Apparatus for Driving Tunnels and Sinking Shafts.
Year: 1886

page_text: Date of Application, 14th Apr., 1886.
Complete Left, 11th Jan., 1887.
Complete Accepted, 11th Feb., 1887.
Apparatus for Driving Tunnels and Sinking Shafts.
I, JAMES HENRY GREATHEAD of No. 8 Victoria Chambers, Westminster in the
County of Middlesex, Engineer do hereby declare the nature of this invention to he
as follows:-
In my Specifications No. 1738 of 1874 and No. 5665 of 1884 I described means of
tunnelling by the action of currents of water directed on the material in front of a
tunnelling shield, and means of removing the displaced material. My present inven-
tion relates to improvements in the arrangement of such tunnelling apparatus and in
their application for sinking shafts, also to means of filling up and making good such
cavities or annular spaces as may be left outside the lining of a shaft or tunnel. In
driving a tunnel, instead of arranging the pumping machinery and the depositing
tanks in the completed portion of the tunnel as described in my former Specifications.
I provide for their accommodation in the shaft or outside of it where there is more
room, and I extend the pipes that communicate with the shield up to the level of the
natural water under which the tunnel is driven, or in cases where there is no such
water to a tank or reservoir furnishing the supply of water for effecting the excavation
I take care to arrange the mouths of these pipes so that they open at or about the same
level in the water, thus balancing or nearly balancing the pressure of the flow and
return, and also when there is water above the tunnel balancing its pressure in the
space in front of the shield. In like manner, in sinking a shaft, the flow and return
pipes are carried up the shaft and open into water above so as to approximately
balance the pressures. In cases where there is considerable length of pipe in order to
reduce the pressure of the shield due to the frictional resistance of the return pipe I
prefer to create an additional current in that pipe by a pump, injector or otherwise.
In sinking a pump or driving a tunnel the shield employed is usually made with a lip
overlapping the extremity of the completed lining, and consequently as the shield is
advanced there is an annular external space left around the lining. There are often
also other cavities depending on the nature of the material excavated. In order to
fill these spaces and make good around the lining it has been usual to force through
holes of the lining liquid cement which sets forming a solid filling. In order to eject

page_text: this cement, I employ apparatus of the following description. I provide a vessel in
which the cement is mixed with water, and closing it tightly while a pipe leading from
it is connected to a hole through the lining, I subject its contents to air or water
pressure sufficient to force them through the pipe into the external space. When the
contents of the vessel have been delivered I connect the pipe to a water service, and,
reducing the pressure in the vessel, I thus cause water to flow back through the pipe
clearing it and at the same time providing a fresh supply of water for mixing. When
water pressure is used to effect discharge of the cement, I separate the water from
the cement by a diaphragmn or loose fitting piston in the mixing vessel.
ABEL & IMRAY,
28, Southampton Buildings, London, W.C.,
Agents for the Applicant,
JAMES HENRY GREATHEAD of No. 8 Victoria Chambers, Westminster in the
County of Middlesex, Engineer do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascertained in
and by the following statement :-
In my Specifications No. 1738 of 1874 and No. 5665 of 1884 I described means of
tunnelling by the action of currents of water directed on the material in front of a
tunnelling shield, and means of removing the displaced material. My present inven-
tion relates to improvements in the arrangement of such tunnelling apparatus and in
their application for sinking shafts, also to means of filling up and making good such
cavities or annular spaces as may be left outside the lining of a shaft or tunnel. In
driving a tunnel, instead of arranging the pumping machinery and the depositing
tanks in the completed portion of the tunnel as described in my former specifications,
I provide for their accommodation in the shaft or outside of it where there is more
room, and I extend the pipes that communicate with the shield up to the level of the
natural water under which the tunnel is driven, or in cases where there is no such
water to a tank or reservoir furnishing the supply of water for effecting the excavation.
I take care to arrange the mouths of these pipes so that they open at or about the
same level in the water, thus balancing or nearly balancing the pressure of the flow
and return, and also, when there is water above the tunnel, balancing its pressure in the
space in front of the shield. In like manner, in sinking a shaft, the flow and return

page_text: pipes are carried up the shaft and open into water above so as to approximately
balance the pressure.
In cases where there is considerable length of pipe, in order to
reduce the pressure at the shield due to the frictional resistance of the return pipe, I prefer
to create an additional current in that pipe by a pump, injector or otherwise. In
sinking a shaft or driving a tunnel, the shield employed is usually made with a lip
overlapping the extremity of the completed lining, and consequently, as the shield is
advanced, there is an annular external space left around the lining. There are often
also other cavities depending on the nature of the material excavated. In order to
fill these spaces and make good around the lining, it has been usual to force through
holes of the lining liquid cement which sets, forming a solid filling. In order to
eject this cement, I employ apparatus of the following description.
provide a vessel
in which the cement is mixed with water, and closing it tightly, while a pipe leading
from it is connected to a hole through the lining, I subject its contents to air or water
pressure sufficient to force them through the pipe into the external space. When the
contents of the vessel have been delivered 1. connect the pipe to a water service, and,
reducing the pressure in the vessel, I thus cause water to flow back through the pipe
clearing it and at the same time providing a fresh supply of water for mixing. When
water pressure is used to effect discharge of the cement, I separate the water from the
cement by a diaphragm or loose fitting piston in the mixing vessel.
Fig. 1 of the accompanying drawings is a longitudinal section of part of a tubular
tunnel lined with metal, shewing arrangements according to my invention for dis-
posing of the debris of excavation externally.
Fig. 2 is a section of the apparatus for injecting material to fill the vacuity around
the metal lining.
As described in my previous Specifications, the shield A has a tubular part B or lip
attached to it, this part overlapping the front portions of the metal lining C. The
two pipes D and E, the one conveying the current of water to the nozzles of the shield,
and the other conveying water mixed with debris back from the excavation in front of
the shield, are both carried up the shaft R and put in communication with the external
water, so that the pressure in front of the shield due to the height of the external water
above it is balanced, and all that has to be done by the pump G, (which may be
situated in any convenient part of the pipe D) is to create the necessary current in the
pipe, not to overcome any unbalanced pressure. When the pipes D and E are of con-
siderable length, it is of advantage to apply in some convenient part of the pipe E an
additional pump or it might be an ejector to overcome the friction of the flow along
the pipe, which would otherwise operate as a back pressure on the fluid in front
of the shield. The pipe D has a suction nozzle S immersed in the water, and
the pipe E has a discharge branch T which is also immersed in the water or in a
barge or floating vessel in which the debris is deposited. When there are tidal or
other variations of the water level, the branch T should be jointed to E so that it
can accommodate itself to the change of level, its mouth remaining still immersed in
the water, so as to maintain the balance of pressure in the circuit. In order to allow
for the advance of the shield from time to time the parts,D' and E' of the pipes D and E
are made telescopic, so that, as the shield is being pressed forwards by the hydraulic
or other jacks J, the pipes D and E are telescopically extended, and their valves being
shut, the telescopic parts can be closed in and additional lengths of pipe can he intro-
duced between the separated flanges. When the shield is advanced, its backwardly
extending lip B leaves behind it an annular vacuity V around the lining C. In order
to fill this vacuity, I provide through several of the segments of the lining C holes fitted
with plugs, which can be removed when required to permit of introducing the end of a
pipe from a vessel U as shewn in Fig. 2. This vessel is charged with liquid cement
and is closed air tight; compressed air is then forced into it and this causes the cement
to flow from the vessel into the vacuity V where it sets, making a solid filling and
covering the lining C with a protecting coat. The vessel U may have within it an
agitator consisting of arms projecting from a spindle that can be turned from outside
the vessel. This is a convenient arrangement for mixing cement with water within the

page_text: vessel itself. Instead of using compressed air for discharging the cement from the
vessel U, water under pressure may be employed; in this case it is of advantage to
use a floating piston to keep the water above separate from the cement below it.
Although I have shewn in Fig. 1 arrangements suitable for excavating a horizontal
tunnel or subway, obviously they could be applied with suitable modifications to the
excavation of a tunnel or subway more or less inclined or to the sinking of a shaft
vertical or nearly so.
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 apparatus for driving tunnels and sinking shafts, in combination with a
shield pushed forward as the excavation advances and provided with nozzles by which
water currents are directed on the material to be excavated, a pump with flow and
return pipes extending backwards and upwards to communicate with the external
water, substantially as and for the purposes herein set forth.
2. For filling with cement the annular vacuity left around the lining of a tunnel
or shaft by the advance of the lip of the shield, apparatus constructed and applied
substantially as described with reference to Fig. 2.
ABEL & IMRAY,
Agents for the Applicant.