What is Geotechnical Engineering?
Although Geotechnical Engineering is a fundamental part of any project linked to the infrastructure that makes our civilization possible, few professionals have an answer to this question. In this post we will clarify what Geotechnical Engineering is, what disciplines it encompasses, and why it is so important in every civil project.
Content
Definition
The first thing to take into account is that Geotechnical Engineering is a specialization of Civil Engineering. Therefore, it is important to be clear about what Civil Engineering is. Civil Engineering is the discipline that includes the analysis, design and construction of a large number of structures and systems, many of which are built on, in, or with soil or rock (Mitchell & Soga, 2005). It could be said that, basically, it is the discipline that provides and maintains the infrastructure that makes our civilization possible (from bridges, piers and skyscrapers, for instance, to spacecraft launch facilities).
Figure 1 Examples of structures that make our civilization possible (Source: compiled from www.google.com).Fuente: recopilado de www.google.com).
From the above, it is evident the need for a specialized branch of Civil Engineering, particularly oriented to understand the properties and behavior of soils and rocks. Thus, Geotechnical Engineering arises, which is defined as the discipline that encompasses the application of Civil Engineering technology to natural materials found on or near the earth's surface (Holtz et al, 2011).
The Geotechnical Commission of the Swedish State Railways was the first institution to use, around 1922, the term Geotechnics in the current sense: the combination of geology (from Greek geo = earth; and logos = study, treatise, science) and technology (from Greek tecno = art, technique; and logos = study, treatise, science). It follows that Geotechnical Engineering results from applying technology (i.e., the practical application of knowledge generated by science - in this case Civil Engineering) to geology (i.e., the study of the earth).
Figure 2 Definition of Geotechnics.
Based on the above, it is possible to intuit that Geotechnics implies an association between theory, necessary to understand the physical and mechanical conceptual bases that govern certain phenomena associated with the behavior of soils and rocks; and the practical application of these concepts in any civil project.
What disciplines does Geotechnical Engineering encompass?
Geotechnical Engineering encompasses the study and practical application of diverse concepts and theories, which can be grouped into three main branches:
- • Soil Mechanics. It includes the application of the basic principles of mechanics to soils, including kinematics, dynamics, fluid mechanics, and mechanics of materials. Accordingly, soil (like water, steel or concrete, for example) is considered an engineering material, whose properties and behavior must be understood in order to build with, in or on it.
- • Rock Mechanics. Similar to the previous case, it includes the application of the basic principles of mechanics to rocks, considering them as an engineering material.
- • Foundation Engineering. This branch applies Geological Engineering, Soil Mechanics, Rock Mechanics and Structural Engineering to the design and construction of foundations for civil projects. The main goal of this discipline is that the Geotechnical Engineer is able to predict the behavior and response of the soil or rock foundation to the stresses coming from the superstructure.
The following chart outlines the branches of Geotechnical Engineering, highlighting the general scope of each.
Figure 3 Disciplines grouped in Geotechnical Engineering.
Often, in practical engineering, the three branches mentioned above are analyzed as different parts of the same problem: it is necessary, first, to determine and understand the properties of soil and/or rock materials, and then to predict and evaluate their behavior under external stresses associated with civil projects.
Importance of Geotechnical Engineering in civil projects
In Section 1 of this post, it was mentioned that Civil Engineering is basically the discipline that provides and maintains the infrastructure that makes our civilization possible. And in this context, it is worth asking why is Geotechnical Engineering important.
If we think about it, the reason is simple: it is not possible to design or build any civil structure, terrestrial or extraterrestrial, without considering the foundation soils and/or rocks. The performance, economy and safety of any civil structure are affected, and even controlled, by its foundations (Holtz et al, 2011). Let us look at some examples.
Soil and rocks are often used as construction materials because they are the cheapest possible building material. However, their engineering properties of strength and compressibility are often poor, so measures must be taken to densify them, increase their strength, or even reinforce them so that they can perform satisfactorily. Road and railroad embankments, airfields, earth and rock dams, dams and aqueducts are examples of earth structures for which the Geotechnical Engineer is responsible for their design and construction.
On the other hand, since much of the earth's surface is covered by soil (or water), rocks are important for subway structures, such as tunnels, oil storage structures, and mines, to name a few. However, some rock-related problems also occur at the surface, such as rock-supported building foundations and dams, deep excavations in bedrock, or stabilization of rock slopes.
In the last 20 to 30 years, geotechnical engineers have been increasingly involved in solving environmental problems, particularly those involving soils and rocks. Among the more complex problems are those associated with contaminated water, proper disposal of solid waste, design and construction of nuclear waste repositories, and mitigation of hazards associated with subway fluid deposits.
It is evident the importance of Geotechnical Engineering in any civil work, so that it is safe and functional during its useful life.
To close this article, it is important to highlight that Geotechnical Engineering combines basic mathematics and physics, geology and pedology, with such diverse branches of engineering as hydraulics, structures, transportation, construction, environment and mining, which makes it an exciting and demanding field for any professional in Civil and Geological Engineering.
References
- Holtz, R.; Kovacs, W. & Sheahan, T. (2011) “An Introduction to Geotechnical Engineering”. Second Edition. Prentice Hall. New Jersey, USA.
- Mitchell, J.K. & Soga, K. (2005) “Fundamentals of Soil Behavior”. Third Edition. John Wiley & Sons, Inc. New Jersey, USA.
