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The October GeoStudio TechTalk introduced you to the GeoStudio Core bundle, including common use cases that can be analysed using the products included in the bundle.

This video will take you through the step-by-step process of defining the analysis tree, materials, and geometry, followed by reviewing the results of an example project.

The GeoStudio Core bundle combines the three GeoStudio products that are most commonly used in engineering projects: SLOPE/W, SEEP/W and SIGMA/W. The integration of these three products can help you achieve realistic results for various real-world problems.



Vincent Castonguay


1 hr 4 min

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Video Transcript

<v Vincent>Hello, and welcome to this GeoStudio Tech Talk.</v>

These monthly webinars are designed to improve

understanding of the software

and ultimately promote success in engineering projects.

This month’s Tech Talk will feature GeoStudio Core

integrating SLOPE/W, SEEP/W, and SIGMA/W

to solve complex problems.

I’m Vincent Castonguay.

I work as a research and development specialist

with the GeoStudio Business Unit here at Seequent.

Today’s webinars will be approximately 60 minutes long.

Attendees can ask questions using the chat feature.

I will respond to these questions via email

as quickly as possible, and a recording of the webinar

will be available so participants can review

the demonstration at a later time.

GeoStudio is a software package

developed for a geotechnical engineers

and earth scientists comprising several products.

The range of products allows users

to solve a wide array of problems

that may be encountered in these fields.

Today’s would be in our relates specifically

to three of our products, SLOPE/W, SEEP/W, AND SIGMA/W.

Those looking to learn more about the products,

including background theory, available features,

and typical modeling scenarios

can find an extensive library of your sources

GeoStudio website.

There you can find tutorial videos,

examples with detailed explanations

and engineering books on each product.

Let me start this webinar by showing you

this beautiful picture of a slope plunging toward the sea.

This is either a tourist dream spot

or the geotechnical engineers nightmare,

depending on who’s looking at it.

A geotechnical engineer will naturally see option two.

This complex, natural geological feature

will often be turned into a 2D representation

stripped of as much of the complexities as possible

to understand the key mechanisms, controlling behavior.

A question a geotechnical engineer might need to answer

regarding this slope is, is the slope stable?

To better represent the problem

and be able to properly answer the questions

we might have to consider the water conditions

that exist in the slope.

Where’s the water table?

How does it affect shear resistance?

We might also need to consider if there are stresses

and strain conditions that affect the slope as well.

Once all of these elements are considered,

then we can begin to answer the engineering question

and proceed to a slope stability analysis.

The process I just described

is exactly what this webinar’s all about.

How can we use the GeoStudio Core products

in an integrated way to solve a complex engineering problem?

In this webinar,

we will first review the GeoStudio Core products.

Next, I will spend a moment discussing

the numerical modeling process

and the important aspects to consider,

to conduct a successful numerical analysis.

Finally, I will demonstrate how to put this on into practice

by creating an example where the construction sequence

of two embankment is simulated

using the full GeoStudio Core lineup of products.

Let’s dive into it by reviewing each product

that composes the GeoStudio Core lineup.

As I mentioned earlier,

GeoStudio Core refers to the three most popular products

part of the GeoStudio portfolio.


SLOPE/W is a limit equilibrium stability application,

where a slope is split into a number of slices,

driving in resisting forces are calculated

within each slice,

and factors of safety are computed.

Slope is all fundamentally about comparing resistance

versus driving forces.

Water seepage is often a governing factor

in many geotechnical problematics.

SEEP/W is a finite element software

where a domain is disguised into small elements

in order to resolve the water balance within the domain.

SEEP/W will help establish water conditions

that can then be used by other modules in GeoStudio.

Finally, SIGMA/W is the stress-train modeling module

in GeoStudio.

Similar to how SEEP/W functions,

SIGMA/W disguises a domain into finite elements,

but this time to resolve the force-displacement equilibrium.

SIGMA/W helps establishing the stresses and strains

that exist within a domain.

The strength of the GeoStudio Core package

lies within the tight implementation

of the various physics that interact with each other.

Groundwater conditions calculated with SEEP,

can be made to influence the stresses and strains

that are calculated with SIGMA/W.

Both of these physics can in turn,

be brought in to SLOPE/W

to calculate the stability of a slope or earth structure.

Each model can be made to impact the others in various ways

that we will discuss in this webinar.

Let us now focus on the numerical modeling process

and what are some of the important aspects to consider

when setting up a more complex numerical analysis.

Using SEEP/W and SIGMA/W in conjunction with SLOPE/W

brings some new challenges that need to be addressed,

especially for users who are more experienced

with using SLOPE/W alone.

Imagine I have an engineering problem to solve,

and I wished to proceed via numerical modeling

to help me with this task.

I will first need to conceptualize the problem at hand

so that I can subject my conceptual model to analysis.

So for example,

this slope that I showed at the beginning of the webinar

could be conceptualized as the following geometry.

Conceptualization has at its core

the idea of simplification.

When performing numerical simulations,

we tend to over complicate the geometries that we use

probably in fear of missing out on important details.

If you go back in mere 10 or 20 years,

trying to solve very complex geometries

would have been almost impossible

because of lack of computational power.

Nowadays however, the most basic laptops

can solve quite complex problem.

So in a way, there’s a tendency to avoid simplifying

problem geometries

because we know the computer can handle it.

But the point remains that simpler geometries

often lead to easier results interpretation.

We should thus simplify as much as we can

and come back later on when we have a good grasp

on what the results mean

and add more complexity, if necessary.

The next step to solve the numerical modeling problem

would be to carefully choose the physics

that apply to the problem at hand.

I like to view these physics

in terms of GeoStudio products.

For example, if I’m trying to model

the effect of disappearing permafrost under a culvert,

I’ll need to include in my model SEEP/W

to account for water transfers,

TEMP/W to simulate the heat exchanges,

and SIGMA/W to compute the resulting stress-strain behavior.

Any engineering problem should be carefully studied

to decide what physics apply into consequently,

which GeoStudio module should be included in the analysis.

As we add physics into our models,

we also need to choose which constitutive laws

will correctly represent to soil behavior.

A constitutive law is a set of mathematical equations

that wishes to translate real soil behavior

into computer language

so that GeoStudio can adequately model the soils

in a way that fits the field reality.

Constitutive laws exists to represent

the stress-train behavior of soils, for example,

or the ability to transfer water and heat

or any other behavior feature we deem important

in our simulations.

Various parts of a domain can require

distinct constitutive laws

as the materials might behave quite differently.

Choosing the appropriate constitutive law

for a particular soil requires knowledge and experience.

While it is not necessary to know and understand

every intricate detail of the workings

of the various constitutive laws,

it is important to have a general understanding

of the models we choose to use.

Otherwise we might be unable

to correctly interpret the results.

The next item on the list to define

is the boundary conditions that apply to our domain.

Boundary conditions can take many forms

depending on what type of analysis we are conducting,

but they generally serve the same general purpose

and forcing certain conditions to part of the domain

in order to drive the simulations.

In the case of a SIGMA/W simulation, for example,

boundary conditions could include limiting displacements

on the edge of the domain or applying forces and stresses.

Specifying the hydraulic condition

is also a form of boundary condition application.

Appropriately defining the boundary conditions

that apply to a numerical model can be quite challenging

and might be easy to overlook.

Specifying the wrong bunch of conditions for a problem

will cost just as much problem for the overall solution

as would using a batch geometry

or failing to choose the appropriate inputs

for the constitutive laws.

Once the steps one to four I’ve been properly dealt with,

we can move on to solve the numerical analysis.

We call this step, interpretation.

For the user, this is generally the simpler step

of the whole modeling process.

Once the calculations are completed,

GeoStudio will output results,

that can be viewed through contour plots

or line plots for example.

But calculated results in themselves aren’t worth much

if they are not properly verified by a competent user.

This step is crucial in any numerical analysis.

One must have sufficient knowledge and experience

to be able to look at simulation results

and assess if the response

as computed by the software makes sense.

In most cases, the software will input some results.

It is up to the user to understand what these results mean.

And we often say that the numerical modelers

should know the answer they expect

before even launching the software they intent to use.

Having a general idea of how the results should look

will help user on interpret

what the software is telling them.

Finally, this verification step might reveal some flaws

and choices made along the way

from conceptualization to interpretation.

It is quite common then that we will need

to take a step back as we inspect computed results

to rethink our constitutive law choices, for example,

or that particular boundary condition we were unsure about,

if it was appropriate or not.

Critically assessing these choices

will help produce higher quality numerical simulations.

A feature of numerical modeling

that users will most often encounter

is what we call parent-child relationships.

In real life a child inherits certain characteristics

of their parents, which they can in turn pass along

to their own child.

Child’s of the same parents

will share the same characteristics.

Well, the same holds true for GeoStudio analysis.

These characters takes parent analysis

will pass on to child analysis,

will take the form of stressors, pore-water pressure,

accumulator strains, and so on.

This helps create hierarchy and structure

in complex analysis trees where many analysis types

might cohabit and share information.

So for example, in this analysis tree,

all the analysis displayed share the same geometry.

The seepage analysis sits one hierarchy level higher

in the analysis tree than the In-Situ analysis.

As such, the seepage analysis acts as the parent

while the In-Situ analysis is the child.

The In-Situ analysis can then inherits certain features

of the seepage analysis, in this case,

pore-water pressure conditions.

We can define this when defining each analysis.

Important to note here is the limit equilibrium analysis

displayed further down in the analysis tree.

This analysis is also a direct child

of the seepage analysis.

Since it sits at the same level as the In-Situ analysis,

you can call the siblings.

They both have access to the information

provided by the parents, seepage analysis.

Continuing on in the analysis tree,

the stress correction analysis sits one hierarchy level

below the In-Situ analysis.

The In-Situ analysis is then considered

the parent of the stress correction analysis,

and it can pass along information to it.

Finally, that analysis labeled tree, A, B, and C

are all siblings

whose parents is the stress correction analysis.

We are now ready to move on to the practical example

we will analyze to illustrate the various concepts

that were discussed in the webinar.

Cubzac-les-Ponts refers to test embankments

constructed in the 1980s in France

and studied by various researchers.

Two embankments in particular were analyzed.

Embankment A, which was both built fast and high

to purposely result in failure of the underlying soft clay.

Embankment B was constructed slowly

to monitor how pore-water pressure dissipation

would occur in the underlying soft clay.

The goal here is to use GeoStudio Core

to replicate the results.

The construction sequence for both embankments

is shown on this plot.

Embankment A, shown in blue was constructed in four lifts

and reached a maximum height of 4.5 meters

after eight days of construction.

Embarkment B, shown in red was constructed in six lifts

and only reached a maximum height of 2.4 meters

after six days of construction.

Embankment A failed on the ninth day

while Embankment B was monitored for years

after construction stopped.

Here is a cross section of embankment A

where we can see the four lifts of feel in orange,

built on top of a two-meter thick desiccated crust

in yellow.

And the rest of the soil deposit

is a soft clay material in green.

Similarly, here is embankment B’s geometry,

where we can see a smaller total height for the embankment,

as well as the small lifts used.

Since both embankments were constructed on the same site,

we encountered a same desiccated, crust

and soft clay deposits.

To cut computational effort in half,

we can make use of the symmetry of the geometry

by cutting the domain in half

where the summitry axis passes.

We will see later how boundary conditions

where that symmetry axis lies need to be modified

to properly account for the simplification.

The initial hydraulic conditions

are very simple at the test site

with the frantic surface being positioned

at eight meter of elevation,

midway into that desiccated crust.

These conditions apply to both embankments.

Let us now take a look at the analysis tree structure

for each embankment scenario.

For embankment A, the first analysis performed

uses SEEP/W to calculate the pore-water pressure

in the domain.

Next, a SIGMA/W In-Situ analysis is performed

to initiate the stress conditions within the domain.

Note here the father child relationship.

The In-Situ analysis will use a pore-water pressure

defined by the SEEP/W analysis.

Next embankment is constructed using SIGMA/W

consolidation analysis

following the sequence described earlier.

The consolidation analysis take advantage of SIGMA/W’s

fully coupled formulation

where a pore-water pressure migration

is properly simulated as soil consolidation occurs.

The final step to this analysis tree

is a stress-based stability performed in SLOPE/W.

The stresses and pore-water pressure conditions

that exist at the end of stage four of construction sequence

are passed along to the SLOPE/W analysis

to calculate the factor of safety.

A very similar approach is used for embankment B

where initial pore-water pressures

are calculated in SEEP/W,

In-Situ stresses are defined in SIGMA/W,

and the embankment’s constructioned

following the slower-paced sequence laid out earlier.

Once the embankment reaches its maximum height,

at dissipation phase is performed.

And essence, this is just a SIGMA/W conciliation analysis

where no extra load is added

and where we allow the accessible water pressures

to dissipate as time passes.

In this case, the dissipation is allowed to proceed

during 2000 days, which is roughly five and something years.

Finally, a stress-based stability analysis is performed

to verify the factor of safety exactly after

the six stage of construction.

The final aspect of these simulations

that need to be discussed before we jump into GeoStudio

is material definitions

or the choices of constitutive laws if you will.

We will review these choices for each GeoStudio model

in their respective order of appearance

in the analysis tree.

Note that both simulated embankments

share the exact same soil properties.

For the SEEP/W analysis,

the embankment fill is model using a saturated only model

with a large saturated hydraulic conductivity

to promote drainage.

The soft clay is also modeled

using the saturated only model

since we expect this material to remain saturated

throughout the duration of the analysis.

As you will see a few minutes,

the desiccated crust must employ

a saturated/unsaturated model,

as the water table will fluctuate within this layer

during the analysis.

For the SIGMA/W analysis, isotropic elastic materials

are used for both the embankment fill

and desiccated crust as these are quite stiff materials,

and we expect most of the deformations

to occur in the underlying soft clay.

The soft clay is modeled

using the modified cam clay material model.

This constitutive model

is formulated on the classical elastic plastic framework

and exhibits hardening or softening behavior,

depending on the over consolidations state.

Moderately over constellated to normally compressed soils

therefore exhibit accessible water pressures

due to tendency for both elastic

and plastic volumetrics training,

which is an important aspect of soft clay behavior.

Finally, for the SLOPE/W analysis,

Mohr-Coulomb material models are used

so that factors of safety can be calculated

based on the available resistance

defined by the Mohr-Coulomb criteria.

We are in are ready

for the demonstration part of this webinar.

I will open GeoStudio

and walk you through the process of defining and solving

the values analysis required

to study the Cubzac-les-Ponts example.

Here I am in GeoStudio.

The first step to any new project is to create a new file.

Let’s choose to metric letter template

and name the analysis, Cubzac-les-Ponts embankments.

I’m going to add a first 2D geometry to the project,

which will be dedicated to embankment A.

As the geometry will be shared through the values analysis,

I can define it even before I add

any specific analysis to the project.

To make sure I properly track the changes I make,

I will save the file right away.

There are many ways to draw a geometry in GeoStudio.

I already have an Excel workbook

where the coordinates of the geometry points are listed.

I will simply copy paste the X and Y columns

into the defined points window to save time.

Once this is done,

all the points needed to draw the geometry are available

to help me draw the regions

that will define the various materials

and highlight the construction sequence.

By clicking on Draw Regions,

I can easily draw the lower region where the soft clay lies.

Then the upper region where the desiccated crust is.

And finally, each of the four lifts

used to construct the embankment.

It is important here that I split the embankment

into the correct number of lifts,

even if they will share the same material properties

as they will be activated or built, if you will,

in Seequence.

With the geometry now defined,

I can go ahead and add a SEEP/W steady-state analysis

by clicking on Defined Project, then add,

and finally choosing the steady state option

within SEEP/W analysis.

Note that I could change the analysis type to transient

if I wanted to, later on through this menu.

I will name this analysis, initial pore-water pressures.

I will take care of meshing right away

by clicking on the drum mesh properties button.

I can change their mesh layout for the whole analysis

by selecting the entire geometry,

choosing to edit the selected regions

and choosing an appropriate meshing pattern.

Quads and triangle finite elements

are generally a good choice for most use cases.

In the Elements tab, I will apply secondary nodes

as this will provide enhanced precision

for the SIGMA/W analysis to come.

Keep in mind that just as for the general geometry

that is drawn, mission priorities

will also be shared across all the finite element analysis

that use a common geometry.

Given the dimensions of the geometry,

I will specify a global finite element mesh size

of one meter.

I can now inspect the meshing

to make sure it is appropriate.

Given the triangular shape of the embankment,

I could decide to apply triangular elements

only to this part of the geometry.

I’m happy with how the meshing looks now.

As I mentioned earlier,

when discussing the numerical modeling process,

once the simple geometry has been defined,

labeled conceptualization earlier,

and the proper physics have been chosen, in this case,

as steady-state seepage analysis,

I should choose and define the appropriate constitutive laws

for the problem at hand.

To do so, I will go into Define Menu and choose materials.

Let me first define the material properties

for the desiccated crust.

The zone of the analysis with the feature both saturated

and unsaturated flow,

as the free attic surface will pass through it.

And water will seep through it

as the underlying clay consolidates

because of the weight added by the embankment construction.

For these reasons, we will use a saturated/unsaturated

material model here.

This particular model requires two input functions

to calculate water flow, the volumetric water content

and the hydraulic conductivity function.

Both of these parameters will vary

as a function of the matrix suction that develops into soil

as unsaturated flow settles in.

By clicking on the ellipses on the right,

I can define each of these functions.

I will add a new function and use a data point function,

which allows me to estimate

the volumetric water content function

using SEEP/W’s built in simple functions.

In the case of this desiccated crust,

the saturated water content is 0.3

and the material is classified as a silty clay.

By clicking edit data points,

I can view the function in semi log space

and inspect how the volumetric water content

will vary as a function of matrix suction.

As suction increases, water is drawn out of the soil,

and the volumetric water content decreases.

I’m satisfied with this function and name it crust.

I finally choose this newly defined function

through the drop down menu.

In a similar way,

I will not create a hydraulic conductivity function

by clicking on the ellipses on the right

and choose a data point function type.

Again, by clicking on estimate,

I can use SEEP/W’s estimation functions,

which are quite handy,

as we don’t necessarily always have access

to proper laboratory test to define these input functions.

In this case, I will use the Van Genuchten method

and associated with the volumetric water content function

we just defined.

In the case of the crust, a saturated hydraulic conductivity

of 0.008 meter per day is suggested

by the original authors of the Cubzac-les-Ponts study.

The residual water content is 0.05

and a maximum suction of a hundred KPA is sufficient here,

given the small scale of the geometry.

Inspecting the hydraulic conductivity function generated

reveals that as metric suction increases

the hydraulic conductivity decreases,

which is what we desired.

I’m satisfied with this function and name it crust.

And finally, I choose this newly defined function

through the drop down menu.

The definition of the material model

for the desiccated crust is now completed.

I will add another material,

this time defining the underlying soft clay.

As mentioned earlier, since we expect this layer

to remain fully saturated throughout the analysis,

we can use the simple saturated only, maternal model.

The saturated hydraulic conductivity

is set at 0.001 meter per day.

And the associated saturated volumetric water content

is 0.3.

Finally, the embankment fill material

is also submitted using a saturated only material model

for simplicity.

We use a very high saturated hydraulic conductivity

of one meter per day to promote fast drainage

towards the lower parts of the analysis.

The saturated volumetric water content is 0.4.

Now that all the materials have been defined,

I can draw them over the various regions of the geometry,

starting from the bottom to soft clay,

then desiccated crust.

Notice here that I won’t assign the fill material just yet,

as the goal of this first analysis

is simply to establish the hydraulic conditions in the soil

prior to beginning the embarkment construction.

The last step to perform

before we can move on to solving the analysis

is to define appropriate boundary conditions.

In this case,

the boundary conditions are very straightforward.

As the piezometric level was measured

at eight meter of elevation throughout the site.

To represent this, I would go into the Define menu

and choose Boundary conditions.

I will add a new hydraulic boundary condition,

choose the water total headkind,

and define it as a constant head elevation of eight meters.

I can then name this new boundary condition

and assign it in an easy two-spot color.

Once the boundary condition has been created,

I can click on Draw Boundary Conditions

or use the dropdown menu

to apply it to the base of the geometry.

This means that a total head of eight meters

will be applied to each of the point

at the bottom of the analysis.

When launched calculations,

SEEP/W will calculate the corresponding pore-water pressures

everywhere in the domain

as to satisfy the supply boundary condition.

We are now ready to solve the analysis.

Clicking on Start will automatically save the file

and launch the calculations.

Once the analysis is marked as solved,

I can switch to the results view

and inspect the calculated results.

This is the all-important verification step

I alluded to earlier.

By clicking on Draw ISO Surface,

I can draw a continuous line

indicating where water pressure of zero KPA

is in the domain.

This is an easy way

to view where the water table is positioned.

In this case, as we desired,

the free attic surface is located in the desiccated crust.

Using the contours dropdown menu,

I can select the pressure head counter type

to view the water pressure in the entire domain.

And by selecting draw contour labels,

I can click on various contour lines

to inspect the water pressure values in the domain.

In our case, the water pressure is currently indicated

as eight meter high at the base of the analysis.

Our SEEP/W analysis then correctly represents

the initial water conditions we wanted to define.

We can move on to the other parts of the analysis.

The next part of the workflow will be to add

the SIGMA/W analysis to simulate the construction

of each embankment lift.

But before any lift can be added

on top of the existing soil deposit,

the initial stresses must be defined within the domain.

To do so, we’ll go back into the definition view,

click on Define Project

and add a SIGMA/W In-Situ analysis.

By initially selecting the precedent SEEP/W analysis,

when adding the next analysis,

I ensure that the subsequent analysis is created

as a child of the SEEP/W parent.

You can inspect this by simply noticing the L shape

that places the newly added SIGMA/W analysis underneath

the SEEP/W analysis.

You can also see that the initial

pore-water pressures analysis,

is indicated as parent to the In-Situ analysis here,

right underneath the analysis name.

For the In-Situ analysis,

we will use a gravity activation method

where gravity forces will pull downwards on the nodes

and the appropriate horizontal reactions will be calculated

based on the boundary conditions we will define.

The field below indicates that

the pore-water pressure conditions for the analysis

will be inherited from the parents, SEEP/W analysis

just as we wanted.

Notice here are how the materials

that were previously defined in SEEP/W already exist

in SIGMA/W, but the associated colors are great.

This indicates that the materials

are currently not properly defined

for the analysis we want to perform.

By clicking on Define Materials,

I can now edit these materials within SIGMA/W

and choose appropriate constitutive laws for each.

As discussed earlier, both the desiccated crust

and the fill materials will use an isotropic elastic model.

Starting with the desiccated crust,

I must input appropriate values in every field

to make sure the model is properly defined.

Following indications by the authors of the study,

the unit weight is set at 16.5 kilo newtons

per squared meter.

The effective elastic mandalas is supposed constant

at 3000 KPA.

And the effective Poisson’s ratio is set as 0.4.

The response type for this material is strain

as excess pore-water pressure

shouldn’t build up into that site layer.

We did not wish to track void ratio changes

for this material so we can leave it

as it is default at 0.5,

and it will have no influence on the soils response

given the isotropic elastic model used.

Similarly, for the embankment fill representative values

are chosen for each required field

of the isotropic elastic model.

Notice the higher value of unit weight used here,

21 kilo newtons per square meter,

which is typical for fill materials.

Finally, the soft clay material

will use the Modified Cam Clay model.

For this model, void ratio plays an important role

and must be adequately adjusted.

Based on the author’s publication,

a representative value of 2.25

is chosen for the entire clay deposit.

On site the clay was deemed slightly over consolidated.

So, an over a consolidation ratio of 1.4 is used.

Stiffness parameters for the Modified Cam Clay model

required the use of the Lambda and Kappa parameters,

which represent the slope of the normally consolidated

and rebound lines

in a one deconsolidation test respectively.

For the clay at cubzac-les-Ponts,

the following values are representatives.

An effective Poisson’s ratio of 0.4 is used again here.

The friction angle of clay is set at 30 degrees,

which correspond to a critical stress ratio of 1.2

in compression.

Finally, the response type will be on drained

for this material model since we are interested

in monitoring the effect of excess pore-water pressure

buildup in the clay deposit

as the embankment is being built.

The last step to perform before solving the analysis

is to apply proper boundary conditions to the model.

In SIGMA/W, these boundary conditions

often take two different forms,

stress or force boundary conditions,

and displacement boundary conditions.

For this particular study,

there are no stresses or forces to apply on the domain.

However, we need to constrain the formations

in some part of the domain,

which corresponds to displacement boundary conditions.

More specifically,

we want to prevent displacements of the nodes

located at the edge of the geometry

so that they do not sway sideways once gravity is applied

or when the embankment is constructed.

Similarly, we want to prevent displacement of the node

located at the bottom of the geometry

so that gravity has something to push on

when it is activated.

Otherwise, when we are to turn on gravity,

the entire geometry would slide downward

toward the bottom of the screen.

To apply these displacement boundary conditions,

I will click on the Draw Boundary Conditions button

and assign a fixed X to the edges of the analysis.

A fixed X boundary condition

is simply a displacement boundary condition

that states that displacement in the X direction

should remain at zero for every node long,

which is boundary condition is applied.

Selecting the nodes on the edge of the geometry

will apply the chosen boundary condition.

Similarly, I will apply a fixed XY boundary condition

to the bottom of the geometry.

This time supports in both directions are drawn at the nodes

indicating that displacements will be permitted

at both directions during the simulation,

just as we required.

We have now probably defined a boundary conditions

for the In-Situ SIGMA/W analysis

and are ready to solve the analysis.

In the Solve Manager window,

I can untake the initial SEEP/W analysis

as I don’t want to solve it again.

Once I click on Solve, gravity is applied at the nodes

and resulting stresses are calculated.

Once calculations are completed,

I can switch into Results View and inspect the results.

I can draw contours of the total vertical stress

to view the stress distribution.

I can also plot the total vertical stress,

the effective vertical stress and the pore-water pressure

on a vertical line drawn

from the two of the future embankment.

I can view these three stress components together

by shift the king, each injured or plot-defined.

We can see here that suction develops

in the first meter of the disputed crust,

which increases the effective vertical stress

compared to the total vertical stress.

These results satisfy me,

so I can move on to constructing the embankment.

As I showed earlier,

the first embankment lift was constructed

and left in place for four days

before another lift was added.

During these four days, the accessible water pressure

that had instantly developed in the soft clay deposit

was allowed to consolidate.

To simulate this behavior,

I will add a SIGMA/W consolidation analysis

to the analysis tree.

I will go back into definition view,

and click on Define Project.

Once the In-Situ analysis is selected,

I will go into add

and choose a SIGMA/W consolidation analysis.

By having selected the In-Situ analysis

prior to adding this new analysis,

I made sure that the consolidation analysis

was a child of the In-Situ parent.

Note that the initial stress and pore-water pressure

will come from the parent analysis

as indicated by this drop down menu.

And we’ll make sure that the reset displacement and strains,

and reset state variables check boxes are checked

because I want to discard any strains

that might have arisen during the In-Situ analysis.

These strains took place in the geological history

of the soil deposit.

They have already happened

before the embankment construction began.

So I don’t want to account for them moving forward.

Next, I would go into the Time tab

and adjust the duration to four days

to reflect the construction sequence.

I will also adjust the number of calculation steps to four

so that I record the behavior everyday.

I will add the first embankment lift

by going into Draw Materials

and simply applying the fill material

to the first lift region.

When solving the analysis,

the materials weight will be activated

and the appropriate pore-water pressure response

will be generated in the on drain soft clay.

You will notice that the fixed displacement

boundary conditions that existed in the parent

In-Situ analysis already exist in this new analysis.

This is so specifically

because of the parent/child relationship

these two analysers entertain.

I could however, changed the boundary conditions

in the child and indices

without affecting the parent if needed.

And in fact, this is what I’m going to do right here.

I will add a drainage type boundary conditions

to promote drainage toward the surface

at junction of the desiccated crust and the embankment.

This way, excess pore-water pressures

that develop in the soft clay,

will be able to migrate toward the surface.

I will also add back the eight meter,

total head boundary condition to the bottom of the analysis

as this condition will still hold true

during the complete duration of the construction sequence.

Now that the materials were applied

and the boundary conditions were properly adjusted,

I can solve the analysis.

Once the computations are over, I can go into Results View

and inspect the results.

Plotting the pore-water pressure contours

highlights how accessible water pressures developed

once the first lift embankment was applied

on top of the desiccated clay.

By navigating through the calculation steps

in the steps window,

I can first select to view the pore-water pressure

before the first lift was added.

Then I can set a following days

to see the accessible water pressure.

Plotting the pore-water pressures

and multi selecting all the calculations steps

also clearly shows that pore-water pressure increased.

The red line indicates the starting pore-water pressure.

If time was allowed to tend toward infinity,

the pore-water pressure profile

would fall back on the red line

and these dissipated pour water pressures

would translate into consolidation deformations,

but instead of allowing the pore-water pressure

to dissipate further,

another leaf of embankment will be added

on the fifth day of construction.

To add the second lift,

I will proceed just as I did for the first lift.

returning into definition view, clicking on Define Project

and adding a SIGMA/W consolidation analysis

as a child of the first stage of construction.

This time, I don’t want to check the reset displacement

and strain and reset state variable check boxes

As I want to keep accounting

for the added strains produced by the construction sequence.

In the Time tab, I will adjust the duration to two days

and a number of steps to two

to properly reflect the construction sequence.

As you’ll recall, the second embankment lift was added

and maintained in place for two days

before the third lift was placed.

By going into Draw Materials, I can add the second lift.

The boundary conditions remain exactly the same as before

for this analysis as we are simply adding more weight

to the embankment.

I can go ahead and solve this analysis

and inspect the additional accessible water pressures

that were generated as this new lift was placed

on top of the first one.

Let me go ahead and quickly add the third and fourth lifts

to the embankment using the exact same procedure.

Both lifts were constructed in a single day

before the next lift was placed.

Inspecting the results after the fourth lift has been built,

shows how excess pore-water pressures

have continued to build up in the soft clay layer.

By plotting the effective vertical stress profile

we can see how the effective stresses are being reduced

by the increasing excess pore-water.

This will affect sheer resistance that can be mobilized

and will result in large deformations being generated.

Let us look at these right now.

I will begin by plotting surface settlement

which correspond to vertical displacement

in the wide Y direction along the embankment

at the top of the desiccated crust layer.

As expected settlements are smaller

toward the left side of the embankment,

as the height is smaller.

And toward the middle of settlements reach 80.5 centimeters.

Another interesting deformation plot to look at

is the lateral displacement at the toe of the embankment.

The toe of the embankment itself moved toward the right

by more than 17 centimeters.

Another way to appreciate these deformations

is to overlay XY displacement vectors

on top of the geometry.

To do this, I click on the Draw Vectors button

and toggle and on the XY displacement vectors.

We can now see how the entire right side of the embankment

deforms in a circular motion toward the right side.

Seeing this deformation pattern,

one wonders if stability of the embankment

is currently compromised.

To verify this, let us add a SLOPE/W stability analysis

to this analysis tree.

As before, to add this new analysis,

I will go back into definitions view

and click on the Define Project.

I will add a SLOPE/W, SIGMA/W stress analysis.

This type of analysis will use the stresses

passed along by the parent’s SIGMA/W analysis

and perform stability analysis based on these stresses.

Compared to a traditional SLOPE/W limit equilibrium,

the finite element slope stability analysis

doesn’t need to iterate to find enters life stresses

that will ensure the factor of safety

is the same in all the slices.

Instead as the stresses are known

the resistance is directly compared to the substation

and factor of safety is locally computed in every slice.

The overall safety factor for a slip surface

is determined by integrating the share resistance

and mobilized chair along the entire slip surface.

The slip surface direction of movement

will be from left to right,

and I will use the entry and exit method

to generate the trials grip surfaces.

I will also toggle on the slip surface optimization option.

As we define the slope stability analysis,

notice how the materials are now grayed out.

This again, indicates that our materials

are not properly defined for the analysis.

By going into Define Materials,

I can see no resistance model is currently used.

The SIGMA/W material models differ

from what we need for stability analysis.

So I must make sure to properly define the materials

here again.

Every material we have,

we’ll use a Mohr-Coulomb material model.

The soft clay will use equation of zero KPA

and a fictional angle of 30 degrees.

And notice that the unit weight was already defined here

as we had defined it previously in the SIGMA/W analysis.

The embankment field will use zero cohesion

and a fictional of 35 degrees.

An finally, the desiccated crust

will use a zero cohesion,

as well as a friction angle of 30 degrees.

Before solving the analysis

I need to define where to slip surface

entry and exit points will be.

This layout that I’ve just drawn will produce 10 increments

of entry and exit points as well as 10 radiuses

to be studied for each pair of entry and exit points.

Once I hit the Start button,

all the trials slip surfaces are analyzed

and a critical slip surface is shown.

The slip surface reaches into the soft clay layer

where excess pore-water pressure had built

during the embankment construction.

The minimum factor of safety is computed as 1.09.

And from this slip surface SLOPE/W calculated

and optimized slip surface,

where the fact of safety was decreased further down to 1.03,

by optimizing the sleep surface geometry.

At this stage of the embankment construction sequence,

the stability is marginal.

This correctly reflects the situation described

in the case study,

as the embankment failed on the ninth day of construction.

By plotting the sheer resistance and the sheer marbleized

along the slip surface, I can see how both of these vary.

For the slices that are located

toward the top of the embankment,

their share mobilized is generally higher than resistance

and conversely, toward the toe of the embankment.

This type of plot neatly shows where resistance is too low

along the slip surface.

This concludes the analysis

for the first embankment geometry.

This embankment was built quickly

so that the embankment would fail.

We saw that the excess pore-water pressure

that developed in the soft clay layer

during the embankment construction was sufficient

to bring the overall factor of safety close to one,

indicating that the stability was marginal.

The second embankment was constructed more slowly,

and to a lesser height than embankment A.

Since the geometry of the second embankment is different,

I will need to create as distinct geometry.

I can do this within the same file

to keep both analysis together

and easily use the same materials and boundary conditions

that I have already defined.

To the new geometry, I will go into definition view,

.click on Define Project,

select the first element of the overall hierarchy

and add the 2D geometry.

Let us call this one embankment B.

Similar to how I worked for the first embankment geometry

I will go into defined points to paste the geometry points

I already had on hand from an Excel file.

I will finish defining the geometry by drawing the regions

corresponding to the materials that will be used later on.

Notice here, as we saw earlier,

we take advantage of the symmetry of the geometry

by only drawing half of the embankment.

I will now create the SEEP/W analysis

to initiate the water and seepage conditions in the domain

and also build the embankment lifts using SIGMA/W

just like I did for the first embankment.

The steps are mostly identical.

So I will speed up the process in the interest time.

Here, I adjust the mesh size and shape.

I draw the materials to the regions.

The materials are the same as for embankment A.

A I now apply the total head hydraulic boundary conditions

at the bottom of the domain, and solve.

I now create the In-Situ SIGMA/W analysis

to initiate the stresses.

I applied a fixed displacement boundary conditions

to the bottom and sides.

And notice here that I applied the fixed X

boundary condition to the entire left side of the geometry.

Even the lift regions that are currently empty.

These will not affect the In-Situ analysis,

but will affect the next SIGMA/W consolidation analysis.

I could have drawn each portion

when the lifts are individually placed,

but this saves a bit of time.

I now solve the analysis

and verify that distresses are appropriate.

Next I add the first lift of the embankment

using a SIGMA/W consolidation analysis.

I apply the material to the first lift

and apply the hydrate boundary conditions

just as I did previously.

I will add the remaining lifts

as separated SIGMA/W consolidation analyses

and inspect the results.

Plotting the pore-water pressure

under the central line of embankment

shows that the load created

by the construction of the embankment

created excess pore-water pressure.

The red line is the profile of the pore-water pressure

before the construction began.

I can also plot the surface settlement

along the entire length of the geometry

at the top of the desiccated crust.

Settlements are currently reaching

a maximum of 8.7 centimeters under the embankment.

We can also see an uplift near the embankment toe

reaching about 4.5 centimeters.

Finally, literal displacements

show that the toe of the embankment

is moving toward the right, which can also be seen

by drawing the XY displacement vectors.

At this point, it is interesting to perform

a stability analysis to verify how impactful

this slower construction sequence

and lesser embankment height was

compared to the embankment.

Again, I add a SLOPE/W stress-based stability analysis

at the tail of the analysis tree.

This time, the factor of safety is around 1.5,

which is quite a lot higher than previously,

and would not suggest stability issues.

This result aligns with what we expected.

The last analysis we will perform here

is a dissipation analysis.

In a sense, a dissipation analysis

is just a standard consolidation analysis,

but in which no additional load is added.

The goal is simply to let time pass

as excess pore-water pressure dissipates

and the soil consolidates.

To perform this analysis,

I will add another SIGMA/W consolidation analysis

to the analysis tree.

Notice that when going into Definition View

and then define project,

I will select stage six of construction

as this is the parent to which I want to add a child,

not the slope stability analysis.

In the Time tab, I will adjust the duration to 2000 days

and I will increase the number of steps to 50.

To make sure I have enough resolution in the earlier stages

of the analysis where pore-water pressure

will vary more quickly,

I will toogle the steps in to increase exponentially

and adjust the initial increment size to one day.

Finally, I will save the analysis results every 10 steps

as recording all the calculation steps

will provide more data than I really need,

including fewer safe steps will accelerate computations.

In the window on the right,

I can see the time increments as well as the safe points

that will be recorded.

I can now solve the dissipation analysis.

There are no further steps to take care of

as the boundary conditions are remained the same as before.

Once the analysis is solved,

I can, once again, inspect the results.

Plotting the pore-water pressure underneath the embankment

shows how the excess pore-water pressure

that had been generated by the embankment construction

has now mostly been dissipated after 2000 days.

The excess pore-water pressure dissipation we see

is synonymous with soil consolidation.

Plotting the surface settlement during these 5.5 years

or 2000 days reveals that vertical deformation

in the middle of the embankment

went from 11 centimeters to almost 55 centimeters.

This is the direct result of the consolidation

of the soft clay that took place

as excessive pore-water pressure were being dissipated.

This concludes the demonstration portion of the webinar.

In the interest of time, I have not shown comparison plots

between the simulated results in GeoStudio

and results from the original Cubzac-les-Ponts study.

Interested users should download the website example,

which contains both the GeoStudio file for you to review,

as well as a PDF with detailed comments

about the case study.

So this concludes the October edition

of our GeoStudio Tech Talk webinars series.

The webinar focused on GeoStudio Core,

the group of products featuring SLOPE/W, SEEP/W,

and SIGMA/W.

We saw how each product fulfills its own role

through an integrated solution approach.

We also reviewed how a thorough numerical modeling process

should be conducted.

And six important steps were laid out.

Conceptualizing a complex problem

into a manageable, simple model.

Choosing the appropriate physics

that should be taken into account.

Choosing and prioritizing the appropriate

constitutive of laws that correctly represent the soils

we want to model.

Applying boundary conditions

to drive the analysis or impose appropriate constraints.

Resolving the analysis

once the model is correctly defined

and interpreting the results.

And finally verifying the results

to make sure they appropriately represent

what we intended to model.

Each of these steps requires reflection

and might bring us to reconsider some choices

we made earlier in the modeling process.

We have also discussed what parent-child relationships are

and how the help structure a practical hierarchy

within analysis tree.

The final part of the webinar was dedicated to building

the Cubzac-les-Ponts example,

where to construction sequence of two embankment

built on soft clay is simulated

using the GeoStudio Core products.

We saw both the failure of embankment A

and the longterm behavior of embankment B

could be simulated appropriately in GeoStudio.

Don’t forget that you can download the example

from our website

if you want to give this workload a try by yourself.

If you’d like some new features and capabilities

added in GeoStudio Core, don’t hesitate to make suggestions

by submitting support requests.

Finally, don’t forget that GeoStudio learning content

is available for free through Seequence website.

We offer a three courses,

part of our learning management system.

GeoStudio basics, SLOPE/W fundamentals,

and SEEP/W fundamentals.

Head over to,

create your Seequent ID using your company email address

and take advantage of these incredible

learning resources for free.

We have now reached the end of this webinar.

A recording of the webinar will be available to view online.

Please take the time to complete the short survey

that appears on your screen

so we know what types of webinars

you are interested in attending in the future.

Thank you very much for joining us

and have a great rest of your day.