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Constant volume friction angle of granular materials

University of British Columbia

The postulate that the constant volume friction angle Φ[sub cv] of a granular material is unique is verified experimentally. The constant volume friction angle of a wide spectrum of granular granular materials is measured using the ring shear device, enabling the material to be sheared to large, in fact unlimited strains at which 0cv is mobilized. Granular materials tested were composed of particles ranging from minerals to metals. The effects of confining pressure, initial packing density, particle size, gradation and particle shape on the value of Φ[sub cv] are studied. The possible influence of the presence of pore water is also investigated. The test results indicate that for a given material, Φ[sub cv] is independent of confining pressure, initial packing density and particle size. Neither particle crushing nor change in shape of the particle had any noticeable effect on the observed value of Φ[sub cv]. These experimental results suggest that the constant volume friction angle is a fundamental property of a granular material which is dependent only on the mineral constituency of the material. A comparison of Φ[sub cv] and the friction angle mobilized at the point of maximum contraction in drained shear (a transient constant volume state) as well as the friction angle mobilized at phase transformation state in undrained shear (a transient constant pore pressure state) is also made, in an attempt to seek a broader fundamental significance of Φ[sub cv].

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2010-07-12

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http://hdl.handle.net/2429/26342

Civil Engineering

University of British Columbia

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