Note: Descriptions are shown in the official language in which they were submitted.
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MET~OD FOR THE LA~ERED P~ACING
OF CO~E MATERIAL AND OF THE
ADJACENT TR~SITIONAL M~TERIAL FOR DAMS
The invention relates to a method for the layered placing of
upright or sloping dam cores of material bound with bitumen
and/or plastic and/or a natural binder in a constant or
upward-tapering thickness for dams such as barrage dams.
The method can be employed, for example, for barrage dams
with or without transitional zone, consisting of finely-grained
filter material.
Various methods are currently known for placing dam cores.
One technique involves the use of formwork moulds or walls within
or inbetween which the core tttaterial is dumped. The formwork is
removed as soon as the transitional material bordering the core
has been placed up to the top edge of the core. Subsequently core
material and transitional material are compacted, either
simultaneously or at different times.
This method is time-consuming because of the discontinuous
nature of the operation, both in the horizontal and in the
vertical direction. Furthermore, no clear-cut separation is
achieved between the core material and the adjacent transitional
material.
One tnethod developed in the past, whereby both the core
material and the transitional material are placed simu]taneously
but are physically separated by walls, brought some improvement.
The drawback of this method, however, is that compaction is not
effected until the wall separating core material and transitional
material has disappeared, so that during compaction the
transitional material is forced sideways into the core material.
Although this brings about a certain degree of interpenetration
between core material and transitional material, it does have the
drawback that the ~one where core material and transitional
material interpenetrate is less compact and will exhibit cracks
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or fissures, with the result that the effective width of the
watertight core is diminished.
Systems subsequently employed, whereby the core material,
after being pre-compacted, stands free until the transitional
material is placed against the core material, have the drawback
that contamination of the core surface occurs during placing of
the transitional material; furthermore, damaging of the
free-standing core is possible.
The invention envisages an improved method for the placing
of dam cores and relates to the method stated in ~he preamble. It
is characterized in that the core material is placed from a silo
of a travelling machine; that at the same time transitional
material is placed, from one or more silos of that machine,
alongside and against the placed core material; that the dam core
is formed with the aid of a sliding formwork located on the
machine to give lateral support to the core until and while the
transitional material is placed; that the core material,
immediately af~er it has been placed and before the transitional
material is placed, is pre-compacted both vertically and
laterally; and that subsequently the core material and the
transitional material are (further) compacted.
The machine preferably travels over the already compacted
transitional material of an underlying layer.
Pre-compaction of the core material can be effected by means
of vibrating plates located on or in the formwork.
The method is preferably executed in such a way that the
transitional material is driven by means of a conveying worm in
the direction of the core material, while a second worm removes
excess material and while the top of the core is protected by a
covering plate.
It is also preferable to effect the re-compaction of the
core material and the compaction of the transitional material
simultaneously behind the ~liding formwork by means of vibrating
plates located at the rear of the machine.
If, for example, a bituminous binder is used, the core
material is preferably placed after the underlying layer of the
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core material has been heated by means of, for example,
infra-red radiators.
~y adjustment of the slidin~ formwork, the
height, breadth and fol~ of the dam core can be varied.
The invention likewise relates to a machine
for executin~ the present method, characterized in thai
it is provided with travelling elements such as cater-
pillar tyres, a silo for core material, one or more
silos for transitional material and a formwork,
especially a sliding ~ormwork, for forming the d~m
core.
Thus, in accordance with this aspect of the
invention there is provided a machine for the layered
placing o-f an upright or sloping dam core of material
bound with at least one of bitumen, plastie and
natural binder, in a constant or upward-tapering
thickness comprising a silo for core material and at
least one silo for transitional material spaced from
the core material silo, said silos being mounted Eor
spaced apart travel on travelling elements, a form-
work mounted ~or travel with said silos adapted to
provide lateral suppoxt for core material dispersed
by the core material silo, pre-eompaction means
mounted for travel with said formwork ~nd adapted
-to pre-eompaet core material dosed ~rom the core
material silo, in both the ~ertical and lateral
directions before plaeing of transitional material
from the at least one transitional material silo,
and compaction means adapted to eompact the pre-
eompacted core material and transitional material
dispersed, alongside and against the pre-compacted
core material, by said at least one transitional
material silo.
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Vibrators are preferably located on or in
the formwork for both vertical and lateral pre-com-
paction of the dam core.
At the rear, conveying worms for driving
and removing the transitional material can be loca-ted.
A covering plate is preferably provided to
protect the top of the dam core during the placing of
the transitional material.
Moreover, infra-red radiators may be pre-
sent at the front and vibrating plates at the rear.The height, breadth and form of the sliding formwork
can be varied.
By means of the described method, the
transitional material remains separated from the
core material by the sliding formwork while the
covering plate on top of the newly-laid core pre-
vents the transitional material from contaminating
the core material.
An embodiment of the invention is described
in further detail below with the aid of the drawings.
Fig. 1 represents a top view of the
machine, Fig. 2 a longitudinal section of the
machine and Fig. 3 a layout sketch of the dam core.
In the diagrams, the arrow indicates the
direction of travel of the machine. Further~.ore,
the followlng nomenclature applies
510S
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in the diagrams:
1 Infra-red burners
2 Core material silo
3 Core height control effected by means of a strike-off b~r,
which is controlled for example with the aid of a laser beam
4 Pre-compactor (vibrating plates)
Transitional material silos
~ Transitional material height control effected by means of
two strike-off bars
7 Core covering plate and lateral guide plate
8 Filling and levelling screw (controllable)
9 Vibrating plates
Travelling caterpillars
]5 Moreover, Fig. 3 shows the following zones:
A Pre-heating of already laid core
B Placing of core
C Pre-compaction of core (in lateral direction as well)
D Placing of transitional material
E Filling of transitional material against core wall
F Levelling of core material
G Compaction of core and cransitional material
One advantage of the present method is that the core
material is situated in a protective tunnel until and while the
transitional material is placed. The start of this tunnel is
joined up to the outlet of the silo 2 whence the core material is
dosed and which is provided with a vertically adjustable
strike-off bar ~ to control the height of the layer to be placed.
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In the case of bituminous core consoli~ation, the surface of
the underlying core layer is heated by infra-red radiators 1 in
order to ensure optimum adhesion between the successive layers.
Immediately downstream of the outlet of the silo, the tunnel
is provided with vibrating plates ~ (compactors), both on the
sidewalls and on the top. The advantage of lateral compaction in
conjunction with vertical compaction is that the core material is
endowed with optimum properties in terms of watertightness in
that direction in which the core is subjected to the severest
loads (horizontal water pressures) under ultimate conditions or
use. Depending upon the consistency of the core material, the
number of compactors in the longitudinal direction of the tunnel
can be increased.
In the longitudinal direction, the tunnel can consist of
several segments hinge-connected to one another. This makes it
possible to construct a hori~ontally- curved core should the
geometry of the barrage dam so require.
The transitional material is dosed from two silos 5. The
height of the placed transitional material is in the first instance
controlled by two strike-off bars 6 which are adjustable in
height. This setting can be effected independently for either
strike-off bar, thereby permitting layers of transitional
material with differing thicknesses to be placed on either side
of the core material. As the entire machine travels, wi~h the aid
of, caterpillar tyres 10, on the compacted transitional material
of the previously placed layer, it is hereby possible to tilt the
machine and thus construct a sloping core.
After the height of the transitional material has been
controlled by the bars 6, two worm screws 8 on either side of the
core ensure tha~ the transitional material is levelled by means
of a movement towards the core while a second pair of worm screws
removes any excess transitional material.
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A plate 7 on the top of the core ensures that the core material
remains free of contamination.
Subsequently, vibrating plates 9 ensure that the
transitional material is compacted and that the core material is
finally compacted.
The entire machine moves on caterpillar tyres over the
compacted transitional material of the previously placed layer.
This layer forms a sufficiently level driving surface for the
equipment in order to place a layer of core material having a
thickness lying within acceptable tolerances.
At the same time, the thickness of the layer is controlled
by the strike-off bar 3, which can receive its signals from a
laser beam.
In the longitudinal direction, positioning is effected, for
example, by sighting a paint line on the underlyin~ layer of core
material by means of a sighting device. This paint line can be
made by a device located in rhe axis of the tunnel underneath
plate 7.
To vary the width of the core, the tunnel with compaction
vibrators can be interchan~ed.
