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INVESTIGATION METHOD

By : Ahmad Muzakkir @ Khairom Muzakkir bin Baharom

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4 stages of investigation

1) Desk Study

2) Site Visit and Visual Assessment

3) Detail examination/ Special studies

4) Ground Investigation

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Desk Study

Every site investigation should begin with deskstudy.

Purpose : To find information about the site from:

- Books and previous data

- local sources : residents, historians, authorities

- maps/ topographical maps

- air photography

Cheap way of producing a lot of data concerning thesite.

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Site Visit and Visual Assessment

Visit site to identify obvious problems and causesfor our concern.

Identify problems that we got from desk study.

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Detail Examination/ Special Studies

Geophysical surveys.

- There are 5 types of geophysical surveys:

1) Ground Penetrating Radar (GPR)2) Resistivity survey.

3) Seismic survey.

4) Magnetic survey.5) Gravity survey.

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Ground Penetrating Radar (GPR)

- Microwave are transmitted form the device mounted

on the trolley, and is reflected off the rock structures.

- Suitable for shallow ground investigation.

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Resistivity survey

- Injecting current into the earth's subsurface, current

is then detected by the electrode.

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Magnetic survey.

-Using a magnetometer, an operator can measureminor changes in the magnetic field.

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Seismic survey.

- Use shockwave produce by hammer or explosionswhich become reflected or refracted from geological

boundaries.

(a) Reflection seismology

Used for deep surveyssuch as those used to identify oil and gas deposits.

(b) Refraction seismologyUsed for shallow surveys

such as site investigation. As the shockwave pass

down from the upper layer to the layer beneath, they

speed up and eventually return to the surface to be

recorded at geophones.

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Gravity survey.

- Minute change in the gravitational field are recorded.A negative anomaly may indicate the presence of a

cavity under the surface.

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Ground Investigation

Objective :

1) To assess suitability of the site & environment for

the purposed work.

2) To enable adequate info for design to be prepare.

3) To plan the best construction method.

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Ground Investigation

There are 7 types of ground investigation.

Uses of different types of ground investigation

depends on :

- Site

new site need more detail studies.

- Locationon land or on water.

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1) Excavation

- Shallow trial pit, deep trial pit.

2) Boring.

- Hand auger, light cable percussion boring, wash

boring, rotary hole drilling.

3) Sampling.

4) Probing.

5) Test Borehole.6) Remote Sensing.

7) Mapping.

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THANK YOU