Construction of Embankments
Embankments are man-made structures used to redirect water or transportation services. There are several kinds of embankments that are used in different situations. Some embankments are very large and well-known, such as the Thames Embankment along the north side of the Thames River in London. Other embankments are small and homemade and can simply serve the purpose of diverting overflow rainwater from a lawn or garden.
Definition of Embankment
An embankment is a levee, dike or other artificial bank or barrier used to hold back or redirect water in order to prevent flooding from a river, lake, sea or other water source. Embankments can also be constructed to support transportation services, such as roadways, railways and canals. In the case of roadways and railways, embankments often raise the level of the transportation to keep them removed from flooding or other natural dangers.
Embankment Construction Materials
Embankments are traditionally made from stones, rocks, earth or a combination of the three. In the case of rock embankments, large rocks of a volume of over .5 cubic yard or boulders are generally used. The large spaces left in rock embankments are filled with smaller stones or earth, creating a solid embankment.
Depending on the size and use of an embankment, the amount of earth or rock used to fill an embankment will vary. The important thing is to construct an embankment so it won't be affected by surface erosion and begin to deteriorate.
Transportation embankments are built to support transportation. Normally built to allow for a straight, flat and uninterrupted path of transportation, these embankments are in many ways the opposite of a transportation cutting, where a section of a mountain or hill is cut to make room for a road or railway. In fact, material gathered from transportation cuttings is often used in the construction of transportation embankments.
Embankment dams are large, man-made water barriers typically make from various compositions of soil, sand, clay and rock. Unlike smaller embankments, embankment dams often have a waterproof covering to make the dam especially impervious to seepage or erosion. Some large embankment dams in the U.S. include New Cornelia Tailings Dam in Arizona and Fort Peck Dam in Montana.
Embankment Density Controls
In order for an embankment to function properly, certain density controls must be taken into consideration during construction. These controls include compacting the dry density of the embankment to at least 95 percent of its maximum density, keeping the moisture content within -2 and +1 percentage points of the ideal moisture level, and removing excess moisture through aeration, among other measures. For more information on embankment density control, see Resources.