U.S. patent application number 10/591101 was filed with the patent office on 2007-08-16 for apparatus and method for flood defence.
Invention is credited to John Charles Macintosh Forrest.
Application Number | 20070189854 10/591101 |
Document ID | / |
Family ID | 32088752 |
Filed Date | 2007-08-16 |
United States Patent
Application |
20070189854 |
Kind Code |
A1 |
Forrest; John Charles
Macintosh |
August 16, 2007 |
Apparatus and method for flood defence
Abstract
An apparatus for flood defence comprises a plurality of slab
units (3) rotatable about an axis (4) between a lowered position
and a raised position which slab units (3) are substantially
balanced about the axis (4). The slab units (3) form a path when in
their lowered position, and form a flood barrier when in their
raised position. When the slab units (3) are in their raised
position, they form a seal with the base (5) of the apparatus and
removable boards are placed in the gaps between adjacent raised
slab units (3) and between a raised slab unit and an abutment.
These boards are then clamped to seal the gaps.
Inventors: |
Forrest; John Charles
Macintosh; (Southampton, GB) |
Correspondence
Address: |
FAY SHARPE LLP
1100 SUPERIOR AVENUE, SEVENTH FLOOR
CLEVELAND
OH
44114
US
|
Family ID: |
32088752 |
Appl. No.: |
10/591101 |
Filed: |
February 28, 2005 |
PCT Filed: |
February 28, 2005 |
PCT NO: |
PCT/GB05/00738 |
371 Date: |
January 22, 2007 |
Current U.S.
Class: |
405/107 |
Current CPC
Class: |
E02B 7/44 20130101; E02B
3/102 20130101 |
Class at
Publication: |
405/107 |
International
Class: |
E02B 3/10 20060101
E02B003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 4, 2004 |
GB |
0404954.0 |
Claims
1. An apparatus suitable for flood defence comprising at least one
slab unit rotatable about an axis between lowered and raised
positions, the at least one slab unit comprising at least part of a
barrier for water retention when in its raised position,
characterized in that the at least one slab unit is substantially
balanced about the axis.
2. The apparatus as claimed in claim 1, including a base, the at
least one slab unit being rotatable relative to the base.
3. The apparatus as claimed in claim 2, including sealing means for
forming a seal between the at least one slab unit and the base when
the at least one slab unit is in its raised position.
4. The apparatus as claimed in claim 2, wherein the base comprises
a channel into which a part of the or each slab unit rotates
downwardly upon deployment.
5. The apparatus as claimed in claim 1, including sealing means
between a said slab unit and an adjacent abutment or slab unit.
6. The apparatus as claimed in claim 3, wherein the sealing means
between a said slab unit and an adjacent abutment or slab unit
forms a continuous seal with the sealing means between the at least
one slab unit and base when the at least one slab unit is in its
raised position.
7. The apparatus as claimed in claim 3, wherein when at least one
said slab unit is deployed in its raised position, a significant
portion of the height of the slab unit is positioned downwardly of
the axis whereby hydrostatic pressure deployed from water being
retained by the slab unit compresses the seal.
8. The apparatus as claimed in claim 7, wherein when said slab unit
is deployed, substantially one third of the height of the slab unit
is positioned downwardly of the axis.
9. The apparatus as claimed in claim 5, wherein the sealing means
between a said slab unit and an adjacent abutment or slab unit
comprises at least one hinged or removable portion.
10. The apparatus as claimed in claim 9, including clamping means
for clamping the hinged or removable portion against at least one
seal.
11. The apparatus as claimed in claim, wherein the removable
portion comprises a removable board.
12. The apparatus as claimed in claim 1, wherein the slab unit
comprises different portions with different densities for balancing
the slab unit when the slab unit is not centrally positioned
relative to the axis.
13. The apparatus as claimed in claim 12, wherein at least one
portion of the slab unit with a different density includes at least
one counterweight.
14. The apparatus as claimed in claim 1, including means to bias
the at least one slab unit towards the raised position.
15. The apparatus as claimed in claim 14, wherein the biasing means
comprises a movable weight.
16. The apparatus as claimed in claim 1, wherein the slab unit
forms at least part of a paved way when in its lowered
position.
17. An installed apparatus for flood defence as claimed in claim 2,
wherein a substantial portion of the base projects above ground
level so that the apparatus provides a first level of flood defence
when the or each slab unit is in its lowered position and the
apparatus is arranged to provide a higher second level of flood
defence when the or each slab unit is in its raised position.
18. The apparatus as claimed in claim 1, including at least one
strut which is adjustable in length for supporting at least one
said slab unit in its raised position.
19. The apparatus as claimed in claim 1, including locking means
for locking at least one said slab unit in its lowered
position.
20. A method for flood defence comprising the step of: rotating at
least one slab unit about an axis from a lowered position to a
raised position so as to comprise at least part of a barrier for
water retention when in the latter position, and characterized by
the step of: substantially balancing the at least one slab unit
about the axis.
Description
[0001] The present invention relates to an apparatus and method for
water retention for use mainly, but not exclusively, for flood
defence.
[0002] Domestic and commercial properties built in low lying areas
may be susceptible to flooding, particularly if they are built on a
flood plain. Existing flood defences to protect such properties may
comprise permanent bunds or walls of fixed height but these can
prevent access across the line of defence and can be unsightly.
Temporary defences immediately adjacent to domestic properties are
usually provided in the form of sandbags and the sealing up of
doors and windows. However, these defences confine the inhabitants
to their homes during the period of the flood and are severely
limited by the height of the sand bags and the strength of doorways
and windows to resist water pressure. Other temporary defences, on
a larger (non-domestic) scale, comprise a variety of systems such
as flexible tubes filled with water, stone filled gabions, strutted
and sheet materials covered with an impermeable membrane, and are
sited alongside river banks to protect larger areas of flood
sensitive land. All such temporary devices have the dual
disadvantages of only protecting a small height of flood and being
labour intensive to install and dismantle.
[0003] WO 01/71099 discloses a system for flood defence having a
channel shaped foundation in which is stored a barrier hinged to
the foundation and folded along two internal longitudinal hinges. A
shore plate covers the folded barrier and is also hinged to the
foundation. To erect the barrier, the shore plate is folded out and
the barrier is then folded out to form a vertical structure with
the shore plate locked to the lower of the two internal hinges of
the barrier to support the barrier. This system requires the weight
of the shore plate and the barrier to be supported as they are
rotated and folded out and the barrier needs to be temporarily held
whilst the shore plate is locked to it to support the barrier. The
erection of such a barrier would be time consuming.
[0004] An object of the present invention is to provide an
apparatus and method for flood defence which alleviates at least
one of the above mentioned problems.
[0005] According to one aspect of the present invention there is
provided an apparatus suitable for flood defence comprising at
least one slab unit rotatable about an axis between lowered and
raised positions, the at least one slab unit comprising at least
part of a barrier for water retention when in its raised position,
characterized in that the at least one slab unit is substantially
balanced about the axis.
[0006] By making the at least one slab unit substantially balanced
about the axis, the slab unit can be rotated manually into its
raised position without having to rely on a powered driving means
which may, for example, require either electrical or hydraulic
power supplies or a combination of both. The slab unit may be
finely balanced for movement by fingertip action. The slab unit may
weigh several tonnes and can be balanced in such a manner that it
can be adjusted to be lifted with one hand from the lowered (e.g.
horizontal) position to the raised (e.g. vertical) position. Thus,
only a single average strength adult is required to raise or lower
the slab unit although two people should be used to conform to
safety requirements. The use of gravity in the manner of
counterbalancing the slab employs a force of nature to assist
manual erection. Hence countermeasures to resist gravity, such as
props, are not necessarily required.
[0007] A flood barrier of a substantial height can thus be quickly
erected/taken down by use of the apparatus. The apparatus forms at
least part of an active defence when the or each slab unit is in
its raised position. In addition, the view from any property being
protected by a flood barrier comprising the apparatus is only
temporarily obstructed whilst the or each slab unit is in its
raised position.
[0008] The apparatus can be used for a range of applications for
the protection of domestic, commercial, and public buildings,
industrial sites and flood sensitive land whether from threat by
river or sea and in both rural and built-up areas and provides a
lack of unnecessary inconvenience to the owner of the property/land
to be protected.
[0009] The apparatus provides a permanent demountable defence.
[0010] The apparatus may include a base wherein the at least one
slab unit is rotatable relative to the base.
[0011] The apparatus preferably includes sealing means for forming
a seal when the at least one slab unit is in its raised position.
The sealing means may form a seal between the at least one slab
unit and the base when the at least one slab unit is in its raised
position.
[0012] There may be at least one abutment adjacent the slab unit.
The sealing means may be arranged to form a seal between the slab
unit and the adjacent abutment when the slab unit is in its raised
position.
[0013] The apparatus preferably includes a plurality of said slab
units rotatable about said axis. The sealing means may be arranged
to form a seal between adjacent slab units when the slab units are
in their raised position.
[0014] When a slab unit is deployed in its raised position, a
significant portion of the height of the slab unit may be
positioned downwardly of the axis whereby hydrostatic pressure
deployed from water being retained by the slab unit compresses the
seal. In order that water pressure alone keeps the seal(s) closed
naturally, substantially at least one third of the height of the
slab unit is positioned downwardly of the axis. This determines the
extent of the effective active height possible without other
measures being introduced (for example propping) to resist
imbalanced water forces.
[0015] The pressure of water retained by a raised slab unit
maintains a positive pressure against seals both between the slab
unit and the base (e.g. horizontally) and between a slab unit and
an adjacent slab unit or abutment (e.g. vertically) and employs the
forces of nature in a positive and natural manner to ensure the
safe closure and effectiveness of the water seals. Thus sealing
countermeasures such as props which have to be tightened a set
amount to ensure that a seal resists water and remains closed, is
not necessarily required.
[0016] In order that the slab units may be raised individually, the
means of sealing between a said slab unit and an adjacent abutment
or slab unit preferably comprises at least one removable portion.
The removable portion may comprise a removable board. There may be
wedging means for urging the removable board against at least-one
seal. The wedging means may comprise a scissor action device which
is able to provide a wedging action. The device may comprise any
one of a variety of clamping methods such as crossed metal tapered
flats in "scissor" form, or loose plates held on captive bolts and
tightened with captive nuts.
[0017] The sealing means between a said slab unit and an adjacent
abutment or slab unit preferably forms a continuous seal with the
sealing means between the at least one slab unit and base when the
at least one slab unit is in its raised position.
[0018] There may be at least one strut or prop for supporting at
least one said slab unit in its raised position. The strut may be
adjustable in length and may be used to tighten the slab unit
against the seal between the slab unit and the base when the slab
unit is in its raised position. The strut may be removable.
[0019] The apparatus may include locking means for locking at least
one said slab unit in its lowered and/or raised positions.
[0020] The apparatus provides a raised flood barrier by unlocking
the at least one slab unit and simply rotating the at least one
slab unit to its raised position, locking the at least one slab
unit in its raised position, inserting the sealing means between
the at least one slab unit and abutments and, if necessary,
inserting struts. This operation can be conducted in a matter of
minutes by unskilled labour and unskilled labour just need to be
shown once how to erect/lower the flood defence.
[0021] The slab unit may comprise different-portions with different
densities and this enables the slab unit to be balanced when the
slab unit is not centrally distributed relative to the axis. This
may be achieved by the slab unit having means such as a bracket, or
rack, or racking holding or supporting at least one balancing
weight. An appropriate number of unit balancing weights may be
included in order to achieve fine balancing of the slab unit. To
enable the slab unit to be lifted with one hand, a weight may be
moved along a beam attached to the slab unit until the slab unit
tilts. The position of the weight on the beam indicates the weight
of the slab unit on the opposite side of the axis. A suitable slab
unit may be approximately 3 to 5 metres long and 1.5 to 3 metres
wide. In a preferred embodiment for a domestic property, the slab
unit is approximately 3 metres long, 1.5 metres wide and 15
centimetres thick. This is a typical size for ease of transport to
the site and erection. The slab unit may include an edge frame
which may provide for the inclusion of a suitable decking and
surfacing. In tests, erection of the apparatus to a secure state of
flood defence using a slab unit approximately 3 metres long took
unskilled labour only 3 minutes to complete.
[0022] In order to vary the height of a flood barrier when the slab
unit is in its raised position, the centre of gravity of a slab
unit may be varied by, for example, rearranging the slab unit's
balancing weight(s), their support brackets and/or the space
occupied by the weight(s).
[0023] The slab unit of the apparatus preferably forms at least
part of a paved way when in its lowered position. The paved way may
comprise a pavement or footpath for pedestrians and/or a road for
vehicles. Thus, the apparatus provides a dual function of providing
a paved way when the at least one slab unit is lowered and
providing at least part of a barrier for water retention when the
at least one slab unit is raised.
[0024] The apparatus for flood defence may have a substantial
portion of the base projecting above ground level so that the
apparatus provides a first level of water retention for flood
defence when the or each slab unit is in its lowered position and
the apparatus is arranged to provide-a higher second level of water
retention for flood defence when the or each slab unit is in its
raised position. The first level for flood defence is a passive
defence and may comprise at least part of a shallow raised bund
around part or all of the building(s) or land to be protected. The
apparatus can be landscaped into the land or the grounds of a
building such as a garden of a home. There would be no obstruction
to the view to the grounds of the building from a ground floor
window when the apparatus is providing a first level for flood
defence.
[0025] The base may comprise a channel which can act as a drainage
duct. The base may comprise a mounting or upstand extending into
the channel which supports the or each slab unit for rotation. The
channel may have an integral downwardly projecting foundation
portion.
[0026] The apparatus can have a full service life of 50 years and
has cost advantages in relation to maintenance and to the number of
people required to erect/lower the defence.
[0027] According to another aspect of the present invention there
is provided a method for flood defence comprising the step of:
[0028] rotating at least one slab unit about an axis from a lowered
position to a raised position so as to comprise at least part of a
barrier for water retention when in the latter position, and
characterized by the step of:
[0029] substantially balancing the at least one slab unit about the
axis.
[0030] The apparatus and method requires no untried components.
[0031] An embodiment of the present invention will now be
described, by way of example only, with reference to the
accompanying schematic drawings, in which:
[0032] FIG. 1 is a schematic layout of a flood defence
incorporating the apparatus according to a typical embodiment of
the invention;
[0033] FIGS. 2A and 2B are schematic cross-sections of the
apparatus illustrating the relationship of the active and passive
defence measures of a typical embodiment of the invention;
[0034] FIG. 3 is a cross-sectional view of the apparatus in a
lowered position;
[0035] FIG. 4 is a sectional view taken along lines 4-4 of FIG.
3;
[0036] FIG. 5 is a plan view of a frame for a slab unit of the
apparatus;
[0037] FIGS. 6A and 6B are cross-sectional views of the slab unit
taken along lines 6A-6A and 6B-6B of FIG. 5, respectively;
[0038] FIG. 7 is a cross-sectional view of the apparatus in a
raised position;
[0039] FIGS. 8 and 9 are an elevational view and a sectional view,
respectively, of the apparatus of FIG. 7;
[0040] FIG. 10 is a detail of a fine balancing device for the
apparatus; and
[0041] FIG. 11 is a sectional view taken along lines 11-11 of FIG.
10.
[0042] Referring to FIGS. 1, 2A and 2B of the accompanying
drawings, a domestic building 1 such as a house has a manual flood
defence comprising the apparatus 2. The apparatus 2 comprises a
plurality of slab units 3 rotatable about a horizontal axis 4
relative to a base 5 forming a channel structure 9 which can act as
a drainage duct. The slab units 3 are shown in solid lines in a
horizontal lowered position and in dotted line in a vertical raised
position. The slab units 3 are laid out as a path in a straight
line between two permanent abutments 6 or buttresses and are
parallel to an embankment wall 7 of a river 8. Further apparatus 2'
extends from each of the abutments 6 at any angle to the apparatus
2 as part of the flood defence.
[0043] FIGS. 2A and 2B illustrate the apparatus involved as an
active/passive defence sited in relation to existing ground and
floor levels to be protected. FIG. 2A indicates the benefits of
employing a combined passive defence and active defence for
resistance to flooding having a passive height (P) of the base 5
protruding above the ground and an active height (A) of the raised
slab unit 3 above the base 5. The level of the base 5 or foundation
may be sited such that a bund comprising the base 5 does not impair
the view from the downstairs window of the house. The maximum
height of a flood defence consisting of a combined active height
(A) and a passive height (P) requires the floor 57 of the drainage
duct 9 of the base 5 to be sited at least 15 cm below the level of
the floor 58 of the building 1 or land to be protected, so as to
ensure a minimum facility to collect and pump away any penetrating
water. FIG. 2B illustrates the defence for a building or land where
only an active defence is provided such as where a roadway is sited
at natural ground level. In this situation, the slab units 3 are at
existing or required ground level when in their lowered positions.
The drainage duct 9 provides an automatic water collection facility
for any water penetrating the defence or rising through the ground
behind the defence and the collected water can then be pumped
away.
[0044] Referring to FIGS. 3 and 4, with the slab unit 3 in the
horizontal, lowered position, the channel structure 9 has a dry
side walls portion 10, a wet side wall portion 11 and a bottom
portion 12. Within this channel structure 9 sit a plurality of
metal constructions comprising identical sets 13 or mounts which
are spaced at half the slab unit length and uniformly along the
length of the channel structure 9. Each set comprises a pair of
stub columns 14 supporting a bearer beam 15 which supports a
bearing bracket 16 at one end and a locking block 17 is affixed to
the other end. The slab unit 3 is supported in the horizontal
position by the locking block 17 and by a bearing 19 housed within
the bearing bracket 16. All such sets 13 in the construction are
joined together by continuous foundation angles 20 bolted both to
the stub columns 14 as well as the bottom portion 12 of the channel
structure 9. Along the foundation angle 20 is affixed continuously
a horizontal `b` shaped hollow seal 21. The seal 21 is secured to
the foundation angle 20 by bolting at regular intervals a seal
fixing channel section 22. The assembly of bearing bracket 16 and
bearing 19 carried by the bearer beam 15 extends within a housing
23 (see FIG. 5) in the thickness of the slab unit 3. At each set 13
position, the slab unit 3 is held in a locked position by a locking
pin 18 secured to each locking block 17 and turned by a key (not
shown) shaped uniquely to match the lock assembly. The slab unit 3
is finely balanced about the axis or hinge line 4 by the
incorporation of appropriate unit balancing or counterweights 24
placed within the thickness of the slab unit 3 at the outermost
edge facing the threat of flood.
[0045] Referring to FIGS. 5, 6A and 6B, the slab unit 3 has an edge
frame formed by L-shaped members 25 and within which is a
sub-assembly of members acting in support of a decking 26 which
may, for example, comprise an asphalt top on a waterproof membrane
or a layer of light concrete. Across the width of the slab unit 3
span two separate pairs of opposed bearing support angle members 27
to which is fixed a plate 28 on which the bearing 19 is fixed.
[0046] Parallel with the length of the slab unit 3 are back to back
angle members 29 running the full length of slab unit 3 (except
between the bearing support angle members 27) and supporting the
counterweights 24. The counterweights 24 may be of precast concrete
and be shaped to fit the angle members 29. Intermediate channel
members 30 for supporting the decking 26 are parallel to the
bearing support angle members 27 and span between the back to back
angle member 29 facing the L-shaped member 25 parallel and furthest
from the axis 4.
[0047] Within the housing 23 formed by the opposed bearing support
angle members 27 is located a strut 31 capable of being extended a
defined length. The strut 31 comprises a tube 32 (fitted with a
turnbuckle 42 as shown on FIG. 7) sliding snugly within a larger
diameter tube 33. Tube 33 is closed at one end and is permanently
secured at the closed end to the bearer beam 15 by a pin hinge 34.
In the stowed position the free end of tube 32 is held securely
horizontal by a clip 35, secured in turn to the bearer beam 15.
[0048] In order to form an active defence the slab unit 3 is
unlocked from each of the locking blocks 17 using a key provided
for this purpose. Referring to FIG. 7 and considering all activity
takes place from the side of the construction furthest from the
threat, the finely balanced slab unit 3 is raised to the vertical
position and pushed away (towards the threat) at the top so that
the toe of the slab unit 3 impinges on the horizontal seal 21. This
push is continued until a latch 37 or locking means attached to a
stub column 14 adjacent the rotated slab unit 3 engages with the
L-shaped member 25 at the toe of the slab unit 3, thus securing the
slab unit 3 in the vertical position. The free end of each of the
extending struts 31 are then pulled out of the clips 35 and raised
up. Tube 32 is pulled out of tube 33 until holes 36 in both tubes
are coincident. Pins 38 are then inserted through the coincident
holes 36 to lock the strut 31 to the required length and spring
clips 39 inserted in holes in the pins to ensure the security of
the fixing.
[0049] Referring to FIG. 8, the free end of the strut 31,
comprising a small plate 40 connected to the tube 32, is then
placed within the two sides of a projecting channel shaped bracket
41 on the face of the slab unit 3 and secured with a pin 38 and
spring clip 39. The turnbuckle 42 is then rotated either way to
ensure the strut 31 is properly secured and engaged with the top of
the slab unit 3 such that the junction between adjacent slab units
3 is aligned correctly.
[0050] Referring to FIGS. 8 and 9, in order to form the vertical
seal between adjacent slab units 3 a sealing board 43 is inserted
in each gap 44 between adjacent slab units 3. Each gap 44 is formed
between opposing L-shaped members 25 forming part of the edge frame
of each adjacent slab unit 3. Each opposing L-shaped member 25 has
an angle member 45 fitted therein so that the combined L-shaped
member 25 and angle member 45 forms a channel. The sealing board 43
is the length of the width of the slab unit 3 and the width of the
sealing board 43 is such that it can be admitted into the gap
between the opposing angle members 45. The sealing board 43 is
placed into the gap 44, rotated so that one face 56 of the sealing
board 43 faces the returns on the two opposing angle members 45 and
lowered until the board 43 is stopped by a toe plate 50 fitted at
the bottom end of each perimeter angle member 25. The bottom
portion of the sealing board 43 faces the horizontal seal 21 and
the board 43 is brought into contact with the returns on the two
opposing angle members 45. The contact surfaces of the sealing
board 43 are fitted with seals 46 along the length of the board 43
and are aligned with corresponding seals 46 on the returns on the
opposing angle members 45. The sealing board 43 is fitted with
several clamping devices 47 whereby a loose, but captive, flat
plate 48 is tightened by a hand operated butterfly nut 49. The
sealing board 43 is tightened against the opposing angle members 45
by turning the flat plates 48 so that they engage with the face of
the angle members 45 on the opposite side to the contact surfaces
facing the sealing board 43. The butterfly nuts 49 are then turned
so as to press the plates 48 firmly against the angle members 45
and clamp the sealing board 43 into position so that the vertical
seals 46 of the sealing board 43 and angle members 45 are clamped
together, and so that the seals 46 are also clamped against the
horizontal seal 21 in order to effectively plug the gap between the
opposing angle members 45.
[0051] The gap between each abutment 6 (see FIG. 1) and an adjacent
slab unit 3 are sealed in the same way and when the last of the
clamping devices 47 is fixed the defence is completed.
[0052] Any water which seeps between adjacent raised slab units 3
or a raised slab unit 3 and an adjacent abutment 6 is collected in
the channel structure 9 which acts as drainage duct from where it
can be pumped away.
[0053] Restoring the defence to the horizontal position involves
the identical procedure in the reverse order of activity. When not
in use, the sealing board 43 is stowed in the channel structure 9
under the slab unit 3 when the slab unit 3 is in its horizontal,
lowered position and the sealing board 43 is retrieved from there
when the active defence is to be formed again. Apart from the
sealing board 43 all fittings required for the defence are
permanently connected to the sets 13, thus requiring no additional
materials or equipment to be delivered in the period of erection
prior to the onset of a flood. All components required for
erection, dismantling and safety during a flood are fixed or stored
under the slab units such that they are always available for use
except, obviously, for the key to unlock the slab unit 3 from the
locking block 17.
[0054] It is an inherent requirement of the apparatus that each of
the separate slab units 3 are finely balanced to give a slight
imbalance towards the end (which swings down) facing the flood
threat. To achieve this effect a preferred embodiment uses a mobile
weight independently of the counterweights.
[0055] Referring to FIGS. 10 and 11, the weight 51 is bolted to a
metal plate 53 which is fitted with two lugs 54 which each have a
threaded hole 55. The plate 53 is clamped to the intermediate
channel members 30 which are fixed within the framework of the
L-shaped angle members 25. Clamping is achieved by tightening a
bolt 52 through the threaded hole 55 in the plate lug 54 against
the return on the channel member 30. The position of the weight 51
is determined when, using the optimum number of counterweights 24,
the slab unit 3 is in complete (finger lift) balance in the
horizontal position. The adjustable position of the mobile
balancing weight 51 provides full flexibility for balance.
[0056] The slab units 3 can have any required finish. In a typical
embodiment, each slab unit 3 is approximately 3 metres long, 1.5
metres wide and 15 centimetres thick. The dimensions of L-shaped
members 25 are 150.times.90 mm, and the deck 26 used is 6 mm thick.
The bearings 19 comprise standard units available from normal
suppliers. The channel 9 is formed from reinforced concrete. The
sealing board 43 is of high density plastic and has the dimensions
1500.times.150.times.20 mm.
[0057] The depth of the footing below the bottom portion 12 of the
channel structure 9 is determined from a site investigation of the
permeability of the soil and its strength characteristics to
prevent the apparatus 2 from sliding or tilting.
[0058] Whilst a particular embodiment has been described, it will
be understood that various modifications may be made without
departing from the scope of the invention. For example, a variety
of structural materials may be used for ease of construction,
suitability in corrosive ground conditions, long life maintenance
free characteristics and the economics of the installation. The
vertical seal between adjacent slab units or a slab unit and an
adjacent abutment may comprise a board housed within the space
afforded by the edge detail of juxta-opposed slab units or a slab
unit and abutment and fixed by hinging or other means so as to be
positioned in conjunction with seals in order to form a waterproof
joint. Also, additional measures to supplement the apparatus may be
used such as pumps, which may be portable, to pump out any leakage
around the seals via a continuous ducting system on the dry side of
the dam. Sumps may be strategically placed for the use of the
portable pumps to keep the flow of water in the duct at an
acceptable level. The size of the duct of the channel structure 9
is selected to suit the requirements of ancillary works for the
apparatus, together with the need to accommodate other services
such as electrical/communication services and pipework.
[0059] The size of the apparatus may be adjusted to suit factors
such as sloping ground, required height of the barrier and the
length of the paved way. All support structures for the slab units,
their bearings and strutting devices, together with any ducting,
are subject to individual workings and site conditions.
* * * * *