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- [Narrator] Soil improvement is crucial
for building retaining walls and embankments
on areas with compressible soils.
However, selecting the right technology
to achieve this can be challenging.
The University of Texas at San Antonio
and the Texas Department of Transportation
researched construction methods,
such as preloading and lightweight fills,
to compile data and analyze time and cost for crews
based on settlement criteria.
- Consolidation settlement is when you place a load
on a soil that's compressible, it'll consolidate.
So, that load will actually produce a downward settlement
in the material that's sitting underneath that embankment
or that retaining wall.
- So, to stop this issue,
typically we have to make the soil stronger
before we build an embankment on top of it.
So, the question we ask ourself is
how strong we need to make our soil
to make a (indistinct) settlement
between the bridge and the roadway acceptable.
Bridges generally is supported
by strong concrete foundation,
which will settle less during the service life.
And on the other hand, a roadway is supported by embankment,
which is typically built directly on top of soil.
Soil gonna settle more.
- Settlement, especially along our coastal regions,
is a fairly prolific issue.
But it's one that, you know,
when spread over a large area, can be a costly one as well.
So, it becomes very important for us
to be able to characterize the issue
and do a better job of determining
when it is a problem and when it isn't,
because it has very heavy cost implications.
So, part of the project was to be able to kind of determine
what the general state of practice was across the country,
to be able to determine what settlement criteria to pick,
because from that standpoint,
it's a serviceability check.
So, it's something that,
you know, whenever you see like a bump
at the beginning of the bridge or something like that,
those are the types of things that we're trying to avoid.
- This project has a potential of implementation
because we develop a certain design procedure and guideline.
So, to have this guideline
and design procedure implemented across the state,
and we need to gather information for the users
across the state and then get feedback
and then improve the procedure
to better fit into the (indistinct) practice.
- From our standpoint, the next implementation step is
to work on setting policy.
So, our group does set design policy
for geotechnical structures.
And so, this equips us to better make better decisions
with regards to, you know,
what items we need to add,
and also kind of equips us to help consultants
and help ourselves make decisions on how
to implement settlement mitigation measures,
and also whether or not they need
to be included in a given project,
how it would end up affecting our structures to kind
of avoid, you know, having to go back
and do, you know, additional maintenance after the fact.
- [Narrator] For more information
and to find the publication for this project,
please visit the TxDOT Research Library
at the link shown below.