Fundamentals of Soil Mechanics for Sedimentary and Residual Soils (Wesley/Fundamentals Soil Mechanics) || Soil Formation, Composition, and Basic Concepts

✍ Scribed by Wesley, Laurence D.

• Publisher: John Wiley & Sons, Inc.
• Year: 2009
• Tongue: English
• Weight: 411 KB
• Edition: 1
• Category: Article
• ISBN: 0470376260
• DOI: 10.1002/9780470549056.ch1

✦ Synopsis

The word soil is used in soil mechanics to mean any naturally formed mineral material that is not rock. It thus covers all loose material ranging in particle size from clay through silt and sand to gravel and boulders. The main focus of soil mechanics is the material at the fine end of the range, particularly clay and silt and to a lesser extent sand.

Soils are formed by the physical and chemical weathering of rock. Physical weathering may be one of two types. First, there is disintegrationcaused primarily by wetting and drying or by freezing and thawing in cracks in the rock. Second, there is erosion-caused by the action of glaciers, water, or even wind. These processes produce a range of particles of varying sizes which are still composed of the same material as the parent rock. Sand and silt particles produced by physical weathering generally consist of single rock minerals, rather than combinations of these, as is the case in their parent rock or in gravel-sized material. It is important to recognize that no matter how fine the particle size of the material produced by physical weathering may be, it can never have the properties of clay because the chemical conversion needed to form true clay particles is not present.

Chemical weathering processes are much more complex and involve chemical changes to the mineral content of the parent rock caused by the action of percolating water, oxygen, and carbon dioxide. The minerals of which rock is composed are converted into a very different group of 1