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- [Narrator] Core sampling has been the way road builders
and bridge engineers determine
the subsurface soils on a planned project.
However, the information is not complete
and the core samples often miss
a drastic change in soil conditions between the samples.
The misdiagnosis can be costly.
So researchers with the University of Texas at Arlington
have investigated a new technique
called Electrical Resistivity Imaging
to help fill in the gaps.
- Texas faces many cost overruns and change orders.
And many of these costs overruns and change orders
of project, are due to
lack of sufficient subsurface information.
- For any infrastructure project, a road or a bridge.
Before we can design it, we have to figure out
what's going on with the ground underneath it
and traditionally we would drill,
we would get borings where we drill down,
either run tests in situ or sample the soil,
take it back to the lab and measure engineering properties.
It's fairly expensive.
There's only so many borings,
you can do for any given job site.
- It's kind of a hit or miss approach
and so we may be missing a very critical
element of what's underneath,
and if we have missed it during our investigation,
would definitely have to pay for that during
the building of our infrastructure, or we have to pay,
We're basically deferring that to when it,
when that structure fails.
- [Trenton] This research project enables Tex Dot
to do more with a geophysical method
called electrical resistivity imaging.
- [Moshen] What you get from these technologies
is a bunch of numbers and images,
which is telling you what the electrical resistivity
in the ground is.
But it doesn't relate that information to soil.
So what we did is, we basically visited five districts.
We collected soil samples and those soil samples,
we brought all of them to our labs.
In our lab, we did lots of testing,
electrical resistivity testing,
and many of the geo-technical, basically, testing.
Then, using this information, we created a manual
and in that manual, we explained
that how electrical resistivity should be done.
And we included equations and charts
that they are establishing relationships between
electrical resistivity results and geo-technical parameters
that we use in our designs.
We also included information of how to interpret
electrical resistivity images.
- During our planning phase,
we have to go through our environmental process
and schematic development that includes
alternative analysis for at least two or three alternatives.
And this technology will give us
preliminary information on what's underneath.
Under the footprint of each alternative.
In that way, we'll be able to decide
if some of the alternatives are better than the others.
- We're basically bringing subsurface site investigations
into the 21st century.
We're very good at leveraging the traditional methods
of site exploration, but now we are leveraging
more advanced methods.
- [Narrator] For more information,
and to find the publications for this project,
please visit the Tex Dot research library
at the link shown below.