Vertical Drain Consolidation Analysis With MCC Model

8/11/2019 Vertical Drain Consolidation Analysis With MCC Model

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Vertical Drainage Consolidation Analysis with MCC Model

Soft GroundSoft Ground

Soft Ground Tutorial


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00 Vertical Drainage Consolidation Analysis with MCC ModelOverview

Banked consolidation analysis

applying drain material of both

sides drainage condi tion w ill be

performed using Modified Cam

Clay(MCC)Model.

Model the vertical drainage using

Embankment

draining boundary condition

Simulate the Initial, Embankment

and Leave stages.

Clay 1

Clay 2

The ground settlements and

excess pore pressure due to

embankment will be checked.

Clay 3

Weathered Rock

Vertical Drainage

Vertical Drainage Consolidation Analysis with MCC Model 1


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01Material Property

ID 1 2~4 5Ground Material Properties

Name Embankment Clay 1~3 Weathered Rock

Constitutive Model MC MCC MC

Modulus of Elasticity

[tonf/m2]3,000 300 15,000

o sson s a o . . .

Unit Weight (Y) [tonf/m3] 1.80 1.96 2.10

Saturated Unit Weight

(Ysat) [tonf/m3]1.85 2.00 2.10

Cohesion c tonf/m2 1.5 - 3.0

Internal Friction Angle () 25 - 35


ermea y m ay .


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01Material Property

Ground Material Properties (MCC Properties)ID 2 3 4

Name Clay 1 Clay 2 Clay 3

Over Consolidation Ratio (OCR) 1 1 1

Slope of Normal Consolidation Line () 0.217 0.217 0.217

Slope of Over Consolidation Line () 0.043 0.043 0.043

Critical State Specific Volume () 3.579 3.817 4.928

Slope of Critical State Line (M) 0.772 0.772 0.772

Although MCC Model properties determined by triaxial compression test, which also can be estimated through

using general properties calculated by the formulations shown below in roundabout way.

303.2

c303.2

s

z e1

ln pc N ln

sin3

s n


2 0p

3


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02Import > CAD file(*.dwg/*.dxf)Procedure

Select the SoilWorks excution

icon from the Desktop.

21

Project Manager> click Soft

Ground

Initial Parameters > click User2

1

4

Select [ton] , [m] and [day]

Main Icon > Import > select CAD

3

3

4

.

Select the Vertical Drainage

Consolidation Analysis with MCC

Model.dwg, and click [Open]

5

Unit of Force and Length are

converted automatically, but unit of

Time is not converted

5

. ,

the unit of Time when performing

the consolidation analysis.

User can copy and paste the


objects in CAD program directly

into SoilWorks.


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03Model > Ground Material PropertyProcedure

From Main Menu, select Model >

Ground Material Property

1

21

Refer to Step 01. to enter the

ground material properties and

click Add.

2

Click [Close]3

SoilWorks permits ground material

properties used in projects to be

compiled in a database. The

3

database is created by editing the

*.gdb file in SoilWorks/Dbase in the

Install folder.



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04Geometry > Smart SurfaceProcedure

For generating the surfaces to

assign the material properties 2

43

1

From the Main Menu, select

Geometric Shape > Auto-

generate Surfaces (command: ss)

1


Window > Display Settings ( )

>

2

3

5

Select Change Background

Color > Attribute Color

Click OK

4

5

Property not entered currently will

be set basically as gray and

changed as property color defined

when property data entered, which


for composite model.

St


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05 Assign Material PropertyProcedure

Assign the ground material property.

Refer to Page 1 to select the1

surface of Embankment, and

select Embankment under

Ground Material Property frome or s ree an rag

Drop.

1

Using the same way to assign the

property to area relevant to [clay

layer 1~clay layer 3, weathered


St


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06 Generate Mesh SetProcedure

Generate ground mesh sets.

From the Main Menu, select1

1

2

6

Model > Edge Seed (command :

es)

Click the Select All 2

3

Specify 0.5m as the Division

Interval

Check the location of generated

3

45

47

8

Click [OK]


Model > Smart Mesh command :

5

6

sm)

Check off Register each Mech Set

by Domains In case that there is no calculated element between drainage materials, mesh should be generated

for more than 3 elements to be existed at least because normal anal sis is hard to be erformed.

7

Click [OK]

Generated mesh will be registered

8

1

1 2 3 4


to Works Tree > Mesh > bottom of

mesh set with assigned name.

8

O

X

O

Step


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07 Define Boundary ConditionsProcedure

Define the ground supports.


1

4

Loads | Boundaries > Smart

Support (command : as)

Enter the name of Boundary Set

2

Click [OK]

Define the boundary condition for

the drainage

2

3

3

From the Main Menu, selectLoads | Boundaries >

Draining Condition

4


Select the Curve from Type

Select the line(vertical drain

5

6

7

material, both sides drain) relevant

to drain condition

Click [OK]88

6

7


Step


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07 Define Boundary ConditionsProcedure

Define the Non-consolidation

Boundary Condition

16


Loads | Boudnaries >Non-

Consolidation Boundary

1

2

3

4

3


Select the Mesh from the Type

2

3

5

Select the mesh relevant to

embankment material.

Click [OK]

4

5

Define the water level


Loads | Boundaries >Water

6

Level

Select line placed by the water

level.

7

7

8


Click [OK]

10

8

Step


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08 Define Construction StagesProcedure

Define the construction stages


1

Analysis | Design > Construction

Stage

Click the Add Construction Stage2

2

3

4

Enter 3

Click [OK]

Select the Construction Stage 1

3

4

5

Enter Initial

Click the [Time Steps]

Create the time and number of

6

5

7

8

8

steps (Period: 1, No. of Steps: 1)

Click [OK]

Check on Water Level, and select

9

10

10

7

6

the Water Level function

Check on Initialize Displacement

Click [Modify]

1111

12 9

12


.

11

Step


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Define the time steps for each stage

Select the Construction Stage 2, and1

1

2

3

4

enter Embankment

Click the [Time Steps]

Enter Period > 45, No. of Steps > 10

2

3

Check on Save Result

Click [Create Steps]

Click [OK]

4

5

6 6

7

Click [Modify]7

The number of step is an item

defining the force increment size

Although defining more number of

step to generate the unequribrium

force can get excellent astringency,

the analysis time will be longer at the


. ,

input 300 to period, 20 to number of

step in stage of Leave.

12

Step


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Define the mesh set, boundary and

load set for each stage

1


Analysis|Design > Stage

Models 2 4

1

Select the Initial stage

Drag&Drop the Clay Layer,

Ground Support, Drainage

2

3

stage as data for adding to current

stage.

Click [Apply]4

3

A l the mesh and boundar set

of construction stage in same way.

Checking the Simulate Each

Stage, the element added/removed


can e c ec e eas y.

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Define the mesh set, boundary and

load set for each stage

3

1

Select the Embankment stage

Drag&Drop the banking material

mesh and banking

2

1

2

condition as data added to current

stage.

Click [Apply]3

In the Leave stage, there is no

add/ remove for element

4

4

A l the mesh and boundar set

of construction stage in same way.

Checking the Simulate Each

Stage, the element added/removed


can e c ec e eas y.

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09 Define Analysis CaseProcedure

Define the analysis case.


71

Analysis | Design >Analysis

Case

Click [Add]2

3

4

2

Enter Consolidation Analysis

Select Construction Stage Analysis

from Analysis Method

3

46

Click [OK]

Click [Close]

5

6

Perform analysis

From the Main Menu, selectAnal sis Desi n > Anal sis

5

7

Click [Perform Analysis]8

8


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10 Analysis of Results (Settlements)Procedure

Check the settlement of ground

surface due to embankment

24

Select Workstree > Results >

Leave [Time:346, Load Factor :

1.000] > Displacement > Vertical

Displacement(DZ(V))

3

1


Results > Result Tag ( )

Click the node on the round

2

3

1

3

surface


Results > Extract Result

4

5

Value ( )

Select Vertical Displacement(DZ(V))

Click [Select All ]

5

6

Select the nodes of earth surface or

enter the nodes number.

Click [Table]

7

8

6

7


Check the results

16

9

8


10


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10 Analysis of Results (Settlements)Procedure

Analyze the settlement with time

Paste the previous earth surface1

nodes result table to Excel Sheet.

Using time on step as time unit

to generate graph.

2

In consolidation analysis, because

of the settlement happened by

sperse o excess y ros a c

pressure depends on time, the

Time Step should be adjusted to

perform analysis until judging the

excess hydrostatic pressure has

been completely dispersed, in

other words the settlement of

earth surface is converged to a


certain value.

17


10


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10 Analysis of Results (Excessive Pore Pressure)Procedure

Check the excess pore pressure

due to embankment

25

Select Workstree > Results > Leave

[Time:346, Load Factor : 1.000] >

Ground Element Stresses >

Excessive Pore Pressure

1

4

3


Results > Result Tag ( )

Select Element from T e

2

1

Click an element


>

3

4

5

( )

Select Excessive Pore Pressure5

Select the nodes of earth surface or

enter the nodes number.

7

8

6

7


Check the result

18

9

8


10


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10 Analysis of Results (Excessive Pore Pressure)Procedure

Check the excessive pore pressure

with time.

Paste the previous earth surface

nodes result table to Excel Sheet.

Using time on step as time unit to2

1

.

Because of the settlement

appene y sperse o excess

hydrostatic pressure depends on

time, the Time Step should be

adjusted to perform analysis until

judging the excess hydrostatic

pressure has been completely

dispersed, in other words the

settlement of earth surface is


converged to a certain value.

19

Embankment Leave


11


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11Analysis GuideConsolidation Analysis

Consolidation Analysis is an analysis method calculating the process that excess pore water pressure disperses depending on time in case that water resist to

external force. Because water which cannot escape due to undrained condition and resisting to load will escape slowly as time goes by through drain condition

boundary, excess pore pressure decreases over time, and internal force shared by water is transferred to be resisted by soil to raise soil deformation, also

increase the soil effective stress. The method of performing consolidation analysis can be divided into 1 one-dimensional consolidation according to theoretical

function and finite element method.

In case of one-dimensional consolidation, there is an advantage by which result can be easily obtained with simple procedure. But it is limited to two-

dimensional analysis and can not be used in general composite shape of ground analysis.

For finite element method, the limitation for shape mentioned previously or general analysis is not so much but a weakness is exist that time spent on modeling

and analysis is much. Soilworks supports both one-dimensional consolidation analysis and finite element consolidation analysis.

In consolidation analysis, elements will get DOF of pore water pressure additionally with displacement DOF at nodes.

Consolidation analysis in SoliWorks will assume all elements get DOF of pore water pressure if two kinds of boundaries, non-consolidation condition and drain

. , -

general structure element as shown below. In case of boundary happened drain in consolidation element, the drain condition must be defined. When the

boundary condition defined normally and consolidation analysis has been performed, the excess pore pressure applied non-consolidation condition and drain

condition should be 0.


[ Boundary Condition of Consolidation Analysis ]

Documents

Vertical Drain Consolidation Analysis With MCC Model