theadva
tagesofpredrai
i
gi
somei
sta
cesWithmixedsoilsfaceexcavatio
maybe
ecessarytoacceleratedrai
ageworksCBRtesti
gofboulderclaysoilsalso
eedscarefulco
sideratio
mai
lywiththepreparatio
methodemployedDesig
e
gi
eers
eedtobeawareofthisasitca
havea
orderofmag
itudediffere
cei
resultsStaticcompactio
ofboulderclaysoilsisadvisedascompactio
withthe25or45kgrammerofte
leadstohighexcessporepressuresbei
gge
eratedhe
ceverylowCBRvaluesca
resultAlsocuri
gofcompactedboulderclaysamplesisimporta
tasthisallowsexcessporewaterpressurestodissipate
5ENGINEERINGCLASSIFICATIONOFSOILSI
accorda
cewiththeNRASRWge
eralcohesivefilliscategorisedi
Table61asfollows
2AWetcohesive2BDrycohesive2CSto
ycohesive2DSiltycohesiveThematerialpropertiesrequiredforacceptabilityaregive
a
dthedesig
e
gi
eerthe
determi
estheuppera
dlowerbou
dlimitso
thebasisofthelaboratoryclassificatio
a
de
gi
eeri
gperforma
cetestsIrishboulderclaysoilsarepredomi
a
tlyClass2CClause612oftheSRWsetsoutcompactio
methodsTwoproceduresareavailableMethodCompactio
E
dProductCompactio
E
dproductcompactio
isco
sideredmorepracticalespeciallywhe
goodcompactio
co
troldatabecomesavailableduri
gtheearlystagesofa
earthworksco
tractAmi
imumTargetDryDe
sityTDDisco
sideredveryusefulfortheco
tractortoworkwithasamea
sofchecki
gcompactio
qualityO
cethematerialhasbee
approveda
dmeetstheacceptabilitylimitsthe
i
situde
sityca
bemeasuredpreferablyby
ucleargaugeorsa
dreplaceme
ttestswherethesto
eco
te
tislowAsplaci
ga
dcompactio
ofthefillprogressesthei
situTDDca
becheckeda
d
o
co
formi
gareasquicklyrecog
iseda
dcorrectiveactio
take
Thisprocessrequiresthedesig
e
gi
eertoreviewthefieldde
sitieswiththelaboratorycompactio
plotsa
devaluateactualwith‘theoreticalde
sities’
f6SUPPLEMENTARYGROUNDINVESTIGATIONMETHODSFOREARTHWORKSThemoretraditio
almethodsa
dprocedureshavebee
outli
edi
Sectio
2Thefollowi
gareexamplesofmethodswhicharebelievedtoe
ha
cegrou
di
vestigatio
worksforroadprojects
Phasi
gthegrou
di
vestigatio
worksparticularlythelaboratorytesti
gExcavatio
sampli
gi
deeptrialpitsLargediameterhighqualityrotarycoredrilli
gusi
gairmistorpolymergel
tech
iquesSmallscalecompactio
trialso
pote
tiallysuitablecutmaterial
61PHASINGPhasi
ggrou
di
vestigatio
worksforma
ylargeprojectshasbee
advocatedforma
yyearsthisisparticularlytrueforroadprojectswheresig
ifica
tamou
tsofgeotech
icaldatabecomesavailableoverashortperiodO
themajorityoflargegrou
di
vestigatio
projects
operiodisleftto‘digest’orreviewtheprelimi
aryfi
di
gsa
dr