Method and Apparatus for Driving Tunnels and other Subterranean Passages.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Method and Apparatus for Driving Tunnels and other Subterranean
Passages.
I, PETER KRAUS, of XIX Hermannstrasse 10, Vienna, Austria, 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 :-
The driving of tunnels and other subterranean passages in loose sand, gravel or
clay, is an exceedingly difficult and expensive operation on account of the great
difficulty of building in the tunnel lining in such strata. If, in addition, the strata
to be tunnelled are water bearing to a considerable extent the difficulties are
considerably increased. With the methods of tunnelling in sandy or gravelly strata
at present employed subsidences or falling in were hardly to be avoided, so that the
driving of a tunnel underneath buildings, canals &c. involved such technical
difficulties that in most cases such undertakings were abandoned on account of the
possible risks and the disproportionate costs involved.
The method which forms the subject of my present invention obviates the said
difficulties and risks, and enables the tunnelling in sandy, gravelly or clayey strata
to be effected much more expeditiously and cheaply than was heretofore possible.
The essential feature of the improved method consists in the employment of a
metal tubular shield, which is moved forward as the work of excavation proceeds
and which is so constructed that between its periphery and that of the excavated
tunnel a space is formed into which is introduced the concrete which is to form the
lining of the tunnel, and which, as the shield advances, is strengthened by the
introduction of iron rings or ring shaped frames which, according to the nature of
the strata, are either removed after the complete hardening of the concrete
lining, or are left permanently in position, or are further strengthened in exceptional
cases.
The accompanying drawings shew the arrangements of apparatus which I prefer to
employ for carrying out the said method of operating.
Fig. 1 shews a longitudinal section of a portion of a tunnel in loose aqueous
strata;
Fig. 2 is a modified arrangement for loose strata that do not carry much water;
Fig. 3 shews a front view of the rotating excavating frame;
Fig. 4 a cross section of one of its arms to an enlarged scale;
Figs. 5 and 6 shew portions of the shield with the sliding rollers.
The complete apparatus for carrying out the said method comprises the excavating
apparatus, the following cylindrical shield provided at its periphery with rollers;
the means for conveying away the excavated material; the arrangements for
introducing the concrete or cement into the gradually formed annular space between
the excavated tunnel and the shield; the means for consolidating the concrete; the
means for moving the shield forwards and backwards in the direction of the axis of
the tunnel; the motor engine for supplying the necessary motive power; and, when
necessary, the apparatus for working with compressed air.
The shiftable shield M is of tubular shape up to the concrete compressing
device J at its front end, having the configuration of the clear section of the tunnel
to be formed, and being made of such a length that the concrete which is forced
into the space between it and the excavated tunnel at the front end of the shield,
shall have become sufficiently hardened by the time that the rear end of the shield
has advanced to the point where the concrete is introduced to allow it to stand of
itself while the supporting rings or frames are being introduced. The requisite length
of the shield for this purpose will vary according to the nature of the strata the

page_text: rapidity with which this can be excavated determining the speed of advance of
the shield.
The walls of the shield must be sufficiently strong to effectually resist the
pressure of the strata, and are preferably made of angle iron or T iron laid side by
side parallel to the longitudinal axis and strengthened by transverse internal rings m,
or, for tunnels of large size or subject to considerable pressure, it is built up of a
suitably strong combination of iron plates and bearers.
The shaft A situated centrally in the shield, and driven by any suitable motor
engine, is made to penetrate at the front end into the face of the working; it carries
fixed thereon the arms a carrying plough like cutters, or they may be of the form
shewn at Fig. +, which cutters excavate the material from the face of the working
as the shaft A advances.
The arms a are preferably made of T iron (Fig. 4) to the web of which the
operating cutters s are attached by screws. The flanges of the T iron have bolt
holes formed in them so that when working in aqueous strata, a flat iron shield F
(Fig. 1) can be attached thereto so as to bear against the face of the working
behind the cutters, and thus prevent any undue falling in of the material.
As shewn in Fig. 3, the arms a can be strengthened by diagonal struts a¹, to
which may also be attached excavating cutters s as on the arms a. For facilitating
the fixing of the shield F, the arms a for machines working in aqueous strata are
preferably arranged at right angles to the shaft A, for the facility of fixing the
Hat shield F as at Fig. 1; in other cases, however, it is advisable to arrange them
in such manner that they are adjustably held by means of their stays a² in a more
or less inward sloping position relatively to the shaft A, as at Fig. 2; by this
means it is possible, by varying their inclination according to circumstances, to
increase or decrease the diameter of the cutting, and thus provide for a thicker or
thinner layer of concrete for the lining according to the nature of the strata that
are being cut through.
If the tunnel section is not required to be circular, but elliptical or oval, the
arms a must be arranged so as to shift inward and outward to and from the shaft A
according to the varying radius for which purpose they may be actuated by any
suitable arrangement of excentric guides. In such cases of course the tubular
shield M must also be made of a sectional configuration corresponding to that
which the tunnel is to receive.
The tubular shield M is made to follow up the excavating apparatus as this
advances, for which purpose the shield may be forced forward by screws,
hydraulic pressure or compressed air, such forward motion being facilitated by
the rollers w provided at its periphery. These rollers have their axes carried in
the webs of the angle or Tirons W₁ forming the periphery of the shield; Fig. 5
shews an arrangement for T iron, but preferably the arrangement with angle
iron shewn at Fig. 6 is employed, where each roller axis is provided with
separate bearings, so that no frictional resistance is caused by the ends of the
axes butting against each other as would occur in the arrangement at Fig. 5.
For protecting the bearings against contact with the concrete lying over them
they are covered in with caps as shown.
The tubular shield M is securely guided in the required direction in 'its
forward motion, firstly by the accurately guided driving shaft, which is advanced
in the direction of the axis of the tunnel by a screw or other means, and
secondly by the pressure applied against the outer closed end of the shield.
By applying at each of the points of the periphery where the propelling
power is made to act either an equal or an unequal amount of power it is
possible to make the shield and excavating apparatus advance either in a
straight line or in any desired curve and either horizontally or in an upward
or downward inclined direction.
In the arrangement shewn at Fig. 1, the propelling power is supposed to be
compressed air, which is made to act in pipes p against the periphery of the closing
disc P.

page_text: In this case any required deviation of the shield from the straight and
horizontal line is obtained by varying the pressure in the several pipes by means of
differently loaded valves placed in the communications of the pipes with the
reservoir for compressed air.
As shewn at Fig. 1, the concrete lining of the tunnel formed round the shield M
is protected against falling in up to the face of the working; if however a falling
in is also to be anticipated at the face of the working, the disc-shield F is fixed to
the arms a as already described. This shield has a central hole o through which
the shaft A passes, and through which the material excavated also passes into the
interior of the tubular shield, while the remaining part of the face is effectually
protected by the shield against falling in.
The material passing through the opening o into the shield M is conveyed
backwards through conduits G or chain buckets into the finished part of the tunnel,
from which it is then conveyed to the outside by trucks or other means.
In proportion to the advance of the excavation and the corresponding advance of
the shield M, concrete is forced through the pipe L by means of either hydraulic
pressure or compressed air, into a circular pipe K, extending round the front of the
shield from which pipe it issues through suitable openings into the space existing
between the excavated tunnel and the outer surface of the shield M.
For compressing the concrete as it is forced in, a compressing apparatus is
arranged close in front of the working which consists essentially of an annular
plate, which receives a to and fro stamping motion for acting on the end surface of
the concrete.
2T
As shewn there is arranged an annular box J fixed to the shield M in front of
the working face, the inner circumference of which is of such a size as to coincide
with the outer surfaces of the rollers 1 of the shield M. In this box, which is also
provided with rollers at its outer periphery which bear against the excavated
tunnel, is the annular stamping plate i which is acted upon by strong springs and
is alternately drawn back by means of wire ropes passing over guide rollers, and
is forced forward by the springs. The wire ropes are for this purpose passed
centrally through the springs, which are situated at distances of from 60 c.m.
to 90 c.m. apart and are suitably attached to the annular plate i, and after being
led over guide rollers into the interior of the shield M, they are all united to a
single wire rope, so that by alternately pulling and rapidly releasing the latter, the
before described strong stamping motion is imparted to the plate i. The said
motion of the hauling rope may be effected either by hand or by any suitable known
mechanism.
By the above described action of the annular plate i, the concrete, as it
enters from the pipe K will be stamped into a solid mass forming an effective
strong lining to the tunnel.
As shewn on the drawing the box J is formed with slots on its inner periphery
so that any concrete that may be carried backward by the stamping plate i, will
escape through the said slots 3 into the interior of the shield M whence it will be
conveyed away together with the excavated material.
In order to prevent the solidifying concrete from penetrating between the
rollers wand thus prevent their rotation, the shield M is rendered capable of moving
slightly backward as well as forward.
When using compressed air for forcing the shield forward, this may be effected
by, producing alternations of pressure in the conduit pipes p by means of suitable
valve arrangements, so that the shield may have a to and fro motion imparted to it
during the time that the concrete is hardening, such motion being continued until
the concrete is sufficiently hardened to retain the smooth cylindrical surface
imparted to it by the rollers. The concrete lining, which is of course quite soft at
the front end of the shield M, will be sufficiently hardened at the rear end of the
shield, where it is uncovered by the advance of the latter, to sustain unaided the
pressure of the surrounding strata for a length of from 10 to 13 c.m. during the time

page_text: requisite for the supporting rings of TI or U iron to be fixed against the inner
periphery of the uncovered portion.
In order to enable these rings to be rapidly placed in position, they are
constructed of separate curved sections corresponding in configuration to that of
the tunnel, which sections are secured together at the joints by flanges and screw
bolts.
The supporting lining thus fixed in behind the advancing shield M may serve
either as temporary or permanent support of the concrete lining. If the pressure
to which the lining is subjected is such that this will effectually withstand it, the
said rings are removed after the complete hardening of the concrete, and are fixed
again in a more forward position. If on the other hand the concrete is not
sufficiently strong by itself to withstand the pressure the iron lining is left standing
either along the whole length of the tunnel or only at those parts where the support
is more particularly required; or the rings may be strengthened or even removed
and replaced by others of a stronger nature if required.
In cases where owing to the presence of large bodies of water, it is necessary to
operate with compressed air within the tubular shield M, the compressed air
chambers may either be formed within the shield itself, or they may be formed by
fixing sheet iron diaphragms having many holes to the flanges of the supporting
rings in the finished water tight part of the tunnel so as to form the requisite
compressed air chambers.
As the tunnelling proceeds these chambers would then be shifted forward so as
to follow the advancing shield.
It will be seen from the above description that the improved method of tunnelling
in clayey, sandy gravelly or aqueous strata, can be carried out without any risk of
breaking down or subsidence. By entirely dispensing with wooden tubbing and by
rendering machinery applicable for effecting the work, this will be carried out
much more rapidly and at less expense than was possible with the means heretofore
employed.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is
1. A method of driving tunnels in clayey, sandy gravelly or other loose or
aqueous strata consisting in the use of a tubular metal shield that is forced forward
close up against the face of the working as the excavation of the latter proceeds,
such excavation being effected to a size exceeding that of the tubular shield, so as
to leave an annular space between the excavated tunnel and the shield, into which
space concrete is forced and compressed, so as to form a lining to the tunnel, which
lining is supported by metal rings as it is left free by the advancing shield, sub-
stantially as described.
2. For carrying out the method of operating set forth in the preceding claim, the
use of a tubular metal shield M the outer periphery of which is provided with rings
of rollers w for facilitating the advance of the shield, the latter being made to
contain the excavating machine, the means for supplying the concrete to the
aunular space, and the appliance for compressing the concrete therein, substantially
as described.
3. In combination with the shield referred to in the preceding claims, the use of
an excavating machine consisting of arms a to which are attached the inter-
changeable cutting tools s, and which are fixed to or adjustably carried by a
revolving shaft A arranged centrally in the shield M, the arms being provided with
bolt holes for the attachment of a flat sustaining shield F when required sub-
stantially as described.
4. In combination with the arms a referred to in the preceding claim the use of
a flat shield F for sustaining the face of the working against falling in, which
shield has a central opening through which the shaft A passes, and through
")

page_text: which the excavated material passes into the interior of the shield M, substantially
as described.
5. In combination with the tubular shield M referred to in the preceding claims,
the use of an annular pipe K having openings through which the concrete forced
into it through the pipe L passes into the annular space between the shield M and
the excavated tunnel, and an appliance for compressing the concrete in such space,
consisting of a tubular box secured to the shield M close against the working,
in which box is an annular plate i that is caused by wire pulling cords i¹ and
springs to exercise a stamping action upon the concrete as it enters the annular
space, so as to consolidate it, substantially as described.
6. In the concrete compressing apparatus referred to in the preceding claim, the
provision of rollers on the outer periphery of the annular box J such rollers being
made to bear against and support the excavated periphery of the tunnel so as to
prevent it from falling in until by the advance of the shield M it receives support
from the concrete.
1000
ABEL & IMRAY,
Agents for the Applicant.