Full Text

i

Joint

Transportation

Research

Program

JTRP

FHWA/IN/JTRP-99/4

Final

Report

EMBANKMENT

WIDENING

DESIGN GUIDELINES

AND

CONSTRUCTION PROCEDURES

Richard

J.

Deschamps

Christopher

S.

Hynes

Philippe

Bourdeau

September

1999

Indiana

Department

of

Transportation

Purdue

University

TECHNICALREPORTSTANDARDTITLEPAGE

1. Report No.

FHWA/IN/JTRP-99/4

2. GovernmentAccessionNo. 3.Recipient'sCatalogNo.

4.TitleandSubtitle

EmbankmentWidening DesignGuidelinesandConstructionProcedures

5.Report Date

September 1999

6. Performing OrganizationCode

7.AuthorO)

RichardJ.Deschamps,ChristopherS.Hynes,andPhilippeBourdeau

8. Performing OrganizationReport No.

FHWA/IN/JTRP-99/4

9.Performing OrganizationNameandAddress

JointTransportationResearch Program

1284CivilEngineering Building

PurdueUniversity

WestLafayette,Indiana 47907-1284

10.WorkUnit No.

11. ContractorGrant No.

SPR-2039

12. SponsoringAgencyNameandAddress

IndianaDepartment ofTransportation

StateOfficeBuilding

100NorthSenateAvenue

Indianapolis,IN 46204

13. TypeofReportand Period Covered

FinalReport

14. SponsoringAgencyCode

15. Supplementary Notes

Preparedincooperation with the IndianaDepartment ofTransportationandFederalHighwayAdministration.

16. Abstract

InrecentyearsfailureshaveoccurredinIndianahighwayembankmentswheretheembankmentswere widened andsteepenedin

order tofacilitateconstructionoflonger, saferaccelerationanddecelerationlanesandto increase thetrafficcapacityandefficiencyofexisting

thoroughfares. Theobjectivesofthisstudywereto investigate thecauseoffailureandtomakerecommendationsformodifyingthe existing

INDOT

StandardSpecificationsandconstruction guidelinesinanattempttoavoidsimilarfailures inthefuture.

A

literaturereviewandsurveyofstateandfederal transportationagencieswasperformedto collect current, availabledesign

guidelinesandconstructionproceduresfor sideslopesteepeningprojects. Severalprojectswereinvestigatedwhere widening andsteepeningof

existingembankments wasperformed. Bothfailedandsuccessful projectswereinvestigatedtodiscernthe differencesinapproach usedthat

mayhaveled to failure insomecases. Foreachsite,availabledesigndocuments andconstructionrecordswerereviewedtoidentifykeyaspects

ofindividual projects thatmayhavecontributed totheprojectsbeing categorizedas successfulorunsuccessful. In general,verylittle

informationwasavailable intermsof engineering design documents,fieldobservationsduringconstruction,or as-builtdrawingsforthese

projects. Forthemostpart quality controltestswerelimited totheright-of-way withfewtestsconductedinthewidenedslopes.

Investigationsofthefailedembankmentsinvolved bothfieldinvestigationsandlaboratorytests,includingSPTand

CPT

tests,test

pits,in situdensitytests,indextests,compactiontests,andstrengthtests. Investigationsofsuccessful projectswerealsoperformedand

includedsitereconnaissanceandhandaugerborings.

Theresultsoftheinvestigations indicate thatfailureof thewidenedembankmentsresultedfromsub-standardcompactionoffilland

inadequatebenchingintothe originalembankment. Surface waterinfiltrationfromtheroadwayrun-offcontributed totheproblem,possibly

saturatingandsofteningthesoils. It isconcludedthattheslopefailuresinvestigatedwouldnothaveoccurredif

INDOT

Standard

Specificationswerefollowed duringconstruction. Therefore,itappearsthattheprimary causeoffailureisthe lackofappreciationofthe

potentialriskbythepartiesinvolved. Severalrecommendationsare providedtohelp preventthesetypesoffailureinthe future, including

modificationsto the existing specificationsandthe transferof informationamong

INDOT

personnel

17. Keywords

soils,embankments,compaction,failure,widening,

steepening,benching, curbing,compactioncontrol.

18.DistributionStatement

No

restrictions. Thisdocumentisavailable to the publicthroughthe

NationalTechnical InformationService, Springfield,

VA

22161

19. SecurityClassir.(ofthisreport)

Unclassified

20. SecurityClassif.(ofthispage) Unclassified

21.No.ofPages

67

Digitized

by

the

Internet

Archive

in

2011

with

funding

from

LYRASIS

members

and

Sloan

Foundation; Indiana

Department

of

Transportation

TABLE OF

CONTENTS

Page

TABLE OF

CONTENTS

i

LIST

OF

TABLES

iv

LIST

OF

FIGURES

v

LIST

OF SYMBOLS

vii

IMPLEMENTATION

REPORT

viii

CHAPTER

1 1

INTRODUCTION

1 1.1

Background

1 1.2

Problem

Statement

2

1.3

Objectives of

Study

3 1.4

Project

Approach

3

CHAPTER

2

6

LITERATURE

REVIEW

6 2.1

Overview

6

2.2

Embankment

Design

6

2.3SurficialStability 8 2.4

Construction

Practices

9

CHAPTER

3

12

EMBANKMENT

WIDENING

SURVEY

12

CHAPTER

4

14

SITE

EVALUATIONS

14

4.1 Sites

Evaluated

14

4.2

Failed

Sites 14

4.2.1 1-69,

Madison

Co., GreenfieldDistrict

(R-20882)

14 4.2.2 1-69,

Grant

Co., Fort

Wayne

District

(R-19972)

32

4.2.3

Calumet

Avenue

Interchange,

Lake

Co.,

LaPorte

District

(R-19181)

39

4.3

Successful

Sites

41

4.3.1

Wallen

Road,

Allen Co.,Fort

Wayne

District

(B-21135)

41

4.3.2

U.S.

421

Wanatah, LaPorte

Co.,

LaPorte

District

(B-21433)

44

4.4. State

Road

1,St.

Leon,

Dearborn

Co.,

R-20879

47

CHAPTER

5

48

SUMMARY

AND

CONCLUSSIONS

48

5.1

Discussion

48

5.2

Grubbing and

Benching

48

5.3

Compaction and

Strength

ofFill Soils

49

5.4

Compatibility

inthe

Permeability of

FillSoils

50

5.5

Controlling Surface

Water

Runoff

50

5.6

Considering

the

Presence

and Flow

of

Groundwater

within

the

Embankment52

5.7

Slope

Inclination

52

5.8

Recommended

Changes

to

INDOT

Standard

Specifications

54

Ill 5.9

Conclusions

55

CHAPTER

6

₅₇

RECOMMENDATIONS

57

ACKNOWLEDGEMENTS

58

REFERENCES

59

IV

LIST

OF TABLES

Page

Table

3.1.

Summary

of responsesfor

embankment

widening

survey 13

Table

4.1. Sideslope steepeningprojectsites 16

Table

4.2. Field

compaction

test data for1-69,

Madison

Co.

GreenfieldDistrict 17

Table

4.3.

Laboratory

strengthtest data, 1-69,

Madison

Co.,GreenfieldDistrict

22

Table

4.4.

Standard

Proctortest data, 1-69,

Madison

Co., GreenfieldDistrict

25

Table

4.5.

Sand-cone

testdata, 1-69,

Madison

Co., GreenfieldDistrict

25

Table

4.6. Additional

sand-cone

testdata, 1-69,

Madison

Co., GreenfieldDistrict

27

Table

4.7.

Index

test data,1-69,

Grant County,

Fort

Wayne

District

37

Table

4.8.

Sand-cone and

standard Proctortest data, 1-69,

Grant County,

Fort

Wayne

District

38

Table

4.9. Field

compaction

testdata for

Wallen

Road

Approaches,

Allen Co.,Fort

Wayne

District

44

Table

4.10. Field

compaction

testdata forU.S.

421

Wanatah,

LaPorte

Co.,

LaPorte

District

47

Table

5.1.

Recommended

slopeinclination as afunction offill plasticity

54

LIST

OF

FIGURES

Page

Figure2.1.

Recommended

method

of

benching

(IndianaState

Highway

Commission

1971)

11

Figure4.1. Site location

map,

1-69,

Madison

County,

GreenfieldDistrict

(Anderson

South Quadrangle,

Indiana) 15

Figure4.2. Atterberg limits data, 1-69,

Madison

County,

GreenfieldDistrict 19 Figure 4.3. Activity of

embankment

soils,1-69,

Madison

County,

GreenfieldDistrict

19

Figure 4.4.

Standard

penetration testdata

and

water

content profiles, 1-69,

Madison

County,

GreenfieldDistrict

20

Figure4.5.

Cone

penetrometer

test data,

CPT-710,

Sta.

18+874,

O.S.

23.48m

It., 1-69,

Madison

County,

GreenfieldDistrict

23

Figure4.6.

Cone

penetrometer

test data,

CPT-720,

Sta.

18+838,

O.S.

21.34m

It., 1-69,

Madison

County,

GreenfieldDistrict

24

Figure4.7.

Standard

Proctortest data

and sand-cone

data, 1-69,

Madison

County,

GreenfieldDistrict

26

Figure4.8. Vertical

deformation

data, 1-69,

Madison

County,

GreenfieldDistrict

28

Figure4.9. Horizontal

deformation

data,1-69,

Madison

County,

Greenfield District

30

Figure4.10. Site location

map,

1-69,

Grant

County,

Fort

Wayne

District

(Gas

City

Quadrangle,

Indiana)

33

Figure4.1 1.

Standard

penetration testdata

and

water

content profiles, 1-69,

Grant

County,

Fort

Wayne

District

35

Figure4.12. Site location

map, Calumet

Avenue

Interchange,

Lake

County, LaPorte

VI

Figure4.13. Site location

map, Wallen

Road,

Allen

County,

Fort

Wayne

District

(Cedarville

Quadrangle,

Indiana)

44

Figure4.14. Site location

map,

U.S.

421

Wanatah, LaPorte County, LaPorte

District

(Wanatah

Quadrangle,

Indiana)

46

Figure 5.1.

Schematic

of

Bench

Inclination

and

Perforated

Drain Placement

51 Figure 5.2.

Recommended

Slope

Inclination as a

Function

ofPlasticity

53

Vll

LIST

OF

SYMBOLS

A

c activity c' effective

cohesion

CF

clay fraction

D

depth

fs

push

cone penetrometer

sleeve resistance

FS

factorofsafety

i slopeinclination

h

liquidity

index

k

plasticity

index

OMC

optimum

moisture

content

determined

from

laboratory

compaction

test

<?c

push cone penetrometer

tip resistance

RC

relative

compaction

w

water

content

Win-situ in-situ

water

content

w

_p plastic limit Wl liquid limit

r

total unit

weight

Y

effective unit

weight

Ydry, in-silu in-situdryunit

weight

Ydry,max

maximum

dryunit

weight determined

from

laboratory

compaction

test.

Pdry,max.

maximum

drydensity

determined

from

laboratory

compaction

test

¥

effective stress friction angle

Vlll

IMPLEMENTATION

REPORT

Failures

have

occurredin Indiana

highway embankments where

the

embankments

were

widened and

steepenedin orderto facilitateconstruction oflonger, safer

acceleration

and

deceleration lanes,

and

toincrease the trafficcapacity

and

efficiency of existing thoroughfares.

This

study consisted of aninvestigation into the cause of these

failures.

The

results ofthe investigations indicatethat failure ofthe

widened

embankments

resulted

from

sub-standard

compaction

offill,

and

inadequate

benching

intothe original

embankment.

Surface

water

infiltration

from

the

roadway

run-off contributed to the

problem,

possibly saturating

and

softeningthe soils. It is

concluded

thatthe slopefailures

investigated

would

not

have occurred

if

INDOT

Standard

Specifications

were followed

during construction, therefore,it appearsthatthe

primary cause

offailure isthe lack of appreciation ofthe potential risk

by

the parties involved.

Several

recommendations

are

provided

tohelp prevent these types offailure in the

future.

The recommendations

can

be grouped

intothree categories: 1)modificationsto

existing

INDOT

Standard

Specifications; 2)

improved

project

documentation and

quality control practices;

and

3)

implementing

a

mechanism

for

communication among,

and

continuing technical educationof,

INDOT

personnel.

Suggested

modifications to the

INDOT

Standard

Specifications are

made

in this report.

Implementation

ofa

mechanism

to address

Items

2)

and

3) is a greater challenge.

It appears thatthe failures occurred

because

the parties

involved

did not appreciate

the potential for failure, thatis both

INDOT

and

contractor personnel. Construction supervision,

documentation, and

quality control testing

were

practicallynon-existent for

the failed projects. Part ofthe

problem

may

be

that

INDOT

technical personnel

responsible

with

the quality control ofthese projects are

being

spread toothin, that is a decision

must

be

made

as to

what

project, or

what

partofa project, requires priority

attention.

Ifquality controlpersonnel

understood

thatthe potential forfailure

was

a reasonableriskthen itis likely thatthe standard specifications

would

be

enforced.

IX

Qualitycontrol personnel

can

become

aware

ofthe riskoffailure

by

implementing an

effective

means

of

communication

offailures across the

INDOT

districts,

and by

providing

continued

technical training.

The

first

recommendation

is forthe

development

ofa technicalnewsletterthat

providesa short discussionofspecific projectsthat

encountered

constructiondifficulties, failures, orinnovative solutions.

This

newsletter

would

be

distributedto the district

engineers

and

construction techniciansto

improve

the

communication

process

and lower

the riskofsimilarfailures occurringinotherdistricts.

Itis also

recommended

that shortcourses

be developed

in

which

the technicians

and

districtengineerscan

review

specific technical topics.

These

short courses

could

cover

a varietyoftopics

and should be developed

in concert with

INDOT

personnel to

address specific priorityneeds. Itis envisionedthat a

2

or3

day

short

course could be

offered

on

a yearly basis duringthe winter

months

when

itis easierto schedule

around

construction operations.

The

courses

might

be

offered

over

a differentperiodinthree or fourparts ofthe state to

minimize

travel

and maximize

scheduling.

These

short courses

should

be developed by

persons with substantialdesign

and

construction experience.

It

should be recognized

that the costs associated with the

implementation

ofa

mechanism

for

communication among,

and

continued educationof, technical personnel

may

appear

significant.

However,

in

many

cases these costs

would

be

offset

by

the avoidingfailure ofa single project

where

the costofrepairs

can

be

much

greater.

CHAPTER

1

INTRODUCTION

1.1

Background

Existing

highways

in the Stateof Indiana are

widened

to facilitateconstruction of longer, safer acceleration

and

deceleration lanes,

and

to increase the traffic capacity

and

efficiency ofexistingthoroughfares.

Highways on

embankments

require special

consideration since the

embankments

are typically

widened

to increasethe

roadway

width.

Widening

of

embankments

and

highways

is also

employed on

overpass

approaches

when

bridges are

widened.

A

number

oftechnically

sound

solutions

can be

implemented

to

widen

existing

highways

on

embankments

including:

•

widening

ofthe

embankment

while

maintaining sideslope

geometry;

• _constructionofretaining structures atthe

embankment

toe

and widening

the

crest;

• steepening ofexisting sideslopes

while

maintaining thetoe; and,

• reinforcement

and

steepening ofexisting slopes while maintainingthe toe.

Steepening

ofexisting sideslopes while maintainingthe toe has significant cost

advantages over

other

methods:

• Additional right-of-way

does

not

need

to

be

obtained.

• _Fill

volumes

are significantly less thaniftheentire

embankment

is

widened

while maintaining original sideslope geometry.

• Costlyretaining structures

which

requireperiodic

maintenance

arenot needed.

• _{Costly reinforcement}isnot necessary,

and

the associatedinefficiency during construction is alleviated.

The

Indiana

Department

of Transportation

(INDOT)

has successfully

steepened

sideslopes ofexisting

highway embankments

to

widen

roadways; however,

a

few

failures

have

resulted. In certain instances, the failures

were minor

and

limitedto shallow sloughs

on

the steepenedslopes. Incases

where

the distress

was

more

severe, scarps

were

visible.

In

one

case, failure in a steepened sidesloperesulted in longitudinal cracksin the

pavement

and

on

the shoulder,requiring inconvenientlane closure

and

costly

reconstruction ofthe

embankment

using reinforced soil.

Due

to thecostlynatureofstabilization orreconstruction ofprevious failures,

and

ENDOT's

need

for an

economical

means

of

widening

existing

highways on embankments,

thisresearchproject

was

undertaken

toidentifythe cause(s) offailureforthree

embankment

widening

projects in the State ofIndiana,

and

to

modify

design

and

construction guidelinesto be

used

for future projects.

The

focus ofthestudyrelates to

failures in the

compacted

soils, not to cases

where

failures

occur

in

weak

foundation soils.

1.2

Problem

Statement

Steepening

the sideslopesofexisting

embankments

to increaselane

width

orto

add

additional lanes posestechnical

problems

fordesign engineers

and

practical,

implementation

problems

forconstruction personnel.

Steepening

ofexisting sideslopes

by

thedesign engineerreduces the

margin

of

safety

with

respect to slope stability ofan

embankment.

The

designer

must

considerboth the stabilityofthe

embankment, and

the stabilityofthe

wedge

offillthat is

placed

to

widen

the

embankment.

Preferentialfailure planes

can develop

atthe interface

between

the original

embankment

and

thefill placedto steepen the slope. Traditional stability

analyses

can be

used

toverify the stabilityofan

embankment

as aunit;

however,

these

methods

are notnecessarily applicable forevaluating the stabilityofthe

wedge

offill

placed

on

the sideslope.

Construction personnel are confronted with the practical

problem

of placingthe

additionalearthfill

on

an existing slope.

The work

area availableatthe toe

and

crest of

the

highway

istypically limited

by

siteconstraints, complicating

placement

ofthe fill.

Traditional

equipment

may

not

be

suitable forfill

placement

and compaction.

The

plans

and

specifications

may

not be sufficientlyclearto

convey

the design engineer's intentions,

and

standard specifications

on

site preparation

and

fill

placement

may

not adequately address

and

emphasize

the

importance

of construction

procedures

utilized to

constructthe steeper slopes. In lightofthis, the characteristics ofthe

steepened

slope

1.3

Objectives

of

Study

The

objectives ofthis study

were

to

determine

the

cause

offailure inrecently

widened

and/or steepened

embankments, and

to

develop

design guidelines

and

improve

construction specifications foruse inthe future.

The

proposed

guidelines

and

modificationsto the

INDOT

Standard

Specifications

were

developed

considering:

previous experiences with sideslope steepening;the strength characteristics of

compacted

soils; conventional constructionpractices;

and

thelimited availability ofquality control/quality assurance personnel

on

most

smaller sizedprojects.

1.4

Project

Approach

A

literature

review

and

survey ofState

and

Federal transportationagencies

was

performed

to collect current, availabledesign guidelines

and

construction procedures for sideslope steepening projects.

The

results ofthis

survey

are discussed in

Chapter

3.

A

totalofsix project sites

were

investigated.

Five

projects

were

evaluated

where

widening and

steepening ofexisting

embankments was

performed.

The

projects

evaluated

were

selectedinconcert with

INDOT

personnel

who

are

knowledgeable

of existing conditionsatpotential sites.

The

sixth siteinvestigated

was

nota

widened

embankment.

A

failure

occurred

in a recentlyconstructed

highway embankment,

and

an

investigation ofthe failure

was

made

atthe requestof

INDOT

personnel.

A

short

summary

ofthis investigationis included in thisreport.

Two

ofthe

widened

embankment

projects

can

be

categorizedas unsuccessful.

Unsuccessful

sideslope steepeningprojectsinclude projects

where

severe distress has

occurred

resulting inlane closure or

damage

to the

highway and where

costly repairs

were

required.

Two

successful

widened

embankment

projects

were

evaluated

where

the intentof

the design has

been

achieved,

and

where

distresshas not occurred within the steepened,

or

widened,

sideslope.

The

fifth

embankment

widening

projectinvestigated

was

initiallyreported as a

failed case,

however,

the site

had

already

been modified

tothe pointthat an investigation

could

notbe

completed.

A

briefpresentation

was

made

at

INDOT'

s annual technical

retreat

(Turkey

Run, 1997)

at

which

additional

examples

offailed sections

were

sought,

however,

no

new

failedsections

were

reported.

The

initialstepinprojectevaluation

was

the collection ofavailable design

documents and

construction recordsforthe selected projects.

Review

ofthis

documentation

was

performed

in an attempt toidentify

key

aspects of individualprojects that

may

have

contributed tothe projects

being

categorized as successful orunsuccessful. In general,

very

littleinformation

was

available in

terms

of engineering design

documents,

fieldobservations duringconstruction,oras-built

drawings

for these projects.

For

the

most

part qualitycontrol tests

were

limitedto theright-of-waywith

few

tests

conducted

in the

widened

slopes.

Investigations ofthe unsuccessful projects

involved

standard,

proven

field

investigationtechniques

and

laboratorytests. Fieldtests included:

•

Borings

with standardpenetration tests

(SPT)

to evaluatethe stratigraphy

and

consistency ofthefill.

•

Cone

penetration tests to evaluate the stratigraphy

and

consistency ofthe fill.

• Testpits toevaluate the stratigraphyofthefill

and

to collect

samples

for laboratorytesting. Test pits

were

alsouseful for verifyingor evaluating construction techniques includingstripping,

benching

and compaction.

• In-place density testing utilizinga

sand-cone

to evaluate the in-situdensityofthe

fill,

and

topermit characterization ofstrength

based

on

in-situdensities for

samples remolded

in the lab.

Lab

testing

performed

as part of the investigationsincluded:

•

Index

testingforclassification,

and

correlation toengineering parameters.

•

Compaction

testingto identifythe moisture-densityrelationship for the soils

investigated.

• Strength testing toevaluate the drained

and undrained

shear strength

characteristics ofthe

compacted

soils. Testing

was

performed on

remolded

Investigations ofsuccessful projects

were

also

performed.

The

in-situ densities

and

theshearstrength characteristics ofthe

compacted,

sideslopefill

were

ofparticular

interest.

Information

gathered

from

these projects is

compared

to thatgathered

from

unsuccessfulprojects.

CHAPTER

2

LITERATURE

REVIEW

2.1

Overview

Methods

forevaluating thestability ofslopes,

whether

constructed ornaturally

occurring, arewell

documented (Bromhead

1986,

Duncan

et. al. 1987);

however,

little

documentation

existsregarding thestability of steepened sideslopes orsidehill fills.

The

parameters

which

determine

the stabilityof steepened sideslopes are the

same

parameters

which

determine

the stability of

embankment

sideslopes

and

naturallyoccurring slopes.

Specifically, these

parameters

consistofthe shearstrength, unit weight,

and

stress history

ofthe soil,

and

the slope geometry.

2.2

Embankment

Design

Slope

designfor

highway

projects involves evaluatingspecific slope geometries

that satisfy particular

highway

design requirements (e.g., right-of-wayconstraints, lane

width

requirements, etc.). Typically, detailed slope analysis

and

designis unwarranted,

and

thedesign engineerrelies

on

previous experienceforcurrent design geometries.

Where

shallow

slopes

(<2H:1V)

are constructed, this practiceis generally suitable;

however,

when embankments

slopes

exceed

2H:1V,

or only higherplasticity soils are available as fill, furtheranalysesare warranted.

Methods

specifically applicable toevaluatingthe stabilityof steepenedslopes

were

not

noted

inthe literature.

Huang

(1977) presented stabilitycoefficients forsidehill

benches.

The

coefficients arepresentedinchart

form

and

are

based

on

the Fellenius

method

ofslices. Construction of

benches

inthe existing slopeis not considered,

nor

is

the potential for preferential failure planes.

Ifthe steepened slopes are consideredasan integral partofthe

embankment,

analyses for potential

deep and

shallowrupture surfaces

can

be performed.

Eitherlimit

equilibrium orfinite

element

analyses

methods

are applicable. Simplified charts,

hand-calculations, spreadsheets, or

computer programs

can be

used

for limitequilibrium

oflimitequilibrium

and

finite

element

analysis

methods was

recentlypresented

by

Duncan

(1996).

Successful design of slope geometriesis

dependent

on

the appropriateselection of

shearstrength characteristics for the soils

comprising

the earth structure orslope. In addition, a

thorough

understanding of

environmental

factors

which

alterthe shear strength ofthese soils

over

thedesignlife ofthe structure isrequired.

Leonards

(1955) indicatedthatunlessthe shearstrength characteristics of asoil

over

the design lifeofthe structure are

known

results ofstabilityanalyses will

be

misleading.

Embankments

and

steepened sideslopes are typicallyconstructed of

compacted,

cohesive soilsin Indiana

highway

projects. Soils are

compacted

to

improve

their engineeringproperties,

and

this

improvement

is conveniently

measured

in

terms

of density

and moisture

content.

Compaction

decreasesthe permeability

and

compressibility,

and

typically increases the shearstrength ofsoil.

Since

thestabilityof

embankments

and

steepened sideslopes is afunction oftheshearstrength ofthe soil, the

importance

of

compaction

is significant.

Classic,

fundamental

papers

on

compacted,

cohesive soils

have

attributed the shearstrength characteristics of these soils toclay

and

pore water

chemistry,

and

fabric structure

(Lambe

1958 and

Seed

et. al. 1959).

Of

particular

importance

to the designeror

constructor,

however,

isthe application of these

fundamental concepts

to

everyday

design

and

construction with earthen materials.

These

practical considerations

with

respectto

undrained

strength of

compacted,

cohesive soils

were

presentedin detail

by

Leonards

(1955),

Lambe

(1958),

Seed

et. al. (1959),

and Casagrande

et. al. (1962)

and

their

immediate importance

tothe design of steepened slopes are as follows:

•

_An

increase inthe drydensityof cohesive soils

by

compaction,

at a constant

water

content, results in an increase in the

undrained

shear strength ofthe soil.

•

_The

undrained

shearstrength ofa

compacted

soil

prepared

at aconstant densitywill typically decrease with increasing

water

content.

The

actual

magnitude

ofthis

change

is soil specific,

and

can

only

be

verified

by

laboratorytesting.

Soils

compacted

dry of

optimum

water

content

tend

to experiencegreater

changes

indensity

and

strength withincreases in water contentthat

might be expected

during the design life ofthe structure.

When

subjectedto

an

increasein

water

content, soils

compacted

dry of

optimum

may

swell at

low

confining stresses or collapse athigh

confining stresses.

Moreover,

soils

compacted

dryof

optimum

experience dramatic reductions in

undrained

shearstrength withincreases in

water

content. Soils

compacted

wet

of

optimum

tendtodisplay

more

axial shrinkage

upon

drying thansoils

compacted

dry

of

optimum,

however,

this is rarelya

concern

forIndiana's climate

once

a vegetative

cover

has taken hold.

The

practical implications oftheseobservations

made

from

examining

trends in laboratory dataare useful tools for the design engineer.

2.3SurficialStability

Steepened

slopes constructed of

compacted, cohesive

soils

may

alsoexperience sloughing, the

development

of shallowfailures with rupture

zones

parallel to the slope of the soil mass.

Sloughing

failuresin

compacted

clays

have

been

documented

in

Ohio

(Wu

et. al.

1993

),

and

California

(Day

1994).

Lambe

and

Whitman

(1969)

indicate thatthis

type offailure results

from

weathering

ofthe surficial soil.

Weathering weakens

surficial soils, destroying

most

ofits cohesion.

The

factorofsafety forthis condition

can be

analyzed

using (eg.

Day

1989):

c'+y'

D

cos2itan0'

FS =

—

-yDsmicosi

The

equation isderived

assuming

aninfinite slope with

seepage

parallel to the slope to a depth,

D.

Day

(1994)

recommends

selecting effective strength parameters for

this analysis cautiously, indicating thateffective strength

parameters determined

from

strength tests

performed

athigh confining pressures

may

not

be

appropriate. Triaxial strength tests

performed

at high confining pressures

may

over

predict effective cohesion, resulting inmisleading conclusions withrespectto stability. Instead,

Day recommends

performing

consolidated-undrained

(CU)

triaxial

compression

tests

on

compacted

specimens

at

low

confining pressures

which

model

confiningstresses representative of

shallow

depths

on

the slope.

When

modeling

very small

confinement,

shear strength can

9

Based

on

experience

gained

in California,

Day

(1994)

recommends

the following

for analysis ofsurficial stability:

•

Determine

appropriate depth ofsaturation zone,

D,

based

on

local

weather

conditions.

• Prepare laboratory

samples

that reflect

moisture

content

and

density anticipatedduring field

compaction.

•

Analyze

shear strength at

low

confiningpressures, representative offield

conditions

•

Determine

the factorof safetyusing equation 2.2.1. Ifthe factorofsafety

is strongly

dependent

on

effective

cohesion

or ifthe effective

cohesion

is

greaterthan

approximately

0.9 kPa, verify the effective

cohesion

using

other

methods.

InCalifornia the

minimum

recommended

factorofsafety is 1.5 forsurficial slope

stability (Dept. ofthe

County

Engineer

1978).

2.4

Construction

Practices

INDOT

(1993)

Standard

Specifications indicate that

benching

and

compaction

of

soil

used

toconstruct

embankments

isrequired. Specifically,

where

an

embankment

is

constructed

on

natural orfilled slopes

4H:1V

or steeper,

benches

are specified.

The

minimum

width

ofthe

benches

is

3m,

unless otherwise indicated.

Benching

is further

emphasized

inthe IndianaState

Highway

Commission's

(1971)

Road

Design Manual,

as

presentedinFigure 2.1.

The

Standard

Specifications indicatethat

embankment

soils are to

be

compacted

to

95%

ofthe

maximum

dry density as

determined

by

AASHTO

T99

(Method

A).

The

allowable moisture content range is -2to

+1

percentage point relative to the

optimum

moisture content

(OMQ.

The

specifications also dictate that

embankment

material shall

be

placed in

uniform

level layers

and

thatthe liftthickness

does

not

exceed

8 inches.

Appropriate construction practices are alsopresented in the

Guide

to

Earthwork

Construction

(TRB

1990).

The

primary

benefit of

benching

isthatfill,

when

placed

on

a

hillsideor existing

embankment, becomes

keyed

intothe original soils.

Benching

also

removes

the potential failure surface that

would

be

present

between

the fill

and

the

10

original

embankment,

if

benching

was

notperformed.

TRB

recommends

that

benches be

constructed

where

existing slopes are steeperthan

3H:1V, and

that

benches be

FINAL

REPORT

FHWA/IN/JHRP-99/4

EMBANKMENT

WIDENING

DESIGN

GUIDELINES

AND

CONSTRUCTION PROCEDURES

by

Richard

J.

Deschamps,

Principal Investigator, Christopher S.

Hynes, Research

Assistant,

and

Philippe

Bourdeau,

Principal Investigator

School

ofCivil

Engineering

Purdue

University

JointTransportation

Research

Program

ProjectNo.:

C-36-36AA

FileNo.:

6-14-27

Prepared

in

Cooperation with

the Indiana

Department

of Transportation

and

the U.S.

Department

of Transportation

Federal

Highway

Administration

The

contents ofthis reportreflectthe

views

ofthe authors

who

areresponsible forthe facts

and

accuracy ofthedatapresented herein.

The

contents

do

not necessarily reflect

the official

views

ofor the policies ofthe

funding

agencies.

The

report

does

not constitute a standard, specification,orregulation.

Purdue

University

West

Lafayette,Indiana

47907

11

TYPICAL

METHOD

OF BENCHING

.Sid»MiBBwncning

Arwo Of Tworinq DownFill

Cutting Ground

-'-trrrrfl/i**. 10

10*

GENERAL NOTES

DoNotinkLinat On Cross-Sections

Z. OoNotinduds End ArwasInAreas And Voiumss Shown On

Crott-Sections

ineludwTh« voiumss ForBenchingInBoth TheCut And Fill

Quantifies ShownOn Th« Plan 8 Profile SheetFor The Bolance Or BcioncesIn Which The Ouontihes Occuc Add Th« following Not* "TheAboveQuantities Incbdvs

CYS Of Cut And CTS Of Fill For Benching"From Sta To Sta.

Figure2.1.

Recommended

method

of benching

(IndianaState

Highway

Commission

12

CHAPTER

3

EMBANKMENT

WIDENING

SURVEY

A

survey of Federal

and

State transportation agencies

was

conducted.

The

goal of the

survey

was

to obtaininformation regarding these agencies' experiences with

steepeningexisting

embankment

sideslopesin an effort to

widen

existing

highways.

The

findingsofthis survey are

summarized

in

Table

3.1.

The

information

provided

by

each

transportation

agency

varied. Thisvariation is attributedto:

• the differinggeologic deposits in

each

state;

• therespective design

and

construction requirements establishedtoconstruct

on

thesedepositsorto utilize these materials forconstruction;

• the perspectiveofthe individual respondents (e.g.,is their

primary duty

geotechnical or structural design, construction oversight,

management,

etc.);

and,

•

each

respondents willingness toelaborate

on

theirrespective State'sfailures.

Even

withthe variation inresponses, certain trends

were

apparent regardingthe construction of unreinforced

embankments.

These

trends tendto indicate that the followingisrequired for successful

embankment

widening:

• benching;

•

compaction;

and,

• drainage.

The

use ofselectfills

was

nota

primary concern

ofthe respondents.

The

compatibility ofthe existing

embankment

soil with the

new

fill withrespect to

permeability

was

considered important.

The

surveyresults also indicate that unreinforced slopes

up

to 2:1

(H:V)

are typically

used

for

highway embankments.

No

design

documents

or

methodologies

fordesign of unreinforced, steepened slopes

were

provided

by

the respondents.

13

Table3.1. Summaryof responsesfor theembankment wxien1

StateorFederal Deportment

« Comments

AlabamaDOT

ArkansasStateHighway&Trans DepL

CaliforniaDOT OfficeofStrue ColoradoDOT

FloridaDOT OfficeofStrut;attributed tohvorostanc erasures. FloridaDOT District1&7

IdahoTransportationDept tcusingreinforcement-alsofailed.

IowaDOT lycase

KansasDOT Bureau ofMat

KentuckyTransportation Cabinet DivisionofMii-i

MarylandDOT Materials&Ri*

MichiganDOT Materials&Tifeaedl;lfromshouldersand poorconstruction.

MinnesotaDOT Construction<Sosoftfoundationsoils.

NebraskaDept.ofRoads ucttnll

NewJerseyDOT

NewYorkStateDOT GeotcchmcaJEni5-1

North CarolinaDOT North CarolinaDOT

OhioDOT OfficeofRoad

OregonDOT ensurestability. Planum*tonrmforceslopes steeper than1.5:1.

South CarolinaDOT jiycaie

TewsDOT Materials<fe_{Talents where}

fillhad P!>30

UnitedStatesDOT-FHWA

UnitedStatesDOT-FHWA EasternFeelers Notes:

1. Specification provided.

2. Designdocumentsprovided.

3. Embankmentstccpenmgperfor

m

edbut notforlanewidens

4. Cantileverwalls,MSEwalla,REwalls,gabionwalls,esc, 5. Rockutilized forembankmentconstructionor assurfacetzi

13

Slateor Federal

Department

DivilWB.Unrt Responded Experience wiEmbankment

Steeoenmg

Experience w/Distress RespondsRegarding

UmrmforcedSlopes

Slopes

OtherMethods ofWidening

Commend

Yes No Yes No StooefHVl Bene*11_* Wills**1

Rock(>1

x x X xl"

Failuresnotedmdecofillswrrhoiiihenchme .

x m *"' x x , x x 1.5:1(max.) x(" X x X X FloridaDOT FlondnDOT _

OfficeofSDeclaresStDesign

District1St7

* x

, 5 .

> 2:1(max-)

Noslidmefailures.VeneerfailuresatinterfacelantmtcdtonvdroiUbetreasures

IdahoTransportationDcpt IowaDOT

KansasDOT Bureau ofMaterialsStRocud)

DivisionofMaterials l * « 2:1(max.) «

—

*

NostandarddewtnmethodEvaluatedcasesbvcase

Usequarriedrockwhenslopes are steeper than2:1

.

MarvlnndDOT MaterialsStRocmh

MaterialsStTecbnotofjvDiv.

* £ X

x

1 MSEslooe1:1<tvnAHad6uhrremMSEiloot

Atmbutcs("ailme*to softmaterial outside proi-xted11fromthoukicrsandpoorconstruction. x x X 2:lftvp.l x(l) x X Tvmcallv concernedwnhglobal stabilitydue(otop foundationsoils.

x X X x Have had orobtcmswrtli1.51jlopes. reconstructto 1:3.

X X 2 IftVftl X1" _No

reinforcedifeocsconstructedto date•in theprocessofdesitrn though. CrcalechrncalEnRmeeTTnK Bureau x X 3Ktvn.) x * x X - StooefillandRcaornanrcssesusedonslopesto151

X X :Iftml x x Use rock olateon1_5:1ttoocs.

It X 2Iftvt.) * * x OfficeofRMdw»vEnerocerme X X X x

X X X 2:1-1.31Imal Compaction and drama^e prtmarv concernstoensurestability PlanningK>reinforceslopes steeperthan1,5'1.

x X X x Nostandard deartlimethod.Evaluatedcasesbyca:e.

Maicnab&Teal Division x z Shallowsurfaceflowsexperiencedmembankment: wherefillnodPl>30

x x X X X Nostandarddestgnmethod.Evaluatedcasesbvcare

UnitedSlate*DOT-FHWA Eastern FederalLoadsHifchsvavDrv X X » *-m _{laagagSgaagBs}

Notes:

I Specificanonsprovided.

1 Dcngndocuinctits provided.

3 Embankmentilccpcnragperformedbut not for lane wadcrting.

iCantilcvcT walls,MSEwalls,REwalls,Gabionwalls,etc

5 Rockutilized forembankmentconstructiono t,stonefill,plating,etc.).

14

CHAPTER

4

SITE

EVALUATIONS

4.1 Sites

Evaluated

Five

sites

where

embankment

widening

was

performed through

steepening of sideslopes

were

selected for evaluation.

Two

ofthesites areconsidered successful projects

and

threeofthe sites selected displayeddistress.

One

ofthe "failed" sites

could

not

be

fully investigated

because

conditions atthe site

were

altered since the distress

occurred.

The

location of

each

ofthese sites,extentofdistress,

and

a briefdescriptionof

each

projectis presentedin

Table

4.1.

Documentation

pertainingtothe design

and

construction ofthese projects

was

obtained

from

INDOT.

Documentation

obtainedincludedsite investigation records, designplans,

and

constructionrecords.

4.2

Failed

Sites

4.2.1 1-69,

Madison

Co., GreenfieldDistrict

(R-20882)

Contract

No.

R-20882

was

let

on

May

14, 1994.

The

project

involved

reconstruction of1-69

between

RP

22+96

to

RP

27+80.

Work

under

this contract included steepeningthe sideslope of the existing

embankment.

The

embankment

was

widened

from

approximately

Sta.

448+80

(PR-1),

west

ofthe bridge carrying1-69 over

old

SR

109

to Sta.

466+80, west

of

southbound

entrance

ramp

atExit26.

The

extentof the

widening

project

and

the site location ispresented inFigure 4.1.

The

embankment

widening

was

performed

toincrease the length ofthe

southbound

entrance

ramp

accelerationlane.

The

maximum

increasein

width

was

12 feet,

and

the toeoftheslope

remained unchanged.

Plans indicatedthat the

maximum

sideslope

when

regraded should

15

• • • 6~\,

^s&dTPjJS"-

•-=—II

_)r"

r

—

v

: •

"."••."•••"•If:-* fc|: !±5dUii::

Figure 4.1. Site location

map,

1-69,

Madison

County,

Greenfield District

(Anderson

South Quadrangle,

Indiana)

16

Table

4.1. Sideslope steepeningprojectsites.

County

District Contract

No.

Project

Type

Comments

Madison

Greenfield

R-20882

Extension

of

acceleration lane during

roadway

reconstruction.

Significantfailure, resulted

in longitudinal cracks

on

shoulder, settlement

and

lane closure.

Grant

Fort

Wayne

R- 19972

Extension

of

acceleration lane during

roadway

reconstruction.

Significant failure with an

approximately

350

foot

long

scarp, serious erosion

subsequent

to failure.

Lake

LaPorte

R-19181

Interchange

reconstruction

and

interstate widening.

Shallow

sloughs with

no

damage

to

roadway.

Allen Fort

Wayne

B-21135

Overpass

widening. Successfullycompleted.

LaPorte

LaPorte

B-21433

Overpass

widening. Successfullycompleted.

Subsequent

to

roadway

reconstruction distress

was

noted

on

thesteepened

sideslopes.

Deformation

was

severe

between

Sta.

451+87

and

Sta.

457+48

(i.e.,

between

thebridges

over

Conrail

and

old

SR

109)

and

longitudinal cracking alongthe shoulder of

the

road

and

inthe

pavement was

noted

followed

by

settlementofthe shoulder.

Repair

of

the sectionof

roadway

effected

was

attempted

and

additional asphaltic

pavement was

placedto true

and

level the

roadway

surface. Settlement continued,

however, and

it

appeared

as

though

the sideslopefill

had

failed.

Embankment

Design

and

Construction Plans

Design

documents

were

not available for the sideslope steepening project;thus,

implying

thatstability ofthe steepened

embankment

was

not

analyzed

priorto

construction.

The

construction plans did notadequately address the

embankment

widening. Sections for the

proposed widening were

not

provided

in the plans.

The

plans indicatedthat the

roadway

was widened

3.65 meters

and

the

maximum

sideslope

permitted

was 2H:1V. The

original sideslope,

however,

appears to

have been

atan

inclination of

2H:

1

V

priorto

embankment

steepening. Slopes

ended

up

being steepened

to as

much

as

1.4H:1V

atbridge cones,

and

to

1.6H:1V on

average along the

17

Construction

Records

As-builtplans forthis project

could

not

be

located. Field

compaction

data

was

provided

by

the District

and

is

summarized

in

Table

4.2.

The

nine tests indicatethat the

soil

was compacted

to densities greaterthan the

minimum

specifieddensityof

95%

ofthe

maximum

dry density as

determined

from

thestandardProctortest

(AASHTO

T99,

Method

A).

However, none

ofthe tests

performed

lie withinthe

steepened

sideslopes.

The

offset isreferencedto

PR-1,

thecenterline for the project.

The

interface

between

the existing

embankment

and

the

wedge

offill placedto steepen the sideslopelies

60

feetleft

ofthe centerline.

This

appearsto indicatethatthetests in

Table

4.2

were

performed

for the

subgrade

soils orbasecourses.

The

absence

of

compaction

dataforthe sideslopes suggeststhat

no

compaction

tests

were performed

on

material placedto steepen the sideslopes.

Table

4.2. Field

compaction

test datafor 1-69,

Madison

Co.

GreenfieldDistrict.

Test

Date

Station (ft) Offset(ft) _{/dry, in-silu}

w

in-situ

RC

(%)

(2)

No.

(1)

(kg/m

3)

(%)

61 (S) 8/15/94

461+50

24<3)

₂₂₂₈

_{3.6 111.1}

72

(S) 8/16/94

455+10

48

LT

2177

6.9 108.5 (S) 8/17/94

461+70

29

LT

1955

5.4 97.4 (S) 8/17/94

461+50

24

LT

2097

5.1 104.5 (S) 8/17/94

461+60

19

LT

1991

6.7 99.2

1(S)

8/19/94

449+70

25

RT

2080

8.7 103.6

2(S)

8/19/94

456+00

27

RT

1969

8.6 98.1

3(S)

8/19/94

452+25

24

RT

2037

9.0 101.5 (S)

9/23/94

467+15

16

LT

2319

2.2 115.6

Notes: (1) Letterfollowingtestnumberindicateswhetherthedensitywasdeterminedusing asand-cone(S)

or nuclear densitygauge(N).

(2) Relativecompactionisequalto thefielddry density dividedbythe

maximum

drydensityfor

thesoil.

(3) Direction ofoffsetwasnot indicatedinthe original projectdocumentsreviewed.

18

Post-Failure Investigation

Data

A

post-failure investigation

was

performed by

INDOT.

The

field

work

was

performed

between

December

1994

and

March

1995.

As

part ofthis investigation

seven

borings

were

advanced and

split-barrel

samples

were

collected.

Index

tests,including grain size distribution,

hydrometer and

Atterberg limits analyses

were

performed

on

select split-barrel samples.

The

index testdatahas

been

summarized

inFigures 4.2

and

4.3.

As

indicated

by

the

index

testdata, thesoilsin the original

embankment

and

those

used

to steepen the sideslopes are primarily

low

plasticity, finegrained soils, classified as

CL

in

accordance with

the

Unified

Soil Classification

System

.

The

activity,A, ofthese

soils is

approximately

0.75

on

average, indicatingthatillite is the

primary

clay mineral.

The

SPT

data

and moisture

contentprofiles forthe borings are presentedin Figure

4.4.

The

estimated

maximum

depth

offill placedto

widen

the

embankment

isindicated

on

the profiles

and

is

based

on

sideslope geometry.

SPT

dataindicates that fill soils

beneath the

pavement

are generally looseto

medium

dense

(B-l

and B-5)

or

medium

stiff

(B-3).

On

the sideslope

(B-10

and

B-ll), surficial soils are very loose or very soft;the consistencyordensity ofthese soils haslikely

been

altered

by

the slide,

and

by

surface waterinfiltration.

With

increasing depth, the

embankment

soils

becomes

stiff.

Density

tests

were

performed on

select split-barrel

and

undisturbed tube samples.

Dry

densities

ranged

from

1580

to

2133

kg/m

J(98.6 to 133.11b/ftJ) for the soilsanalyzed.

However,

the datais notreflective ofthe density ofthe fill placedin the sideslopeduring

steepening.

The

densitiesreported

by

INDOT

primarily reflectthe density ofnaturally depositedsoils atthe toe ofthe slope or the densityofthe soils

comprising

the original

embankment.

INDOT

contractedEarth Exploration ofIndianapolis, Indianato

perform

three

additional borings atthe toeofthe

embankment,

and perform

consolidated,

undrained

(CU)

triaxial tests with pore pressure

measurements on

remolded

and

undisturbed

specimens. This

sampling and

testing

program

was

undertaken to establish design parametersfor slope stabilization. Laboratory strength test data is

summarized

in

Table

19 70

T

60 -; 50 : 40-: .2 30-: 20-: 10 ; 40 50 60 LiquidLimit,tv,(%) 80 90 100

Figure4.2. Atterberg limits data, 1-69,

Madison

County,

Greenfield District.

oINDOTData

30

-20

10

-Illite(A=0.9) Kaolinite(A=0.38)

10 20 30

ClayFraction,CF(<2n)(%)

40 50

Figure 4.3. Activity

of

embankment

soils, 1-69,

Madison

County,

Greenfield District.

20

i J

O M

—

CO

>

z

H

0. WO (Ul)U0IJBA3[g < a ED

—

r~l a CO ZJ •c > o CO

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(ai)uoue.\3|3

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U

IS

o

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CO •a c/3

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21 BoringB-5/B-5A SPTN-Valuesand w (%) 5 10 15 20 25 30 35 31.5 30 -28.5 27 -25.5 : 24 -:

I

22.5 n > 21 19.5 -: 18 -; 16.5 15 13.5

*#**

FillInterface BoringB-10 SPTN-Values and

w

(%) 5 10 15 20 25 30 35 31.5 30 28.5 • 27 -: 25.5 24

?

I

22.5 > u

u

21 19.5 18 16.5 15 13.5

-O—

N-Value BoringB-11 SPTN-Values and w (%) 5 10 15 20 25 30 35 31.5 30 28.5 27 -25.5 24

I

22.5 -> 1X1 21 19.5 18 -: 16.5 15 13.5

-e—

N-Value

Figure4.4 (con't.). Standard penetrationtest data

and water

content profiles, 1-69,

Madison

County,

GreenfieldDistrict.

0.6-1.2

34

1.2-1.8 30.2 10.8 1.2-1.8 32.8

Bag

sample

( ) 36.6

Bag

sample** 38.6 22

Two

cone

penetrationtests

(CPT)

were

performed

atthis project site

by Purdue

University.

CPT

dataare presentedinFigure 4.5

and

Figure4.6.

The

tests

were

performed

adjacenttothe shoulder ofthe

highway,

offset

approximately

6 feet

from

the

edge

of

pavement.

CPTs

were

performed

to evaluate theconsistency ofthe

embankment.

CPT

provides acontinuous profile of sub-surfacestratigraphy; therefore, it isa superb

tool foridentifying soft

zones

or other discontinuitiesin natural

and

man-made

deposits.

No

apparent

weak

zones

or discontinuities

were

identifiedat the locationsofthe

CPTs.

Table

4.3.

Laboratory

strength testdata, 1-69,

Madison

Co., GreenfieldDistrict.

Sample

Depth

(m)

tp\°) c'(kPa)

RB-1, ST-1

RB-1, ST-2

RB-2,

ST-1

RB-1,BS-1

RB-2.BS-1

Notes: (1) Samplecompactedto

=97%

ofthe

maximum

dry density determinedby

AASHTO

T-99 andat

vv= 11.7%. Pory.max.= 1921 kg/m

3

,

OMC

= 12.3%.

(2) Samplecompactedto

=97%

ofthe

maximum

dry densitydeterminedby

AASHTO

T-99 andat

w

=

11%. _pory,max.

=

2009 kg/m

3

,

OMC

= 10.9%.

Five

standard Proctortests

were performed on

soilscollected

from

the failed

embankment. Four

ofthe samples,

S-101 through

S-104,

were

randomly

collected.

The

fifth

sample

was

a

composite sample

consisting ofsoils

excavated

from

five

sand-cone

densitytests.

Summaries

ofthe standard Proctor

and

the five

sand-cone

densitytests are

presentedin

Table

4.4

and Table

4.5, respectively.

As

indicated in

Table

4.4, the

maximum

dry density

determined

from

standard Proctortests

ranged

from

1,925 to 2,024

kg/m

3,

and

the

optimum

moisture content

ranged

from

10.5 to 13.3 percent.

Sand-cone

testsindicate that relative

compaction

ofthe fill

used

to

widen

the

embankment

ranged from approximately

79

to

90

percent. In addition,

23 . f -|\

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00

25

from

3.7 to 8.7 percent

wet

of

optimum.

These

data

and

themoisture densityrelationship arepresentedin Figure4.7.

Table

4.4.

Standard

Proctortest data, 1-69,

Madison

Co., GreenfieldDistrict

Sample

_PDry,max.

(kg/m

3)

OMC

(%)

Wi

(%)

_h

S-101

2012

10.9

29

14

S-102

1993

12.0

29

13

S-103

1935

13.2

30

14

S-104

1925

13.3 31 16

Composite

2024

10.5 -

-Table

4.5.

Sand-cone

testdata, 1-69,

Madison

Co., GreenfieldDistrict

Test _Pdry,

in-(kg/rr situ

RC

(%)

w

in-situ

(%)

Wi

(%)

k

S-110

1608

79.45 15.2

27

12

S-lll

1824

90.12 14.2

29

15

S-112

1600

79.05 14.6

26

12

S-113

1778

87.85 15.9

28

13

S-114

1597

78.90 19.2

30

16

Three

additional sand-cone tests

were performed

in the fill.

Two

ofthese tests,

S-200 and

S-201

were

performed

in original

embankment

soils,

and

the third test

was

performed

in soilsplaced

on

the slope.

The

results ofthesetests are presentedin

Table

4.6.

Although

limitedtesting

was

performed on

the soils

comprising

the original

embankment,

the dataindicates that thesesoils exist atgreater densitiesthan those

used

to

widen

the

embankment.

26 _' ' I I| I II I I II I I || || M | || | j|

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o

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ea t»

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+s

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c

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g

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3

00

27

Table

4.6. Additional

sand-cone

testdata, 1-69,

Madison

Co., GreenfieldDistrict

Test

_{Pdry,in-situ(kg/m}3 )

Range

of

RC

(%)

{1)

_w

in._situ

{%)

S-200

1826

90.2 - 94.9

153

S-201

1846

91.2-95.9

14.9

S-202

1794

88.6-93.2

11.8

Notes: (1) Basedonrange of

maximum

drydensitiesdeterminedfromstandardProctortestsaspresented

inTable4.4.

Vertical

and

horizontal

deformation

was measured by

INDOT

and

ispresentedin

Figures 4.8

and

4.9, respectively.

Review

ofvertical

deformation

datareveals thatthe greatestsettlement occurredin the sideslope, nearthe shoulder ofthe

road and

decreased with increasing distance

from

the centerlineof1-69.

No

vertical

displacement

was

noted

atthe toe ofthe

embankment

or

beyond.

Horizontal

deformation

datacovers a relatively short

time

period.

Aside

from

an

anomalous

readingat Sta.

452+00,

no

significant horizontal

deformation

was

noted atthe

toe ofthe slope. Horizontal displacement at the crest

was

lessthan

300

mm

for thetime period considered.

The

data indicate that vertical

and

horizontal

deformations were

greatestnearthe shoulder oftheroad,

and were

confined tothe slope.

The

maximum

fill depth

was

atthe shoulder oftheroad.

No

deep-seated

movement

was

noted

at ornearthe toe ofthe

structure.

One

testpit

was

excavated

inthe sideslope ofthe

embankment,

and

the

removal

ofsoils

comprising

the

wedge

offillplaced

on

the sideslope

was

observed

to visually identify potential discontinuities in the fill.

The

following is a

summary

ofpertinent observations:

•

The

original

embankment

soils

had

clearlydefined horizontal lifts,

accentuated

by

colorvariations.

No

such layering

was

noted

in the fill placed

above

the original

embankment;

this fill

had

a

jumbled

appearance.

28 12/1 30 -30 -60 -90 -120 -150 -180 -210 -240 -2704 -300 3/94 12/27/94 Offset(m)

—

e-

20.02

—0—

24.13

—A—

35.42

—

e—

40.23 Station452+00 1/10/95 1/24/95 2/7/95 2/21/95 3/7/95 3/21/95 ^s= =$= =9 Station453+00 1/24/95 2/7/95 2/21/95 3/7/95

>

-24U -: 3/21/95 -60 ₊ -90 -120 ! -150 -j -180 -: -210 -240 --270 • ! -300 ! Offset(m) Station454+00 12/27/94 1/10/95 1/24/95 2/7/95 2/21/95 3/7/95 3/21/95

-B-

1987 -©—24.00

-A—

27.70

-O—

36.50

H—

40.98

29

>

-12/1 30 -30 -60 -90 120 •150 180 210 240 270 300 3/94 12/27/94 Station455+00 1/10/95 1/24/95 2/7/95 3/21/95 Station456+00 3/7/95 3/21/95 Station457+00 2/21/95 3/7/95 3/21/95

Figure

4.8 (con't.). Vertical

deformation

data, 1-69,

Madison

County,

Greenfield

District.