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Questions and Answers
What is the primary basis for classifying soil for engineering purposes?
What is the primary basis for classifying soil for engineering purposes?
- Geographical location
- Mechanical properties (correct)
- Chemical composition
- Aesthetic appearance
Which method is used for particles larger than 0.075 mm in diameter?
Which method is used for particles larger than 0.075 mm in diameter?
- Sieve Analysis (correct)
- Wet Screening
- Hydrometer Analysis
- Particle Size Measurement
What does textural classification of soil focus on?
What does textural classification of soil focus on?
- The particle-size distribution (correct)
- The organic content of the soil
- The color of the soil
- The depth of the soil layer
Which of the following terms relates to the assessment of granular material through sieves?
Which of the following terms relates to the assessment of granular material through sieves?
Why is particle-size distribution important in soil classification?
Why is particle-size distribution important in soil classification?
Which particle size has the highest percent passing?
Which particle size has the highest percent passing?
What is the percent finer for a 20 mm particle size?
What is the percent finer for a 20 mm particle size?
Which of the following particle sizes would have the least mass retained?
Which of the following particle sizes would have the least mass retained?
What is the percent passing for the 20 mm diameter sieve?
What is the percent passing for the 20 mm diameter sieve?
What does the logarithmic scale help calculate regarding the soil?
What does the logarithmic scale help calculate regarding the soil?
Which sieve has the smallest mass retained?
Which sieve has the smallest mass retained?
What is the formula for the Uniformity Coefficient, $C_u$?
What is the formula for the Uniformity Coefficient, $C_u$?
What does the effective size, $D_{10}$, indicate about granular soil?
What does the effective size, $D_{10}$, indicate about granular soil?
Which of the following is required to calculate the Coefficient of Curvature, $C_c$?
Which of the following is required to calculate the Coefficient of Curvature, $C_c$?
What is the total mass recorded in the particle-size distribution table?
What is the total mass recorded in the particle-size distribution table?
Which diameter has a percent passing of 6.02%?
Which diameter has a percent passing of 6.02%?
Which sieve retains the largest mass in the dataset?
Which sieve retains the largest mass in the dataset?
What is the significance of the Suitability Number, SN?
What is the significance of the Suitability Number, SN?
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Study Notes
Particle-Size Distribution and Sieve Analysis
- Sieve analysis determines the particle-size distribution of granular materials using a series of sieves.
- Results display diameter, mass retained, cumulative mass retained, and percent passing for each sieve.
- Effective sizes such as D10, D30, D60, and D75 are crucial for assessing soil properties like hydraulic conductivity and drainage.
Key Measurements from Data
- D10 (Effective Size) = 0.163 mm; represents the diameter for which 10% of the material is finer.
- D30 = 0.219 mm; diameter where 30% of the material is finer.
- D60 = 0.506 mm; diameter where 60% of the material is finer.
- D75 = 0.927 mm; diameter where 75% of the material is finer.
- Uniformity Coefficient (Cu) = D60/D10, reflecting soil gradation and consistency.
Soil Classification
- Soil is classified based on mechanical properties like permeability, stiffness, and strength.
- Particles are categorized into gravel, sand, silt, and clay based on size distribution.
Classification Methods
- Textural classification involves analysis of particle sizes and distributions.
- Two main analysis methods:
- Sieve Analysis for particles > 0.075 mm.
- Hydrometer Analysis for particles < 0.075 mm.
Summary of Soil Classification
- Grain size influences soil behavior.
- A well-graded soil typically has a higher uniformity coefficient indicating a mix of particle sizes contributing to stability.
Calculation of Sorting Coefficient
- Sorting Coefficient (So) = D75/D25, indicating the distribution uniformity of grain sizes.
Coefficient of Curvature
- Coefficient of Curvature (Cc) = (D30)^2 / (D60 * D10), showing the gradation of the soil.
Practical Implications
- Understanding particle-size distribution helps predict soil behavior under various conditions.
- This information is essential for civil engineering, geotechnical investigations, and construction projects.
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