Geotechnical engineering, then and now – PART I

Geotechnical engineering — A story to know

Throughout history, many catastrophic events could have been avoided if geotechnical engineering had been a reality at the time. Humans built structures such as buildings, bridges and dams, and dug tunnels and holes without the scientific knowledge to back their plans and thus ensure the stability and safety of their structures.

Let’s put first things first. You’ll ask, “What exactly is geotechnical engineering?”

Simply put, geotechnical engineering is the story of humans’ relationship with the Earth.

It’s also the science behind the mechanics of soils and rocks, and the art of applying that science to the development of civilization. After all, nearly everything around you is supported by soil or rock. Anything that isn’t either flies, floats or falls. It’s a simple fact.

In earlier times, geotechnical engineering was a process of trial and error, empirical experimentation and observational experience. Problems with structures like the Leaning Tower of Pisa led engineers to start using a more scientifically based approach to geotechnical engineering.


The 1700s: the beginning

Between the early 1700s and the 1900s, scientists like Darcy, Rankine, Coulomb, Boussinesq, Mohr and Atterberg published their theories, creating fundamental works on soil mechanics and water flow through soil. Furthermore, in the 1900s, several prominent organizations and societies were formed to advance the field of civil engineering.

There is particular recognition given to Karl von Terzaghi, an Austrian mechanical engineer who is considered to be the father of modern geotechnics, having written a classic book on soil mechanics that was published in 1925.

The International Society for Soil Mechanics and Geotechnical Engineering is born

It is in 1936 that Terzaghi and colleagues from 20 other countries founded what is now known as the International Society for Soil Mechanics and Geotechnical Engineering, or ISSMGE. Not surprisingly, he became the Society’s first president. Nowadays, this international society includes more than 90 member countries and 19,000 members, most of whom are geotechnical engineers, academics and contractors.

Hidden truths

What most geotechnical engineers do is, well, buried. However, it is an essential discipline with a vast scope, since all constructions must sit on or in the ground. Soil is a highly complex material that varies in grain size, strength, cementation and behaviour. This makes the task of analyzing it all the more challenging for geotechnical engineers. In fact, it arguably makes the discipline one of the most complex in the field of civil engineering.

Key operations: investigating, evaluating, designing and building

Using the fundamental principles of rock and soil mechanics, geotechnical engineers investigate what is known as sub-surface conditions. This allows them to evaluate, plan and design a number of activities: assessing the stability of man-made soil deposits and natural slopes; planning earth works with cuts and fills; determining whether foundations should be deep or shallow; designing retaining walls, dams and tunnels along with many other works that interact directly with water and subsoil.

To deal with the various challenges this profession faces, the ISSMGE has established 30 different technical committees over the past 50 years. Each of these committees represents a specific aspect of geotechnical engineering.

Each site is unique

Every site has its own set of components

The soil at one site is invariably different from any other site, requiring thorough analysis. This makes all geotechnical projects different. For that reason, the first step of any geotechnical project is investigation. Phase one involves drilling into the soil and rock layers while performing field testing and collecting samples to be later analyzed in a lab. After determining the properties of the rocks and the soil present, geotechnical engineers are able to design the project, which includes determining the environmental impact. Investigations may also involve assessing the risks to humans and property and minimizing the risks associated with natural disasters such as landslides, earthquakes, sinkholes, rock falls and even soil liquefaction.

We will continue with this topic and share how it has evolved into the discipline we know today in our next article. Stay tuned for more!