Improved Method of Tunnelling and Apparatus connected therewith.
Year: 1890

page_text: Date of Application, 17th May, 1890
Complete Specification Left, 2nd Feb., 1891-Accepted, 7th Mar.. 1891
PROVISIONAL SPECIFICATION.
Improved Method of Tunnelling and Apparatus connected therewith.
I, JOHAN RUDOLF LILLJEGVIST, 32, Victoria Street, Westminster, Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in tunnelling and is particularly applic-
able in water-bearing soil and rock under water.
The excavating shield consists of a funnel-shaped chamber and a cylindrical or
corrugated outer casing, the whole stiffened by a number of solid diaphragms.
The rear of the outer casing forms a cylindrical flange overlapping the front edge
of the tunnel which is built up inside the shield.
When passing through water-bearing soil or rock under water the rear of the
funnel-shaped chamber has a spoutlike continuation the top rim of which is
arranged so as to leave a sufficient margin between it and the surface of the water
allowed to enter to the level of the top of the circular rear opening of this chamber.
The operations of excavating and building the front of the tunnel are in that
case carried on in compressed air the pressure of which must be such as to keep
the surface of the water in the spout at the desired level.
A band of indiarubber is fixed on the inside of the flange overlapping the front
edge of the tunnel or some other suitable material is inserted between it and the
outside of the tunnel in order to ensure an airtight joint as far as possible.
The shie'd is pushed forward and the loose or loosened material forced into the
funnel-shaped chamber by hydraulic jacks fixed between the diaphragms and acting
against the front edge of the tunnel.
The material filling the funnel is then removed at the rear end either by hand or
by a bucket-'adder driven by water or air under pressure.
If rock is met with the bucket-ladder (if any) is removed, the rear opening of
the funnel closed by a movable door and the spout removed.
In the centre of the door a ball and socket joint is arranged for the hollow drills
required for boring in the rock or large boulders that might be met with. The
drills may thus be directed to any point of the front opening of the funnel.
When a hole has been drilled and the core removed but whilst the drill is still in
the hole, the charge with fuse and wires for firing are inserted in the hole and the
drill removed.
The charges must be small so as not to injure the cutting edge of the shield and
when firing takes place the men retire for safety behind a bulkhead arranged in
the tunnel.
After a sufficient amount of rock has been loosened the spout is fixed again, the
door removed and the material taken out in the manner above described.
Dated this 17th day of May 1890.
COMPLETE SPECIFICATION.
Improved Method of Tunnelling and Apparatus connected therewith.
I, JOHAN RUDOLF LILLJEGVIST, 32, Victoria Street, Westminster, 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 :-
This apparatus is designed for use in all kinds of subaqueous tunnelling as well
as tunnelling through water-bearing strata such as wet clay, sand, gravel etc.
The apparatus or shield consists of a funnel-shaped chamber A (see Fig. 1) formed
by steel or iron plating rigidly connected to the outer casing B by a number of solid

page_text: diaphragms C. The outer casing may be either cylindrical or corrugated as shown
by Fig. 2. The latter shape might be adopted for the better placing of the
hydraulic rams actuating the movement of the shield.
These rams D are placed between the diaphragms and the cylinders are firmly
fixed to the outer casing, the pistons acting against the edge of the tunnel or its
lining. The rear end of the outer casing forms a cylindrical flange E overlapping
the front of the tunnel. During the work of excavating such material as contains
water the funnel-shaped chamber is provided with a spout-like continuation F..
When water enters the spout the operation of excavating and building must be
carried on in compressed air, the pressure of which ought to be about equal to that
of a column of water measured from the top of the circular opening to the surface
of water outside the tunnel. The horizontal edge of the spout must be arranged
so as to leave a sufficient margin for the fluctuations of the water-level. To
prevent too much air escaping between the front of the tunnel and the overlapping
flange E a band of indiarubber is fixed on the inside of the latter or some other
suitable material is inserted in the opening and renewed when necessary.
Assuming the material to be gravel and the excavation to be made under a river-
bed the method of working the shield would be about as follows:
The shield is pushed forward by the hydraulic rams acting against the lining of
the tunnel, the gravel in front of the shield being thus forced into the funnel-
shaped chamber. When the latter is sufficiently full the gravel is removed either
by a movable bucket and ladder arrangement or by hand labour.
The gravel in the funnel-shaped chamber will assume its natural angle of slope
and care must be taken to push the shield forward or stop the excavation as soon as
the line of slope touches the cutting edge of the excavating shield as indicated by
Fig. 1 (a), otherwise gravel would be excavated from outside the line of tunnelling
and no useful work would be done.
If rock or large boulders be met with necessitating blasting operations the rear
opening of the funnel-shaped chamber is closed by a movable door G Fig. 3 and
the spout removed. In the centre of the circular door a ball and socket joint is
arranged for the hollow drills required for boring. The drills may thus be directed
to any point of the cutting edge. When a hole has been drilled and the core
removed but whilst the drill is still in the hole, the charge with fuse and wires for
firing are inserted in the hole and the drill removed.
After a sufficient number of holes have been drilled and charged the men retire
for safety behind a bulkhead arranged in the tunnel and firing takes place in the
usual manner. The charges must be small so as not to injure the cutting edge.
After a sufficient amount of rock has been loosened the spout is fixed again the door
is removed and the material taken out in the manner above described. The machinery
in the tunnel may be driven either by compressed air or water under pressure.
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° For tunnelling a funnel-shaped shield with cutting edge.
2. In subaqueous tunnelling or tunnelling through water-bearing strata the
combination of the funnel-shaped shield and the spout arranged in such a manner
that the water is prevented by the air pressure entering the tunnel and that at the
same time the material may be removed through the spout.
3° In tunnelling through rock or large boulders under water the combination of
the funnel-shaped shield and a movable door provided with a ball and socket joint
supporting drills.
4° In subaqueous tunnelling the combination of the funnel-shaped shield with
spout and a movable bucket and ladder for removing the material.
J. R. LILLJEGVIST.