Soil Origins and Classification

Question 1

Soil vs Rock

Answer 1

• both are natural aggregate of mineral grains
• soil aggregates can be separated by mechanical means: agitation in water
• Rock aggregate minerals connected by strong forces

Question 2

Soils are products of….

Answer 2

….rock weathering

Question 3

4 types of soil classification

Answer 3

1) Gravel - small rocks consisting a mix of minerals
2) Sand - small grains of a single mineral
3) Silt - smaller grains not visible to naked eye
4) Clay- tiny plate-like (usually) minerals

Question 4

How is soil different to other engineering materials and what does this lead to

Answer 4

• three phases (solid soil grains, liquid water and gaseous air(
• leads to complex behaviour

Question 5

Why is soil a frictional material

Answer 5

• engineering properties depend on the confining stress e.g. strength
• generally no tensile strength

Question 6

When under stress soil experiences ________ behaviour

Answer 6

non-linear plastic

Question 7

Why is there high uncertainty in behaviour of soil

Answer 7

• natural material i.e. every soil is different

Question 8

Four geotechnical challenges of soil

Answer 8

• settlement (consolidation settlement can occur over decades or longer)
• strength (bearing capacity and slope stability)
• seepage
• liquefaction