When it comes to construction, the geotechnical and materials engineering graduate program focuses on what’s below the surface, not to what’s above it.

“Before you design everything on the structure because you usually see the structures on top of the ground,” said Mohamma Fotouhi, graduate in civil, construction and environmental engineering.

The program, which consists of both students and faculty, takes a look at soil behavior and how natural phenomena such as earthquakes can affect these infrastructures.

“A structural engineer will use materials like concrete and steel to build with, and those materials are well defined and there have been a lot of tests to predict how they’ll behave but with soil,” said Jacob Phipps, graduate in civil, construction and environmental engineering. “It’s widely variable and you can’t see it below the ground surface.” 

“In order to characterize the soil in order to build with it, there has to be a lot of testing to define how you think it’s going to behave under an earthquake load or a load from a structure,” Phipps said.

Soil is essential for earthquake resistance. Whatever is built, the foundation is soil, said Chris Williams, professor of civil, construction and environmental engineering.

“A lot of graduate students are working on earthquake problems and I think right now it’s because people are more aware that our structures — like bridges — may have not been designed adequately to withhold an earthquake,” Phipps said.

With soil being the crucial foundation for any construction, several factors need to be considered — one of them being the amount of load placed onto the soils.

“Geotechnical engineering deals with the engineering behavior of soils,” said Vern Schaefer, professor of civil, construction and environmental engineering. “When you put loads on them — build a building, a road, an earth dam or construct an earth dam out of soil — you build a retaining wall. All of these things put a load on the soil, and the soil is like any other material — if you load it too much, it deforms and desettles.”

A strong soil could be determined by the type of sediment — the size of the soil particles and the lack of an abundance in water.

“Another indicator would be the cementation between particles,” Fotouhi said. “With clays, there’s lots of cohesive materials to put everything together.”

“You cannot easily define what’s the strength in the sediment,” Fotouhi said. “You have to do many tests, consider many factors to roughly predict if the soil is strong enough and after predicting you have to do the test again during the construction and monitor everything enough for the construction period and after that during the life period of construction.”

“The soil in Iowa may be good for crops, but the issue is the residence soils we have don’t provide good structural support for our highways,” Williams said.

“With roads, first you have to compact the soil because it’s not acceptable to have some bump in the road and destroy the design,” Fotouhi said.

An issue even more adverse, however, would be the abundance of water.

“Soils are a really good material when dry,” Schaefer said. “When they get wet, we tend to have problems with them. Almost every engineering problem that we have with soils relates to, ‘What is the relationship of water to it? Does it have too much water? Not enough water?’ So what happens if you dry a soil out? It cracks and when water comes in it creates a lot more pathways for water.” 

When constructing anything, it’s important to assess any water conditions in the soil.

“If there’s bad water conditions or if there’s a really soft or weak soil. Then that information will tell us how to design a foundation if we want to build on that site,” Phipps said.

Various soils such as expansive soils can expand drastically when saturated. This can cause substantial harm to infrastructures.

“What happens is expansive soil sucks in water,” Schaefer said. “These soils can hold two to three times their weight in water. But when they do that, they expand and those expansion pressures are very strong. They can actually lift a house up and deform a house leading to cracking in the wall board, misalignment of windows and doors so that they can’t open, so expansive soils are a problem.” 

Because highways and buildings won’t stop being constructed, Geotech won’t stop its research in regards to the soil that underlies everything.

“The role of an engineer is to design something considering the money and finances,” Fotouhi said. “So in geotechnical engineering it’s the same thing. You should know the strengths of the soil, the sediment, everything about the ground.”