Oedometer Testing - Soil Analysis

[MatthewMansfield]

Hello all

I was wondering if any had a background or understanding on soil settlement/consolidation testing specifically oedometer testing.

My understanding is that we simply measure displacement vs time however I have been given the following data:-

https://files.engineering.com/getfile.aspx?folder=2937b684-c8f6-4bbd-a9aa-03844b30eda5&file=Data.png

I don't understand the Dial Reading values which are shown in mm.

I would interpret this data as at 0 min the displacement was 7.82mm, at say 4 min the displacement is 6.78mm - but why are the values for Dial Readings getting smaller I would have thought that as the soil compressed then the displacement values would get larger.

Can anyone help shed any light?

Thank you.

 

[r13]

Expansive soil? Just guessing.

 

[Eric C.]

My first guess would be that the indicator is set up such that displacement at time(x)= dial reading at time(0) minus dial reading at time(x). However, I believe I would check with the lab to confirm this.

 

[Haris Parikh]

Generally, Oedometer tests are performed by applying various loads to a soil sample and grading the deformation response. The results from these tests are used to predict how the soil in the field will deform in response to an advance in effective stress.

 

[r13]

I think Haris comment makes sense. T diagram below could be the case. Note the changes in volume are measured in each stage at varies time interval, and the change decreases in succession compressions.