Question

Explain all the modes of occurrence of water in the soil. Also, explain shrink, swell, bulking of sand and Frost action w.r.t soil mechanics (how it impacts or effects structures)

Answer 1

There are four types of water present in soil.

1)Gravitational water-This water is present in soil mass due to external rainfall or precipitation. In this case the surface layer of soil gets partially saturated.

2)Capillary water-This water is present in soil capillary pores. This water is bound to soil by force of surface tension.

3)Hygroscopic water-This water is present on the surface of soil solids.It is bound to soil solids by adhesive force (adsorption force)between water and soil particles.

4)Structural water-This water is bound with soil at molecular level.It is also called molecular bounded water.This water can not be removed by oven drying.

Shrink and swell- Shrink is the property of clay. By virtue of this the clay shrink when dry.

Swelling is also the property of clay.The soil starts swelling that is increase in volume on wetting.

A soil with high Swelling and shrinkage is avoided.

Bulking of sand is the property of sand . At 5 to 6 percentage of water volume of dry sand increases due to absorption of water.This phenomenon is called bulking of sand.

Frost action-Frost action results in cyclic freeze and thaw phenomenon. Due to freeze and thaw weathering of soil surface starts. So strength of soil starts decreasing due to frost action. It affects the structure by weathering process.