《Flac3D manual》Flac3D 手册（英文版）Fast Lagrangian Analysis of Continua in 3 Dimensions

User's guide 1.3.2 Optional Feature Four optional features(for dynamic analysis, thermal analysis, modeling creep-material behavior and writing user-defined constitutive models)are available as separate modules that can be included in FLAC3D at an additional cost per module. Also, a fifth optional feature, a hexahedral-meshing preprocessor(3DShop), is available as a separate program, at an additional cost Dynamic analysis can be performed with FLAC3D, using the optional dynamic-calculation module User-specified acceleration, velocity or stress waves can be input directly to the model, as either an exterior boundary condition or an interior excitation to the model. FLAC3D contains absorbing and free-field boundary conditions to simulate the effect of an infinite elastic medium surrounding the model. The dynamic calculation can be coupled to the groundwater flow model; the level of coupling, including dynamic pore-pressure generation(liquefaction), is discussed in Section 1.3.3 The dynamic analysis capability is described in Section 3 in Optional Features There is a thermal analysis option available as a special module in FLac3D. This model simulates the transient flux of heat in materials, and the subsequent development of thermally induced stresses The thermal model can be run independently, or coupled to the mechanical-stress calculation pore-pressure calculation, either static or dynamic.(The coupling interactions are described in Section 1.3.3. The thermal analysis capability is described in Section 1 in Optional Features There are eight optional material models available that simulate time-dependent(creep) material behavior(All creep models are described in Section 2 in Optional Features.) (1)the classical viscoelastic(Maxwell)model; (2) a Burgers substance viscoelastic me ()a two-component power law; (4)a reference creep formulation(the WIPP model)implemented for nuclear waste isolation studies (5)aBurger-creep viscoplastic model combining the Burger's model with the Mohr-Coulomb (6a power-law viscoplastic model combining the two-component power law and the mohr- Coulomb model (7)a WIPP-creep viscoplastic model combining the reference creep formulation with the Drucker-Prager plasticity model; and (8)a crushed-salt model that simulates both volumetric and deviatoric creep compactio s The hexahedral-meshing preprocessor 3DShop, enables the creation of complex meshes for FLAC3D. 3 DShop can substantially reduce model creation time. See Section 1 in the Hexahedral Meshing Preprocessor--3DShop volume for more information and a tutorial on 3DShop FLAC3D Version 3.1

1-6 User’s Guide 1.3.2 Optional Features Four optional features (for dynamic analysis, thermal analysis, modeling creep-material behavior, and writing user-defined constitutive models) are available as separate modules that can be included in FLAC3D at an additional cost per module. Also, a fifth optional feature, a hexahedral-meshing preprocessor (3DShop), is available as a separate program, at an additional cost.* Dynamic analysis can be performed with FLAC3D, using the optional dynamic-calculation module. User-specified acceleration, velocity or stress waves can be input directly to the model, as either an exterior boundary condition or an interior excitation to the model. FLAC3D contains absorbing and free-field boundary conditions to simulate the effect of an infinite elastic medium surrounding the model. The dynamic calculation can be coupled to the groundwater flow model; the level of coupling, including dynamic pore-pressure generation (liquefaction), is discussed in Section 1.3.3. The dynamic analysis capability is described in Section 3 in Optional Features. There is a thermal analysis option available as a special module in FLAC3D. This model simulates the transient flux of heat in materials, and the subsequent development of thermally induced stresses. The thermal model can be run independently, or coupled to the mechanical-stress calculation or pore-pressure calculation, either static or dynamic. (The coupling interactions are described in Section 1.3.3.) The thermal analysis capability is described in Section 1 in Optional Features. There are eight optional material models available that simulate time-dependent (creep) material behavior (All creep models are described in Section 2 in Optional Features.): (1) the classical viscoelastic (Maxwell) model; (2) a Burger’s substance viscoelastic model; (3) a two-component power law; (4) a reference creep formulation (the WIPP model) implemented for nuclear waste isolation studies; (5) a Burger-creep viscoplastic model combining the Burger’s model with the Mohr-Coulomb model; (6) a power-law viscoplastic model combining the two-component power law and the Mohr￾Coulomb model; (7) a WIPP-creep viscoplastic model combining the reference creep formulation with the Drucker-Prager plasticity model; and (8) a “crushed-salt” model that simulates both volumetric and deviatoric creep compaction. * The hexahedral-meshing preprocessor 3DShop, enables the creation of complex meshes for FLAC3D. 3DShop can substantially reduce model creation time. See Section 1 in the Hexahedral￾Meshing Preprocessor — 3DShop volume for more information and a tutorial on 3DShop. FLAC3D Version 3.1

INTRODUCTION 17 With this optional feature, user-defined constitutive models can be written in C++ and compiled as dll( dynamic link library)files that can be loaded whenever needed. Microsoft Visual C++ Version 8.0(Microsoft Visual Studio 2005) is used to compile the DLL files. The procedure to write new constitutive models and create dlls is described in Section 4 in Optional features 1.3.3 Modeling Physical Processes and Interactions The default calculation mode in FLAC 3D is for static mechanical analysis. Alternatively, a ground- water flow analysis or a heat-transfer analysis can be performed, independent of the mechanical alculation. Both the groundwater flow and thermal models may be coupled to the mechanical stress model and to each other. Because the full equations of motion are used in FLac 3d, the coupling mechanisms operate in dynamic analyses as well as static analyses The coupling mechanisms are divided into three types of interaction: mechanical and groundwater flow; mechanical and thermal and thermal and groundwater flow. the level of interaction modeled in FLAC3D for each type is described below Mechanical-Groundwater Flow Coupling Several types of fluid/solid interaction can be spec ified in FLAC3D. One type of interaction is consolidation, in which the slow dissipation of pore pressure causes displacements to occur in the solid(e.g, soil). Two mechanical effects are at work in this case: (1) the fuid in a zone reacts to mechanical volume changes by a change in the pore pressure; and(2) the pore-pressure change causes changes in the effective stress that affect the re- sponse of the solid(e. g, a reduction in effective stress may induce plastic yield). Coupling between fluid and solid due to deformable grains can also be specified FLAC3D can calculate pore-pressure effects, with or without pore-pressure dissipation, simply by setting the fow calculation on or off. Also, dynamic pore-pressure generation(e.g, related to liquefaction) can be modeled by accounting for irreversible volume strain in the constitutive model This is done with two different built-in constitutive models: the"Finn"model, and the Byrne model. Both models are provided with the dynamic option y default, porosity and permeability are assumed constant. However, these properties can be made a function of volumetric strain via a FISH function. As a consequence, two-way coupling of mechanical stress and groundwater flow can be modeled with FLAc3D. Other types of interaction, such as capillary, electrical or chemical forces between particles of a partially saturated material, are not modeled directly by FLAc3D. But some of the effects may be included by providing suitable FISH functions. Similarly, a FISH function may be used to vary the local fluid modulus as a function of other quantities such as pressure or time Thermal-Mechanical Coupling- The thermal-mechanical coupling in FLAC3D is one-way: tem- perature change may induce a mechanical stress change as a function of the thermal-expansion coefficient. Mechanical changes in the body, however, do not result in temperature change or changes to thermal properties. Additionally, mechanical properties can be made a function of temperature change, since FISH permits access to both temperatures and properties FLAC3D Version 3.1

INTRODUCTION 1-7 With this optional feature, user-defined constitutive models can be written in C++ and compiled as DLL (dynamic link library) files that can be loaded whenever needed. Microsoft Visual C++ Version 8.0 (Microsoft Visual Studio 2005) is used to compile the DLL files. The procedure to write new constitutive models and create DLLs is described in Section 4 in Optional Features. 1.3.3 Modeling Physical Processes and Interactions The default calculation mode in FLAC3D is for static mechanical analysis. Alternatively, a ground￾water flow analysis or a heat-transfer analysis can be performed, independent of the mechanical calculation. Both the groundwater flow and thermal models may be coupled to the mechanical stress model and to each other. Because the full equations of motion are used in FLAC3D, the coupling mechanisms operate in dynamic analyses as well as static analyses. The coupling mechanisms are divided into three types of interaction: mechanical and groundwater flow; mechanical and thermal; and thermal and groundwater flow. The level of interaction modeled in FLAC3D for each type is described below. Mechanical-Groundwater Flow Coupling — Several types of fluid/solid interaction can be spec￾ified in FLAC3D. One type of interaction is consolidation, in which the slow dissipation of pore pressure causes displacements to occur in the solid (e.g., soil). Two mechanical effects are at work in this case: (1) the fluid in a zone reacts to mechanical volume changes by a change in the pore pressure; and (2) the pore-pressure change causes changes in the effective stress that affect the re￾sponse of the solid (e.g., a reduction in effective stress may induce plastic yield). Coupling between fluid and solid due to deformable grains can also be specified. FLAC3D can calculate pore-pressure effects, with or without pore-pressure dissipation, simply by setting the flow calculation on or off. Also, dynamic pore-pressure generation (e.g., related to liquefaction) can be modeled by accounting for irreversible volume strain in the constitutive model. This is done with two different built-in constitutive models: the “Finn” model, and the “Byrne” model. Both models are provided with the dynamic option. By default, porosity and permeability are assumed constant. However, these properties can be made a function of volumetric strain via a FISH function. As a consequence, two-way coupling of mechanical stress and groundwater flow can be modeled with FLAC3D. Other types of interaction, such as capillary, electrical or chemical forces between particles of a partially saturated material, are not modeled directly by FLAC3D. But some of the effects may be included by providing suitable FISH functions. Similarly, a FISH function may be used to vary the local fluid modulus as a function of other quantities such as pressure or time. Thermal-Mechanical Coupling — The thermal-mechanical coupling in FLAC3D is one-way: tem￾perature change may induce a mechanical stress change as a function of the thermal-expansion coefficient. Mechanical changes in the body, however, do not result in temperature change or changes to thermal properties. Additionally, mechanical properties can be made a function of temperature change, since FISH permits access to both temperatures and properties. FLAC3D Version 3.1

I-8 User's guide Thermal-Groundwater Flow Coupling- The thermal calculation may be coupled to the ground water flow calculation by making pore pressures a function of temperature change. Volumetric strain can arise from thermal expansion of both the fluid and the grains within a saturated matrix Pore pressure change results from this volumetric strain, as well as from mechanical volumet- strain. Groundwater flow can also influence heat transfer: an advection model that takes the transport of heat by convection into account is provided. The advection model can also simulate temperature-dependent fuid density and thermal advection in the fluid As with mechanical properties, groundwater properties can be made a function of temperature change by accessing temperature and property values via FISH FLAC3D Version 3.1

1-8 User’s Guide Thermal-Groundwater Flow Coupling — The thermal calculation may be coupled to the ground￾water flow calculation by making pore pressures a function of temperature change. Volumetric strain can arise from thermal expansion of both the fluid and the grains within a saturated matrix. Pore pressure change results from this volumetric strain, as well as from mechanical volumet￾ric strain. Groundwater flow can also influence heat transfer; an advection model that takes the transport of heat by convection into account is provided. The advection model can also simulate temperature-dependent fluid density and thermal advection in the fluid. As with mechanical properties, groundwater properties can be made a function of temperature change by accessing temperature and property values via FISH. FLAC3D Version 3.1

INTRODUCTION 1. 4 Summary of Updates from Version 3.0 FLAC3D 3. 1 contains several improvements; the new features are summarized in the following sections. Existing data files created for Versions 3.0 and 2. 1 should still operate as before. FLAC3D 3. 1 will not be able to restore files saved by versions earlier than FLAc3D 2.1 1.4.1 Parallel processing on Multiprocessor Computers 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 processi 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. The number of processors used for the multithreaded calculations can also be specified manually by issuing the SEt processors n command in which n is the number of processors to be used 1. 4.2 64-Bit version 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 1.4.3 Embedded liner 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 esidual 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 diffe ent properties on each side of the wall. See Section 1.9 in Structural Elements for additional information and an example application of the embedded liner FLAC3D Version 3.1

INTRODUCTION 1-9 1.4 Summary of Updates from Version 3.0 FLAC3D 3.1 contains several improvements; the new features are summarized in the following sections. Existing data files created for Versions 3.0 and 2.1 should still operate as before. FLAC3D 3.1 will not be able to restore files saved by versions earlier than FLAC3D 2.1. 1.4.1 Parallel Processing on Multiprocessor Computers 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. The number of processors used for the multithreaded calculations can also be specified manually by issuing the SET processors n command, in which n is the number of processors to be used. 1.4.2 64-Bit Version 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. 1.4.3 Embedded Liner 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 differ￾ent properties on each side of the wall. See Section 1.9 in Structural Elements for additional information and an example application of the embedded liner. FLAC3D Version 3.1

1-10 User's guide 1. 4.4 Two-Dimensional Grid Extrusion Tool A special grid-generation tool is available in Version 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 GlIC )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 3D model for use in FLac3D 3. 1. The Flac 5.0 extrusion GlIC is dire accessible from a FLAC3D 3. 1 menu item(FILE/FLAC EXTRUDE) or a command( FLACEXTRU FLAC 5.0 needs to be installed, but a FLac 5.0 license is not necessary to access this feature. See Section 3. 2. 4 for a description and example applications of the grid-extrusion tool 1. 4.5 Nodal Mixed discretization A Nodal Mixed Discretization(NMD) technique for use with linear tetrahedra has been imple mented 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 zones 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 dditional constraint imposed on each zone by, for example, the classical incompressibility con- dition 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 discretize tion of the domain into hexahedral zones. The logic thus allows for the use of tetrahedral mesh generation capabilities existing today. The NMd technique is described in detail in Section 1.2.2 in Theory and Background. The technique is invoked by specifying the SET nmd on command (NMD is experimental at this stage 1.4.6 Built-in Help In addition to the complete set of PDF manuals that is provided with FLAC3D 3.1, the Com- mand 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 14.7 New Features in Fsa The following FISH variables have dded to FLAC3D 3. 1(see the FISH in FLAC3D volume for more details) z numoverlays returns number of overlays(, 1, or 2)in a zone z_ numtets returns the number of tetrahedra in a specified overlay FLAC3D Version 3.1

1 - 10 User’s Guide 1.4.4 Two-Dimensional Grid Extrusion Tool A special grid-generation tool is available in Version 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 3D model for use in FLAC3D 3.1. The FLAC5.0 extrusion GIICis 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. See Section 3.2.4 for a description and example applications of the grid-extrusion tool. 1.4.5 Nodal Mixed Discretization A Nodal Mixed Discretization (NMD) technique for use with linear tetrahedra has been imple￾mented 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 con￾dition 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 discretiza￾tion of the domain into hexahedral zones. The logic thus allows for the use of tetrahedral mesh generation capabilities existing today. The NMD technique is described in detail in Section 1.2.2 in Theory and Background. The technique is invoked by specifying the SET nmd on command. (NMD is experimental at this stage.) 1.4.6 Built-in Help In addition to the complete set of PDF manuals that is provided with FLAC3D 3.1, the Com￾mand 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. 1.4.7 New Features in FISH The following new FISH variables have been added to FLAC3D 3.1 (see the FISH in FLAC3D volume for more details): z numoverlays returns number of overlays (0, 1, or 2) in a zone z numtets returns the number of tetrahedra in a specified overlay FLAC3D Version 3.1