Introduction to Soil and Soil Mechanics
To an Engineer, Soil is the un-aggregated or un-cemented collection of mineral and/or organic particles or fragments covering the large portion of the earth's crust.
Soil Mechanics is one of the subject of Civil Engineering involving the study of soil, its behavior and application as an engineering material. According to Terzaghi : "Soil Mechanics is the application of laws of mechanics and hydraulics to engineering problems dealing with sediments and other unconsolidated accumulations of solid particles produced by the mechanical and chemical deformation and transformation of rocks regardless of whether or not they contain an admixture of an organic constituent."
Geotechnical Challenges Arising in Civil Engineering and Infrastructure Development
The major geotechnical problems that are generally occurring in civil engineering are as follows:
Importance of Soil Mechanics
Soil engineering is an applied science which deals with the applications of principles of soil mechanics in practical problems. It deals with all engineering challenges related to soils. It comprises of site investigations, design and construction of foundations, earth retaining structures, and earth structures. Soil engineering has the large application in the construction of various civil engineering works. Some of the important applications are as follows:
Historical Development of Soil Mechanics
Soil engineering was used based on the experience of past engineering work
Most designs were often based on “rule of the thumb”
During Roman times, heavy structures such as bridge, aqueducts, harbors and buildings, roads were built, where we can find the application of soil
Most theories in soil mechanics were developed after mid-1700’s
Other important names are Taylor, Skempton, Bjerrum, Lame, Rowe etc.
Soil Formation and Soil Type
The geologic cycle explains the process of rock and soil formation.
Soils are formed either by physical disintegration or chemical decomposition of rocks. Physical disintegration or mechanical weathering of rocks occurs due to following physical processes:
Chemical decomposition changes the chemical composition of rock i.e mineral properties changes. The following chemical processes generally occur in nature.
Residual and Transported Soils
Those soils which are formed and are at the place of formation or origin are residual soils while those which are moved and deposited in other places by transporting agents like water, wind, glaciers, gravity, etc. are transported soils.
Transported soils can be classified as follows: