Transportation of Soils - Geotechnical Engineering

The soils can be transported from one place to another by certain agents like water, wind, ice and gravity. Based on which, soils can be classified as:

  1. Water Transported Soils
  2. Wind Transported Soils
  3. Glacier-Deposited Soils
  4. Gravity-Deposited Soils
  5. Soils Transported by Combined Action

1. Water Transported Soils

  • The soils can be transported by water in sea or in lakes. The soils transported by water are called as alluvial soils.
  • The soils transported by ocean or seawater is called as marine deposits.
  • The soils deposited in lakes are called as lacustrine deposits.

Fig.1. Alluvial Deposits

As shown in figure-1 above, based on the behaviour of flowing water, the nature of alluvial deposits differs. Swift running water takes large quantity of soils wither by suspension or by rolling along the bed. The water running along the hills erodes the ground and deposit soil in the valleys.

The size of the soil particles taken by the water depends on the velocity of the water. Large boulders and gravels are taken by large velocity water. When velocity reduces, they deposits the coarser aggregates. Finer particles are later moved by decreased velocity and deposit it with the reduction in velocity. When the velocity finally moves to zero, a delta is formed at the end.

2. Wind Transported Soils

  • These deposits carried by wind are called as Aeolian deposits.
  • Loess is defined as the silt deposit made by the winds. It possess low density and high compressibility. Such soils have low density and compressibility.

3. Glacier - Deposited Soils

With the development of glaciers and movement of the same, it takes soils along with it. The soils are taken far away from the original positions. They take fine aggregates to huge boulders.
  • Drifts are deposits made by glaciers directly or indirectly.
  • Till is the deposits made by the melting of glaciers.

4. Gravity Deposited Soils

Soils that are transported to short distance under the action of gravity is called as gravity deposited soils. Colluvial or talus soils comes under this category. Rocks present in cliffs or steep slopes fall from higher elevation under the action of gravitational force.

Talus is a combination of irregular coarse particles. It is a good source of broken rock pieces and coarse grained soil.

5. Soil Transported  by combined Action

Two or more agents can jointly involve in the transportation of soils.

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