ABSTRACT
The Earth’s surface is defined, for the purpose of this chapter, as the semi-solid to solid soil or rock surface that is of interest to the geotechnical engineer, in pursuit of his professional activities. The depth of interest may be as little as a metre or two, as in the case in pavement engineering, or may extend to depths of several thousand metres, for example in deep mining. (For example, the author has a long-term involvement in assessing drying rates of tailings deposited on the surfaces of hydraulic fill tailings storages at an elevation of 1700 m above sea level, as well as the compression resistance of unsaturated tailings backfill supports in the workings of the world’s deepest mine at 4000 m below surface or 2300 m below sea level.)
Interactions between the atmosphere and the geosphere have always been important to civil engineers, and particularly to geotechnical engineers. Certain of these interactions can be rapid and catastrophic, resulting in the failure of structures such as dams and bridges, in loss of life and in widespread environmental devastation. Other interactions can be slow and insidious, but still destructive and costly in the long term, e.g. the effects that swelling or shrinking clays have on buildings on shallow foundations.
