30 GeoLegend: Sandra Houston

18 Adaptive Management of Urban Excavations

JANUARY // FEBRUARY 2019

Proudly published by the Geo-Institute of ASCE

computationalgeotechnics

46 VR & AR in Geotechnical Engineering

38 Automated Model and Parameter Selection

10 GEOSTRATA JANUARY/FEBRUARY 2019

From the Editorial Board

This issue of GEOSTRATA on

Computational Geotechnics

has reminded me of my

graduate school days. In

the early to mid-1970s,

numerical methods in

geotechnical engineering

were moving from their

infancy a decade earlier, to

becoming an increasingly

important tool for research and occasional

engineering practice. The barriers to greater use

of computational tools in those years included

a lack of versatile and robust numerical models,

graphics interfaces to check input data and

present output graphically, and user training.

Fast forwarding nearly 50 years (where did the time go?), we’ve solved each of these barriers, but others have surfaced. For example, as Rich Finno says in his commentary: while today’s numerical models “are quite powerful,” they can be “at times, frighteningly easy to use.” And while many geotechnical engineers have at least some experience using numerical tools, maybe a greater concern today is the number of geotechnical analysts we graduate who lack basic training in the earth sciences to understand the importance of local geology on the problems they’re trying to solve.

But I digress. As articles in this issue make clear, we’re using advanced computational tools in ways not envisioned even just a decade ago. I know I’ve learned something, and I hope you do, too.

What’s Inside?This issue contains two commentaries. We begin with “Adaptive Management of Urban Excavations,” by Rich Finno, which outlines how sensor and information technology can be combined with numerical analyses to automate the cycle of field observations to update performance predictions. For excavations, he describes how monitored performance data can be incorporated into an optimization routine to update

numerical design computations, and form a rational basis for changing means and methods to meet performance criteria.

Geotechnical engineers must deal with the ground conditions at project sites, so understanding a site’s geology is a must. But are civil engineers trained to ask the right questions? Richard Jackson says no in our second com-mentary, “Civil Engineering Educators Must Teach Applied Geology to Their Students.” We learn this has been a lament for decades that isn’t getting better with time as more varied, but non-geologic, content is added to civil engineering curriculums, and credit hours for graduation are reduced.

A key success factor in numerical analysis of geotechnical problems is the selection of an appropriate constitutive model and input parameters, but too often from limited data. While success can be improved with training, experience, and information exchange, these paths for improvement can be a challenge for engineers who only occasionally use numerical methods to solve geotechnical problems. But Ronald Brinkgreve offers an alternative approach in “Automated Model and Parameter Selection,” whereby expert input helps augment geotechnical analyses using computational tools.

Possibly the greatest subsurface construction challenge has been our relative inability to visualize complex condi-tions underground. In “The Present and Future of Virtual and Augmented Reality in Geotechnical Engineering” by Dimitrios Konstantakos, we learn how these technologies are transforming foundation and geotechnical engineering to improve our ability to visualize complex subsurface condi-tions in 3D, and help explain them to clients. And as Martha Stewart often says, “It’s a good thing.”

As LRFD has become more commonplace, engineers now recognize that the true margin of safety in probabilistic terms is unknown. As an alternative, reliability-based design offers more flexibility in adjusting design parameters to meet or exceed a target level of safety, but many are unfamiliar with the mathe-matics to apply the approach, or view it as tedious if they do. In his article “Reliability-Based Design (RBD) for Everyone,” Richard Bathurst explains that Monte Carlo simulation is not needed for some of the common design problems he introduces.

Time and again, performance monitoring has helped improve foundation design practice. In “Micropiles Support the ‘Missing Link’ — Understanding Load Transfer in Challenging Subgrades,” Audai (Ed) Theinat and Ronaldo Luna use numerical modeling to demonstrate that the design assumption that load is not transferred in the cased zone can be overly conservative.

JAMES L. WITHIAM

djacksonHighlight

22 GEOSTRATA JANUARY/FEBRUARY 2019

Civil Engineering Educators Must Teach Applied Geology to Their Students

As I See It

By Richard E. Jackson, PhD, P.Eng.

23www.geoinstitute.org

Nearly 40 years ago,

ASCE published an

article making the same

argument as the title I use

above, if not stated quite

as forcibly. The author,

Richard Proctor, was the

first engineering geolo-

gist at the Metropolitan

Water Board of Southern

California, and eventually

became its chief geolo-

gist. Proctor noted that a

“large proportion of civil

engineering graduates

have had none, or only

minimal, exposure to

applied geology in our

universities.” In the U.S.,

this appears to be as true

today, and maybe truer,

than it was in 1981.

How is that possible when we are building ever-longer tunnels in rock masses with complex stress regimes, deep geological repositories for nuclear waste, and pipelines and highways for routes crossing active faults and terrain with evidence of landslides and rockfalls? Furthermore, coastal infrastructure is threatened by sea-level rise and eroding shorelines, municipal water wells by groundwater contamination, subsidence caused by groundwater extraction, and bridge collapse by scour during floods.

I’m advised by a distinguished aca-demic engineering geologist that various financial pressures on universities have

pushed them to reduce the number of credit hours from around 140 to roughly 120, depending on the institution and the degree of state financial support. If ”applied geology” is taught to civil engineers, it’s likely the course is an introduction to physical geology, which is not what either Proctor or I would call “exposure to applied geology.”

Readers can reflect on the vast changes to geotechnical engineering since 1981 that have resulted in the name change of the ASCE journal from ”soil mechanics” to ”geotechnical and geoenvironmental engineering.” Similarly, ”geology” underwent extraor-dinary growth, such that most academic departments today adopt the title “earth sciences” — rather than geology — to indicate the broad expanse of relevant knowledge invested in rock mechanics, geomorphology, hydrogeology,

earthquake science, and aqueous geochemistry. Thus, I’m concerned that geotechnical and geoenvironmental engineering graduates each carry a working knowledge of these applied earth sciences with them into practice.

The standard course in physical geology should be regarded as part of the liberal arts education of an engineer, not a course that will assist a graduate engineer to protect the public and its infrastructure during his or her years of practice. Proctor was most insistent that a course in physical geology not be confused with “exposure to applied geology.” As noted Canadian civil engineer Robert Leggett explained in his 1979 Terzaghi Lecture, earth sciences should be introduced to civil engineering students “in a manner that will illustrate the relevance of geology to civil engineering.”

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Bi-Directional Static Load Testing

24 GEOSTRATA JANUARY/FEBRUARY 2019

In fact, in his 1957 Presidential Address in London to the 4th International Conference on Soil Mechanics and Foundation Engineering, Terzaghi was explicit in this need:

“I believe that a two-semester course combined with field trips fully serves its purpose, provided that the course represents the combined efforts of a geologist who appreciates the requirements of engineers and an engineer who has learned from personal experi-ence that geology is indispensable in the practice of his profession.”

Does any reader doubt the validity of Terzaghi’s observation for the 21st cen-tury? While it’s admirable that courses in communication, humanities, and social

sciences are required as electives for civil engineering students, knowledge of the applied earth sciences is necessary because engineers are responsible for public safety. An articulate engineer with deep knowledge of the works of Thoreau and Lincoln still needs to appreciate how bridges fail through scour and how slopes fail because they are part of an active groundwater flow system.

Recognizing these are aspirational goals, what can realistically be done to safeguard the public interest so that civil engineering graduates are exposed to the applied earth sciences? The range of relative earth science topics is extraordinary in its breadth: structural geology and zones of inherent weakness in rock masses; glacial processes with an emphasis on the properties of glacial sediments; weathering of exposed

bedrock producing unstable soils; flu-vial processes with particular focus on fluvial erosion and sediment transport; identification of active faults from geo-morphic evidence; role of hydrogeology in site characterization; and the nature of pore-pressure changes affecting slope stability.

Given this list — and other items that might reasonably be added to it — I believe that the teaching of the applied earth sciences to civil engineers needs to be rethought. Moreover, the key to such teaching must consider the developing insight and maturity that an undergraduate engineer gains during his or her education.

In the preface to his 1993 text Engineering Geology: Rock in Engineering Construction, Richard Goodman, professor emeritus of civil

As I See It

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engineering at UC Berkeley, observed that “no doubt, mastering advanced engineering mathematics or thermo-dynamics is ‘harder’ for some students than understanding the principles of engineering geology. But in the practice of engineering, geology may prove to be the harder subject. The penalties for geologic mistakes can be severe…”

So, if one accepts Terzaghi’s recommendation of instruction in the applied earth sciences, I believe that it’s wise to introduce the undergraduate civil engineer to “the principles of engineering geology” after he or she has completed courses in solid, fluid, and soil mechanics. In this way, the undergraduate can appreciate that the applied earth sciences are cut from the same cloth as engineering mechanics. Furthermore, such teaching must be

accompanied by practical applications and case histories if “the penalties for geologic mistakes” are to be illustrated and avoided.

It’s noteworthy that the greatest geo-technical engineers, including Terzaghi, Deere, Skempton, Peck, and Burland, made significant contributions to “the principles of engineering geology.” As John Burland wrote of the geotechnical triangle, one of its three legs is the ”ground profile,” or the concise and accurate characterization of soil and rock at a site. The measured behavior of the ground is coupled with the ground pro-file to produce an idealized site model.

It’s time to reintegrate the applied earth sciences within civil engineering curricula, whether in the final years of an undergraduate education, or in the first year of an MSCE course. ASCE’s

2008 Body of Knowledge for Professional Practice indicates that licensing of U.S. engineers may, in the future, require an MS degree or equivalent; thus, there exists an opportunity to adopt Terzaghi’s recommendation.

j RICHARD E. JACKSON, PhD, P.ENG.,

is a fellow at Geofirma Engineering in

Ottawa, Canada, and an adjunct professor

of earth and environmental sciences at the

University of Waterloo. He received the

2008 Geoenvironmental Award from the

Canadian Geotechnical Society, and the 2013

Farvolden Award from the Canadian National

Chapter of the International Association

of Hydrogeologists. He is the author of

Earth Science for Civil and Environmental

Engineers, to be published by Cambridge

University Press in March 2019. He can be

contacted at rjackson@geofirma.com.

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2018-11-28 Geostrata JAN-FEB.indd 1 11/28/18 11:17 AM