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Angle of Internal Friction

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Encyclopedia of Engineering Geology

Part of the book series: Encyclopedia of Earth Sciences Series ((EESS))


The angle of internal friction is a physical property of earth materials or the slope of a linear representation of the shear strength of earth materials.

Earth materials that are unconsolidated and uncemented typically are called soil by engineers and geologist and may be called sediment by geologists. Soil consists of grains of minerals or rock fragments in a range of sizes (mm to m) from very fine to very coarse (clay, silt, sand, gravel, cobble, and boulder-size). Grains that are chemically and mechanically separate from each other form a mass that can be excavated with relative ease, and the excavated material can be placed in a pile that attains a conical shape with slopes that are called the angle of repose (Fig. 1). The angle of repose is a representation of the angle of internal friction; however, it tends to be governed by grain shape such that the slopes of most piles of loose, dry grains of natural soil are in the range of 28° to 34°. A pile of angular...

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  • Keaton JR, Ponnaboyina H (2014) Selection of geotechnical parameters using the statistics of small samples. In: Abu-Farsakh, M, Yu, X, Hoyos, LR (eds) Geo-characterization and modeling for sustainability. ASCE Geo-Congress 2014, February 23-26, 2014, Atlanta, Georgia geotechnical special publication, vol 234. pp 1532–1541 ISBN (print): 9780784413272;

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Correspondence to Jeffrey R. Keaton .

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Keaton, J.R. (2017). Angle of Internal Friction. In: Bobrowsky, P., Marker, B. (eds) Encyclopedia of Engineering Geology. Encyclopedia of Earth Sciences Series. Springer, Cham.

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  • Print ISBN: 978-3-319-12127-7

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