Note: Descriptions are shown in the official language in which they were submitted.
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54-219/003.526
FACING SYSTEM
The present invention relates to a facing system
for a frictionally stabilised earth structure.
British Patent No. 1069361 of Henri Vidal describes
earth structures wherein stability is achieved by
compacting successive layers of earth into frictional
contact with stabilising members. These members
stabilise the mass virtually completely by frictional
forces, both between the reinforcements and the adjacent
fill particles and between those particles and the
remainder of the fill. The stabilising members are so
spaced that the frictional forces are transmitted
throughout the fill and tension generated in the
stabilising elements opposes significant horizontal
movement of the fill particles. A preferred type of
reinforcement in these structures is an elongate flat
steel strip which in use lies in the fill with its flat
faces horizontal and with one end attached to a facing
panel.
This earth stabilisation technique enables the
structure to have at least one substantially vertical
face and such a face will normally be clad with a facing
system which, in order to conform to small movements
created by the above compacting procedure and to
accommodate the small elastic or even permanent
movements of the structure permitted by the
stabilisation technique, is preferably flexible in the
plane of the face. In general, such flexibility can be
provided by facing panels attached to the stabilising
members. British Patent No. 1324686 discloses such a
facing system in which the facing panels have
interlocking side edge portions arranged to permit
relative displacement between adjacent panels whilst
preventing earth particles from passing between adjacent
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panels. With this known interlocking arrangement the
facing panels must all lie in the same place since it is
not possible to connect adjacent panels at an angle to
each other.
It has been proposed in European Patent Application
No. 0 345 077 (not published as of the priority date of
this application) to form a facing which is angled or
curved when viewed in plan. This is achieved by
slightly turning a facing element relative to an
adjacent element, but the design of the elements is such
that the maximum amount of "turn" as between any two
elements is limited to a few degrees. It is not
therefore possible to achieve for example a right angle
bend in the facing.
Viewed from one aspect the invention provides a
facing system for a frictionally stabilised earth
structure, comprising an assembly of facing panels
having means for attachment to frictional stabilising
members embedded in the earth of said structure, the
facing panels having side edge portions for connection
to laterally adjacent facing panels, each such side edge
portion having a lateral projection and a lateral recess
respectively engaged with a lateral recess and a lateral
projection of the adjacent facing panel, at least some
laterally adjacent facing panels being assembled in the
same plane as each other and at least some laterally
adjacent facing panels being assembled at an angle to
each other, the assembly of the facing panels in both
cases being substantially sealed against passage of
earth between adjacent panels.
Viewed from another aspect the invention provides a
kit of facing panels for assembly with each other to
form a facing of a frictionally stabilised earth
structure, each facing panel having means for attachment
to at least one frictional stabilising member embedded
in the earth of said structure, and a side edge portion
for connection to a laterally adjacent facing panel,
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each such side edge portion having a lateral pro;ection
and a lateral recess respectively for engagement with a
lateral recess and a lateral pro;ection of the adjacent
facing panel, the side edge portions being configured
such that ad;acent facing panels are engagable either in
the same plane as each other, or at an angle to each
other, the engagement in both cases being substantially
sealed against passage of earth between adjacent panels.
The invention also provides a frictionally
stabilised earth structure having such a facing system,
and frictional stabilising members attached to said
facing system and embedded in the earth of said
structure.
Using facing panels in accordance with the
invention it is possible to form a facing having therein
one or more right angle or other angle bends, as viewed
in plan, whilst the facing panel design also permits the
more conventional arrangement in which adjacent panels
lie in the same plane. Since the side edge portions of
the facing panels are configured such that laterally
adjacent facing panels may be connected to each other at
any desired angle between the coplanar and at least a
perpendicuIar arrangement, the facing may be designed to
follow many possible profiles in plan view. The
increased versatility of the facing panels thus provides
greater choice to a designer of frictionally stabilised
earth structures.
The side edge portions of the facing panels are
preferably configured such that adjacent panels are
engagable with each other with their rear faces turned
towards each other with an angle of less than 180 (e.g.
a right angle) therebetween, or with their front faces
turned towards each other with an angle of less than
180- (e.g. a right angle) therebetween. Such an
arrangement means that a facing can be bent in both
directions as desired, producing either "external" or
"internal" corners.
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A facing will normally comprise a series of
superimposed rows of facing panels, and it is possible
for the panels of one row to follow a profile in plan
view which differs from the profile of the row below.
Thus in a preferred form of the invention, the facing
comprises a plurality of superimposed rows of facing
panels, wherein a lower row includes two laterally
adjacent facing panels arranged with their rear faces
turned towards each other with an angle of less than
180- (e.g. a right angle) therebetween, and a row
superimposed on said lower row includes two laterally
adjacent facing panels arranged with their front faces
turned towards each other with an angle of less than
180 (e.g. a right angle) therebetween, whereby an
exposed area of earth is defined generally rearwardly of
said two facing panels of the lower row and generally
forwardly of said two facing panels of the superimposed
row. Such an arrangement advantageously provides
planting areas for vegetation whilst using relatively
simple plate- or slab- like facing panels.
There are many possibilities for the plan view
profile of each row of facing panels, providing the
panels of a superimposed row are located either directly
above or rearwardly of panels in the row below. Thus
the size of an exposed area of earth may be limited to a
rhombus or a square having sides all approximately equal
to the lateral dimension of the panels, or the exposed
area may take a variety of parallelogrammatic or
rectangular shapes with dimensions approximating to
multiples of the lateral dimensions of the panels. More
complicated shapes are possible in view of the ability
of a facing panel to be "bent" either forwardly or
rearwardly relative to an adjacent panel.
With the arrangement described above, there will be
some facing panels with a forward side edge portion
supported by an adjacent facing panel and a rear side
edge portion supported by the earth backfill below.
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Where larger exposed areas of earth are provided, both
side edge portions of certain facing panels may be
supported on the backfill. It may then be desired to
provide the facing panels with foundation pads to spread
their weight on the backfill.
The earth backfill behind the facing panels will
normally be compacted to ensure good frictional contact
with the frictional stabilising members. It may not be
easy to establish plant growth on compacted backfill and
it may be desired to place topsoil on the backfill.
Alternatively, a hole of e.g. 35cm diameter may be
drilled in the backfill to receive the roots of a shrub,
tree or other plant or plants, with suitable soil being
provided around the roots.
In order to maintain a seal between the side edge
portions of the facing panels in the different possible
positions thereof, preferably the side face of each
lateral projection is formed as a convex curve, and the
slde face of the lateral recess of the adjacent facing
panel with which said projection engages is formed as a
complementary concave curve. This enables the gap
between the connected side edges of the panels to be
kept to a minimum whatever the angle between the panels
to prevent escape of earth particles. Best results will
generally be achieved if the convex and concave curves
are part-circular, although a certain amount of
deviation from part-circular curves will normally be
permitted.
To ensure that adjacent facing panels are
positioned correctly relative to each other, the panels
are preferably provided with means for vertically
aligning the engaged side edge portions. In a preferred
embodiment the alignment means comprises a vertical hole
formed in the lateral projection of each side edge
portion, and a pin which in use is disposed in aligned
vertical holes of adjacent panels. It is thus a
relatively simple operation during construction to
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ensure that the side edge portions of adjacent panels
are corxectly aligned whilst at the same time adjustment
of the angle between the panels can be easily achieved.
Where a panel has curved convex and concave side faces
which are part-circular as discussed above, the centre
of the curves will generally be at the vertical hole of
the panel.
Various arrangements for the lateral projections
and recesses of the facing panel side edge portions are
possible. In a preferred embodiment the side edge
portion has a lateral projection extending half the
panel height and a lateral recess extending the other
half of the panel height. Whilst it is possible for a
facing panel to be formed at one side with the lateral
projection on its lower half and at the other side with
the lateral projection on its upper half, it is
particularly preferred for the lateral projections on
opposite sides of the facing panel to be provided at the
same level as each other, and the lateral recesses
similarly to be provided at the same level as each
other. The panel is then generally "T" shaped. In a
facing having a row of such facing panels, each facing
panel will be inverted relative to the laterally
adjacent panels. It will thus be appreciated that using
a plurality of like facing panels a facing for a
frictionally stabilised earth structure may be formed
with considerable scope for variation of the profile of
the facing.
In frictionally stabilised earth structures it is
normally possible to use relatively lightweight facing
panels since the earth pressures on the facing are not
particularly high. In the present context, however, it
is desirable for the lateral projections to be thicker
than the main central region of the facing panel. This
can provide increased strength and stability of the
connection with adjacent panels, whilst at the same time
saving on material by providing a relatively thin main
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central region.
The means for attaching the facing panels to at
least one frictional stabilising member may for example
comprise a lug projecting from the rear of the facing
panel. In view of the ability of the facing panels to
take up various positions relative to the overall plane
of the facing system, it is desirable for the
stabiliæing member to be attached to the lug by a single
bolt, so that the orientation of the stabilising member
is readily adjustable. Alternatively, where the angle
between the facing panel and the stabilising member is
known in advance, two or more bolts may be provided. In
the case of relatively large panels, for example 1.5m
wide by 1.5m high, a pair of lugs may be provided on
each panel e.g. one vertically above the other in the
centre of the panel. Alternatively, in a simplified
arrangement the lugs may be omitted and a stabilising
member may be attached to the vertical pin which
connects the side edge portions of adjacent panels; this
arrangement provides one stabilising member per panel
and is thus suitable for smaller panels, for example
l.Om wide by l.Om high. Even smaller panels might be
provided, for example 0.25m wide by 0.25m high.
The facing panels may typically have a thickness of
- 25 the order of 10 per cent of their height or width, so
for example the larger 1.5m by 1.5m panels may have a
thickness of 0.14m, 0.18m or 0.22m. A preferred
embodiment of the facing panel having dimensions 1.5m by
1.5m by 0.18m has a weight of 1005 kg. A preferred
embodiment of a smaller l.Om by l.Om panel has a
thickness of 0.075m and a weight of 430 kg. Where a
central region thinner than the lateral projections is
provided, the thickness of the lateral projections would
generally be at least 0.15m greater than that of the
central region.
Some preferred embodiments of the invention will
now be described by way of example and with reference to
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the accompanying drawings, in which:-
Figures 1, 2 and 3 are respectively perspective,
top plan and front elevation views of a facing panel in
accordance with the invention;
Figure 4 is a rear perspective view of the facing
panels assembled in a row;
Figure 5 is a view similar to that of Figure 4
showing an alternative form of attachment of the
stabilising members;
Figure 6 is a front perspective view showing a
structure having a facing assembled from the facing
panels; and
Figures 7, 8 and 9 are respective front elevation
views of three embodiments of facing assembled from the
facing panels.
Referring to Figures 1, 2 and 3, a facing panel 1,
made for example of reinforced concrete, has a
relatively thin central region 2 from which a pair of
lateral projections 3 extend on opposite sides. The
lateral projections each have a height equal to half the
overall height of the panel and thus give the panel a
generally "T" shaped appearance as seen in the elevation
view of Figure 3. Vertically above each lateral
projection 3 a lateral recess 4 is defined for receiving
the lateral projection of an identical facing panel to
be placed side-by-side the illustrated panel, inverted
relative thereto (see Figures 4 and 5). Each lateral
recess 4 also has a height half that of the overall
panel height.
The thickness of the lateral projections 3 is
greater than that of the central region 2 to give the
connection with an adjacent panel improved strength and
stability, particularly when the two connected panels
are positioned at an angle to each other. Such an angle
may be a right angle or any other angle less than 180~.
Each lateral projection 3 has a side face 5 formed with
a convex curve, and the upper half of the central region
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2 has opposed side faces 6 formed with a complementary
concave curve. When two panels are placed side-by-side
the convex and concave side faces 5 and 6 engage or are
in close proximity with each other, both when the panels
lie in the same plane or when they are arranged at an
angle, so as to prevent escape of particles of earth
backfill and to form a substantially continuous facing.
Each lateral projection 3 is formed with a vertical
cylindrical hole 7 which might for example be lined with
a metal or plastic sleeve (not shown). When assembling
two panels side-by-side these holes 7 are aligned and a
pin e.g. of metal is received therein to maintain the
correct relative positions of the panels. Thus a
pivotal axis is defined to enable one panel to be turned
relative to the other from a coplanar arrangement to at
least 90 either clockwise or anticlockwise.
Figure 4 shows part of a row of assembled facing
panels 1 in a coplanar arrangement. Each of these
panels is provided on its vertical centre line with a
pair of vertically spaced lugs 8, formed for example of
steel embedded in the concrete of the panel. Attached
to each lug an earth stabilising member 9 in the form of
a steel strip extends rearwardly into the earth backfill
behind the facing panels. The strips are formed with
transverse ribs on their lower and upper surfaces to
improve their frictional grip with the earth.
Figure 5 shows an alternative means of attaching
the stabilising members 9 to the facing panels 1. In
this arrangement the members 9 are attached to the
lateral projections 3 by means of a reinforcement bar
(not shown) projecting from the concrete of the panel,
for example a 16mm diameter bar. This results in the
provision of one stabilising member per panel, thus
being suitable for smaller sizes of panel. The
reinforcement bar preferably also acts as the pin
interconnecting adjacent panels, but alternatively the
pin and the bar can be provided as separate members.
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Figure 6 shows an earth structure having a facing
assembled from the panels. The facing comprises a
series of superimposed rows 10,11,12,13,14,15,16, with
exposed earth planting areas 17 being provided at the
upper level of each of rows 10 to 13, and a continuous
facing being formed by rows 14 to 16. Referring to the
lowermost row 10 a pair of laterally adjacent facing
panels la, lb are connected with their rear faces turned
towards each other and a right angle therebetween, an
angle of 270 being defined between their front faces.
An external corner 18 is thus defined in the facing. A
panel lc is arranged adjacent panel lb such that their
front faces are turned towards each other with a right
angle therebetween, an angle of 270 being defined
between their rear faces. An internal corner 19 is thus
defined in the facing.
In the superimposed row 11 a pair of facing panels
ld,le form another such internal corner 20 above and
rearwardly of the external corner 18 of row 10, so as to
define a generally horizontal exposed earth area 17.
This arrangement is repeated elsewhere in the facing to
produce earth planting areas at the upper levels of rows
10 to 13; once vegetation is established in these areas
it can substantially enhance the appearance of the
25- facing. The effect of this arrangement is also to cause
the lower part of the facing to slope to the rear.
The upper rows 14,15,16 of the facing also include
external and internal corners as described above but the
panels are laid directly on top of each other so that
the facing is continuous without planting areas.
Figures 7,8 and 9 show different ways in which rows
of facing panels 1 may be superimposed on each other
when all the panels are used in a substantially coplanar
arrangement. In Figure 7 a panel placed directly on a
panel below is inverted relative thereto. In Figure 8 a
panel placed on a panel below is in the same
orientation. The Figure 9 arrangement is similar except
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that the rows are laterally offset such that one side
face 6 of a panel central region 2 is vertically aligned
with a side face 5 of a panel lateral projection 3 in
the tier below.
