Improved Wall or Lining for Shield Tunnelling, and for Shaft Sinking.
Year: 1896

page_text: Improved Wall or Lining for Shield Tunnelling, and for Shaft
Sinking.
I, GEORGE HENRY DUNLOP, of 139 Bridport Street South Melbourne, in the
Colony of Victoria, Engineer, do hereby declare the nature of this invention to
be as follows:-
This invention relates to an improved wall or lining for shield tunnelling by the
adoption of which it is not necessary to follow the shield with metal cylinders or
masonary or other similar material as is now usually done. In my system I
employ the ordinary shield and follow it up with a strong wooden lining which is
built up in sections or segments and provided with continuous lines of horizontal
struts strong enough to form resistance posts or bearers for the hydraulic rams
by which the shield is forced forward.
The aforesaid wooden linings which form either a temporary or a permanent
lining or wall to the excavation or tunnel is built of suitable lengths and in
sections to form a complete ring of the requisite diameter, somewhat after the
form of centerings, the lagging on outside being supported by strong segmental
ribs at each end and when necessary at their centre whilst between said ribs are at
least as many longitudinal struts as there are hydraulic jacks employed and such
struts are arranged to lie end to end, each line being continuous for the purpose
before stated. The whole of the woodwork is securely spiked and bolted together
or otherwise firmly secured.
Said wood linings may either be left at their position and be covered with the
necessary thickness of concrete to complete the tunnel or the linings are put
together in such a manner that the greater portion of the timber such as tho
segmental ribs may he removed and for the latter purpose the meeting ends of
the lagging may overlap each other, also when so desired the segmental ribs may
be made of cast or wrought iron. As an alternative in place of the concrete the
tunnel proper may be formed of wooden blocks fitted and built together in a
suitable manner.
When tunnelling to prevent distortion of the lining through heavy pressure
or running ground a "sett" or framing of timber is used between the ribs or
laggings to resist any such undue pressure.
This system will in some instances be applicable when the shield is not used
and further it may be applied to shaft sinking.
Dated this 10th day of August 1896

page_text: COMPLETE SPECIFICATION.
Improved Wall or Lining for Shield Tunnelling, and for Shaft
Sinking.
T, GEORGE HENRY DUNLOP, of 139, Bridport Street, South Melbourne, in the
Colony of Victoria, Civil 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 invention relates to an improved wall or lining for "shield " tunnelling and
for shaft sinking the invention being applicable also to ordinary tunnelling. By
the adoption of this method in shield tunnelling it is not necessary to follow the
shield with metal cylinders or masonry or other similar material as is now usually
done as I employ the ordinary shield and follow it closely with strong wooden
lining of the outer form of the tunnel or shield built of sections or segments
forming rings and provided when requisite with continuous lines of horizontal
struts strong enough to form resistance posts or bearers for the pressure of the
hydraulic rams by which the shield is forced forward. The rings or consecutive
lengths of lining are built either partly or wholly within the tail or rear end of
the shield or close following the rear end of the shield.
The aforesaid wooden linings may form either a temporary or a permanent
lining or wall to the excavation or tunnel or they may be left at their position
and be covered with the necessary thickness of concrete or masonry cle to com-
plete the tunnel or the linings are put together in such a manner that a great
portion of the timber such as the segmental ribs can be removed before building
such masonry lining. When tunnelling to prevent distortion of the lining through
heavy pressure or running ground a "sett" or framing of timber is built between
the ribs or laggings to resist any such undue pressure.
In the attached drawings, Fig. I is an end view of the wood lining or wall and
shewing the "sett" in position and Fig. 2 a longitudinal sectional view of two
connected lining or wall rings, one of which shows the laggings complete and
also shewing the "sett." Fig. 3 is a similar view to Fig. 2 but shewing the
segmental linings provided with longitudinal flanges which may take the place
of the struts. Fig. 4 a part longitudinal section of the linings when the ends of
laggings overlap. Fig. 5 a part end view of linings showing the rings strengthened
by intermediate segments and Fig. 6 is also a part end view shewing the key
piece employed for closing the joint of the type of linings shewn in Fig. 3.
Figs. 7 and 8 shew tapering "key" segments to facilitate removal of the ribs shewn
in Fig. 4.
As shewn in the drawings, each "ring" or length of tunnel lining in its simplest
form consists of the circumferential laggings and their supporting ribs, a a being
the ribs each composed of a suitable number of segments formed of one or more
layers or plies of wood and bb the boards or laggings supported at or near their
ends by said ribs and when in position forming the outer tunnel lining. Tho
laggings may be double, forming a double layer of laggings breaking joint so that
the longitudinal joints in each of these inner and outer layers are covered by
laggings of the other layer. care the struts or thrust blocks, one or more of
which is placed opposito each ram of the shield to bear and distribute the pressure
when shoving the shield also the struts form braces for the segments. In shield
tunnelling with lining as shown in Fig. 2 when the thrust block c c are not used
the head of the ram will be so formed as to bear on the ends of the laggings when
shoving the shield. d d (Figs. 2 and 5) are segments either temporary or per-
manent, securely wedged between the struts e and thus forming a complete or part

page_text: These
ring intermediate to the ribs a. Said segments d may only be required when the
laggings or ribs are being unduly strained. The "sett" is composed of sill e cap el
and legs and it is built within the linings when further strength is required
or to provent deformation of the linings until the vacuity left by the shield outside
of the laggings has been filled by grouting or by the closing-in of the unsupported
earth at the sides of the tunnel. This sott may be extended by additional struts
to further strengthen large tunnel linings. ff (Figs. 3 and 6) are longitudinal
flanges which may be used to form connecting pieces between the end rib segments
also they may be used with, or take the place of, the thrust blocks cc.
flanges may be either as deep radially as the rib and laggings as in Fig. 6 or as
deep as the rib only; the laggings in this case being continuous around each ring.
9 is a key consisting of a piece either rectangular or tapering of the length of
the ring for keving plates or portions of rings having the longitudinal flanges f f
or where the shield is too small to allow the ring to be completed with ordinary
segments alone.
In tunnels where the ribs a a are removed wholly or for
part of the ring before the concrete or other masonry is built in, the rib at one
end of each ring is smaller in diameter than the rib at other end and the laggings
overlap as shown in Fig. 4, throughout the whole ring or for such part as the
ribs are to be removed and in this system the concrete or masonry is placed in
position as shown by dotted lines m in Fig. 4 in lengths equal to the ring lengths
and ending close to the smaller rib and which latter and the adjoining large rib
may be removed after the laggings are covered with concrete or masonry, the
laggings of the unlined ring being temporarily supported by the end of the
laggings of the concreted ring which they overlap. One of the segment pieces a
of each complete rib may be of a tapering form as shewn in Figs. 7 and 8 to
facilitate removal where the rib part only of segments of each ring are to be
removed the remaining portion which will usually bo the lower portion may have
the laggings butt jointed as shewn at Figs. 2 and 3.
In order to prevent water or earth from getting through the lining, the joints
throughout may bo packed with soft-wood strips, tarred-folt or other material as
is done in lining tunnels with cast iron, and the outer surface of linings may be
covered with sheet metal or tarred-felt; and the longitudinal joints between
Inggings may be caulked. The laggings are spiked to the ribs where the ribs are
not to be withdrawn and the thrust blocks cc and longitudinal flanges ff are
spiked to the ribs or secured to them with wrought iron timber dogs, iron straps,
with cleats, or other usual timber fastenings. Wedges h (Fig. 2) for if necessary
adjusting the ring lengths and afterwards for facilitating the withdrawal of the
thrust blocks may be placed at the end of each block. The rib segments of
adjoining rings are bolted together as shown in Fig. 2, also the longitudinal
flanges of each ring are bolted together (see Fig. 3) when such flanges are used.
The whole or part of each rib may be of cast or wrought iron, preferably of
channel section, where the ribs are to be partly or wholly withdrawn, the lower
part of the ribs may be of iron and the upper portion of wood and in this case
the wooden portion may be removed and metal portion may remain.
This system may in some instances be applicable when the shield is not used
either where the ground is sufficiently firm to stand unsupported for the length
and for the time necessary for inserting a ring of lining or where the ground is
wholly or partly supported by compressed air or by temporary timbering or other
lining.
This system of lining may be applied to shaft sinking in a similar manner to
tunnelling either with or without a shield or "box" in advance of the lining.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I
claim is:-
(1) In shield tunnelling a wall or lining consisting of wooden rings built in

page_text: sections or segments each composed essentially of ribs as a laggings as b sub-
stantially as herein described and shewn in the drawings.
(2) A wooden wall or lining for tunnelling composed of ribs as a and laggings
as band struts as a having if necessary a strengthening "sett" as e, e¹, e, Hanges
asf and segments as d all secured together and arranged substantially as herein
described and shewn in the drawings.
(3) A wooden wall or lining for tunnelling of the type herein specified having
the laggings as b (Fig. 4) so arranged as that they overlap as and for the purpose
herein described.
Dated this Sixth day of April 1897.
G. H. DUNLOP,
W. Lloyd Wise,
46 Lincoln's Inn Fields, London, W.C.,
Agent for the Applicant.