[0001] This invention relates to prefabricated articles in reinforced concrete for making
circular tanks set in or out of the ground.
[0002] More specifically, the method is concerned with blocks with arc cross-sections and
lateral self-centring joints. The blocks are laid side by side to form the vertical
circular wall of the tank and are held together by tension cables placed around the
outside of the walls of the tank.
[0003] Externally, the blocks have ribbing shaped for the seatings of the tension cables.
The cables are thus positioned exactly during assembly and afterwards remain hidden
from view.
[0004] There are numerous sectors which may require tanks to be constructed, especially
of the above-ground type which can be produced with prefabricated parts and are thus
cheaper, easier and quicker to construct.
[0005] Tanks of this kind, for example, are often used in agriculture for water or detritus
storage, or in industry for filters or similar such purposes.
[0006] Generally, these tanks are circular in shape because it is this form which ensures
a more uniform distribution of internal forces and pressure, takes up the least surface
area in relation to capacity, and is easier rig up and construct.
[0007] Common are tanks constructed out of the ground with a number of arc-shaped blocks
set out side by side and held tightly together by tension cables which run around
the whole perimeter of the tank.
[0008] For the construction of this type of tank in particular, an iron beam is first set
up or a mounting with means of attaching the tension cables, fixed to appropriate
previously-prepared foundations. The various panels are then positioned side by side,
held in place by bracing elements.
[0009] Once the blocks have been positioned the tension cables are wound around the tank
with their ends anchored to the iron beam for tightening to be carried out.
[0010] Only after this operation is it possible to remove the bracing elements which hold
the panels in place initially.
[0011] This system is, however, quite laborious, due to the fact that one has to set up
and then remove the bracing elements. Furthermore, the cables, which remain exposed,
are subject to corrosion if, for example, the tank is situated in a saline-rich or
a polluted environment, as well as being easily accessible to acts of vandalism. The
aesthetic appearance of these cables is also rather unpleasant.
[0012] To avoid these inconveniences the invention in question proposes manufactured articles
and a related construction method for making circular tanks both out of and in the
ground. Each of these arc cross-section manufactured parts has a self-centring joint
externally and ribbed channelling for the tension cable seatings which are thus automatically
positioned and hidden from view.
[0013] This seating can then be filled with mortar or any other suitable material to protect
the cables from external agents.
[0014] The invention will now be described in detail with particular reference to the figures
enclosed which illustrate the following:
Figures 1,2 and 3 illustrate respectively the facade, the vertical section and the
plan of a tank constructed following the design of the invention;
Figures 4,5,6 and 7 illustrate respectively the lateral and frontal views, the vertical
section and the plan of a block according to the invention;
Figure 8 is a detail of the connection between two blocks;
Figure 9 illustrates a detail of the panel;
Figures 10,11 and 12 illustrate respectively the frontal view, the lateral view and
the plan of the terminal block of the tank;
Figures 13 and 14 are the lateral view and the plan of a plinth for the positioning
of the terminal block;
Figures 15 and 16 show a general view and a detail of a further more popular version
according to the invention.
[0015] With reference to Figures 1 and 3, a tank out of the ground is created by the combination
of a number of blocks and panels (1), joined and fixed at their extremities to a head
element (2) which is mounted on a foundation plinth (3).
[0016] Each of these blocks has an arc cross-section (Fig. 7) viewed from above and has
the sides 4 and 5 shaped respectively male and female for a self-centring joint with
the adjoining panels.
[0017] A characteristic of the invention is that each of these blocks has a series of essentially
horizontal ribbing, illustrated in detail in Figure 9.
[0018] The ribbing (6) creates a raised border or parapet (7) on the external part of the
block thus forming a seating between the wall of the panel and this border for the
tension cables (8). The upper wall (9) of each rib is not flat but is raised in the
centre so that the bottom of ribbing slopes from the centre outwards.
[0019] The ribbing (6) is slightly shorter than the panel itself so as to leave a small
space between adjacent ribbing when construction is complete, as shown in Fig. 8.
The distance between the ribbing is not constant. Lower down on the panel the ribs
are closer together, where the hydrostatic pressure exerted on the walls is greater
and where the cables around the panels must thus be closer together. By cutting blocks
off at the base, one can obtain tanks of different heights.
[0020] The head element (2) (Figs. 10,11 and 12) also has an arc plan cross-section. but
without ribbing. It is thicker than the other blocks, essentially equal to the thickness
of the panels (1) plus that of the ribbing, with the central part enlarged to contain
the ends of the cables (8) to be tightened, giving a firm anchorage.
[0021] The head element (2) is mounted on a plinth (10) with a seating (11) shaped to allow
(1) the insertion and fastening of the element (2).
[0022] For the assembly of the tank, a foundation kerb and plate are set out, on which the
various blocks are placed. The plinth is then put in position and the head element
assembled, fixing it temporarily with two wedges or similar objects.
[0023] The various blocks are then put in place side by side bringing the lateral walls
together and fixing them, again temporarily, with a gusset plate, a clamp or similar
system, with the first and the last block fixed to the head (2).
[0024] During assembly a sealing gasket (10) (Fig. 8) is placed between adjacent blocks,
made of Neoprene or similar material.
[0025] At this point the tension cables can be put in place. They are simply inserted in
the ribbed seatings (6) with the respective borders (7) and anchored at their ends
to the head element (2).
[0026] This operation is made easier by the fact that the cables only have to be laid on
the ribbing. They are thus already exactly positoned for tightening without having
to use support elements or having to check and make adjustments to their positon.
[0027] Once the cables have been tightened and anchored the gusset plates which held the
blocks together can be removed and finishing operations carried out - e.g. applying
a layer of sealing glue (11) along the internal edges of the blocks (Fig. 8), filling
the seatings with mortar or similar material thus protecting the cables from possible
damage and from atmospheric weathering.
[0028] If, on the other hand, the space around the cables is not filled, then the sloping
of the bottom wall (9) of the seating makes for rapid drainage of water which is deposited
on the outside through the space left free between the ribbing. If particularly rigid
panels are requested then vertical ribbing (12) (Fig. 15) can be provided in the external
wall with holes through which cables may pass.
[0029] The advantages of these newly-invented products are various. During production it
is possible to make blocks of varying heights using the same caisson, simply by inserting
partitions.
[0030] Assembly is much simpler and more practical. It is not necessary to use bracing elements
for the temporary attachment of the panels and it is enough to just place the cables
in the seating which then position themselves exactly on tightening.
[0031] Water drainage is improved in the cable seating area, which can also be protected
with a filling of mortar or other suitable material.
[0032] Finally, the appearance of the tank is improved with the cables hidden from sight.
[0033] Experts in the sector may foresee any number of modifications and variations which
must, however, be held to be included in the scope of the present invention.
1. Method for the creation of circular tanks, characterized by the following phases:
- positioning of a foundation plinth and a head block for the attachment of the tension
cables;
- positioning of a series of blocks or panels for the construction of the walls of
the tank, fixing them with temporary, removable means and with these panels providing
seating on the external surface for tension cables;
- positioning of tension cables in the said seating;
- the tightening of these cables and their attachment to the head block;
- the removal of the temporary connection devices between the panels;
2. Manufactured parts for constructing circular tanks out of the ground, made of blocks
with an arc plan cross-section and external ribbing for tension cable seating.
3. Manufactured parts as described in claim 2, in which said ribbing has a raised external
edge, the height of which is greater than the diameter of the cable.
4. Manufactured parts as described in claim 3, in which said ribbing is shaped into a
channel.
5. Manufactured parts as described in claims 2 and 4, in which the said seatings for
the cables are sloping, with an open section at the end for water drainage.
6. Manufactured parts as described in claim 5 in which open sections are formed by making
the length of the ribbing slightly less than the width of the panel.
7. Manufactured parts as described in any of the claims from 2 to 6, in which the distance
between the ribbings varies vertically on the panel, being closer together lower down,
where there is greater hydrostatic pressure.
8. Manufactured parts as described in any of the claims from 1 to 7, in which there are
also vertical ribs to increase rigidity, the ribbing having holes through which the
cables which lodge in the channels may pass.
9. Tanks made with manufactured parts as described in claims 2 to 8.
10. Tanks as in claim 9, with a band of flexible sealing material inserted between adjacent
panels.
11. Prefabricated circular tanks made by the method described in claim 1.