FR2801914A1 - Water retaining structure e.g. for collecting rainwater for subsequent release has layer of porous ducts able to support earth layer - Google Patents

Abstract

The structure (1), designed to trap water before it goes into a holder (5) which can be emptied gradually, has a layer (13) forming a chamber or a series of adjacent porous ducts (14) able to support the weight of a back-filled earth layer (3) covering it. The ducts are open at the bottom and semi-circular, arched or polygonal in cross-section, and are in two or more staggered layers. They can be made from concrete, pozzolana or expanded clay in sections weighing not more than about 20 kg.

Description

The present invention relates to a flow-water retention structure comprising a system for capturing water supplying a retention capacity and water retention systems. means of evacuation of the water thus captured.

It finds a particularly important, though not exclusive, application in the field of stormwater sanitation in urban areas.

Urbanization leads to waterproofing soils, which poses a problem of evacuation of rainwater in case of heavy falls, during showers or thunderstorms.

is already familiar with traditional techniques that consist mainly of oversizing the drain lines to accommodate maximum flow rates.

The cost of investments for the construction and installation of such large diameters is important. They also do not limit the pollution, rainwater is then completely rejected too quickly in the sewer system.

There are also techniques for locally storing rainwater and then gradually discharging it back to the sanitation facility or into the soil by infltrations. These techniques also have disadvantages.

When they are on the surface, they are unhealthy, stagnant water favoring for example the proliferation of mosquitoes.

When they are buried, they use costly storage systems of the polyethylene box type which certainly allow a good retention capacity and a gradual release at an acceptable rate, but which are also tedious to implement because requiring for example adjusted stacks.

In addition, these boxes are non-recyclable materials, whose durability is also not demonstrated.

The present invention aims to provide flow water retention structure better than those previously known to the requirements of practice, particularly in that it will allow to overcome these disadvantages by providing simple means, inexpensive and easy to put Manually operated by unqualified operators.

With the present invention it will be possible to obtain a capacity of retention and occupation of the structure by water up to 90 '95% of the corresponding volume in the soil.

Such a structure therefore has a maximum vacuum index, while allowing great maneuverability, by having a great lightness, and with a small footprint, and excellent resistance to chemicals, microorganisms and compression efforts.

For this purpose, the present invention proposes in particular a flow water retention structure comprising a water collection system supplying a progressively drainable retention capacity, characterized in that the retention capacity comprises at least one formed layer. at least one box defining a cavity or several adjacent pipes of porous material, said capacity being arranged to support the weight of a backfill field covering the capacity.

The structure may also be able to withstand rolling overloads or the like.

In advantageous embodiments, one and / or the other of the following provisions is also used.

the ducts or boxes made of porous material are open towards the bottom of the capacity; the ducts or caissons have a cross-section in the form of a semicircle or cocked hat; the pipes have a cross section in the form of a warhead; - the pipes or caissons are closed; - the pipes or caissons have a polygonal cross section; - the pipes are cylindrical; - The structure comprises at least two superposed layers of boxes or pipes, offset with respect to each other. This allows for example to form a honeycomb structure; the capture system comprises the backfill field covering the upper layer of caissons or pipes; the one or more layers of caissons or channels rest on a bed of lower shape, for example in contact with the ground via an interface membrane; the porous material is pozzolan concrete or expanded clay; - The pipes are formed of contiguous portions, and / or connected to one another, in the extension of one another.

Advantageously, the portions or boxes are of low weight, suitable for being moved manually by an operator, for example by means of an edge clamp, for example having a weight of less than 20 or 25 kg.

The present invention will be better understood from the following description of embodiments given as non-limiting examples.

The description refers to the drawings which accompany it in which - Figure 1 is a sectional view of a first embodiment of a retention structure according to the invention. - Figure 2 is a perspective view two superposed layers, staggered, a second embodiment of the invention with pipes having a section substantially in the form of cocked hat.

- Figure 3 shows, in perspective and in section, a third embodiment of the invention with cylindrical pipes.

- Figure ibis shows a connection means between two portions of cylindrical pipes of Figure 3.

FIG. 4 is a diagrammatic section showing a fourth embodiment of structure piping according to the invention, having an ogival-shaped section.

- Figure 5 shows a fifth embodiment of pipe of a structure according to the invention in the shape of an inverted U.

- Figure 6 shows in exploded and partial perspective a sixth embodiment of a structure according to the invention with boxes.

Figure 1 shows a flow water retention structure 1 (arrows 2) in the soil 3 comprising a water capture system 4 and a water holding capacity 5.

In this embodiment, there is provided means 6 for discharging water, formed by a fully porous lower channel 7, of small diameter, for example cylindrical diameter of 20 cm, arranged to evacuate the water to a reservoir or recovery basin (not shown).

The emptying of the capacity can also be done simply by the lower layer of pipes or by a bed of draining material.

 Also depending on the terrain, 1 evacuation can be done in a distributed way on a part or on the whole surface of the capacity, by progressive infiltration into the ground under the capacity 5.

The capture system is for its part formed for example by a permeable soil 9, and by one or more collecting wells 10 of water recovered from the impervious roadway 12.

In the embodiment more particularly described here, the retention capacity 5 comprises several parallel layers 13 of pipes 14, for example four superimposed layers, porous material such as pozzolan concrete.

The pipes are formed by tunnels in the form of half-cylinders, whose opening directed downwards, for example of thickness 3 and horizontal diameter 20 cm.

Each layer is offset with respect to each other, so that the ends of the edges of each upper half-cylinder rests on top 16 of a half-cylinder of the lower layer.

In the embodiment described with reference to FIG. 1, where it has been assumed that the bottom floor of the excavation can be permeable, the lower layer 13 rests on a permeable membrane 17 below which the evacuation pipe is placed. 7.

But the membrane placed in the bottom of the excavation can also be sealed, in which case it is the lower bed of the porous structure which serves as a drain for example.

The pipes thus arranged provide in their inner part an empty volume or water retention capacity of the order of 90 to 95% of the total capacity.

The upper layer of pipes 13 supports the weight of the embankment land 18 forming the lower part of the soil 9, possibly planted with plants 19 and / or other loads such as rolling loads.

FIG. 2 shows a structure according to another embodiment of the invention comprising ducts 21 of section in the form of a cocked hat, obtained from identical elements 22, of low weight, adjacently juxtaposed to prevent the earth embankment penetrate into the interior 23 of said pipes.

More precisely, the elements 22 have an example of a half-cylindrical shape terminated on lower edges by a recess or projection 24 in the form of an elongated rim, the element being of dimension 50 cm × 60 cm × 25 cm, allowing a vacuum index between 0.8 and 0.9. The rainwater 25 passes through the porous walls of the pipes and joins the bottom of the excavation, the lower layer of the soil 26 being here substantially permeable or formed by a permeable layer that is flat, horizontal, above an impermeable layer.

FIG. 3 shows another embodiment of a structure 29 according to the invention, with tubular ducts 30, this time formed of tube portions 31, for example connected between them by a known system 32 of the mortise tenon FIG. 3bis), which allows a mechanical rigidity between portions of pipes.

The water 33 passes through the walls of the porous material in India, and joins the bottom of the excavation for evacuation.

The structure supports an embankment layer 34, tubes being inserted into the earth 35 and delimiting a void space of about 90% of the volume occupied by the pipes.

FIG. 4 schematically shows another embodiment of structure 36 with the channel 37 sections in the shape of an ogive.

FIG. 5 shows a fifth embodiment of the structure 38 comprising two layers 39 of channels 40 in the shape of an inverted U, the layers being arranged in staggered rows on one another, to form a honeycomb structure which is extremely resistant to compression and on which can be placed an embankment 41 of significant weight.

FIG. 6 shows in perspective a stack of caissons 43 of inverted U-shaped section with a flange, with slightly inclined U-sides, for example, an overall width at the base of 50 cm, a height of 50 cm and a thickness. porous wall of 5 cm.

The box thus defines a cavity open to the bottom of substantially rectangular or frustoconical shape.

The method of forming a structure according to the invention will be described below.

After carrying out a search corresponding to the overall volume of the required retention capacity, a waterproof membrane is eventually put in the bottom of the excavation to prevent the infiltration of the water from the capacity into the water table (if one tries to protect the web), then a geomembrane (not shown) to avoid punching.

The layers of pipes or caissons are then constructed by juxtaposition and stacking on several levels.

Then covering the whole with a backfill layer, possibly using grid to resume horizontal tensile forces, and a wearing course if necessary. We will now describe the operation of the retention structure according to the invention with reference to Figure 1.

During heavy rains, the water is rapidly infiltrated into the soil 9 and / or flows through the well at a high flow rate because it collects runoff water with a large impermeable surface. diameter the direct infiltrations in the ground in not being enough to evacuate the sudden flow, water rises in the structure (level 42).

Then when the storm or rain stops, water flows slowly to its maximum flow in line 7, until complete evacuation of the temporarily stored water volume, thereby regenerating the available storage capacity volume.

It goes without saying and as it follows from the foregoing, the present invention is not imitated to the embodiments more particularly described. On the contrary, it encompasses all variants, especially those in which the section of the pipes is triangular, where another porous material is used as an example of expanded clay concretes, recycled glass ball concretes, or those where the capacity is mounted on a substantially permeable slope.

 The structure according to the invention is indeed adaptable on any type of terrain, sloping, flat, uneven, etc.

Claims (12)

<U> CLAIMS </ U> A flow water retention structure (1, 20, 29, 36, 42) comprising a water collection system supplying a progressively drainable holding capacity (5), characterized in that the retention capacity comprises at least one layer (13) formed of at least one box (43) defining one or more adjacent channels (14, 21, 30, 37, 40) of porous material, said capacity being arranged to support the weight of a land (3, 34, 41) embankment covering the capacity. 2. Structure according to claim 1, characterized in that the pipes (14, 21, 37, 40) or boxes (43) of porous material are open down the capacity. 3. Structure according to claim 2, characterized in that the pipes (14, 21) or caissons (43) have a cross section in the form of a semicircle or gendarme hat. 4. Structure according to claim 2, characterized in that the pipes (37) have a cross-section in the form of ogive. 5. Structure according to claim 1, characterized in that the pipes (30) or caissons are closed. 6. Structure according to any one of the preceding claims, characterized in that the pipes (40) or caissons (43) have a polygonal cross section. 7. Structure according to claim 5, characterized in that the pipes are cylindrical. 8. Structure according to any one of the preceding claims, characterized in that it comprises at least two superposed layers of caissons or channels offset with respect to each other. 9. Structure according to any one of the preceding claims, characterized in that the capture system comprises said embankment land (3, 34) covering the upper layer of caissons or pipes. 10. Structure according to any one of the preceding claims, characterized in that the layer or layers of boxes or pipes rest on a bed of lower shape, in contact with the ground. 11. Structure according to any one of the preceding claims, characterized in that the porous material is pozzolan concrete or expanded clay. 12. Structure according to any one of the preceding claims, characterized in that the boxes or pipes formed of contiguous portions, are such that said boxes or said portions are each less than the weight of about 20 kg.