svflux examples manual

8/10/2019 SVFlux Examples Manual

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2D / 3D Seepage Modeling Software

Examples Manual

Written by:Murray Fredlund, P.Eng., Ph.D.

Rob Thode, P.Eng., B.Sc.Jim Zhang, Ph.D.Todd Myhre, B.Sc.

Edited by:Rob Thode, P.Eng., B.Sc.

Murray Fredlund, P.Eng., Ph.D.

SoilVision Systems Ltd.

Saskatoon, Saskatchewan, Canada


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Software LicenseThe software described in this manual is furnished under a license agreement. The software maybe used or copied only in accordance with the terms of the agreement.

Software SupportSupport for the software is furnished under the terms of a support agreement.

CopyrightInformation contained within this Examples Manual is copyrighted and all rights are reserved bySoilVision Systems Ltd. The SVFLUX software is a proprietary product and trade secret of SoilVisionSystems. The Examples Manual may be reproduced or copied in whole or in part by the softwarelicensee for use with running the software. The Examples Manual may not be reproduced or copiedin any form or by any means for the purpose of selling the copies.

Disclaimer of WarrantySoilVision Systems Ltd. reserves the right to make periodic modifications of this product without

obligation to notify any person of such revision. SoilVision does not guarantee, warrant, or makeany representation regarding the use of, or the results of, the programs in terms of correctness,accuracy, reliability, currentness, or otherwise; the user is expected to make the final evaluation inthe context of his (her) own problems.

TrademarksWindowsis a registered trademark of Microsoft Corporation.

SoilVisionis a registered trademark of SoilVision Systems Ltd.SVOFFICE is a trademark of SoilVision Systems, Ltd.

CHEMFLUX is a trademark of SoilVision Systems Ltd.

SVFLUX is a trademark of SoilVision Systems Ltd.

SVHEAT is a trademark of SoilVision Systems Ltd.SVAIRFLOW is a trademark of SoilVision Systems Ltd.

SVSOLID is a trademark of SoilVision Systems Ltd.

SVSLOPE is a registered trademark of SoilVision Systems Ltd.

ACUMESH is a trademark of SoilVision Systems Ltd.FlexPDEis a registered trademark of PDE Solutions Inc.

Copyright 2011

bySoilVision Systems Ltd.

Saskatoon, Saskatchewan, CanadaALL RIGHTS RESERVED

Printed in CanadaLast Updated: March 25, 2013


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SoilVision Systems Ltd. Spillways Page 3 of 97

1 SPILLWAYS........................................................................................................................ 9

1.1 SEEPAGEBELOWSHEETPILING......................................................................................................9

1.1.1 Purpose............................................................................................................................9

1.1.2 GeometryandBoundaryConditions................................................................................9

1.1.3 RequestedInformation...................................................................................................10

2 CANALS............................................................................................................................ 12

2.1 NARROWCANALLATERALFLOW(PIPEFILL)....................................................................................12

2.1.1 Purpose..........................................................................................................................12

2.1.2 GeometryandBoundaryConditions..............................................................................12

2.1.3 MaterialProperties........................................................................................................13

2.1.4 ResultsandDiscussions..................................................................................................13

2.2 IRRIGATIONCANALWITHPUMPING..............................................................................................13

2.2.1 Purpose..........................................................................................................................14

2.2.2

Geometry

and

Boundary

Conditions

..............................................................................

14



2.3 PUMPSLOPE............................................................................................................................15

2.3.1 Purpose..........................................................................................................................15




3 EARTHCOVERS................................................................................................................. 18

3.1

LANDFILLSOILCOVER.................................................................................................................

18

3.1.1 Purpose..........................................................................................................................18




3.2 CHANGINGROOTZONEINRESIDENTIALSLABONGROUNDSTUDY....................................................19

3.2.1 Purpose..........................................................................................................................19




3.3

GROWING

ROOTS

......................................................................................................................

21

3.3.1 Purpose..........................................................................................................................21




3.4 DAY1......................................................................................................................................23

3.4.1 Purpose..........................................................................................................................23




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3.5 ONEDAYPRECIPITATION&EVAPORATION.....................................................................................25

3.5.1 Purpose..........................................................................................................................25




3.6 THINCOVER.............................................................................................................................27

3.6.1 Purpose..........................................................................................................................27




3.7 COVER.....................................................................................................................................29

3.7.1 Purpose..........................................................................................................................29


3.7.3 Materialproperties........................................................................................................30

3.7.4

Results

and

Discussions

..................................................................................................

30

4 EARTHDAMS................................................................................................................... 33

4.1 CLASSICEARTHFILLDAM............................................................................................................33

4.1.1 Purpose..........................................................................................................................33




4.2 RAPIDRESERVOIRDRAWDOWN..................................................................................................35

4.2.1 Purpose..........................................................................................................................35

4.2.2

Geometry

and

Boundary

Conditions

..............................................................................



4.3 FLOWBENEATHEARTHDAM.......................................................................................................36

4.3.1 Purpose..........................................................................................................................37




4.4 EARTHDAMCUTOFF..................................................................................................................38

4.4.1 Purpose..........................................................................................................................38

4.4.2

Geometry

and

Boundary

Conditions

..............................................................................

38



4.5 COMPLEXEARTHDAM...............................................................................................................39

4.5.1 Purpose..........................................................................................................................40




4.6 DAMINVALLEYSIMPLE..............................................................................................................41


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4.6.1 Purpose..........................................................................................................................42




4.7 MICADAM3D.........................................................................................................................44

4.7.1 Purpose..........................................................................................................................44




4.8 MICADAM2D.........................................................................................................................45

4.8.1 Purpose..........................................................................................................................45




4.9 DAMINVALLEY07....................................................................................................................47

4.9.1

Purpose

..........................................................................................................................

47




4.10 PRESSURESINDAM................................................................................................................49

4.10.1 Purpose.......................................................................................................................49

4.10.2 GeometryandBoundaryConditions...........................................................................49

4.10.3 MaterialProperties.....................................................................................................50

4.10.4 ResultsandDiscussions...............................................................................................50

4.11 EARTHFILLDAMSTO100.......................................................................................................50

4.11.1

Purpose

.......................................................................................................................




4.12 EARTHDAMTOE....................................................................................................................52

4.12.1 Purpose.......................................................................................................................52




4.13 CUTOFF................................................................................................................................53

4.13.1

Purpose

.......................................................................................................................

53




4.14 CLAYDAMNOTCHEDSIMPLE....................................................................................................55

4.14.1 Purpose.......................................................................................................................55





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4.15 EARTHDAMWITHTAILINGSPIT...............................................................................................56

4.15.1 Purpose.......................................................................................................................56




4.16 EARTHDAMINIRREGULARVALLEY............................................................................................58

4.16.1 Purpose.......................................................................................................................58




4.17 DRAINAGEBLANKET................................................................................................................61

4.17.1 Purpose.......................................................................................................................61




4.18

THINSLOPINGCOREDAM.......................................................................................................

64

4.18.1 Purpose.......................................................................................................................64




5 3DMESHING.................................................................................................................... 67

5.1 PINCHTWOWAY......................................................................................................................67

5.1.1 Purpose..........................................................................................................................67


5.1.3

Material

Properties

........................................................................................................


5.2 PITSIMPLE...............................................................................................................................68

5.2.1 Purpose..........................................................................................................................68




5.3 PINCHINGSIMPLE......................................................................................................................70

5.3.1 Purpose..........................................................................................................................70


5.3.3

Material

Properties

........................................................................................................

71


5.4 PILESIMPLE..............................................................................................................................72

5.4.1 Purpose..........................................................................................................................72




6 COLUMNS........................................................................................................................ 75


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6.1 HEAPCOLUMN.........................................................................................................................75

6.1.1 Purpose..........................................................................................................................75




7 WELLPUMPING............................................................................................................... 77

7.1 FLUSHINGWELLS......................................................................................................................77

7.1.1 Purpose..........................................................................................................................77




7.2 PUMPEDWELLSINGLE...............................................................................................................78

7.2.1 Purpose..........................................................................................................................78


7.2.3

Material

Properties

........................................................................................................

79


7.3 PLANINJECTOR.........................................................................................................................81

7.3.1 Purpose..........................................................................................................................81




7.4 STRAIGHTRIVER........................................................................................................................83

7.4.1 Purpose..........................................................................................................................83


7.4.3

Material

Properties

........................................................................................................


7.5 WELLDEWATERINGWITHSHEETPILING........................................................................................85

7.5.1 Purpose..........................................................................................................................85




7.6 PUMPINGWELLS.......................................................................................................................88

7.6.1 Purpose..........................................................................................................................88


7.6.3

Material

Properties

........................................................................................................

89


8 WASTEROCK.................................................................................................................... 91

8.1 WRP2....................................................................................................................................91

8.1.1 Purpose..........................................................................................................................91





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9 MINETAILINGS................................................................................................................ 93

9.1 SINGLELAYERHEAPLEACHPAD...................................................................................................93

9.1.1 Purpose..........................................................................................................................93


9.1.3

Material

Properties

........................................................................................................

93


9.2 TWOLAYERHEAPLEACHPAD.....................................................................................................95

9.2.1 Purpose..........................................................................................................................95





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1 SPILLWAYS

1.1 SEEPAGE BELOW SHEET PILING

Project: SpillwaysModel: VerticalCutoff

Sheet Piling has been driven 5 meters into a sand layer that is 10 meters in thickness. The sandlayer is assumed to extend infinitely in the horizontal direction. The sheet piling is assumed to forman impervious wall with no leakage between the individual sheet piles. The intent is to model themovement of water flow through the sand and around the bottom of the sheet piling.

Software: SVFLUXDimensions: 2DMode: Steady-stateSaturation state: Saturated flow only

1.1.1 Purpose

The purpose of this example is to illustrate the calculation of i) the flow regime, ii) the quantity ofthe flow, and iii) the maximum flow gradients at the base of the sheet piling.

1.1.2 Geometry and Boundary Conditions

The following geometry will be utilized in the creation of the model.

NOTE:Only the sand layer needs to be included in the solution. Select minimum and maximumx-

coordinates for the lateral extent of the sand layer.

Water

Sand

Impervious

(100.5, 20)(100.0, 20)

5 meters

10 meters

5 meters

Geometry Details

Figure 1


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Material PropertiesMaterial Properties are only given for the sand layer because the underlying bedrock is assumed tobe impervious. The sheet piling is also assumed to be impervious and therefore does not need tobe modeled.

SandThe sand is assumed to be isotropic and fully saturated. The saturated hydraulic conductivity is 1 x10-4 m/s. The water storage modulus is not required for a steady-state analysis.

Boundary Conditions1. The boundary between the water and the sand will have a hydraulic head boundary

condition equal to 5 meters.

2. The side downstream of the sheet piling has a hydraulic head boundary condition

corresponding to water at the ground surface.

3. The flow path down and around the sheet piling can be designated as being impervious.

4. The bottom of the sand layer can be designated as an impervious boundary.

5. The selected extents of the sand layer can be designated as impervious boundaries.

Specified Flux Section

Place a flux section through the bottom of the sheet piling for the calculation of flow below thesheet piling.

NOTE:

It is not necessary to designate initial conditions since a linear, steady-state condition isbeing solved.

1.1.3 Requested Information1. Plot the optimized finite element mesh that was automatically generated by SVFLUX.

(Show graphic output).

a. Where are the smallest finite elements located?

b. What do the smaller finite elements suggest?

2. Plot contours of the dissipated hydraulic head (Use 10 contours). (Show graphic output).

a. Where are the hydraulic head contours closest together?

b. What does the closeness of the hydraulic head contours mean?

c. Is the solution for hydraulic heads influenced by the coefficient of permeability

(hydraulic conductivity) of the sand? (Explain your answer).

3. Determine the quantity of water flow passing below the sheet piling using a flux section.

a. Perform an approximate, hand calculation to confirm the reasonableness of the

computer result.

4. Reverse all boundary conditions (i.e., set the head boundaries to impervious and vice

versa), and solve for hydraulic head contours (Use 10 contours). Set a difference in

head across the geometry of 5 meters.


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a. At what angle do the hydraulic head contours cross from the above two solutions?

5. Plot the vectors showing the magnitude and direction of the flow velocities. (Show graphic

output).

6. Plot the hydraulic gradient contours (i.e., i= change in head / change in distance). (Show

graphic output).


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SoilVision Systems Ltd. Canals Page 12 of 97

2 CANALS

2.1 NARROW CANAL LATERAL FLOW (PIPEFILL)

Project: CanalsModel: PipeFill

The Pipe Fill example demonstrates the use of SVFLUX in analyzing the situation of a narrow canal.This canal contains two concrete sidewalls of very low hydraulic conductivity. There is a berm oneither side against the concrete sidewalls. The flow through the canal and the resulting flowpatterns underneath the bottom of the concrete sidewalls are of importance in the seepagemodeling.

2.1.1 Purpose

The purpose of the seepage model is to ensure that the gradients at the bottom of the concrete

sidewalls do not get high.


The model is set up with the geometry shown below and the material regions are entered. It shouldbe noted at this time that the flux head boundary conditions are placed in the numerical model.

The boundary condition is assigned at the bottom of the canal and head boundary conditions arealso applied at the left and right sides of the model. A head boundary condition is also applied atthe base of the canal representing the elevation of the water in the canal.

Figure 2 Example geometry of the PipeFill


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2.1.3 Material Properties

The concrete is given a very low hydraulic conductivity of 3.28 x 10-12 m/s. This hydraulicconductivity corresponds approximately to the conductivity of the concrete in a very dense state.Saturated and unsaturated material properties are assigned to each material type.

When the model is run it is important to select plots of head, pore-water pressures, and gradients.The gradients in the X and Y direction may be plotted with the use of the Plot Manager. It isrecommended that these plots be specified both in the finite element solver as well as output to anACUMESH model so the model variables can be visualized. The Sand, Silt Loam and Clay regionsare given average hydraulic properties consistent with their soil type.

2.1.4 Results and Discussions

Once the model is solved, plotting the gradients will allow a better view at where the maximumgradient lies. In this case, thex-gradient has the highest value. A contour plot of thex-gradientvalues can be seen below.

Figure 3 Contour plots for the PipeFill example model

2.2 IRRIGATION CANAL WITH PUMPING

Project: CanalsModel: Irrigation

The Irrigationmodel is presented to illustrate the use of the SVFLUX software for modeling of an

irrigation canal. The Irrigation canal in this case is lined with a clay material. It is desired to see the

resulting impact on the water table when water flows through the canal. It is also desired todetermine the pumping rates that can minimize the uplift water pressure on the clay liner in acanal water-level drawdown situation.

It is assumed in this example that water is being maintained at consistent level in the canal for theduration of the numerical modeling period. A steady-state numerical model is adequate for thistype of example.


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2.2.1 Purpose

The irrigation canal is designed in an area with a high water table. Additional wells are installed inorder to pump the area around the canal to keep the water table down and minimize the flow intothe canals. As such the pumping wells on either side of the canal are included in the numericalmodel.

The purposes of this model are as follows:

1. To determine the pumping rate required to reasonably lower the water table such that the

overall flow is away from the canal, and

2. To determine the flux from the canal to the surrounding soil.


The boundary conditions on the numerical model are applied in order to determine two primaryaspects of the system. The first purpose of the model is to determine adequate pumping rates for

the wells. The approach taken with this model is a trial-and-error approach in which pumpinggradients are placed at the bottom of each well to simulate the pumping of wells.

The initial water table levels are then placed on the left and far right sides of the numerical model.The canal water level is applied to the numerical model as a head boundary condition, which isthen placed on the upper surface of the clay layer in the numerical model.

The second purpose of the model involves determining the flow from the canal to the surroundingsoil. In order to accomplish this objective a flux boundary is named and the flux across thisboundary is reported in the Plot Managerdialog. The geometry of the model is shown in Figure 4.

Figure 4 Geometry of the Irrigation Canal with pumping model


The material properties are assigned for the Sandy Clay, the Sand, and the aquifer deep in thenumerical model. The clay liner is relatively impermeable and has a lower permeability ofapproximately 1 x 10-9 m/s.


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Once the irrigation model is analyzed the user can plot pore-water pressure and flow vectors. Thiswill allow the user to see the location of the water table around the irrigation canal.

An example of resulting pore of water pressures generated by this particular model is shown in

Figure 5. By the process of trial and error, the pumping rate required to reasonably lower the watertable such that the overall flow is away from the canal is -0.002 m3/s/m2on each side of the canal.

Figure 5 Result of example model Irrigation

Once the model has been analyzed, the solver will report the flow through all flux sections. In thiscase, the flow through Flux 1 is 4.3 x 10-5m3/s, the flow through Flux 2 is 8.2 x 10-5m3/s, and theflow through Flux 3 is 4.3 x 10-5 m3/s.

2.3 PUMP SLOPE

Project: CanalsModel: PumpSlope

This model illustrates the use of SVFLUX to calculate flow out of a canal-type structure into thesurrounding soil.

2.3.1 Purpose

The purpose of this model is to calculate flow volumes which exit a canal-type structure. In thismodel the overall flow regime is established as well as calculating the specific flow volume out of

the canal.


The geometry of the model is shown in Figure 6. A clay layer of approximately 0.25m thickness isplaced over the surrounding Silty Loam material. An overall canal depth of 2.0m is represented. Aflux section is placed on the upper boundary of the clay linear in order to sum flow past theboundary.

Constant head boundary conditions are specified at 0.3 m on the right hand side of the model and1.6 m on the left hand of the numerical model.


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Figure 6 Geometry of the Pump Slope example model


The canal itself is lined with a Clay type of material of which the intent is to inhibit flow into thesurrounding Silt material. The Clay is packed along the side slopes of the canal and has apermeability of 1 x 10-6m/s. Its unsaturated properties are represented with the Fredlund and Xingfitting method for the soil-water characteristic curve and the Modified Campbell method for theunsaturated portion of the hydraulic conductivity curve.

The Silty material has a hydraulic conductivity of 1.07 x 10-4m/s and its unsaturated properties arerepresented by the Fredlund and Xing soil-water characteristic curve fitting method and theModified Campbell estimation method for the unsaturated hydraulic conductivity portion of thecurve.

A flux section is placed along the bottom of the clay linear, which flows into the resulting the rest ofthe numerical model can be calculated.


After the numerical model is run the amount of flow flux past section can be seen in the FlexPDEsolver. The hydraulic drop in head across the clay linear can be seen by plotting the head variable.

It can be seen in AcuMesh that the current design successfully dissipates a significant amount ofhead in the numerical model. The resulting water table can be also plotted in the numerical modeland may be seen in the Figure 7.


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Figure 7 Plotting of the resulting head contours as well as the resulting water table


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SoilVision Systems Ltd. Earth Covers Page 18 of 97

3 EARTH COVERS

3.1 LANDFILL SOIL COVER

Project: EarthCoversModel: Soil_Cover

This particular model is designed to illustrate the modeling of the flow regime for a landfill. Arainfall will be applied to the upper boundary of the model and the effectiveness of drains will beexamined in the model.

3.1.1 Purpose

The purpose of this model is to determine the amount of rainfall that permeates past the cover andis eventually picked up by the drainage systems. This model is created to demonstrate a coveredlandfill in which a constant rainfall is applied to the top boundary. Typically, a more comprehensive

type of seepage analysis would be performed with full climatic coupling implemented. This model issimply an example to illustrate basic concepts. A steady-state model is used for analysis.


The geometry of the model consists of a landfill pit filled with waste material, which is covered witha layer of Clay and Sand. The materials are represented by average properties that represent theoverall saturated or unsaturated characteristics of the material. The Sand layer can act as apotentially a storage layer. It will also have a potential side effect of shutting off or minimizingevaporation in this scenario.

It is assumed for the sake of this numerical model that there is a very dense material below, suchas rock or granite. As such the bottom of the model is represented as a no-flux boundary. On theupper boundary of the cover a constant flux is placed which simulates a continuous rainfallprecipitation event.

The boundary conditions are assigned as follows. Water table for the surrounding area is placed on

the left and right side of the numerical model as a head boundary condition. In this case thesurrounding water table is assumed to be fairly consistent.

Figure 8 Geometry Soil Cover model


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Once the geometry has been entered into the numerical model the material properties for thevarious materials can be input. The soil-water characteristic curve (SWCC) of the waste material,clay liner, and base material are represented by typical values in the numerical model. It would bepossible to in this case, to extract reasonable values for materials in this model from the SoilVision

database.


Once the model has been analyzed, we can find out how much rainfall travels through the soilcover by summing the reported flux values for Drain 1 and Drain 2. In Drain 1, it has a normal flowrate of -2.5 x 10-7m3/s and Drain 2 has a normal flow rate of 1.9 x 10-7m3/s. Together, the totalamount of rainfall passing through the soil cover is 4.4 x 10-7m3/s. A contour plot of the modelspore-water pressures can be seen below:

Figure 9 Results of the Soil Cover model

3.2 CHANGING ROOT ZONE IN RESIDENTIAL SLAB-ON-GROUND STUDY

Project: EarthCoversModel: ChangingRootZone

The evaporative conditions between two residential buildings are examined as vegetation growsover a period of 100 days. Development of the root zone, which acts as a sink, is considered asboth the depth of the roots and the top of the active root zone is established. This is a conceptualmodel that is part of a larger study looking at the climate effects on the shrinkage and swelling ofsoils under and around slab-on-ground foundations.

This model has a constant potential evaporation rate, constant temperature, and constant relativehumidity to isolate the effects of the transpiration variables including the leaf-area index (LAI), theplant limiting factor (PLF), and the potential root uptake due to a root depth profile and root topprofile that change over time.

The speed at which a root zone develops and the characteristics of the root profile and how theyaffect the suction profiles around the slab-on-grade foundations may affect decisions regarding thetype of vegetative cover and watering rates recommended for the site.

3.2.1 Purpose

The specific purpose of this model is to conceptually show the development of a root depth profileand a root top profile. The area in between these profiles simulates the zone from which thevegetation will extract water through transpiration.


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The specific output requested is:

1. The cumulative evaporative flow across the ground surface after 100 days,

2. The change in suction at a point near the edge of the slab, and

3. The ratio of bare soil evaporation to transpiration at 100 days.


The model geometry consists of a rectangular region 12m wide and 3m deep. The geometry of the

model is shown in Figure 10. An initial conditions head file is specified such that a linear headprofile is set starting near 0 at the ground surface and decreasing to 43.787m at the base,creating unsaturated conditions throughout the model. A head of 43.787 is maintained at thebase of the model through a constant head boundary condition. The right and left portions of theground surface are set as no flow boundaries to simulate the slab foundations. The sides of themodel are also set as no flow.

A climate boundary condition is apply to the ground surface between the 2 slabs. This climate

boundary condition calculates actual evaporation by the Wilson Limiting Equation (1997) andconsists of a constant potential evaporation specified as 0.001 m/day, a temperature of 24oC, anda relative humidity of the air equal to 50%. For transpiration, an excellent LAI and default PLFare used. A triangular root distribution is specified with the root depth increasing from 0m at day 5to 1m at day 100. Similarly, the root top increases in depth from 0m at day 20 to 0.2m at day 100.

Figure 10 Geometry of the Changing Root Zone Model


A single unsaturated material is applied to the entire model. A Fredlund & Xing SWCC fit is used todescribe the volumetric water content (vwc) changes with a saturated vwc of 0.45, af of 300kPa, nfof 1.5, mf of 3000kPa, and residual suction of 3000kPa. A leong and Rahardjo Estimation describesthe permeability, with a saturated permeability of 8.64 x 10-4 m/day and p of 1.


As the model progresses observation of the Active Root Zone contour plot shows the emergence ofthe roots at day 5 and subsequently the separation of the contours from the ground surface as the


21/97


top of the root zone takes affect at day 20. The final root zone at day 100 in terms of waterextracted in m3/day is shown in Figure 11.

Figure 11 Active Root Zone Sink Profile at Day 100

The Cumulative Climate Summary graph indicates the net evaporation across the ground surface is0.545m3, the bare surface actual evaporation is 0.206m3, and the cumulative transpiration is 0.173m3. This results in a Actual Evaporation/Transpiration ratio of 1.2. The Climate Summary graphdemonstrate the separation of actual evaporation from potential evaporation, the point at whichactual evaporation equals transpiration in day 31, and the point where the actual evaporationbecomes 0 and transpiration takes over completely at day 68.

The plot of pore water pressure at (4.2,-0.2) shows a decrease from 45kPa at the start of themodel to 464kPa after 100 days.

3.3 GROWING ROOTS

Project: EarthCoversModel: Growing_Roots

The Growing Roots example is designed to illustrate the effect of a root zone, which grows withtime. This allows the model to simulate the effect of root grown over a period o time.

Within the numerical model the growth of roots can be represented as an equation or as data.Therefore, seasonally the numerical model may estimate changes in root growth.

3.3.1 Purpose

The purpose of this numerical model is to illustrate the effect of a changing root depth with time.


The geometry of this model is shown in following Figure 12. The overall model is 3m tall and theupper boundary condition is a climate boundary condition and the lower boundary conditionconsists of a unit gradient.

The effect of the bottom boundary condition is somewhat muted because of the short time span ofthis numerical model. This numerical model is only run for thirty days and therefore the affect ofthe bottom boundary condition on the numerical model is minimal.


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Figure 12 Geometry of the Growing Roots model


The Silt is used in this model just a representation of a typical soil property. It has a saturatedhydraulic conductivity of 8.9 x 10-1 m/day. Its unsaturated properties are represented by theFredlund and Xing soil-water characteristic curve and the Modified Campbell method ofrepresenting the unsaturated hydraulic conductivity curve.

In this example the potential root uptake is entered as a function represented by data versus time.The entries specific entry of the plant root uptake may be seen in the Figure 13.

Figure 13 Entry of root growth versus time


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The results of the uptake function may be seen in the water uptake that is reported in the AcuMeshsoftware. It can be seen that the root depth increases over time. This increase is due to the growthin the root depth and therefore the water uptake function.

Figure 14 Cumulative results of the GrowingRoots model

3.4 DAY1

Project: EarthCoversModel: Day1

The Day1series of numerical models are designed to illustrate various features which have beenimplemented in the one-dimensional cover modeling set of models. For example transpiration isrepresented in one model, runoff in ponding is represented in another one.

Precipitation may be represented as either parabolic or trapezoid representation. The Penman-Wilson method of calculating evaporation is represented in one of the models in this group.

3.4.1 Purpose

The purpose of series of models is primarily is to represent the features of the climate couplingavailable in SVFLUX.


The geometry of the model is shown in Figure 15. The column consists of a six-meter column ofsoil with a climate boundary condition on the top and a no-flux boundary condition at the bottom.

Since the model is only run for one day there is enough storage to handle any particular type ofrainfall experienced during day. Therefore, a bottom boundary condition does not affect the resultsin this case.


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Figure 15 Example geometry of the Day1 series of models


In this case a grey silt material is used with a saturated hydraulic conductivity of 9 x 10 -2m/day.The Fredlund and Xing method is used to represent the soil-water characteristic curve and theModified Campbell is used to represent the unsaturated portion of the curve. This is considered anaverage soil property which may be experienced in the field.


Results of each numerical model may be examined both in the FLEXPDE solver and in the AcuMeshsoftware.

Typical results for this type of model are presented in terms of cumulative flows at the top and thebottom of the soil columns. Such flows can be plotted under the Plot > Climate Data Summarymenu option as shown in Figure 16.


25/97


Figure 16 Graph results of the Day1_Runoff model

3.5 ONE DAY PRECIPITATION EVAPORATIONProject: EarthCoversModel: OneDayPrecipEvap

This model is intended to give a very simple example of creating a one-dimensional flow model.The interest only is on determining and reporting the appropriate flows at the top boundary of themodel.

3.5.1 Purpose

The purpose of this model is to illustrate one-dimensional climate coupling for a numerical model.


The current numerical model has its base at a y- coordinate of zero. The top at a y-coordinate of3.0. The bottom of the numerical model has a unit gradient boundary condition and the top has aclimate boundary condition. The geometry of the model may be seen in Figure 17.

Figure 17 Geometry of the numerical model


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In this model a single Sandy Clay material is used which has a saturated hydraulic conductivity of2.39 x 10-1m/day and is represented in the unsaturated portions by the Fredlund and Xing soil-water characteristics curve fitting method and the Modified Campbell method of estimatingunsaturated hydraulic conductivity.


The cumulative results of the OneDay model can be seen in the following figures. It can be seenthat a parabolic application of the precipitation boundary condition is well represented. The modelultimately performs well and solves the problem as posed.

Figure 18 Cumulative results of the 1-day flows

Figure 19 Instantaneous flow volumes


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3.6 THIN COVER

Project: EarthCoversModel: ThinCover

This model illustrates the ability of SVFLUX to handle very rigorous meshing restraints whenmodeling a series of very thin covers. In this model a series of thin cover materials are placed ontop of a landfill type of material.The model is designed to provide an example of the flow regime for this type of problem. In thismodel runoff is not considered so 100% of the flow goes into the numerical model. This may beverified through the use of the flux section at the base of the cover.

Ultimately this model may be run in transient state, but given the density of the nodes a fairamount of time might be required in under to achieve a solution. Therefore, the intent of thismodel is to prove the concept of modeling thin covers over a landfill-type material.

3.6.1 Purpose

The purpose of this numerical model is to illustrate the ability to model very fine features such asthin soil layers in an earth cover setting.


The Silt material forms the base of this model. The landfill material is represented as high porosityTill. The cover is made up of three separate layers of Coarse Sand, Sand and a Clay material. Thelayering is illustrated in the following Figure 20.

Figure 20 Geometry of the ThinCover numerical model


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Figure 21 Illustration of a zoomed view of the model layering


This soil cover is made up of layers of Coarse Sand, Sandy and Clay material. Silt forms the base ofthe model. The high degree of porosity of waste materials is represented by a Till.

Cover material is ultimately represented by the Coarse Sand, which has a permeability of864m/day and Fine Sand, which has a permeability of 86.4m/day and then the underlining Clay of8.64 x 10-4 m/day. Ultimately in the long term, the flow through the cover will be prohibitedprimarily by the clay layer at the base of the designed cover.


The numerical model may be solved with a high number of nodes. The established flow regime may

be seen in Figure 22. The model is run successfully and reasonable flow regime is established inthis case.

Figure 22 Results of the ThinCover numerical model


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3.7 COVER

Project: EarthCoversModel: Cover12in1D, Cover18in1D, Cover24in1D, Cover24in1D_DailyIntensity

It is often important to model the flow amount that happens through a designed earth cover. Thefollowing three models examine at the effects of different sizes of covers on the computed rechargeor percolation values.

In this case it should be noted that we define recharge (or percolation) as flow which passes thecover system and does not get pulled back up by the process of evaporation.

3.7.1 Purpose

The purpose of these models is to evaluate the performance of different thickness of covers. Inparticular the amount of permanent long-term vertical flow, which makes it past the cover isevaluated in light of performance of the cover. The model Cover24in1D_DailyIntensity is the same

as Cover24in1D except that the Daily precipitation intensity correction is used instead of the Globalprecipitation intensity correction to demonstrate the use of this option.


The geometry for the three different cover models is shown in the following figures. The figuresconsist of a 12, 18, and a 24 cover overlying the same fine heap material.

Figure 23 Cover 12 Figure 24 Cover 18 Figure 25 Cover 24

The top boundary conditions on all the models are represented by the same climate data. Climatedata exists for all models for a minimum of time of five days. In this case the model is only run tofive days for the purposes of illustration, so that the user can get an idea of how the modelfunctions without having to wait a significant amount of time for model results.


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It is recognized that most cover model should be run a minimum time period of approximately oneyear, and possibly five, ten, fifty or even a hundred years. The bottom boundary condition on theattached models is fixed at an unsaturated head expression.

In other words this boundary condition can be interpreted as forcing the bottom of these models toremain unsaturated. This type of boundary condition set-up is typically performed if the modeling isdone conjunction with field measurements.

It should be noted that there is significant debate in research literature as far as the properrepresentative of bottom boundary condition. The user is encouraged to exam the use of unitgradient boundary conditions, as well as other variations of head boundary conditions forsuccessful cover modeling. A full discussion of appropriate boundary conditions is consideredoutside of the scope of this manual.

3.7.3 Material properties

The heap materials for all models are represented by hydraulic properties representatives for heapmaterial. The fines for the cover materials are all of consistent porosity and hydraulic conductivity.


The results of the one-dimensional models are presented in terms of total cumulative fluxes whichproceed past the top boundary condition. It is also desired in this case to determine the total flowwhich passes beneath the cover in each of these scenarios. In another words, what is the impact ofincreasing the cover thickness on the amount of percolation past the base of the covers.

The amount of flow that goes past the cover system can be obtained by placing a flux section atthe base of the cover. The results of the current models are shown in Figure 26. The figure may beseen under the Plot > Climate Summarymenu option.

It should be noted that the user may also report pore-water pressures and saturation levels atvarious points throughout the numerical model. This is illustrated in the following graphs.

It should be noted that runoff is not accounted for in the attached models. This is because therainfall events are not high enough intensities to get close to runoff conditions.

It should be further noted to display the results of the pore-water pressures at certain points, thedata must be selected to write to a text file in the Plot Propertiesdialog.

It can be seen that there is little variance in the short time frame between the various coverscenarios. More significant variance is expected in the longer term under which this model wouldtypically be run.


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Figure 26 Flux 2 from the 24-inch cover model

Figure 27 Example of the cumulative results from the software

Figure 28 Cumulative flow past the 18-inch cover


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Figure 29 Cumulative flow past the 12-inch cover


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SoilVision Systems Ltd. Earth Dams Page 33 of 97

4 EARTH DAMS

4.1 CLASSIC EARTH FILL DAM

Project: EarthDamsModel: Earth_Fill_Dam, T_Earth_Fill_Dam

The earth fill dam example is the classic numerical model which is often solved in numericalmodeling classes in Universities. The model is used to assess the effectiveness of a clay core indissipating the energy of water. The effectiveness of a downstream filter is also examined in orderto avoid possible piping failures. If the downstream filter operates properly there will be no outflowof water on the downstream face of the dam.

Model Earth_Fill_Dam examines the steady-state scenario and is described in this example.T_Earth_Fill_Dam verifies a transient model, where the upstream boundary condition remainsconstant against the steady-sate model.

4.1.1 Purpose

The purpose of this example is to examine the flow regime through an earth dam in order toachieve the following objectives:

1. It is desired that the energy in the water head must be reduced through the use of theclay core in the dam.

2. It is desired that the water table must not daylight on the down-stream side of the earthdam.

In order to keep the water table from day lighting on the down stream on the earth dam a filter isplaced at the base of the dam, which provides a drain for the water. This model is also a classicillustration of the potential for unsaturated flow over the clay core.


The geometry of this model is created using three separate regions in the numerical model. Thesethree regions are named the damregion, the coreregion, and the filterregion. It should be notedthere are several ways to input the core region. Firstly, it could be an exclusion of the dam region.Secondly, it could also be drawn such that the dam region goes up and around the clay core. Inthis example we will exclude the core material from the earth dam material.

Boundary conditions may be applied to the numerical model. A head boundary condition can beapplied on the upstream side of the earth dam. In this case we assume the upstream waterboundary conditions are constant with time.

As such, this allows the current numerical model to be analyzed as a steady-state numerical model.A head boundary condition is placed at the base of the filter material on the downstream side ofthe earth dam. This allows free drainage of the water through the earth dam. A flux section is alsoplaced such that the volume of flow through the earth dam can be calculated.


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Figure 30 Geometry of the Earth Fill Dam model


The material properties in this numerical model are entered such that the material in the dam

region is made up a Till type of material with a uniform grain-size distribution. The core materialis made up of dense clay with a very low hydraulic conductivity. The filter material consists of asandy gravel type of material with a high conductivity.


Once the model is analyzed the interest is in the amount of flux over the top of the clay core, thetotal flow through the earth dam, and the location of the phreatic surface. The flow up over theearth core may be visualized by plotting flow vectors in the dam region. The flow vectors show the

water flow up over the earth core and through the unsaturated zone (Figure 31).

Figure 31 Vectors showing the concentration of high fluxes

Once the model has been analyzed, the solver will report the flow through all flux sections. In thiscase, the flow through Flux 1 is 2.0 x 10-8 m3/s, the flow through Flux 2 is 7.7 x 10-9 m3/s, and theflow through Flux 3 is 1.4 x 10-8 m3/s.

The location of the phreatic surface may be seen by plotting pore-water pressures. The zeropressure line can be seen to go to decrease deeply through the core and subsequently exist at thepoint of the filter. This is desirable, as the water table does not approach the downside of the earthdam.


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Figure 32 Pore-water pressure contours through the earth dam

4.2 RAPID RESERVOIR DRAW-DOWN

Project: EarthDamsModel: T_Earth_Fill_Dam_RDD

In this example, the rapid draw-down of a reservoir is examined. The reservoir creates abnormallyhigh pore-water pressures in an earth fill dam, and subsequently creates a slope stability failurehazard. Proper calculation of upstream pore-water pressures is therefore important.

4.2.1 Purpose

The purpose of this model is to determine the pore-water distributions in the earth dam duringrapid draw-down conditions.


The geometry used in this numerical model is the same as the geometry used for the other earth

filled dam example model. The initial head specified is the same as the other steady-state exampleas well.

The preliminary difference in this new numerical model is the head boundary condition is drawn-down very rapidly over the duration of the numerical model. The pore-water pressures can beexamined along the upstream side of the earth dam at any point in time.

Figure 33 Example geometry of the T_Earth_Fill_DamRDD model


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The same material properties are used in this numerical model as were used in the previous EarthDam numerical model.

4.2.4 Results and DiscussionsOnce the model is run, pore-water pressures can be seen on the up-stream side of the earth dam.Subsequently, this model can be put into a slope stability analysis and the resulting factors ofsafety at any given step can be calculated. The results of the pore-water pressures can be seenbelow:

Figure 34 Initial Pore-Water Pressures in T_Earth_Fill_DamRDD

Figure 35 Final Pore-Water Pressures in T_Earth_Fill_DamRDD

4.3 FLOW BENEATH EARTH DAM

Project: EarthDamsModel: EarthDamLow

This particular numerical model must illustrate the use of seepage software to determine therelative flux which might occur through as compared to underneath an earth dam.


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4.3.1 Purpose

The end user may want to determine the amount of flow which may pass through an earth dam asopposed to underneath an earth dam. It is costly to excavate too deeply into highly impermeablematerial beneath an earth dam.

The earth dam may therefore then built on materials that are of low permeability. Materialsbeneath earth dams are rarely completely impermeable and therefore flow beneath such astructure is of importance.


The geometry of this numerical model may be set up such that there is an upstream anddownstream type of material. The clay core is placed in the center of the dam as a highly denseand relatively impermeable layer and two subsequent layers are placed underneath the earth damto represent the material of the original landscape.

The boundary conditions assigned to the numerical model are placed on the upstream anddownstream sides of the earth dam as well as the far left and right side of the numerical model.

And it is assumed that a head boundary condition adequately represents the upstream condition forthis numerical model. It is also assumed the head boundary condition does not change with time

and therefore the scenario may be modeled with a steady-state analysis.

A head boundary condition is placed on the upstream part of the earth dam. The downstreamboundary condition is placed on the far right hand side of the numerical model, which representswater table readings obtained in the field. A flux section is placed in the model in order to integratethe total amount of flow through the model.

Figure 36 Example geometry of Earth Dam Low


The material properties entered into the current numerical model are such that the earth-fillmaterial is of average permeability.

The clay core has a very low permeability and illustrates the dense or the packed-clay core of theearth dam. The hydraulic properties of the two material layers on the original ground surface wouldbe determined based on laboratory measured material properties. Since the two material layersbeneath the earth dam will remain predominately saturated during the analysis, it is not critical tohave unsaturated material properties for these two soils.


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It is reasonable, however, to obtain unsaturated material properties for the earth dam and claycore materials as the levels of saturation in both of these materials are unknown prior to runningthe model.


Once the model has been analyzed, the solver will report the flow through all flux sections. In thiscase, the flow through Flux 1 is 1.3 x 10-3 m3/s. The distribution of pore-water pressures and thewater table may be seen in the Figure 37.

Figure 37

4.4 EARTH DAM CUTOFF

Project: EarthDamsModel: EarthDamCutoffFlow

One of the types of analysis that can be done is to examine the use of a cutoff wall created byinjecting grout underneath the earth dam. This is often performed if the material beneath the

location of an earth filled dam is considered to be very porous, or fissured and therefore thehydraulic conductivity of the sub layer must be decreased.

Such a scenario can be modeled in the software and this example is designed to illustrate how sucha scenario might be solved using SVFLUX.

4.4.1 Purpose

The purpose of this example is to illustrate the calculation of the amount of flow past a groutedcutoff wall.


The model is analyzed as a steady-state model and the head boundary conditions on the upstreamside of the earth dam are considered to remain constant.


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Figure 38 Geometry of Earth Dam Cut Off Flow model


The cutoff material is assigned hydraulic conductivity of concrete roughly 3.28 x 10-12ft/s.


Once the model has run the resulting flow regime can be analyzed. It is also simple to extend orshorten the length of the cut off and examines the resulting impact on the flow regime.

Figure 39 Results of the Flow Regime of the Earth Dam Cut Off model

Once the model has been analyzed, the solver will report the flow through all flux sections. In thiscase, the flow through Flux 1 is 2.6 x 10-4 ft3/s, and the flow through Flux 2 is 6.0 x 10-3 ft3/s. Thetotal flow through the dam is 6.2 x 10-3ft3/s.

4.5 COMPLEX EARTH DAM

Project: EarthDamsModel: ComplexDam


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This model is created in the SVFLUX software and the geometry was digitized and imported froman AutoCAD DXF file.

4.5.1 Purpose

The purpose of this numerical model is to illustrate the ability of SVFLUX to automatically to createa mesh and analyze a very detailed earth dam cross-section. A complex layering is introduced inthis particular example. It would impossible to analyze such a model with a manually generatedmesh.

This model, however, is straight-forward to solve by using the SVFLUX software. The secondpurpose of this model is to determine the total flow through the earth dam. The third purpose is todetermine the location of maximum gradients.


Once the geometry has been successfully entered the boundary conditions may be specified. In thiscase, a head boundary condition is placed on the up streamside of the earth dam. The reviewboundary condition is placed on the downstream side of the earth dam because the exit point ofthe water is not exactly known.

The user may then vary the material properties to determine the resulting change in the location ofthe downstream water table or exit point of the numerical model. It is also possible to place a fluxsection on the earth dam at several places in order to determine the overall fluxes through theearth dam.

Figure 40 Geometry of the Complex Dam model


The material properties for this earth dam are entered as a number of different materials, whichadequately represent the material layers used in the construction process.

While it is not recommended that this type of analysis to be performed without unsaturatedmaterial properties, specifying only saturated properties provides a good initial guess at thesolution. Only saturated material properties are utilized in this model.


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The first purpose of this model was to illustrate the ability of SVFLUX to automatically to create amesh and analyze a very detailed earth dam cross-section. A mesh plot of the model solution ispresented below.

Figure 41 Mesh Plot of the Complex Dam modelOne desired output from this numerical model is the location of the phreatic surface as well as thelocation of any critical gradients that which may occur in this cross-section, the overall flux to theearth dam is important as well as determining the potential day-lighting location of a potentialphreatic surface.

An indication of these types of output can be obtained by using the Plot Manager. In the PlotManager, contour plots of pore-water pressures and heads may be created to determine the energyloss through the earth dam and the location of phreatic surface. The pore-water pressure resultscan be seen in the following ACUMESH figure:

Figure 42 Pore-water pressures results of the Complex Dam model

A flux section can be placed across the earth dam and the flux value integrated across the entirethe earth dam. A plot of gradients can be also created in the Plot Manager and resulting output canbe viewed in the either finite element solver or professional quality reports can be created in theACUMESH software. The flow across the Flux 1 flux section is 9.4 x 10-5 m3/s.

4.6 DAM IN VALLEY SIMPLE

Project: EarthDamsModel: DamInValley07


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This model is attended to illustrate the application of the software to a situation in which an earthdam is placed in a valley. It is attended to be a fairly simple example with a homogenous dammaterial.

4.6.1 Purpose

Although this is a relatively simple model conceptually the numerical modeling challenges with thismodel design are significant. Typically problems include how to pinch out layers of the model onthe valley sidewalls.

Although this model contains straight-forward known points on all the dam valley walls, it is still auseful model to determine the proper methodology for designing this type of problem. We willplace a flux section across the downstream side of the dam and examine the amount of flowthrough the dam.


Figure 43 Example geometry of the Dam In Valley Simple

The model geometry is comprised of three primary layers in this case. The bottom layer is flat andis selected to be far enough away from the model such that it does not unduly influence the modelparameters. A second surface represents the ground surface of the valley without any damstructure in it. It is comprised of two upper zones and the valley sidewalls and the valley

basement. The third surface represents the top of the earth dam and it crosses the valley topologysurface at certain intersections points.

The primarily difficultly with this model is determining the points at which there is intersectionsbetween surfaces two and three. The topology and the earth dam itself. In this case theintersection points are determined, using a geometry tool called, find regions. With this tool, the

intersection points between two surfaces could be found in the numerical model and converted to aregion.

It is ideal in a three-dimensional numerical model that a region can be cut through a surfaceexactly at the intersection point between the two surfaces. The second region is selected as theentire geometry extents. Therefore, the current model is comprised of three surfaces and two


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regions. The first region is the entire numerical model, and is rectangular in shape. The secondregion represents the earth dam, and the intersection between surfaces two and three.

The earth dam can be also be limited to the first or the second layer such that the properties of theearth dam do not extent down in below the topology of the soil. This may be accomplished bydouble-clicking on the Earth Dam region and selecting the Limited Regionbutton, and excludinglayer one from the earth dam region. This will cause the numerical model to ignore the extensionof the earth dam into the layers below the original valley topology.

The boundary conditions for the earth dam are a water table, which is placed on the upperupstream side of the earth dam. The earth dam region is selected and surface boundary conditionsmay be applied to the upstream side of the earth dam. These upstream head boundary conditionscomprise an infinite source, which represents a reservoir.

Once the model is created the series of head and pore-water plots may be created under the PlotManager form the default plots provide a reasonable illustration of the heads and pore-waterpressure water contours throughout the earth dam. The gradients may be plotted at any two-dimensional slice through the earth dam. Three-dimensional plots may be visualized by selectingAcuMesh output in the output manager.


Typical values for Till and earth dam fill were used for the model.


This example however, straight forward illustrates key concepts in the creation of an earth dammodel, which are useful for more complex applications of this theory. Complex issues such aspinching out and limiting regions to certain layers are illustrated with this numerical model.

Also illustrated is the application of boundary conditions to surfaces. However, simple this modelforms the basis for the creation of much more complicated earth dam numerical models.

Once the model has been analyzed, the solver will report the flow through all flux sections. In thiscase, the flow through Flux 1 is 2.8 x 10-3 m3/day.

The below figure displays the contour plot for the analyzed model:

Figure 44 Contours of pore-water pressure for the final solved model


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4.7 MICA DAM 3D

Project: EarthDamsModel: Mica Dam 3D

The Mica Dam earth model is a model made from the real 3D world earth dam case. The model isdesigned to illustrate the use of the SVFLUX to set and up solve the geometry associated with thistype of real world problem.

4.7.1 Purpose

The purpose of the model is to illustrate the solution of a real world three-dimensional earth dammodel by the software.


The approximate three-dimensional view of the numerical model may be seen in the followingfigure. The mica earth dam in actual reality is created using a clay core and granularly outside

material. Since this is a flow model there is no need to model the gravel core, as its conductivity ismultiple orders of magnitude more conductive then the clay core.

Almost all the head loss occurs through the clay core of the earth dam. Therefore, only the clay inthe core of the dam is included in the numerical model. A certain amount upstream anddownstream is created using the numerical model such that the boundary conditions do notinfluence the model results.

The numerical model is created using a series of four surfaces. The top and the bottom surfaces ofthe valley are represented in the numerical model firstly. Then subsequent surfaces, whichrepresent the top and the bottom of the clay core, are entered into the numerical model.

The results in several surfaces cutting through the topology of the dam valley and in order to

successful create the clay core. It should be noted that there is extensive use of the setting ofminimum evaluations in order to cause the portions of the clay core, which fall beneath the valleyto not be included in the numerical model.

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