CIVE.5370 EXPERIMENTAL SOIL MECHANICS Soil Sampling, Testing, & Classification Review

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1 DATA COLLECTION, INTERPRETATION, & ANALYSIS TO GEOTECHNICAL SOLUTIONS FLOW CHART PRIOR INFORMATION Reconnaissance Topography Geology Hydrology Environment SITE EXPLORATION Geophysics Drilling and Coring Sampling In-situ Testing LABORATORY TESTING Index Properties Strength Stiffness/Compressibility Flow/Permeability THEORETICAL EVALUATIONS Constitutive Models Numerical Simulation Analytical Solutions INTERPRETED SOIL PARAMETERS Geostatic Stress State Strength: Drained & Undrained Cases Stiffness & Rate Effects Anisotropy, Dynamic Response, Rheology PRIOR EXPERIENCE Statistical Trends Empirical Correlations ANALYTICAL METHODS Elastic Theory Theorem of Plasticity Limit Equilibrium COLOR CODE: Blue: CIVE.3300 & CIVE.3330 Red: CIVE.4310 ENGINEERING ANALYSIS Judgment Hand Calculations Computer Simulations Chart Solutions Experience GEOTECHNICAL SOLUTION Safe Feasible Economical NUMERICAL METHODS Finite Elements Boundary Elements Discrete Elements Finite Difference From Paul W. Mayne, PhD, P.E., Professor, Civil Engineering, GT

2 SOIL BORINGS DETERMINATION OF SOIL STRATIGRAPHY Figure 9-1. FHWA NHI Course Subsurface Investigations

3 SOIL PROFILE (EXAMPLE) Plan View (Boring Locations) Soil Profile (Cross-Section) Figure courtesy of FHWA

4 SOIL PROFILE (EXAMPLE) Boring Location Plan Figure 45. FHWA IF

5 SOIL PROFILE (EXAMPLE) Soil Profile Figure 46. FHWA IF

6 EXAMPLE INTERPRETATION SPT Given Data Provided: - Soil Stratigraphy - USCS Classification - Groundwater Table (@ Time of Testing) - SPT N Values (No Energy Measurements) - Drilling Method (HSA) - Date Started/Ended

7 CIVE.5370 EXPERIMENTAL SOIL MECHANICS WHAT DO WE NEED FOR GEOTECHNICAL DESIGN? 1. Geostratigraphy: - Layering - Soil Types - Depth to Strata 2. Total and Effective Soil Stresses: - Soil Unit Weight ( or sat = t ) - GWT Location (u) 3. Shear Strength: - Effective Friction Angle ( ') - Effective Cohesion Intercept (c') - Unconfined Compressive Strength (q u ) - Undrained Shear Strength (S u ) 4. Stress State: - Maximum Past Pressure ( vm ). - Overconsolidation Ratio (OCR) - Coefficient of Earth Pressure at Rest (K o ) 5. Stiffness and Moduli: - Elastic Modulus (E) - Shear Modulus (G) - Poisson s Ratio (ν) - Compression Index (C c ) - Rebound Index (C R ) 6. Consistency: - Void Ratio (e) - Relative Density (D r ) 7. Flow Parameters: - Coefficient of Permeability (k) - Coefficient of Consolidation (c v, c h )

8 WHAT DO WE NEED FOR GEOTECHNICAL DESIGN Associated Laboratory Testing Standards 1. Geostratigraphy: - Classification [D422-63(2007)e2 (Withdrawn), D (2009) 1, D e1, D , D a] 2. Total and Effective Soil Stresses: - Soil Unit Weight ( ) D Moisture Content D Shear Strength: - Effective Friction Angle ( ') } - Effective Cohesion Intercept (c') D , - Undrained Shear Strength (S u ) D D Stress State: - Maximum Past Pressure ( vm ).} - Overconsolidation Ratio (OCR) - Coefficient of Earth Pressure at Rest (K o ) D

9 WHAT DO WE NEED FOR GEOTECHNICAL DESIGN Associated Laboratory Testing Standards 5. Stiffness and Moduli: - Elastic Modulus (E) - Shear Modulus (G) - Poisson s Ratio (ν) - Compression Index (C c ) - Rebound Index (C R ) 6. Consistency: - Void Ratio (e) - Relative Density (D r ) } D Flow Parameters: - Coefficient of Permeability (k) D (2006) (Withdrawn 2015), D Coefficient of Consolidation (c v, c h ) D

10 WHAT DO WE NEED FOR GEOTECHNICAL DESIGN Associated Laboratory Testing Standards Also see the following: D Terminology Relating to Soil, Rock, and Contained Fluids D Standard Test Methods for Specific Gravity of Soil Solids by Water Pycnometer D Practice for Thin-Walled Tube Sampling of Soils for Geotechnical Purposes D a Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction D Practices for Preserving and Transporting Soil Samples D Practice for X-Ray Radiography of Soil Samples

11 TESTING ACCREDITATION AGENCIES American Society of Testing and Materials Materials Testing Center AASHTO Materials Reference Laboratory

12 COEFFICIENT OF VARIATION (V) FOR GEOTECHICAL PROPERTIES AND INSITU TESTS (after Duncan, 2000) Coefficient of Variation: A measure of dispersion of a probability distribution. Often expressed as the ratio of standard deviation ( ) to the mean ( ). Measured or Interpreted Parameter V (%) Unit Weight ( ) 3 to 7 Effective Friction Angle ( ') 2 to 13 Undrained Shear Strength (S u ) 13 to 40 Undrained Shear Ratio (S u / ' vo ) 5 to 15 SPT N Value 15 to 45 Electric CPT Tip Resistance (q t ) 5 to 15 after Table 52. FHWA IF Also see Chapter 8 Applying Judgment in Selecting Soil and Rock Properties for Design (FHWA IF ).

13 Geotechnical Property SIGNIFICANT DIGITS IN GEOTECHNICAL DATA Typical Units SI US Significant Digits Effective Particle Diameter mm In 2 or 3 Significant Digits Percent Passing (gradation) % % Nearest 0.1 or whole no. Atterberg Limits % % Nearest whole number Water Content % % Nearest 0.1 Unit Weight kn/m³ lb/ft³ 3 or 4 Significant Digits Relative Density % % Nearest 0.1 Hydraulic Head cm or m in or ft 3 Significant Digits Hydraulic Conductivity m/day ft/day 2 or 3 Significant Digits ASTM D : Standard Practice for Using Significant Digits in Geotechnical Data

14 SIGNIFICANT DIGITS IN GEOTECHNICAL DATA Geotechnical Property Typical Units SI US Significant Digits Stress kpa ksf 3 Significant Digits Friction Angle Degrees Degrees Nearest 0.1 Axial Strain % % 3 Significant Digits Cohesion kpa psi 2 Significant Digits ASTM D : Standard Practice for Using Significant Digits in Geotechnical Data

15 DATA PRESENTATION FIGURE EXAMPLE (POOR) Grain Size Distribution Data Typical Excel Default Graph Series

16 DATA PRESENTATION FIGURE EXAMPLE (GOOD) GRAVEL Coarse SAND Medium Fine SILT & CLAY 100 #4 #10 #30 #40 #60 #100 #200 Percent (%) Finer by Weight % Gravel = % Retained by #4 Sieve = 3% Atterberg Limits Test Results LL=60, PL = 10 D60 = 0.45mm D30 = 0.22mm D10 = 0.08mm % Fines (i.e. % Passing #200 Sieve) = 9% 0 #4 #10 #30 #40 #60 #100 # Particle Diameter (mm)

17 SOIL CLASSIFICATION BASICS Commonly based on grain size and soil consistency. Several classification systems exist: 1. Unified Soil Classification System (USCS) (ASTM D ). 2. American Association of State Highway and Transportation Officials (AASHTO) (ASTM D ). 3. U.S. Department of Agriculture (USDA). 4. Burmister Soil Identification System. 5. Massachusetts Institute of Technology (MIT).

18 SOIL GRAIN SIZES Soil Type USCS Symbol Grain Size Range (mm) USCS AASHTO USDA MIT Gravel G 76.2 to to 2 >2 >2 Sand S 4.75 to to to to 0.06 Silt M to 0.06 to Fines < to Clay C < < < Determined by Mechanical Analysis (i.e. Sieve) and Hydrometer Analysis (ASTM D (2007) Standard Test Method for Particle-Size Analysis of Soils)

19 MECHANICAL SIEVE ANALYSIS (ASTM D422, D1140 AND AASHTO T88) #40 #10 3/8 in #200 Dry Clay (kaolin) Silt Medium-Coarse Sand Fine Gravel Medium Gravel Figure 7.1. from FHWA NHI

20 COMMONLY USED STANDARD SIEVE SIZES (ASTM E11-09e1) Sieve No. Opening (mm) Opening (in) Notes 3/4 in Gravel # # # # # # # # # # # # # Course Sand (#4 to #10) Medium Sand (#10 to #40) Fine Sand (#40 to #200) # # # Silt or Clay <#200

21 CIVE.5370 EXPERIMENTAL SOIL MECHANICS PARTICLE ANGULARITY (ROUNDNESS) Definitions (from FHWA NHI ) Angular particles are those that have been freshly broken up and are characterized by jagged projections, sharp ridges, and flat surfaces. Subangular particles are those that have been weathered to the extent that the sharper points and ridges have been worn off. Subrounded particles are those that have been weathered to a further degree than subangular particles. Rounded particles are those on which all projections have been removed, with few irregularities in shape remaining. Well rounded particles are rounded particles in which the few remaining irregularities have been removed. Mitchell (1976) Fig FHWA NHI

22 HYDROMETER ANALYSIS (ASTM D442, D1140 & AASHTO T88) Based on the principle of sedimentation of soil grains in water s w Stokes Law: v D Where: v = Velocity s = soil particle density w = water density = water viscosity D = Diameter of soil particles 18 2 ASTM D152-H hydrometer Figure 2.5. Das FGE (2005).

23 GRAIN SIZE DISTRIBUTION RESULTS Figure 5. ASTM D Figure 2.6. Das FGE (2005).

24 GRAIN SIZE DISTRIBUTION TERMS Key Particle Sizes (D = Diameter) D 60 = Diameter corresponding to 60% finer in the grain size distribution. D 30 = Diameter corresponding to 30% finer in the grain size distribution. D 10 = Diameter corresponding to 10% finer in the grain size distribution. Also known as Effective Size.

25 GRAIN SIZE DISTRIBUTION TERMS Key Coefficients (C): C u = Coefficient of Uniformity (ASTM D2487) = D 60 /D 10 C c = Coefficient of Gradation = Coefficient of Curvature (ASTM D2487) = (D 30 ) 2 /(D 60 xd 10 )

26 GRAIN SIZE DISTRIBUTION -EXAMPLE UPDATE FIGURE!

27 GRAIN SIZE DISTRIBUTION -EXAMPLE Fine-Grained Soils Coarse-Grained Soils Percent Passing (by weight) CLAY SIZE SILT SIZE SAND SIZE GRAVEL Silica Sand Piedmont Silt Plastic Kaolin mm Grain Size (mm) Figure 7.2. from FHWA NHI Notice Axis Shift!

28 GRAIN SIZE DISTRIBUTION -EXAMPLE Multiple Samples of Same Soil from one site. Percent (%) Finer by Weight SAND GRAVEL Coarse Medium Fine #4 #10 #30 #40 #60 #100 #200 SILT & CLAY 0 #4 #10 #30 #40 #60 #100 # Particle Diameter (mm)

29 GRAIN SIZE DISTRIBUTION -EXAMPLE (from Hajduk et al., 2004)

30 SOIL PLASTICITY ATTERBERG LIMITS (a.k.a. w s ) (a.k.a. w p ) (a.k.a. w L ) Plasticity Index (PI) PI = LL - PL Range of water content over which soil remains plastic. Figure 2-5. FHWA NHI

31 SOIL PLASTICITY ATTERBERG LIMITS Liquid Limit Device Plastic Limit Device Figure 24. from FHWA IF ASTM D Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. Liquid Limit (LL or w L ) Test LL and PL photographs courtesy Prof. Reddy, UIC. Plastic Limit (PL or w P ) Test

32 ATTERBERG LIMITS LIQUID LIMIT ASTM D Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. Assemble components & soil. Mix soil & water. Fill LL Device ~2/3 high with wet soil. Cut groove with tool. Mix soil with more water. Repeat. Lift LL Device with constant rate. Count number of blows to close groove ½ inch. Photographs courtesy of Engineering Properties of Soils Based on Laboratory Testing Manual, Prof. Krishna Reddy, UIC, 2002.

33 ATTERBERG LIMITS LIQUID LIMIT Run 4 Tests 2 > 25 blows 2 < 25 blows. Plot Number of Blows (N) on Log Scale. LL is N=25 (Round to 1%) Example of Liquid Limit Data Plot

34 ATTERBERG LIMITS PLASTIC LIMIT ASTM D Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. Assemble components & soil. Mix soil & water. Run 4 Tests. Average water content for 4 tests = w P = PL Roll wet soil to ellipsoidal mass with hands. Roll on PL Device until 1/8 inch diameter roll is achieved. Photographs courtesy of Engineering Properties of Soils Based on Laboratory Testing Manual, Prof. Krishna Reddy, UIC, When soil crumbles when 1/8 inch diameter is achieved, you are at PL. Take water content.

35 UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) Divided into two broad categories: Coarse Grained Soils Gravels (G) and Sands (S) < 50% passing through #200 sieve (i.e. >50% retained on #200 sieve) Fine Grained Soils Silts (M) and Clays (C) 50% passing through #200 sieve

36 CIVE.5370 EXPERIMENTAL SOIL MECHANICS UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) Uses 2 or 4 letter Group Symbols and Group Names Primary soil component first symbol 4 letter symbols either sands and gravels with 5% % Fines 12% or CL-ML on Casagrande Chart Need to know the following: Grain Size Distribution Percent Fines (i.e. particles finer than #200 sieve) Percent Sand Percent Gravel #4 and #200 sieves C c and C u from grain size analysis using D 10, D 30, D 60 Atterberg Limit Results (LL, PI)

37 UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) Example of 2 Group Symbol: SM Primary Component (Sand = S) Secondary Description (M = Silty) Primary Components G = Gravel S = Sand M = Silt C = Clay O = Organic Secondary Descriptions (Coarse Grained) M = Silty C = Clayey P = Poorly Graded (same relative grain size) W = Well Graded (different grain sizes) Secondary Descriptions (Fine Grained) L = Low Plasticity (Lean for Clay) H = High Plasticity (Fat for Clay, Elastic for Silt)

38 UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) Secondary Descriptions (Coarse Grained) M = Silty: > 12% fines, PI<4 or plots below A Line C = Clayey: > 12% fines, PI>7 and plots on or above A line P = Poorly Graded: < 5% fines, C u < 6 and/or 1>C c >3 W = Well Graded: < 5% fines, C u 6 and 1 C c 3

39 PARTICLE SIZE DISTRIBUTION CURVES Three Types of Curves: Poorly Graded (P) Gap Graded Well Graded (W) Gap Graded Figure 2-3. from FHWA NHI

40 UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) Secondary Descriptions (Fine Grained) L = Low Plasticity (Lean for Clay) (LL <50%) H = High Plasticity (Fat for Clay, Elastic for Silt) (LL 50%) (e.g. high quality pottery clay)

41 CASAGRANDE PLASTICITY CHART Figure 4. (ASTM D ).

42 CASAGRANDE PLASTICITY CHART SIGNIFICANCE OF ATTERBERG LIMITS I consider it essential that an experienced soils engineer should be able to judge the position of soils, from his territory, on a plasticity chart merely on the basis of his visual and manual examination of the soils. Arthur Casagrande (1959) Figure 2. (NAVFAC DM7.01).

43 USCS COARSE GRAINED SOILS (>50% RETAINED ON #200 SIEVE) Figure 3. ASTM D

44 USCS FINE GRAINED SOILS ( 50% PASSING #200 SIEVE) Figure 1. ASTM D

45 USCS CLASSIFICATION EXAMPLE US44 EXPANSION, CARVER, MA Table 1. Sample 1 Grain Size Results (ASTM D422). Sieve No. Dia. (mm) % Passing ½ in # Table 2. Atterberg Limits Results (ASTM D4318). Sample LL PL # # # # # # REQUIRED: Determine the USCS Soil Classification based on the provided soil index testing.

46 USCS CLASSIFICATION EXAMPLE

47 USCS CLASSIFICATION EXAMPLE

48 USCS CLASSIFICATION EXAMPLE Fines classify as MH

49 USCS CLASSIFICATION EXAMPLE 88% Sand C u = 5.63 Fines = MH 3% Gravel ANSWER: SP-SM (Poorly Graded Sand with Silt) 9% Fines Figure 3. ASTM D

50 AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO) ORIGIN (Holtz and Kovacs, 1981): This system was originally developed by Hogentogler and Terzaghi in 1929 as the Public Roads Classification System. Afterwards, there are several revisions. The present AASHTO (1978) system is primarily based on the version in STANDARDS: AASHTO M (2003) Standard Specifications for Classification of Soils and Soil-Aggregate Mixtures for Highway Construction Purposes. ASTM D Standard Practice for Classification of Soils and Soil- Aggregate Mixtures for Highway Construction Purposes.

51 AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO) Comprised of 8 Major Groups: Required Testing: A1 through A7 (with subgroups) Sieve Analysis and Atterberg Limits A8 (Organics) Subgroups determined from Group Index (GI) A1 to A3 A4 to A7 Granular Materials ( 35% passes #200 Sieve) Using LL and PI separates silty materials from clayey materials (only for A2 group) Silt-Clay Materials ( 36% passes #200 Sieve) Using LL and PI separates silty materials from clayey materials General Notes: A-1 materials are well graded, whereas A-3 soils are clean, poorly graded sands. A4 & A5 are generally silts, A6 & A7 are generally clays.

52 STEPS: CIVE.5370 EXPERIMENTAL SOIL MECHANICS AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO) 1. Determine Grain Size Distribution (AASHTO T-11 & AASHTO T-27) 2. Determine Liquid Limit (AASHTO T-89) 3. Determine Plastic Limit (AASHTO T-90) 4. Classify Soil using Table 2 ASTM 3282 (Left to Right Method, Process of Elimination)

53 AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO) Go from Left to Right, Process of Elimination Table 2 from ASTM D Standard Practice for Classification of Soils and Soil-Aggregate Mixtures for Highway Construction Purposes.

54 AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO)

55 AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO) Group Index (GI): Empirical Formula used to evaluate soils in a group (i.e. subgroup) The first term is determined by the LL GI ( LL 40) 0.01( F 15)( PI 10) ( F 35) F 200 : % Passing #200 Sieve The second term is determined by the PI For Groups A-2-6 and A-2-7 GI 0.01(F )(PI 10) use the second term only In general, the rating for a pavement subgrade is inversely proportional to the group index, GI.

56 AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO) Group Index (GI): Empirical Formula used to evaluate soils in a group (i.e. subgroup)

57 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) How does an engineer or geologist identify soils from borings, test pits, or other samples without index testing? ASTM D2488: Description and Identification of Soils (Visual Manual Procedure) Based on USCS (ASTM D2487) Apparatus: - Spatula or Pocket Knife - Small Test Tube (Optional) - Small Hand Lens (i.e. Magnifying Glass) (Optional) Courtesy of Soil Consultants Inc.

58 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 1: Obtain and Prepare Sample for Identification. Obtain sample representative of stratum via an appropriate, accepted, or standard procedure (e.g. D1452, D1587, D1586). D1452: Auger Borings D1586: SPT D1587: Undisturbed Maximum Particle Size 3in 1½in ¾in Min. Specimen Size (Dry Weight) 132 lb (60 kg) 18 lb (8 kg) 2.2 lb (1 kg) Sample retrieved from SPT Split Spoon is typically > 100 g ⅜ in 0.5 lb (200 g) #4 Sieve 0.25 lb (100 g)

59 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 2: Identify Color, Odor (if any), and Texture (coarse grained or fine grained) of Soil. See also Munsell and Humboldt (H-4368) Soil Color Charts.

60 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 3: Identify and Estimate Percentage of Major Soil Constituent. Soil Constituent Max Size Limits Min Familiar Example Boulder > 12in Basketball Cobbles 12in 3in Grapefruit Coarse Gravel 3 ¾in Oranges/Lemons Fine Gravel ¾in #4 (4.75mm) Grapes or Peas Coarse Sand #4 (4.75mm) #10 (2mm) Rock Salt Medium Sand #10 (2mm) #40 (0.42mm) Sugar, Table Salt Fine Sand #40 (0.42mm) #200 (0.075mm) Powdered Sugar Fines < #200 (0.075mm) Talcum Powder

61 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 4: Estimate Percentages of All Other Soil Constituents and Identify by the Following Terms (Estimate to nearest 5%). Term Percent by Weight Some 30% to 45% Little 15% to 25% Few 5% to 10% Trace < 5%

62 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 5A: If Major Soil Constituent is Coarse Grained (< 50% Fines). Identify Particle Distribution Well Graded: Soil consists of particle sizes over a wide range. Example: GABC Poorly Graded: Soil consists of particles which are approximately all the same size. Example: Beach Sand Well Graded Poorly Graded

63 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 5A: If Major Soil Constituent is Coarse Grained (< 50% Fines). Identify Angularity Smooth curved sides, no edges Rounded Subrounded Nearly plane sides but have well-rounded corners and edges Similar to angular but w/ rounded edges Sharp edges, relatively plane sides with unpolished surfaces Subangular Angular

64 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 5A: If Major Soil Constituent is Coarse Grained (< 50% Fines). Identify Group Symbol and Name ASTM D2488 Figure 2

65 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 5B: If Major Soil Constituent is Fine Grained ( 50% Fines). Determine Dry Strength: Mold material into minimum of three ½in diameter balls. Add water if necessary. Allow of material to dry in air, sun, or by artificial means as long as temperature does not exceed 60 C. Crush between fingers. Record dry strength as follows: Description None Low Medium High Very High Criteria Crumbles to powder with mere pressure of handling Crumbles with some finger pressure Crumbles with considerable finger pressure Cannot be broken with finger pressure. Can be broken between thumb and hard surface Cannot be broken between thumb and hard surface

66 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 5B: If Major Soil Constituent is Fine Grained ( 50% Fines). Determine Dilatancy: Mold ball of material ½in in diameter with soft but not consistency. Add water as necessary. Smooth ball into palm of hand using spatula. Shake horizontally, striking hand with soil with free hand several times. Squeeze sample by closing hand or pinching. Note reactions. Reaction is speed of which water appears while shaking and disappears while squeezing. Description None Slow Rapid Criteria No visible change in specimen Water appears slowly on surface during shaking and does not disappear/disappears slowly upon squeezing Water appears quickly on the surface of the specimen during shaking and disappears quickly upon squeezing

67 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 5B: If Major Soil Constituent is Fine Grained ( 50% Fines). Determine Toughness: Roll the samples from the dilatancy tests into a ⅛in diameter thread. Fold thread and reroll it repeatedly until the thread crumbles at a ⅛in diameter. This is the plastic limit. Knead material into lump until it crumbles. Note the pressure required roll the thread at the plastic limit and when material crumbles during kneading. Description Low Medium High Criteria Only slight pressure is required to roll the thread near the plastic limit. Thread and lump are weak and soft. Medium pressure is required to roll the thread near the plastic limit. Thread and lump have medium stiffness. Considerable pressure is required to roll the thread near the plastic limit. Thread and lump have very high stiffness.

68 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 5B: If Major Soil Constituent is Fine Grained ( 50% Fines). Identify Plasticity: Soil Symbol Dry Strength Dilatancy Toughness ML None to Low Slow to Rapid Low or Thread cannot be formed CL Medium to High None to Slow Medium MH Low to Medium None to Slow Low to Medium CH High to Very High None High

69 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 5B: If Major Soil Constituent is Fine Grained ( 50% Fines). Identify Group Name and Symbol

70 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 6: Identify Moisture Content Description Dry Moist Wet Saturated Criteria Absence of Moisture, Dusty, Dry to Touch Damp but no visible moisture Soil is clearly wet; water is visible when sample is squeezed Water is easily visible and drains freely from sample

71 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 7A: Soil Classification Checklist: 1. Group Name 2. Group Symbol 3. Percent of cobbles or boulders, or both (by volume) 4. Percent gravel, sand, or fines, or all three (by dry weight) 5. Particle size range: Gravel fine, coarse Sand fine, medium, coarse 5. Particle Angularity 6. Particle Shape (not covered in lab) 7. Maximum Particle Size or Dimension 8. Hardness of coarse sand or larger particles (not covered in lab) 9. Plasticity of fines 10.Dry Strength 11.Dilatancy 12.Toughness

72 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 7A: Soil Classification Checklist: 13.Color 14.Odor 15.Moisture 16.Reaction with HCL (not covered in lab) For intact samples (not covered in lab) 18.Consistency 19.Structure 20.Cementation 21.Local Name 22.Geologic Interpretation 23.Additional Comments Too Much Information for Typical Boring Logs EXAMPLE: Silty Sand with Gravel (SM) About 60 % predominantly fine sand; about 25 % silty fines with low plasticity, low dry strength, rapid dilatancy, and low toughness; about 15 % fine, hard, subrounded gravel, a few gravel-size particles fractured with hammer blow; maximum size, 25 mm; no reaction with HCl (Note Field sample size smaller than recommended).

73 BORING LOG EXAMPLES Courtesy of gint.com Courtesy of Soil Consultants Inc.

74 VISUAL-MANUAL SOIL CLASSIFICATION (USCS) Step 7B: Material Description for SCDOT Boring Logs: a. Relative Density/Consistency b. Moisture Condition c. Color d. Angularity e. HCl Reaction f. Cementation g. Particle-Size Range h. Primary Soil Type (all capital letters) i. USCS Soil Designation j. AASHTO Soil Designation MUNSEL Color Chart Designation LL, PL, PI NMC %#200 Sieve

75 Apparent Density (Coarse Grained) or Consistency (Fine Grained) Based on N value Relative Density (Coarse Grained) Consistency (Fine Grained) Relative Density SPT N (blows/ft) D r (%) Consistency SPT N (blows/ft) Very Loose Loose Medium Dense Dense Very Dense > Very Soft 0-2 Soft 3-4 Firm 5-8 Stiff 9-15 Very Stiff Hard > 30

76 CIVE.5370 EXPERIMENTAL SOIL MECHANICS