Improvements in the Construction of Subterranean Tunnels and in Machinery therefor.
Year: 1898

page_text: Date of Application, 20th Dec., 1898-Accepted, 25th Feb., 1899
Improvements in the Construction of Subterranean Tunnels and in
Machinery therefor.
I, WILLIAM JAMES EAMES BINNIE, Civil Engineer, of 10, Holland Park Man-
sions, W., Holland Park Gardens, W., 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:—
My invention relates to the construction of subterranean tunnels_formed with
a lining of concrete or other similar substance, & by my invention I am enabled
to excavate a tunnel by means of a shield, without the expense incurred when
the tunnel is lined with a metal lining, & I am enabled to construct a lining
of concrete capable of withstanding any strain tending to deform it, & capable
of resisting the necessary pressure required to thrust forward the shield, as I
shall-describe referring to the accompanying drawings, Fig. 1 being a longitu-
dinal & Fig. 2 a cross section of the tunnel on A A Fig. 1.
The shield I employ is in its main features, similar to the well-known "Great-
head shield," but differs therefrom in the construction of the hydraulic rams,
which are placed round its circumference, & whereby it is propelled as will
hereafter appear.
Having got my shield into position against the face of earth it is required to
cut through, & having erected an adequate support behind the shield to take
the thrust of the rams, [Nos. 1 to 5 Fig. 1 & Nos. 1 to 8 Fig. 2] as will appear
I proceed to cut away the earth in front of the shield & to pass it out through
the shield, & operating the rams I then thrust the shield forward one unit (this
amount being about one foot six inches, if convenient, & I shall assume this to
be the amount the shield travels in one operation.)
Within the tail of the shield [B, Figs. 1 & 2], & concentric therewith I then
erect a ring or lining [C, D, E, & F, Fig. 1 & C, D, E, F, G, H, Fig. 2] of
a less radius than the shield, the difference in radius between the inside of the
shield & the outside of this ring being equal to the thickness of the concrete
lining it is proposed to adopt. This ring which is constructed of boiler plate of
any suitable thickness with internally projecting flanges to strengthen it & to
enable it to be bolted to the next succeeding ring, being the width of one unit
or 1 foot 6 inches.
Between the tail of the shield & this ring, I then shovel in concrete, the rams
being retracted as will be further explained, & operating the rams I first com-
press the concrete, which compression goes on till a pressure of about 60 lbs.
per square inch is reached, after which the concrete does not materially compress
further, & is able to bear a pressure sufficient to enable the rams to thrust the
shield onwards one unit. The pressure is then maintained until a fresh ring has
been bolted to the last, [as shown in Fig. 1] the rams are then retracted, more
concrete is shovelled in, & the process repeated. When about 60 of these rings

page_text: have been erected & about 90 ft. of the tunnel has been made, it will be found
that the first portion of concrete is perfectly set and the first ring can be taken
down and re-erected as the GIst, only 60 rings being thus required to complete
the whole tunnel. Of course I do not bind myself to this number of rings,
any number more or less which is found necessary & sufficient is to be used
according to the nature of the work to be dealt with.
By this method of working the concrete is compressed between the internal
ring & the external tail of the shield while still green, & thus a very solid
concrete is ultimately secured, filling the space also formerly occupied by the
skin of the shield & doing away with the necessity of grouting behind the tunnel
lining.
The rings are formed in segments, [C, D, E, Fig. 1, & C, D, E, F, G, H
Fig. 2 so that they can be bolted together in situ & can be readily removed
from one end of the set of rings to the other, & I find it convenient to make
the top segment C Fig. 2 of such size, that, when the lower segments are removed,
it falls down on to a roller track L Figs. 1 & 2 by means of which track the top
segment can be transported from one end of the set of rings to the other as its
turn comes to the used at the front.
I may also so arrange the railway track or tracks M Figs. 1 & 2 in the tunnel
that they are carried in short lengths by the rings themselves, that is the
tracks are laid in 1ft. 6 inches lengths each length being carried by a ring, thus
obviating the laying of fresh rails in the proximity of the shield as the shield
advances.
There may be any desired number of rams on the shield and they are provided
with pressure heads 1"-8" Fig. 1, 1 & 5 Fig. 2 adapted to fit the space between
the tail of the shield & the ring, so that the pressure heads compress every por-
tion of the concrete contained between the tail of the shield & the rings, allowing
only such clearances as are necessary.
The shovelling of the concrete commences at the bottom, the lower pressure
heads Nos. 4" 5", & 6" Fig. 2 being retracted till they just reach the forward
end of the ring last bolted up, thus forming a box or mould into which the
concrete can be shovelled. The next higher pressure heads Nos. 3 & 7 Fig. 2
are then retracted till they in turn reach the forward edge of the ring, when the
next higher part is filled up & so on till all is filled except the portion behind
the top pressure head. No. 1 Figs. 1 & 2. The top pressure head No. 1"
Figs. 1 & 2 is then retracted until space is left between it & the front of the
ring to shovel in the requisite concrete between the top of the ring & below the
top of the tail of the shield. The whole space left cannot be filled up as the
concrete will form a heap with the slanting forward surface due to the angle of
repose. The result will be that the top pressure head will, from the beginning,
be rather in the rear of the lower ones, & to admit of this the top plunger or
plungers must be made of rather longer travel than is necessary for the rest.
Also it is adviseable to face the top plunger with wood N, Fig. 1 as, in com-
pressing the concrete, the bottom part of the pressure head comes first into
contact with the lower advance edge of the slope of repose & stones might get
wedged under the pressure head & damage the ring. When a wooden face is
used, such stones will merely sink into the wood.
Having now particularly described & ascertained the nature of my said inven-
tion & in what manner the same is to be performed, I declare that what I
claim is:-
1. In the formation of a subterranean tunnel with a shield lining the tunnel
with concrete in a semifluid condition which concrete is supported by a temporary
internal core so that the semifluid concrete can take the pressure required to
drive the shield forward.
2. The method of constructing a subterranean tunnel lining the same with
green concrete which subsequently sets, substantially as described.

page_text: TWO ON DICcenery therefor.
3. In the construction of a tunnel by means of a shield lining the tunnel with
semi-fluid concrete so that the pressure of the rams will cause the concrete to
flow into the space previously occupied by the tail of the shield, whereby the
operation of grouting is dispensed with.
Dated this 19th day of December 1898