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In-situ soil test without apparatus

posted Sep 9, 2018, 7:30 AM by jeffery jim

So you are all alone and you are far away from your geotechnical engineer. How do you decide the type of soil properties?

As someone who is in control of the site, you can make a few assumptions. You need to develop some 'HAND'y skills. In order to determine some parameters, you have to check the physical consistency of a soil using your hand. There are several considerations.

1. Soft Consistency (very easily deformed by squeezing)
2. Firm Consistency (hard to deform by hand squeezing)
3. Stiff Consistency, Sr >0.8 (Easy to penentrate by Nail, degree of saturation >0.8
4. Stiff Consistency, Sr <0.8 (Easy to penentrate by Nail, degree of saturation >0.8
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5. Very Stiff Consistency, Sr >0.8 (Dry, crumbles when hit by a hammer, degree of saturation
6. Very Stiff Consistency, Sr <0.8 (Dry, crumbles when hit by a hammer, degree of saturation
7. Very Soft Consistency (Squishes between fingers when squeezed)

Item 1 to 4 can determine the estimated soil's angle of internal friction, cohesion and angle of friction soil-structure wile item 5 to 7 require laboratory test.

Aside from squeezing, rolling test similar to Atterberg Test will give you fair estimation about its soil class based on its plasticity index.

In this case, it is a high plasticity clay with very low angle of internal friction. Class? CH soil class most likely.

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