The soil structure can be defined as the proper geometrical arrangement of particles of soil with respect to each other.
Structure of Soil is one of the major factor which impacts many different properties of soil such as compressibility, permeability and shear strength of soil etc. Mainly there are five types of soil structures which are generally acknowledged.
Types of Soil Structure
There are basically 5 types of soil structures which are recognized in geotechnical engineering.
- Honeycomb Structure
- Single Grained Structure
- Flocculent Structure
- Dispersed Structure
- Composite Soil Structure
Honeycomb Soil Structure
Generally honeycomb structure is mainly observed in soil particles having diameter o.ooo2- 0.02 mm, which are called as silts.
Gravitational as well as surface force plays important role in creating this type of soil structure. Settling of soil grains at contact areas takes place due to this forces.
The soils grains held together and from mini arches which are then relatively joined by large void spaces which are called as honeycomb structure. These structure has high void ratio as large amount of water is enclosed in it.
Single Grained Structure
Single grained structure is observed in coarse-grained soils such as gravels, sands etc. Settling of soil particles takes place separately and individually as due to out of suspension.
All the effective surface forces are negligible as the specific surface of all particles is less.
Flocculent Soil Structure
Flocculent structures is generally observed in clay made of fine particles. These soil structures are formed due to the electrical force between adjacent soil particles at the time of deposition that being attraction force.
Moreover when there is edge contact among the clay platelets, such structures are formed. Addition of concentration of dissolved minerals in water increases the tendency of flocculation.
Dispersed Structure
Disperse soil structures is created when the net electrical forces between adjacent soil particles are repulsive at the time of deposition.
In this structure clay with fine particles can also be seen when there is face to face contact between less or more parallel array.
Composite Soil Structures
Based on the relative proportion of fine grained particles and coarse grained particles, this structure can be divided into two types :
- Cohesive Matrix
- Coarse Grain Skeleton
Cohesive Matrix : In this case clay content is more as compared to coarse grained particles as a result of which bulky particles are not capable to have particle by particle contact.
Coarse Grain Skeleton : In this case the empty spaces in single grained structure which are termed as voids are filled with clay particles.
Also Read : Residual Soil and Transported Soil
Also Read : Particle Size Distribution of Soil