Particle Size Range and its Measure

Particle size range is a critical property of soil that affects its physical and mechanical properties. The particle size range of soil is measured using various indices, including the effective size, uniformity coefficient, and coefficient of curvature.

Uniformity Coefficient

The uniformity coefficient (UC) is a measure of the particle size range of soil. It is calculated as the ratio of the particle size that passes through 60% of the soil sample (D60) to the particle size that passes through 10% of the sample (D10).

UC = D60/D10

The UC value of a soil sample ranges from 0 to infinity. A soil sample with a UC value of 1 has a uniform particle size distribution, while a soil sample with a UC value greater than 4 is considered to have a wide particle size distribution.

Significance of Uniformity Coefficient

The uniformity coefficient is an essential parameter in soil mechanics and geotechnical engineering. It helps to determine the engineering properties of soil, such as its permeability, compressibility, and shear strength.

The following are some of the significance of uniformity coefficient:

- The UC value helps to classify soils into different groups based on their particle size distribution. For example, soils with UC values less than 2 are considered well-graded, while soils with UC values greater than 6 are poorly graded.
- The UC value is used to design filters and drainage systems for retaining walls, dams, and other geotechnical structures.
- The UC value influences the effectiveness of soil stabilization techniques, such as lime and cement stabilization. Soils with high UC values may require more stabilizing agents to achieve the desired strength and stability.

Conclusion

In summary, the uniformity coefficient is a measure of the particle size range of soil. It is calculated as the ratio of the particle size that passes through 60% of the soil sample (D60) to the particle size that passes through 10% of the sample (D10). The UC value helps to determine the engineering properties of soil and is used in the design of geotechnical structures and soil stabilization techniques.