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If the soil particles in a sample are predominantly in a relatively narrow range of sizes, the sample is uniformly graded. If a soil sample has distinct gaps in the gradation curve, e.g., a mixture of gravel and fine sand, with no coarse sand, the sample may be gap graded. Uniformly graded and gap graded soils are both considered to be poorly ...
Internal erosion is the formation of voids within a soil caused by the removal of material by seepage. [1] It is the second most common cause of failure in levees and one of the leading causes of failures in earth dams, [2] responsible for about half of embankment dam failures.
Soil erosion is the denudation or wearing away of the upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, air (wind), plants, and animals (including humans).
Typically, porous soils are removed before compacted clay is applied to the bed and sides of a canal. [3] Another simple method of canal lining with soils entails applying a layer of compacted silt on top of the subgrade of the canal. [3] The use of soils as canal linings is efficient for controlling seepage, but not effective against weed ...
Using our spheres as a model, this is the same as injecting (or withdrawing) water between the spheres. If water is being injected, the seepage force acts to separate the spheres and reduces the effective stress. Thus, the soil mass becomes weaker. If water is being withdrawn, the spheres are forced together and the effective stress increases. [11]
Potential problems, such as the possibility of increased presence of disease in recycle water, have only begun to be investigated. One of the disadvantages of sub-irrigated closed systems, such like Earth Boxes and sub-irrigated planters , is that soluble salts cannot be flushed into the lower soil profile and build up over time.
Dispersion is a process that occurs in soils that are particularly vulnerable to erosion by water. In soil layers where clays are saturated with sodium ions ("sodic soils"), soil can break down very easily into fine particles and wash away. This can lead to a variety of soil and water quality problems, including:
In the instances where clay is used as the impervious material, the dam is referred to as a "composite" dam. To prevent internal erosion of clay into the rock fill due to seepage forces, the core is separated using a filter. Filters are specifically graded soil designed to prevent the migration of fine grain soil particles.