Towards Improved Geotechnical EngineeringGuest Editorial

Having lectured in geomechanics at the S.A. Institute of Technology since 1960 and due to retire in 1988, it is opportune to briefly review some of the advances in geotechnical engineering in that time, and to assess possible directions of improvement in the future.

1960 now seems long ago – well before publication of Geomechanics. At that time, many engineering courses used Terzaghi & Peck’s book as a textbook, with its emphasis on a thorough understanding of geology and physical properties of soil, somewhat theoretical soil mechanics, and a large descriptive section on problems of design and construction, which was full of sensible if somewhat empirical information for practitioners. Areas of geotechnical engineering then fairly well understood were the properties of saturated and compacted soils. However, soil testing laboratories in Australia were few, as was the number of geotechnical engineers.

The period 1960-1988 has seen remarkable advances in all branches of geotechnical enginering. We now have better knowledge of engineering geology and site investigation methods, improved soil and rock testing, major advances in theoretical 30il mechanics, widespread use of computers, and better construction practices. These developments have had a significant impact on the face of Australia; consider examples:

• In all Australian capital cities, the tallest buildings are now on average twice as high as in 1960, reflecting an increased confidence in the art of foundation engineering.
• Many large dams (e.g. Dartmouth) have been successfully constructed, and Australian engineers have developed expertise which is among the best in the world.
• For arid regions of Australia, the last 10 years have seen the emergence of a technology directed at measuring the properties of, and building on, expansive soils. The commercial availability of soil psychrometers has assisted greatly, and· the publication of AS 2870 “Residential Slabs and Footings”, in 1986 was a major advance, particularly because it is the first Code of its type in the world.

One unwelcome development in recent years has been an increase in litigation. It is significant that two guest editorials in the 1st three issues of Australian Geomechanics have been on this subject. the las tone, by Ron Herriot 13, June 1987), focussed on what many engineers must regard as unreasonable features of the Australian law, and gave some cautionary advice for geotechnical engineers who become involved with legal problems. Apart from the written law, it is observed that members of the legal profession are accustomed to think in terms of the adversary system of “right” or “wrong”, whereas the objective of engineers is to design and construct having regard to both acceptable risks and costs. Under the circumstances, it is not surprising that many geotechnical engineers are adopting conservative designs.

While advances since 1960 (that is, in the past 28 years) have been substantial, the writer is to believe that the next 28 years will see developments which are equally significant. This view is based on the large number of students taking postgraduate courses in geomechanics, the greatly increased number of practitioners, the large number of papers being published, and demands for good professional advice on a wide range of geotechnical problems. Four specific areas where in existing knowledge are seen as likely are:

• Engineering geology, where more extensive regional field data is becoming available. Perhaps the most notable recent development is in relation to calcareous sediments used as foundations for off-shore platforms in the oil industry.
• Soil testing procedures, particularly for soils which are unsaturated and/or expansive. For example, at present laboratory technology involving soil suction is still rather basic.
• Theoretical soil mechanics may be expected to continue to undergo modification and improvement, hopefully in the light of experience based on the performance of actual structures. For example, it is difficult at present to estimate the settlement of large buildings with a high level of accuracy.
• The application of computing to design problems. It is true that the existing precision of analysis by computers far exceeds the precision of data obtainable by soil or rock testing. Nevertheless, there appears to be scope to improve the mathematical model on which much computing is at present based. For example, in the writer’s home city of… designing footings on expansive soils. But all existing methods adopt a simplified mathematical model which does not necessarily represent the worst field conditions.

Finally, there is one area where the writer would hope to see reduced activity, and that is in litigation. Engineers who become involved as professional witnesses should have regard to the excellent series of “Miller’s Tales” in Engineers Australia, written by Dr. Peter Miller. Basically, engineers should be concerned only with presenting the true facts, even when such facts may not be in their client’s interests. This may result in some clients being lost, but it is suggested that the objective should not necessarily be to retain clients in litigation matters, and it is essential for all members of. the profession to be truthful and technically correct at all times.