Geotechnical : Ground Engineering of Skylines
“……in earthwork engineering the designer has to deal with bodies of the earth with a complex structure, and the properties of the material may vary from point to point.”- K. Terzaghi(Preface to the Inaugural Edition of Géotechnique (1948))
The record of a person’s first use of soil as a construction material is lost in antiquity. In true engineering terms, the understanding of geotechnical engineering as it is known today began early in the 18th century. For years the art of geotechnical engineering was based only on past experiences through a succession of experimentation without any real scientific character. Based on those experiments, many structures were built, some of which have crumbled, while others are still standing.
What is Geotechnical engineering?
The process of understanding and working with soil and rock, underground water, site, and structural conditions, in relation to a construction project, is known as geotechnical engineering.
Responsibilities of geotechnical engineers
In their professional capacity, geotechnical engineers plan and design the structures for buildings, roads, embankments, canals, and hundreds of other construction projects. Beyond their construction role, the geotechnical engineer will also deal with geological hazards like landslides, soil erosion, and, in some extreme conditions, earthquakes. Geotechnical engineers tend to be practical people who are good at using mathematics and mechanics and who enjoy working outside, as well as in an office environment.
Geotechnical engineering is a multidisciplinary field
You’ll be expected to have a working knowledge of a number of engineering fields — including ocean engineering, structural engineering, petroleum engineering, and material science. The information and research data which you’ll be expected to deal with can be varied, complex, and demanding — in addition to their engineering duties, and geotechnical engineers are mathematicians, technicians, and scientists.
Subsurface investigation: The job of the geotechnical engineer essentially starts with a collection of soil samples from the project’s intended site, using bores and test pits. Amongst other factors, the analysis will determine the ground’s stress bearing capability and stability.
Field test: After research into soil quality and stress-bearing factors, geotechnical engineers must determine whether issues like erosion, settlement and the slope will pose a safety risk to the proposed project.
Computer Analysis
As a geotechnical engineer, you will be required to analyze the results of subsurface investigations and field tests with dedicated software. Your ability to understand data and model future conditions will be crucial to the development of the construction project. After analysis, geotechnical engineers may be required to assist in the development of earthworks and foundations suitable to the conditions of the site.
Common Types of Geotechnical Monitoring Instruments Used in Construction and Mining
Geotechnical monitoring instruments play an important role in construction, civil engineering, and mining environments. They are extensively used by engineers during construction and expansion projects and as part of ongoing monitoring activities.
Within mines (surface and underground), and on major construction and civil engineering projects, engineers need to measure many different factors, of which three important ones are:
- The deformation of structures, rock, and soil
- Stresses that impact on structures like tunnels, shafts, walls, embankments, etc. as well as related to these
- The flow, pressure, and quantity of surface and groundwater
Various types of geotechnical monitoring instruments and other sensors are used by engineers to measure and provide data about different aspects of rock, soil, or water behavior, for example:
- Extensometers (e.g. MDT SMART MPBX) — Displacement
- Contractometers (e.g. MDT SMART Contractometer) — Measure convergence and compression
- Instrumented Cable Bolts (e.g. MDT SMART Cable Bolt) — Measure displacement, strain, and load
- Ground Movement Monitors (e.g. MDT SMART GMM100) — Measure general ground movement
- Slough Meters (e.g. MDT Slough Meter) — Measure sloughing or caving of ground
- Thermistors — (e.g. ThermistorString-NTC3K) — Measure ground temperature
- Hydrological Sensors (e.g. vibrating-wire piezometers and other types) — Measure aspects relating to water, e.g. depth, pressure, moisture percentage, etc.
The raw data provided by these and other geotechnical monitoring instruments and sensor types are collated, analyzed, and interpreted by engineers to give them an overall understanding of the stresses and mechanics affecting the mine. This allows them to make decisions regarding how best to manage and control the mine in a way that ensures the highest safety and productivity levels.
What does a Geotechnical Engineer do?
All construction takes place in or on the ground, so it is easy to see how geotechnical engineering plays a crucial role in all civil engineering projects. Before any construction work takes place, it is vitally important to do a site investigation. Failure to carry this out often has had negative and expensive consequences on construction projects.
Geotechnical Engineers — Foundation of structures
Geotechnical engineers figure out the impact that geological formations may have on construction projects and use advanced knowledge of scientific and mathematical processes to examine the formation of the earth beneath and around residential, commercial, or industrial buildings and structures.
Future of Geotechnical Engineering
The world population is expected to touch nine billion by 2050. Most of these increases in population will occur in underdeveloped/developing countries, where the current state of infrastructure is already critical.
Take the example of India, whereas per government estimate infrastructure requires a $282–370 billion overall to maintain the country’s gross domestic product growth at 8.5 per cent. Naturally, all of this would require the construction to be on safe ground and also be economical and earthquake resistant. That is where the role of geotechnical engineers comes in. An adequate number of qualified geotechnical engineers will be required to tackle the problems of taller and heavier structures to be found on soft soils.
Looking at the supply side, we find presently in India facilities for degree-level technical education are available at 1346 approved engineering colleges in the country with a total intake capacity of about 4.4 lakh students per year. Of these, only 340 engineering colleges offer degree-level courses in Civil/Structural Engineering with a total intake of approximately 18700 students per year. Further, Geotechnical engineering, a sub-discipline of civil engineering, is rarely being opted for specialization. ASCE statistics indicate that only 5.9% of the ASCE members have geotechnical engineering as their primary interest area. Considering the present scenario, the policymakers will have to find out the ways and means not only for enhancement of enrollment in geotechnical engineering specialization but also to incorporate the role of IT tools in geotechnical engineering practice and how they may develop their judgments skills.
The other aspect, which needs to be incorporated in the curriculum is risk assessment such as injury and financial losses involved in geotechnical engineering practice, which at present is rarely discussed. Another grey area is the non-inclusion of well-documented case studies of engineering failures in textbooks and other study materials related to geotechnical engineering. Treatment of such failures, such as Leaning Tower of Pisa, the Vaiont, Malpasset, and Teton dam failure, into standard geotechnical engineering undergraduate courses, will definitely help capture the student’s interest. It can motivate them to pursue advanced geotechnical engineering degrees.
Geotechnical engineers guard and maintain the earth’s physical environment during the development of major public and private projects. Combining their expertise in civil engineering construction and design enables them to safely investigate and analyze sites and determine their present and future stability. Projects like these typically involve significant changes to the physical environment and can include tunneling and construction of significant structures like buildings, bridges, dams, airport runways, and towers.
Written by - Devesh Pratap Singh, Abhishek Kumar Rawat and Varun.
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