What Is Coefficient Of Uniformity Of Soil?


It is the parameter estimated using the gradation curve through sieve analysis. The diameter taken from gradation curve for which the 10% particles are finer is known as effective size. … When the value of C C is in between 1 and 3, the sand or gravel is said to be well graded.

How do you calculate uniformity coefficient?

Uniformity Coefficient (UC) – This is defined as a ratio and is calculated as the size opening that will just pass 60% of the sand (d60 value) divided by the size opening that will just pass 10% of the sand sample (d10 value).

What is the meaning of D60 and D30?

D60 – 60 % of the soil particles are finer than this size. D30 – 30% of the particles are finer than this size. … For example, if you have 100 particles of diameter ranging from 1 mm to 100 mm, D60 is 61 mm (below which 60% of particles are there).

How do you determine D10 D30 and D60?

The particle diameters defining 10%, 30%, and 60% finer from the grain-size distribution curve are estimated as: D10 = 0.14 mm , D30 = 0.27 mm, and D60 = 0.42 mm.

What does D10 D50 and D90 mean?

D10: The portion of particles with diameters smaller than this value is 10% D50: The portions of particles with diameters smaller and larger than this value are 50%. Also known as the median diameter. D90: The portion of particles with diameters below this value is 90%.

What is the formula of coefficient of curvature?

Cc = (D30)2/D60.D10

Where, D60 = Size of the particle corresponding to 60% finer. D30 = Size of particle corresponding to 30% finer. D10 = Size of the particle corresponding to 10% finer.

What is the formula of coefficient of permeability?

1.1 Permeability coefficient. where P = the differential pressure across the medium (Pa): L = the depth or thickness of the bed or medium (m); Q = the volumetric flow rate of fluid (m3/s): μ = the kinematic viscosity of the fluid (Ns/m2): A = area occupied by flow (m2).

What is the coefficient of permeability?

The coefficient of permeability (K) is the velocity in meters or centimeters per second of water through soils. Fine-grained soils such as clays might have values of around 10-8meters/sec or lower, or a sand and gravel formation could be 10-4meters/sec or higher.

Where the coefficient of consolidation is used for calculating?

Time rate of settlement.

What is uniformity coefficient of sand?

The uniformity coefficient describes how similar in size the sand particles are. The silt content is the percentage of sand with a diameter < 0.1 mm. If your effective size is below 0.15 mm, that means too much of the sand is very small sand particles.

What is the most basic classification of soil?

According to the USCS classification, soil is divided into: coarse grained soil, fine-grained soil, and highly organic soil. The particle size distribution of soil and consistency limits are used in classification of soils.

What is the toughness index?

Toughness index is defined as the ratio of plasticity index (IP) of the soil to the flow index (IF) of the soil. Toughness index varies between 0 to 3. This gives us an idea of shear strength of soil at its plastic limit.

What is the unit of coefficient of consolidation?

Coefficient of consolidation is the rate at which saturated soil undergoes consolidation. It can be only measured in laboratory. Time factor is given by T v = C v t d 2 . From this equation, the unit of coefficient of consolidation comes out to be cm2/sec.


What are the factors affecting coefficient of permeability?

The factors that affect the coefficient of permeability for a given soil are particle size distribu- tion (grading curve), void ratio, level of saturation, soil structure, and soil imperfections or discontinu- ities . The coefficient of permeability increases significantly with increase in the void ratio.

What is the unit of coefficient of absolute permeability k )?

Explanation: Since K has the dimension of area (i.e. = ), the unit of K is m2. We can find that coefficient of permeability is independent of the properties of permeant (i.e. water) and it depends solely on the properties of soil mass.

Can uniformity coefficient be less than 1?

The uniformity coefficient (Cu) is defined as the ratio of D60 to D10. A value of Cu greater than 4 to 6 classifies the soil as well graded. When Cu is less than 4, it is classified as poorly graded or uniformly graded soil. Uniformly graded soil has identical particles with Cu value approximately equal to 1.

What is coefficient of concavity?

To analyze the profile deviation, it is proposed to use the concavity coefficient, which is the ratio of the cross-sectional area of the actual profile to the normative profile values.

What is D90?

D90 is particle size distribution D90, it represents the particle diameter corresponding to 90% cumulative (from 0 to 100%) undersize particle size distribution.

What is a D50 value?

Particle Size Distribution D50 is also known as the median diameter or the medium value of the particle size distribution, it is the value of the particle diameter at 50% in the cumulative distribution. It is one of an important parameter characterizing particle size.

What is D90 in PSD?

In general, a narrow PSD of pharmaceutical powders is desired. … D10, D50, or D90 is defined as the size value corresponding to cumulative size distribution at 10%, 50%, or 90%, which represents the size of particles below which 10%, 50%, or 90% of the sample lies.

Is percent finer the same as percent passing?

This means that 18.2% of the material passed through that sieve, and 81.8% (which is 100% – 18.2%, which you can see in the “Cumulative Retained” column) was “caught”, or retained, by that sieve. “% Finer” represents the percentage of material of the total sample (100%) that will pass through the current sieve.

What does uniformity coefficient mean?

uniformity coefficient (u-ni-form’-i-ty). A numerical expression of the variety in particle sizes in mixed natural soils, defined as the ratio of the sieve size through which 60% (by weight) of the material passes to the sieve size that allows 10% of the material to pass.

What is represent by D10?

Explanation: The D10 represents a size, in mm such that 10% of the particle is finer than D10 size. … Explanation: Coefficient of the curvature Cc represent the shape of the particle size curve given by CC = (D40)2/D10×D30.