Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a device for temporarily
sealing dormant boreholes, and in particular boreholes that
are used in blasting operations.
In order to carry out blasting operations in rock,
arrays of vertical boreholes, typically 50ft deep, must be
drilled into the rock. For a typical blast, at least ten
holes will be required, making a total drilled footage of at
least 5000ft. As the maximum that can be generally be
drilled in one day is about 400ft, it can take at least
twelve days to prepare for a blast. During this time the
drilled holes tend to fill up with silt and water.
In the prior art, it is common practice to plug the
boreholes temporarily until all are ready for a blast. This
is usually done with inverted cones, which are pushed into
the upper ends of the boreholes. The cones are then removed
prior to use.
The problem with this procedure is that the interior
walls of the boreholes are rough and the cones do not make a
good seal. As a result, water still leaks into the holes.
Also, especially in snow the cones can be hard to find.
Various techniques are known in the art for capping
wells and the like, but the devices employed cannot
generally be easily removed or are too expensive for
blasting holes since there may be substantial number of
holes in a small area.
An object of the invention is to provide a convenient,
low-cost device suitable for temporarily sealing boreholes.
According to the present invention there is provided a
device for temporarily sealing dormant boreholes, comprising
a generally cylindrical body member for insertion into a
borehole having an irregular interior surface, said body
member being of a stiff resiliently deformable material; and
shank protruding means extending longitudinally through said
body member, said shank means above said terminating in a
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215677~
handle; whereby said body member can be manually forcibly
fitted into said borehole and removed therefrom with the aid
of said handle.
The cylindrical body member preferably lies between
upper and lower end plates at respective opposite ends of
said body member. These are desirable to assist in pushing
in the device into the borehole and removal therefrom. Upon
insertion the upper plate pushes the cylindrical body
downward, and upon removal the lower plate pushes it upward.
The cylindrical body can be in the form of stacked sections.
Also, it is understood that the body member can have
any generally cylindrical shape, including for example
polygonal shape.
The above device can be manufactured in quantity at
relatively low cost. It can be easily inserted into the
boreholes after drilling and removed prior to blasting
simply by pulling on the handle. The device is then ready
for re-use.
The deformable material is preferably a closed cell
foam.
In a preferred embodiment a flag projects upwardly from
the body to aid in visibility.
The invention will now be described in more detail, by
way of example only, with reference to the accompanying
drawings, in which:-
Figure 1 is a cross section through a borehole sealingdevice in the relaxed condition;
Figure 2 is a section through the device inserted into
a borehole;
Figure 3 is a cross sectional view of the handle;
Figure 3a shows a detail of the end of the shank of the
handle perpendicular to the view in Figure 3;
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21~6779
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Figure 4 shows a single cylindrical section mounted on
the handle of Figure 3;
Figure 5 shows a stack of cylindrical sections;
Figure 6 shows an extension section of the shank;
Figures 6a and 6b show details of the end of the shank
shown in Figure 6;
Figure 7 shows the lower end of the shank with a
cylindrical section mounted thereon; and
Figure 8 shows a lower end plate for the shank.
The borehole sealing device shown in Figure 1 comprises
a shank 1 connected through a force-fit coupling 2 to a T-
shaped handle 3.
The shank 1, made of I-section HDPE (High Density
Polyethylene) plastic, extends longitudinally through a
central aperture a cylindrical body member 4 consisting of
four stacked cylindrical sections 4a, 4b, 4c, 4d. Circular
end plates 5, 6 are attached to the shank 1 at opposite ends
of the body 4. Although referred to as cylindrical, it is
understood that said sections can have any generally
cylindrical shape, and, for example, could be polygonal in
cross section.
The cylindrical sections 4a, 4b, 4c, 4d consist of a
stiff resiliently deformable closed cell material, for
example, the polyethylene foam cell sold by Dow Chemical
Corporation with a density of 1.4 to 1.9 lbs.
A flag 7 is insertable into a small receiving recess in
the upper plate 5. This can be screwed in or force-fitted,
for example.
In use, after drilling a borehole the user takes one of
the sealing devices and adds the appropriate number of
sections for the type of borehole. He merely then grabs the
handle 3 and rams body member 4 into the top of the hole.
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21~6~79
The material forming the sections 4a, 4b, 4c, 4d
deforms upwardly due to frictional contact against the walls
leaving a small space _ above the lower end plate 6. The
compression of the cylindrical body 4 causes it to become
forcibly fitted against the interior wall 10 of the borehole
9.
The handle 3 can then be removed or left in place as
desired.
The shank 3 can be easily extended by adding new
sections as desired.
Figures 3 to 7 shows a preferred embodiment of the
handle and shank, which comes in engageable sections.
In Figure 3, the upper circular end plate 5 of HDPE iS
integral with the first section of the shank 1, also of
HDPE, whose lower end has notches 11 formed in the flanges
15 of the I-section flank. As shown in Figure 4, the upper
cylindrical section 4a is mounted on this first section of
the shank in abutting relationship with the upper plate 5.
Lower plate 6 of HDPE has a keyhole recess 6a as shown
in Figure 8. After the cylindrical section 4a has been
mounted on the shank 1, the lower end plate 6 is force-
fitted onto the shank with the edges 6b of the slightly
inner enlarged inner portion of recess 6a engaging the
notches 11 of the shank 1. As a result the shank 1 is held
in place. The plug as shown in Figure 4 can be used for
certain applications.
Additional sections can be added, as shown in Figure 5,
by adding additional extension shank sections 20, such as
shown in Figure 6. An integral circular plate 6 is mounted
on each shank section 20, which has a lower end similar to
the lower end of the shank 1 shown in Figure 3 with similar
notches 11. The upper end of the shank section 20 has an
arrowhead shape 13 formed by a beveled tip on flanges 15 of
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the I-section shank 1. A longitudinal recess is formed in
web portion 16 of the upper end of I-section shank.
In order to engage the handle section 1 and an
extension section as shown in Figure 6, the shanks are
rotated so that longitudinally they lie 90 apart relative
to each other. They are then pushed together so that the web
16 of the upper section is accommodated in the recess 17 and
that the wing portions 18 of the arrowhead 13 deform and
become engaged in the recesses 11 of the upper section. As
many extension sections 20 as desired can be added in this
way, each being rotated 90 about its longitudinal axis
relative to the previous section.
Figure 5 shows a stacked device inserted into a
borehole in rock stratum 27. In Figure 5, there is no plate
6 between the first and second sections 4a, 4b because the
upper end of the extension piece 20 is engaged directly into
the lower end of the shank 1 so that the first two
cylindrical sections abut. Because of the rotation of the
shank from one piece to the next, only the flange portion 15
of the extension piece is visible in Figure 5 in the section
4b. Of course a plate 6 is present under this section
because it is integral with the shank of the extension piece
as described. A final section is then added with the aid of
a third extension piece 20.
The described device is very convenient in the field.
It can conveniently be made shorter or longer depending on
the application. It is lightweight and does not take up a
lot of space, especially as the components can be stored
separately and assembled in the field as needed without any
special tools.
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