Development of engineering geology

INTRODUCTION: While ancient man must have had some intuitive knowledge of geology, as evidenced by the feats of mining and civil engineering performed in the distant past, the present science of geology owes much of its origin to the civil engineers working in the eighteenth century. These engineers, while constructing the major engineering works associated with the industrial revolution, had the opportunity to view and explore excavations in rocks and soils. Some, intrigued by what they saw, began to speculate on the origin and nature of rocks, and the relationships between similar rocks found in different places. Their ideas and theories, based on the practical application of their subject, formed the groundwork for the development of geology as a science. Engineers such as Lewis Evans (1700–1756) in America, William Smith (1769–1839) in England, Pierre Cordier (1777–1862) in France and many others were the ‘fathers’ of Geology.

Their interest in geology often stemmed from a ‘need to know’. They were confronted with real engineering problems which could only be solved with the help of both knowledge and understanding of the ground conditions with which they were confronted. In the later nineteenth century both geology and engineering advanced, geology becoming a more-or-less respectable natural philosophy forming part of the education considered suitable for well brought up young ladies. Engineering, characterized by the canal and railway construction carried out by the ‘navvy’, on the other hand, remained as an eminently practical subject. The theoretical understanding of engineering was driven by practical engineering problems. The geological knowledge of the engineer, confronted by increasingly difficult engineering challenges, did not progress as rapidly as geology, advanced as a science under the leadership of geologists such as James Dana (1813–1895) in America, Albert Heim (1849–1937) in Switzerland and Sir Archibald Geikie (1835–1924) in Britain. Thus, by the end of the nineteenth century the majority of civil engineers knew relatively little about geology, and very few geologists were concerned about, or interested in, its engineering applications.

This widening division between geology and engineering was partly bridged in the nineteenth and early twentieth century by the development of soil mechanics by engineers such as Charles Coulomb and Macquorn  Rankine, who developed methods of calculating the deformations of earth masses under the stresses imposed by engineering works. The great leap forward may be considered to have taken place with the publication of “Erdbaumechanik” by Karl Terzaghi in 1925, which brought together old knowledge, and added new theory and experience to establish soil mechanics in its own right as a discipline within the field of civil engineering. Subsequent publications by Terzaghi and others have continued to recognize a clear understanding of the fundamental importance of geological conditions in civil engineering design and construction. However, this appreciation has not proved to be universal and many engineers continued to rely on inadequate geological knowledge, or over-simplified ground models.

Aims of Engineering Geology: Every discipline must have an aim and purpose. The Association of Engineering Geologistsincludes in its 2000 Annual Report and Directory the following statement:“Engineering Geology is defined by the Association of Engineering Geologists as the disciplineof applying geologic data, techniques, and principles to the study both of a) naturally occurringrock and soil materials, and surface and sub-surface fluids and b) the interaction of introducedmaterials and processes with the geologic environment, so that geologic factors affecting the planning,design, construction, operation and maintenance of engineering structures (fixed works)and the development, protection and remediation of ground-water resources are adequatelyrecognized, interpreted and presented for use in engineering and related practice.”The IAEG has produced a statement on similar lines which sets out the redefinitionof its mission in 1998 as The International Association for Engineering Geologyand the Environment.The exact phraseology, and interpretation, of such statements varies from countryto country depending upon national and local practice. Thus many “engineering geologists”are essentially geologists who deliver basic geological data to engineers, withoutinterpretation. At the other end of the scale some engineering geologists mightdesign foundations and slope stabilization, thereby spending much of their time asgeotechnical engineers. Much clearly depends on the training and experience of thegeologist involved, and the attitudes of the organization in which he or she is employed.A particular problem lies in the field of hydrogeology (or geohydrology). In somecountries much of exploration for sources of potable water is carried out by engineeringgeologists. In other countries this is undertaken by specialized hydro geologists whoare quite separate from their engineering geological brethren. Again the national culture of science and engineering influences the trend. Engineering geology may exist under, or be a part of, other titles, such as “geological engineering”, “geotechnical engineering”, “earth science engineering”, “environmental geology”, “and engineering geomorphology” and so on. If there is a difference in the content of the disciplines described under these names it probably lies in the training and experience of the practitioner. Engineering geology is taught in some countries as a postgraduate (Masters) degree course following on from a first degree or other qualification. If the first degree is in geology then the product after the Master’s degree will be that of an engineering geologist; if the first degree is in engineering then the product may be considered as a geotechnical engineer.