Introduction of Site Investigation

8/13/2019 Introduction of Site Investigation

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Site Investigation for CivilEngineering Projects

By Ir. Neoh Cheng Aik

E-Geo Consultant Sdn Bhd


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SCOPE OF DISCUSSION

1. INTRODUCTION General

What is SI

Role of SI in Geotechnical Design

2. WORK PROCEDURE FOR SI

3. PLANNING SCOPE OF SI

What needs to be known

SI Methods Criteria to determine depth core length

Examples

4. INTERPRETATION

Field & reported borelogs

Property correlations

Groundwater

Miscellaneous5. CONCLUSIONS


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GENERAL

1. Geotechnical Engineering (3 major areas) Geotechnical Engineering is a science, but its practice is an art

SI & soil properties (Significance?)

Basic, index & chemical properties

Engineering properties

Typical properties of typical formations

Planning of SI & methods

Soil Mechanics Principles Applications Design & Construction

2. Difference between geotechnical & structural design

3. Learning curve (easy to learn & slow to master)4. Inadequate SI & poor interpretation main causes for

failure? Examples? Liabilities?


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WHAT IS SI?

Scientific exploration with predeterminedobjectives

Know something first through desk studies &

site visit about the site & project before we can

determine the purpose of SI & identify the

possible geotechnical problems

Subsequently, we plan scope of SI to obtain the

necessary parameters to verify, assess &

quantify the geotechnical problems identified Prerequisites to qualify to plan SI?


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WHAT NEEDS TO BE KNOWN?

What is known; what is not known; & what needs tobe known?

?

?

?

?

?

?

?

?

What is not known

about the site

Circle of what is known

What needs to

be known

Circle of

KNOW ALL

* Those who know NUT and know not that they know NUT will

not know what Needs to be known.


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EXTENT & SCOPE OF SI REQUIRED

FOR A PROJECT DEPEND ON: Experience & knowledge of designer about

the anticipated geotechnical problems, the

project brief & available SI facilities &

methods

Local geology & typical problems Historical use of the site: Why significant?

Treacherous Grounds: uncontrolled fill,

limestone formation, boulders & corestone

abutment ground, etc. (significance?)

Relevant information about the project, etc.


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EXAMPLE 1:A 4-Storey JKR Standard RC School Block in

Klang District

Do you know the column loads & characters

of RC framed structures?

Do you know the site & layout

conditions/constraints? Do you know the site geology & typical

geotechnical problems?

Do you know what parameters are required?

Do you know what SI methods & tests to

procure the required parameters


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EXAMPLE 2:

A hill is to be cut to a depth of about 24m

SCOPE OF SI?

Answer 3 questions: what known; what unknown &

what needs to be known?

Influencing factors affecting FOS?

Geological information of the hill?

Weathering profile (discontinuities, relict joint,

suitable minerals, shear strength & deformation,

permeability)

Groundwater conditions?

Other critical information?


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PLANNING SCOPE OF SI

How many BH or other SI methods; locations?

Criteria of terminating BH?

Field test: type, criteria & frequency? Sampling: type, criteria & frequency?

Reference notes: for building & road projects

Documentation: Drawings, BQ, Spec, etc.

Examples


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BASIC SCOPE OF SI WORKS

SI

DESK

STUDIES

& SITE

VISIT

BORING SAMPLING FIELD

TESTING

LAB.

TESTING

PURPOSE & IMPORTANCE OF EACH ACTIVITY?


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BORING

TYPES OF BORING: Auger boring

Percussion Wash boring

Rotary boring

Foam drilling SPECIFICATIONS & STANDARDS

Tools & equipments; flushing medium?

PURPOSE, APPLICATIONS &LIMITATIONS?


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SAMPLING

DISTURBED

SAMPLES

WASH

SPT

BULK

UNDISTURBED

SAMPLES

CONTINUOUS

SAMPLES

WATER

SAMPLES

ROCKSAMPLES

THIN-WALL

PISTON

MAZIER

BLOCK

FROZEN

PURPOSE, APPLICATIONS & LIMITATIONS?


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COMMON SAMPLERS

TYPE OF SAMPLERS (Purposes?)1. Open drive samplers

Split-spoon for SPT

Thin-wall sampler

Thick wall sampler(50mm, 75mm, 100mm, 150mm)

2. Thin-wall sampler with stationary piston

(50mm, 75mm, 100mm, 150mm)

3. Denison Sampler

(double tube with thin-wall tube)

4. Mazier Sampler (74mm)

5. FOIL CONTINUOUS SAMPLERS

6. BLOCK SAMPLING

7. ROTARY ROCK CORE SAMPLERS


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FIELD TESTING

SPT

VANE SHEAR

PACKER

PERMEABILITY

PRESSUREMETER

DUTCH CONE

PIEZOCONE

MACKINTOSH

PROBE

JKR PROBE

TEST PIT

CBR

PLATE BEARING

FIELD DENSITY

GEO PHYSICAL

SURVEYS SPECIAL TESTS

SPEC. & STANDARD

PURPOSE, APPLICATION

& LIMITATION?


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FIELD TESTS Soil Soil Rock SOIL TYPE SOIL PARAMETERS

type Profile H.Rock S.Rock Gr Sand Silt Clay Peat Cu Mv Cv K

1. Penetrometer

1.1 JKR Probe

1.2 SPT

1.3 DS (CPT)

1.4 Piezocone (CPTU)

1.5 Flat Dilatometer

1.6 Resistivity Probe

X

A

B

A

B

C

C

B

A

A

A

C

X

X

X

X

X

X

X

B

X

X

X

X

C

B

B

A

C

C

B

A

A

A

A

A

B

A

A

A

A

A

B

A

A

A

A

A

B

A

A

A

A

A

X

B

C

B

B

B

B

B

B

B

B

C

X

X

C

A

C

X

X

X

C

A

C

X

X

X

X

B

X

X

2

3

4

5.

Vane Shear

PB Pressuremeter

SB Pressuremeter

Continuous Soil Sampling

B

B

B

A

C

B

B

A

X

C

C

X

X

A

B

B

X

B

B

B

X

B

B

A

B

B

B

A

A

A

A

A

B

B

B

A

X

X

B

C

A

B

B

B

X

B

B

B

X

C

B

B

X

X

B

C

Legends:-

A = suitable/useful

= effective frictional angle K = coef. Of permeabilityB = moderate Cu = undrained strength

C = doubtful Mv = coef. of volume compressibility

X = not suitable Cv = coef. of consolidation

APPLICABILITY OF COMMON FIELD OR INSITU TESTS


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LABPRATORY TESTING

BASIC INDEX

PROPERTIES

SHEAR

STRENGTH

OTHER

TESTS

UU, CIU, CD

Shear box

Compressibility Compaction

CBR

CHEMICAL

PROPERTIES

Organic, SO3-

& Cl-

PH value, etc.

1-D Oedometer

Rowe cell

Compaction Permeability

Dispersibility

Hydraulic cell

PURPOSE, APPLICATIONS & LIMITATIONS?

Colour, S.G.,

density, LL,

PL, PI, SL,

PSD, etc.


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ROLE OF SI IN GEOTECHNICAL ENGINEERING DESIGN

SISOIL

PROPERTIES

GROUND

CHARACTERISATION

GROUNDBEHAVIOUR

ENGINEERING

PERFORMANCE

ENGINEERING PROPERTIES

CHEMICAL PROPERTIES

BASIC & INDEX PROPERTIES

MASS PROPERTIES

TYPICAL & GENERALISED SUBSOIL

PROFILE & PROPERTIES OF TYPICAL

GEOLOGICAL FORMATIONS; MAN-MADE FILL, etc.

ENGINEERING GEOLOGY

SOIL & ROCK MECHANICS

EFFECTIVE STRESS THEORY SEEPAGE THEORY

STRESS DISTRIBUTION

LATERAL PRESSURE

BEARING CAPACITY

COMPRESSIBILITY

COMPACTION, etc.

INSTRUMENTATION FOR

PORE WATER PRESSURE

EARTH PRESSURE

DISPLACEMENT (SURFACE &

SUBSURFACE)

INTERNAL STRESSES

VIBRATION

CODES OF PRACTICE

FOUNDATIONS, BS 8004

ANCHORS, BS 8081

EARTHWORKS, BS6031

REINFORCED FILLS, BS 8006

GEOGUIDES OF GEO HONG

KONG

GROUND IMPROVEMENT

DEFORMATION

DISPLACEMENT

STABILITY

MODELLING

PREDICT

ION

INTERPRETATION

JUDGEMENT


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GROUNDWATER MEASUREMENT

1. TYPES OF GROUNDWATER Static WT/phreatic level/main

WT

Perched WT

Artesian water

2. SIGNIFICANCE FOR

Pile installation

Deep excavation

Slope stability

Tunnelling, etc.

3. METHODS

Observation well Simple Standpipe

Casagrande standpipe

Pneumatic piezometer

Hydraulic piezometer, etc.4. CASE HISTORIES


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ARTESIAN WATER

FREE WATER SURFACE

MEASURED WT

ACQUICLUDE

AQUIFIER

RAIN

STREAM

(FREE WATER)

UNCONFINED AQUIFIER

AQUICLUDE

ACQUICLUDE

PERCED WT

LEGEND:

RUNOFF

INFILTRATION

PERCOLATION


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APPLICATION OF GEOTECHNICAL INSTRUMENTATION

13

101

3

4

6

5

15

2

9

8

6

15

15

1

2

3 Electrical piezometers

Stress gauges

Inclinometer casings

Casagrande piezometers4

In-place inclinometers5

Load cells6

Flow meters7

Surface clinometers8

9 Borehole extensometers

10 Wire crackmeters

13 Rain gauges

15 Total pressure cells

Monitoring of earth lateral movements in sliding areas

Measurements of soil stress and pressure on ground or retaining walls or piles

Drainage flow control

Measurement of anchor tensioning or loading at the head of tie-back

Monitoring of landslide areas and stability of natural slopes

Measurement of water table level

Monitoring strain and stress development in the stressed member of piles

Monitoring of soi l pore pressure and control of over pressure

Monitoring cracks and movements in rock masses

Monitoring of rain falls

Monitoring of retaining wall stability

Moni tor ing of rock mass inclina tion movements and block tilting

ApplicationInstrumentation


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SPT1. SPEC. & STD. (BS, ASTM)

Equipment set

Hammer, drop, rod

Split spoon sampler

Records & procedure

2. APPLICATIONS & LIMITATIONS

Soil types

Correlations

Shortfalls

3. SPACING/INTERVALS OF TESTING Type of investigation & purposes

Criteria & procedure

4. CASE HISTORIES


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COMMON MALPRACTICE IN SPT/SI

* SPT taken without adequate & proper cleaning by clean water

* SPT taken constantly at 1.5m intervals; not at change of soil strata

* SPT hammer weight not within 63.5+_ 0.5 kg; hammer not fully made of steel;drop height less than 76+_ 2 cm after repair/retread.

* Drilling in sandy soils without quality bentonite

* Use casing and not proper drilling rods to advance boreholes

* Samples from SPT split sampler not sealed in container with proper labels &storage

* Use blunt SPT drive shoe

* Mark SPT penetration on rod without ruler or chalk

* Soil description & record of SPT blow counts on palm/shirt/casing & not proper

paper *Drive rod for SPT not straight or inadequate stiffness; for depth>20m, BWNW

rods shall be used

* Untrained supervisor or foreigner supervisor who cannot communicate well


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ROCK CORING

1. PURPOSE & APPLICATIONS:

Identification, description & correlations

2. CORE BARREL: single, double & triple

3. CORE BITS: tungsten, surface/impregnated diamond

4. CORE RECOVERY RATIO, RR = (Total core obtained)/(length of run)

5. RQD = (summation of rock core > 100mm)/(length of run)

RQD < 25% VERY POOR

RQD = 25 50% FAIR RQD = 50 75% GOOD

RQD = 75 100% EXCELLENT

6. ROCK DESCRIPTION: STRENGTH & WEATHERING GRADE

UCS < 5 N/mm2 Weak

UCS = 5 12.5 N/mm2 Moderately Weak

UCS = 12.5 50 N/mm2 Moderately Strong

UCS = 50 100 N/mm2 Strong

UCS = > 100 N/mm2 Very Strong


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A & B

ZONES

VI

V

IV

III

II

I

1. Implication of Location of WT

& slope stability2. Usual location of groundwater

3. Discontinuities & relict joints

4. What relevant soil/rock

properties (tests) are necessary

for slope stability analysis?


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Weathered granite showing well defined relict jointing


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Weathered volcanic rock showing well defined relict jointing


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Granite showing intense weathering along joints


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Volcanic rock with staining along joints: Zone D


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Completely decomposed seam (Grade V) in slightly decomposedvolcanic rock (Grade II)


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Moderately decomposed seam (Grade III) in slightly decomposedvolcanic rock (Grade II)


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Moderately decomposed granite rock (Grade III), 4.65 to 5.55 mHighly decomposed granite rock (Grade IV), 5.55 to 10.71 m


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Moderately decomposed granite rock (Grade III), 21.48 to 22.00 mSlightly decomposed granite rock (Grade II), 22.00 to 24.48 m


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Purpose & significance Field & lab. techniques

BS5930 description of soil

Consistency or relative density, fabric if

distinguishable, colour, subsidiary, grading, principal

soil type & more detailed comments

e.g. very stiff dark grey silty CLAY with traces of sand

e.g. sandy silty CLAY

e.g. silty sandy CLAY (Wrong!)

SOIL IDENTIFICATION & DESCRIPTION


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SOIL CLASSIFICATION

BSCS, USCS, AASHTO

Based on grading & index properties

Coarse grained soil = PSD; fine grained soil =plasticity; How & what properties are

influenced by moisture?

Purposes & application?

Design guides based on soil classification


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SI RESULTS INTERPRETATIONS

Scope of factual report: JKR Spec.

Scope of interpretation report

Field & reported borelog Check borelogs & summary of lab. Test results

Discrepancies/compliance with Std/Spec

Interpretations: Atterberg limits, compaction test, etc.

Typical geological formations; typical geotechnical

problems to various types of foundations, etc.


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JOB NO PE/SI/21/93 BOREHOLE B6PROJECT S b f I i i d T i f P d W P (Ph II) P l L P Kl


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DEPTH(m)

TESTING

SAMPLINGCORING

5

7

6

4

3

2

1

P2/D4

(Rods Weight)

R=35/45cm

UP2/D3

R=66/80cm

UP1/D1R=80/80cm

DESCRIPTION OF MATERIAL

Very SoftGrey fine sandy silty CLAY wi th tracesof shell fragment and thin layers oforganic matter

Very Soft

Grey silty CLAY wi th trace of fine sand,

shell fragment and organic matter

SYMBOL

CONTENT

(%)

CHLORIDE

CONTENT

(%)

SULPHATE

CONTENT

(%)

ORGANIC

PHVALUE

COMPRESSION

UNCON

FINED

GRAVITY

SPEC

IFIC

(Mg/m

)

BULKDENSITY

CLASSIFICATION

SO

IL

CONSOLIDATIONTEST TEST

CHEMICALTRIAXIALTESTDISTRIBUTION

PARTICLE SIZE

GRAVEL

(%)

(%)

SAND

(%)

SILT

(%)

CLAY

STRENGTH(kPa

)

3

(kPa)

C

() (kPa)

P C eC C O

ATTERBERG LIMITS

MCPL LL

20 40 60 80 100

(%)

10 20 30 40 50SPT N

P1/D2(Rods Weight)R=30/45cm

Very SoftGrey very clayey fine SAND wi thsome shell fragment and trace oforganic matter

Very Soft becoming soft

Grey s ilty CLAY with lenses of fine sand

and organic matter; with occassional

shell fragment between 5 .0m - 9.0m

8

9

10

UP3/D5

R=80/80cm

P3/D6

(Hammer

Weight)

R=37/45cm

UP4/D7

R=65/80cm

P4/D8

(Hammer

Weight)

R=29/45cm

UP5/D9

R=78/80cm

P5/D10

(Hammer

Weight)

R=25/45cm

WATER LEVEL:

REDUCED LEVEL:

TYPE OF BORING:

JOB NO: PE/SI/21/93

Seabed Level (ACD) - 14.50m

Rotary

Depth of water 16.70m a.s.l.# (19/12/92)

BOREHOLE: B6

LOCATION: Pulau Lumut, Port K lang

17/12/92 - 19/12/92DATE DRILLED:

CLIENT:

CONSULTANT:

Lembaga Pelabuhan Klang

Sepakat Setia Perunding

PROJECT: Subsurface Investigation and Testing for Proposed West Port (Phase II) Pulau Lumut, Post Klang

0 50 24 26 CHS 0.42515 1.472

110 3554 CI 1.557 27.39 23 0

60 4945 1.565CE 19.312.12 1.4701.089160

1.492CI 31.03 31 0

50 5045 1.568CE 83.28 0.778180 1.494

SOILS SYMBOL P=STANDARD PENETRATION TEST

CR=CORE RECOVERYC=CORING

V=VANE SHEAR TEST

UP=UNDISTURBED SAMPLE

D=DISTURBED SAMPLE

N=NO. OF BLOW PER 30cm UNDISTURBED

REMOULDED

VANE SHEAR:REMARKS:

1. R - - Denotes Recovery

# -- above seabed level2.

ENGINEERINGBORELOG

SIGNIFICANCE OF ATTERBERG LIMITS


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SIGNIFICANCE OF ATTERBERG LIMITS

Shrinkage

limit WS

Plastic

limit WP

Liquid

limit WL

Plasticity

Moisture, MC

WL & WP = f(amount & type of clay)

PI = f(clay content)

High PI = high clay content

PI < 30% = sandy/silty soils

Soils of high PI cant be stabilized unless MC is

dissipated, very slow due to low K


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-

-

1.0

CI

0

0.25

0.75

0.5

WS W WP N

LW=CI

WL

V. SOFT

SOFT

FIRM

STIFF

WL

20 - 40

< 20

75 - 100

40 - 75

CONSISTENCY

HARD

V. STIFF

WP

WN C (kN/m )

> 200

100 - 200

U2

WP

WS

VS VA

COMPACTION TESTS


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COMPACTION TESTS

Purposes & applications

Interpretation & appreciation

1.6

1.7

1.8

1.9

2.0

2.1

2.2

2.3

0 2 4 6 8 10 12 14 16 18 20 22

Water content (%)

Dry

dens

ity

(Mg/m

)3

10% 5% 0%Air content

Saturation line

4.5 kg rammer

2.5 kg rammer

1.6

1.7

0

Water content (%)

Dry

dens

ity

(Mg/m

)3

2.1

1.8

1.9

2.0

2.2

5%Air content10% 0%

30

1.4

1.5

5 10 15 20 25

GW

SW

ML

CL

CH


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Soa

ke

dCBR

Moisture content

Moisture content

Dry

dens

ity

Soil A

Soil B

Soil C

Z.A.V.

Soil A

Soil B

Soil C

OTHER INTERPRETATIONS


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OTHER INTERPRETATIONS

SG = 2.6 2.7, usually

Soils with SG < 2.6, soil type?

Soils with SG > 2.7, soil type?

PI < 30%, soil type?

Activity, A = PI/(% of clay)

Kaolinite, A = 0.3 0.5

Illite, A = 0.9

Montmorillonite, A > 1.5 Soils with high A can absorb more water; more swelling

& shrinkage problems; applications?

TYPICAL GEOLOGICAL FORMATION & TYPICAL


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TYPICAL GEOLOGICAL FORMATION & TYPICAL

PROPERTIES

1. Residual soils of granite:

% of sand/gravel is high

WL < 60 %, PI < 30% generally

Density = 18 20 kN/m3 , NMC = 10 30%

C = 0 20 kPa, = 30 42

Weathering profile & boulder problems

dmax = 15 20 kN/m3, OMC = 10 18% (Std. Comp.).

Relict joints are preferred water path; have lower shearstrength; Significance? How to identify?

Common Geo Problems to piling, deep excavation, slopes?

Important properties sought in SI?


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2. Residual Soil of Meta Sedimentary Rocks:

Generally WL < 80 %, PI < 40%

Density = 16 22 kN/m3

C = 0 25 kPa, = 25 38

dmax = 15 19 kN/m3, OMC = 12 24% (Std. Comp.)

Relict discontinuities/beddings/foliations are preferredwater path; have lower shear strength; significance? How

to identify?

Common Geo Problems to piling, deep excavation, slopes?

Important properties sought in SI?


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3. Soft Alluvial Clay:

Generally WL = 40 140%

PI = 20 90%, NMC = 40 130%

Sensitivity = 2.5 8, OCR = 1 4 (


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CONCLUSION

SI is part of Geotechnical Design. Why?

Scope & definition of Proper SI: properly planned, supervised,

monitored, directed & reported

Important to understand & to identify possible geo problems of the

ground to the project before planning scope of SI

Important to learn typical subsoil profiles for various typical geological

formations/grounds, their typical properties and their usual problems to

various types of construction

SI soil properties Mass properties & ground characterization

Behaviour prediction Performance

Scope of SI planned by different engineers tends to be varied. Why?


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The End

Thank you for your attention

Documents

Introduction of Site Investigation