Geotechnical history: Why it needs a deeper foundation

By Michael Bennett, P.E., M.ASCE (Gannett Fleming, Inc., Audubon, PA)

 

The past and present of geotechnical engineering

Next year, the geotechnical profession will mark the centennial of the first book to systematically examine its fundamentals.  In 1925, Karl Terzaghi first gained wide renown with the release of his work Erdbaumechanik auf Bodenphysikalischer Grundlage, approximately translated as Earthwork Mechanics Based on Soil Physics.  The book remains singularly impressive among Terzaghi’s many career achievements for how much its cutting-edge technical content shifted the conversation about the engineering behavior of soils and foundations.  By 1925, civil engineers had quantified some basic geotechnical principles and had seen the consequences of many others but hadn’t yet developed a coherent framework for describing these phenomena.  Thus, the field languished in a morass of stovepiped knowledge, unreliable rules of thumb, and rivalries between practitioners who tackled questions of soil engineering behavior using either theoretical or practical approaches.  Terzaghi broke this stalemate with his methodical investigation and quantification of novel concepts such as effective stress and consolidation.  These concepts, presented collectively in Erdbaumechanik, gave civil engineers a new, more organized approach to explore and solve problems of soil mechanics and foundations.

 

 

 

One hundred years later, geotechnical engineering enters its second century in a far better position.  Most of our field’s fundamental problems have been articulated, debated, and (to different extents) solved, and the state of practice is robust.  Intriguing interdisciplinary opportunities beckon to modern geotechnical researchers and practitioners and offer creative ideas for addressing the profession’s modern challenges.  The library of published geotechnical scholarship and literature is both remarkable and ever-growing.  The same methodical thinking that drove the geotechnical breakthroughs of the field’s first 100 years remains at the heart of these ongoing advances.  Simultaneously, our discipline also takes a keen interest in its heritage, which one can call geo-history.  Geo-professionals have written and continue to write many literature reviews and case histories, along with articles about aspects of geo-history.

To date, though, the methodical approach that has been central to technical advances in geotechnical engineering hasn’t been used consistently in studies of geo-history.  The topic has been explored to some extent, but its telling remains scattered and haphazard.  Thus, most modern geotechnical practitioners, teachers, and students know their professional heritage mainly through the names of a few pioneers (especially Terzaghi) and perhaps some anecdotes about them.  The ironic result is that the state of geo-history today has parallels to that of geotechnical engineering 100 years ago.  Many key facts about geo-history now, as with geotech then, are well-established, but these haven’t yet been organized so they can be fully utilized.

The benefits of revising geo-history

The sea change Terzaghi kickstarted on the technical side of geotech in the 1920s ultimately enabled civil engineers to fully appreciate what they understood about soil mechanics and foundations.  This, in turn, allowed them to start filling the gaps in their knowledge of the subject.  Likewise, starting a paradigm shift in the 2020s on how geo-history is examined will probably yield similar advantages over the current state of practice.  Geo-professionals who improve their and their peers’ understanding of how geotechnical engineering has reached where it now stands and why their forebears explored and developed the field in the directions they chose, rather than via other ones, will probably bring about many positive changes in the discipline.  Two seem particularly likely.

First, revisiting how our field has developed will help us geo-professionals improve its best practices and standard of care.  More accurately understanding geo-history will involve reexamining geotechnical ideas that have fallen by the wayside.  Some were undoubtedly disregarded because they were simply wrong, but others with more merit were just as surely overlooked because they weren’t widely circulated or predated the technology needed to take them further.  These long-forgotten ideas may well inspire new geotechnical advances and opportunities, including some tied to seemingly intractable modern conundrums.  Moreover, gaining a better understanding of geo-history will also remind geo-professionals that the field’s basic tenets are human creations which are thus prone to error.  This frame of reference will, in turn, help them critically reevaluate and (if needed) correct mistakes within existing theories and techniques.  One such scenario played out in the 1980s when Professor Emeritus Richard Handy of Iowa State University found and fixed an error in Terzaghi’s theory of soil arching while investigating a fatal retaining wall failure.  Overall, the revisions to geotechnical best practices likely to come from an improved understanding of geo-history will help geo-professionals better protect and serve the public, save time and money during design and construction, and more effectively meet their communities’ needs and improve their quality of life (Bennett et al. 2018).

 

 

Second, studying geo-history in more depth will make us more adept at learning from and appreciating the experiences of our predecessors.  Geo-history can function as a dependable catalog for the library that is the collective experiences of geo-professionals.  Constructing and using this catalog will allow us to better grasp both technical big-picture trends in our field, as described, and – perhaps even more crucially – non-technical ones.  For example, biographical sketches of geotechnical pioneers reflect that they were almost all European or American men.  This striking reality vividly underscores the importance to modern geotechnical engineering of broadening the range of perspectives within our profession by cultivating a diverse workforce.  Similarly, many geo-pioneers had divergent personalities, which at times impeded technical progress in the discipline.  Examining the various interpersonal styles of the early geotechs and how they meshed or conflicted has the potential to be tremendously valuable to modern professionals and academics in the field, all of whom navigate similar challenges in their own careers at some point.

New lines of inquiry in technical disciplines are deservedly subject to discussion and skepticism, especially a non-traditional one like geo-history.  Such scrutiny can only improve the study of geo-history as it develops, much as it did with geotechnical engineering.  The new discipline was not universally popular upon its debut, and Terzaghi spent nearly 15 years after Erdbaumechanik’s publication defending the principles of soil mechanics against detractors who maintained, as one wrote in 1937, that it “has caused no visible progress in: 1) The art of foundation design; and 2) the methods for computing slope stability.”  Only during World War II did geotechnical engineering finally gain universal acceptance as developments such as the Modified Proctor test and USCS proved its mettle on the battlefield.  Similarly, a methodical study of geo-history will likely lead to numerous practical benefits from its inception, as described, and will almost assuredly lead to more as research continues (Peck 1993).

A new approach to geo-history

Consulting primary sources is, perhaps, the soundest method for geo-professionals to start meticulously investigating their discipline’s evolution.  They can begin exploring geo-history by reading an article or chapter of their choice from historical geotechnical literature and writing a review on it.  Then, as they continue their studies, they can compare different historical sources.  Such a building-block approach is more likely to uncover larger geo-historical trends than reading a few geo-historical works which are already prominent.  For instance, Victorian sources on lateral earth pressures reflect how intensely civil engineers feuded before the dawn of geotechnical practice based on whether they designed designing retaining walls and supports of excavations using mainly theory or a combination of field experience and rules of thumb.  Only in the 1920s did Terzaghi solve the issue by combining the two clashing approaches into semi-empirical procedures for assessing soils’ engineering properties.  The rediscovery of this bygone antagonism and other similar geo-historical trends will steadily make geo-history more valuable for guiding the profession’s future.

Using a step-by-step approach to explore geo-history has abundant precedent in the analogous technique Terzaghi utilized a century ago to do his pioneering technical research on consolidation and effective stress.  Terzaghi’s protégé, Ralph Peck, noted decades later of his mentor’s early work that “the theory was developed after the experiments.  Only when Terzaghi felt that he understood the phenomenon on the basis of intensive study of the data from tests on real foundation materials did he turn his attention to a mathematical theory embodying the results.”  Terzaghi and Peck discussed this methodology at length during their collaborations, and Peck later refined it into the modern observational method.  Likewise, using an incremental, source-driven methodology to research and revamp geo-history it will make it more accurate and, therefore, more useful to geo-professionals as well (Peck 1993).

 

Geo-history: Current work and its future

Methodically studying geo-history using a source-driven approach has the potential to help strengthen the geotechnical discipline by ushering in new solutions, techniques, and ways of thinking.  It will help geo-professionals refine and, as needed, correct the field’s fundamental principles, thereby improving best practices and public safety.  Furthermore, it will assist them in drawing upon their predecessors’ experiences to navigate the daily challenges both they and the field as a whole face.  The findings of even a preliminary geo-history review demonstrate the subject’s worth to the profession. (The writer has begun performing such work through his geo-history blog entries posted on the Geo-Institute website.) More and equally valuable findings are likely as geo-history puts down deeper roots.  Given time and attention, it seems likely to become a self-sustaining niche topic within geotechnical engineering.

Studying geo-history will take time to pay dividends to the geotechnical engineering profession, and the process of understanding the field’s evolution will probably never be complete.  However, its probable long-term benefits remain immense, and the subject beckons to be studied.  Perhaps no one expressed the value of such studies of history more succinctly or eloquently than legendary British Prime Minister and Nobel Prize-winning historian Sir Winston Churchill.  “The longer you look back,” Sir Winston once noted, “the farther you can look forward” (Manchester 1983).

 

 

Acknowledgments

Sebastian Lobo-Guerrero, Ph.D., P.E., BC.GE., M.ASCE (A.G.E.S., Inc.: Canonsburg, PA), the author’s onetime colleague, reviewed a draft of the entry.  Thomas Kennedy (Geopier: Davidson, NC), the author’s Virginia Tech classmate, co-wrote several previous iterations of this entry, the most recent of which appeared as a 2023 Deep Foundations magazine article.

 

References

Bennett, M.D., T.J. Kennedy, T.J. Quick, and W.P. Shaffer. 2018. “Lessons learned from GeoLegends: Richard L. Handy, PhD, F.GSA, F.AAAS.” GeoStrata, 22 (6), 22-31. https://ascelibrary.org/doi/10.1061/geosek.0000235 

Manchester, W.R. 1983. The Last Lion: Winston Spencer Churchill, Vol. 1 – Visions of Glory (1874-1932). Boston, MA, USA: Little, Brown and Company.

National Portrait Gallery. 2024. “Winston Churchill (Yousuf Karsh, 1941).” National Portrait Gallery. Accessed Apr. 28, 2024. https://www.npg.org.uk/collections/search/portrait/mw08607/Winston-Churchill 

Peck, R.B. 1993. “The coming of age of soil mechanics: 1920-1970.” 1st Spencer J. Buchanan Lecture, Oct. 22. Texas A&M Univ., College Station, TX, USA.

Peck-Young, N. 2024. “Photo #28.” Professor Ralph Peck’s Legacy Website. Accessed Apr. 28, 2024. https://peck.geoengineer.org/resources/photos/2/singlePhoto/35 

Withiam, J.L. 2024. “Photo of the 1st International Conference on Soil Mechanics and Foundation Engineering that was held in 1936 in Harvard.” Geoengineer. Accessed Apr. 28, 2024. https://www.geoengineer.org/education/history/1936-issmfe-group-photo-in-harvard