Soil Classification Reliable Security Information（土壤分类可靠的安全信息）.pdfVIP

FM 5-410 CHAPTER 5 S o i l C l a s s i f i c a t i o n Early attempts to classify soils were based involved in soil behavior and the variety of primarily on grain size. These are the tex- soil problems encountered. Considerable tural classification systems. In 1908, a progress has been made toward this goal, par- system that recognized other factors was ticularly in relationship to soil problems developed by Atterberg in Sweden and encountered in highway and airport en- primarily used for agricultural purposes. gineering. Soil classification should not be Somewhat later, a similar system was regarded as an end in itself but as a tool developed and used by the Swedish Geotech- to further your knowledge of soil behavior. nical Commission. In the United States, the Bureau of Public Roads System was Section I. Unified Soil developed in the late twenties and was in Classification System widespread use by highway agencies by the middle thirties. This system has been revised over time and is widely used today. The Air- SOIL CATEGORIES fieid Classification System was developed by Soils seldom exist in nature separately as Professor Arthur Casagrande of Harvard sand, gravel, or any other single component. University during World War II. A modifica- Usually they occur as mixtures with varying tion of this system, the USCS, was adopted by proportions of particles of different sizes. the US Army Corps of Engineers and the Each component contributes its charac- Bureau of Reclamation in January 1952. A teristics to the mixture. The USCS is based number of other soil classification systems on the characteristics of the so