844

THE COLLIERY GUARDIAN.

April 26, 1918.

built into the brickwork (fig. 2). The rams are con-
nected by a circular system of tubes, and the hydraulic
pressure is obtained from a steam force pump delivering
to an accumulator, which gives a steady even pressure
and avoids shock.

Where the ground is of a very loose, sandy character
the brick shaft may have to be carried above the surface,
as in fig. 3, the brickwork being laid on a reinforced con-
crete curb. Into the concrete is built a cast iron “ anchor
ring ” to which the pressure ring taking the back pres-
sure of the rams is connected by anchor rods. The rams
are bolted to the pressure ring to prevent falling when
the pressure is released. In sinking shafts through

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Fig. 7.—View of Steel Piles as Arranged at Start.









quicksands, the lowering of the tubbing can be assisted,
if necessary, by a continuous flow of water made to pass
down the shaft lining to the cutting shoe, provision
being made for this in the tubbing castings. The slurry
from boring Operations is washed up to the surface
through the hollow rods. The water flush around
the periphery of the cutting shoe greatly facilitates the
sinking of the cylinders and the keeping of them on the
downward move. The rubbish from the sjiaft may be
removed by an elevator or by a “ grabber,” by the old
sack method, or on the improved sack-borer principle,
according to the class of material to be dealt with.

The sack-borer is used when sinking through loose
water-bearing ground at the surface. The shaft is bored
out and the rubbish caught in sacks, which, in the
improved form are raised by the winding engine without
lifting the borer and boring rods, thus effecting much
saving in time. The old sack-borer system was slow
but certain, and was used when other means failed.
Originally the small contents of the sack were brought
to the surface with the borer and rods, and much loss of
time was involved.

Piling through Sand.

One of the most troublesome operations in shaft
sinking is carrying a shaft through running sand,
gravel, or clay, owing to the shifting and unreliable
nature of the. ground and also on account of the invari-
able presence of much water. In this case the shaft
must be set out to a sufficiently large diameter' at
the top of the loose strata, the thickness of which has
been determined by a preliminary bore, so as to permit
of the diameter finishing at the desired dimension when
firmer strata is again reached.

Wood piles, hooped and shod with iron, are driven
down, tier within tier (fig. 4), until the stone-head or
reliable strata is reached. The large diameter at the
top is previously determined from the known depth of
the sand and the number of tiers of piles required to
cany through this material, sufficient increase being
made in the diameter to allow for the space occupied
by the piles and cribs without encroaching upon the
finished diameter of the shaft.

A saving in the large diameter of the shaft at the
commencement is obtained by the use of interlocking
channel-bar steel piling (fig. 5) as made by the Inter-
locking Channel-Bar Company of Chicago, or the uni-
versal joist steel sheet piling of the British Steel Piling
Company. Mr. Charles Walker, mining contractor, has
also introduced a method of forcing down steel piles
carrying tubbing for sinking through alluvial deposits
and quicksands, aided by a pioneer- guide-ring. The
Walker piles are “ male” and “ female,” and groove and
tongue with each other.

W ood piling was used at Pram wellgate Moor- Colliery,
near Durham, for passing through bad ground, The
shaft started at 30 ft. diameter, and was sunk 120 ft. to
the stone head, where the diameter was reduced to
14 ft. 4 in. At Bowburn, near Durham, 156f ft. of sand,
gravel and clay were passed through to the stone head,
the shaft starting at 25 ft. and finishing at 15 ft.
diameter. At Horden Colliery (Durham), east pit, after
passing through the limestone, five tiers of 12 ft. piles
were necessary to carry the shaft safely through the
sand and into the coal measures, at a depth of 516 ft. In
sinking, the sand caved in, and the tiers of piles were
surrounded on the outside by thousands of bags of
concrete, which passed down behind the piling by their
own weight as the sinking proceeded to the bottom of
the sand.

Universal joist steel sheet piling (the British Steel
Piling Company) for mine shafts, wells, etc., is illus-
trated in fig. 6. A recent instance of its use is the
sinking of two shafts at the Hatfield Main Colliery,
near- Doncaster. Preliminary borings showed that

several beds of fine quicksand, from 4 to 5 ft. thick, as
well as soft clay beds, had to be passed through, and
large quantities of water were present. The piles used
consisted of 15 in. x 5 in. joists, with interlocking
clutches 6^ in. < 4 in., weighing 43 1b. per super, ft.
assembled. The piles were bent in the webs to a radius
for forming a circle 26 ft. 3 in. diameter, and were
33 ft. and 28 ft. long respectively in the two shafts.
They were erected in a circle (fig. 7). and a driving
plant was provided to travel around the outside of the
piles on curved rails. A direct-acting steam piling
hammer was used, weighing 36 cwt., but a 40 cwt.
hammer was necessary for the last few feet into the





s mdstone, where 1,250 blows were required to drive
the piles one foot. The piles were practically
watertight, the leakage being only about 5 gals, per
minute, and this could have been readily stopped by

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Fig. 8.—Interior View of Shaft showing Steel Piling.













caulking. Fig. 8 shows an interior view of the shaft
alter sinking.

The Haase System.

This system is used for sinking through quicksand
and gravel, and consists of driving down wrought iron
tubes placed side by side so as to form a lining to the
shaft. The tubes are 13 ft. long, 4 ft. diameter, and 2 in.
thick. Wood guides, with cast iron bars at top and
bottom, are attached to the shaft timbering to ensure
the tubes being driven perpendicularly.

The Honigmann Boring System.

The Honigmann system is used for sinking through
loose ground, such as surface sands, gravels, or clays.
It cons’sts in boring out the shaft and maintaining a
higher water level inside the latter than the natural
water level of the surrounding ground. In order to

support the loose sides of the shaft, the specific gravity
of the water in the shaft is raised from 1 to 1'2 by the
addition of clay. Compressed air is also forced down
a tube, placed within the hollow boring rods for the
purpose of raising the debris and sludge to the surface,
the principle of the action being similar to an air-lift
pump.

The Pneumatic or Caiason Process.

The pneumatic, compressed air, or caisson process is
adapted for- sinkings in quicksand and surface water-
bearing strata generally. It was successfully employed
by M. Triger in France about 60 years ago, and consists
in forming a caisson or cast iron cylinder of rings, built
up at the surface, and sinking the column of tubbing
so formed by excavating, from within, at the bottom
of the shaft. Water from the surrounding strata
is excluded by compressed air admitted to a
special air-tight compartment at the bottom of the
cylinder. The pressure of this air must be sufficient to
balance the head of water contained in the surrounding
strata. The system is limited to depths of 100 ft. to
120 ft., or pressure of 45 lb. per square inch—equivalent
to three atmospheres above the normal atmospheric
pressure. This is as much as average strong healthy
men can endure for practical purposes. Entrance
to and exit from the “ bell,” or compressed air chamber,
is gained through “air-lock” compartments in the usual
manner. Any water accumulating in the bottom of the
shaft is forced to the surface by compressed air through
pipes provided for the purpose.

To assist in the descent of the cylinder, the air-
pressure is released from the “ bell,” as this tends to
balance the weight of the cylinders. The descent may
also have to be forced by the application of dead
weight—such as quantities of pig iron, lead or bricks—
or by the employment of hydraulic rams. The buttress,
or upward force of the rams, is met by the dead weight,
applied at the surface, and the carriage, or framework.
This latter may also be anchored down to the ground.
When the cylinders have been sunk to the “ stonehead ” a
wedging curb is put in, and the tubbing plates are built
up from it so as to join up with the bottom of the
tubbing cylinder. On completion, the “ bell ” and the
inner or air tube are removed.

The system of sinking by the aid of compressed air is
similar to that employed for wells, river piers and other-
foundations in water-bearing ground, and consists essen-
tially of a bottomless caisson, not less than 6 ft. high,
which forms the working chamber containing compressed
air in which the material is excavated, thereby causing
the caisson to sink gradually. Access is obtained to the
working chamber through a vertical metal shaft placed
over an opening in the roof or
diaphragm, such shaft being
provided with an air-lock at the
top or bottom for the passage
of men and materials from the
open air into the compressed
air and out again.

The compressed air should
be kept as pure and fresh as
possible, and be drawn from an
outside source free from all
dust or pollution of any kind,
and should be frequently re-
newed. The chamber- should
be lighted by electric light to
avoid pollution of the air and
to minimise heating.

Upon emerging direct from
a high air pressure into the
open air a man may feel insen-
sible ; and in some cases dan-
gerous and even fatal results
have occurred. These effects
are avoided by resting for some
time in the “ air-lock ” both
before entering and after-
leaving the compressed ait-
working chamber. The passage
from the high air pressure to
normal atmospheric pressure,
and vice versa, should be as
gradual as possible.

Hydraulic Shock or “ Water-
Hammer ” Boring.

One of the latest develop-
ments in shaft sinking is the
system of boring by hydr aulic
shock or water hammer, which
force is transmitted to a number
of cutters or chisels at the
bottom of the shaft. This
method, which was introduced
by Wolski, is intended for
sinking in firm ground con-
taining water which cannot be
dealt with by pumping. Water
under a pressure of about 450 lb.
to the square inch is forced
through hollow rods and gives
a “ water-hammer ” action on
pistons connected, ^through
strong retractive springs, to
bits or- chisels which are driven

forward against the bottom of the shaft. The spent or
waste water escapes through orifices in the bit shoe
on to the shaft bottom, and flushes the debris up to a
mud tank mounted on top of the boring tool. This tank
is cleared out when the tool is raised to the surface.
The writer is not aware of this tool having yet been used
in this country for practical boring purposes.

The Pattberg Percussive Borer.

The Pattberg system consists in operating a large
percussive boring tool in a somewhat similar manner to
the Kind-Ohaudron process, but the additional feature
consists in forcing pressure water through hollow boring
rods to the cutters at the lower end of the tool, thus
flushing out the bottom of the shaft at each blow. The
slurry is raised by means of a current of compressed
air. The system has proved useful in boring through