DESIGNANDEXECUTIONOFGROUNDINVESTIGATIONFOREARTHWORKS
PAULQUIGLEYFGSIrishGeotech
icalServicesLtd
ABSTRACTThedesig
a
dexecutio
ofgrou
di
vestigatio
worksforearthworkprojectshasbecomei
creasi
glyimporta
tastheavailabilityofsuitabledisposalareasbecomeslimiteda
dcostsofimporti
ge
gi
eeri
gfilli
creaseA
outli
eofgrou
di
vestigatio
methodswhichca
augme
ttraditio
ali
vestigatio
methodsparticularlyforglacialtillboulderclaysoilsisprese
tedTheissueofgeotech
icalcertificatio
israiseda
drecomme
datio
soutli
edo
itsmeritsfori
corporatio
withgrou
di
vestigatio
sa
dearthworks1INTRODUCTIONThei
vestigatio
a
dreuseevaluatio
ofma
yIrishboulderclaysoilsprese
tsdifficultiesforboththegeotech
icale
gi
eera
dtheroaddesig
e
gi
eerTheseglacialtillorboulderclaysoilsaremai
lyoflowplasticitya
dhaveparticlesizesra
gi
gfromclaytobouldersMostofourboulderclaysoilsco
tai
varyi
gproportio
sofsa
dgravelcobblesa
dbouldersi
aclayorsiltmatrixTheamou
toffi
esgover
stheirbehavioura
dthesiltco
te
tmakesitveryweathersusceptibleMoistureco
te
tsca
behighlyvariablera
gi
gfromaslowas7forthehardgreyblackDubli
boulderclayupto2025forMidla
dSouthWesta
dNorthWestlightgreyboulderclaydepositsTheabilityofboulderclaysoilstotakei
freewateriswellestablisheda
dpoorpla
i
gofearthworksofte
amplifiesthisThefi
esoilco
stitue
tsarege
erallyse
sitivetosmalli
creasesi
moistureco
te
twhichofte
leadtolossi
stre
gtha
dre
derthesoilsu
suitableforreusease
gi
eeri
gfillMa
yofourboulderclaysoilsespeciallythosewithi
termediatetypesiltsa
dfi
esa
dmatrixhavebee
rejectedattheselectio
stagebutgoodpla
i
gshowsthattheyca
i
factfulfilspecificatio
requireme
tsi
termsofcompactio
a
dstre
gthTheselectio
processshouldaimtomaximisetheuseoflocallyavailablesoilsa
dwithcarefulevaluatio
itispossibletouseori
corporatepoorormargi
alsoilswithi
fillareasa
demba
kme
tsFillmaterial
eedstobeplacedatamoistureco
te
tsuchthatitis
eithertoowettobestablea
dtrafficableortoodrytobeproperlycompactedHighmoistureco
te
tlowstre
gthboulderclaysoilsca
besuitableforuseasfilli
lowheightemba
kme
tsie2to25mbut
otsuitablefortrafficki
gbyearthworkpla
twithoutusi
gageotextileseparatora
dgra
ularfillcappi
glayerHe
ceitisvitalthattheearthworksco
tractorfullyu
dersta
dstheha
dli
gpropertiesofthesoilsasforma
yprojectsthisiseffectivelygover
edbythetrafficabilityofearthmovi
gequipme
t
f2TRADITIONALGROUNDINVESTIGATIONMETHODSForroadprojectsapri
cipalaimofthegrou
di
vestigatio
istoclassifythesuitabilityofthesoilsi
accorda
cewithTable61fromSeries600oftheNRAr