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Unified Soil Classification System Training

Unified Soil Classification System Training. Part B - USCS using Laboratory Data. USDA. cobbles. clay. silt. sand. gravel. 2 m. # 4. 3”. .05 mm. USCS. cobbles. fines. sand. gravel. # 4. 3”. .074 mm. Comparison of Particle Size Definitions. # 200. ASTM Standards .

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Unified Soil Classification System Training

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  1. Unified Soil Classification System Training Part B - USCS using Laboratory Data

  2. USDA cobbles clay silt sand gravel 2 m # 4 3” .05 mm USCS cobbles fines sand gravel # 4 3” .074 mm Comparison of Particle Size Definitions # 200

  3. ASTM Standards • Lab Data Classification is byASTM D2487 • Classification of Peat Samples, see ASTM D 4427 • Field Classification is by D2488

  4. Comparison of Particle Size Definitions

  5. Activity 2 - Particle Size Comparisons

  6. USCS Flow Chart - Activity 3

  7. Flow Chart Overview • Two Broad Categories • Fine-Grained - 50% or more finer than the # 200 sieve • Coarse-Grained - Less than 50% finer than the # 200 sieve

  8. USCS Overview

  9. Flow Chart Overview • Fine-Grained Soils • Organic ( LL ratio < 0.75 ) • Inorganic (no odor and LL ratio not < 0.75) • Classify by LL, PI • Modifiers are H or L for LL value, C or M for plasticity and O for organic

  10. USCS Overview

  11. Activity 4 - Organic Soil Solve 4 samples

  12. Abbreviations Fine-Grained • H - High LL ( > 50 ) • L - Low LL ( < 50 ) • C - Plastic Fines • M - Nonplastic or slightly plastic fines • O - Organic • Pt - Peat

  13. Activity 5 - Plasticity Chart

  14. Activity 5 - Plasticity Chart Solve 4 samples

  15. Activity 7 - Classify Fine-Grained Samples Assume 6 samples are not organic and classify by USCS

  16. Flow Chart Overview • Coarse-Grained Soils - 3 Groups • Clean - Less than 5 % Fines • Dirty - More than 12 % Fines • Dual - From 5% to 12% Fines, inclusive

  17. Coarse-grained Soils

  18. Abbreviations Sands and Gravels • G - Gravel • S - Sand • P - Poorly Graded • W - Well Graded

  19. % gravel = % finer 3”minus % finer # 4 % sand = % finer # 4 minus % finer # 200 % fines = % finer than # 200 sieve Sieve Analyses

  20. Percent Particle Categories • To compute % Gravel subtract % finer than # 4 from % finer than 3” • To compute % Sand subtract % finer than # 200 from % finer than # 4 • Percent Fines is % finer than # 200

  21. Activity 8 For 7 samples, fill out Activity

  22. Additional Definitions • To Classify Clean Coarse-Grained Soils, you must first plot grain-size curve and determine three parameters D10, D30, D60

  23. Determining D10, D30, and D60 60 % finer D60, millimeters 30 10 D30, millimeters D10, millimeters

  24. Computing CU and CC Coefficient of Uniformity High Values Indicate Well-Graded Soil Coefficient of Curvature Values Between 1-3 Indicate Well-Graded Soil

  25. Activity 9 Plot Curve from Data, compute CU Value

  26. Activity 10 Plot Curve from Data, compute CC Value

  27. Well graded Characterizing Clean Sands and Gravels Clean Well Graded Sands and Gravels have less than 5 % fines and a wide range of particle sizes that are equally distributed % Finer Particle Size

  28. Either Mostly One-Size Particle Or Gap- Graded % Finer % Finer Poorly graded Gap graded Particle Size Particle Size Poorly GradedSands and Gravels

  29. Sands less than 5 % fines CU > 6 CC = 1-3 Gravels less than 5 % fines CU > 4 CC = 1-3 Clean, Well/Poorly Graded Definitions

  30. Activity 11 - Problems 1. Verify % Fines - Coarse-Grained/Clean 2. Compute % Gravel and % Sand 3. Note which predominates 4. Using provided CU and CC, Determine whether poorly or well graded 5. Determine Correct USCS classification

  31. Activity 12 Review Example Soil

  32. Activity 13 Use Flow Chart, Classify Soil

  33. Activity 14 Summary of Classifications of Coarse-Grained Soils • Clean Sands and Gravels (< 5% fines) • Clean Poorly Graded Gravels GP • Clean Well Graded Gravels GW • Clean Poorly Graded Sands SP • Clean Well Graded Sands SW

  34. Dirty Coarse-Grained Soils • If a sample has less than 50 % Fines • And it has more than 12 % Fines, it is a Dirty Coarse-Grained Soil • To Classify, follow the flow chart and the following steps

  35. Dirty Coarse-Grained Soil • Determine whether there is a greater % of Sand or Gravel • % G = % finer 3” minus # 4 • % S = % finer # 4 minus # 200 • Determine where minus # 40 fines plot on plasticity chart

  36. Sands Gravels Dirty Sands and Gravels • SC - Fines Plot Above A-Line • SM - Fines Plot Below A-Line • SC-SM - Fines Plot in Hatched Zone • GC - Fines Plot Above A-Line • GM - Fines Plot Below A-Line • GC-GM - Fines Plot in Hatched Zone

  37. Activity 16 - Problems

  38. Activity 17 - Example of Classifying Dual-Classification Coarse-Grained Soil

  39. Activity 18 - Problem

  40. Activity 20 - Review Questions

  41. Activity 21 - Comprehensive Problems

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