Chapter 1 Exploration

8/17/2019 Chapter 1 Exploration

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05/11/16 Planning 1

Site Exploration Purpose: Identifcation o stratifcation

and important engineering properties Strength, deormation and hdraulic

Inormation needed: or decision on

oundation tpe, !earing capacit,

settlement estimation, identifcation oen"ironmental pro!lem and pertinentsolution#



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%ote Allowance must be given for possible

design changes as excavation for

construction could reveal newconditions that were not evident duringexploration phase.



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Planning an Exploration

Program Planning: 'aximi(e inormation and minimi(e

cost) International practice sho*s soil exploration can cost

0#5 to 1+ o total proect cost# - conser"ati"e design tending to sa"e on exploration

cost does not guarantee saet and e"en econom#

Erratic soil does not necessaril impl need or

extensi"e !oring# .he aim in this case should !eesta!lishment o general picture o stratifcation*ith conser"ati"e design ultimatel#

'aximi(e se o -"aila!le inormation



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Steps in a Soil Exploration

Program -ssem!l o inormation: on tentati"e laout,

unction, special eatures, etc# .his ma in"ol"econsulting dierent maps and preliminardra*ings

2econnaissance/-ppraisal: *al3 o"er site tore"eal crac3s, sags, stic3ing doors 4 *indo*s,etc# tpe o existing structures gull trenchesroc3 outcrops an other rele"ant ino#

Preliminar In"estigation: e* !orings toesta!lish general ormation one or a e* deep!oreholes to competent strata i upper soil isloose



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Steps in data should su7ce or preliminar design 4

identifcation o construction method 8sheeting,diaphragm *all, pile *all, tie!ac3s, etc#9 suita!ilit

o site 4 econom esta!lished# etailed In"estigation: Purpose is to refne

design and decide on an special constructionmethod in"estigation extent depends on

preliminar data generall, it in"ol"es morein"estigation *ith one or more !oreholes tocompetent roc3#



Exploration 'ethods epending on the unction, si(e, and

importance o the structure, one or

more o the ollo*ing explorationmethods can !e emploed ;pening test pits and/or trenches

Sin3ing !oreholes <eophsical in"estigation <eological in"estigation

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.est Pit and .renches -d"antages

=heap,

ast,

ena!le direct "isual inspection

<ood samples can !e extracted

isad"antages Shallo* in"estigation

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@oring 'ethods @oring has t*o phases: -d"ancing hole

4 sampling#

'an techniAues a"aila!le: ependanton material encountered and purpose# -d"ancing techniAues: -ugering, *ash !oring

, percussion drilling, rotar drilling, continuoussampling, displacement method, etc#

Sampling techniAues: Spiral, !uc3et, hollo*Bstem augers, solidB and splitBspoon samplers, Shel!Btu!e 8thin *all9, stationar piston, singleB and dou!letu!e roc3 core !arrels#


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@oring 'ethods .*o 'aor Pro!lems: =a"ing o *all 4

hea"ing o !ottom#

Dea"ing: occurs in all holes due to stressrelease serious !elo* <. due to seepage useo drilling Fuid maintained a!o"e <. helps#

=a"ing: serious in cohesionless deposits and

!elo* <. also in ointed roc3 !elo* <.depending on degree o *eathering at the ointsthus, use o casings or dri"e pipes !elo* <. iscommon#


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-ugering Dand -ugers: 8a9 Ship or helical 8!9 closed spiral

8c9 open spiral 8d9 I*an or postBhole auger#


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-ugering Po*er -ugers %eed po*er or rotation 4 pressure

Garing si(e and capacit in t*o maor

categories: Fight augers 85 to 1$0cm Φ9 4!uc3etBtpe augers 8&0 to $0cm Φ9#

@uc3etBtpe augers: ;pen top slotted 4 teethed!ottom the !ig si(es can accommodate an inspector#

Hlight augers: SingleBFight, dou!leBFight, high spiral,

con"eorB or continuousBFight, and hollo*Bstemaugers attaching additional height o spiral in thesingleB and dou!leBFight augers is common to sa"e

time


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-ugering =on"eorBFight auger: eep penetration can !e

attained up to &0m 'ixing up o material is adisad"antage#

Dollo*Bstem augers: Internal diameter ranges!et*een >cm and 16 cm consists o a steel tu!e*ith spiral !lades also suita!le or loose deposits!elo* <. center stem and plug replaced !sampler during sampling tu!e ser"es as casing

high Aualit samples can !e retrie"ed SP. can !econducted#



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-ugering Po*er -ugers:

Penetration & to >m

a9 singleBFight earthauger

!9 dou!le Fight earthBroc3auger

c9 dou!leBFight roc3

augerd9 high spiral auger



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-ugering Po*er -ugers

Penetration at

least &0m 8up to100m9

a9 =on"eor Fight auger

!9 @uc3et auger

c9 Dollo*Bstem auger



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-ugering .pical truc3Bmountedauger rig




ash @oring Starts ! dri"ing a casing o $ to &#5m length#

=asing is cleaned ! chopping !it and

pressuri(ed *ater# 2aising, rotating 4 dropping o !it is necessar#

Is *idel emploed in S# -merica, -rica 4-sia#

@it is replaced ! sampler during sampling#



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ash @oring 8schematic9 Schematic representation



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Percussion rilling =ommon in drilling *ater *ells#

In"ol"es alternate raising 4 dropping o hea"

drilling tools, pouring o *ater and periodical!ailing or pumping o slurr tpe o !itdepends on material encountered#

-d"antageous in coarse granular deposits *ith!oulders and in ca"ernous limestone#

- maor disad"antage: the hea" !lo*s candistur! soil to a signifcant depth di7cult todetect thin laers#



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Percussion .ruc3B

mountedPercussion

drilling rig



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2otar rilling ses rotation 4 pressure or ad"ancement#

'ost rapid in less fssured roc3s#

@entonite mud/slurr or casing necessar ica"ing is a pro!lem#

Garious drill heads ma !e emploed: augerheads grinding heads coring !its etc




2otar rilling

- hdraulicBeed rotar drilling rig



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2otar rilling

2otardrilling

!its

a9 Hishtail

!9 Da*thorn

c9 =ar!ide

d9 .ricone

e9 iamond



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Samples 4 Sampling .*o tpes o samples

istur!ed !ut representati"e:

Structure could !e lost !ut should contain allconstituents in proper proportion Emploed or identifcation, *ater content,

compaction tests and locating !orro* materials#

Jndistur!edK Digh care exercised to preser"e structure -rea ratio ma not exceed 1&+



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Samples -rea ratio, -r:

%1002

22

×−=i

ior A

φ φ φ

φo is outerdiameter

φi is inner diameter




Samplers Split-barrel (split-spoon) sampler 'ost commonl emploed or distur!ed/

representati"e samples

φiL &? to 115mm in 1$#5mm incrementsML5 and 60cm tL6#mm#

.he φiL &?mm !arrel is popular !ecause o

existing correlations !et*een % and soil

properties) Hor minor structures, design is commonl

made on the !asis o data rom such samples

- num!er o inserts or soil retention are u




Samplers .pical splitB!arrel

sampler andsample retainers



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Thin-wall (Shelby)tube sampler 'ost commonl used

tL1#5 to &#$mm φ L 50and >5mm M L 60 and>6cm

se o φ L 100 and150mm is no*adasspecifed ! someauthorities# -d"#: Itena!les to cut out oursamples or triaxial test)

Samplers 8undistur!ed9



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Samplers### Thin-wall (Shelby)…

φi o cutter: 0#5 to 1#5+ o φi o tu!e#

rust protection on the internal *all isnecessar i tu!e is steel# sed in sot to sti cohesi"e soils#

ri"ing emploed in hard cohesi"esoil#

pon retrie"al, a!out $#5cm o thesoil on !oth ends is remo"ed andplaced in a tight ar or moisturecontent and other tests#



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Samplers### Piston Samplers

Thin-wall stationaryPiston Sampler 2etention is ! creating "acuum =onsists o a thinB*all tu!e

sampler, a piston, a 1$#5mm

piston rod and a modifedsampler head#

φi L &5 to 1$5mm M L &5 to

>5cm most common: φi L

>&mm *ith M L >5 cm thatretrie"es a sample 60cm long#



05/11/16 Planning &0

Samplers### Thin-wall stationary piston…

sed in sot to sti cohesi"e soil

Procedure: Sampler *ith piston lo*ered Piston rod is fxed and tu!e pushed 8ne"er

dri"en9 at >#5 to 15 cm/s#

Excellent Aualit o sample can !eo!tained

- *ide "ariet o this is a"aila!le




Samplers### Osterberg (double) piston samplers

'odifcation o Shel! *ith additional

actuating piston and a pressure clinder Sampling done ! pressuri(ed *ater on top

o the actuating piston orcing this and thesampler past the stationar piston

Sampler assem!l is pulled out *hen thet*o pistons come in contact



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Samplers### Osterberg (double) piston … Schematic



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Samplers### Swedish Foil samplers

;!ecti"e: to increase sample length per operation# Sample length up to $5m in one go is possi!le))

ltimate goal: to sample o"er!urden to frm laer in one go# Principle: entire elimination o sliding resistance# Equipment consists o sampler head, series o

!arrels and a loosel ftting Foating piston attachedto a rod or chain extending to surace# Sampler head: has tapered !ottom *ith sharp cutting

edge and a dou!leB*all upper section housing !" rolls ometal oils o t # $%$& or $%!&mm attached to the piston#



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Samplers### Swedish Foil%%%

EAuipment

'arrels: ML$#5m and φi L 6? interconnected !special longitudinall split coupling that reducedistur!ance during its remo"al

Procedure: Sampler *ith piston loc3ed to !arrel !ottom is

lo*ered# Piston is reed rom !arrel, !ut the rod to *hich it

is attached is loc3ed to drilling rig to 3eep pistonat one le"el throughout operation#




Samplers### Swedish Foil%%%

Procedure .he strips o oils un*ind en"eloping the entering

sample as the remainder o the sampler is pushed# -dditional !arrels are added as needed# pon completion, sampler is pulled out# -s a !arrel

emerges it is uncoupled rom the lo*er one exposing asmall section o oil co"ered sample# Hoils are cut,

!arrel capped and the exposed part retrie"ed in a ar# sed primaril in sot cohesi"e soils and uniAuel

adapted or thinl stratifed and "er sot soils#




Samplers### Swedish Foil…



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Sounding .ests B

Standard Penetration .est <eneral

e"eloped around 1C$>

Standardi(ed in -S.' since 1C5? 8as -S.'15?69

;riginall de"eloped or sand !ut used or allsoils presentl

Principle: resistance is proportional to soundness

=on"ention: SP. e"er 1 to $m starting roma!out 1#5m !elo* ground surace

Ena!les a!out 50+ sample reco"er#



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SP.### Schematic

representatio

n o threecommonlused SP.hammers

Asrat:

Asrat:



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SP.### Procedure

Standard split !arrel 85cm long9 dri"en !

hammer: mL6&#53g and ree allL>6cm @lo*s needed or e"er 15cm penetration

recorded

.otal !lo* count or the last $x15cm is %B"alue

.est is stopped i 50 !lo*s could not sin3 an 15cm increment 100 !lo*s could not sin3 last &0cm increment 10 !lo*s produce no ad"ance at all

Asrat:

Note that earlier to about 1967, N-value was the count

for the 1st 30cm-penetration, which could nearly mean a

50 reduction from the present standard! "nfortunately,

many #$% correlations in current use are based on this

earlier procedure!

Note that earlier to about 1967, N-value was the count

for the 1st 30cm-penetration, which could nearly mean a

50 reduction from the present standard! "nfortunately,

many #$% correlations in current use are based on this

earlier procedure!



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SP.### Inherent pro!lems

'isleading !lo* count can arise rom *arped sampler encountering !oulders Auic3 condition !elo* <.

ith proper attention paid, ho*e"er,these pro!lems can !e o"ercome#



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SP.### -dustments

%B"alues are not reproduci!le in

adacent !oreholes and ! dierenteAuipment mainl due to energ loss Input energ is constant:

E Whkg m s m J

in == × × =63 5 9 81 0 76 475

2. . .



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SP.### Eecti"e energ "aries !et*een &0 to

100+ o Ein

Possi!le sources or the energ loss: ierence in manuacturer

Dammer confguration

se o liner

;"er!urden eect

@orehole si(e

2od length



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SP.### efning energ ratio ound thus

important:

@lo* counts rom an eAuipment can

no* !e standardi(ed to a selected Er ,sa Erb so that a soil is characteri(ed

! a uniAue %B"alue#

E E E r a in= × 100%



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SP.### Galues o Er! suggested in the past:

50 to 55+ ! Schmertmann 81C>C9

60+ ! Seed et al 81C?59 S3empton 81C?69 >0 to ?0 + ! 2iggs 81C?69

>0+ ! @o*les 81CC69

@ased on @o*les suggestion, thestandardi(ed %B"alue !ecomesthen ′ = × × × × × N C N N 70 1 2 3 4η η η η



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SP.### .he correction actors η1, η$, η&, η, are

or energ, rod length, liner, and

!orehole si(e, respecti"el 8a"aila!le in@o*les 81CC69#

.he adustment or eecti"eo"er!urden is

%ote that

C p kPa N = ′9576 0. ( )

E E r r 1 2=



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SP.### ηi L1 or ErL>0+, lrN 10m, no liner and

φ!h ≤1$0mm

esign -*alues: Earl Practice: .he smallest or the a"erage

in a stratum

=urrent Practice: *eighted a"erage

N N Z Z av i i i= ∑ ∑



05/11/16 Planning ?

SP.### Oi is depth o increment

Hor ooting, a"eraging is done o"er the

inFuence (one 8 I#e#, rom @/$ to $@ !elo*ooting !ase9

+orrelations: %B"alues ha"e !een correlated *ith γ ,r,

φ, Au, Ault and Es# se o correlations on recent adusted %B

"alues is recommended 8see @o*les 81CC699#



05/11/16 Planning C

=one Penetration .est

8=P.9 <eneral

e"eloped in Dolland

Standardi(ed in -S.' 8as -S.' &19 @ecoming amous or sot clas, sot silts and

fne to medium sand deposits 8common in deepdeposits o Food plains, ri"er deltas 4 coastlines9

EAuipment consists o 60 cone *ith -!L10cm$ 8or Ac9

.apered slee"e 8to separate s3in riction9

Qac3et 8or As9




=P.### .pes

,echanical or utch +one Electric Friction 81st modifcation9: emplos

strain gauges or simultaneous measurement oAc and As#

Electric Pieo./riction: measures Ac, As, and u#

Seismic cone: ses "i!ration sensor to recordsismic *a"es rom generated rom hammerimpact at the surace# It ena!les to compute <s

and Gs#




=P.### .pical

mechanical andelectric

conepenetrometers



05/11/16 Planning 5$

=P.### Procedure: utch =one

=one alone is pushed at 10 to $0mm/s and

Ac measured .hen ac3et alone is pushed and As

measured

Hinall, !oth cone and ac3et are pushed

and Atot measured:( )

q q q

f q q

tot c s

r s a

= +

= × 100%



05/11/16 Planning 5&

=P.

.pical output



05/11/16 Planning 5

=P.###

Procedure: Electric Hriction in"ol"es continuous push 8no startBstop9

Ac and As recorded electronicall through nonnections

to strain gauges and plotted

-d"antages: Hast, especiall *ith E- sstem

-llo* continuous recording

seul in "#sot soils

allo*s correlations as is the case *ith SP.

Shortcomings Inapplica!le in dense and sti soils

Interpretation demands good experience



=P.### =lassifcation

chart !ased

on =P. results

Documents

Chapter 1 Exploration