Note: Descriptions are shown in the official language in which they were submitted.
CA 02752766 2011-09-16
ANTI-FLOTATION ANCHOR FOR UNDERGROUND TANKS
Field of the Invention
The invention relates primarily to an anchor that prevents the unwanted upward
movement of a buried tank due to buoyancy forces which are present during high
water
table conditions.
Background of the Invention
A tank buried underground displaces the same volume of earth as the tank
itself,
effectively creating a void in the earth equivalent to the tank volume. During
high water
table conditions, especially when the tank is empty, the tank acts as a
barrier preventing
the groundwater from filling the void. This results in the tank being
submerged
underwater with buoyancy forces acting upon it. If these buoyancy forces are
not
counteracted, the tank may float to the surface.
One solution to counteract these buoyancy forces is to construct the tank
heavy enough
so that the weight of the tank will be sufficient to counteract the buoyancy
forces. But
this creates a tank that is both heavy and dangerous to install.
Another solution is to create a lighter tank, which is easier and safer to
install, and with
the aid of tethers, anchor it to a sufficiently heavy mass thusly creating the
necessary
weight. The mass may be bead rock, or an adequate concrete slab among others.
However, depending on location, bead rock may not be practically available,
and a
concrete slab represents a costly and time-consuming alternative.
CA 02752766 2011-09-16
Another solution is to generate the necessary weight by attaching said tethers
to
readymade curbs. This caries the benefit of being faster to install but due to
weight
requirements, still represents safety risks.
Our solution is to utilize tethers and hollow bucket-like curbs with tether
attachment
points with each curb light enough to allow ordinary equipment or perhaps one
or two
men to place and install, and upon filling the bucket-like curb with backfill
material
produce the necessary weight to counteract the buoyancy forces.
Brief Description of the Drawings
Figure 1: An isometric representation of, from bottom to top, anchor body,
hooks.
Figure 2: An isometric section view of, from bottom to top, re-enforcing
structure, anchor
body, hooks attached to re-enforcing structure.
Figure 3: An isometric representation of anchors in use retaining a
cylindrical tank, from
bottom to top, anchor body, anchor hook, strap hook ring, strap, underground
tank.
Figure 4: An isometric representation of stacked anchors, from bottom to top,
anchor
body, anchor body, hook.
Description of the Invention
Figure 1 shows one embodiment of an anchor having an upward-facing cavity and
at
least one strap attachment point. The upward facing, and outward flaring
cavity
perimeter wall (1) together with the base wall (2) define a volume that when
filled with
material of given density create an anchor having a substantially greater
combined
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CA 02752766 2011-09-16
weight then the material weight used to manufacture the anchor itself.
Further, the
upward and outward flaring walls (1) together with stacking stops (3) allow
multiple
anchors to stack on top of each other as shown in figure 4, without resting on
and
damaging the strap hooks (4). As illustrated in figure 2, the upward and
outward flaring
walls (1) and base wall (2) are manufactured from concrete but may be
manufactured
using fiber re-enforced concrete, fiber reinforced plastic, plastic, steel et
cetera. For
added strength, a steel re-bar (5) enforcing system is used to which stainless
steel
anchor hooks (4) are attached. But the re-enforcing system may be manufactured
using
other materials such as other metals, meshes, fibers, fiber re-enforced
plastic et cetera.
Figure 3 illustrates the anchor(s) installed and retaining a tank (20) by
connecting
anchors placed on opposite sides of the tank (20) and straps (11) having strap
hook
rings (10) attached to each end placed over the tank (20). Each strap hook
ring (10) end
is then hooked onto the anchor hook (4) on opposite sides of the tank (20). By
filling
each properly-sized anchor with a predetermined amount of material, the tank
becomes
adequately anchored against flotation forces.
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