Static structures (e.g. – buildings) – Installed screed or unit with specified feature retaining... – Composite – including pierceable nonmetal component
Reexamination Certificate
2000-03-08
2001-12-25
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Installed screed or unit with specified feature retaining...
Composite, including pierceable nonmetal component
C052S127200, C052S576000, C052S098000, C052S099000, C249S207000
Reexamination Certificate
active
06332297
ABSTRACT:
The present invention relates to a device for facilitating the removal of formwork for the end joint of a diaphragm wall panel.
BACKGROUND OF THE INVENTION
When it is desired to make a diaphragm wall, i.e. a wall made of concrete in a trench dug in the ground, this operation is performed in successive segments, each corresponding to a panel of the diaphragm wall, and the set of panels constitutes the wall.
To provide mechanical continuity between wall panels in a zone where two panels meet, the end of each panel is given a special “joint” shape enabling the end of each panel to be received in the end of the preceding panel. This shape corresponding to the joints is defined at the end of the trench that is being dug by inserting formwork of a shape that forms the joint of the panel that is being made.
With reference initially to
FIGS. 1A and 1B
, there follows a description of the prior art technique for making the various panels of a diaphragm wall. Initially, a first portion of trench
10
is dug corresponding to a first panel, and end joint formwork
12
is placed at the end
10
a
of the portion of trench. In conventional manner, the formwork
12
comprises a soleplate
14
and a box
16
defining the shape of the joint, and preferably also comprises a structure
18
enabling a connection element
20
to be held and protected between sealing elements that can be provided in the diaphragm wall.
As shown in
FIG. 1A
, the concrete constituting the panel
22
passes round the ends of the soleplate
14
of the formwork
12
in side zones referenced
24
. Some of this concrete can even end up against the outside face
14
a
of the soleplate
14
, as shown at
26
.
In the following step, as shown in
FIG. 1B
, a second portion of trench
28
is dug to constitute the following panel of the diaphragm wall. During this digging, the bucket of the mechanical digger can be used to scrape the outside wall
14
a
of the soleplate
14
so as to remove the corresponding portion of concrete. However, experience shows that there always remains some of the concrete that has passed round, as referenced
24
.
Prior to filling the second portion of trench
28
, it is of course necessary to extract the formwork
12
. This operation is difficult because of the adhesion between the concrete and both with the box
18
and with the inside face
14
b
of the soleplate
14
. In addition, this operation is made even more difficult because of the presence of concrete that has passed round in the zones
24
.
To solve that problem, proposals have already been made in French patent 2 613 395 to coat the face of the formwork that faces into the concrete in a thin material that can be abandoned in the trench so as to avoid adhesion between the concrete and the formwork, and to extract the formwork substantially vertically.
Proposals have also been made to solve the same problem in French patent 2 647 828 by applying a shock to the joint on its side remote from the concrete by means of a tool that is guided by the joint itself.
Another known technique for removing the formwork
12
consists in using removal “hooks” which consist, as explained in greater detail below, essentially in two hook-shaped pieces which are engaged on the edges of the soleplate of the formwork and whose active portions are engaged against the inside face of the soleplate at its edges.
FIG. 1C
shows the general shape of such removal hooks
30
and
32
when in place.
FIG. 1D
shows a removal hook
30
. It comprises one end
31
for connection to a machine, an arm
33
for passing round the side edge of the soleplate
14
, and a flange
30
a
for insertion between the inside face
14
b
of the soleplate and the concrete in order to unstick the formwork from the concrete.
Because of the presence of concrete in the zones
24
where it passes round the edges of the soleplate, it is very difficult to engage the removal hooks
30
and
32
. The hooks need to clear themselves a passage round the edge zones
24
over a width of 2 cm to 3 cm (referenced e) corresponding to the width of the removal hooks, and to do so over a length that may exceed 5 cm (referenced e′) corresponding to how far the concrete has gone past in the zones
24
. This operation puts very large stresses on the removal hooks and can lead to them breaking or at least to wearing out very prematurely. In addition, jamming phenomena make this operation difficult and thus lengthy, thereby giving rise to non-negligible cost in the construction of the diaphragm wall.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a device for facilitating the removal of formwork for the end joint of a diaphragm wall panel, which device makes it possible to use removal hooks under conditions that are greatly improved thus making it possible to limit the wear on the removal hooks and to increase the speed with which the removal operation can be performed.
To achieve this object, the invention provides a device for facilitating removal of formwork for the end joint of a panel of a diaphragm wall, said formwork comprising a soleplate having an outside face, an inside face carrying a box, and two side edges, said box leaving two empty side zones on the inside face of the soleplate in the vicinity of said edges, the device comprising:
two substantially rectangular plates of substantially the same dimensions;
spacer means secured to a first longitudinal edge of each of said plates to hold them substantially parallel to each other at a spacing h that is substantially equal to the thickness of the soleplate of the formwork;
filler means for filling the volume defined by said plates, by the spacer means, and by a plane orthogonal to said plates at a distance d from the other longitudinal edges of the plates, whereby the space between said plates that does not include filler means is suitable for receiving a side portion of the soleplate, said filler means being made of a low strength material; and
temporary fixing means for fixing said plates on said soleplate.
It will be understood that by means of this disposition, the removal hooks can be engaged vertically on either side of the soleplate in register with those portions of the devices for facilitating removal that are constituted at least in part by the filler means whose mechanical strength is relatively low. Thus, the removal hooks can be pushed into the zones that have no concrete going round the edges as constituted at least in part by the relatively weak filler material.
In addition, the very presence of devices for facilitating removal limits the size of the zones occupied by the concrete that has gone round the edges.
In a first embodiment said plates and said spacer means are constituted by a metal sheet shaped to comprise two flanges interconnected by a web, and said filler means are constituted by a piece in the form of a rectangular parallelepiped disposed between the flanges of the metal sheet and against the web, said filler means being made of a plastics material that is unsuitable for being impregnated by concrete.
In a second embodiment said plates are made of wood, said spacer means are constituted by a wooden batten fixed between said plates along the first longitudinal edges thereof, and the filler means are constituted by a piece in the form of a rectangular parallelepiped disposed between said plates and against said batten, said piece being made of a plastics material that is unsuitable for being impregnated by concrete.
In a third embodiment said plates are made of wood, said spacer means are constituted by strips of wooden batten fixed between said plates along the first longitudinal edges thereof, said strips of batten leaving empty gaps between one another in the longitudinal direction of the edges of said plates, and the filler means are constituted by pieces substantially in the form of rectangular parallelepipeds of a plastics material that is unsuitable for being impregnated by concrete, said pieces being disposed in the gaps between the strips of batten.
In a preferred embodiment, the fil
Compagnie Du Sol
Dennison, Scheiner Schultz & Wakeman
Friedman Carl D.
Slack N.
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