EM 1110-2-1100 (Part III)
30 Apr 02
A. Typical Engineering Values (from Terzaghi and Peck (1967), Table 6.3)
Dry Bulk Density, kg/m3
Saturated Bulk Density, kg/m3
Soft, very organic
B. Natural Surface Soils (from Daly, Manger, and Clark (1966), Table 4-4)
No. of Samples
Mean Porosity, %
Saturated Bulk Density,
Cape May sand spits
Very Fine Sand
C. Laboratory Soils (from Johnson and Olhoeft (1984), Table 4)
Dry Bulk Density "fluffed" kg/m3
Dry Bulk Density "tapped", kg/m3
Note: Data for loess in Parts B and C are representative of silty material.
d. Angle of repose.
(1) When a dry sand-size sediment is poured onto a flat surface, it will form a cone-shaped mound. The
slope of the surface of the cone (or dune) at the moment of avalanching is called the angle of repose. The
angle of repose concept is of interest to coastal engineers for several reasons, including the stability of rubble-
mound breakwaters and the modeling of sediment transport.
(2) The angle of repose is a function of grain shape; it increases with increasing grain irregularity. This
is easy to see in the extreme case: a pile of jacks (or interlocking breakwater armor units) will stack at a much
steeper angle than a pile of ball bearings. Several workers, including Lane (1955), Simons and Albertson
(1960), Allen (1970), Cornforth (1973), Statham (1974), and Simons and Senturk (1977) have looked at the
variation of the angle of repose in relationship to various sediment characteristics.
(3) Bagnold used the relationship between the shear forces, the normal forces, and the angle of repose
to develop his energetics-based sediment transport model. He reasoned that the amount of sediment by
weight at the top of a bed that can be supported in an elevated state and then be transported is related to the
applied shear stress of the overlying (moving) fluid by the tangent of the angle of repose. Bagnold's concept
forms the basis of many of the sediment transport models most frequently used by coastal engineers. For
further discussion, see Bagnold (1963), (1966), Bailard and Inman (1979), and Bailard (1981).
Coastal Sediment Properties