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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