Construction of Submarine Bridges.
Year: 1896

page_text: Date of Application, 11th Apr., 1896
Complete Specification Left, 6th Jan., 1897-Accepted, 20th Mar., 1897
Communicated from abroad by THE CHANNEL BRIDGE AND RAILWAY
COMPANY LIMITED, of 69 Rue de la Victoire, Paris, France.]
Construction of Submarine Bridges.
I, HAROLD IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the
County of London, Chartered Patent Agent, do hereby declare the nature of this
invention to be as follows:-
This invention relates to the construction of submarine bridges for .crossing
rivers, estuaries or channels, such, for example, as the Straits of Dover. The
bridge presents two lines of rails, each of very wide gauge such as 30 metres, with
a similar width between them. These rails are laid at a level of about 12 metres
under low tide level, so as not to interfere with navigation, and rest on continuous
longitudinal lattice girders all tied together transversely and resting on strong
trestles. Each trestle consists of two inclined hollow piles connected at the top
by a cross girder and diagonally stayed together. There are two sets of these
trestles one for each railway line, placed at intervals apart which may be about
60 metres. On each line of rails runs a carriage consisting of a strong framing
as wide at the bottom as the rail gauge and narrowing to a suitable width at
the top to constitute a carriage for passengers or goods, this upper part being at
a suitable height above high tide level. The carriage, which may be about
200 metres long, is utilised for the erection of the bridge in the following manner.
The front part of it carries a machine for levelling the foundation for the trestles,
this machine consisting of a sharply toothed roller which is mounted on a vertical
framing that can he lowered until the roller meets the bottom of the channel.
The roller being then caused to revolve, while the frame carrying it is moved
to and fro longitudinally and transversely, the toothed roller grinds the face of
the bottom rock to form a flat bed for the hollow pile. This being done for a
pair of these piles, a complete trestle consisting of the pair of piles and their cross.
ties is lowered from the carriage, and the top of the trestle is then connected to
the longitudinal girders by fresh lengths of girders which are also lowered from
the carriage. The hollow piles may be provided with packing material on their
bases so that when they are in position there is a watertight joint at the bottom.
The pile can then be emptied so that workmen-can descend and effect anchorage
to the rock. In the Straits of Dover, however, this may not be necessary as a flat
foundation can readily be obtained, and the pile can be filled with concrete, the
weight of which in addition to that of the superstructure will render the trestles
practically immovable.
Dated this 11th dar of April 1896.
ABEL & IMRAY,
Agents for the Applicant.

page_text: Construction of Submarine Bridges.
I, HAROLD IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in
the County of London, Chartered Patent Agent, 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 :-
This invention relates to the construction of submarine bridges for crossing
rivers, estuaries or channels, such, for example as the Straits of Dover.
The construction of the said bridge is shewn on the accompanying drawing, in
which
Figure 1 shews a longitudinal elevation of the same, and
Figure 2 shews a cross section.
The bridge presents two lines of rails rr each of very wide guage, such as
30 metres, with a similar width between them, the rails being carried directly by
corresponding lines of girders A supported on metal piles B arranged as trestles,
and secured to the rocky bed of the waterway. These piles B are formed tubular
preferably inclined in the transverse direction, for the purpose of affording a
widened base and increasing their stability; they are connected at top by a
transverse girder C to which they are also connected at intermediate points by
bracings a a, the number of which will depend upon the height of the piles. These
supports which are fixed in the manner to be presently described, are secured at
their upper ends to the longitudinal girders A on which are fixed the rails on which
run the carriages.
The arrangement of the trestle supports for the bridge and the construction of
the bridge itself may of course vary according to the locality where the bridge is
to be constructed; in the present instance it is assumed by way of example that
the waterway to be crossed is the Straits of Dover, and the present invention also
relates to special means for preparing the bed of these straits for receiving the
supports of the bridge.
The bridge has, as before stated, two lines of rails of about 30 metres guage
and the same width of space between, each line of rails being supported by a
trestle pile structure as above described, placed in line with each other, the
transverse girders C being extended right across the two sets so as to tie them
firmly together.
In constructing this submarine bridge, the first sections next the shore are
erected by the ordinary means employed for working at depths of from
12 to 15 metres below the water level, the top surface of the bridge being
kept at 12 metres below low water line, in order to give sufficient draught over
it for navigation. The shore section having been constructed, there are placed
upon the rails the two carriages X X, which had been previously constructed on
shore, and of which the upper platforms are connected together by a temporary
floor so as to form a platform of about 200 metres in length, that is to say, the
length of the carriages, and 75 metres in width.
The weight of the carriages and the connecting floor will render the travelling
scaffolding thus formed of perfect stability, whatever may be the condition of the
sea, and this scaffolding is then employed, in gradually advancing, for fixing
successively in position the farther sections of the bridge.
For this purpose the floor of the scaffolding is formed in front with a strong
overhanging wood structure, which constitutes the jib of a crane, and, enables
suspended working platforms to be erected at about 60 metres in front of the
carriages which distance is about equal to that between the successive pile
supports B of the bridge.
Figure 3 shews to a somewhat larger scale one of these suspended platforms.

page_text: The preliminary dressing or excavating of the bed is effected from these
platforms, for fixing the bases of the tubular piles of the trestle supports.
When mere surface dressing of the rocky bed has to be effected, this is carried
out by means of special machinery, as shewn at Figure 3 in side view and Figure 4
in front view. It consists mainly of a metal cylinder e capable of rotating on a
horizontal axis, and provided with steel sharp edged pyramidal projections so that
in rotating it will abrade the rocky bed on which it is pressed. This cylinder.
is carried at the lower end of a vertical frame D fixed at its upper end to a
travelling winch F which can travel both in a longitudinal and transverse direction
upon a scaffolding E erected at a suitable height above the water. By means of
this carriage the abrading cylinder can be raised or lowered at will and its pressure
upon and movement over the rocky bed be regulated, so as to level and smooth
the latter over the required extent of surface.
The rotation of the cylinder c can be effected by means of a wire rope trans-
mission driven by a steam engine on the platform, or by a dynamno d enclosed in a
watertight casing e fixed at the lower part of the frame D as shewn.
The rotation of the cylinder c in the water will ensure its being kept clear. Its
If
size and form will depend upon the nature of the rocky bed to be acted upon.
necessary diamonds, similar to those used in diamond drills, can be employed in
place of steel points for acting on hard rocks.
By means of this apparatus the comparatively soft surface of the rocky bed of
the channel will be dressed by abrasion.
As the bed of the Dover Straits presents at the point between Dover and Calais
a comparatively smooth and only slightly inclined surface, the formation of a level
base for a pile structure by the machinery described will ouly require the
destruction of a comparatively small volume of rock, and can be effected with
perfect precision.
The rock surface having been thus prepared, the two pile trestles or structures
previously fitted together, and which do not weigh more than 200 to 250 tons are
lowered on to them by means of powerful winches arranged in front of the
carriages, which serve to bring the said structures forward. These are guided
in their descent by means of vertical guides fixed to the carriages, so that the
placing thereof in position can be effected with the greatest precision.
While the structures are still held by the lowering apparatus, the longitudinal
girders are fitted on them by means of other cranes for securing the lowered pile
structure to that previously fixed.
Each girder only weighs about 80 tons, and the accurate placing in position
thereof on the piles is insured by the provision of grooves or sockets formed on the
heads of the latter for their reception.
The girders are properly guided into their position by the aid of divers; after
they have been properly fixed and the rails secured thereon the carriages with the
scaffolding are at once advanced so as to bear with their weight thereon, and thus
insure the stability of the new structure, after which the stays securing the piles
together and to the previously built part of the bridge are fixed by divers, while
at the same time the rocky bed is prepared as before described to receive the
next section, and so on, the work proceeding continuously.
For still farther insuring the stability of the bridge the tubular piles may be
filled in with concrete to the extent of from 80 to 100 cube metres, weighing
from 200 to 240 tons, but the compact and fissureless nature of the rock forming
the bed of the channel, and the perfect levelling of the surface obtained by
the above described process will generally enable the following process to be
employed for increasing the stability.
The lower end surface of the tubular pile is provided with a thick caoutchouc
washer, attached thereto before lowering, so that on this washer being pressed on
to the dressed surface of the rock by the weight of the pile, a practically
water-tight joint will be formed, enabling the interior of the pile to be
pumped out.

page_text: The rock within the pile can then be excavated or drilled either to receive
a mass of concrete or masonry extending up into the pile, or for fixing keying
devices of any kind, by which the piles are secured to the rock.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The herein described method of constructing submarine bridges on rocky beds,
consisting in lowering on to the previously prepared bed, pile structures or trestles
previously built up into a single piece, which testles are then connected together by
transverse and longitudinal girders.
2. In the construction of a submarine bridge such as referred to in the first
claim, the use of a scaffolding on wheels, running on the part already constructed of
the bridge, and which may consist of the carriages that are ultimately to run on
the bridge which serves both to convey the parts of the structure to the place
where it is to be erected to prepare the rocky bed for the reception thereof, and to
place such parts in position upon the prepared bed, the said scaffolding being for
this purpose made with parts overhanging the carriages, and provided with suitable
cranes and other gear for lowering the trestle structure for the next section
in advance directly on to its bed, substantially as described.
3. In the construction of a submarine bridge such as referred to in the first
claim, the method of dressing the rocky bed of the waterway by means of an
abrading cylinder having hard sharp projections which as the cylinder revolves
attack the surface of the rock, substantially as described.
4. Actuating the abrading cylinder referred to in the third claim by means of
a dynamo contained in a water-tight casing on the lower end of the vertical frame
carrying the cylinder, substantially as described.
5. Regulating the vertical and horizontal movements of the abrading cylinder
referred to in the third and fourth claims by means of a winch capable of
longitudinal and transverse motion on the platform of a scaffolding erected above
the water level, substantially as described.
6. In the construction of a submarine bridge such as is referred to in the first
claim the method. of utilizing the weight of the carriages and scaffolding for
increasing the stability of the sections of the bridge as soon as they have been
lowered into position, substantially as described.
7. In the construction of a submarine bridge such as is referred to in the first
claim, producing a water-tight joint between the bases of the tubular piles and the
prepared rocky bed, and after discharging the water from the pile, excavating or
drilling the rock within it for the purpose of keying the pile to the rock, either by
masonry or concrete, or by other means, substantially as described.
Dated thie 6th dox of Tonnery 1907
ABEL & IMRAY,
Agents for the Applicant.