Happy Karl Terzaghi’s Birthday! Yes, today is the 141st anniversary of the birth of the man considered The Father of Modern Soil Mechanics!
It has been a couple of years since I have posted a Happy Terzaghi’s Birthday note. Life – both inside and outside work – sometimes has a way of derailing us from established routines, patterns, and our “usual things”. I told myself this year would be different, so here I am! Some of you have been on my list for a few years, some of you may be new. You are always welcome to ask me to drop you, or to forward to others!
When thinking about what to write, I looked through several things on my bookshelf and ended up reading the Preface to “Soil Mechanics in Engineering Practice”, Terzaghi and Peck (1948). I am sure I read this years ago when a friend gave me this book as a gift, but today it jumped out for me to use here. Professors Terzaghi and Peck are “setting up” how they organized the book, with the “heart of the book” being the part that deals with the art of getting results in practice. This paragraph sets it up beautifully, starting with a lament that the increase in research has started to digress the profession away from the practical towards the few areas that can be precisely measured or understood (and this was in 1948!).
“Unfortunately, the research activities in soil mechanics had one undesirable psychological effect. They diverted the attention of many investigators and teachers from the manifold limitations imposed by nature on the application of mathematics to problems in earthwork engineering. As a consequence, more and more emphasis has been placed on refinements in sampling and testing and on those very few problems that can be solved with accuracy. Yet, accurate solutions can be obtained only if the soil strata are practically homogenous and continuous in horizontal directions. Furthermore, since the investigations leading to accurate solutions involve highly specialized methods of sampling and testing, they are justified only in exceptional cases. On the overwhelming majority of jobs no more than an approximate forecast is needed, and if such a forecast cannot be made by simple means it cannot be made at all. If it is not possible to make an approximate forecast, the behavior of the soil must be observed during construction, and the design may subsequently have to be modified in accordance with the findings. These facts cannot be ignored without defying the purpose of soil mechanics. “
How true at times this is still today! Our high-tech world sometimes leads us into the trap that the answer is better the more precise we can be in our capture, measurement, analysis, and calculations. However, simple is many times still as precise as we need and we must be able to know when that is the case, and how to convey it to others. We also need to know how to back-check our complex models with a simplified hand calculation or “eye ball” judgment.
So, raise that mug of coffee, cup of tea, can of Red Bull, or favorite after-hours beverage (when it is after hours!) to the timeless words from two of the “founding fathers” of geotechnical engineering and practice. Have a great Karl Terzaghi’s Birthday!
Dan Ding, Ph.D., P.E.
