Note: Descriptions are shown in the official language in which they were submitted.
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Self-closing sheet for encapsulating and dumping a bulk of material
FIELD OF THE INVENTION
The invention relates to a sheet to be placed in relation to a split barge for
encapsulating a bulk of material to be dumped when the bulk of material is
released, the sheet comprising a material containing portion and a material
free portion extending from at least two opposed sides of the material
containing portion. The invention further relates to a method of encapsulating
a bulk of material by means of a sheet.
BACKGROUND OF THE INVENTION
Dredging - the excavation of materials such as sediment of soil, sand, clay,
slit and/or rocks from beneath bodies of water such as rivers and oceans - is
a large global industry that makes marine construction projects possible, and
supplies a large portion of the world's sand consumption.
The industry reuses a large portion of the 9 billion cubic meter of matter it
excavates every year for construction purposes, coastal feeding or
landfilling.
However not all material is suitable. Somewhere between 22-25% of the
annual dredged volume comprises dredge spoils and fine sediments which
requires disposal, as its small grain size makes it unusable for practical
uses.
The fine sediment is therefore instead dumped offshore where it may disturb
the aquatic ecosystems, often with adverse long term effects, as the dumped
sediment can remain in the water column for up to half a year where it may
kill small organisms and in some cases cause deoxygenation.
Due to the potential hazards of oceanic dumping, the dredging industry is
being met with increasingly high dumping costs, both through rising
environmental fees and though the increased difficulty in finding suitable
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dumping sites close to excavation sites. Initiatives have therefore been taken
towards minimizing the sediment pollution caused by dumping. W010116013
disclose e.g. a hopper barge containing a geotextile insulating bag containing
a bulk of material that in some degree prevents dispersion of material when
dumped. But as the geotextile bag does not encapsulate the material some
sediment pollution may still take place.
Alternatively W09729247 discloses an example of known flexible containers
consisting of a textile fabric for receiving loose or lightly cohesive
material via
a closeable filling opening in order to form a bulk for deposition at a
selected
place, wherein the flexible container is sealed before dumping the bulk. A
disadvantage of the known operations for sealing the flexible containers is
that they are rather time-consuming.
Developers and contractors who hire dredging companies on the other hand,
are encountering higher raw material costs, as the price of raw materials
such as rocks, gravel and sand is rising due to demand and depletion of
these resources in certain regions. At the same time, dredging companies
are dumping in excess of 2 billion cubic meter of sediment annually, often
close to construction sites.
It is therefore desirable to prevent dumped sediment from spreading
throughout the water column in an easy and cost effective way and hereby
reduce the strain on the already burdened global marine environment.
Furthermore it is desirable to provide a way of increasing the utilization of
dredged material by connecting the disjoint markets; dredging disposal and
construction resources.
SUMMARY OF THE INVENTION
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Disclosed herein is a sheet being placeable in relation to a split barge and
configured for encapsulating a bulk of material to be dumped when the bulk
of material is released, the sheet comprising a material containing portion
and at least one material free portion extending from at least two opposed
sides of the material containing portion, wherein the immersed sheet
encapsulates the bulk of material and comprises an encapsulated body
encapsulated by the material containing portion and a self-closing portion
being at least a part of the material free portion both extending from an
assembly point, wherein a closing length of the self-closing portion
correspond to at least 5% of the circumventing length of the encapsulated
body, the circumventing length extending from the assembly point to the
assembly point.
The sheet may be configured for being released from the split barge before
the sheet encapsulates the bulk of material, such that the sheet when being
immersed comprises the encapsulated body encapsulated by the material
containing portion and the self-closing portion wherein the self-closing
portion
may at least be a part of the material free portion.
The circumventing length may be defined as the length of the sheet from
assembly point to assembly point when the sheet circumvents the body to be
encapsulated.
The self-closing portion may at least be a part of a closing length extending
from an assembly point towards a free end of the sheet. The free end of the
sheet may be a free edge of the material free portion.
The closing length of the self-closing portion may be between 5%, i.e. one
twentieth, and the double of the circumventing length of the encapsulated
body, more preferably may the closing length be between one fourth and one
and a half of the circumventing length of the encapsulated body.
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The sheet may hereby be configured for being released from the split barge
before the sheet encapsulates the bulk of material and/or without pre-closing
and/or pre-sealing the sheet. This may eliminate the need of handling of the
sheet after the sheet has been arranged on the split barge.
The material containing portion of the sheet may be arranged so that the
material containing portion adjoins an inside or an outside surface of the
split
barge, i.e. an outside surface of the material containing portion may be
arranged so that the material containing portion adjoins an inside surface of
the split barge or an inside surface of the material containing portion may be
arranged so that the material containing portion adjoins an outside surface of
the split barge.
The material containing portion and the sheet in its entirety may comprise a
centreline configured for being arranged along a centreline in the bottom of
the split barge. The centreline of the split barge may be parallel to the
sides,
i.e. port and starboard, of the split barge and be placed mid between the two
sides. The centreline of the material containing portion and the sheet in its
entirety may divide the material containing portion and the sheet into the two
opposite sides. The sheet may furthermore comprise another centreline
perpendicular to above defined centreline also dividing the sheet into two
opposite portions.
The material containing portion may be sized after the split barge the sheet
is
to be arranged in or on. The material containing portion may furthermore be
formed into a bag or the like fitting into the split barge the sheets is to be
arranged in or on.
In an embodiment the material free portion may comprise at least two
material free portions extending from at least two opposed sides of the
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material containing portion, whereas the opposite sides each extends from
one of the centrelines of the sheet. The two material free portions may
extend from the sides of the material containing portion arranged along the
sides, i.e. port and starboard, of the split barge. The material free portion
on
5 each of the opposite sides of the material containing portion may extend
or
may be arranged to extend approximate with the same length from the
material containing portion. The material free portion on each of the opposite
sides of the material containing portion may extend or may be arranged to
extend with different lengths from the material containing portion.
Alternatively the at least one material free portion may comprise one material
free portion extending from the entire circumference of the edge of the
material containing portion wherein at least two opposite sides of the
material
free portion approximate may extend or may be arranged to extend
approximate with the same length from the material containing portion.
The material free portions may extend along an entire side of the material
containing portion and/or along part of a side of the material containing
portion. The material free portion may be an edge portion of the material
containing portion or an added edge portion attached to the material
containing portion.
As the bulk of material is released form the split barge and the weight of the
bulk of material starts sinking the sheet towards the seabed, the sheet may
be a self-closing sheet in the sense that the material containing portion of
the
sheet is urged around the bulk of material forming an encapsulated body and
a tale, i.e. the self-closing portion comprising adjoining material free
portions
extending from at least opposite sides of the material containing portion.
This
may be achieved by the water pressure induced around the sinking sheet
without applying any other means for closing and/or sealing the sheet. The
assembly point between the encapsulated body and the self-closing portion
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may likewise be formed during sinking of the sheet encapsulating the bulk of
material.
The circumventing length of the encapsulated body may be defined as the
length from where one side of the sheet meets the opposite side of the sheet
in the assembly point.
The self-closing portion may at least comprise the one or more material free
portions or a part of the one or more material free portions. The self-closing
portion may extend from the assembly point and towards the water surface.
The advantage of enclosing the bulk of material is that the spread of the
material in the water column between the water surface and the seabed or
the bottom of a lake, river or the like is prevented when dumping the
material.
The self-closing principle is possible due to the pressure field induced
around
the sinking sheet making the material free portions of the sheet adjoin. This
as the pressure field sucks out water from within the sheet and thereby
almost instantaneously urges the material free portions of the sheet towards
each other. When the encapsulated body reaches the seabed, the sheet may
remain closed, be partially open or open fully, in which case the sediment
may be allowed to spread across the seabed.
The material to be dumped may be a substantially loose, suspendable and/or
cohesive material e.g. sediment of soil, sand, clay, slit, rocks or other
ground
material.
By split barge is meant any barge, ship or vessel configured for dumping a
bulk of material by splitting the hull or opening a bottom part such as one or
more gates or flaps arranged in the hull of the barge, ship, vessel or the
like.
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The split barge may comprise more than one compartment, wherein each
compartment is configured to hold a sheet.
A support element may be arranged on the split barge for supporting the
material free portion of the sheet when the sheet is arranged on the split
barge and during the filling of the split barge with material. The support
element may be one or more racks arranged along the edge of the split
barge. The support element may be configured for holding the material free
portion of the sheet on the outside or inside surface of the split barge.
In one or more embodiments the sheet further comprises a mechanical
and/or chemical sealing. The mechanical and/or chemical sealing may be
added to the sheet for self-sealing the sheet concurrently with self-closing
the
sheet.
The mechanical and/or chemical sealing may be added to the sheet for being
able to control when the sediment may be allowed to spread across the
seabed. Alternatively the mechanical and/or chemical sealing may be added
to the sheet if the encapsulated material is to be used as temporary building
blocks. The sheet may be suitable for any shape including both
approximately quadratic and approximately rectangular building blocks. The
building blocks may advantageously be dumped at a construction site for re-
bunding close to the dredging site.
The mechanical and/or chemical sealing may be arranged at least in the self-
closing portion of the sheet and at least on the inside surface of the sheet.
This as it is the inside surface of the self-closing portions which adjoins
during sinking of the sheet encapsulating the bulk of material.
Alternatively the mechanical and/or chemical sealing may both be attached
on the inside surface and the outside surface of the sheet. The mechanical
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and/or chemical sealing may be attached on the outside surface of the sheet
in one or both of the opposite sides of the sheet. This may allow that the
bulk
of material may be encapsulated by the sheet and sealed before releasing
the sheet encapsulating the bulk of material from the split barge.
The mechanical and/or chemical sealing may thereby be configured for being
engaged either before or after opening the split barge.
In one or more embodiments the mechanical sealing comprises a hook and
loop fastener or a mushroom fastener. The hook and loop fastener may be
known as Velcro . The mushroom fastener may e.g. be a mushroom hook
fastener known as Pressotex0. The hook and loop fastener or mushroom
fastener may at least be attached on the inside surface of the self-closing
portion of the sheet. The hook and loop fastener or mushroom fastener may
additionally be attached on the outside surface of the sheet in one or both of
the opposite sides of the sheet.
Alternatively the mechanical sealing may comprise at least one retaining barb
arranged on a strap wherein the strap may be attached to the split barge.
The strap may tightened around the self-closing portion of the sheet and
engage the barb as the encapsulated bulk of material sinks. The strap may
break or snap-off in a weak link or the like as the strap is fully
outstretched
between the split barge and the sinking encapsulated bulk of material.
In one or more embodiments the chemical sealing comprises an adhesive.
The chemical sealing may be a mushroom fastener with an adhesive known
as DuotecO. The adhesive may be applied at least to the inside surface of
the self-closing portion of the sheet. The adhesive may additionally be
applied on the outside surface of the sheet in one or both of the opposite
sides of the sheet.
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In one or more embodiments the sheet further comprises at least one
mounting element for attaching the sheet to the split barge wherein the
mounting element is configured for disengaging upon the weight of the
sinking sheet encapsulating the bulk of material.
The sheet may be mounted to the split barge by means of a mounting and
release system for mounting and releasing the sheet to/from the split barge.
The mounting and release system may comprise a corresponding mounting
element, wherein the mounting element is disengaged from the
corresponding mounting element upon the weight of the sinking sheet
encapsulating the bulk of material.
The mounting element may be any element on or in the sheet suitable for
being used for unfolding the sheet and arranging the sheet on the split barge
and/or to attach the sheet directly or indirectly to the split barge. The
mounting element may be used for attaching the edge of the sheet to an
upper edge or the side of the split barge.
The sheet may be released from the split barge after the split barge opens
and when the sheet is fully outstretch from a centre line or a centre point of
the sheet to the edge of the sheet as the weight of the material on the sheet
pushing the sheet into the water. This may be an advantages as the
mounting of the edge of the sheet may facilitate that the sheet is fully
outstretch when it enters the water so that the formation of an assembly point
and self-closing portion may become more efficient. Furthermore this may
together with the self-closing concept render the dumping of encapsulated
material quick and easy without the need for any manpower for pre-closing
and/or pre-sealing the sheet.
In one or more embodiments the mounting element comprises a strap and a
snap-off element. The corresponding mounting element may be a hook
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attached directly or indirectly to the split barge. The hook may be a
conventional open and/or closed load bearing hook.
In one or more embodiments the snap-off element comprises a weak link
5 along the strap configured for being broken. The weak link may be broken
by
the weight of the sinking sheet encapsulating the bulk of material.
In one or more embodiments the snap-off element comprises a snap-off
button. The snap-off button may be placed along the length of the strap so
10 that the strap is split into two portions when the snap-off button is
disengaged. Or the snap-off button may be placed in one of the ends of the
strap.
It may be obvious for a skilled person that the mechanical and/or chemical
sealing additionally may be used as a mounting element and that the
mounting element additionally may be used as a mechanical and/or chemical
sealing.
In one or more embodiments the mounting element and/or the mechanical
sealing comprises a magnet.
One or more magnetic tapes and/or a plurality of magnets may be attached
on or in the self-closing portion of the sheet. The magnets may be suitable
for
releasably attaching the sheet to the split barge as the split barge may be
made of steel, whereas the magnets preferably is arranged at least in the
edge of the sheet. The magnets may alternatively or concurrently be suitable
for obtaining a self-sealing of the self-closing portion of the sheet whereas
the magnets either may be arranged in the edge portion and/or so that they
substantially covers the self-closing portion of sheet. The magnets may be
suitable for sealing the sheet both before and after opening the split barge.
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Alternatively the mounting element may comprise a strap without a snap-off
element and a rope may comprise a snap-hook with a release mechanism,
whereas the snap-hook may be fixed in on end to the rope and releasably
attached to the strap in the other end. The release mechanism may be
tricked by a pull with a certain weight corresponding to the weight of the
sinking sheet encapsulating the bulk of material.
In one or more embodiments the sheet is made of a degradable material.
The choice of type of degradable material may be based on when the bulk of
material may be allowed to spread along the seabed.
The degradable material may be a biodegradable material. The
biodegradable material may be a fiber based geotextile. The fiber based
geotextile may be made from coconut fibers or jute. A geotextile made from
coconut fibers or jute may be ideal for a completely degradable sheet. The
geotextile may be surface treated in a water soluble biopolymer, ensuring
that the geotextile degrades after a few years.
In one or more embodiments the sheet is made of a permanent material. The
permanent material may be used if the encapsulated material is to be used
as building blocks. The permanent material may be polypropylene and/or
polyacetate.
The sheet may be made from the permanent material when the encapsulated
bulk of material is used as building blocks e.g. for the use as the core or
base
of a dam, a quay, a bank reinforcement, a jetty or a breakwater, for filling
holes or trenches in the bed of a waterway or the like.
In one or more embodiments the self-closing portion of the sheet is made
from a different material than the remaining sheet. The material used for the
self-closing portion my have a lower strength than the material used for the
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remaining sheet, whereas the remaining sheet includes at least the material
containing portion of the sheet.
In one or more embodiments the sheet may comprise an outer sheet
configured for being attached to the split barge such that the sheet, as
described above, constitute an inner sheet configured for being in contact
with the bulk of material.
The outer sheet may be configured for being in direct contact with the split
barge on one side and the inner sheet on the other side and the inner sheet
may be configured for being in direct contact with the outer sheet on one side
and the bulge of material on the other side. I.e. the inner and outer sheet
may
be arranged along an inside surface of the split barge. The surface of the
inner sheet being configured for being in contact with the outer sheet may
comprise a low friction surface, i.e. be slibbery.
The outer sheet may be attached to the split barge along an edge or part of
an edge of the outer sheet by means of one or more wires attached to the
split barge in one end and to the outer sheet in the other end. The wire(s)
may be hooked to the split barge and/or to the outer sheet.
When using a sheet comprising the inner sheet and the outer sheet the bulge
of material may be placed on/upon both the inner and the outer sheet in
direct contact with the inner sheet. As the split barge is opened, the bulge
of
material starts to settle into the water beneath the split barge. At some
point,
determined by the length of the one or more wire(s), the wire(s) is tightened,
causing the inner sheet to slide off the outer sheet. The inner sheet
continues
sinking towards the sea bed while the outer sheet will hang in the wire(s) and
may be pulled back up into the split barge.
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The material containing portion of the inner sheet may be configured for
being folded, for example zig-zag folded, when being placed in the split
barge. Folding parts of the inner sheet arranged along the inside surface of
the split barge, may facilitate a degree of extendibility of the inner sheet.
The
provided excess material of the inner sheet may unfold during immersion of
the bulge of material. The unfolded excess material of the inner sheet may
provide an extendibility of the self closing portion of the inner sheet.
The outer sheet may be configured to withstand the peak forces in/on the
sheet occurring when the bulge of material squeezes through the split barge
when being opened. The outer sheet may be configured to protect the inner
sheet from being teared up by sharp or rough surfaces and/or edges or other
irregularities in/on the split barge. The outer sheet may be a TenCate sheet
or the like. The inner sheet may be configured to withstand the forces
imposed on the sheet during descent toward the sea bed. The inner sheet
may thereby be made of a material having a lower strength than when only
using one sheet.
The cost of manufacturing the sheet is related to the requirements on the
material strength. The advantage of using a sheet comprising the inner sheet
and the outer sheet is that the inner sheet, which may be configured for
single use, may require a relative low material strength and thereby have a
relative low manufacturing cost. The outer sheet requiring a higher material
strength and thereby a higher manufacturing cost may be reusable.
Further disclosed herein is a method of encapsulating a bulk of material by
means of a sheet as described above, the method comprising; arranging the
sheet in or under the split barge, filling the sheet or the split barge with
the
bulk of material, opening the split barge so that the weight of the bulk of
material starts sinking the sheet towards the seabed, encapsulating the bulk
of material followed by leading the sheet into an assembly point by means of
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the water pressure induced around the sinking sheet, and engaging the self-
closing of the self-closing portion.
The step of opening the split barge may hereby be done before the sheet
may be closed around the bulk of material and optionally sealed.
If the sheet is mounted to the split barge with the mounting element, the step
of disengaging the mounting element may be done between the steps of
opening the split barge and encapsulating the bulk of material.
In one or more embodiments, wherein the sheet comprises the mechanical
and/or chemical sealing, the method further comprises engaging the
mechanical and/or chemical sealing concurrently with engaging the self-
closing of the self-closing portion.
In one or more embodiments, wherein the sheet comprises the outer sheet
such that the sheet, as described above, constitute an inner sheet, the
method further comprises retrieving the outer sheet to the split barge.
The outer sheet may be attached to the split barge along an edge or part of
an edge of the outer sheet by means of one or more wires attached to the
split barge in one end and to the outer sheet in the other end. The wire(s)
may be hooked to the split barge and/or to the outer sheet.
The outer sheet may be retrieved by pulling the outer sheet back into the
split
barge. The outer sheet may be retrieved to or pulled back into the split barge
before closing the split barge.
Further disclosed herein is a method of encapsulating a bulk of material by
means of a sheet as described above, the method comprising; arranging the
sheet in the split barge, filling the sheet with the bulk of material,
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encapsulating the bulk of material, engaging the mechanical and/or chemical
sealing, and opening the split barge releasing the encapsulated bulk of
material which sinks towards the seabed.
5 If the sheet is mounted to the split barge with the mounting element, the
step
of disengaging the mounting element may be done between the steps of
filling the sheet and encapsulating the bulk of material.
This method may be particular useful when dumping on very low depths
10 where the self-closing effect may not have the right conditions for
working
properly.
In one or more embodiments, wherein the sheet comprises the outer sheet
such that the sheet, as described above, constitute an inner sheet, the
15 method further comprises retrieving the outer sheet to the split barge.
The outer sheet may be attached to the split barge along an edge or part of
an edge of the outer sheet by means of one or more wires attached to the
split barge in one end and to the outer sheet in the other end. The wire(s)
may be hooked to the split barge and/or to the outer sheet.
The outer sheet may be retrieved by pulling the outer sheet back into the
split
barge. The outer sheet may be retrieved to or pulled back into the split barge
before closing the split barge.
BRIEF DESCRIPTION OF THE DRAWINGS
Different embodiments of the invention will now be described, by way of
examples only, with reference to the accompanying drawings, as follows;
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Fig. 1 schematically shows a cross-sectional view of a sheet according to the
invention with a self-closing portion and working by the self-closing concept;
Fig. 2 schematically shows a cross-sectional view of a sheet according to the
invention arranged on a split barge;
Figs. 3A and 3B schematically show the disengagement of the sheet from the
split barge according to the invention, and
Fig. 4 schematically shows the use of different embodiments for sealing the
sheet according to the invention.
Fig. 5 schematically shows a cross-sectional view of a sheet according to the
invention comprising an inner sheet and an outer sheet.
DESCRIPTION OF PREFERED EMBODIMENTS
Fig. 1 schematically shows a sheet 1 according to the invention with a self-
closing portion 22 and working by a self-closing concept, whereas the self-
closing concept works as following:
First the sheet 1 is arranged on or in a split barge 100 and a material
containing portion 4 of sheet is filled with a bulk of material 101. A
centreline
of the sheet may approximately follow a centreline 106 of the split barge. A
material free portion 3 of the sheet is hold along the edge of the split barge
by a support element (not shown). In the presently illustrated embodiment
and as shown in Fig. 2 the material containing portion of the sheet is
arranged along an inside surface 103 of the split barge and the material free
portion is hold by a support element 102 along an outside surface 104 of the
split barge. Alternatively the sheet may be arranged along an outside surface
of the split barge. The material free portion 3 may be zig-zag folded.
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Then the split barge 100 is opened and the weight of the bulk of material 101
pushes the sheet 1 into the water. As the sheet and bulk of material sinks
towards the seabed the water pressure around the sheet encapsulates the
bulk of material forms an encapsulated body 20 and collects the material free
portion 3 into a tale following the sinking encapsulated bulk of material. In
the
presently illustrated embodiment the tale starts at an assembly point 21 and
extends toward the water surface, whereas the tale constitutes a self-closing
portion 22 extending from the assembly point an away from the encapsulated
body.
As the encapsulated body 20 may shift into different forms during immersion
the assembly point may shift and a closing length of the self-closing portion
may vary during immersion. Furthermore may the closing length, i.e. the
length of the self-closing portion from the assembly point to the edge of at
least one of the opposite sides of the sheet, and hereby the formation of the
assembly point of at least two opposite sides of the sheet likewise depend on
the density of the bulk of material as well as the volume of the bulk of
material, as the split barge may not be properly filled or even only half
filled
when the split barge is opened and the bulk of material is released entailing
a
longer closing length.
Figs. 3A and 3B schematically show the disengagement of the sheet 1 from
the split barge 100 according to the invention. In the presently illustrated
embodiment the mounting element 5 comprises a magnet arranged on the
edge 2 of the material free portion 3 of the sheet.
After the split barge 100 has been opened and the sheet 1 and the bulk of
material (not shown) sinks towards the seabed the sheet may as in the
presently illustrated embodiment be dragged along the inside surface of the
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split barge, see Fig. 1, disengaging the mounting element 5 when the sheet
is fully outstretched.
The mounting element 5 may engage directly with the split barge 100 or with
a corresponding mounting element 105 arranged on the split barge or on the
support element 102.
Fig. 4 schematically shows the use of different embodiments for sealing the
sheet 1 according to the invention.
The sheet may comprise a mechanical sealing 10 or a chemical sealing in at
least the self-closing portion 22 of the sheet. In the presently illustrated
embodiment it is shown how the sheet can comprise a hook and loop
fastener 11 and/or a mushroom fastener 12 on the inside surface 103 of the
sheet.
Fig. 5 schematically shows the sheet 1 according to the invention comprising
an outer sheet la wherein the sheet 1 constitutes an inner sheet lb. In the
presently illustrated embodiment the outer sheet and the material containing
portion 4 of the inner sheet are arranged along the inside surface 103 of the
split barge 100 and the material free portion 3 of the inner sheet is hold by
a
support element (not shown) along the outside surface 104 of the split barge.
The material free portion 3 may be zig-zag folded. Alternatively the outer
sheet and/or the inner sheet may be arranged along the outside surface of
the split barge. One or more wires 30 (illustrated by the stippled line) are
attached to the split barge in one end and the outer sheet in the other end.
The self-closing concept works as described above with the addition of that
when the split barge 100 is opened and the weight of the bulk of material 101
pushes the outer sheet la and the inner sheet lb into the water, the wire(s)
30 is tightened, causing the inner sheet to slide off the outer sheet. The
inner
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sheet continues sinking towards the sea bed while the outer sheet will be
hanging in the wire(s) until outer sheet is pulled back up onto the split
barge.
As the inner sheet lb and bulk of material 101 sinks towards the seabed the
water pressure around the sheet encapsulates the bulk of material forming
an encapsulated body (not shown) and collects the material free portion 3
into a tale following the sinking encapsulated bulk of material.
