Soil Mechanics: Mechanical Analysis of Soil and Particle-Size Distribution - Prof. Mante, Slides of Soil Mechanics and Foundations

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SOIL MECHANICS‐LECTURE Content:CHAPTER 2: Origin of Soil and Grain Size2.7: Mechanical Analysis of Soil2.8: Particle‐Size Distribution Curve

jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.7: Mechanical Analysis of Soil •^ Mechanical analysis

• is the determination of the size range of particles present in a soil, expressed as a

percentage of the total dry

weight. • Two methods generally are used to find the

Particle‐Size Distribution

of soil:^ oSieve Analysis

• for particle sizes larger than 0.075 mm in diameter. oHydrometer Analysis - for particle sizes smaller than 0.075 mm in diameter.

jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.7: Mechanical Analysis of Soil •^ Example Sieve Analysis

jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.7: Mechanical Analysis of Soil •^ Example Sieve Analysis

jbmamburam_CIEN 3113_2nd Sem AY 2024‐ R^ = (M/ ∑M) x 100%n^ n^ R^1 , R^2 ,... R^ n

FF= 100% ‐ R^1 11 , FF= F– R^2 1 22 ,... Fn F= F– R^ n^ (n‐1)^ n

2.7: Mechanical Analysis of Soil •^ Hydrometer Analysis

is based on the principle of sedimentation of soil grains in water. When a

soil specimen is dispersed in water

, the

particles^ settle at different velocities, depending on their shape,size, weight, and the viscosity of the water. It is assumed that all thesoil particles are spheres.

jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.7: Mechanical Analysis of Soil •^ Hydrometer Analysis

jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.7: Mechanical Analysis of Soil •^ Hydrometer Analysis

jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.7: Mechanical Analysis of Soil •^ Hydrometer Analysis

jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.7: Mechanical Analysis of Soil •^ Example Hydrometer Analysis

jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.7: Mechanical Analysis of Soil •^ Example Hydrometer Analysis

jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.8: Particle‐Size Distribution Curve 1.^ Effective size (D

):^ This parameter is the diameter in the particle‐ 10 size distribution curve

corresponding to 10% finer

. The effective

size of a granular soil is a

good measure to estimate the hydraulic conductivity and drainage through soil

2.^ Uniformity coefficient (C

):^ This parameter is defined asu jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.8: Particle‐Size Distribution Curve 3.^ Coefficient of gradation (C

):c

4.^ Sorting coefficient (S

):This parameter is another measure of 0 uniformity and is generally encountered in geologic works andexpressed as

jbmamburam_CIEN 3113_2nd Sem AY 2024‐

2.8: Particle‐Size Distribution Curve •^ Different types of particle‐size distribution curves^ oPoorly Graded (Curve I)

• most of the soil grains are the same size. oWell Graded (Curve II)
  • soil in which the particle sizes are. distributed over a wide range.^ Gravels^ (

C^ ≈4)u^ Sand (C ≈ 6)u oGap Graded (Curve III)

• a soil might have a combination of two or more uniformly graded fractions.

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2.8: Particle‐Size Distribution Curve •^ Sample Problem

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