Reviews in Engineering Geology
This is the second in a series of volumes prepared by the Geological Society of America Division on Engineering Geology designed to summarize the states of knowledge on various aspects of the application of geology to engineering problems. Through an unfortunate series of delays, publication of the book was delayed several years beyond the completion of the contained papers. The geologic principles are still sound, however, and are certain to be useful to the practicing engineering geologist. Nine papers review the following subjects: foundations for heavy structures; geology and pedology in highway soil engineering; clay as a canal sealant; Portland cement and concrete; pozzolan; geocryology and engineering; land subsidence due to withdrawal of fluids; land subsidence due to the application of water; and geologic settings of subsidence.
During the first half of the present century, a warming trend manifested in the arctic regions produced a decrease in glacier sizes and a northward recession of the southern boundary of the perennially frozen ground. This climatic amelioration had great significance not only from the geological and engineering viewpoint but also from the viewpoint of agronomical and animal production, forestry, fisheries, and other activities.
In the study of the complex relationship among climate, soil, and vegetation, the effects of climatic fluctuation need to be considered. This climatic fluctuation is important also from the viewpoint of process activity, for as the climate improves, some frost-effect features become inactive. These processes by which cryoturbation features become inactive and are kept in the geological record are not well known. They are important, however, in order to understand the geological significance of frost phenomena, to determine cryoturbation facies, and to assess fossil forms.
In view of this climatic fluctuation, the use for design purposes of the coldest year in a 30-year period is questionable. It seems more advantageous to use a forecasted temperature for the life expectancy of the project. A program of ground temperatures taken from satellites was not made in relation to developments in arctic regions. Such a program has direct benefits for researchers and planners because ground temperatures taken in places are costly and in remote areas are almost impossible to obtain. The advantage of satellite information is that it can be obtained in large areas simultaneously.
Ground ice is an important phenomenon from both the geological and engineering viewpoint. The origin of Alaska's large bodies of foliated ground ice is still not known. Considering its geographical extension, thickness, and location in an area of future developments, a thorough study is highly desirable.
As more data is gathered on rates of ground motion in solifluction slopes, it is observed that maximum values are not greater than 30 cm per year. Because of the lack of cryofragmentation values, a balance between the amount broken and the amount removed cannot be presented.
The determination of frost-heaving susceptibility is done under one freezing test at a rate of freezing equivalent to the average rate of freezing in nature. Two shortcomings, however, are observed. (1) The rate of thawing is not considered, but it is important because it liberates water from the melting ice lenses. Under a fast rate of thawing, water will be available at a certain time in a determined level, making the soil more likely to move. (2) Particle sorting, observed in nature and in laboratory experiments, is not yet considered in the test for frost behavior. The future will tell if it will be more convenient to distinguish between frost-heaving-susceptible soils and frost-sorting-susceptible soils.
An interdisciplinary international conference related to geology, soils, plants, animals, and their relationship to climate and changes of climate of the cold regions, using modern satellite information, would give a wealth of information for science and technology.