常用null, elastic, and mohr-coulomb.本构模型，对于elastic模型，通常只需要下列两个属性

以下是Mohr-Coulomb可塑性模型的必需属性：

体积模量和剪切模量，或杨氏模量和泊松比；

摩擦角和膨胀角；

凝聚

拉伸强度。

如果未分配这些属性中的任何一个，则默认情况下将其值设置为零。

为不同区域分配不同的模型：

model new

zone create brick size 10,10,10

; elastic in upper half of grid

zone cmodel assign elastic range position-z=5,10

zone property bulk 1.5e8 ...      ;体积模量        

shear 0.3e8 ...             ;剪切模量

range position-z=5,10

; mohr-coulomb in lower half

zone cmodel assign mohr-coulomb range position-z=0,5

zone property bulk 1.5e8 ...              

shear 0.6e8 ...              

friction 30 ...              ;摩擦角

cohesion 5e6 ...          ;凝聚力   

tension 8.66e6 ...        ;张力     

range position-z=0,5

命令行及解释

;1create a project

;2create geometry/zones

model new

zone create radial-brick ...

point 0 (0,0,0) point 1 (10,0,0)...

point 2 (0,10,0) point 3 (0,0,10)...

size 3,5,5,7 ...

ratio 1,1,1,1.5 ...

dim 1,4,2 fill group "exc"

model save "gemo"

model new

zone create radial-brick ...

            point 0 (0,0,0)  point 1 (10,0,0)   ...

            point 2 (0,10,0)  point 3 (0,0,10)  ...

            size 3 5 5 7                        ...

            rat 1 1 1 1.5                       ...

            dim 1 4 2 fill

zone create radial-brick ...

            point 0 (0,0,0)  point 1 (0,0,10)   ...

            point 2 (0,10,0)  point 3 (-10,0,0) ...

            size 5 5 3 7                        ...

            rat 1 1 1 1.5                       ...

            dim 2 4 1 fill

zone create radial-brick ...

            point 0 (0,0,0)  point 1 (-10,0,0)  ...

            point 2 (0,10,0)  point 3 (0,0,-10) ...

            size 3 5 5 7                        ...

            rat 1 1 1 1.5                       ...

            dim 1 4 2 fill

zone create radial-brick ...

            point 0 (0,0,0)  point 1 (0,0,-10)  ...

            point 2 (0,10,0)  point 3 (10,0,0)  ...

            size 5 5 3 7                        ...

            rat 1 1 1 1.5                       ...

            dim 2 4 1 fill

; There are other ways to achieve the same result shown above, because we can take advantage of planes of symmetry. Parts of the model can be reflected about specified planes to produce a larger model. 

model new

zone create radial-brick  ...

            point 0 (0,0,0)  point 1 (10,0,0)  ...

            point 2 (0,10,0)  point 3 (0,0,10)  ...

            size  3,5,5,7   ...

            ratio 1,1,1,1.5 ...

            dim 1 4 2 fill

zone reflect dip  0 dip-direction 90

zone reflect dip 90 dip-direction 90

;model new

;zone create brick size 6,8,8

;When building a FLAC3D model, it is a good practice to start with a grid that has fewer zones to perform simple test runs and make refinements to the grid. Then, increase the number of zones to improve the accuracy.In its simplest form, the zone create command can supply new coordinates to a grid. For example, assume that the actual coordinates of the trench model run from -10.0 to 10.0 in the x-direction, -10.0 to 10.0 in the y-direction, and -20.0 to 0.0 in the (vertical) z-direction. The next listing shows how this would be specified.

;model new

;zone create brick size 6,8,8 ...

;point 0 -10, -10, -20 ...

;point 1  10, -10, -20 ...

;point 2 -10,  10, -20 ...

;point 3 -10, -10,   0

;In the preceding example, point 0, point 1, point 2, and point 3 are keywords that denote four of the corners of a standard FLAC3D mesh

;model new

;zone create brick size 6,8,8 ...

;point 0 -10, -10, -20 ...

;point 1  10, -10, -20 ...

;point 2 -10,  10, -20 ...

;point 3 -10, -10,   0 ...

;point 4  10,  10, -20 ...

;point 5 -10,  10,  10 ...

;point 6  10, -10,   0 ...

;point 7  10,  10,  10

;3create model groups

;Make the Model pane active, if it isn't already (click "Model" tab). 

;Press the Auto Assign Face Groups button 

;In the ensuing dialog, check Ignore Existing Group Names and press Assign Groups. 

;In the lower center tab group, make the State Record pane active by clicking anywhere in the pane (if currently on top of the tab group) or on its tab (if currently "beneath" another pane).

;Select the line

;>>zone face skin slot-skin "Skin"

;Right-click and choose Copy as Data File.

;Make the tutorial data file active, set the cursor at the end of the file, and paste (Ctrl + V or Edit ‣ Paste).

;Create groups for each of the five excavation stages. Type (or copy-paste from below) the lines that create the five groups ("exc1" through "exc5") in the data file.

;At the end of the data file, type (or copy-paste from below) model save "groups". The commands from this step and step (6) that have been added to "tutorial.f3dat" should appear as below:

zone group "exc1" range position (0,  0,0) (1,0.8,2)

zone group "exc2" range position (0,0.8,0) (1,1.6,2)

zone group "exc3" range position (0,1.6,0) (1,2.4,2)

zone group "exc4" range position (0,2.4,0) (1,3.2,2)

zone group "exc5" range position (0,3.2,0) (1,4.0,2)

;Note that these commands could also have been generated interactively using range selection tools in the Model pane. This was not done here for brevity.

;Rerun the model to this point by pressing solve 

zone group "lower" range position-z 1 100

;This creates a group of zones named "lower". It is possible that after cycling, the zones that fall in that range z 1 100 will be different. The zones in the group "lower", however, will be the same.

zone cmodel assign elastic range group "lower"

;To experiment, open the "Rendering" item in "Attributes for Zone Face" and observe the effect of changing the settings it contains. 

;4,5,6Specifying Models, Boundaries, and Initial Conditions

; assign constitutive model, initial, and boundary conditions

zone cmodel assign mohr-coulomb

zone property density 1000 ...

              bulk 1e8 ...

              shear 3e8 ...

              friction 35 ...

              cohesion 1e3 ...

              tension 1e3 

zone face apply velocity-normal 0 range group "West"

zone face apply velocity-normal 0 range group "Bottom"

zone face apply velocity-normal 0 range group "North"

model gravity (0,10,0)

zone initialize-stresses ratio 0.5

zone face apply stress-normal 0 gradient (0,[-10*1000*0.5],0) ...

            range group "East" or "Top"

   ; use of inline FISH in preceding line illustrates 

   ; the derivation of the value needed (-5000)

model new

; Create zones

zone create radial-brick ...

        point 0 (0,0,0) point 1 (10,0,0) ...

        point 2 (0,10,0) point 3 (0,0,10) ...

        size 3,5,5,7 ...

        ratio 1,1,1,1.5 ...

        dim 1 4 2 fill group 'exc'

zone face skin

; Constitutive model and properties

zone cmodel assign mohr-coulomb

zone property bulk 1e8 shear 3e8 friction 35 ...

              cohesion 1e3 tension 1e3 density 1000

; Boundary conditions

zone face apply velocity-normal 0 range group 'West'

zone face apply velocity-normal 0 range group 'Bottom'

zone face apply velocity-normal 0 range group 'North'

zone face apply stress-normal 0 gradient (0,-5000,0) range group 'East'

zone face apply stress-normal 0 gradient (0,-5000,0) range group 'Top'

model gravity (0,10,0)

zone initialize-stresses ratio 0.5

;a constant, compressive xx-stress component of 10 MPa can be applied to a boundary located at x = 10 with the command

zone face apply stress-xx -10e6 range position-x 10

;Remember that compressive stresses are negative.

zone face apply stress-yy -20e6 gradient (0,0,20e5) ...

                range position-y 0 position-z 0 10

;use v fix s

zone face apply velocity-x 0 range position-x 0

;creates a roller boundary at which the boundary plane is fixed in the x-direction, but free to move in the y- and z-directions.A pinned boundary condition (i.e., constrained in the x-, y-, and z-directions) can be specified with the command

zone face apply velocity (0,0,0) range position-x 0

zone initialize stress xx -50e6 yy -40e6 zz -10e6

This assigns initial compressive ;stress components of σxx = −50e6 σyy = −40e6 σzz = −10e6(If the initial stress state is subjected to gravitational loading, this may be added via the model gravity command. For example,)

model gravity (0,-9.81,0)

;If gravitational loading is specified, the material mass density must also be initialized with the command zone initialize density.

zone initialize density

;7step to equilibrium

;Type or copy-paste the lines below into the "tutorial" data file.

model largestrain true 

model history mechanical ratio

;The history of the maximum unbalanced force may be recorded by adding a history with the command

model solve

model save "tr_eq"

;rerun->make Plot01 active->Press Build Plot button in the Control Panel, and double-click "History Chart"->In the "Attributes" control set, press the plus button  adjacent to the label "mechanical ratio limit"->In the attributes for the History item, open the "Y-Axis" group (press the arrow adjacent to the label) and check the "Log" box to set the y-axis of the plot to a logarithmic scale.

;Additionally, the history of selected variables (e.g., velocity or displacement at a gridpoint) may be recorded. The following commands are examples:

zone history velocity-x position (3,4,4)

;records x-velocity at location (x = 3, y = 4, z = 4), 

zone history velocity-z position (0,0,8)

; records z-displacement at location (x = 0, y = 0, z = 8).

;a intact example

model new

; Create zones

zone create brick size 6 8 8

zone face skin

; Assign constitutive model and properties

zone cmodel assign elastic

zone property bulk 1e8 shear 0.3e8

; Boundary Conditions

zone face apply velocity-normal 0 range group 'East' or 'West'

zone face apply velocity-normal 0 range group 'North' or 'South'

zone face apply velocity-normal 0 range group 'Bottom'

zone face apply stress-normal -1e6 range group 'Top'

; Histories

model history mechanical ratio

zone history velocity-x position (3,4,4)

zone history displacement-z position (0,0,8)

; Step 

model step 1500

;model solve(two ways)

;model solve ratio 1e-6

; If the zones were all of equal size, the unbalanced force would be nearly zero. However, with graded meshes, it is usually necessary to perform some stepping to bring the model to an initial equilibrium state.In an analysis, it is very important that the model be at equilibrium before alterations are made. 

;8after model:excavation

; monitor trench excavation

zone gridpoint initialize displacement (0,0,0)

zone history displacement-x position (1,.01,.01)

zone history displacement-z position (.01,.01,2)

; excavation step 1

zone cmodel assign null range group "exc1"

model step 1000

model save "exc1"

; excavation step 2

zone cmodel assign null range group "exc2"

model step 1000

model save "exc2"

; excavation step 3

zone cmodel assign null range group "exc3"

model step 1000

model save "exc3"

; excavation step 4

zone cmodel assign null range group "exc4"

model step 1000

model save "exc4"

; excavation step 5

zone cmodel assign null range group "exc5"

model step 1000

model save "exc5"

;rerun->Plot1 active

;FLAC3D allows model conditions to be changed at any point in the solution process. These changes may take the following forms

;excavation of material

; addition or deletion of gridpoint loads or stresses 

;change of material model or properties for any zone

; and fix or free velocities for any gridpoint.

;NOTE：If moduli (bulk or shear) are changed in a model that is in equilibrium, no immediate effect will be observed because FLAC3D uses tangent, rather than secant, moduli.

;9examine model:plotting

;select  Files->Add new plot->name it->Press the Build Plot button->select History Chart or Zone and press OK->In the "Attributes" section on the Control Panel

;10further alterations:support(Support is installed after the second excavation stage to stablize the trench and prevent the failure seen in the third excavation stage.)

; install cable support

model restore "exc2"

structure cable create ...

            by-ray (1.0,0.4,1.5) (1,0,0) 4 segments 4

structure cable create ...

            by-ray (1.0,0.4,0.5) (1,0,0) 4 segments 4

structure cable create ... 

            by-ray (1.0,1.2,1.5) (1,0,0) 4 segments 4

structure cable create ...

            by-ray (1.0,1.2,0.5) (1,0,0) 4 segments 4

structure cable property ...

            young 2e9 ...

            yield-tension 1e8 ...

            cross-sectional-area 1.0 ...

            grout-cohesion 1e10 ...

            grout-stiffness 2e9 ...

            grout-perimeter 1.0

zone cmodel assign null range group "exc3"

model step 1000

model save "cab3"

structure cable create ...

            by-ray (1.0,2.0,1.5) (1,0,0) 4 segments 4

structure cable create ...

            by-ray (1.0,2.0,0.5) (1,0,0) 4 segments 4

structure cable property ...

            young 2e9 ... 

            yield-tension 1e8 ...

            cross-sectional-area 1.0 ...

            grout-cohesion 1e10 ...

            grout-stiffness 2e9 ...

            grout-perimeter 1.0

zone cmodel assign null range group "exc4"

model step 1000

model save "cab4"

structure cable create ...

            by-ray (1.0,2.8,1.5) (1,0,0) 4 segments 4

structure cable create ...

            by-ray (1.0,2.8,0.5) (1,0,0) 4 segments 4

structure cable property ...

            young 2e9 ... 

            yield-tension 1e8 ...

            cross-sectional-area 1.0 ...

            grout-cohesion 1e10 ...

            grout-stiffness 2e9 ...

            grout-perimeter 1.0

zone cmodel assign null range group "exc5"

model step 1000

model save "cab5"

;Simpler Example(If we were to set up the model such that the entire trench is excavated at once, we might have a file that appears as below.)

model new

; Create zones

zone create radial-brick ...

                         point 0 (0,0,0) point 1 (10,0,0) ...

                         point 2 (0,10,0) point 3 (0,0,10) ...

                         size 3,5,5,7 ...

                         ratio 1,1,1,1.5 ...

                         dim 1 4 2 fill group 'exc'

zone face skin

; Assign constitutive model and properties

zone cmodel assign mohr-coulomb

zone property bulk 1e8 shear 3e8 friction 35 ...

              cohesion 1e3 tension 1e3 density 1000

; Bondary condition

zone face apply velocity-normal 0 range group 'West'

zone face apply velocity-normal 0 range group 'North'

zone face apply velocity-normal 0 range group 'Bottom'

zone face apply stress-normal 0 gradient (0,-5000,0) ...

                range group 'East' or 'Top'

; Initial conditions

model gravity (0,10,0)

zone initialize-stresses ratio 0.5

; Histories

zone history displacement-x position 1,0,0

; Excavation and setup

model largestrain on

zone relax excavate range group 'exc'

; ... and then calculate the response:

model step 1000

;11project finishing(File->Save Project or Tools->Bundle->Pack)