Joint Materials and DFNs in 3DEC

3DEC Version 5 can build and use Discrete Fracture Networks (DFNs) to create joints in 3DEC models. But, because all blocks in 3DEC must be convex, cuts must split blocks entirely, even if the fracture only passes partway through the block. This problem is resolved by assigning properties to the subcontacts lying within the fracture that differ from those lying outside of the fracture — which is easily accomplished with the change dfn command.

A problem with this approach is the plotting of joint materials. Joint plots in 3DEC color joints by contact material number. But, with DFNs, it is possible to have some subcontacts with different material numbers than those of the host contact. The figure below shows an example in which the contact centroid lies outside of the DFN fracture so it is assigned the material number corresponding to outside of the fracture (in this case material 3). When you plot the joints and color by material number, it appears that the change dfn command didn’t work!

To see what is really happening, you can create user-defined scalars corresponding to each subcontact and color them according to the subcontact material number (see the FISH function included with the example below). This shows that the change dfn command did indeed work and that the subcontacts have been assigned the correct material number (2 in this case). You can also convince yourself that it is behaving correctly by contouring the joint properties.


Latest News
  • 3DEC 7 is officially released! Enhanced user interface with new automated block and zone generation tools, and new structural elements....
    Read More
  • Open Pit Dewatering: Dewater, Derisk, Deliver Learn more about developing an effective strategy for open pit dewatering and avoiding common pitfalls...
    Read More
  • Tutorial Series: Analyzing a Homogeneous Embankment Dam using FLAC 8.1 This is a three part tutorial series to calculate the total and effective stresses and...
    Read More

Upcoming Events
12 Oct
CANCELED -- Focused Seismic and Liquefaction Training 2020
... Read More
18 Oct
Geothermal Resources Council Annual Meeting & Expo
Advancing the global geothermal industry through transfer of robust research, knowledge and guidance.... Read More
2 Feb
ANALYSES OF EMBANKMENT DAMS AND SLOPES USING FLAC
This hands-on, virtual training course is 16 hours total, spread over four days in a 1.5-week period, and covers the analysis of embank... Read More