flac3d之Interface

3INTERFACES

3.1General Comments

There are several instances in geomechanics in which it is desirable to represent planes on which sliding or separation can occur—for example:

1.joint,fault or bedding planes in a geologic medium;

2.an interface between a foundation and the soil;

3.a contact plane between a bin or chute and the material that it contains;

4.a contact between two colliding objects;and

5.a planar“barrier”in space,which represents a?xed,non-deformable boundary

at an arbitrary position and orientation.

FLAC3D provides interfaces that are characterized by Coulomb sliding and/or tensile and shear bonding.Interfaces have the properties of friction,cohesion,dilation,normal and shear stiffnesses, tensile and shear bond strength.Although there is no restriction on the number of interfaces or the complexity of their intersections,it is generally not reasonable to model more than a few simple interfaces with FLAC3D because it is awkward to specify complicated interface geometry.The program3DEC(Itasca1998)is speci?cally designed to model many interacting bodies in three dimensions;it should be used instead of FLAC3D for the more complicated interface problems. Interfaces may also be used to join regions that have different zone sizes.In general,the ATTACH command should be used to join grids together.However,in some circumstances it may be more convenient to use an interface for this purpose.In this case,the interface is prevented from sliding or opening because it does not correspond to any physical entity.

3.2Formulation

FLAC 3D represents interfaces as collections of triangular elements (interface elements),each of which is de?ned by three nodes (interface nodes).Interface elements can be created at any location in space.Generally,interface elements are attached to a zone surface face;two triangular interface elements are de?ned for every quadrilateral zone face.Interface nodes are then created automatically at every interface element vertex.When another grid surface comes into contact with an interface element,the contact is detected at the interface node,and is characterized by normal and shear stiffnesses,and sliding properties.

Each interface element distributes its area to its nodes in a weighted fashion.Each interface node has an associated representative area.The entire interface is thus divided into active interface nodes representing the total area of the interface.Figure 3.1illustrates the relation between interface elements and interface nodes and the representative area associated with an individual node.element

interface

Figure 3.1Distribution of representative areas to interface nodes

It is important to note that interfaces are one-sided in FLAC 3D .(This differs from the formulation of two-sided interfaces in two-dimensional FLAC (Itasca 2000).)It may be helpful to think of FLAC 3D interfaces as “shrink-wrap”that is stretched over the desired surface,causing the surface to become sensitive to interpenetration with any other face with which it may come into contact.The fundamental contact relation is de?ned between the interface node and a zone surface face,also known as the target face .The normal direction of the interface force is determined by the orientation of the target face.

During each timestep,the absolute normal penetration and the relative shear velocity are calculated for each interface node and its contacting target face.Both of these values are then used by the interface constitutive model to calculate a normal force and a shear-force vector.The constitutive model is de?ned by a linear Coulomb shear-strength criterion that limits the shear force acting at an interface node,normal and shear stiffnesses,tensile and shear bond strengths,and a dilation angle that causes an increase in effective normal force on the target face after the shear-strength limit is reached.By default,pore pressure is used in the interface effective stress calculation.This option can be activated/deactivated using the command INTERFACE i effective=on/off.Figure3.2 illustrates the components of the constitutive model acting at interface node(P).

Figure3.2Components of the bonded interface constitutive model

The normal and shear forces that describe the elastic interface response are determined at calculation time(t+ t)using the following relations.

F(t+ t)

n

=k n u n A+σn A(3.1)

F(t+ t) si =F(t)si+k s u(t+(1/2) t)

si

A+σsi A

where F(t+ t)

n is the normal force at time(t+ t)[force];

F(t+ t)

si is the shear force vector at time(t+ t)[force];

u n is the absolute normal penetration of the interface node

into the target face[displacement];

u si is the incremental relative shear displacement vector

[displacement];

σn is the additional normal stress added due to interface stress

initialization[force/displacement];

k n is the normal stiffness[stress/displacement];

k s is the shear stiffness[stress/displacement];

σsi is the additional shear stress vector due to interface stress

initialization;and

A is the representative area associated with the interface node[length2].

The inelastic interface logic works in the following way:

(1)Bonded interface—The interface remains elastic if stresses remain below the bond

strengths:there is a shear bond strength as well as a tensile bond strength.The nor-

mal bond strength is set using the tension interface property keyword.The command

INTERFACE n prop sbratio=sbr sets the shear bond strength to sbr times the normal bond

strength.The default value of sbratio(if not given)is100.0.The bond breaks if either the

shear stress exceeds the shear strength,or the tensile effective normal stress exceeds the

normal strength.Note that giving sbratio alone does not cause a bond to be established;

the tensile bond strength must also be set.

(2)Slip while bonded—An intact bond,by default,prevents all yield behavior(slip and

separation).There is an optional property switch(bslip)that causes just separation

to be prevented if the bond is intact(but allows shear yield,under the control of the

friction and cohesion parameters,using abs(F n)as the normal force).The command to

allow/disallow slip for a bonded interface segment is

INTER n PROP bslip=on

bslip=off

The default state of bslip(if not given)is off.

(3)Coulomb sliding—A bond is either intact or broken.If it is broken,then the behavior

of the interface segment is determined by the friction and cohesion(and of course the

stiffnesses).This is the default behavior,if bond strengths are not set(zero).A broken

bond segment cannot take effective tension(which may occur under compressive normal

force,if the pore pressure is greater).The shear force is zero(for a non-bonded segment)

if the effective normal force is tensile or zero.

The Coulomb shear-strength criterion limits the shear force by the following relation.

F smax=cA+tanφ(F n?pA)(3.2)

where c is the cohesion[stress]along the interface;

φis the friction angle[degrees]of the interface surface;and

p is pore pressure(interpolated from the target face),provided the keyword

effective=off has not been issued for the interface.

If the criterion is satis?ed(i.e.,if|F s|≥F smax),then sliding is assumed to occur,and |F s|=F smax,with the direction of shear force preserved.

During sliding,shear displacement may cause an increase in the effective normal stress on the joint,according to the relation:

σn:=σn+|F s|o?F smax

Ak s tanψk n

(3.3)

whereψis the dilation angle[degrees]of the interface surface;and

|F s|o is the magnitude of shear force before the above correction is made.

On printout(PRINT interface n prop tens),the value of tension denotes if a bond is intact or broken (or not set)—non-zero or zero,respectively.

The normal and shear forces calculated at the interface nodes are distributed in equal and opposite directions to both the target face and the face to which the interface node is connected(the host face). Weighting functions are used to distribute the forces to the gridpoints on each face.The interface stiffnesses are added to the accumulated stiffnesses at gridpoints on both sides of the interface,in order to maintain numerical stability.

Interface contacts are detected only at interface nodes,and contact forces are transferred only at interface nodes.The stress state associated with a node is assumed to be uniformly distributed over the entire representative area of the node.Interface properties are associated with each node; properties may vary from node to node.

By default,the effect of pore pressure is included in the interface calculation by using effective stress as the basis for the slip condition.(The interface pore pressure is interpolated from the target face.)This applies either in CONFIG?uid mode,or if pore pressures are assigned with the WATER table or INITIAL pp command without specifying CONFIG?uid.The user can switch options for interface i by using the command INTERFACE i effective=on/off.By default,in the FLAC3D logic,?uid?ow—saturated or unsaturated—is carried across an interface,provided the interface keyword maxedge is not used for that particular interface.The permeable interface option can be deactivated/reactivated for interface i by using the command INTERFACE i perm=on/off.Note that if the keyword maxedge is used,and perm is on for a particular interface,a warning is issued to inform the user that this interface will be considered as impermeable to?uid?ow.(Note that, for?uid?ow calculation only,a mechanical model must be present.Also,the command CYCLE 0with SET mech on should be used to initialize the weighting factors used to transfer?uid?ow information across the interface.)No pressure drop normal to the joint and no in?uence of normal displacement on pore pressure are calculated.Also,?ow of?uid along the interface is not modeled.

3.3Creation of Interface Geometry

Interfaces are created with the INTERFACE command.For cases in which an interface is required between two separate grids in the model,the command INTERFACE i face range...should be used to attach an interface to one of the grid surfaces.This command generates interface elements for interface i along all surface zone faces with a center point that fall within a speci?ed range.Any surfaces on which an interface is to be created must be generated initially with some separation between the adjacent surfaces;it must be possible to specify an existing surface in order to create the interface elements.(Also,a gap must be speci?ed between the two grids because the grid generator will automatically merge surface gridpoints if they are created at the same location in space.)

By default,two interface elements are created for each zone face.The number of interface elements can be increased by using the command INTERFACE i maxedge v.*This causes all interface elements with edge lengths larger than v to subdivide into smaller elements until their lengths are smaller than v.This command can be used to increase the resolution and decrease arching of forces in portions of a model that have large contrasts in zone size across an interface.

The following rules should be followed when using interface elements in FLAC3D.

1.If a smaller surface area contacts a larger surface area(e.g.,a small block resting

on a large block),the interface should be attached to the smaller region.

2.If there is a difference in zone density between two adjacent grids,the interface

should be attached to the grid with the greater zone density(i.e.,the greater

number of zones within the same area).

3.The size of interface elements should always be equal to or smaller than the

target faces with which they will come into contact.If this is not the case,the

interface elements should be subdivided into smaller elements.

4.Interface elements should be limited to grid surfaces that will actually come

into contact with another grid.

A simple example illustrating the procedure for interface creation is provided in Example3.1.The example is a block specimen containing a single joint dipping at an angle of45?.

Example3.1Creating a model with a dipping joint

;Create Base

gen zone brick size333&

p0(0,0,0)p1(3,0,0)p2(0,3,0)p3(0,0,1.5)&

p4(3,3,0)p5(0,3,1.5)p6(3,0,4.5)p7(3,3,4.5)

group Base

*Note that if CONFIG?uid is invoked,and perm is on for a particular interface,specifying maxedge for that interface will automatically make it impermeable.Do not specify maxedge if?ow across the interface is desired.

;Create Top-1unit high for initial spacing

gen zone brick size333&

p0(0,0,2.5)p1(3,0,5.5)p2(0,3,2.5)p3(0,0,7)&

p4(3,3,5.5)p5(0,3,7)p6(3,0,7)p7(3,3,7)

group Top range group Base not

;

;Create interface elements on the top surface of the base

interface1face range plane norm(-1,0,1)origin(1.5,1.5,3)dist0.1

;

plot create view_int

plot add surface

plot add interface red

plot show

pause

;

;Lower top to complete geometry

ini z add-1.0range group Top

save int.sav

Figure3.3shows the grid before the interface is created.Two sub-grid groups are de?ned:a Base grid,and a Top grid.Figure3.4shows the model with the interface elements attached to the Base grid.Figure3.5shows the?nal geometry with the sub-grids moved together.A uniaxial compression test with this model is described later in Section3.4.3.

Figure3.3Initial geometry before creation of the interface

Figure3.4Interface elements added

Figure3.5Final geometry

3.4Choice of Material Properties

Assignment of material properties(particularly stiffnesses)to an interface depends on the way in which the interface is used.Three possibilities are common.The interface may be:

1.an arti?cial device to connect two sub-grids together;

2.a real interface that is stiff compared to the surrounding material,but which can

slip and perhaps open in response to the anticipated loading.(This case also

encompasses the situation in which stiffnesses are unknown or unimportant,

but where slip and/or separation will occur—e.g.,?ow of frictional material

in a bin);or

3.a real interface that is soft enough to in?uence the behavior of the system(e.g.,

a joint with soft clay?lling or a dyke containing heavily fractured material).

These cases are examined in detail.

3.4.1Interface Used to Join Two Sub-grids

If possible,sub-grids should be joined with the ATTACH command.It is more computationally-ef?cient to use ATTACH than INTERFACE to join sub-grids.See Section3.2.1.2in the User’s Guide, for a description of,and restrictions on,the ATTACH command.

Under some circumstances it may be necessary to use an interface to join two sub-grids.This type of interface is assigned high strength properties with the INTERFACE command,thus preventing any slip or separation.(This is the equivalent of a“glued”interface in FLAC.)Shear and normal stiffnesses must also be provided;values of friction and cohesion are not needed.It is tempting (particularly for people familiar with?nite element methods)to give a very high value for these stiffnesses to prevent movement on the interface.However,FLAC3D does“mass scaling”(see Section1.1.2.6)based on stiffnesses—the response(and solution convergence)will be very slow if very high stiffnesses are speci?ed.It is recommended that the lowest stiffness consistent with small interface deformation be used.A good rule-of-thumb is that k n and k s be set to ten times the equivalent stiffness of the stiffest neighboring zone.The apparent stiffness(expressed in stress-per-distance units)of a zone in the normal direction is

max K+4

3

G

z min

(3.4)

where K&G are the bulk and shear moduli,respectively;and

z min is the smallest width of an adjoining zone in the normal direction—see

Figure3.6.

The max[]notation indicates that the maximum value over all zones adjacent to the interface is to be used(e.g.,there may be several materials adjoining the interface).

Interface

Figure3.6Zone dimension used in stiffness calculation

To illustrate the approach,consider Figure3.7,in which two sub-grids of unequal zoning are joined by the commands in Example3.2and are loaded by a pressure on the left-hand part of the upper surface:

Example3.2Joining two sub-grids

gen zone brick size444p00,0,0p14,0,0p20,4,0p30,0,2

gen zone brick size884p00,0,3p14,0,3p20,4,3p30,0,5

inter1face range z 2.9,3.1

inter1prop kn300e9ks300e9tens1e10SBRATIO=1

ini z add-1.0range z 2.9,5.1

model elas

prop bulk8e9shear5e9

fix z range z-.1.1

fix x range x-.1.1

fix x range x 3.9 4.1

fix y range y-.1.1

fix y range y 3.9 4.1

apply szz-1e6range z 3.9 4.1x0,2y0,2

hist unbal

solve

save join.sav

The value of(K+4G/3)is15GPa,and the minimum zone size adjacent to the interface is 0.5m.Hence,we choose both shear stiffness and normal stiffness to be150×109/0.5—i.e., k n=k s=3×1011Pa/m.The resulting contours of z-displacement are shown in Figure3.8.

Compare this result to that for a single grid,shown in Figure3.7in the User’s Guide.This plot is at the same scale and contour intervals as Figure3.8.The two plots are almost identical,which indicates that the interface does not affect the behavior to any great extent.

The prescription given in Eq.(3.4)is reasonable if the materials on the two sides of the interface are similar,and variations of stiffness occur only in the lateral directions.However,if the material on one side of the interface is much stiffer than that on the other,then Eq.(3.4)should be applied to the softer side.In this case,the deformability of the whole system is dominated by the soft side;making the interface stiffness ten times the soft-side stiffness will ensure that the interface has minimal in?uence on system compliance.

Figure3.7Two unequal sub-grids joined by an interface

Figure3.8Vertical displacement contours—two joined grids

3.4.2Real Interface—Slip and Separation Only

In this case,we simply need to provide a means for one sub-grid to slide and/or open relative to another sub-grid.The friction(and perhaps cohesion,dilation,and tensile strength)is important, but the elastic stiffness is not.The approach of Section3.4.1is used here to determine k n and k s. However,the other material properties are given real values(see Section3.4.3for advice on choice of properties).

As an example,we can allow slip in a bin-?ow problem,as shown in Figure3.9,corresponding to the data?le in Example3.3.The bond strengths are not set(i.e.,they default to zero);the interface stiffnesses are set to approximately ten times the equivalent stiffness of the neighboring zones.

Figure3.9Flow of frictional material in a“bin”

Example3.3Slip in a bin-?ow problem

;Create Material Zones

gen zone brick size555&

p0(0,0,0)p1(3,0,0)p2(0,3,0)p3(0,0,5)&

p4(3,3,0)p5(0,5,5)p6(5,0,5)p7(5,5,5) gen zone brick size555p0(0,0,5)edge 5.0

group Material

;Create Bin Zones

gen zone brick size155&

p0(4,1,0)p1add(3,0,0)p2add(0,3,0)&

p3add(2,0,5)p4add(3,6,0)p5add(2,5,5)&

p6add(3,0,5)p7add(3,6,5)

gen zone brick size155&

p0(6,1,5)p1add(1,0,0)p2add(0,5,0)&

p3add(0,0,5)p4add(1,6,0)p5add(0,5,5)&

p6add(1,0,5)p7add(1,6,5)

gen zone brick size515&

p0(1,4,0)p1add(3,0,0)p2add(0,3,0)&

p3add(0,2,5)p4add(6,3,0)p5add(0,3,5)&

p6add(5,2,5)p7add(6,3,5)

gen zone brick size515&

p0(1,6,5)p1add(5,0,0)p2add(0,1,0)&

p3add(0,0,5)p4add(6,1,0)p5add(0,1,5)&

p6add(5,0,5)p7add(6,1,5)

group Bin range group Material not

;Create named range synonyms

range name=Bin group Bin

range name=Material group Material

;Assign models to groups

model mohr range Material

model elas range Bin

;Create interface elements

int1face ran plane ori(4,0,0)nor(-5,0,2)dist0.01z(0,5)y(1,6) int2face ran plane ori(0,4,0)nor(0,-5,2)dist0.01z(0,5)x(1,6) int1face ran x 5.9 6.1y16z510

int2face ran x16y 5.9 6.1z510

int1maxedge0.55

int2maxedge0.55

;Move bin toward material

ini x add-1.0range Bin

ini y add-1.0range Bin

;Assign properties

prop shear1e8bulk2e8fric30range Material

prop shear1e8bulk2e8range Bin

ini den2000

int1prop ks2e9kn2e9fric15

int2prop ks2e9kn2e9fric15

;Assign Boundary Conditions

fix x range x-0.10.1any x 5.9 6.1any

fix y range y-0.10.1any y 5.9 6.1any

fix z range z-0.10.1Bin

;Monitor histories

hist unbal

hist gp zdisp(6,6,10)

hist gp zdisp(0,0,10)

hist gp zdisp(0,0,0)

;Settings

set large

set grav0,0,-10

;Cycling

step4000

save bin.sav

3.4.3All Properties Have Physical Signi?cance

In this case,properties should be derived from tests on real joints*(suitably scaled to account for size effect),or from published data on materials similar to the material being modeled.However, the comments of Section3.4.1also apply here with respect to the maximum stiffnesses that are reasonable to use.If the physical normal and shear stiffnesses are less than ten times the equivalent stiffness of adjacent zones,then there is no problem in using physical values.If the ratio is much more than ten,the solution time will be signi?cantly longer than for the case in which the ratio is limited to ten,without much change in the behavior of the system.Serious consideration should be given to reducing supplied values of normal and shear stiffnesses to improve solution ef?ciency. There may also be problems with interpenetration if the normal stiffness,k n,is very low.A rough estimate should be made of the joint normal displacement that would result from the application of typical stresses in the system(u=σ/k n).This displacement should be small compared to a typical zone size.If it is greater than,say,10%of an adjacent zone size,then there is either an error in one of the numbers,or the stiffness should be increased if calculations are to be done in large-strain mode.

Joint properties are conventionally derived from laboratory testing(e.g.,triaxial and direct shear tests).These tests can supply physical properties for joint friction angle,cohesion,dilation angle, and tensile strength,as well as joint normal and shear stiffnesses.The joint cohesion and friction angle correspond to the parameters in the Coulomb strength criterion?described in Section3.2. Values for normal and shear stiffnesses for rock joints typically can range from roughly10to100 MPa/m for joints with soft clay in-?lling,to over100GPa/m for tight joints in granite and basalt. Published data on stiffness properties for rock joints are limited;summaries of data can be found in Kulhawy(1975),Rosso(1976),and Bandis et al.(1983).

Approximate stiffness values can be back-calculated from information on the deformability and joint structure in the jointed rock mass and the deformability of the intact rock.If the jointed rock mass is assumed to have the same deformational response as an equivalent elastic continuum,then relations can be derived between jointed rock properties and equivalent continuum properties. For uniaxial loading of rock containing a single set of uniformly spaced joints oriented normal to the direction of loading,the following relation applies.

1

=1

r +1

n

(3.5)

*“Joint”is used here as a generic term.

?The Coulomb yield surface provides a reasonable approximation for joint strength for most engi-neering calculations.More complex joint models are available which include,for example,effects of continuous yielding and displacement weakening.For analysis with other joint models,the user is referred to UDEC(Itasca1996).

or

k n=

E E r

s(E r?E)

(3.6)

where E=rock mass Young’s modulus;

E r=intact rock Young’s modulus;

k n=joint normal stiffness;and

s=joint spacing.

A similar expression can be derived for joint shear stiffness:

k s=

G G r

s(G r?G)

(3.7)

where G=rock mass shear modulus;

G r=intact rock shear modulus;and

k s=joint shear stiffness.

The equivalent continuum assumption,when extended to three orthogonal joint sets,produces the following relations:

E i=

1

r

+1

i ni

?1

(i=1,2,3)(3.8)

G ij=

1

G r

+1

s i k si

+1

s j k sj

?1

(i,j=1,2,3)(3.9)

Several expressions have been derived for two-and three-dimensional characterizations and multiple joint sets.References for these derivations can be found in Singh(1973),Gerrard(1982(a)and (b)),and Fossum(1985).

Published strength properties for joints are more readily available than stiffness properties.Sum-maries can be found,for example,in Jaeger and Cook(1979),Kulhawy(1975),and Barton(1976). Friction angles can vary from less than10?for smooth joints in weak rock,such as tuff,to over 50?for rough joints in hard rock,such as granite.Joint cohesion can range from zero to values approaching the compressive strength of the surrounding rock.

It is important to recognize that joint properties measured in the laboratory typically are not rep-resentative of those for real joints in the?eld.Scale dependence of joint properties is a major question in rock mechanics.Often,the only way to guide the choice of appropriate parameters is by comparison to similar joint properties derived from?eld tests.However,?eld test observations are extremely limited.Some results are reported by Kulhawy(1975).

The following example illustrates an application of the interface logic to simulate the physical response of a rock joint subjected to normal and shear loading.The model represents a direct shear test,which consists of a single horizontal joint that is?rst subjected to a normal con?ning stress, and then to a unidirectional shear displacement.Figure3.10shows the model.

Figure3.10Direct shear test model

First,a normal stress of10MPa is applied that is representative of the con?ning stress acting on the joint.A horizontal velocity is then applied to the top sub-grid to produce a shear displacement along the interface.For demonstration purposes,we only apply a small shear displacement of less than2mm to this model.

The average normal and shear stresses,and normal and shear displacements along the joint,are measured with a FISH function.With this information we can determine the shear strength and dilation that are produced.The data?le for this test is contained in Example3.4.

Example3.4Direct shear test

title

Direct shear test

gen zone brick size12110p0406p11606p2416p34011 gen zone brick size20110p12000p2010p3005

range name bot z05

range name top z611

interface1face range z5

int1prop ks4e4kn4e4fric30dil6;tension1e10bslip=on

ini z add-1.0range top

;plo surf lorange interface white axes black

model e

prop bulk45e3sh30e3

fix x y z range z0

fix x range x0

fix x range x20

apply nstress-10range z10

step0

plot contour szz interface white axes black

solve

save dsta.sav

ini xvel5e-7range top

fix xvel range top

def ini_jdisp

valnd=0.0

count=0.0

p_in=i_node_head(i_head)

loop while p_in#null

if in_ztarget(p_in)#null then

valnd=valnd+in_pen(p_in)

count=count+ 1.0

end_if

p_in=in_next(p_in)

end_loop

njdisp0=valnd/count

end

ini_jdisp

def sstav

valns=0.0

valss=0.0

valsd=0.0

valnd=0.0

count=0.0

p_in=i_node_head(i_head)

loop while p_in#null

if in_ztarget(p_in)#null then

valns=valns+in_nstr(p_in)*in_area(p_in)

valss=valss+in_sstr(p_in,1)*in_area(p_in)

valsd=valsd+in_sdisp(p_in,1)

valnd=valnd+in_pen(p_in)

count=count+ 1.0

end_if

p_in=in_next(p_in)

end_loop

sstav=valss/(12.0*1.0)

nstav=valns/(12.0*1.0)

sjdisp=valsd/count

njdisp=valnd/count-njdisp0

end

hist ns1

hist sstav nstav sjdisp njdisp

ini xdis0ydis0zdis0

step2500

save dst.sav

plot his-1vs-3

pause

plot his-4vs-3

pause

ret

The average shear stress versus shear displacement along the joint is plotted in Figure3.11,and the average normal displacement versus shear displacement is plotted in Figure3.12.These plots indicate that joint slip occurs for the prescribed properties and conditions.The loading slope in Figure3.11is initially linear and then becomes nonlinear as interface nodes begin to fail until a peak shear strength of approximately5.8MPa is reached.As indicated in Figure3.12,the joint begins to dilate when the interface nodes begin to fail in shear.

Figure3.11Average shear stress versus shear displacement

Figure3.12Average normal displacement versus shear displacement

FLAC3D基础知识介绍

FLAC 3D 基础知识介绍 一、概述 FLAC（Fast Lagrangian Analysis of Continua ）由美国Itasca 公司开发的。目前，FLAC 有二维和三维计算程序两个版本，二维计算程序V3.0 以前的为DOS 版本，V2.5 版本仅仅能够使用计算机的基本内存64K），所以，程序求解的最大结点数仅限于2000个以内。1995 年，FLAC2D 已升级为V3.3 的版本，其程序能够使用护展内存。因此，大大发护展了计算规模。FLAC3D是一个三维有限差分程序，目前已发展到V3.0 版本。 FLAC3D的输入和一般的数值分析程序不同，它可以用交互的方式，从键盘输入各种命令，也可以写成命令（集）文件，类似于批处理，由文件来驱动。因此，采用FLAC程序进行计算，必须了解各种命令关键词的功能，然后，按照计算顺序，将命令按先后，依次排列，形成可以完成一定计算任务的命令文件。 FLAC3D是二维的有限差分程序FLAC2D的护展，能够进行土质、岩石和其它材料的三维结构受力特性模拟和塑性流动分析。调整三维网格中的多面体单元来拟合实际的结构。单元材料可采用线性或非线性本构模型，在外力作用下，当材料发生屈服流动后，网格能够相应发生变形和移动（大变形模式）。FLAC3D 采用的显式拉格朗日算法和混合-离散分区技术，能够非常准确的模拟材料的塑性破坏和流动。由于无须形成刚度矩阵，因此，基于较小内存空间就能够求解大范围 的三维问题。

三维快速拉格朗日法是一种基于三维显式有限差分法的数值分析 方法，它可以模拟岩土或其他材料的三维力学行为。三维快速拉格朗日分析将计算区域划分为若干四面体单元，每个单元在给定的边界条件下遵循指定的线性或非线性本构关系，如果单元应力使得材料屈服或产生塑性流动，则单元网格可以随着材料的变形而变形，这就是所 谓的拉格朗日算法，这种算法非常适合于模拟大变形问题。三维快速 拉格朗日分析采用了显式有限差分格式来求解场的控制微分方程，并应用了混合单元离散模型，可以准确地模拟材料的屈服、塑性流动、软化直至大变形，尤其在材料的弹塑性分析、大变形分析以及模拟施工过程等领域有其独到的优点。 FLAC-3D(Three Dimensional Fast Lagrangian Analysis of Continua)是美国Itasca Consulting Goup lnc 开发的三维快速拉格朗日分析程序，该程序能较好地模拟地质材料在达到强度极限或屈服极限时发生的破坏或塑性流动的力学行为，特别适用于分析渐进破坏和失稳以及模拟大变形。它包含10种弹塑性材料本构模型，有静力、动力、蠕变、渗流、温度五种计算模式，各种模式间可以互相藕合，可以模拟多种结构形式，如岩体、土体或其他材料实体，梁、锚元、桩、壳以及人工结构如支护、衬砌、锚索、岩栓、土工织物、摩擦桩、板桩、界面单元等，可以模拟复杂的岩土工程或力学问题。 FLAC3D采用ANSI C++语言编写的。 二、FLAC3D的优点与不足 FLAC3D有以下几个优点: 1对模拟塑性破坏和塑性流动采用的是混合离散法。这种方

Flac3D命令--完整经典版

实例分析命令： 1. X ，Y ，Z 旋转 Shift+ X ，Y ，Z 反向旋转 Gen zone ……；model ……；prop ……（材料参数）；set grav 0,0,-9.81（重力加速度） plot add block group red yellow 把在group 中的部分染成红色和黄色 plot add axes black 坐标轴线为黑色；print zone stress% K 单元应力结果输出 ini dens 2000 ran z a b （设置初始密度，有时不同层密度不同）；ini ……（设置初始条件）；fix ……（固定界面） set plot jpg ；set plot quality 100 ；plot hard file 1.jpg 图像输出（格式、像素、名称） plot set magf 1.0视图的放大倍数为1.0；plo con szz z 方向应力云图 2. ini z add -1 range group one 群one 的所有单元，在z 方向上向下移动1m ；然后合并 命令 gen merge 1e-5 range z 0此命令是接触面单元合并成一个整体，1e-5是容差 3. (基坑开挖步骤)：Step 1: create initial model state （建立初始模型）Step 2: excavate trench （开挖隧道） 4. group Top range group Base not 定义（群组Base 以外的为）群组Top 5. plot blo gro 使得各个群组不同颜色显示 6. （两个部分间设置界面；切割法）：gen separate Top 使两部分的接触网格分离 为两部分；interface 1 wrap Base Top 在（Base 和Top ）这两部分之间添加接触单元；plot create view_int 显示，并创建标题view_int ；plot add surface 显示表面；plot add interface red 界面颜色红色 7. （简单的定义函数及运行函数）new ；def setup 定义函数setup ；numy = 8定义常 量numy 为8；depth = 10.0 定义depth 为10；end 结束对函数的定义；setup 运行函数setup 8. （隧道生成）上部圆形放射性圆柱及下部块体单元体的建立，然后镜像。 9. 模拟模型的材料问题时为什么要去定义某个方向上的初始速度？— 10. 渐变应力施加：apply nstress -1e6 gradient 0,0,1e5 range z 3.464,0 plane dip 60 dd 270 origin .1 0 0；施加法向应力：apply nstress -1e6 range plane dip 60 dd 270 origin .1 0 0 11. d ip dd 确定平面位置使用：（纠结） 12. p rint gp position range id=14647 输出节点坐标 13. a pply sxx -10e6 gradient 0 , 0, 1e5 range z -100 , 0在这个求解方程中，z 为变量，所以xx σ为：65=-1010+10xx z σ?? ；原点（0,0,0） 14. f ree x range x -.1 .1 z 6.9 10.1放松x=0 平面上，z=7，10 这一部分在x 方向的约 束（可以在此处产生破坏） 15. 体积模量K 和剪切模量G 与杨氏模量及泊松比v 之间的转换关系如下： =3(1-2v)E K G=2(1+v) E 16. 一般而言，大多数问题可以采用FLAC 3D 默认的收敛标准（或称相对收敛标准），即当体 系最大不平衡力与典型内力的比率R 小于定值10-5；（也可由用户自定义该值，命令：

FLAC3D基础知识介绍

FLAC 3D基础知识介绍 一、概述 FLAC(Fast Lagrangian Analysis of Continua)由美国Itasca公司开发的。目前,FLAC有二维与三维计算程序两个版本,二维计算程序V3、0以前的为DOS版本,V2、5版本仅仅能够使用计算机的基本内存64K),所以,程序求解的最大结点数仅限于2000个以内。1995年,FLAC2D已升级为V3、3的版本,其程序能够使用护展内存。因此,大大发护展了计算规模。FLAC3D就是一个三维有限差分程序,目前已发展到V3、0版本。 FLAC3D的输入与一般的数值分析程序不同,它可以用交互的方式,从键盘输入各种命令,也可以写成命令(集)文件,类似于批处理,由文件来驱动。因此,采用FLAC程序进行计算,必须了解各种命令关键词的功能,然后,按照计算顺序,将命令按先后,依次排列,形成可以完成一定计算任务的命令文件。 FLAC3D就是二维的有限差分程序FLAC2D的护展,能够进行土质、岩石与其它材料的三维结构受力特性模拟与塑性流动分析。调整三维网格中的多面体单元来拟合实际的结构。单元材料可采用线性或非线性本构模型,在外力作用下,当材料发生屈服流动后,网格能够相应发生变形与移动(大变形模式)。FLAC3D采用的显式拉格朗日算法与混合-离散分区技术,能够非常准确的模拟材料的塑性破坏与流动。由于无须形成刚度矩阵,因此,基于较小内存空间就能够求解大范围的

三维问题。 三维快速拉格朗日法就是一种基于三维显式有限差分法的数值分析方法,它可以模拟岩土或其她材料的三维力学行为。三维快速拉格朗日分析将计算区域划分为若干四面体单元,每个单元在给定的边界条件下遵循指定的线性或非线性本构关系,如果单元应力使得材料屈服或产生塑性流动,则单元网格可以随着材料的变形而变形,这就就是所谓的拉格朗日算法,这种算法非常适合于模拟大变形问题。三维快速拉格朗日分析采用了显式有限差分格式来求解场的控制微分方程,并应用了混合单元离散模型,可以准确地模拟材料的屈服、塑性流动、软化直至大变形,尤其在材料的弹塑性分析、大变形分析以及模拟施工过程等领域有其独到的优点。 FLAC-3D(Three Dimensional Fast Lagrangian Analysis of Continua)就是美国Itasca Consulting Goup lnc开发的三维快速拉格朗日分析程序,该程序能较好地模拟地质材料在达到强度极限或屈服极限时发生的破坏或塑性流动的力学行为,特别适用于分析渐进破坏与失稳以及模拟大变形。它包含10种弹塑性材料本构模型,有静力、动力、蠕变、渗流、温度五种计算模式,各种模式间可以互相藕合,可以模拟多种结构形式,如岩体、土体或其她材料实体,梁、锚元、桩、壳以及人工结构如支护、衬砌、锚索、岩栓、土工织物、摩擦桩、板桩、界面单元等,可以模拟复杂的岩土工程或力学问题。 FLAC3D采用ANSI C++语言编写的。 二、FLAC3D的优点与不足

[实用参考]Flac3d-5.0常用命令集锦.doc

建模 1、调用文件： ①文件与工程在同一个文件夹，只写文件名即可：Ifthecalledfileislocatedinthesamefolderasthe FLAC3D projectfile,thenonlyt hefilenameneed beenteredwiththe CALL command. ②不在同一个文件夹，全路径：Otherwise,thefilemaybecalledbyspecifyingitscompletepath(e.g.,c:\myfol der\file.dat). Undo;撤销上一条命令 2、创建旋转缩放视图 3、建模命令 modelmechmohr;莫尔库伦模型 modelmechelastic;弹性模型 setgrav0,0,-9.81;重力加速度negative z-direction.（垂直向下！常用的） 下下面面这这代代码码，，是是沿沿着着--y y方方向向的的重重力力加加速速度度，，注注意意区区别别！！！！！！！！ genzonebricksize6,8,8p0-10,-10,-20...;省略号表示写不下后面继续 p110,-10,-20... p2-10,10,-20... p3-10,-10,0 plotzone

genzonebricksize6,8,8p0-10,-10,-20...;不规则六面体 p110,-10,-20p2-10,10,-20... p3-10,-10,0p410,10,-20... p5-10,10,10p610,-10,0... p710,10,10 plotcurrentplotPlot01 plotclear plotzone Undo;撤销命令 setlogfile127G1001.tGt setlogontruncate setlogoff listzoneprinrangeG01y01z01;显示指定范围内各单元的主应力，结果如下 Hist命令： ①命令编号按顺序从1开始：eachhistoryisnumberedsequentiallyfrom1asitisenteredviathe HISTORY co mmand. ②查找显示所有的his命令：ReturntotheFlac3D>promptandtype listhist foralistingofthehistoriesandtheircorrespondingnumbers. histnstep5;每5步记录1次。默认是10步记录1次

FLAC3D基础命令流解释

;模型镜像 gen zone radcylinder size 25 1 25 25 gen zone reflect normal -1 0 0 origin x y z(面上一点）;沿X轴镜像,通过对称平面法线向量确定对称面 gen zone reflect normal 0 0 -1 ;沿z轴镜像 ;绘图控制 pl contour szz outline on ;在模型中显示位移-应变曲线 hist gp ydisp 0,0,0 hist zone syy 0,1,0 hist zone syy 1,1,0 pl his -2 -3 vs 1 ;在plot hist m vs n的形式里,m代表y轴,n代表x轴(不管m,n的正负); "-"表示对其值作"mirror" ;对模型进行压缩实验的方法 ;即在模型两侧施加相反方向的速度 ini yvel 1e-7 range y -.1 .1 ini yvel -1e-7 range y 1.9 2.1 ;修改模型的坐标值 ini x add -100 y add -100 z add -100 ;显示云图的同时也显示模型网格轮廓 plot add cont disp outline on ;gradient更精确 ;输入角度、弧度方法 pi=π，90°为90.0*degrad def set_vals ptA = 25.0 * sin(pi/2);ptA=25.0 ptB = 25.0 * cos( 60.0*degrad );ptB=12.5 ptC=pi;ptC=3.1415926 end set_vals print ptA ptB ptC ;施加结构单元方法 sel shell id=5 range cylinder end1=(0.0, 0.0,0.0) & end2=(0.0,25.0,0.0) radius=24.5 not plot add sel geom black black cid on scale=0.03 sel node init zpos add -25.0 ;如何显示某一平面 plot create name_plane plot set plane origin 3 4 0 normal 1 0 0 plot add cont disp plane behind shade on plot add sel geom black plot add axes red

Flac3D中文流体计算

Flac3D 中文手册 FLAC3D的计算模式中是否需要做孔压分析取决于是否采用config fluid命令。 1 无渗流模式（不使用config fluid） 即使不使用命令config fluid，仍然可以在节点上施加孔压。这种模式下，孔压将保持为常量。如果采用塑性本构模型的话，材料的破坏将由有效应力状态来控制。 节点上的孔压分布可由initial pp命令或water table命令来设定。如果采用water table命令，由程序自动计算水位线以下的静水孔压分布。此时，必须施加流体密度（water density）和重力（set gravity）。流体密度值和水位位置可以用命令print water显示。如果水位线是由face关键字来定义的，则可用命令plot water命令显示水位。 这两种情况，单元的孔压都由节点孔压值平均求出，并在本构模型计算中用作有效应力。这种计算模式下，体积力中不反映流体的出现：用户必须根据水位线以上或以下相应地指定干密度和湿密度。使用命令print gp pp和priint zone pp可分别得到节点或单元孔压。plot contour pp命令可绘出节点孔压云图。 2 渗流模式（使用config fluid） 如果使用命令config fluid，则可进行瞬时渗流分析，孔压改变和潜水面的改变都可能出现。在config fluid模式下，有效应力计算（静态孔压分布）和非排水计算均被执行。除此之外，还可进行全耦合

分析，这种情况下，孔压改变将使固体产生变形，同时体积应变反过来影响孔压的变化。 如果采用渗流模式，单元孔压仍由节点孔压平均求出。但这种模式，用户只能指定干密度（不论是水位以上还是以下），因为FLAC3D将流体的影响考虑到了体积力的计算中。 采用渗流模式时，渗流模型必须施加到单元上，使用命令model fl_isotropic模拟各向同性渗流，model fl_anisotropic模拟各向异性渗流，model fl_null模拟非渗透物质。注意，力学模型为空的单元并不代表渗流模型为空。 流体性质（参数）可施加到单元或节点上。各向同性渗透率、孔隙率、比奥系数和非排水热系数等单元流体性质由命令property施加。 对于各向同性渗流，渗透率通过perm关键字赋予。对各向异性渗流，渗透率的3个主值采用关键字k1,k2,k3赋予，主方向由关键字fdip,fdd,frot确定。渗透率的主方向服从右手系统。fdip和fdd分别为k1和k2确定的平面的倾向和倾角。frot为k1轴和倾角矢量的旋转角。如果不特别指定，比奥系数默认为1，孔隙率默认为0.5。节点的渗流性质由命令initial指定。这些性质包括流体重度、流体体积模量、比奥模量、流体抗拉强度和饱和度。每种性质在空间上都可以变化。流体重度也可以用water命令给出。 在渗流模式里，有必要知道可压缩性被定义在以下两种参数中：（1）比奥系数和比奥模量；（2）流体体积模量和孔隙率。第一种

flac3d常用命令

1、最先需要掌握的命令有哪些？ 答：需要掌握gen, ini, app, plo, solve等建模、初始条件、边界条件、后处理和求解的命令。 2、怎样输出模型的后处理图？ 答：File/Print type/Jpg file，然后选择File/Print，将保存格式选择为jpe文件。 3、怎样调用一个文件？ 答：File/call或者call命令 4、如何施加面力？ 答：app nstress 5、如何调整视图的大小、角度？ 答：综合使用x, y, z, m, Shift键，配合使用Ctrl+R，Ctrl+Z等快捷键。 6、如何进行边界约束？ 答：fix x ran （约束的是速度，在初始情况下约束等效于位移约束）。 7、如何知道每个单元的ID？ 答：用鼠标双击单元的表面，可以知道单元的ID和坐标。 8、如何进行切片？ 答：plo set plane ori (点坐标) norm (法向矢量) plo con sz plane (显示z方向应力的切片) 9、如何保存计算结果？ 答：save +文件名 10、如何调用已保存的结果？ 答：rest +文件名；或者File / Restor 11、如何暂停计算？ 答：Esc 12、如何在程序中进行暂停，并可恢复计算？ 答：在命令中加入pause命令，用continue进行继续。 在我们分步求解中想得到某一个过程中的结果，不用等到全求完，还可以在分布求解错误的时候就进行改正，而不是等到结果出来。 13、如何跳过某个计算步？ 答：在计算中按空格键跳过本次计算，自动进入下一步 14、Fish是什么东西？Fish是否一定要学？

答：是FLAC3D的内置语言，可以用来进行参数化模型、完成命令本身不能进行的功能。Fish可以不用学，需要的时候查Mannual获得需要的变量就可以了。 15、FLAC3D允许的命令文件格式有哪些？ 答：无所谓，只要是文本文件，什么后缀都可以。 16、如何调用一些可选模块？ 答：config dyn (fluid, creep, cppudm) 17、如何在圆柱体四周如何施加约束条件？ 可以用fix ... ran cylinder end1 end2 radius r1 cylinder end1 end2 radius r2 not，其中r2

FLAC3D常见命令与使用技巧

FLAC3D常见命令与使用技巧 1、FLAC3D常见命令： 是有限元程序吗答：不是！是有限差分法。 2.最先需要掌握的命令有哪些 答：需要掌握gen, ini, app, plo, solve等建模、初始条件、边界条件、后处理和求解的命令。 3.怎样看模型的样子答：plo blo gro可以看到不同的group的颜色分布 4.怎样看模型的边界情况答：plo gpfix red 5.怎样看模型的体力分布答：plo fap red 6.怎样看模型的云图答：位移：plo con dis (xdis, ydis, zdis)应力：plo con sz (sy, sx,sxy, syz, sxz) 7.怎样看模型的矢量图答：plo dis (xdis, ydis, zdis) 8.怎样看模型有多少单元、节点答：pri info 9.怎样输出模型的后处理图 答：File/Print type/Jpg file，然后选择File/Print，将保存格式选择为jpe文件 10.怎样调用一个文件答：File/call或者call命令 10.如何施加面力答：app nstress 11.如何调整视图的大小、角度答：综合使用x, y, z, m, Shift键，配合使用Ctrl+R，Ctrl+Z等快捷键 12.如何进行边界约束答：fix x ran（约束的是速度，在初始情况下约束等效于位移约束） 13.如何知道每个单元的ID答：用鼠标双击单元的表面，可以知道单元的ID和坐标 14.如何进行切片 答：plo set plane ori (点坐标) norm (法向矢量) plo con sz plane (显示z方向应力的切片) 15.如何保存计算结果答：save +文件名. 16.如何调用已保存的结果答：rest +文件名；或者File / Restore 17.如何暂停计算答：Esc 18.如何在程序中进行暂停，并可恢复计算答：在命令中加入pause命令，用continue进行继续 19.如何跳过某个计算步答：在计算中按空格键跳过本次计算，自动进入下一步 20. Fish是什么东西 答：是FLAC3D的内置语言，可以用来进行参数化模型、完成命令本身不能进行的功能

Flac3D常见问题整理

1.1常见问题及其解答Gen separate 不能被识别答：原因是FLAC3D版本不行，我用3.0的版本不能。 1. FLAC3D是有限元软件吗？答：不是，是有限差法软件。 2. FLAC3D最先需要掌握的命令有哪些？答：需要掌握gen, ini, app, plo, solve等建模、初始条件、边界条件、后处理和求解的命令。 3. 怎样看模型的样子？答：plo blo gro可以看到不同的group的颜色分布。 4. 怎样看模型的边界情况？答：plo gpfix red sk 5. 怎样看模型的体力分布？答：plo fap red sk 6. 怎样看模型的云图？答：位移：plo con dis (xdis, ydis, zdis) 应力：plo con sz (sy, sx, sxy, syz, sxz) 7. 怎样看模型的矢量图？答：plo dis (xdis, ydis, zdis) 8. 怎样看模型有多少单元、节点？答：print info 9. 怎样输出模型的后处理图？答：File/Print type/Jpg file，然后选择File/Print，将保存格式选择为jpg文件。 10. 怎样调用一个文件？答：使用菜单File/call 或者call 命令。 11. 如何施加面力？答：app nstress ran 12. 如何调整视图的大小、角度？答：综合使用x, y, z, m, Shift键，配合使用Ctrl+R，Ctrl+Z等快捷键。 13. 如何进行边界约束？答：fix x ran （约束的是速度，在初始情况下约束等效于位移约束） 14. 如何知道每个单元的ID？答：使用鼠标双击单元的表面，可以知道单元的ID和坐标。 15. 如何进行切片？答：plo set plane ori (点坐标) norm (法向矢量) plo con sz plane (显示z方向应力的切片) 16. 如何保存计算结果？答：save filename(文件名可自定义) 17. 如何调用已保存的结果？答：使用菜单File/call或者命令rest filename(文件名可自定义)。 18. 如何暂停计算？答：运行中使用Esc命令。 19. 如何在程序中进行暂停，并可恢复计算？答：在命令中加入pause命令，键入continue命令后可恢复计算。 20. 如何跳过某个计算步？答：在计算中按空格键可跳过本次计算，自动进入下一步。 21. FISH是什么？答：是FLAC3D的内置语言，可以用来进行参数化模型、完成命令本身不能进行的功能。 22. FISH是否一定要学？答：可以不用，需要的时候查Manual获得需要的变量就可以了。 23. FLAC3D允许的命令文件格式有哪些？答：只要是符合FLAC3D格式要求的文本文件，无论是什么后缀名，都可以为FLAC3D调用。 24. 如何调用一些可选模块？答：使用命令config dyn (fluid, creep, cppudm)。 25. 如何使用gauss_dev对符合高斯正态分布的材料参数进行赋值？答：假定某材料的摩擦角均值为40度，标准差是2，则命令如下：prop friction 40 gauss_dev 2 26. FISH函数中是否能调用“.sav”文件？答：不能。FLAC3D中规定，new和restore命令不允许出现在FISH函数中，因为new和restore 命令会将原有存储信息清除掉。 27. initial 与apply 有何区别？答：initial初始化命令，如初始化计算体的应力状态等；apply边界条件限制命令，如施加边界的力、位移等约束等。initial的应力状态会随计算过程的发生而发生改变，一般体力需要初始化，而apply施加的边界条件不会发生变化。 28. FLAC3D动力分析中是如何计算永久变形的？答：FLAC3D采用动态运动方程求解动力方程，因此采用弹塑性本构模型可以计算永久变形。而土动力学常用的粘弹性模型由于没有考虑土体的塑性，因此不能计算永久变形。 29. 对于初学者而言，是学习FLAC还是FLAC3D？答：FLAC有较好的图形化操作界面，而FLAC3D目前只能通过命令流来操作，从学习难度上来说，FLAC要简单一些，不过复杂的三维问题还是需要使用FLAC3D才能解决。FLAC和FLAC3D的某些命令和分析方法类似，读者在学习过程中可以相互借鉴。 30. interface建模命令中的dist关键词是否表示接触面的厚度？答：FLAC3D 中的interface 是没有厚度的，dist 关键词表示的是接触面建模时选择范围时的容差，表示该范围内的“面”上将被赋予interface 单元。 31. 初始应力场计算中位移场和速度场是否都要清零？答：是的。一般，FLAC和FLAC3D中位移场和速度场的清零命令都是同时使用的。 32. 加了fix边界，再使用apply施加应力边界有效吗？答：无效。fix和apply都是边界条件，两者不能混用，fix的作用是固定节点的速度，只要用户不更改这个速度，在计算中都会保持不变。 33. solve age后面跟随的时间是真实的时间吗？答：FLAC和FLAC3D在动力、渗流、流变模式下才有真实的时间，时间的单位默认为秒，也可以根据读者使用的量纲进行调整。

FLAC3D 实例命令流1

第1部分命令流按照顺序进行2-1定义一个FISH函数 new def abc abc = 25 * 3 + 5 End print abc 2-2使用一个变量 new def abc hh = 25 abc = hh * 3 + 5 End Print hh Print abc 2-3对变量和函数的理解 new def abc hh = 25 abc = hh * 3 + 5 End set abc=0 hh=0 print hh print abc print hh new def abc abc = hh * 3 + 5 end set hh=25 print abc set abc=0 hh=0 print hh print abc print hh 2-4获取变量的历史记录 new gen zone brick size 1 2 1 model mohr prop shear=1e8 bulk=2e8 cohes=1e5 tens=1e10

fix x y z range y -0.1 0.1 apply yvel -1e-5 range y 1.9 2.1 plot set rotation 0 0 45 plot block group def get_ad ad1 = gp_near(0,2,0) ad2 = gp_near(1,2,0) ad3 = gp_near(0,2,1) ad4 = gp_near(1,2,1) end get_ad def load load=gp_yfunbal(ad1)+gp_yfunbal(ad2)+gp_yfunbal(ad3)+gp_yfunbal(ad4) end hist load hist gp ydis 0,2,0 step 1000 plot his 1 vs -2 2-5用FISH函数计算体积模量和剪砌模量 new def derive s_mod = y_mod / (2.0 * (1.0 + p_ratio)) b_mod = y_mod / (3.0 * (1.0 - 2.0 * p_ratio)) end set y_mod = 5e8 p_ratio = 0.25 derive print b_mod print s_mod 2-6 在FLAC输入中使用符号变量 New def derive s_mod = y_mod / (2.0 * (1.0 + p_ratio)) b_mod = y_mod / (3.0 * (1.0 - 2.0 * p_ratio)) end set y_mod = 5e8 p_ratio = 0.25 derive gen zone brick size 2,2,2 model elastic prop bulk=b_mod shear=s_mod print zone prop bulk print zone prop shear

flac3d建模方法

利用FLAC3D 进行数值分析的第一步便是如何将物理系统转化为由实体单元和结构单元所组合的网格模型（Modeling ），该模型与分析对象的几何外形特征相一致。目前，FLAC3D 网格模型的建立方法可分为两种，即直接法及间接法，直接法是按照分析对象的几何形状利用FLAC3D 内置的网格生成器建模，网格和几何模型同时生成，该方法较适用于简单几何外形的物理系统；与之不同，间接法则适用于复杂的、单元数目较多的物理系统，该方法建立网格模型时，像一般计算机绘图软件一样，通过点、线、面、体，先建立对象的几何外形，再进行实体模型的分网（Meshing ），以完成网格模型的建立，FLAC3D 自身不具备间接法建模功能，读者可借助第三方软件与FLAC3D 的接入轻松实现。本章主要介绍FLAC3D 的网格建模方法，包括利用网格生成器建立简单网格、利用第三方软件进行模型导入以及复杂模型的方法。 本章要点： z FLAC3D 网格单元的基本类型 z 网格的连接 z FLAC3D 网格的数据格式 z 常用有限元模型与FLAC3D 的接入 z 复杂模型的建立 5.1 简单网格的建立 5.1.1 基本网格的形状 FLAC3D 内置网格生成器中的基本形状网格有13种，通过匹配、连接这些基本形状网格单元，能够生成一些较为复杂的三维结构网格。网格单元的基本类型和特征如表5-1所示，基本可以归为四大类，即六面块体网格、退化网格、放射网格和交叉网格。 5 FLAC3D 建模方法

表5-1 FLAC3D 基本形状网格的基本特征

5.1.2 单元网格的生成 生成块体网格（Brick ）的命令格式如下： generate zone brick p0 x0 y0 z0 p1 x1 y1 z1 …… p7 x7 y7 z7 size n1 n2 n3 ratio r1 r2 r3 或者 generate zone brick p0 x0 y0 z0 p1 add x1 y1 z1 …… p7 add x7 y7 z7 size n1 n2 n3 ratio r1 r2 r3 在该命令中，generate 为“生成网格”之意，可以缩写为gen ，zone 表示该命令文件生成的是实体单元，brick 关键词表明建立的网格采用的是brick 基本形状，p0，p1……p7是块体单元的8个控制点，其后跟这些点的三维坐标值（xn, yn, zn ），含义是由8个点可确定一个六面体网格。不过，p0～p7各点的定义需遵从“右手法则”，不能随意颠倒顺序。如果采用全局坐标系，三维坐标值应为建模空间内的全局三维坐标值；若采用局部坐标系，则除p0点采用全局三维坐标值外，其他点的坐标值都必须取其相对于点p0的三维坐标值，且在点编号后加关键词add （见本节第2行命令）。size 为定义坐标轴（x ，y ，z ）方向网格单元数目的关键词，其后跟划分的单元数目（n1，n2，n3）；ratio 为定义相邻单元尺寸大小比率的关键词，其后跟坐标轴方向相邻网格单元的比率（r1，r2，r3）。 如果生成的是长方体网格，前述命令可以简化为： generate zone brick p0 x0 y0 z0 p1 x1 y1 z1 p2 x2 y2 z2 p3 x3 y3 z3 size n1 n2 n3 ratio r1 r2 r3 或者 generate zone brick p0 x0 y0 z0 p1 add x1 y1 z1 p2 add x2 y2 z2 p3 add x3 y3 z3 & size n1 n2 n3 ratio r1 r2 r3 即只需采用4个控制点即可确定该长方体。 此外，当网格的几何形状为立方体时，上述命令文件可以用下列命令替代，进一步简化，关键词edge 后跟的evalue 是立方体的边长。 generate zone brick p0 x0 y0 z0 edge evalue size n1 n2 n3 ratio r1 r2 r3

flac3D中文使用手册

快 速 入 门(GETTING STARTED) 版本：flac3d 3.0版（FTD127） 翻译：一米 2009.06

声 明 现在市面上关于FLAC3D软件的教材寥寥无几，在学习的过程中，主要还是参考软件本身的使用手册，虽然读英文版手册有些吃力，但是它论述非常详细，我觉得是用户最好的教材。我在边看手册的时候边做了翻译，目前为止翻译完成了本部分的内容（略去了部分内容和例子），还翻译了命令手册的前半部分内容，等翻译完成了，也会和网友共享，但是像本人这类英语水平一般的人做这样的翻译工作是比较辛苦的，我也不确定是否有毅力完成命令手册下半部分的内容。虽然这样的工作比较艰难，但我觉得还是学到了不少东西，手册是最原始，最翔实的基础教材，看明白了手册，运用软件才会游刃有余。 由于本人专业水平和英语能力的限制，存在问题是在所难免的，有的地方甚至可能曲解了原意。考虑到时间因素，译文的措辞没有细细斟酌，还请网友谅解。如果发现译文中的错误，还请广大读者斧正。 一米

2 快速入门 这一部分将向初次使用flac3d的用户介绍软件的基本使用方法。主要有以下内容：软件的安装与启动；用软件分析解决问题的步骤，在每一步的操作中，都有简单例题来说明该步骤具体是如何操作的。 如果你对软件比较熟悉，但是现在很少用它来处理问题，那么这部分的内容（尤其2.7节）能很好的帮你回顾软件操作的要点。本部分3.3节全面详细的介绍了如何进行问题的求解。 Flac3d支持命令驱动和图形菜单驱动两种模式*。在本手册中大部分的算例都采用了命令驱动模式。我们认为这种模式能给用户提供操作软件最清晰的思路。在1.1节中我们就已经提到了命令驱动模式使得flac3d在分析求解工程问题时成为了一个功能强大的“多面手”。然而这种模式让新用户，或者长时间未接触软件的老用户用起来有点不那么容易。命令行必须用键盘输入，可以直接输入到软件的命令窗口，或者先保存为数据文件，再通过软件的相关命令进行读取。Flac3d能识别超过40个主命令和400多个附属的关键词。 本部分主要包括以下内容： 1 在2.1节，手把手的教你们如何在自己的电脑上安装和启动flac3d软件。 2 在2.2节，用一些简单的教学案例帮组用户熟悉一些常用的命令。 3 在用户建立自己的模型并进行分析计算之前，有必要先了解flac3d的一 些基本知识。在2.3节讲述了flac3d的基本术语；在2.4节主要说明了有 限差分网格的定义规则；而在2.5节阐述了输入命令的基本句法。 4 在2.6节，阐述了flac3d的特点，比如创建、命名和使用对象，以方便 用户进行问题的求解 5在2.7节，一步步的指导用户如何建模和分析问题，每一个步骤都分开论述，并提供简单的例子帮助用户理解。 6 2.8节－2.10节分别论述了系统的符号约定、单位体系和精度限制 7 2.11节说明了软件中各种类型文件的创建和使用。 8 2.12节对图形菜单操作模式进行了简介。 *：对于初级用户来说一般图形菜单驱动模式只进行图形输出或者文件操作。本章节的最后一部分将向用户展示如何使用图形菜单驱动模式来操作软件。

FLAC3D命令流(整理版)

1、怎样查看模型？ 答：plot grid 可以查看网格，plot grid num 可以查看节点号。 2、请问在圆柱体四周如何施加约束条件？ 答：可以用fix ... ran cylinder end1 end2 radius r1 cylinder end1 end2 radius r2 not，其中r2