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(dramatic music)

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(logo whooshing)
(text whooshing)

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- [Narrator] Soil improvement is crucial

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for building retaining
walls and embankments

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on areas with compressible soils.

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However, selecting the right technology

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to achieve this can be challenging.

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The University of Texas at San Antonio

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and the Texas Department of Transportation

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researched construction methods,

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such as preloading and lightweight fills,

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to compile data and analyze
time and cost for crews

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based on settlement criteria.

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- Consolidation settlement
is when you place a load

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on a soil that's compressible,
it'll consolidate.

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So, that load will actually
produce a downward settlement

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in the material that's sitting
underneath that embankment

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or that retaining wall.

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- So, to stop this issue,

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typically we have to
make the soil stronger

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before we build an
embankment on top of it.

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So, the question we ask ourself is

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how strong we need to make our soil

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to make a (indistinct) settlement

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between the bridge and
the roadway acceptable.

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Bridges generally is supported

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by strong concrete foundation,

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which will settle less
during the service life.

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And on the other hand, a roadway
is supported by embankment,

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which is typically built
directly on top of soil.

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Soil gonna settle more.

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- Settlement, especially
along our coastal regions,

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is a fairly prolific issue.

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But it's one that, you know,

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when spread over a large area,
can be a costly one as well.

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So, it becomes very important for us

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to be able to characterize the issue

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and do a better job of determining

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when it is a problem and when it isn't,

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because it has very
heavy cost implications.

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So, part of the project was to
be able to kind of determine

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what the general state of
practice was across the country,

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to be able to determine what
settlement criteria to pick,

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because from that standpoint,

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it's a serviceability check.

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So, it's something that,

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you know, whenever you see like a bump

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at the beginning of the
bridge or something like that,

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those are the types of things
that we're trying to avoid.

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- This project has a
potential of implementation

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because we develop a certain
design procedure and guideline.

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So, to have this guideline

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and design procedure
implemented across the state,

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and we need to gather
information for the users

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across the state and then get feedback

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and then improve the procedure

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to better fit into the
(indistinct) practice.

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- From our standpoint, the
next implementation step is

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to work on setting policy.

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So, our group does set design policy

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for geotechnical structures.

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And so, this equips us to
better make better decisions

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with regards to, you know,

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what items we need to add,

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and also kind of equips
us to help consultants

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and help ourselves make decisions on how

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to implement settlement
mitigation measures,

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and also whether or not they need

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to be included in a given project,

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how it would end up affecting
our structures to kind

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of avoid, you know, having to go back

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and do, you know, additional
maintenance after the fact.

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- [Narrator] For more information

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and to find the publication
for this project,

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please visit the TxDOT Research Library

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at the link shown below.