Soil Properties
Soil is a three phase system which consists of solid, liquid and gaseous matter.
Volume Relationships
| Void Ratio | |
| Porosity | |
| Degree of Saturation | |
| Air Content | |
![\[ e = \frac{n}{1-n} \]](https://civilengghub.com/wp-content/ql-cache/quicklatex.com-c076b4e746fbd75c9f4f184503de8db8_l3.png "Rendered by QuickLaTeX.com")
![\[n= \frac{V_v}{V} \]](https://civilengghub.com/wp-content/ql-cache/quicklatex.com-a734de14fed9a0c31ad2e869e4479972_l3.png "Rendered by QuickLaTeX.com")
![\[n = \frac{e}{1+e} \]](https://civilengghub.com/wp-content/ql-cache/quicklatex.com-cc71d947a68de26c3a6c34f04f95505f_l3.png "Rendered by QuickLaTeX.com")
![\[ S = \frac{V_w}{V_v} \]](https://civilengghub.com/wp-content/ql-cache/quicklatex.com-bcd2707180df4db8bad3f034bab061e7_l3.png "Rendered by QuickLaTeX.com")
![\[a_c = \frac{V_a}{V_v} \]](https://civilengghub.com/wp-content/ql-cache/quicklatex.com-70adc632861b09bc2ba145d27a04c16f_l3.png "Rendered by QuickLaTeX.com")
![\[a_c= n(1-s) \]](https://civilengghub.com/wp-content/ql-cache/quicklatex.com-f6d8a31cafd918512305ccf9c85fc51e_l3.png "Rendered by QuickLaTeX.com")
Weight Relationships
| Moisture or Water Content | |
| Dry Unit Weight |
![\[ \omega = \frac{W_w}{W_s} \\</td></tr><tr><td><strong>Unit Weight or Moist Unit Weight</strong></td><td>\[ \gamma = \frac{W}{V} \]](https://civilengghub.com/wp-content/ql-cache/quicklatex.com-7b076a1e354aae7909bad880a0db12fc_l3.png "Rendered by QuickLaTeX.com")
Water Content
it is defined as the weight of water to weight of solid present in the given
note that:
we can derive:
Void Ratio
is the ratio of the volume of voids (air and water) to the volume of solid particles in soil.
![\[ e= \frac{V_v}{V_s} \]](https://civilengghub.com/wp-content/ql-cache/quicklatex.com-ae5050f4cb3e39e0fb531fa9ed231fbe_l3.png "Rendered by QuickLaTeX.com")
Porosity
refers to the ratio of volume of voids to the volume of soil in the soil mass.
Other formulas derived from it, the relationship between the void ratio e, and the porosity n is given by:
Degree of Saturation
is the fraction of voids filled with water.
Unit Weight
Dry Unit Weight
Saturated Unit Weight
Specific Gravity
Effective Unit Weight
Example 1
Given
Specific Gravity of Soil Solids, 
= 2.81
Void ratio, e=0.61
Degree of Saturation, S = 42%
Unit Weight of Water = 
Find the following unit weight of soil, Dry unit weight of soil, unit weight of the soil when fully saturated.
Unit Weight of Soil
Dry Unit Weight of Soil
Saturated
