chapter 6
Hydrostatic Water in Soils and Rocks
From previous discussions on the Atterberg limits, classification of soils, geologic processes, and Soil and rock structures, you should now realize that the presence of water in soils and rocks is very important Water very strongly affects the engineering behavior of most soils, especially fine-grained soils, as well as many rock masses. Water is an important factor in most geotechnical engineering design and construction projects. A few examples include capillarity, swelling, and frost action in soils, discussed in this chapter, and seepage of water through dams and levees and toward wells, as discussed in Chapter 7. As an indication of the practical importance of water in geotechnical engineering, it has been estimated that more people have lost their lives as a result of failures of dams and levees due to seepage and “piping (Chapter 7) than to all the other failures of civil engineering works combined. In North America damage from swelling (expansive) soils causes a greater economic loss annually than floods, hurricanes, tornadoes, and earthquakes combined.
In general, water in soils can be thought of as either static or dynamic. The groundwater table,
even though it actually fluctuates throughout the year, is considered to be static for most engineering purposes. Adsorbed water (Chapter 4) is generally static. Similarly, capillary water is usually taken to be
static, although it too can fluctuate, depending on climatic conditions and other factors In this chapter
we shall concentrate on hydrostatic water problems in geotechnical engineering.