soil xploration

7/25/2019 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

soil xploration

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