Soil Xploration
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SITE INVESTIGATION AND SOIL
EXPLORATION
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SITE INVESTIGATION
Site investigation is the process of acquiring
the atas of su! surface conitions for esign
of structures an p"anning constructiontechnique#
Inc"ues $
eter%ination of profi"e of soi" eposit&'o""ecting sa%p"es to eter%ine engg# Properties
In(situ testing of soi"#
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)*+ SITE INVESTIGATION,
To se"ect t-pe an epth of founation#
Deter%ine !earing capacit- of soi"#
Esti%ation of sett"e%ent
Location of G)T an .ater properties#
Lat# Pr# in a!ut%ent an retaining .a""#
Se"ect construction technique#
Preict an so"ve founation pro!"e%s# Ascertain suita!i"it- of soi" as construction %ateria"#
Investigate safet- of e/isting structure an suggest re%eia"
%easures#3
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*O),,
Re"evant in for%ations are o!taine !-Dri""ing ho"es
Ta0ing sa%p"es
Deter%ining ine/ properties an engg properties#
Insitu test(to fin properties of soi" in natura"
conition#
Prepare !ore"og#
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PLANNING S12S1R3A'E EXPLORATION
E/p"oration epens upon t-pe of structure to !e !ui"t#
E/tent of su! surface e/p"oration is c"ose"- re"ete to re"ative cost of
e/p"oration#
The %ore etai"e investigations are one& the %ore is 0no.n a!out su! surface
conition#
The e"e%ent of uncertainit- is reuce an greater econo%- is achieve in
construction#
The cost of e/p"oration varies !4. 5#56(5#78 of the entire constuction cost an
98 in certain cases
Ai% is to get %a/# infor%ation usefu" in esign an construction of the pro:ect
at %in# cost#
A s%a"" house !ui"t in an a"rea- eve"ope area .i"" require %uch "ess
investigation than one !ui"t in ne."- eve"ope are# 5
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STAGES IN S12S1R3A'E EXPLORATION
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RECONNAISSANCE
Genera" topograph- of site ; rainage& itches& sanitar- fi""s< E/istence of sett"e%ent crac0s in the structure a"rea- !ui"t near the site
The evience of "ans"ies& creep of s"opes an shrin0age crac0s
Stratification of soi"s as o!serve fro% eep cut near the site
Location of high f"oo %ar0s on near!- !ui"ings an !riges
Depth of G)T as o!serve in the .e""s
E/istence of springs s.a%ps etc##
Drainage pattern e/isting at site
T-pe of vegetation ;ientification of nature of soi"onta" an
vertica" irection
Governe !- epth of inf"uence >one
The epth upto .hich the stress incre%ent ue to superi%pose "oas can
prouce significant sett"e%ent an shear stress is ca""e as significant epth;S#D#onta"
irection
3or "ess i%portant !ui"ing 9 !ore ho"e at the centre
3or co%pact !ui"ings ;5#B hect# Appro/#< B at corners an 9at centre
3or "arge %u"ti store-e !ui"ings a"" corners an a"so at
i%portant "ocations
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>ETHODS OF EXPLORATION
Direct methods $ test pits& trenches& rifts an
shafts
Semi direct methods$ !orings
Indirect methods$ souning or penetration test
an geoph-sica" %ethos
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'ORIN
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A?
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*an operate augers
Po.er riven augers
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Auger !orings are use in soi"s .hich can stan open .ithout
casing
3or soi"s .hich can not stan unsupporte&for san- soi"s !e"o..ater ta!"e& !racings are nor%a""- require
It can not !e use .hen there are "arge co!!"es& !ou"ers or
other istur!ance
Suita!"e for high.a-s an rai".a- su!surface investigation.here the epth of e/p"oration is s%a""
Rapi an econo%ica"
Disavantages $
Soi" sa%p"es are high"- istur!e Difficu"t to "ocate e/act changes in soi" strata
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ROTAR@ DRILLINPLES
Soil sampling is the process of o!taining sa%p"es of soi" fro% the
esire epth at the esire "ocation in a natura" soi" eposit .ith a vie.
of assessing the engg# properties of the soi" for ensuring proper esign of
founation#
Depening upon the egree of istur!ance cause uring sa%p"esoperations& soi" sa%p"es are !roa"- c"assifie as$
Distur!e sa%p"es
Non representative sa%p"es
Representative sa%p"es
1nistur!e sa%p"es
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Disturbed samples:
The sa%p"es in .hich the natura" structure of the soi" gets part"- or fu""-
%oifie uring sa%p"ing
To et# Ine/ properties Non representative samples
It consist of %i/ture of %ateria"s fro% various soi" or roc0 strata or are
sa%p"es fro% .hich so%e %inera" constituents have !een "ost or %i/e up
Suita!"e on"- for proviing qua"itative infor%ation such as %a:or changes
in su! surface strata
Eg# Soi" sa%p"es fro% auger an .ash !oring
Representative samples
It contains a"" the %inera" constituents of soi" !ut the structure of soi" %a-
!e significant"- istur!e The .4c %a- a"so have change
The- are suita!"e for ientification an eter%ination of so%e ph-sica"
properties
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Undisturbed samples:
The sa%p"es in .hich natura" structure of the soi" an the .4c
are retaine
In these t-pe of sa%p"es the %ateria"s are su!:ecte to %in#
istur!ance so that the sa%p"es are suita!"e for strength test an
conso"iation test
So%e istur!ances are inevita!"e uring sa%p"ing even if
at%ost care is ta0en an thus pure"- unistur!e sa%p"es are
not o!taine
Eg# Tu!e sa%p"es an chun0 sa%p"es
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T@PES OF SA>PLERS
The soi" sa%p"ers are c"assifie in genera" as
Thick wall samplers
Sp"it spoon sa%p"ers
Thin wall samplers She"!- tu!e sa%p"ers
'"assification !ase on %oe of operation
Open rive sa%p"er
Stationar- piston sa%p"er Rotar- sa%p"er
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SPLIT SPOON SA>PLER
It is a co%%on"- use sa%p"er for o!taining istur!e sa%p"es ofthe soi"#
It %ain"- consists of
Driving shoe %ae of too" stee" a!out 6%% "ong
Stee" tu!e a!out B65%% "ong& sp"it "ongituina""- in t.o ha"ves 'oup"ing at the top of the tu!e a!out965%% "ong
Insie ia of sp"it tu!e (F%%& outsie ia(65%%
The sa%p"e is co""ecte !- :ac0ing or forcing the sa%p"er into the
soi" !- repeate !"o.s of a rop ha%%er#
The sa%p"er is then .ithra.n an ta0en out#
It is then p"ace in a container& sea"e an transporte to "a!orator-#
The sp"it tu!e is separate after re%oving the shoe an the coup"ing
an the sa%p"e is ta0en out#26
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INSIT? FIELD TESTS
The fo""o.ing are the %a:or fie" tests for eter%ining thesoi" strength$
9# Vane shear test ;VST
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STANDARD PENETRATION TEST
Cost co%%on"- use in(situ test esp# for cohesion"ess soi"
.hich can not !e easi"- sa%p"e#
The test is e/tre%e"- usefu" for
Deter%ination of re"ative ensit- an ang"e of shearing
resistance of cohesion"ess soi"s#
Deter%ination of unconfine co%pressive strength of
cohesive soi"s#
The SPT test is conucte in a !ore ho"e using a stanar sp"itspoon sa%p"er#
)hen the !ore ho"e has !een ri""e to the esire epth& the
ri""ing too"s are re%ove an sa%p"er is "o.ere to the !otto%
of the ho"e# 3
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The sa%p"er is riven into soi" !- a rop ha%%er of #60g %ass
fa""ing at a height of 65%% at the rate of 5 !"o.s per %inute#
The no$ of ha%%er !"o.s require to rive 965%% of the sa%p"e
is counte# The sa%p"er is further riven !- 965%% an the no$ of !"o.s is
recore#
This is again repeate one %ore ti%e#
The no$ of !"o.s recore for the "ast t.o 965%% interva"s are
ae to give the stanar penetration nu%!er#;N