Anyone made their own oedometer 1

[inaz]

I hear it used to be fairly common for geotechs to have a machine shop make their consolidation/swell machines.

I have a machine shop next door and thought I might try it. Has anybody done this and/or have pictures they can share??

The basic concept seems easy enough, but I'm not sure of some of the specifics. The ones I'm used to have a moment arm that starts at the sample and extends out to the weight. I would think it would have to be hinged behind the sample, and at some point along the arm would press down on the sample cell. I'm not sure how to calc the moment arm with a weight-to-hinge distance and a weight-to-sample cell distance.

 

[oldestguy]

Yup, I've done just that.

Yes some sort of hinge at the sample is needed, but not fancy.

A ball bearing resting in a depression also works.

You may need some counter weight, to balance out the weight of the long arm at low loadings.

 

[MRM]

I wonder if anyone has ever experimented with a miniature oedometer, i.e. an oedometer that can accept a metal "sleeve" of clay from a split barrel sampler. The sleeve would be cut with a band saw, say, 3/8" inch thick. Based on some quick calcs, it looks like you'd only need about a 12 inch arm with reasonable weights to produce similar pressures as a conventional machine. Besides the specimen probably being rather disturbed, it would be interesting to see how the results of that sort of test would compare with a conventional machince of standard specimen size.

 

[inaz]

Thanks Oldest, I like the ball bearing idea.

After drawing the force diagram, I see that all I need to do is sum up the moments around the pin connector to determine the proper lengths for a 10:1 ratio.

One more question, did your dial gauge rest on the top of the sample (the metal piece the ball bearing would contact), or on top of the arm?