Shear strength of coarse fragmental soils

Abstract

1. The construction of high earth and rock dams requires that investigators obtain exact data on the shear resistance and deformative properties of coarse-fragmental soils. 2. Investigations carried out in recent years here and abroad have made it possible to establish the following: a) The angle of internal friction of coarse-fragmental soils largely depends on the density of packing, soil stresses, and size of the particles composing the soil; b) The angle of internal friction of coarse-fragmental soil can exceed numerically its angle of repose and is within limits up to 54° and sometimes higher; c) Investigations of shear strength can be conducted both by shear instruments and by consolidometers, provided Dinst/dfrac≥5; d) One should try to investigate coarse-fragmental soils of natural granular composition using field instruments. 3. The angle of internal friction of coarse-fragmental materials decreases with an increase of normal stresses and to a greater degree for rock than for gravel in the same range of stresses. 4. Further investigations of the shear strength of coarse-fragmental soils should be aimed at perfecting large devices (preference should be given to consolidometers) and methods of investigation.