INTRODUCTION OF GEOTECHNICAL ENGINEERING :
The practice of engineering that involves application of the principles of soil
mechanics is called soil engineering. Similarly, the practice of engineering that involves application of the principles of rock mechanics may be called rock engineering. Because rock mechanics for the most part grew out of soil mechanics, a close relationship exists between these engineering disciplines, which now are collectively referred to as geotechnical engineering.
Foundation engineering is the application of geotechnical engineering for the design of foundations for structures including buildings, walls, and embankments; the total load supported by a foundation obviously must not exceed the supporting capacity of the underlying soil. Less obvious, but also of critical importance, is that settlement of the completed structure must not be excessive or uneven.
Geotechnical engineering also is involved in highway engineering and in engineering for dams. A more recent application of geotechnical engineering is geoenvironmental engineering, which involves assessment, prevention, and mitigation of ground and surface water pollution from landfills, lagoons, and hazardous waste sites.
The first step in a site investigation is to identify the geological conditions, which can profoundly influence the plan and methods of the investigation. For example, borings performed on a hill whose flanks reveal a persistent rock outcrop will be far different from those performed in a river flood plain where rock may be tens or hundreds of meters deep. A preliminary assessment is made through recognition of surface features, reference to geological and agricultural soil maps, and records from prior borings in the vicinity.