Geotechnical engineering is a concerned with any material that is at or near the surface of the Earth. These are naturally occurring material and termed as soil and rocks. Engineer defines soil as any loose material which is agglomerate and organic thus sediment formed above bed rock. Soil is a material that can easily be broken into its constituent. Rock on the other hand is a firm material where cohesive forces and constituents are held together. There is a fine line between rock and soil as engineer defines so it can be a very soft rock or even a hard soil. Well other definitions about rock and soil is different as a geologist defines anything occurring in the Earth as rock despite of the minerals bound together and soil to him is disintegrated and decomposed rocks found at the upper most part of the Earth. Same way pedology (study of soil) and to agronomist soil is the upper most layer that has to do with growing plants.
So therefore a geotechnical engineer works with collaborative knowledge of geology and pedology. They studies soil and rocks mechanics, which is related to both its physical properties and mechanical properties. So what does geotechnical engineer do?.
Geotechnical engineer have knowledge about soil and rock mechanics, dynamic, kinematics. This knowledge is applied to construction and designing any building, tower, houses etc. The knowledge how soil reacts when is saturated or loose is very important or the building foundation will not be strong. Similarly rock mechanics is needed for the foundation. A geologist with this knowledge work with engineer for the building foundation, pavement, roads, railways etc. Dams needs serious study about underneath rocks or soil study as water will saturate the below soil and rocks. This study is done by geologist so that dam can be constructed without risk of failing. There are soils which swells on saturation should be excavated for the dams. Geologist has a key role with the knowledge of engineering where the Earth study is important for any construction without this it can fail by not firm foundation.
Soil and rock physical properties and mechanical properties are the basic knowledge for the engineering perspective.
