Geotechnical engineering, being a branch of civil engineering deals with design, analysis and construction of foundations, retaining structures, slopes, embankments, levees, tunnels, landfills, wharves and other structured consisting of or supported by rock and soil. A geotechnical engineer is involved in evaluation of earth materials, such as groundwater, soil, rock and their interaction with retention systems of the earth, its structural foundations, etc. Geotechnical engineer is required to be aware of the basic engineering principles, such as, dynamics, statics, behavior of engineering materials and fluid mechanics. One should also possess general understanding of construction techniques and the civil engineering performance affected by earth materials.
A geotechnical engineer views soil not simply as an agronomic material, but also volcanic ash, broken rock pieces, alluvium, glacial material and any other transported and residual products. Difficulties often arise, since the line between soil and rock is not always so vivid. For instance, while a geologist classifies a certain material as a formational rock, due to its belonging to a certain geologic environment, a geotechnical engineer may consider it to be enough friable or weathered to be classified as a soil.
The task of a geotechnical engineer’s consists in exploring the subsurface conditions of the project site, determining the soil capacity to carry the load without experiencing movement or collapsing, as well as giving recommendations regarding appropriate foundation alternatives. There may be also a necessity to give recommendations about related areas, such as earthwork and groundwater. Such expansive soil exploration program often includes a number of analyses performed with soil for testing and classification purposes. The geotechnical engineer is primarily interested in two types of information derived from such testing. These are: characteristics of the encountered material, as well as calculated values and engineering properties of the soil.
The type of encountered material is of great importance, since it gives an indication of how the soil may react on load, and whether or not foundations may be supported with a certain material. Studying properties of the soil is also crucial, as these provide information regarding the soil strength and ability to carry the load.
Unlike numerous engineering disciplines, geotechnical engineering is an art, rather than a pure science. It requires both experience and judgment to arrive at a safe and satisfactory solution.