14.330 Soil Compaction

14.330 SOIL MECHANICS Soil Compaction

SOIL COMPACTION BASICS

Figure courtesy of Soil Compaction: A Basic Handbook by MultiQuip.

Soil Compaction: Densification of soil by the removal of air. Courtesy of http://www.extension.umn.edu Revised 02/2013

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WHY COMPACT SOILS?

Revised 02/2013

Figure courtesy of Soil Compaction: A Basic Handbook by MultiQuip.

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MOIST UNIT WEIGHT () VS. MOISTURE CONTENT (w)

Conceptual (Figure 4.1. Das FGE (2005))

Revised 02/2013

Weight (W) γ Volume (V)

Silty Clay (LL=37, PI =14) Example (from Johnson and Sallberg 1960, taken from TRB State of the Art Report 8, 1990)

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LABORATORY COMPACTION TESTS (i.e. PROCTORS) Standard Hammer Ejector

Soil Plug 6 inch Mold

Scale

Modified Hammer

4 inch Mold

Soil Plug

Typical Proctor Test Equipment Revised 02/2013

(Figure courtesy of test-llc.com)

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LABORATORY COMPACTION TEST SUMMARY Test

Hammer Hammer Compaction ASTM/ Drop Effort Weight AASHTO (kip-ft/ft3) (lb) (in)

Standard (SCDOT)

D698 T-99

5.5

12

12.4

Modified

D1557 T-180

10

18

56

Revised 02/2013

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LABORATORY COMPACTION TEST SUMMARY Test Method

STANDARD ASTM D698/AASHTO T-99 A

B

C

Material

≤ 20% Retained by #4 Sieve

>20% Retained on #4 ≤ 20% Retained by 3/8 in Sieve

Use Soil Passing Sieve

#4

Mold Dia. (in)

MODIFIED ASTM D1557/AASHTO T-180 A

B

C

>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

3/8 in

¾ in

#4

3/8 in

¾ in

4

4

6

4

4

6

No. of Layers

3

3

3

5

5

5

No. Blows/Layer

25

25

56

25

25

56

Revised 02/2013

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LABORATORY COMPACTION TEST SUMMARY

Figure courtesy of Soil Compaction: A Basic Handbook by MultiQuip. Revised 02/2013

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LABORATORY COMPACTION TESTS (i.e. PROCTORS)

Revised 02/2013

Automated Proctor Equipment

Manual Proctor Test (“What you WILL be doing”)

(Figure courtesy of Humboldt)

(Figure courtesy of westest.net)

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14.330 SOIL MECHANICS Soil Compaction SP-SM % Fines = 6% Maximum Dry Density MDD or d,max = 112.2 pcf

Zero Air Voids (ZAV) Line Gs = 2.6

From Soil Composition notes:

γ γd  1 w

Revised 02/2013

Optimum Moisture Content OMC = 11.5%

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ZERO AIR VOIDS LINE Dry Unit Weight (d) (i.e. no water):

Weight of Solids (Ws ) γ  γd  Volume (V) 1 w

zav = Zero Air Void Unit Weight:

γ zav

Revised 02/2013

w Gs  w Gs γ w    1  e 1  wGs w  1 Gs Slide 10 of 38


FACTORS AFFECTING SOIL COMPACTION 1. Soil Type Grain Size Distribution Shape of Soil Grains Specific Gravity of Soil Solids 2. Effect of Compaction Effort More Energy – Greater Compaction Revised 02/2013

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TYPES OF Lee and Suedkamp (1972) COMPACTION CURVES A. Single Peak Dry Unit Weight d

(Most Soils)

B. 1 ½ Peak Cohesive Soils LL70 Slide 12 of 38


EFFECT OF COMPACTION ENERGY

In general: Compaction Energy =

d,max

Compaction Energy =

OMC

Revised 02/2013

Figure 4.6. Das FGE (2005).

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EFFECT OF COMPACTION ON COHESIVE SOILS Dry Side

Wet Side

Dry Side Particle Structure Flocculent OMC

Revised 02/2013


Wet Side Particle Structure Dispersed

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EFFECT OF COMPACTION ON COHESIVE SOILS Hydraulic Conductivity (k): Measure of how water flows through soils In General: Increasing w = Decreasing k Until ~ OMC, then increasing w has no significant affect on k Revised 02/2013


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EFFECT OF COMPACTION ON COHESIVE SOILS Unconfined Compression Strength (qu) : Measure of soil strength In General: Increasing w = Decreasing qu Related to soil structure: Dry side – Flocculent Wet Side – Dispersed

Revised 02/2013


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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)

Pneumatic Rubber Tired Revised 02/2013

Sheepsfoot

Smooth Drum

Vibratory Drum Slide 17 of 38


FIELD COMPACTION EQUIPMENT

Photographs courtesy of: myconstructionphotos.smugmug.com http://cee.engr.ucdavis.edu/faculty /boulanger/ Holtz and Kovacs (1981) Revised 02/2013

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FIELD COMPACTION EQUIPMENT Fine Grained Soils

Course Grained Soils

Course Grained Soils Revised 02/2013

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FIELD COMPACTION EQUIPMENT

Revised 02/2013

from Holtz and Kovacs (1981)

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FIELD COMPACTION TESTING Relative Compaction (R or C.R.):

 d ( field ) R(%)  100  d ,max

5 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) Revised 02/2013

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FIELD COMPACTION TESTING SAND CONE

BALLOON

(ASTM D1556)

(ASTM D2167)

NUCLEAR

TDR

(ASTM D2922 & ASTM D3017)

(ASTM D6780)

• 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

METHOD

Advantages

Revised 02/2013

after Soil Compaction: A Basic Handbook by MultiQuip. Photographs courtesy of Durham Geo/Slope Indicator and myconstructionphotos.smugmug.com.

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FIELD COMPACTION TESTING

Balloon Method (D2167-08)

F

Sand Cone Method (D1556-07) Revised 02/2013

1 3

Nuclear Method (D2922-05 & D3017-05)

Figures courtesy of Soil Compaction: A Basic Handbook by MultiQuip and TRB State of the Art Report 8, 1990.

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FIELD COMPACTION: TEST FREQUENCY Reference

City of Lynchburg

SCDOT QC

SCDOT QA

USBR Earth Manual

NAVFAC DM7.02

FM 5-410

Year

2004

1996

1996

1998

1986

1997

Roads

1 per lift per 300 LF



Buildings or Structures

1 per lift per 5000 SF



Airfields Embankment Mass Earthwork


Canal/Reservoir Linings Trenches & Around Structures


Parking Areas

1 per lift per 10000 SF

Misc.

Revised 02/2013


2000 CY

500 CY

1000 CY

500-1,000 CY

200 CY

200-300 CY

1 per lift per 50 LF 1 per lift per 250 SY

1 per areas of doubtful compaction

1 per areas of doubtful compaction

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FIELD COMPACTION: LEFT HEIGHTS State DOTs

Maximum Lift Height

Maryland, Massachusetts, Montana, North Dakota, Ohio, Oklahoma

Max. 0.15 m (6 in) lift before compaction

Connecticut, Kentucky

Max. 0.15 m (6 in) lift after compaction

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

Depends on Soil & Compaction Equipment

Revised 02/2013

After Hoppe (1999), Lenke (2006), and Kim et al. (2009).

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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 Revised 02/2013

• 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


COMPACTION CHARACTERISTICS & RATINGS: USCS SOILS USCS Compaction Sym. Equipment

d,max D698 (lb/ft3)

Evaluation for Use as Fill Compression & Expansion

Embankment

Subgrade

Base Course

GW

Rubber Tired Smooth Drum Vibratory Roller

125 – 135

Almost None

Very Stable

Excellent

Good

GP

Rubber Tired Smooth Drum Vibratory Roller

115 – 125

Almost None

Reasonably Stable

Excellent to Good

Poor to Fair

GM

Rubber Tired Sheepsfoot

120 – 135

Slight

Reasonably Stable

GC


115 - 130

Slight

Reasonably Stable

Revised 02/2013

Excellent to Good

Good

after U.S. Army Engineer Waterways Experiment Station (now ERDC). (1960). “The Unified Soil Classification System,” Technical Memorandum No. 3-357, Vicksburg, MS.

Fair to Poor

Good to Fair

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Embankment

Subgrade

Base Course

110-130

Almost None

Very Stable

Good

Fair to Poor

100-120

Almost None

Reasonable stable when dense

Good to Fair

Poor

Good to Fair

Poor

Good to Fair

Fair to Poor

SW

Rubber Tired Vibratory Roller

SP

Rubber Tired Vibratory Roller

SM


110-125

Slight

Reasonable stable when dense

SC


105-125

Slight to Medium

Reasonable stable

Revised 02/2013


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Embankment

Subgrade

Base Course

ML


95-120

Slight to Medium

Poor Stability

Fair to Poor

Not Suitable

CL

Sheepsfoot Rubber Tired

95-120

Medium

Good Stability

Fair to Poor

Not Suitable

MH

Sheepsfoot Rubber Tired

70-95

High

Poor Stability Should not be used

Poor

Not Suitable

CH

Sheepsfoot

80-105

Very high

Fair Stability

Poor to Very Poor

Not Suitable

Revised 02/2013


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DYNAMIC COMPACTION

Figure courtesy of www.betterground.com

Figure 1. FHWA-SA-95-037. Revised 02/2013

US44 Expansion Carver, MA.

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DYNAMIC COMPACTION

Revised 02/2013

after Figure 5 (FHWA-SA-95-037).

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DYNAMIC COMPACTION: US 44

Revised 02/2013

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Revised 02/2013

(from Hajduk et al., 2004)

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Revised 02/2013

(from Hajduk et al., 2004)

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VIBROFLOTATION

Photograph courtesy of http://www.vibroflotation.com

Figure 4.18. Das FGE (2005) (after Brown, 1977). Revised 02/2013

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VIBROFLOTATION

Figure 4.19. Das FGE (2005) (after Brown, 1977). Revised 02/2013

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VIBROFLOTATION PROBE SPACING


VIBROFLOTATION EFFECTIVE GRAIN SIZE DISTRIBUTIONS Revised 02/2013


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COMPACTION: ASSOCIATED COSTS

Revised 02/2013

Figure courtesy of www.groundimprovement.ch.

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