This document discusses different types of boring methods used for soil exploration, including auger boring, shell and auger boring, wash boring, percussion boring, and rotary boring. It provides details on how each method works and the types of soils it can be used for. The document also discusses different types of samplers used including open-drive, thin-walled, split-spoon, piston, and scraper bucket samplers. It provides a brief overview of how each sampler works and the type of samples it can obtain.

1. Boring – Types of Boring
The types of boring methods commonly adopted for soil
exploration are as under :-
(a) Auger boring
(b) Shell and Auger boring
(c) Wash boring
(d) Percussion boring
(e) Rotary boring

2. The examination of the sub-soil conditions for
simple buildings to be erected in clayey or
sandy soil can be best performed by a post hole
auger. The auger is held vertically and is driven
into the ground by rotating its handle by
applying leverage. The auger is pressed down
during the process of rotation. At every 30 cm
of depth penetrated, the auger is taken out and
the samples of the soils are collected separately
for examination. This method can be
conveniently used for soil penetration up to 15
m depth. The type of augers commonly used
are shown below. For deeper holes or in
grounds where gravel, boulders or comp act
material is present, this method is not adopted.
During the continuous process of pressing and
simultaneous rotation, the auger is gently
driven into the ground. After sometime when
auger reaches a finite depth and is completely
filled with soil, it is taken out on the ground
surface and the soil is removed from the auger
(a) Auger boring :

3. (b) Shell and Auger boring :
In this method different type of tools have to be
adopted for boring. In case of soft to stiff clay,
cylindrical auger consisting of a hollow tube of 75 to
200mm in diameter with a cutting edge at its bottom is
used. In case of various stiff and hard clay, shells with
cutting edge or teeth at lower end are to be adopted
while in case of sandy soil, shells or sand, pumps are
used for boring. By this method it is possible to make
vertical boring up to 200 mm in diameter and 25 m in
depth by use of a hand rig. By use of mechanical rig it
is possible to extend the depth of the bore hole up to
50 m. The samples of the soil are recovered at regular
intervals (or whenever there is a change in strata) for
conducting tests in laboratory for identification of soils
and establishing properties of the sub-soil strata at
various depths. A type of percussive drilling used for
site investigation which is particularly useful in
obtaining samples of sand and gravel from below the
water table but, by using a chisel in conjunction with
the shell, the hardest rocks may be penetrated.

4. (c) Wash boring :
For test boring over 3 meter in depth, this method can be
conveniently used. In this method a hollow steel pipe known
as casing pipe or drive pipe is driven into the ground for a
certain depth. Then a pipe usually known as water jet pipe or
wash pipe, which is shorter in diameter, is lowered into the
casing pipe. At its upper end, the wash pipe is connected to
water supply system while the lower end of the pipe is
contracted so as to produce jet action. Water under
considerable pressure is forced down the wash pipe. The
hydraulic pressure displaces the material immediately below
the pipe and the slurry thus formed is forced up through the
annular space between the two pipes. The slurry is collected
and samples of material encountered are obtained by
settlement. In this process the particles of finer material like
clay, loam etc. do not settle easily and the larger and heavy
particles of the soil may not be brought up at all. Moreover, the
exact position of a material in the formation cannot be easily
be located. However the change of stratification can be
guessed from the rate of progress of driving the casing pipe as
well as the color of slurry flowing out. Yet the results obtained
by wash boring process give fairly good information about the
nature of the sub-soil strata. This method can be adopted in
soft to stiff cohesive soils and fine sand.

5. (d) Percussion boring :
Percussion drilling is a drilling method in which a heavy
hammering or cutting bit is attached to a cable and
inserted into the borehole. The heavy bit or hammer is
repeatedly lifted and dropped, thus boring through the
earth .The hammer is made of hardened steel with
carbide on the chisel-shaped bit. Cable percussion
boring is a common drilling method used for
geotechnical site investigations. This drilling method
allows the installation of casing inside the borehole
allowing for deep boreholes. It is the most convenient
and common method of intrusive geotechnical
investigation
Percussion drilling can be used to dig boreholes up to
60 m depth depending on ground conditions and
access to the site.
Different sample types can be retrieved using this
method such as:
1. Cohesive disturbed samples.
2. Granular disturbed samples.
3. Undisturbed samples.
4. Piston samples.
5. Split barrel samples (used standard penetration
testing).

6. (e) Rotary drilling:
Rotary drilling is used to form a deep observation borehole or for
obtaining representative samples of rock. The drilling method
involves a powered rotary cutting head on the end of a shaft, driven
into the ground as it rotates. The system requires lubrication (air,
water or drilling mud) to keep the cutting head cool.
There are two types of rotary boring, open-hole and core drilling.
Material recovered from open-hole drilling is mixed with the drilling
lubricant. It is unsuitable for effective sampling, and it is often
difficult to observe and record the strata. Open-hole boring is only
suitable for rapid drilling to enable core recovery at a greater depth
or for the installation of monitoring wells. Core drilling is carried out
using wire-line, double or triple-tube core barrels with diamond or
tungsten-tipped core bits.
Wire-line core barrels are rotated from the surface by rods normally
of the same diameter as the outer core barrel. The core is brought to
the surface within the inner barrel using a wire rope or attached line
to a recovery tool. This system is particularly suitable for superficial
or weak deposits, as any vibration from the drilling action is
minimized due to close-fitting rods used within the hole .The
conventional double-tube core consists of two barrels; the outer
barrel is rotated by the drill rods and carries the coring bit. The inner
barrel does not rotate, and the core passes up into this inner barrel,
enabling the sample to be recovered and brought to the surface .
With triple-core barrels, the non-rotating inner barrel contains a
removable tube or liner. At the end of each core run, this liner with
the core it contains is extracted and stored in a core box. This
method does not increase core recovery but is more likely to
preserve the core in original condition.

7. SAMPLERS – TYPES OF SAMPLERS
(a) Open-drive sampler
(b) Thin - wald sampler
(c) Split-spoon sampler
(d) Piston sampler
(e) Scraper bucket

8. (a) Open-drive sampler :
It consists of a steel tube with a screw
thread at each end. The lower end is
usually fitted with a cutting shoe but
sometimes with an extension piece.
The top end is fitted with a sample
head, which includes a non-reversible
valve. Non-return The valve allows air
and water to escape when the
specimen enters and closes the
specimen to the surface, thus retaining
the specimen inside the tube This is
the simplest and most common type of
model. A drive-type soil-sampling
device that is essentially a headpiece,
threaded to fit a drill rod, to which is
attached a removable length of thin-
wall brass or steel tubing.

9. (b) Thin-wald sampler :
Thin-walled models can be used to obtain
undisturbed specimens in soft clay and plastic
silt (IS : 11594,1985).However, No separate
cutting shoe is attached to the lower end, but the
bottom of the specimen itself is machined to act
as a cutting edge High-quality undisturbed
samples are possible if the soil is not disturbed
during Ar <10% and boring operation. This model
can be used more conveniently in experimental
pits and shallow boreholes. Thin-walled samplers
consist of a steel tube whose lower end is shaped
to form a cutting edge . These samplers are
usually only suitable for fine soils up to firm or
stiff consistency, and free from coarse particles,
although samples have been successfully obtained
from very stiff soils. They can give Class 1
samples of all fine soils, including sensitive clays,
provided that sinking the borehole has not
disturbed the soil. Samples between 70 mm and
120 mm in diameter are usually obtained.

10. (c) Split-spoon sampler :
The split spoon sampler is a tube split into two
equal halves lengthwise. The two halves are
locked together during the sampling activities
and released to retrieve the samples. At bottom
end of the sampler sits a driving shoe. This is
what cuts into the soil and provides the sample
that goes up into the tube. At the other end of
the tube is a coupling that allows it to connect to
the drilling rod. Once a sample is taken, the
operator removes the ends from the tube. This
allows the tube to “split” open. Representative
samples can be taken and put into containers for
shipping to a lab for analysis, observed and field
tested in the field, or discarded in a proper waste
container if not warranted for the investigation.

11. (d) Piston sampler :
The hydraulic piston sampler is designed for taking
undisturbed samples in very soft to stiff clays. The
necessary hydraulic load for operating the equipment is
generated from the hydraulic power unit on a drilling
rig, or by using a purpose-designed hydraulic power
pack available from Archway.
In sampling clays or silts, Piston sampler is lowered into
boreholes and the piston is locked at the bottom of the
sampler. This prevents debris from entering the tube
prior to sampling. After reaching the sampling depth,
the piston is unlocked so that the piston stays on top of
the sample going into the tube.
In sampling clays or silts, Piston sampler is lowered into
boreholes and the piston is locked at the bottom of the
sampler. This prevents debris from entering the tube
prior to sampling. After reaching the sampling depth,
the piston is unlocked so that the piston stays on top of
the sample going into the tube. Prior to the withdrawal
of the sampler, the piston is locked to prevent the
downward movement and the vacuum generated
during the movement of the piston from the sampler’s
end aids in retaining the samples recovered. As such,
sample recovery is increased by using Piston samplers.

12. (e) Scraper bucket :
The scraper bucket sampler contains a
vertical slit at its upper portion and a
driving point at its bottom. As the sampler
is rotated, the scrapings of the soil enter
into the sampler cylinder through the
vertical slit. When soil deposite are sand
mixed with pebbles, obtaining samples by
split spoon with a spring core catcher may
not be possible because the pebbles may
prevent the springs from closing. In such
cases , a scraper bucket may be used to
obtained disturb representatives samples
The scraper bucket has a driving point and
can be attached to a drilling rod .
The sampler is driven down into the soil
and rotated , and the scraping from the
sides falls into the bucket