows you to quickly remove a joint set from the network, without deleting the properties you have defined.

NOTE:

• When you define multiple joint sets for a single joint network, ALL of the joint sets are considered to be part of the same network. This is relevant if you later wish to edit the joint network.
• You can also define multiple joint networks/sets in one region of the model by repeating the Add Joint Network process, independently for each network. See the Multiple Joint Sets topic for more information.

Auto Min/Max 3x Std. Dev.

If this check box is selected, then the relative minimum and relative maximum values for applicable statistical distributions, will automatically be set equal to 3 times the standard deviation. This is based on the fact that for a normal distribution, over 99% of samples are expected to fall within 3 standard deviations of the mean value. This option allows you to edit the standard deviation and automatically update the minimum and maximum to appropriate values.

If this check box is turned off, then the relative minimum and relative maximum values will NOT be automatically updated if the standard deviation is changed.

Update Preview

If the Update Preview check box is selected, then an updated preview of the joint network will automatically be displayed directly on the model, each time you enter or modify a parameter in the joint network dialog. The Update Preview check box is always ON by default.

Depending on the type of joint network you are defining (i.e. joint model, number of joints generated), it may take a substantial amount of time to generate the joint network (e.g. several seconds or longer). In such cases, you may not want to see the preview updated until you have entered all of the parameters. In this case, clear the Update Preview check box; the joint network preview will not be updated as you enter parameters, but only after you select [OK].

Randomize

When a joint network is generated, random sampling of statistical distributions may be used to generate the joint orientations, length, spacing and other parameters. The actual random variables will depend on the Joint Model and the variables to which a statistical distribution has been assigned. In most cases, one or more random variables will be used to generate a joint network (even for the Parallel Deterministic model, the location of the joints can be defined as a random variable).

When a joint network is initially generated, the resulting network is determined by an initial random sampling of the random variables.

You can re-generate a new network at any time by clicking the Randomize button. This will re-sample all random variables of your Joint Model and generate a new joint network, based on the statistical distributions of the random variables you have defined. The Randomize option can be used at any time to re-generate a joint network, or if you simply wish to visualize the changing joint networks which result from repeated random sampling.

NOTE:

• If the joint network is not updated when you select the Randomize button, make sure that the Update Preview check box is turned on (see above).
• If your joint network consists of multiple joint sets (see above), the Randomize option applies independently to each joint set (i.e. only the currently selected joint set will be re-generated). To simultaneously re-generate all joint sets in a joint network, you can select the Randomize (All Joint Sets) option from the drop-list menu beside the Randomize button.

Random Seed

Sequences of random numbers used in statistical sampling are determined by a random number generation algorithm and an initial seed value. If you select the drop-arrow beside the Randomize button, you can edit the Random Seed value or reset the default value. If you change the seed value, you will generate different values of the random variables, and obtain a different joint network.