You Can’t Spell “Studying” Without “Student” and “Dying”

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Finals time is now here. For engineers this is a very interesting part of life. It mainly includes many students getting together at school to panic and talk about their hatred for specific classes, group projects, professors and how the air conditioner is not run in our building on the weekends. I currently have a few finals to study for and 1 project left. I was one of five students in my Technical Communications class to have an ‘A’ and not have to take the final. The only girl I might add :]

I am moving along slowly but feeling confident that I will not only pass all of my classes but score high marks in them! I do have one presentation to give on my group analysis of soils and a footing design which I am NOT looking forward too and it is taking up all of my time. Ugh.

On a lighter note this past week I went on my very first construction site! I got to wear a hard hat and all of the protective gear and see different parts of the job in progress.

Cal Poly Pomona is building a new business development with three buildings to house offices, classrooms and lecture halls. Below are some pictures of the foundations and rebar going in for the footings. Some compaction devices are shown as well. The length of proposed footing is large as well as being about 20 ft deep. The site lies directly North of the San Jose Fault. It’s interesting because when designing buildings the fault can change so much on a site including groundwater table and soil layers. A building should always be on either side of the fault and not cross it perpendicular due to shifts in the plates on either side of the fault. Check out the pictures below while i get back to studying! There is a fun one of my group and I and the end too! GO TEAM BLUE! :]]

-Diane  ❤

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Shear Stress in Soils

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I have a Geotechnical Lab class and it is my last class in the geotech series, yay! We’re testing all the interesting things I’ve been learning all year! We just finished the direct shear strength testing where we used a shear testing device like this one below to apply normal stress that would be applied by a footing to see what kind of shear would be created.

If a building were to fail under direct shear it would look something like the picture below. The area of soil that should be tested for shear is going to be below the footing about the same distance down from the footing that the footing is from the surface of the soil.

The results were predictable for the sample I had. It was a loose sand and compacted nicely as well as withstanding a large amount of shear stress. For the test a small ring sample was inserted into the direct shear machine, compressed and sheared. This is what a typical sample would look like after the test is completed.

Below is a graph taken from the computer calculated results applying 1000 lb of normal force. The graph shows the shear stress vs shear displacement and axial displacement vs shear displacement. This test was done on 3 different undisturbed samples of the same soil.


Three samples were tested and under different normal loadings which would simulate different applied footing loads and direct shear was measure for all of them. Once these were tested I should be able to construct a Mohr-Coulomb Failure envelope slope for normal and shear stress. Max shear and cohesion will be obtainable from the graph. It is also always key to note cohesion is generally apparent unless chemical properties change or cementation occurs.

Only a couple more weeks of class and the quarter will be done! Only to have a week off before starting summer school! Wahoo! Anyways, fluid mechanics is calling my name and I have a midterm next Wednesday. Hopefully I will master Reynolds Transport Theorem. Details to come soon!

xoxo

Diane