What Do You Mean Moisture is 110%! Twenty Roadblocks to Communicating Engineering Geology
J. Barry Maynard, Mark T. Bowers, Paul E. Potter Introduction
Like most disciplines, in the geologi- cal sciences there is an unfortunate ten- dency to write papers and reports as though the information will only be read by those initiated into the culture and practices of their own group. This is the source of the consternation expressed in our title, when we encounter an unfa- miliar culture, in this case geotechnical engineering. These cultural boundaries give rise to countless examples of confu- sion in communicating, sometimes with tragic consequences.
A seminal work that analyzes issues of poor communication is the book by Robert Graves and Alan Hodge “The Reader Over Your Shoulder” rst pub- lished in 1943 in the UK and in a 1971 US edition with many reprints. They urge writers to constantly keep in mind the members of their audience, imagin- ing their complaining about confusing sentences or undened argon. In the same spirit we urge geologists to write with a wider audience in mind rather than other geologists. To facilitate this broader approach to writing, it is es- sential for geologists to realize and ap- preciate some of the subtle but impor- tant distinctions in the way geologists and other scientists and engineers use seemingly identical terms.
It may seem an annoyance to have to carefully explain what would seem to be understood by every geologist, but this body of assumed knowledge does not ex- tend outside of geology and worse, many terms that look familiar are in fact used in surprisingly different, even opposite ways. This potential for a breakdown in communication is great. Mitchell, in his 2004 Seed Lecture (Mitchell, 2009), identied communication, in particular the failure to adequately dene terms and conditions, as the number one rea- son for geotechnical failures.
The Engineer Over Your Shoulder
The most common hand-off of infor- mation is probably between geologists
and civil engineers, for example in the investigation of a prospective site for the opening of a mine or the construc- tion of a dam, a building, a landll, or a roadway. These two specialties have different traditions and different train- ing (Hatheway, 2005); hence their ap- proaches to the problem are different. Ideally, these approaches should be complementary and reinforce one an- other but differences in communication often arise and may seriously interfere with the successful completion of a pro- ect.
In most instances geological study precedes detailed engineering investi- gation (e.g. Leggett, 1939, 1962, 1979). There is a handoff of information, some- times occurring over a wide time gap, between the geologist and the engineer or the environmental scientist. It is therefore incumbent on the geologist to prepare information in formats and in terminology that are comprehensible to other disciplines.
In the words of Kiersch and James (1991, p. 555), “Many engineers…are confused by geologic reasoning and ter- minology, are prone to discredit geologic reports, and can regard them to be of lit- tle practical value. Likewise, geologists have failed to present their ndings in language understandable to the intend- ed readers, and to explain the signi- cance of a geologic feature or setting.” Serious mistakes are too commonly made. The catastrophic failures of the refuse piles at Aberfan in Wales (Pen- man, 2000) and the Stava tailings dams in Italy (Chandler and Tosatti, 1995) were a result of siting these facilities on top of known springs. The failure of the Malpasset Dam in France was related to insufcient understanding of planes of weakness in metamorphic rocks (James, 1988). The Portuguese Bend landslide complex in southern California that continues to destroy new houses and golf courses was mapped as landslide terrain by the US Geologi- cal Survey as early as 1946 (Hill et al. 2007).
Twenty Ways to
Miscommunicate Geology to Engineers
These communication failures stem from two sources: differences in vocabu- lary and differences in data formats, specically spatial vs. digital data. We address the differences in vocabulary herein. Table 1 lists 20 of the most con- fusing English-language terms used by geologists and geotechnical engineers. Of these, it strikes us that eight are es- pecially likely to cause misunderstand- ing (marked in bold) and therefore merit further discussion. 1. Grain Size Distribution or Grading This is perhaps the most vexing vocabulary discrepancy because the boundaries between the size categories are slightly but signicantly different, the method of representation of the data is opposite, and the qualiers used to describe the distribution have opposing senses. Thorough discussions of grain size analysis in geology are still best found in the classic book by Krumbein and Pettiohn (1938). For engineering, Hunt (2005) is an invaluable resource. The boundaries for grain size catego- ries used by geologists come from the Wentworth classication, whereas en- gineers follow the ASTM classication (ASTM 2009). Consequently, when a ge- ologist refers to “sand,” the material has a grain size between 0.0625 and 2.00 mm; in the ASTM scheme, the range is 0.075 to 4.76 mm. The difference can be signicant. Voight et al. (1981) reported grain size in both systems for debris av- alanche deposits of the 1980 eruption of Mount St. Helens and found that sand- sized grains averaged 42% using the Wentworth classication but 52% using the ASTM classication.
The method of representation of choice for both disciplines is a cumula- tive frequency curve, but it is customary to show percent (%) ner in one case and percent coarser in the other. Further- more, because a sand with a wide range of grain sizes makes a better foundation, an engineer refers to it as “well graded,”
www.aipg.org
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56