Procedures for Sampling Soil "Article"

There are two types of samples:

A- Disturbed Samples: 

These types of samples are disturbed but representative, and may be used for the following types of laboratory soil tests :
1- Grain size analysis.
2- Determination of liquid and plastic limits.
3- Specific gravity of soil solids.
4- Determination of organic content.
5-Classification of soil.
6-But disturbed soil samples cannot be used for consolidation, hydraulic conductivity, or shear tests, because these tests must be performed on the same soil of the field without any disturbance (to be representative)
The major equipment used to obtain disturbed sample is (Split Spoon) which is a steel tube has inner diameter of 34.93 mm and outer diameter of 50.8mm.

B- Undisturbed Samples: 

These types of samples are used for the following types of laboratory soil tests:

1- Consolidation test.
2-Hydraulic Conductivity test.
3- Shear Strength tests.
These samples are more complex and expensive, and it’s suitable for clay, however in sand is very difficult to obtain undisturbed samples. The major equipment used to obtain undisturbed sample is (Thin-Walled Tube).

Degree of Disturbance
If we want to obtain a soil sample from any site, the degree of di
for a soil sample is usually expressed as

equation

AR = area ratio (ratio of disturbed area to total area of soil)
Do = outside diameter of the sampling tube.
iD= inside diameter of the sampling tube.

If (AR) ≤ 10% → the sample is (UNDISTURBED)
If (AR) > 10% → the sample is (DISTURBED)

example