Learning Objectives:

• Understand the fundamental concept of soil index properties, including concepts like grain size distribution, specific gravity, and water content, and their importance in soil engineering.
• Be able to calculate and interpret key soil mass-volume relationships, such as dry density, void ratio, porosity, and degree of saturation.
• Understand the Atterberg limits (liquid limit, plastic limit, and shrinkage limit) and their significance in classifying soils. Be able to perform and interpret tests for these limits.

Index properties are indicative of behavior of soil. e.g grain size distribution, relative density, Atterberg limits, etc.

Index Properties of Coarse Grained Soil:

• Grain Shape
• Grain Size
• Coarse Sieve analysis: (Dry Analysis), done for gravels with the help of 80, 20, 10 and 4.75 mm sieves.
• Fine sieve analysis: (Wet analysis) done for sand with the help of 2mm, 1mm, 600$\mu$, 425$\mu$, 212$\mu$, 150$\mu$ and 75$\mu$,
• Relative Density: Soil is classified into five types, Very loose, loose, medium dense, dense and very dense.

Index Properties of Fine Grained Soil:

• Consistency: The relative ease with which soil can be deformed. It is classified intoSolid stage, semi-solid stage, plastic stage and liquid stage.
• Atterberg's Limits
• Liquid Limit: The water content at which the behavior of a clayey soil changes from the plastic state to the liquid state.
• Plastic Limit: The plastic limit is defined as the gravimetric moisture content where the thread breaks apart at a diameter of 3.2 mm (about 1/8 inch).
• Shrinkage Limit: The moisture content at which a fine-grained soil no longer changes volume upon drying

Solved Example: 9073-01

A soil has a discharge velocity of 6 $\times$ 10$^{-7}$ m/s and a void ratio of 0.5. What is its seepage velocity?

A. 3 $\times$ $10^{-7}$ m/s

B. 6 $\times$ $10^{-7}$ m/s

C. 12 $\times$ $10^{-7}$ m/s

D. 18 $\times$ $10^{-7}$ m/s

Porosity, \begin{align*} n &= \dfrac{e}{1 + e}\\ &= \dfrac{0.5}{1 + 0.5} = \dfrac{1}{3} \end{align*} Seepage velocity, \begin{align*} v_s &= \dfrac{v}{n}\\ &= \dfrac{6 \times 10^{-7}}{\left(\dfrac{1}{3}\right)} = 18 \times 10^{-7}\ \mathrm{m/s} \end{align*}

Correct Answer: D

Solved Example: 9073-02

A tracer takes 100 days to travel from Well-1 to Well-2 which are 100 m apart. The elevation of water surface in Well-2 is 3 m below that in Well-1. Assuming porosity equal to 15%, the coefficient of permeability (expressed in m/day) is:

A. 0.30

B. 0.45

C. 1.00

D. 5.00

Correct Answer: D

Solved Example: 9073-03

A value of toughness index less than unity indicates that the soil is friable at the ______:

A. Plastic limit

B. Liquidity limit

C. Composite limit

D. Elastic limit

Correct Answer: A

Solved Example: 9073-04

The void ratio of a given soil A is twice that of another soil B, while the effective size of Particles of soil A is one-third of that of soil B. The ratio of height of capillary rise of water in soil A to that B will be:

A. 0.67

B. 1.0

C. 1.5

D. 2.0

Correct Answer: C

Solved Example: 9073-14

The maximum water content at which a reduction in water content will not cause a decrease in the volume of soil mass is called:

A. Plastic Limit

B. Shrinkage Limit

C. Plasticity

D. Liquid Limit

Correct Answer: B

Learning Objectives:

• Fundamental Principles: Understand the fundamental principles of soil classification and its importance in civil engineering projects.
• Soil Properties: Identify and explain the key physical and engineering properties of soils, including grain size distribution, consistency, permeability, and compressibility.
• Classification Systems: Familiarize yourself with common soil classification systems, such as the Unified Soil Classification System (USCS) and the American Association of State Highway and Transportation Officials (AASHTO) system.
• Particle Size Analysis: Learn the procedures for conducting particle size analysis tests, including sieve analysis and hydrometer analysis, to determine the soil's grain size distribution.
• Plasticity and Consistency: Understand the concepts of plasticity and consistency of soils and how they relate to soil classification using Atterberg limits.

Solved Example: 9074-01

Which one of the following is the correct assumption of Rankine's theory?

A. The soil mass is infinite

B. The soil mass is non homogeneous

C. The soil mass is cohesive

D. The ground surface is a plane which may be horizontal or inclined.

Correct Answer: D

Solved Example: 9074-02

The soils which plot above the A line in a plasticity chart are known as:

A. Clays

B. Sands

C. Silts

D. Organic soils

Correct Answer: A

Solved Example: 9074-03

The graphical method for the determination of earth pressure is:

A. Rebhann's method

B. Taylor's method

C. Mohr's diagram method

D. New mark's influence chart method

Correct Answer: A

Solved Example: 9074-10

Which of the following soil is least permeable?

A. Gravels

B. Silt

C. Stiff Clay

D. Sand

Correct Answer: C

Solved Example: 9074-11

Silt is the:

A. Non-cohesive soils

B. Cohesive soils

C. Gravel

D. Aggregate

Correct Answer: B