[0001] The present invention relates to a removable anchor block which is suitable for insertion
into the ground and is used for absorbing tensile forces which occur, for example,
during the stabilization of temporary structures such as sheet pile walls.
[0002] The invention also relates to a method for inserting such an anchor block into the
ground as well as a method for removing such an anchor block from the ground.
[0003] Anchor blocks are generally known and are used to stabilize certain structures such
as sheet pile walls, in which process in particular lateral forces are absorbed, or
partially absorbed, by the anchor block. The anchor blocks currently in general use
are difficult or impossible to remove after insertion into the ground, which is undesirable.
[0004] EP 444 667 discloses an anchor block which can be removed from the ground, comprising a plate-shaped
element with two fixing points and two pulling cables. The first pulling cable is
fixed in the centre of the plate-shaped element and serves to absorb the tensile force
exerted by the object to be anchored. The other, second pulling cable is fixed in
a corner of the plate-shaped element and serves to make removal of the anchor block
possible.
[0005] A disadvantage of the anchor block known from
EP 444 667 is that it is difficult to insert in a desired position.
[0006] The object of the invention is to provide a removable anchor block which is easy
to insert into the ground in the desired position.
[0007] The object is achieved with an anchor block according to claim 1.
[0008] The phrase distributed around the circumference should be understood to mean that
at least two of the two or more fixing points are provided on either side of a centre
point or centre line of the surface of the plate-shaped element. This means that if
one of the two pulling cables is pulled, the plate-shaped element will tilt in a first
direction while, if one or more of the other pulling cables is pulled, the plate-shaped
element will tilt in an opposite direction.
[0009] The advantage of such an anchor block is that during pulling of the pulling cables
fixed on the plate-shaped element the position of the plate-shaped element is easy
to determine because the length of the cables is known. Since the position of the
plate-shaped element is known and the position of the plate-shaped element can be
controlled by the two cables, it is easy to bring the plate-shaped element into the
correct position.
[0010] The two or more fixing points are preferably provided near an edge of the plate-shaped
element. Placing the fixing points near the edge means that it is easy to take the
plate-shaped element into its desired position. A fixing point placed at the edge
makes it easier here to remove the plate-shaped element from the ground. Since in
the case of two fixing points they are both placed at the edge, it is furthermore
not important which of the two cables has to be pulled in order to remove the plate-shaped
element from the ground.
[0011] The phrase near the edge should generally be understood to mean away from the centre
point of the surface of the plate-shaped element. The closer the fixing points are
to the edge, however, the better the abovementioned effect will be achieved.
[0012] The edge of the plate-shaped element is advantageously at least partially bevelled
or sharpened in order to make it easier to insert the plate-shaped element into the
ground and/or pull it out of the ground.
[0013] The anchor block preferably comprises a connecting part which is suitable for connecting
to an elongated pushing element, in particular a pushing tube, by means of which the
plate-shaped element can be pushed into the ground in a direction substantially parallel
to the surface of the plate-shaped element. With such a connecting part it is ensured
that during the insertion of the plate-shaped element into the ground said plate-shaped
element remains in the correct position.
[0014] The anchor block preferably comprises two or more pulling cables, each of which is
permanently or detachably connected to one of the two or more fixing points, it being
furthermore preferable for the two or more pulling cables to be of the same length.
[0015] The desired position of the anchor block according to the invention after it has
been inserted into the ground is such that the surface of the plate-shaped element
is substantially perpendicular relative to the direction in which it has been inserted
into the ground. Said desired position is easy to achieve, for example by using pulling
cables of the same length. By making the pulling cables of the same length converge
in one pulling point, for example by connecting them to a single pulling hook, it
is easy, by pulling these cables until all cables are taut, to determine that the
plate-shaped element is in the desired position.
[0016] However, since the length of the cables is known, the position and orientation of
the plate-shaped element can be determined by means of each set of two pulling cables
during pulling of these pulling cables.
[0017] In one embodiment the pulling cables are pivotly fixed in the fixing points, the
pivoting being possible only about an axis lying in the plane of the plate-shaped
element. During the insertion of the plate-shaped element into the ground, the axis
preferably also lies perpendicular to the direction of insertion.
[0018] In one embodiment the pulling cables are in the form of chains. Chains have been
found very suitable as pulling cables for the plate-shaped anchor, since with a small
diameter they are relatively strong.
[0019] The invention furthermore provides a method, described in claim 16, for inserting
an anchor block into the ground according to one or more of claims 1 - 15, which method
is characterized by the following steps:
- connecting the plate-shaped element to an elongated pushing element, in particular
a pushing tube,
- pushing the plate-shaped element into the ground,
- disconnecting the anchor block and removing the pushing element from the ground,
- bringing the anchor block into a desired position by pulling the two or more pulling
cables connected to the plate-shaped element in such a way that the plate-shaped element
tilts into the desired position, and
- connecting to the pulling cables the object which is to be anchored by the anchor
block.
[0020] The invention furthermore provides a method for removing an anchor block according
to one or more of claims 1 - 15, which method is described in claim 20 and is characterized
by pulling one of the two or more pulling cables in such a way that the plate-shaped
element tilts and can be pulled out of the ground in a direction substantially parallel
to the surface of the plate-shaped element.
[0021] The invention will be explained in greater detail below with reference to a number
of exemplary embodiments, in which reference is made to the drawing. In the drawing:
Figure 1 shows a top view of a first embodiment of an anchor block according to the
invention,
Figure 2 shows a top view of a second embodiment of an anchor block according to the
invention,
Figures 3a - 3c show a number of the steps of a method according to the invention,
Figures 4a and 4b show a top view and an elevational view respectively of a cross
section of a third embodiment of an anchor block according to the invention, and
Figure 5 shows a top view of a possible application of an anchor block according to
the invention.
[0022] Figure 1 shows a first embodiment of an anchor block indicated in its entirety by
reference numeral 1. The anchor block 1 comprises a plate-shaped element 2, which
is provided with two fixing points 3 for fixing a pulling cable on each of the fixing
points 3, detachably or otherwise. The fixing points can be in the form of, for example,
eyes welded on the plate-shaped element 2, through which eyes the cables to be fixed
are inserted, or they can be in the form of holes made in the plate-shaped element
2, in which holes the fixing cables are fixed.
[0023] The plate-shaped element 2 can be made of, for example, a suitable type of metal,
for example steel.
[0024] The fixing points 3 are substantially distributed around the circumference of the
plate-shaped element, i.e. in this case the two fixing points are fixed on either
side of the centre point A of the surface of the plate-shaped element 2.
[0025] The fixing points 3 are provided near the edge 2a of the plate-shaped element, in
order to make it easily possible to bring the plate-shaped element 2 into the desired
position when it is being inserted into the ground.
[0026] The anchor block 1 furthermore comprises a connecting part 4, which is suitable for
connecting to an elongated pushing element 5, only the end of which is shown in Figure
1, and by means of which the plate-shaped element 2 can be pushed into the ground
in a direction substantially parallel to the surface of the plate-shaped element 2.
[0027] The connecting part 4 is in the form of a part projecting from the plate-shaped element
2, which part is complementary to an end of the elongated pushing element 5. The end
of the pushing element 5 in fact comprises a hollow part which can be placed around
the projecting part of the plate-shaped element 2, so that the pushing element keeps
the orientation of the plate-shaped element 2 the same relative to the pushing element
5 during the insertion of the plate-shaped element 2 into the ground.
[0028] The edge 2a of the plate-shaped element 2 is at least partially bevelled or sharpened
in order to make it easier to insert the plate-shaped element 2 into and/or pull it
out of the ground. In particular, the plate-shaped element is bevelled or sharpened
on the side facing away from the connecting part. This will make it easier to insert
the plate-shaped element 2 into the ground during pushing of the plate-shaped element
2 by means of the pushing element 5.
[0029] The dimensions of the plate-shaped element 2 are, for example, 0.3 by 0.5 metre.
In general, the dimensions are preferably in the region between 0.2 and 2.0 metres,
more preferably in the region of 0.4 to 1.0 metre. A plate-shaped element with these
dimensions is, on the one hand, easy to manoeuvre in a large number of types of ground,
while at the same time it has sufficient surface area to be able to absorb a great
tensile force.
[0030] Figure 2 shows a second embodiment of an anchor block 1. The same parts are indicated
by the same reference numerals in Figure 2.
[0031] In this second embodiment the anchor block 1 comprises a plate-shaped element 2 which
is in circular form. The plate-shaped element 2 comprises three fixing points 3 which
are distributed around the circumference of the plate-shaped element 2 and near the
edge 2a of the plate-shaped element 2. Distributed around the circumference means
here that the fixing points are provided at 0, 120 and 240 degrees of the circular
plate-shaped element relative to the centre point A of the circular plate-shaped element
2.
[0032] A connecting part 4 comprising a drilled hole 6 with internal screw thread is provided
on the plate-shaped element 2. A projecting part 5a with an external screw thread
is provided on the pushing tube 5, which external screw thread is complementary to
the internal screw thread in the drilled hole 6. The pushing tube 5 and the plate-shaped
element 2 can be connected to each other by means of the screw threads, in which case
it is ensured that the orientation of the plate-shaped element 2 relative to the pushing
element 5 is maintained during the insertion of the plate-shaped element 2 into the
ground.
[0033] In this embodiment of the plate-shaped element 2 also, the three fixing points 3
are provided near the edge of the plate-shaped element, in order to make manoeuvring
under the ground easier.
[0034] In this embodiment also, the edge 2a of the plate-shaped element, in particular on
the side of the plate-shaped element 2 facing away from the connecting part 4, can
be bevelled or sharpened in another way in order to make it easier to insert the plate-shaped
element 2 into the ground.
[0035] The diameter of the plate-shaped element 2 is approximately 0.6 metre. In general,
the diameter of a plate-shaped element 2 in circular form lies between 0.2 and 2.0
metres, more preferably between 0.4 and 1.0 metre. A plate-shaped element with these
dimensions is, on the one hand, easy to manoeuvre in a large number of types of ground,
while at the same time it has sufficient surface area to be able to absorb a great
tensile force.
[0036] The method for inserting an anchor block into the desired position into the ground
and removing it again after use will now be explained with reference to Figures 3a
- 3c.
[0037] Figures 3a - 3c show diagrammatically an elevational view of a cross section of a
foundation pit 10. For excavation of the foundation pit a sheet pile wall 11 is provided
on the side of said foundation pit. Through the presence of the ground 12 on the side
of the sheet pile wall 11 away from the foundation pit 10, pressure is exerted upon
the sheet pile wall 11, with the result that the latter is pushed in the direction
of the foundation pit 10. In order to prevent movement of the sheet pile wall in this
direction, use is made of one or more anchor blocks, by means of which the sheet pile
wall 11 is anchored to the ground 12.
[0038] The insertion of the anchor block 1 into the ground is shown in Figure 3a. The anchor
block 1 is substantially designed as described in Figure 2. The plate-shaped element
2 is connected by means of the connecting part 4 to an elongated pushing element,
in particular a pushing tube 5. By way of the pushing tube 5, the plate-shaped element
2 is inserted into the ground in a direction substantially parallel to the surface
of the plate-shaped element. The pushing tube can be pushed in a manner known per
se, for example by means of a pile-driving device or a suitable vibrating device (not
shown).
[0039] Three pulling cables 7 are connected to the three fixing points 3 of the plate-shaped
element 2 of the anchor block 1. During the insertion of the anchor block 1 into the
ground 12 by means of the pushing tube 5, the pulling cables 7 do not yet have any
specific function.
[0040] After the plate-shaped element 2 has been inserted to the desired depth, for example
in a sand layer which gives sufficient strength for anchoring of the sheet pile wall
11, the pushing tube 5 is disconnected from the plate-shaped element 2 and removed
from the ground 12.
[0041] After the pushing tube 5 has been removed from the ground 12, the plate-shaped element
2 can be tilted to the desired position in the ground 12. In general, the desired
position is the position in which the surface of the plate-shaped element 2 is substantially
perpendicular to the direction in which the tensile forces of the object to be anchored,
in this case the sheet pile wall 11, are exerted.
[0042] Pulling the three pulling cables 7 enables the plate-shaped element 2 to be tilted,
so that it moves to the desired position. Since the length of the pulling cables 7
is known, it is possible while taking the plate-shaped element 2 to the desired position
to determine the position of the plate-shaped element 2 on the basis of the lengths
of the pulling cables 7 which are situated in the ground 12. It is therefore possible
to control the plate-shaped element 2 in such a way that it moves to the desired position.
[0043] All three of the three pulling cables 7 are advantageously of the same length, and
the pulling cables 7 are preferably pulled from one pulling point, as shown in Figure
3b. One pulling point here means, for example, the hook of a crane. The pulling cables
7 can advantageously be provided with a loop-shaped end, which can be placed in a
simple manner on the hook of the crane.
[0044] When pulling cables 7 of equal length are used, it is clear that when all three of
the pulling cables 7 are taut, the plate-shaped element 2 is in the desired position.
If one or two of the pulling cables 7 is/are slack, the side of the plate-shaped element
2 that is connected by way of the fixing points 3 to said pulling cable 7 or pulling
cables 7 is too close to the sheet pile wall 11 compared with the other side of the
plate-shaped element 2.
[0045] Figure 3b shows how the three pulling cables 7 are pulled simultaneously by a crane
hook 13, so that the plate-shaped element 2 goes into the desired position. By means
of a plate 14, the three pulling cables 7 are connected to the sheet pile wall 11
to be anchored. After direct or indirect connection of the pulling cables 7 to the
sheet pile wall to be anchored, the anchor block 1 gives resistance to the movement
of the sheet pile wall 11 in the direction of the foundation pit 10.
[0046] The anchor block shown, with a diameter of approximately 0.6 metre in suitable ground
can absorb a force of 40 - 70 tonnes, which is ample for the purpose described.
[0047] If the foundation pit 10 is no longer needed and the sheet pile wall 11 can therefore
be removed, the anchor block 1 is no longer needed. It is generally desirable to remove
the anchor block 1 from the ground after use, in particular if the anchor block 1
has been inserted into the ground of a person who is not the owner of the ground where
the building has been carried out.
[0048] Figure 3c shows how the anchor block 1 can be removed easily from the ground 12 after
use. After the pulling cables have been disconnected from the object to be anchored,
in this case the sheet pile wall 11, one of the pulling cables 7 can be pulled, for
example by connecting one of the pulling cables 7 to the hook 13 of a crane.
[0049] Since said pulling cable 7 is fixed to a fixing point 3 which is not in the centre
of the surface of the plate-shaped element 2, the plate-shaped element will leave
the desired position and tilt to a position in which the surface of the plate-shaped
element 2 is lying substantially parallel to the direction in which the pulling cable
7 being pulled is running. As a result, the resistance exerted by the ground upon
the plate-shaped element 2 will decrease, and it will be possible to pull the plate-shaped
element out of the ground with a relatively low force.
[0050] The remaining pulling cables 7 can hang loose during the pulling and can be pulled
slowly with the other cable or can be pulled out of the ground after the plate-shaped
element 2 has been removed from the ground.
[0051] The pulling force required for pulling an anchor block of the type shown in Figures
3a - 3c with a diameter of approximately 0.6 metre out of the ground can lie in the
region of 5 - 10 tonnes.
[0052] After the removal of the anchor block, it can be reused for anchoring a particular
object. Depending on the ground where the anchor block 1 is being used and the force
which the anchor block is intended to absorb, certain dimensions of the anchor block
can be selected. The user advantageously has anchors with different dimensions at
his disposal.
[0053] Any cables which have sufficient strength for absorbing the forces occurring can
be used as the pulling cables 7. Steel cables or chains are preferably used.
[0054] Figures 4a and 4b show a removable anchor block according to the invention which
is particularly suitable for chains, indicated in its entirety by the reference numeral
10. The anchor block 10 comprises a plate-shaped element 11, which is substantially
rectangular. The plate-shaped element 11 comprises two fixing points which are formed
by two pins 12, which are welded onto the plate-shaped element 11. The pins 12 are
provided above two slits 14 which are provided on the central longitudinal axis of
the plate-shaped element 11. Furthermore, the plate-shaped element 11 comprises a
part 16 for making it easier to insert the anchor block into the ground.
[0055] A link 15 of a chain is placed around each of the pins 12. The links 15 fall partially
into the slit 14. The thickness of the link is almost the same size as the width of
said slit, so that the link can rotate only in the plane perpendicular to the pin
12.
[0056] The link 15 can form part of a chain which as a whole forms the pulling cable. It
is also possible to provide one link or a pair of links, in which case a pulling cable
of a different type, for example a steel cable, can be fixed on the then arising "short"
chain on the end lying away from the plate-shaped element.
[0057] One of the slits 14 advantageously runs to the edge of the plate-shaped element 11
(in the drawing slit 14 on the left-hand side). This makes it possible for the chain
lying on this side to lie substantially in the plane of the plate-shaped element 11
(dotted line in the drawing). As a result, during the pulling out of the anchor block
10 the chain and the plate-shaped element 11 will be substantially in line with each
other, with the result that the cross section of the combination of plate-shaped element
11 and link 15 in the direction of pulling out becomes smaller. Furthermore, the plate-shaped
element does not have the tendency to rotate during the pulling, and the tension in
the link 15 and the force exerted upon the pin 14 will be lower.
[0058] In the embodiment shown the pins 12 are provided on the side of the plate-shaped
element 11 where the pulling cables also extend. It is also possible to provide the
pins 12 on the other side of the plate-shaped element or in the plane of the plate-shaped
element. Instead of welding, it is also possible to connect the pins 12 to the plate-shaped
element 11 by use of a suitable method.
[0059] The anchor block 10 can be designed and/or used in the way described in the remainder
of this patent application.
[0060] Figure 5 shows an anchor block 20 according to the invention, which is used to anchor
a sheet pile wall 21. The sheet pile wall 21 comprises a number of sheet pile wall
planks 22, which form a sheet pile wall in the known manner. The anchor block is inserted
into the ground in the manner described earlier in the application and comprises a
plate-shaped element 23 and two pulling cables 24.
[0061] The pulling points/fixing points 25 by means of which the pulling cables are fixed
on the sheet pile wall 21 are advantageously placed at a greater distance from each
other than the dimension of the plate-shaped element 23, in other words the pulling
cables 24 diverge in the direction away from the plate-shaped element 23. An advantage
of fixing the pulling cables 24 on the pulling points 25 in this way is that a number
of sheet pile wall planks 22 can be fixed with a single anchor block. It is possibly
not necessary here to use a waling, since the anchorage gives sufficient support for
the - in this case three - sheet pile wall planks.
[0062] Another advantage of the method shown in Figure 5 for fixing the pulling cables 24
on the sheet pile wall 21 is that, since the pulling cable 24 lies outside the surface,
or projected surface, of the plate-shaped element 23, i.e. not on a line perpendicular
to the plate-shaped element 23, when the pulling cable 24 is pulled the tilting of
the plate-shaped element and subsequent removal of it from the ground will be made
even easier. The two pulling points/fixing points 25 in this case advantageously lie
outside the surface, or projected surface, of the plate-shaped element 23, so that
it is easily possible to pull out the plate-shaped element 23 with one of the two
pulling cables 24.
[0063] In an alternative embodiment it is also possible to leave more than one sheet pile
wall plank 22 between the sheet pile wall planks 22 on which the pulling cables are
fixed. It is then possible to span an even greater distance with a single anchor block.
If desired, a waling may be provided between the two sheet pile wall planks 22, on
which the pulling cables 24 are fixed in order to strengthen the anchorage even further.
[0064] For the sake of completeness, it is pointed out that the removable anchor block according
to the invention can be used both for temporary anchorage of an object (for a short
period) and permanent anchorage of an object (for a long to very long time). Even
in the case of permanent anchorage of an object it may in fact be desirable for the
anchor ultimately to be removed from the ground. It is therefore advantageous to use
the removable anchor block according to the invention. Furthermore, said anchor block
is quick and easy to insert into the ground, so that in both cases it is advantageous
to use it.
1. Removable anchor block for insertion into the ground for anchoring an object, comprising
a plate-shaped element having two or more fixing points for fixing pulling cables
on the plate-shaped element, characterized in that at least two of the two or more fixing points are provided substantially evenly distributed
around the circumference of the plate-shaped element, and in that the two or more fixing points are designed to be connected directly or indirectly
by means of the pulling cables to the object to be anchored.
2. Anchor block according to claim 1, in which the plate-shaped element has two fixing
points.
3. Anchor block according to claim 1 or 2, in which the plate-shaped element has three
fixing points.
4. Anchor block according to one or more of claims 1 - 3, in which at least two of the
two or more fixing points are provided near an edge of the plate-shaped element.
5. Anchor block according to one or more of claims 1 - 4, in which an edge of the plate-shaped
element is at least partially bevelled or sharpened in order to make it easier to
insert the plate-shaped element into the ground and/or pull it out of the ground.
6. Anchor block according to one or more of claims 1 - 5, in which the anchor block comprises
a connecting part which is suitable for connecting to an elongated pushing element,
in particular a pushing tube, by means of which the plate-shaped element can be pushed
into the ground in a direction substantially parallel to the surface of the plate-shaped
element.
7. Anchor block according to one or more of claims 1 - 6, in which the connecting part
is a projecting part of the plate-shaped element, which projecting part is complementary
to an end of the elongated pushing element.
8. Anchor block according to one or more of claims 1 - 7, in which the plate-shaped element
is substantially circular.
9. Anchor block according to one or more of claims 1 - 8, in which the plate-shaped element
is substantially rectangular, in particular square.
10. Anchor block according to one or more of claims 1 - 9, in which the dimensions of
the side or the diameter of the plate-shaped element lie in the region of 0.2 to 2.0
metres, preferably in the region of 0.4 to 1.0 metre.
11. Anchor block according to one or more of claims 1 - 10, in which the anchor block
comprises two or more pulling cables, each of which is permanently or detachably connected
to one of the two or more fixing points.
12. Anchor block according to claim 11, in which the two or more pulling cables are of
the same length.
13. Anchor block according to claim 12, in which the pulling cable is substantially in
the form of a chain.
14. Anchor block according to claim 13, in which a link of the chain is pivotably mounted
in a fixing point, which fixing point is in the form of a pin around which the link
is placed.
15. Anchor block according to one or more of claims 1 - 14, in which the two or more pulling
cables are pivotably fixed on the two or more fixing points in such a way that the
pivoting is possible only about an axis which is parallel to the plane of the plate-shaped
element.
16. Method for inserting a plate-shaped anchor block into the ground according to one
or more of claims 1 - 15,
characterized by the following steps:
- connecting the plate-shaped element to an elongated pushing element, in particular
a pushing tube,
- pushing the piale-snapea element into the ground,
- disconnecting the anchor block and removing the pushing element from the ground,
- bringing the anchor block into a desired position by pulling the two or more pulling
cables connected to the plate-shaped element in such a way that the plate-shaped element
tilts into the desired position, and
- connecting to the pulling cables the object which is to be anchored by the anchor
block.
17. Method according to claim 16, in which the two or more pulling cables are of the same
length, and in which the pulling of the two or more pulling cables is performed from
one pulling point, for example a hook.
18. Method according to claim 16, in which the two or more pulling cables are pulled in
two pulling points, the distance between the pulling points being greater than the
dimension of the plate-shaped element.
19. Method according to claim 16, in which the object to be anchored is a sheet pile wall
made up of two or more sheet pile wall planks, each of the two or more pulling cables
being fixed on a separate sheet pile wall.
20. Method for removing an anchor block according to one or more of claims 1 - 15, characterized by pulling one of the two or more pulling cables in such a way that the plate-shaped
element tilts and can be pulled out of the ground in a direction substantially parallel
to the surface of the plate-shaped element.