Topic 3 classification of coarse soils Flashcards
What does a description of a soil tell us?
A statement describing the physical nature and state of the soil.
How are soils described?
Soils are described by visual examination, simple tests, observation of site conditions, geological history, etc.
What is soil classification?
The separation of soil into classes or groups of similar characteristics and potentially similar behaviour.
What does the angularity of a soil particle depend on?
The amount of wear during transportation.
If the particles are rounded, how was it transported?
Transported by water over long distances.
If the particles are angular, how was it transported?
Not transported by water (at least not far); transported by ice (glaciers) or wind or gravity alone.
If the particles are sub-angular and sub-rounded, how was it transported?
These soils may have been transported by water over short distances.
Define the term uniformly graded.
One single grain size.
Define the term even-graded.
Small range of grain sizes.
Define the term medium-graded.
Medium range of grain sizes.
Define the term multi-graded.
Wide range of grain sizes.
How is the effective size determined?
It is found by the largest size of the smallest 10%. (D10)
How is the uniformity coefficient determined?
Cu = d60 / d10.
How is the coefficient of curvature determined?
πΆπ=(π30^2)/(π60Γπ10 ).
How is water content within a soil calculated?
The ratio of the amount of water to the amount of dry soil.
In a graphical sense, what indicates the distribution of the soil particles?
The shape of the grading curve.
Define the shape of the curve of a well graded soil.
Shallow gradient and extends evenly over the range of particles within the soil.
What are the two types of poorly graded soil?
Uniformly graded and gap graded.
Define the shape of the curve of a uniformly graded soil.
Majority of the curve is steep, therefore most of the particles will be the same size.
Define the shape of the curve of a gap graded soil.
Curve is steep in bigger and smaller particle sizes and shallow in intermediate sizes.
