SOIL COMPACTION BASICS

Transcription

1 SOIL COMPACTION BASICS Figure courtesy of : A Basic Handbook by MultiQuip. : Densification of soil by the removal of air. Courtesy of Slide 1 of 38

2 WHY COMPACT SOILS? Figure courtesy of : A Basic Handbook by MultiQuip. Slide 2 of 38

3 MOIST UNIT WEIGHT (γ) VS. MOISTURE CONTENT (w) Conceptual (Figure 4.1. Das FGE (2005)) γ = Weight (W) Volume (V) Silty Clay (LL=37, PI =14) Example (from Johnson and Sallberg 1960, taken from TRB State of the Art Report 8, 1990) Slide 3 of 38

4 LABORATORY COMPACTION TESTS (i.e. PROCTORS) Ejector Standard Hammer 6 inch Mold Soil Plug Scale Modified Hammer 4 inch Mold Soil Plug Typical Proctor Test Equipment (Figure courtesy of test-llc.com) Slide 4 of 38

5 LABORATORY COMPACTION TEST SUMMARY Test ASTM/ AASHTO Hammer Weight (lb) Hammer Drop (in) Compaction Effort (kip-ft/ft 3 ) Standard (SCDOT) Modified D698 T-99 D1557 T Slide 5 of 38

6 LABORATORY COMPACTION TEST SUMMARY Test STANDARD ASTM D698/AASHTO T-99 MODIFIED ASTM D1557/AASHTO T-180 Method A B C A B C Material 20% Retained by #4 Sieve >20% Retained on #4 20% Retained by 3/8 in Sieve >20% Retained on 3/8 in < 30% Retained by 3/4 in Sieve 20% Retained by #4 Sieve >20% Retained on #4 20% Retained by 3/8 in Sieve >20% Retained on 3/8 in < 30% Retained by 3/4 in Sieve Use Soil Passing Sieve #4 3/8 in ¾ in #4 3/8 in ¾ in Mold Dia. (in) No. of Layers No. Blows/Layer Slide 6 of 38

7 LABORATORY COMPACTION TEST SUMMARY Figure courtesy of : A Basic Handbook by MultiQuip. Slide 7 of 38

8 LABORATORY COMPACTION TESTS (i.e. PROCTORS) Automated Proctor Equipment (Figure courtesy of Humboldt) Manual Proctor Test ( What you WILL be doing ) (Figure courtesy of westest.net) Slide 8 of 38

9 Maximum Dry Density MDD or γ d,max = pcf SP-SM % Fines = 6% Zero Air Voids (ZAV) Line G s = 2.6 From Soil Composition notes: γ γ = d 1 + w Optimum Moisture Content OMC = 11.5% Slide 9 of 38

10 ZERO AIR VOIDS LINE Dry Unit Weight (γ d ) (i.e. no water): γ d = Weight of Solids (W s ) Volume (V) = γ 1+ w γ zav = Zero Air Void Unit Weight: γ zav = G γ s 1+ e w = Gγ s w 1+ wg s = γ w + w 1 G s Slide 10 of 38

11 FACTORS AFFECTING SOIL 1. Soil Type COMPACTION Grain Size Distribution Shape of Soil Grains Specific Gravity of Soil Solids 2. Effect of Compaction Effort More Energy Greater Compaction Slide 11 of 38

12 TYPES OF COMPACTION CURVES Dry Unit Weight γ d after Figure 4.5. Das FGE (2005) C B A D Moisture Content w Lee and Suedkamp (1972) A. Single Peak (Most Soils) B. 1 ½ Peak Cohesive Soils LL<30 C. Double Peak Cohesive Soils LL<30 or Cohesive Soils LL>70 D. No Definitive Peak Uncommon Cohesive Soils LL>70 Slide 12 of 38

13 EFFECT OF SOIL MECHANICS COMPACTION ENERGY In general: Compaction Energy = γ d,max Compaction Energy = OMC Figure 4.6. Das FGE (2005). Slide 13 of 38

14 EFFECT OF COMPACTION ON COHESIVE SOILS Dry Side Wet Side Dry Side Particle Structure Flocculent OMC Wet Side Particle Structure Dispersed Figure Das FGE (2005). Slide 14 of 38

15 Hydraulic Conductivity (k): Measure of how water flows through soils In General: EFFECT OF COMPACTION ON COHESIVE SOILS Increasing w = Decreasing k Until ~ OMC, then increasing w has no significant affect on k Figure Das FGE (2005). Slide 15 of 38

16 Unconfined Compression Strength (q u ) : Measure of soil strength In General: EFFECT OF COMPACTION ON COHESIVE SOILS Increasing w = Decreasing q u SOIL MECHANICS Related to soil structure: Dry side Flocculent Wet Side Dispersed Figure Das FGE (2005). Slide 16 of 38

17 FIELD COMPACTION EQUIPMENT 4 Common Types: 1. Smooth Drum Roller 2. Pneumatic Rubber Tired Roller 3. Sheepsfoot Roller (Tamping Foot) 4. Vibratory Roller (can be 1-3) Smooth Drum Pneumatic Rubber Tired Sheepsfoot Vibratory Drum Slide 17 of 38

18 FIELD COMPACTION EQUIPMENT Photographs courtesy of: myconstructionphotos.smugmug.com /boulanger/ Holtz and Kovacs (1981) Slide 18 of 38

19 FIELD COMPACTION EQUIPMENT Fine Grained Soils Coarse Grained Soils Coarse Grained Soils Slide 19 of 38

20 FIELD COMPACTION EQUIPMENT from Holtz and Kovacs (1981) Slide 20 of 38

21 FIELD COMPACTION TESTING Relative Compaction (R or C.R.): R(%) = γ γ d ( field ) d,max Common Field Test Methods: 1. Sand Cone (ASTM D1556) 2. Rubber Balloon Method (D2167) 3. Nuclear Density (ASTM D2922) 4. Time Domain Reflectometry (D6780) 5. Shelby Tube (not commonly used) Slide 21 of 38

22 FIELD COMPACTION TESTING METHOD SAND CONE (ASTM D1556) BALLOON (ASTM D2167) NUCLEAR (ASTM D2922 & ASTM D3017) TDR (ASTM D6780) Advantages Large Sample Accurate Large Sample Direct Reading Obtained Open graded material Fast Easy to re-perform More Tests Fast Easy to re-perform More Tests Disadvantages Time consuming Large area required Slow Balloon breakage Awkward No sample Radiation Moisture suspect Under research Errors Void under plate Sand bulking Sand compacted Soil pumping Surface not level Soil pumping Void under plate Miscalibration Rocks in path Surface prep req. Backscatter Under Research after : A Basic Handbook by MultiQuip. Photographs courtesy of Durham Geo/Slope Indicator and myconstructionphotos.smugmug.com. Slide 22 of 38

23 FIELD COMPACTION TESTING Balloon Method (D ) Figure12 Sand Cone Method (D ) Figure13 Nuclear Method (D & D ) Figures courtesy of : A Basic Handbook by MultiQuip and TRB State of the Art Report 8, Slide 23 of 38

24 FIELD COMPACTION: TEST FREQUENCY Reference City of Lynchburg SCDOT QC SCDOT QA USBR Earth Manual NAVFAC DM7.02 FM Year Roads 1 per lift per 300 LF 1 per lift per 500 LF 1 per lift per 2500 LF 1 per lift per 250 LF Buildings or Structures 1 per lift per 5000 SF Airfields 1 per lift per 250 LF Embankment Mass Earthwork 1 per lift per 500 LF 1 per lift per 2500 LF 2000 CY 500 CY Canal/Reservoir Linings 1000 CY 500-1,000 CY Trenches & Around Structures 1 per lift per 300 LF 200 CY CY 1 per lift per 50 LF Parking Areas 1 per lift per SF 1 per lift per 250 SY Misc. 1 per areas of doubtful compaction 1 per areas of doubtful compaction Slide 24 of 38

25 FIELD COMPACTION: LIFT HEIGHTS State DOTs Maryland, Massachusetts, Montana, North Dakota, Ohio, Oklahoma Connecticut, Kentucky Alabama, Arizona, California, Delaware, Florida, Idaho, Illinois, Indiana, Iowa, Kansas, Maine, Minnesota, Mississippi, Missouri, Oregon, South Carolina, South Dakota, Vermont, Virginia, Washington, Wisconsin Louisiana, New Hampshire, New Jersey, Texas, Wyoming New York Maximum Lift Height Max m (6 in) lift before compaction Max m (6 in) lift after compaction Max. 0.2 m (8 in) lift before compaction Max. 0.3 m (12 in) lift before compaction Depends on Soil & Compaction Equipment After Hoppe (1999), Lenke (2006), and Kim et al. (2009). Slide 25 of 38

26 FIELD COMPACTION: ONE POINT PROCTOR SC-T-29: Standard Method of Test for Field Determination of Maximum Dry Density and Optimum Moisture Content of Soils by the One-Point Method General Procedure: Family of Curves Run one (1) Proctor Test DRY of OMC. Plot Test on Family of Curves Match to a specific curve: Take MDD and OMC Values from Table. Slide 26 of 38

27 COMPACTION CHARACTERISTICS & RATINGS: USCS SOILS USCS Sym. Compaction Equipment γ d,max D698 (lb/ft 3 ) Compression & Expansion Evaluation for Use as Fill Embankment Subgrade Base Course GW Rubber Tired Smooth Drum Vibratory Roller Almost None Very Stable Excellent Good GP Rubber Tired Smooth Drum Vibratory Roller Almost None Reasonably Stable Excellent to Good Poor to Fair GM Rubber Tired Sheepsfoot Slight Reasonably Stable Excellent to Good Fair to Poor GC Rubber Tired Sheepsfoot Slight Reasonably Stable Good Good to Fair after U.S. Army Engineer Waterways Experiment Station (now ERDC). (1960). The Unified Soil Classification System, Technical Memorandum No , Vicksburg, MS. Slide 27 of 38

28 COMPACTION CHARACTERISTICS & RATINGS: USCS SOILS USCS Sym. Compaction Equipment γ d,max D698 (lb/ft 3 ) Compression & Expansion Evaluation for Use as Fill Embankment Subgrade Base Course SW Rubber Tired Vibratory Roller Almost None Very Stable Good Fair to Poor SP Rubber Tired Vibratory Roller Almost None Reasonable stable when dense Good to Fair Poor SM Rubber Tired Sheepsfoot Slight Reasonable stable when dense Good to Fair Poor SC Rubber Tired Sheepsfoot Slight to Medium Reasonable stable Good to Fair Fair to Poor after U.S. Army Engineer Waterways Experiment Station (now ERDC). (1960). The Unified Soil Classification System, Technical Memorandum No , Vicksburg, MS. Slide 28 of 38

29 COMPACTION CHARACTERISTICS & RATINGS: USCS SOILS USCS Sym. Compaction Equipment γ d,max D698 (lb/ft 3 ) Compression & Expansion Evaluation for Use as Fill Embankment Subgrade Base Course ML Rubber Tired Sheepsfoot Slight to Medium Poor Stability Fair to Poor Not Suitable CL Sheepsfoot Rubber Tired Medium Good Stability Fair to Poor Not Suitable MH Sheepsfoot Rubber Tired High Poor Stability Should not be used Poor Not Suitable CH Sheepsfoot Very high Fair Stability Poor to Very Poor Not Suitable after U.S. Army Engineer Waterways Experiment Station (now ERDC). (1960). The Unified Soil Classification System, Technical Memorandum No , Vicksburg, MS. Slide 29 of 38

30 DYNAMIC COMPACTION Figure courtesy of Figure 1. FHWA-SA US44 Expansion Carver, MA. Slide 30 of 38

31 DYNAMIC COMPACTION after Figure 5 (FHWA-SA ). Slide 31 of 38

32 DYNAMIC COMPACTION: US 44 Slide 32 of 38

33 DYNAMIC COMPACTION: US 44 (from Hajduk et al., 2004) Slide 33 of 38

34 DYNAMIC COMPACTION: US 44 (from Hajduk et al., 2004) Slide 34 of 38

35 VIBROFLOTATION Photograph courtesy of Figure Das FGE (2005) (after Brown, 1977). Slide 35 of 38

36 VIBROFLOTATION Figure Das FGE (2005) (after Brown, 1977). Slide 36 of 38

37 VIBROFLOTATION PROBE SPACING Figure Das FGE (2005). VIBROFLOTATION EFFECTIVE GRAIN SIZE DISTRIBUTIONS Figure Das FGE (2005). Slide 37 of 38

38 COMPACTION: ASSOCIATED COSTS Figure courtesy of Slide 38 of 38