United States Department of Agriculture Engineering Field Soil Conservation Sewice Manual Chapter 4. Elementarv Soil Use bookmarks and buttons to navigate Contents Page Page Classifying Coarse-Grained Soils ..............................4-10 Soils with less than 5 percent fines .......................4-10 @ Basic Concepts .......................................................... 4-2 Soils with 12 to 50 percent fines ...........................4-11 Soil ...............................................................................4-2 Soils with 5 to 12 percent fines .............................4-11 Soil Solids ....................................................................4-2 Summary ...................................................................4-13 Soil Voids .....................................................................4-2 Origin ...........................................................................4-2 @ Field Identification and Description of Soils ..............4-19 Structure .................................................................... 4-2 Dual and Borderline Classes ................................ 4-19 Soil Water ....................................................................4-3 Apparatus needed for the tests .............................4-19 Volume-Weight Relationships...................................... 4-3 Sample size ..........................................................4-19 Void ratio .................................................................4-4 Field classification .....................................................4-19 Porosity ...................................................................4-4 Highly organic soil ................................................ 4-19 Degree of saturation ...............................................4-4 Percentages of sand. gravel. and fines .................4-19 Water Content ..............................................................4-4 Classifying fine-grained soils ..................................... 4-20 Specific gravity ........................................................4-4 Dilatancy ...............................................................4-20 Unit weight and density ........................................... 4-4 Toughness ............................................................4-20 Atterberg Limits ........................ .. ............................... 4-6 Dry strength ........................... .............................. 4-20 Shrinkage limit (SLI ................................................. 4-6 Estimating liquid limit ............................................4-21 1 Plastic limit (PL) ......................................................4-6 Modifiers for sand and gravel ................................4-21 D Liquid limit (LL) ........................................................ 4-6 Classifying coarse-grained soils ................................4-21 Plasticity index (PI) ................................................. 4-6 Soil description .......................................................... 4-23 Nonplastic (NP) ................... ........... ..................4-6 Numbering test holes and samples ....................... 4-25 Maximum particle size .......................................... 4-25 @ me unified soil classification system ......................... 4-8 Percentages of cobbles and boulders ................... 4-25 Classification Using Laboratory Data ........................... 4-8 Particle-size range of coarse materials .................4-25 Names and Symbols .................................................... 4-8 Particle angularity ................................................. 4-25 Coarse-grained soils .........................................4-8 Particle shape ....................................................4-25 Fine-grained soils ................................................4-8 Plasticity of fines ...................................................4-25 Highly organic soils ................................................4-8 Color .................................................................... 4-27 Sieve Sizes .............................................................4-8 Natural water content ............................................ 4-27 The Plasticity Chart ................... ... ...........................4-8 Reaction with HCI ............................................... 4-27 Classifying Fine-Grained Soils ...................................4-1 0 Consistency .......................................................... 4-27 Clay or silt ........................................................... 4-10 Structure ........................................................... 4-27 High or low liquid limit ......................................... 4-10 Cementation .................................................4-27 Fine-grained soils with sand andlor gravel ...........4-1 0 Site investigation ...................................................4-27 Organic soils .......................... .. ......................... 4-1 0 Preliminary data .............................................. 4-28 Summary of fine-grained soils .............................. 4-1 0 Boring program ............................................... 4-28 Ground water ........................................................ 4-28 Page Page @ Estimation of Soil Performance and Performance 4-8 Relationship between particle size and the Requirements ...............................................................4-29 USDA textural soil classes. the Unified Soil Strength .....................................................................4-29 Classification System. and the AASHTO Permeability ...............................................................4-29 soil classes ................................................ ......... 4-18 . Compressib~lrty.......................................................... 4-30 4-9 Dilatancy, strength, and toughness tests .............. 4-22 Bearing capacity ........................................................4-30 4-1 0 Particle shapes ........................ ........................4-26 Compaction ................................................................4-30 4-1 1 Flat and elongated particles.................................. 4-26 Erosion resistance .....................................................4-31 4-12 Earth pressures against walls ...............................4-33 Earth pressures .........................................................4-32 4-13 Minimum sand or gravel section........................... 4-33 Cracking .....................................................................4-33 4-14 Unified classification and properties of soils .........4-35 Shrink-swell ...............................................................4-33 4-15 Embankment types ............................................ 4-39 Frost ...........................................................................4-34 Dispersive Clay Soils .................................................4-34 Tables Behavior characteristics of soils ............................4-34 Page 4-1 Volume-weight relationships ................................... 4-7 (@ Preliminary Embankment Design for Earth Dams ..... 4-38 4-2 Sieve designation and site of openings ................. 4-8 Scope .........................................................................4-38 4-3 Soil classification chart ...................... .... ....... 4-14 General ......................................................................4-38 4-4 Minimum sample size .......................... .. .......... 4-19 Embankment stability .................................................4-38 4-5 Classification of inorganic fine-grained soil ........... 4-21 . Required design date .................................................4-42 4-6 Classification of organic fine-grained soil .............. 4-21 Selection of embankment type ..................................4-42 4-7 Field identification by visual-manual methods ...... 4-24 4-8 Test hole numbering system ................................. 4-25 4-9 Sand and gravel sizes ........................................ 4.25 Field determination of consistency of finegrained Figures soil ....................................................................... 4-27 Page 4-1 1 Maximum lift thickness for.compaction 4-1 Types of soil structure............................................. 4-3 equipment ............................................................. 4-32 4-2 Soil volume and weight relationships...................... 4-5 4-1 2 Comparative erosion resistance of soils ............... 4-32 4-3 Atterberg limits........................................................ 4-6 4-13 Volume change potential ...................................... 4-34 4-4 Unified Soil Classification System plasticity 4-14 Working classification of soils for use as fill chart ........................................................................4-9 materials for rolled earth damage ......................... 4-43 4-5 Grain-size distribution........................................... 4-1 2 4-15 Characteristics of compacted fill materials ........... 4-44 4-6 Classification of coarse-grained soils by 4-16 Characteristics of foundation materials ................. 4-44 gradation............................................................... 4-1 3 4-17 Evaluation of site and foundation conditions ........ 4-45 4-7 General relationships between systems used 4-1 8 Selection of