Improvements in or relating to Means or Apparatus for Sinking Shafts, Driving Tunnels, or the like.
Year: 1896

page_text: Date of Application, 3rd Jan., 1896-Accepted, 25th Apr., 1896
COMT DIE DI BUITIGATION.
Improvements in or relating to Means or Apparatus for Sinking
Shafts, Driving Tunnels, or the like.
A communication by RICHARD PENNEFATHER ROTHWELL, of 253 Broadway,
in the City, County and State of New York, United States of America, Civil
Engineer.
I, WILLIAM PHILLIPS THOMPSON F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, 118 New Street, Birmingham in the
County of Warwick and 31 High Holborn in the County of Middlesex, Civil
Engineer, do bereby 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 :-
The invention relates to means for sinking shafts and driving tunnels, and it has
for its object to automatically guide a movable caisson or shield; to pack the
joint or joints between a shield and a shaft or tunnel lining; to stop or pack the
space between the shaft or tunnel wall and the lining; and to provide for
the continuous removal of excavated material without interference with the
introduction of the lining segments and the continuous building of said lining;
and it consists in the construction hereinafter described and particularly pointed out.
In the accompanying drawings:
Figure 1 is a central longitudinal section of a portion of a lined shaft and of
a movable caisson or shield, jacks for pushing the shield being shown in full
lines;
Figure 2 is a similar view of a tunnel both figures embracing a diagram of
valve controlling devices;
Figure 3 is an enlarged view partly in section of a valve and valve controlling
devices;
Figures 4 and 5 are side elevations of details;
Figure 6 is a partial elevation of a modification ;
Figures 7 and 8 are sectional views of modifications of packing.
Numeral 1 indicates the rock or native wall of a shaft and 2 a lining for the
same built of segments bolted together in manner too well known to need further
description. 3 denotes a shield or caisson having double walls 4 and 5; and
6 denote hydraulic jacks adapted to force the shield forward into and through
the material to be excavated. These jacks are situated between a seat 3' made
fast to the shield, and the front of the lining. The two walls 4 and 5 which are
separated sufficiently to permit workmen to enter between them to bolt together
the lining segments are joined by a curved wall 51 having a contour substantially
as illustrated to present as little obstruction to the movement of the shield as
practicable. Any suitable apparatus for forcing the shield forward may be
employed. 7 indicates pipes adapted to throw jets of water toward the axis of
the shaft or tunnel within the front part of the shield for the purpose of aiding
in the disintegration and removal of the material.
In sinking shafts through soft ground by the method described in my corre-
spondent's Patent dated May 13th, 1890, and numbered 7431, and also in the
operation of making tunnels it is very important that the shield or caisson such as

page_text: herein illustrated be pushed forward evenly all around. When the admission of
power to the jacks which push the shield is regulated directly by the workmen
this is difficult of attainment, some of the jacks being pushed out faster than
others.
This deflects the direction of the shield movement, causing undue strain in its
back end and in the shaft or tunnel lining and binding the shield, rendering it
very difficult to put in the lining segments and causing delays and dangers to the
work. To overcome these difficulties the admission of power is regulated to the
jacks automatically so that if one side of the shield advances a sinal distance
ahead of the other, the admission of power to the jacks on that side will bo
automatically throttled or altogether cut off until the other side has caught up
when the power will again be automatically admitted and the shield will go forward
at practically the same rate all around.
This automatic regulation can be applied equally well to the case of a tunnel
shield pushed forward horizontally or at any angle of inclination.
k
This very desirable object is accomplished by utilizing the force of gravity in
any convenient manner, as by the devices next to be described. Such devices are
indicated at A in Figure 1 and at B3 in Figure 2 and are shown on a larger scale
in Figure 3. In Figure 1, a denotes the main pipe for a fluid under pressure and
a its valve. denotes a transverse or annular pipe communicating with the
inlet pipe a and with several branches one of which is indicated at d its valve being
denoted by e. Each branch d communicates with a short transverse pipe which
latter communicates with a group of preferably from four, to six or more pipes 9
each having a valve b. The automatic regulation herein described is applicable
either to the valves in individual pipes 9 or to valves e in pipes d mediately
controlling admission of fluid to the groups of pipes supplied from transverse
pipes f. In practice the various pipes may also be supplied with valves adapted
to be manipulated by hand.
Referring to Figure 3b denotes a valve casing situated in a conduit 9 through
which a medium of power such as water or other fluid is conveyed under pressure
to the jacks. 10 is a bracket and 11 a lever pivotally supported thereon and also
pivotally connected as by a link 121 with a valve stem 12. To the upper end of
the lever 11 is connected by a link 13, an armature 14 which is extended axially
through a series of coils 15 of insulated conducting wire. Each coil is connected
by a conducting wire with a switch table 16 in a well known mauner. 17 is an
electric cable leading to and from a battery (not shown) constituting together with
the switch bar 20 and a coil 15 an insulated circuit. As shown in the present
instance this bar is moved to the right or left for the purpose of varying the coil
included in the circuit by the effect of variations of the level of the mercury in a
receptacle 21 by the medium of a diaphragm or float 18 resting on the surface of
the mercury in snid receptacle the float being transversely movable, in a branch or
chamber 22 of said receptacle. In the present instance this is represented as a
branch of a 3-way coupling (see Figure 3). The float is pivotally connected with
an arm 20 of the switch har suitably pivoted in a post 20" and said float is
counterbalanced by a weight 23. The construction and arrangement is such that
a variation in the level of the mercury moves the bar 20 over the switch board 16
to include within the electric current any one of the wires leading from the switch
board to the coils and thereby including the corresponding coil. By this means
the armature 14 is moved to the right or left according to the situation of the
coil by which it is magnetized. The switch board can be moved to the right or
left to vary the effective range of the switch bar by means of the screw having a
handle 16 as indicated. The mercury receptacle is attached to or connected with
the shield, so that any deflection of the latter from a right line will alter the
mercurial level and suitably regulate the admission of power to one or more of
the jacks by the action of the devices just described upon the valve 24 through the
medum of lever 11 and links 121 and 13.
The apparatus operates automatically to maintain a drift in one direction as

page_text: respects vertical or approximately vertical planes. To ad ut it to guar auto-
matically against deflection horizontally, mechanical devices, connecting the
shield and the completed part of the tunnel adapted to deflect the level of
mercury in the holder, would be requisite. Devices whereby a strictly horizontal
or sidewise deflection of the shield will tilt a mercury holder are not included in
the present application.
The particular devices for automatically controlling the amount of power exerted
at different points are not the gist of the invention which includes all devices
operated in substantially like manner by gravity to vary the amount of power
applied by changes in the direction of the shield movement. Thus it is obvious
that the particular form of valve or of mercury receptacle or of connecting devices
are immaterial. In some cases it is proposed to use an insulated pendulum as a
part of the electric circuit such pendulum being suspended in contact with a switch
board and adapted to vary the magnetizing coil in the circuit by its automatic
movements across the face of the board as indicated in Figure
Where shafts are to be sunk or tunnels driven through wet ground by means of
a movable shield it is very important that the water be effectually prevented from
entering between the shield and the shaft lining. Various means have been
proposed to effect this, but owing to the fact that the shield is made of plates
riveted together and never forms an absolutely true circle and that the shaft lining,
made of iron or steel castings also never makes a true circle, it is difficult to
secure an effective packing between the shield and shaft lining. To overcome
this difficulty for that portion of the shield containing the lining rings a true
bored out cylinder is adopted, whether of cast iron, cast steel or other material
and the iron rings are made true by casting facing strips on them, so that when
the ring is bolted up, these strips can be turned off to a true circle, which will
leave but the very little necessary clearance between them and the inside bored
surface of the shield. The clearance thus being very small and uniformn it is easy
to pack it successfully and cheaply by cellulose, or a soft wood or other suitable
material that will rest on the facing strips and, by expanding when wet, will make
efficient tight packing between the shield and lining.
In the drawings 26 denotes a strip fixed on a lining section and 27 a movable
packing. Said strips are narrow and require much less labour in making them
perfectly true than would be required for an entire section forming part of a ring
of uniform external diameter and as wide as a section. They also furnish convenient
supports for the packing. It is immaterial whether the strips be on the exterior
of the lining or on the interior of the shield provided the opposing surface be
correspondingly true. Where the projecting strips are on the inside of the shield
a Hap or packing made of pieces 28 of metal or other strong material, covered
with leather, rubber or other suitable material resting on the projections 26 on
the inside of the shield is sometimes used. These pieces of metal leaning against
the shaft or tunnel lining form the support for the flexible covering, which being
pressed tightly against the shaft lining by the pressure of the water or material
from above makes a tight joint or packing between the shield and the shaft or
tunnel lining. The pieces of metal simply rest in a groove 29 on the fitting strip
being held there by the leather or other covering which is riveted to them and to
the shield.
These pieces of metal are usually curved steel segments and are covered
with rubber, leather, canvas or other suitable material constituting a flap
surrounding the shaft or tunnel lining and closing the space between it and the
shield.
A flap of similar construction may also be used to make a stopping between the
outside of the shaft lining and the rock above the shield so as to prevent sand and
clay from descending in this space and interfering with the injection of cement
through holes in the shatt lining above the shield and to prevent the cement from
passing down between the shield and the rock thus cementing in the shield. This
use is only temporary, to allow the injection, through suitable holes in the

page_text: lining, into the space between the shaft lining and the rock above the shield of
bydraulic cement or sand and some solidifying solution, or other suitable material,
which material filling the crevices in the rock and the space between the rock
and the lining makes a tight joint and prevents the passage of water down around
the lining of the shaft and its entrance into the shaft below the lining and shield.
The flap is inserted in a recess in the lining segments of the shaft and when these
have passed up out of the shield said flap opens and is pressed out against the rock,
preventing the passage of sand or other material.
In driving tunnels through soft ground by means of a movable shield or caisson
pushed forward from the tunnel lining, it is customary to make the front of the
shield with doors which are lett open when the shield is in firm, dry ground, and
workmen go out in front of it and dig the ground throwing it back through these
doors, when it is again handled and thrown into the cars which convey it out of
the tunnel. When the shield is in soft ground some of the doors are closed and
the soft ground is allowed to come back through those which are left open, the
material being squeezed back by the forcing forward of the shield. The material
falls down onto the bottom of the shield and on the segmental lining of the tunnel,
and from there is loaded into the cars as before.
While this handling of the material is going on the lining segments cannot be
put in, but the act of lining and the movement of the shield and handling of
material alternate. The clay, mud and water coming into the shield where the
lining segments are put together renders that operation slow, difficult and
expensive, and the digging and handling of all the material by hand is also slow
and expensive.
In
By the adoption of the following devices which my correspondent has invented,
the speed of driving tunnels through soft ground can be very greatly increased and
their cost diminished. A double or annular shield is used as shown in the
accompanying drawing. In the annular space extremely powerful jacks or other
motors are placed and the shape of the shield so designed as to offer the least possible
resistance to piercing the clay, gravel or other soft material to be traversed.
the front of the shield, jets of water are placed worked under great pressure to cut
radially and loosen the mass of material compressed in front of the shield and
allow it more easily to be forced back through the centre tube. A centre tube
about ten feet less in diameter than the main shield is used so as to leave
sufficient space between them for handling and bolting up the segments of the
tunnel lining.
The centre tube has its forward end provided with doors indicated at 5". These
may be of usual construction and need not be particularly described herein. They
may be opened or closed as occasion requires as in existing shields, but the object
is to do the work of excavating largely by the power of the jacks, or other
propelling force, which will push the shield forward, forcing the soft material back
into the car, back of the annular working chamber, without interfering with the
work of putting in the segments of the lining, which goes on continuously in the
annular space or working chamber. The segments come in on a track on each
side of the centre tube and out of the way of the material passing from the
shield into the cars, so that not only is the work of excavating thus done by
machinery much more expeditiously and economically than by hand, but the work
of lining is greatly facilitated by being done in a comparatively clean chamber and,
by being made continuous.
The form of the front of the annular shield is such as to offer the least resistance
to its forward movement. When the ground becomes too firm to allow the shield
to be pushed through it, or when obstructions are met with, men can dig out in
front of the shield and remove the obstruction or excavate the ground in the usual
manner.
In the drawing 30 (Figure 2) denotes tracks or equivalent devices for bringing
in the sections of lining into the working space and 32 a track for the removal of
excavated material.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed as communicated to me
by my foreign correspondent 1 declare that what I claim is :
1. In combination a shaft sinking or tunneling shield, power mechanism for
advancing the shield and a gravity device to automatically vary the action of said
mechanism, substantially as set forth.
2. In combination a shatt sinking or tunneling shield, mechanism for advancing
the shield and devices for varying the action of the mechanism adapted to be
automatically operated by the departure of the shield from a desired direction
consisting of a valve and an electro-magnet and a circuit maker and breaker
adapted to be operated by gravity to make or break the magnetizing current,
substantially as set forth.
3. In a shaft sinking or tunnel driving apparatus the combination of the shield,
the living, the narrow fixed strips, said strips and the surface opposed to them
being made substantially true, and the expansible packing adjacent to the strips,
substantially as set forth.
4. In a shaft sinking or tunnel driving apparatus the combination of the strips,
the curved piece 28 supported thereon, elastic cover on said pieces and the tunnel
lining, substantially as set forth.
5. In a tunnel driving apparatus the shield having double walls joined at their
front and curved backwardly and inwardly and connected to a tubular part
provided with doors 5 to close the same at will, a track for moving a car in a
plane below said tubular part, a car to remove excavated material, and mechanism
for pushing the shield forward whereby the advance of the shield may be made to
automatically load the car, substantially as set forth.
6. In a tunnel driving apparatus a shield having double walls joined at their
foot, the inner wall being inclined inwardly and backwardly and connected to a
tubular part, hydraulic jacks or the like situated between said walls and a track
for carrying lining segments situated above the bottom of the shield and between
its walls, substantially as set forth.
Dated this 2nd day of January 1896.
WM. P. THOMPSON & Co.,
Agents.