New in 3.1

In addition to the 32-bit version of FLAC3D 3.1, a 64-bit version is available (at no additional cost). FLAC3D 32-bit is capable of creating models up to 2 GB in size. FLAC3D 64-bit will allow a virtually unlimited model size (17 billion GB of addressable memory). FLAC3D 64-bit does not offer a computational speed increase over the 32-bit version, but does allow extremely large models to be created. FLAC3D 64-bit has features identical to those in the 32-bit version, and save files created by either version are compatible. The 64-bit version will only operate on a 64-bit processor computer running the Windows XP X64 operating system.

Mechanical calculations of the main grid are now multithreaded and take advantage of multiple processors (e.g., dual processors or a dual core processor). On a two dual-core processor system, FLAC3D would split the mechanical computations among four cores. Parallel processing is a standard feature of FLAC3D 3.1, and a speed increase of approximately 1.8 times has been noted on two-processor systems. Parallel processing also seamlessly integrates with user-defined models (UDMs). The mechanical calculations are automatically multithreaded when running FLAC3D 3.1 on a multiprocessor computer.

In addition to the complete set of PDF manuals that is provided with FLAC3D 3.1, the Command Reference, FISH in FLAC3D and Example Applications volumes are available as built-in, searchable help through the FLAC3D 3.1 help menu or the HELP command.

The SEL liner implementation in FLAC3D only provides for interaction with the grid on one side of the liner. The new embedded liner logic (SEL liner embedded) extends the single-sided liner interaction to two sides. Shear-directed frictional interaction occurs independently on both sides of the embedded liner, and compressive and tensile forces are calculated separately on both sides in the normal direction. The embedded liner supports the following independent properties on each side: normal coupling-spring tensile strength and stiffness, shear coupling-spring cohesion, residual cohesion, friction angle and stiffness.

An embedded liner allows more accurate modeling of problems such as retaining walls, where interaction is required between the main grid and both sides of the retaining wall, with different properties on each side of the wall.

A Nodal Mixed Discretization (NMD) technique for use with linear tetrahedra has been implemented in FLAC3D 3.1. NMD overcomes the over-stiff behavior observed by these zones during plastic flow, due to the volumetric constraint introduced by plasticity. In this technique, the zone’s volumetric behavior is averaged over the zones sharing its gridpoints. The effect of applying the NMD scheme is to increase the number of degrees of freedom per zone, thus accommodating the additional constraint imposed on each zone by, for example, the classical incompressibility condition for frictionless material. The advantage of the technique, compared to the standard mixed discretization scheme currently implemented in FLAC3D, is that it does not require a discretization of the domain into hexahedral zones. The logic thus allows for the use of tetrahedral mesh generation capabilities existing today.

Please note: the NMD technique is only partially validated at present. The technique is described in detail in the below-referenced PDF, available for download.

A special grid-generation tool is available inVersion 3.1 to create a three-dimensional FLAC3D mesh by extruding a two-dimensional FLAC grid. The grid-generation tool is a menu-driven graphical interface. A two-dimensional grid can be created directly within the tool, or a FLAC3D Version 5.0 data file can be loaded into the tool to create the extruded FLAC3D mesh. Two types of grid extrusions are available: a linear extrusion orthogonal to the two-dimensional grid plane, and an extrusion that revolves about an axis of revolution.

The powerful graphical user interface available with FLAC 5.0 (the GIIC ) can be used to construct a complicated 2D cross-section (e.g., a tunnel with excavation sequence geometry). This 2D tunnel can then be extruded into a 3Dmodel for use in FLAC3D 3.1. The FLAC5.0 extrusion GIIC is directly accessible from a FLAC3D 3.1 menu item (File/FLAC Extrude) or a command (FLACEXTRUDE). FLAC 5.0 needs to be installed, but a FLAC 5.0 license is not necessary to access this feature.