Also called shear resistance angle. When sand is dropped, a mountain forms, and the angle at which it forms is called the angle of repose, which roughly matches the angle of internal friction. Example 2) Shear failure of non-cohesive soil (typical example, dry sand) occurs when the stress ratio τ / σ is a predetermined value (tanφ : The most important factor is the internal friction angle φ, and even a small change in φ will have a large effect on tan (45° + φ/2) (see Table 8.1). From the above, compacting sand and gravel increases γ and φ.
UT Austin Sorority and Fraternity Life Info Guide 23.24 by UT Austin
1.1.1 Classification of strength constants, etc. Strength constants represent the mechanical properties of soil and are divided into cohesion (c or c') and shear resistance angle (φ or φ'). Note that when performing stability calculations, in addition to the strength constant, the unit body is also used.
