By Keith Plemmons,
PhD, PE, PMP
Civil and Environmental Engineering Department
College laboratories are normally thought of as smelly
and musty places with students shuffling about quietly in their
lab coats and goggles, watching mold grow or dissecting frogs.
This is not the case in The Citadel's Outdoor Soils Lab (OSL).
Located outdoors with sunshine, fresh air, overlooking the Ashley
River in an atmosphere that is sometimes very noisy, the OSL is
busy with students wearing sunglasses, hard hats and hearing protection.
Despite the differences, the objective remains the same—students
learn the practical application of basic concepts and theories.
students record blow counts and gather around Greg Canivan
to watch the pile driving and to observe his PDA analysis.
The OSL is part of our Civil and Environmental Engineering
(CEE) program and provides senior geotechnical engineering students
with something they would not normally receive in an undergraduate
classroom or laboratory—field experience. To get this field
experience, I brought the students in my geotechnical class together
with local engineering firms and pile-driving companies to observe
and participate in field investigations and pile driving.
Canivan of S&ME demonstrates how strain gages and accelerometers
are attached to a steel H-pile.
As Cadet Jonathan Black commented, "The outdoor soils lab
provided invaluable experience by reinforcing topics that were
previously only seen in the classroom."
Located on The Citadel campus, the OSL provides an opportunity
for undergraduate CEE students to develop a better understanding
of the subjects taught in the classroom. Using hands-on experiences
and field demonstrations, the class observes how basic geotechnical
concepts apply to everyday practice.
"You can learn anything in the classroom, but seeing it
in the field makes it real," said Cadet Joseph Adams.
Modeled after the engineering and construction process,
the field investigation took place last January, the data analysis
and the laboratory tests were performed in February and March
and the construction occurred in April.
McCormick from Pile Drivers Inc. discusses pile driving fundamentals
with two cadets.
In January, two local engineering and testing companies
set up four demonstration stations. At station one, Soil Consultants
Inc. performed a split-spoon sample soil boring with Standard
Penetration Tests at five-foot intervals. In addition, several
undisturbed Shelby Tube samples were obtained at various depths.
At this station, students were instructed on the drilling operations,
observed drilling and sampling procedures, and obtained soil samples
to be tested as part of their soils lab.
At stations two, three and four, S&ME Inc. provided demonstrations
of the Seismic Cone Penetration Test (SCPT) rig, a Troxler nuclear
density testing device, and a speedy moisture tester, respectively.
After going through all four stations and to be released from
the lab, each student had to walk me through each station, explaining
the procedures, application of theory, materials used and other
Less than three months after the field investigation, the
students found themselves back in the OSL watching Pile Drivers
Inc. set up and drive an 80-foot HP 10x42 pile and S&ME Inc. perform
Pile Driving Analysis (PDA) procedures. This time they had a personal
interest in the outcome. Each student had used the soil profile
from the OSL in January to calculate the ultimate bearing capacity
of the pile and their results entered into a contest, with the
closest answer winning $10 and a case of soft drinks.
Before the pile driving began, the students gathered around
the pile driving rig to be instructed on its components and operation.
Also, they were able to watch Greg Canivan from S&ME install the
strain gages and accelerometers on the pile and explain how they
worked. During the pile driving, two of the students, Joshua Roberson
and Andrew Krisel, volunteered to record blow counts, while the
remainder of the class watched Greg analyze the PDA data.
After driving the pile a total of 76 feet and with 30 of
those feet driven into the Cooper Marl, the operation halted for
20 minutes to let the pile gain strength. Restriking the pile
and analyzing the data, the students were surprised to learn the
pile capacity increased from 35 tons to approximately 85 tons.
Though no surprise to the experts, the students thought this gain
in capacity was magic.
The Cooper Marl is a thick, uniform layer of highly plastic
clay and the primary deep foundation bearing stratum for the Charleston,
S.C., area of the United States. Calcareous soil in nature, it
is composed of the skeletal remains of microscopic sea organisms,
quartz sand, phosphate and clay minerals. Characterized by a standard
penetration test N-value range of 10 to 20, it is stiff to very
stiff in consistency, olive in color, with a sandy-clay to sandy-silt
composition. Open in structure and high in moisture content (40
to 60 percent), the Cooper Marl produces driven piles with relatively
small driving resistance. But shortly after driving and as pore
pressures dissipate, the capacity gain with respect to time is
substantial and yields an economical foundation design. These
characteristics of the Cooper Marl account for most of the magic.
"What began as an idea about moving students from theory
and the textbook to give them practical field experience has come
to fruition. This is where learning happens. Now we have Outdoor
Soils Lab where students can experience important aspects of fieldwork
and the process of driving piles. This is a meaningful addition
to our program. I want to thank those companies involved for their
contribution in helping make this possible," said Dennis Fallon,
Dean of the School of Engineering.
The OSL experience resulted from collaboration among The
Citadel, the South Carolina Chapter of PDCA, engineering and testing
firms, pile driving companies, and material suppliers. Together
they worked to educate the next generation of engineers.
"The outdoor soils lab was the capstone for our geotechnical
classes as it brought the theories and testing procedures to life,"
said Cadet Jae Mattox.
Author's Note: Last year was the first year for
the OSL and it proved very instructive to put companies and students
together. In the future, we hope to make additions to our OSL
and to demonstrate other aspects of what it means to be a geotechnical
engineer. We want to extend the intellectual excitement from the
classroom to the field. Being part of a field investigation and
developing some idea of what it takes to engineer and construct
a driven foundation are experiences that students will long remember.
Hopefully these experiences will help them make sound and economical
engineering decisions regarding foundation options.