TUNNELLING APPARATUS
Year: 1884

page_text: I, JAMES HENRY GREATHEAD of N° 8 Victoria Chambers, Westminster, in the
County of Middlesex, Civil Engineer, do hereby declare the nature of my invention
for "TUNNELLING APPARATUS" to be as follows:-
In the Specification to Letters Patent granted to me on the 16th May 1874
N° 1738, I described means of tunnelling by the action of currents of water directed
on the material in front of a tunnelling shield, so as to scour out debris from the
front space and send it back into receptacles situated in the excavated part of the
tunnel, tools or boring apparatus being employed where necessary to disintegrate
the material in front of the shield.
My present invention relates to apparatus for this purpose, so arranged as to
secure great economy of the power employed, and to provide against casual inter-
ference with the action of the apparatus.
The currents of water which issue from the front of the shield have to act
against the pressure of the external column of water. This column acts also in
favor of the inflow of the mixed water and debris. I therefore make the pipes and
vessels as well as the pump employed to create the current, constitute a closed
circuit, so that whatever pressure may resist the outflow, this is counterbalanced
by equivalent pressure aiding the inflow. I also put this closed circuit in commu-
nication with a column of water arranged in the shaft or elsewhere, of head
equivalent to that of the external water, so that, in advancing the shield, there is
free escape for the water displaced by its advance. The closed receptacles in which
the debris is deposited, have to be cleared out from time to time. For this purpose,
I bring under the receptacle a skip or moveable vessel which is filled with water at
such a level that the lip of a passage from the receptacle above is immersed in the
water. Then, on opening a valve in this passage, the sand and debris descend from
the receptacle into the skip, while the water ascends from the skip into the
receptacle. For the purpose of scouring out the pipes by flushing, I provide a
communication between the outflow and the inflow pipe, as near as possible to the
front of the shield, and while the pump is in action, I shift valves, so as to cause
the current to follow the course of the pipes without passing through the front of
the shield; and in order to ensure that this flushing shall take place, I interlock
with the valves mentioned above, the supply valve of the pump, so that the latter
cannot be closed for the purpose of stopping the pump unless the former are first

page_text: opened to establish the flushing circulation. To provide against interference by
detached boulders, I make the front of the shield with a recess or pocket projecting
inwards at its lower side, and I provide suitable tools passing through stuffing
boxes into this pocket, so that a workman within the shield can, by the use of
these tools, break up boulders that may collect in the pocket, into fragments small
enough to be carried in by the inflow current. When a boring head is used,
I make it with two arms, and, immediately behind it, I fix, in front of the shield, a
partition extending down to nearly the centre line, which partition forms the front
of an air chamber in front of the face of the shield. When it is necessary to adjust
or replace the boring tools, I turn the boring head until its arms are horizontal and
then draw it back and turn the head so that one of the arms stands up within the
air chamber bebind the partition. By admitting to this chamber air at sufficient
pressure to overbalance that of the external water, I can get access to this chamber
from the air lock of the shield.
ABEL & IMRAY,
Agents for the Applicant,
28, Southampton Buildings,
London, W.C.
I, JAMES HENRY GREATHEAD, of N° 8 Victoria Chambers, Westminster in the
County of Middlesex, Civil Engineer, do hereby declare the nature of my invention
for "TUNNELLING APPARATUS "and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement:-
In the Specification to Letters Patent granted to me on the 16th May 1874,
No 1738, I described means of tunnelling by the action of currents of water directed
on the material in front of a tunnelling shield, so as to scour out debris from
the front space and send it back into receptacles situated in the excavated
part of the tunnel, tools or boring apparatus being employed where necessary to
disintegrate the material in front of the shield.
My present invention relates to apparatus for this purpose, so arranged as to
secure great economy of the power employed, and to provide against casual inter-
ference with the action of the apparatus.
The currents of water which issue from the front of the shield have to act against
the pressure of the external column of water. This column acts also in favor of
the inflow of the mixed water and debris. I therefore make the pipes and vessels
as well as the pump employed, to create the current, constitute a closed circuit, so
that whatever pressure may resist the outflow, this is counterbalanced by equivalent
pressure aiding the inflow. I also put this closed circuit in communication with a
column of water arranged in the shaft or elsewhere, of head equivalent to that of
the external water, so that, in advancing the shield, there is free escape for the
water displaced by its advance. The closed receptacles in which the debris is
deposited, have to be cleared out from time to time. For this purpose I bring

page_text: under the receptacle, a skip or moveable vessel which is filled with water at such a
level that the lip of a passage from the receptacle above is immersed in the water.
Then on opening a valve in this passage, the sand and debris descend from the
receptacle into the skip, while the water ascends from the skip into the receptacle.
For the purpose of scouring out the pipes by flushing, I provide a communication
between the outflow and the inflow pipe, as near as possible to the front of the
shield, and while the pump is in action, I shift valves, so as to cause the current to
follow the course of the pipes without passing through the front of the shield; and
in order to ensure that this flushing shall take place, I interlock with the valves
mentioned above, the supply valve of the pump, so that the latter cannot be closed
for the purpose of stopping the pump unless the former are first opened to establish
the flushing circulation. To provide against interference by detached boulders,
I make the front of the shield with a recess or pocket projecting inwards at its
lower side and I provide suitable tools passing through stuffing boxes into this
pocket, so that a workman within the shield can, by the use of these tools, break
up boulders that may collect in the pocket, into fragments small enough to be
carried in by the inflow current.
When a boring head is used I make it with two arms, and immediately behind
it, I fix in front of the shield a partition extending down to nearly the centre line,
which partition forms the front of an air chamber in front of the face of the shield.
When it is necessary to adjust or replace the boring tools, I turn the boring head
until its arms are horizontal and then draw it back and turn the head so that one
of the arms stands up within the air chamber behind the partition. By admitting
to this chamber air at sufficient pressure to overbalance that of the external water,
I can get access to this chamber from the air lock of the shield.
Fig. 1 of the accompanying drawings is a longitudinal section of part of a
tubular tunnel with its shield shewing arrangements according to my invention for
balancing the pressure of external water. A is the front of the shield from which
extends backwards a cylindrical part B fitted to slide over and along the completed
part C of the tunnel. Through the front A tools a pass through stuffing boxes to
assist in loosening the material in front, and water is forced through the shield by
the pipe D and nozzles d to scour out the debris which returns with water by the
pipe E, as described in the Specon above referred to. According to my present
invention I form a closed circuit of the pipes D and E and the tank F which
receives the debris, employing at any convenient part of the pipe D a helical or
other pump G to create a current of the water. Thus, whatever be the pressure of
the external water, the only power required for effecting circulation in the circuit
is that necessary for creating the scouring current. A back flow pipe H is provided
communicating at its hinder end with the external water or with a discharge under
equivalent pressure, so that the water displaced by the advance of the shield may
find its way out without being forced through or disturbing the material through
which the shield is advanced.
A pipe P is provided to make, when required, communication between D and E
for scouring out the latter. For removing debris deposited in the tank F, I provide
outlets f furnished with valves under which outlets I bring trucks K charged with
water. Each of the outlets f has a lip projecting down into the water of the truck
so that on the valve being opened the debris from the tank descends into the truck
while water from the truck ascends to take its place in the tank. When this
operation is performed, valves e in the pipes D, E and H are closed to relieve the
tank from the pressure. In case boulders are displaced in front of the shield, a
pocket L is provided in which the boulders can be broken up by tools l, or from
which they might be removed by providing behind or above L an air-lock, as
described with reference to Fig. 3 of the drawings annexed to my previous Specon
above referred to.
Fig. 2 is a part longitudinal section and Fig. 3 an end view of the arrangement
which I adopt for giving access to repair or replace the tools when a boring head
is used. In front of the shield I provide a diaphragm or partition M extending

page_text: down from the top to nearly the axis of the tunnel, the space between this partition
and the front A of the shield being, when required, charged with compressed air
by a pipe N, so that it can be entered by a workman from an air lock. The boring
head O being turned so that its two arms lie horizontally, as indicated in Fig. 3, is
drawn backwards, and then it can be turned partly round so as to bring one of the
arms into the air space between A and M, as indicated in Fig. 2 and by the dotted
lines O¹ in Fig. 3.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1. In tunnelling in such a manner that water and debris displaced from the front
of a shield return to receptacles within the tunnel, arranging the pipes and
receptacles so as to form a closed circuit, substantially as and for the purpose herein
set forth.
2. In combination with the circuit referred to in the preceding claim, a pipe for
discharging back through the tunnel the water displaced by the advance of the
shield.
3. Discharging debris from a receptacle by outlets dipping into water, so that as
the debris descends the water takes its place in the receptacle, substantially as
herein described.
4. The method of obtaining access to the tools of a boring head in front of a
shield, substantially as described with reference to Figs. 2 and 3.
Daten uns 7 day of December 1001.
ABEL & IMRAY,
Agents for the Applicant,
28, Southampton Buildings,
London, W.C.