Almost all of the facilities that make up our infrastructure are in, on or with earth materials, and geotechnical engineering is the discipline that deals with applications of technology to solve these problems. Examples of facilities in the earth are tunnels, deep foundations and pipelines. Highway pavements and many buildings are supported on the earth. And earth dams, levees, embankments and slopes are constructed with the earth. In addition, many soil-like waste materials are deposited in containment areas. To design these facilities, geotechnical engineers must conduct analyses based on the principles of mechanics and mathematics. These analyses require input data to quantify the properties of the earth materials, and this information is usually obtained from laboratory or field tests.