FOUNDATION ENGINEERINGBFC 4043

BORING METHODS

MOHAMAD FITRI B MOHD AZLAN AF070135MOHD HAFIZ B AWANG AF070144ASMANIEZA BT IBRAHIM AF070142AINNURIDA BT MOHD TAJUDIN AF070143HAKIMAH BT KAMARUZAMAN AF070139NAJUWA BT ZAHARI AF070131

Boreholes

• used for soil classification and identification purposes or for the taking of samples

• to determine the nature of the ground usually below 6m depth

TYPES OF BORING METHOD COMMONLY USE IN MALAYSIA

a) ROTARY BORING

• Hole advanced by cutting bit attached to the bottom

of drill string and hydraulic thrust with cuttings

transported upwards by drilling fluid/water.

• Use compatible casings and rods, drag and cutting

bits varying with soil types.

• Almost all water discharged sideway

Advantages Disadvantages

Most rock formations can be drilled. Requires capital expenditure in equipment

Water and mud supports unstable formations

Water is required for pumping

Fast There can be problems with boulders.

Operation is possible above and below the water table

Rig requires careful operation and maintenance

Possible to drill to depths of over 40 meters.

Possible to use compressed air flush

b) LIGHT PERCUSION DRILLING

• This drilling method has been used in China for over 3000 years.

• also known as ‘shell and auger’ drilling.• It is consist of:1. A collapsible ‘A’ frame, with a pulley at its top.2. A diesel engine, connected via a hand-operated

friction clutch 3. A winch drum which provides pulling power to

the rig rope

• Percussion boring is used for land-based ground investigation, water supply, groundwater observation and monitoring and mineral exploration.

Percussion drilling in clays• use a steel tube known as a clay cutter• clay cutter normally has a solid or slotted weight,

called a sinker bar.Percussion drilling in sands or gravels• In granular materials, such as sands or gravels, a shell

is used• At least 2 m of water is put in the bottom of the

borehole, and the shell is then surged, moving about 300mm up and down every second or so

Advantages and Disadvantages

Advantages Disadvantages

Simple to operate and maintain Slow, compared with other methods

Suitable for a wide variety of rocks. Equipment can be heavy

Operation is possible above and below the water-table

Problems can occur with unstable rock formations.

It is possible to drill to considerable depths

Water is needed for dry holes to help remove cuttings

b) Auger boring• simplest and most economical method of drilling holes in soft soils •should be taken carefully of auger from the ground may generate suction in the borehole which can disturb the soil to be sampled

Advantages Disadvantages

-little or no surface disruption and the spoil is removed by augers which is a dry method.

-lengths & obstacles in the bore path.

OTHER TYPES OF BORING METHODa) Hand auger boring

• Extremely suitable for soil research. Example : Dutch auger, gravel auger, small helical auger barrel auger, spiral auger .

• Commonly use in SI is lawn auger and use diameters between 100-200mm.

• Each type of auger have their own essential.• boring depth depends on various factors :

groundwater, soil profile, and the characteristics of the material.

ADVANTAGES DISADVANTAGES

•Inexpensive. •Slow, compared with other methods.

•Simple to operate and maintain •Equipment can be heavy.

•Problems can occur with unstable rock formations.

•Water is needed for dry holes.

b) MECHANICAL AUGERContinuous Flight Auger (CFA)•A mobile base fitted with a hollow-stemmed flight auger which is rotated to required depth of pilling.•Effective on soft ground and enables to install a variety of bored piles of various diameters that able to penetrate a multitude of soil conditions.•Operation of rotary auger soil must free : tree roots, cobbles, and boulders, and must be self-supporting.

Advantages Disadvantages

Quicker to erect and dismantle The soil condition must be

stable to use this method

Able to use variety diameter • Need the high skills to handle

c) WASH BORING

• This method uses chopping bit to cut the soil and

water is pumped through a string of hollow

boring rod and released under pressure through

narrow hole to the lower end of rod.

• Wash boring can be used in most type of soil and

slower progress for coarse and large gravel size.

Advantages Disadvantages

The soil immediately below the hole remains undisturbed

Should not be used when undisturbed sample are desired above ground

water level

Light and inexpensive equipment and can be used for small and large hole

Not suited in very soft soil, fine to medium grained cohesion less soil

and in hard and cement soil

Not obstruct ground water observation

d) WATER JETTING

• This method made the hole advanced by jetting

of high pressure water downwards into soil below

casing and surging and rotating action of casing.

• The hole mainly by destructive forces of water

under high pressure and return water outside of

the casing.

Advantages Disadvantages

Require little skill to handle Volume of soil contaminated with water

Fast

Cheap

e) DIRECTIONAL BORING• Horizontal directional drilling(HDD).• Install underground pipes along a prescribe• bore path from the surface.• Eg : telecommunications, power cable

conduits, water lines, sewer lines, gas

lines, oil lines, product pipelines and

environmental remediation casings.

Advantages Disadvantages

Less traffic disruption Deeper installation possible

Lower cost Longer installation possible

No access pit required

Shorter completion times

Safer for the environment