Phase Diagram of Soil | Properties of Soil | Soil Mechanics

  Phase Diagram of Soil  

Soil is a three-phase system that consists of solid, liquid & gaseous matter, that do not occupy separate spaces, but are blended with each other in a definite proportion, which in turn governs the properties 0f soil.

Solids in soil may consist of inorganic minerals ( Liquid-Water, Gases-Air) & organic matter.

Solids:

1. Inorganic Minerals (Liquid- Water, Gases- Air.)
2. Organic Matter

Three Phase System of Soil

Soil is a three-phase system. If it consists of solid, liquid & gaseous matter, that do not occupy separate spaces but are blended with each other in a definite proportion

V=  Vv + Vs

V= ( Va+ Vw ) + Vs

W= Wv + Ws

W= ( Wa + Ww ) + Ws

ρair = 1.2 kg/m³

ρwater = 1000 kg/m³

ρsolids = 2600 kg/m³

ρsolids > ρwater >>> ρair

Wa <<< Ww or Ws ⇒ hence it can be neglected.

But  Va ≮  Vw or Vs, the volume of air can’t be neglected.

W = Ww + Ws.

But   V ≠ Vw +Vs.

Two Phase System of Soil

In some limiting cases, it can be represented as a two-phase system also. If it consists of solid & air or solid & water, that do not occupy separate spaces but are blended with each other in a definite proportion.

1. Dry soil – Solid, Air.
2. Saturated soil – Solid, Water.