WO2021234175A1

WO2021234175A1 - Device for retaining waste at the outlets of discharge channels, outflows, nozzles, pipes and gulleys, and method for the custom design of such a device

Info

Publication number: WO2021234175A1
Application number: PCT/EP2021/063725
Authority: WO
Inventors: Stéphane ASIKIAN; Sébastien AUGY
Original assignee: Eurofilet France
Priority date: 2020-05-21
Filing date: 2021-05-21
Publication date: 2021-11-25
Also published as: FR3110611B1; EP4153341A1; FR3110611A1

Abstract

Device (10) for retaining waste (13), having a main net (11) and at least one fastening means that is able to fasten an opening (15) of the main net to a solid support, said opening surrounding an outlet (5) of a rainwater network such that all of the water flushed through the outlet (5) passes through the net. According to the main feature of the device, the strength of the main net (11) is such that it can support the limit tensile force corresponding to the weight of the water falling into the main net (11) filled with waste (13) if a maximum flow rate of water arrives at the outlet, the strength of at least one fastening means being designed as a function of this limit tensile force and of the strength of the main net (11) and to be less than this limit tensile force in order that the retaining device (10) detaches from its support when this tensile force is reached and thus to avoid obstruction of the rainwater outlet (5) and flooding of the parts situated upstream of the retaining device (10). The net (11) has a flared shape such that, between its opening (15), through which the water filled with waste passes, and the face of the bottom (14) of the net, the passage surface inside the net, also designated flow cross section, increases in a ratio of between 1.5 and 2.5.

Description

Device for the retention of waste at the outlets of outlets, outlets, nozzles, pipes and outlets and custom design process for such a device

Technical field of the invention

The present invention relates to the technical field of devices for the retention of solid and polluting materials contained in rainwater collection networks, which use the gravitational force of these networks, and relates in particular to a retention device making it possible to retain the waste at the outlets. outlets, outlets, nozzles, pipes and outlets and also relates to the custom design process of such a device.

State of the art

There are many systems to eliminate the pollutants contained in rainwater and thus avoid polluting the natural environments in which this water is discharged. Such systems can include, for example, collection baskets provided with several filter screens of different mesh sizes. These baskets are made from rigid wire mesh. They are usually permanently installed and have an end door to be emptied. Such a system is described for example in document EP0882161.

A device for separating the solids conveyed by a wastewater and / or rainwater effluent described in document FR2811691, comprises a removable basket which can be handled by a single person. This device also comprises, as in the first cited document, a sieve of rigid material which has the advantage of not breaking in the event of heavy precipitation. However, in the event of heavy precipitation and to avoid clogging of the device, the excess water can overflow by passing over the basket and thus, all of the water loaded with pollutants does not pass through the filtering device, which has the drawback of no longer fulfilling the role of depolluting agent. Application US Pat. No. 6,517,709 describes a retention bag placed at a vertical water outlet such as a drain, the bag is contained in a retention basin and may comprise two layers. The bag inlet being installed around the wastewater outlet, all waste and pollutants contained in the water are captured by the bag. However, the drawback of such a device lies in the fact that once the bag is filled with solids, the shape and the arrangement of the bag are not intended to avoid or delay the effect of clogging and plugging. the outlet of wastewater and therefore the risk of overloading the network. Consequently, unless the bag is emptied very regularly, the risk of flooding the land located upstream of the water outlet is very real when the level of solids in the bag has reached the inlet of the bag. This risk is greatly increased in the event of heavy rainfall.

In addition, none of the devices described in the prior art provides for a dimensioning of the retention device adapted to the site on which it is to be installed and none of the devices mentioned describes means of securing in the event of heavy rainfall and sudden increase. of water flow.

Disclosure of the invention

This is why the aim of the invention is to overcome these drawbacks by providing a device with a high capacity for retaining pollutants at the outlet of a water pipe, versatile and adaptable to all types of site, sized to delay the clogging of the materials at the outlet and the plugging effect and comprising securing means to prevent flooding of the land situated upstream. Another object of the invention is to provide a method of tailor-made design of such a device.

The object of the invention is therefore a waste retention device comprising a main net and at least one fixing means capable of fixing an opening of the main net on a solid support, said opening surrounding an outlet of a network of storm water so that all water discharged from the outlet passes through the net. According to the main characteristic of the device, the resistance of the main net is such that it can withstand the limit tensile force corresponding to the weight of the water falling into the main net. filled with waste in the event of a maximum water flow rate reached at the outlet, the resistance of at least one fixing means being dimensioned according to this limit tensile force and the resistance of the main thread and to be less than this limiting tensile force so that the retention device detaches from its support when this tensile force is reached and thus prevent the obstruction of the rainwater outlet and flooding of the parts located upstream of the retention device.

Another object of the invention is a method of designing a made-to-measure retention device, comprising the following steps a) and b): a) Design of a main net comprising an opening intended to be fixed around it. an outlet of a storm water network so that all the water rejected by the outlet passes through the main net, b) Design of at least one means of fixing the retention device capable of breaking in case of a tensile force on the main net greater than a limit tensile force corresponding to the weight of the water falling into the main net filled with waste in the case of a maximum water flow rate reached at the outlet of water networks rainy waters. Brief description of the figures

The aims, objects and characteristics of the invention will emerge more clearly on reading the following description made with reference to the drawings in which:

[Fig. 1] is a schematic perspective view of the device according to the invention,

[Fig. 2a] shows a first schematic front view of the device according to the invention,

[Fig. 2b] shows a second schematic front view of the device according to the invention, [Fig. 2c] shows a schematic front view of the device according to an alternative of the invention,

[Fig. 3] shows a schematic perspective view of the device according to the invention provided with means to prevent backflow, [Fig. 4] represents a schematic front view of the device according to the invention of FIG. 3,

[Fig. 5] shows an alternative embodiment of the device according to the invention.

Detailed description of the invention.

According to FIG. 1, the device according to the invention is a device with a large retention capacity 10 for polluting materials comprising mainly a main net 11 for trapping the solids contained in the rainwater from an outlet 5 generally placed in a medium. natural, such as in terrestrial, aquatic, underwater, maritime or fluvial environments. The collection network can be a unitary or separate network, that is to say contain only rainwater or rainwater mixed with wastewater. Exit 5 may be an outfall, an outlet, a storm weir, a pipe, a nozzle or an inlet. The outlet 5 is generally located in front of a flow ramp 6. The net has an opening 15 adapted to come to be fixed around the outlet 5 so that all the solids contained in the water at the outlet 5 fall into the outlet. the net. Obviously, only solids larger than the mesh size of the net are retained by the net. The net has the shape of a truncated pyramid with a square or rectangular base, the opening of the net corresponding to the small base of the pyramid, the bottom of the net 14 corresponds to the large base of the pyramid. The length of the net corresponds to the height of the trunk of the pyramid. This shape is related to the method of making the net, but generally the shape of the net is such that it forms a trap and the area of the bottom section of the trap is greater than the area of the entry section. The section ratio is between 1, 5 and 2.5. This has the advantage of directing the waste directly to the bottom of the net and preventing it from getting stuck and forming plugs in the net section. On the other hand, the net thus has a strong propensity to expand in width. In the case of an inlet section and a circular bottom, the net has the shape of a truncated cone.

In Figure 1, the pyramidal shape of the net is intentionally represented as if it were rigid, for a better understanding. However, the net is made of rope stitches and once in place, the net follows the relief of the terrain. The net therefore has a flared shape so that between its opening 15 through which the water laden with waste enters and the face of the bottom 14 of the net, the passage surface inside the net also designated by passage section, increases in a ratio between 1, 5 and 2.5. This characteristic has the advantage of increasing the filling time of the net compared to a net of the same length but of constant passage section. The shape of the net makes it possible both to delay the moment when the net will be clogged while ensuring the circulation of fluids, and a high capacity for waste retention: of the order of 3 m ³ for the standard version. The length of the net is greater than or equal to 1.5 times the width of the bottom 14 so as to promote the distribution of waste.

The shape of the truncated pyramid net is therefore derived from a straight pyramid, with a square base or a rectangular base. The four lateral faces of the trunk of a pyramid are therefore isosceles trapezoids which are all identical in the case of a pyramid with a square base and two by two identical in the case of a pyramid with a rectangular base, the identical faces being opposite the one from the other. The lateral faces of the trunk of a pyramid are therefore defined by the height of length L, the angle a (alpha) and the angle 6 (beta) made by the height of the identical trapezoids two by two with their sides not parallel. The dimension of the thread 11 is therefore defined by its length L, the length of the edges a and b of its opening 15 and by the angles a and 6. The angles a and 6 are always chosen not to harm. Indeed, if the angles a and 6 are harmful, the volume shape of the main thread 11 has a constant passage section. The net 11 is made from a cord in a hydrophobic material, of low elasticity and resistant to ultraviolet radiation. The material used for the rope is preferably polypropylene but a material of equivalent characteristics could be used. The diameter of the rope is chosen to make the main net 11 resistant to the weight of the water falling into the net filled with waste in the event of a maximum water flow at outlet 5. The diameter is generally between 6 and 16 mm and preferably between 8 and 12 mm. According to a preferred embodiment of the invention, the nodes of the mesh of the net which constitute the walls of the net are symmetrical nodes. The knot used for the mesh of the net is of the Carrick knot type because it has the advantage of offering homogeneous resistance in the four strands coming out of it, due to its symmetry. The meshes of the net are preferably of square shape with a size between 150 x 150 mm for the standard version and 100 x 100 mm for the reinforced version.

According to a preferred embodiment of the invention, the retention device 10 comprises a second net 21 placed inside the first and main net 11 and of identical shape thereto. The characteristic dimensions of the second thread 21 are those of the main thread 11 increased by 3% to 10% and preferably by 5% so that it perfectly matches the shape of the main thread. On the other hand, the advantage of oversizing the second net 21 relative to the main net 11 prevents the second net from playing a resistant role that would be added to that of the main net 11. Only the resistance potential of the main net 11 is thus used for all of the two nets and only the waste retention function is used for the secondary net.

The second net 21 has a retention mesh finer than that of the first net in order to retain smaller waste. The second net can be a net whose mesh size is between 14mm and 50mm in order to retain macro-waste. The second net can also be made of millimetric meshes of the order of 200 microns in order to retain micro waste. The assembly of the two nets 11 and 21 ensures the retention of all the micro and / or macro waste larger than the meshes of the second net 21 located inside, flowing over the rainwater network and passing via the outlet 5. The retention device is fixed to a solid support by means of a first fixing means which connects the main net 11 to the support. This support is generally the wall surrounding the rainwater outlet. According to an alternative embodiment, the solid support can be an adaptable fixing gantry which is itself fixed to the ground and / or to the sides so as to surround the outlet 5 of rainwater. The portico is generally U-shaped.

The retention device comprises means for securing and protecting against flooding. Indeed, in the event of rain episodes after a period of drought, for example, the net will quickly fill with waste. If the weather conditions deteriorate, the net can reach its maximum retention capacity before the handlers pass through for its emptying and end up clogging and blocking the rainwater outlet, which risks quickly creating flooding on the land located in upstream. This is why according to a preferred embodiment of the invention, the first fixing means of the retention device is composed of two rigid parts linked together, one part of which is designed to disconnect from the other part in the event of tensile force on the main net 11 greater than a limit tensile force corresponding to the weight of the water falling into the net filled with waste in the case of a maximum water flow rate reached at outlet 5. The maximum flow rate reached is a predetermined theoretical throughput and generally supplied by the network manager.

Figure 2a shows a retention device 10 according to the invention fixed to a solid support so that the opening 15 of the main net 11 surrounds the outlet 5 of rainwater such as an outlet. As can be seen, the retention device 10 is fixed to the support by its outer net 11, and containing waste 13. Although the opening 15 of the main net 11 is square or rectangular in shape, the latter can be easily made. adapted to the circular rainwater outlet 5 because of the malleability of the rope which constitutes the net. The area of the net inlet opening 15 is larger than the area of the storm water outlet section 5. The retention device according to the invention guarantees the filtering of 100% of the rainwater which passes through it.

The first means of attachment is a set of attachment points. Each fixing point comprising a pair of rigid parts which cooperate together in pairs. The set of first rigid parts of each pair is linked to the net on the outline of its opening 15 and the set of second rigid parts of each pair is fixed on the solid support which surrounds the outlet opening 5 for rainwater. The first rigid pieces are shackles 41, 42, 43 and the second rigid pieces are eyebolts 51, 52, 53. Each shackle 41, 42 and 43 binds the rope of the main net with an eyebolt, 51, 52 and 53 sealed in the solid support. Each coupling of a shackle and an eyebolt 41 and 51 or 42 and 52 or 43 and 53 therefore represents an attachment point. Equivalently, carabiners can be also used instead of shackles. Where the shackles are tied to the rope, the rope is reinforced with splices.

The fixing points are distributed unevenly. The non-uniform distribution of the attachment points of the net aims to distribute the forces evenly along the contour of the opening 15 of the net. Indeed, the weight of the water falling into the net exerts a maximum tensile force on the ropes of the upper face of the net, this tensile force is less important on the ropes of the side faces of the net and is minimal on the ropes. from the underside of the net. The device according to the invention provides three zones on the contour of the opening 15 of the net 11 and on the support for the distribution of the fixing points. These three areas are defined as follows:

- 70% of the fixing points are located on the first zone of the outline of the opening 15 representing between 30 and 40% of the opening 15 and being located on the upper part of the outline, 20% of the fixing points are on the second zone of the outline of the opening 15 representing between 20 and 30% of the perimeter of the opening 15 and located on the middle part of the outline,

- And 10% of the fixing points are located on the third zone of the outline of the opening 15 representing between 30 and 40% of the perimeter of the opening 15 and located on the lower part of the outline.

Within each zone, the fixing points are evenly distributed for ease of installation. The goal being that the shackles or carabiners 41, 42, 43 which are attached to it disconnect at the same time so that there is the least possible damage on the net and on the solid support, this distribution has the advantage of s 'approach this goal. The purpose of this disconnection is to secure the land located upstream by preventing them from flooding. For example, for an outlet 5 with a ^{passage section area of 1 m 2} and a maximum water flow rate at the outlet of between 6 and 8 m ³ / s, the main thread 11 is sized by its dimensions and diameter of its rope to support a weight greater than the force applied by the water on the net corresponds to a weight between 1836 kg and 3264 kg. For a water weight of 1836 kg, each fixing point of the first fixing means will be dimensioned so that the assembly does not withstand more than 1836 kg, ie for example 125 kg per fixing point and for 12 fixing points.

The retention device comprises a second fixing means, illustrated in FIG. 2b, to secure the device and prevent the loss of the net and of the pollutants collected. The second fixing means comprises two lateral fixing points and a rope consisting of two strands 65 and 75 attached to the main net 11 and located at the periphery of its opening 15. The two strands of rope 65 and 75 are substantially of the same length at least. equal to the perimeter of the opening 15 and are attached to the main net in a sliding manner. The first strand 65 and the second strand 75 independently encircle the opening 15 of the main thread 11 and the ends of each strand meet at an attachment point. Each attachment point comprises two rigid parts, a first part 71 sealed in the support such as an eyebolt and a second part 81, such as a shackle or a carabiner, linked to one of the two strands 65 or 75.

When the first fixing means breaks, the part detached from the retention device is offset slightly downstream following the application of hydrodynamic forces and is retained by the second fixing means in order to prevent the main thread 11 and all that. it contains does not move awkwardly on downstream terrain. The two strands of rope 65 and 75 are stretched and therefore are forced to tighten around the opening 15 of the main net 11 to close it and put the net 11 in safety. Then, the main net 11 and all that it contains rests slightly downstream of the storm water outlet in a safe manner because it is retained by the strands of rope 65 and 75 attached respectively to the two fixing points 71, 81 and the opening 15 of the main net 11 is closed by the two strands 65 and 75 of rope thus ensuring the entire retention of solid waste. The retention device is thus secured until the next intervention by the handlers for emptying operations. The two strands of rope 65 and 75 are preferably 14 mm in diameter and can withstand a weight of 2690 kg each.

According to the alternative solution where the net is fixed on a U-shaped fixing frame, a large part of the outline, generally equivalent to three quarters of the outline of the opening of the net is fixed on the frame while the remaining quarter of the outline is fixed on the base on which the legs of the gantry are sealed. The distribution of the fixing points according to the three zones as described above therefore remains valid for this alternative solution.

According to an alternative shown in FIG. 2c, the retention device 10 comprises an overflow hatch 17 made on its upper lateral face. The upper lateral face of the retention device corresponds to the face of the net 11 hooked above the water outlet 5. The overflow hatch 17 is an opening which allows the escape and overflow of part of the waste. This hatch is an additional security in the event of heavy precipitation. The hatch has on its outline fixing means of at least one window 19 of the size of the hatch 17 made of mesh. The mesh size of the net of the window 19 may be different from that of the meshes of the net 11. The net 11 may be associated with windows 19 of different mesh depending on the use. For example for the most common use, the window 19 has a mesh identical to the mesh of the net 11 and is hung on the contour of the hatch 17 by means of a hook-and-loop strip so as to be easily and quickly removable. If the retention device has a second net 21, this also comprises an opening which coincides with the opening of the net 11 corresponding to the overflow hatch 17. The area of the passage section of the overflow hatch 17 being greater than or equal to 30% of the area of the passage section of outlet 5.

The retention device 10 comprises a means for preventing the discharge of waste 13 outside the net 11 illustrated in FIGS. 3 and 4. This means makes it possible, in the case of an aquatic or underwater installation, to prevent the discharge of waste. upstream of the retention device, which may be caused by current disturbances. It also allows waste to be retained in the net when the retention device is detached from its support. The means for preventing the backflow of waste out of the net comprises a third net 31 provided with an inlet opening 35 and an outlet opening 34. The inlet opening 35 of the third net 31 has an at least equivalent surface area. to that of the opening 15 of the main net 11. The net 31 is located so that its inlet opening 35 coincides with the opening 15 of the net and that its outlet opening 34 opens inside of the net 11. The waste transported by the water and entering the net 11 through the opening 15 of the net are symbolized by the arrow 30 in FIG. 4. They pass through the third net 31 entering through its inlet opening 35 and leaving through its outlet opening 34 which opens into the thread 11. The third thread 31 has the shape of a truncated pyramid smaller than that corresponding to the shape of the main thread 11 and oriented in the opposite direction to it. this. The inlet opening 35 of the third thread 31 corresponding to the large base of the small truncated pyramid and the outlet opening 34 corresponding to the large base of the small truncated pyramid has a smaller area than the area of the opening. inlet 35 so that the waste which enters the net 11 by passing through the third net 31 is trapped inside. The area reduction ratio of the inlet and outlet openings 35 and 34 is between 2 and 5.

According to a preferred embodiment of the invention, the third net 31 is mounted on the net 11 removably so that it can be removed or replaced throughout the life cycle of the retention device. The means for making it removable may be a device of hook-and-loop strips.

Each retention device according to the invention installed on site is numbered and equipped with means of identification such as a two-dimensional bar code commonly called a QR code and a user terminal. A set of data is collected at regular time intervals for each retention device installed, thanks to the user terminal. The data collected is transmitted to an online data management and tracking platform. The data collected mainly makes it possible to list the frequency of emptying operations for retention systems, the nature and quantity of waste collected.

In fact, the data collected is listed under three headings. A first section which groups together the identification data of the device, the characterization of the waste it processes, its date of installation and its place of installation. A second section which groups together the structural characteristics of the device and the environment in which it is located. These data mainly include the dimensions of the main net and the type of setting up environment, i.e. whether it is terrestrial, aquatic, underwater, maritime, river, etc. The third section gathers data on the collected waste recorded during the operations of emptying the nets. This may be the nature of the waste collected and its quantity. This third section makes it possible to objectively assess a situation of environmental disorder or to attest to the absence or reduction of the risk of pollution in a defined geographical area.

According to an alternative embodiment of the retention device according to the invention illustrated in Figure 5, the retention device can be integrated into a larger waste collection assembly. The waste collection assembly mainly comprises a primary net 101 arranged as close as possible to the outlet of the storm water network, at least one intermediate net 102 or 103 arranged after the primary net and two retention devices 111, 112 according to the invention arranged side by side after the last intermediate thread in the terminal position. The illustrated embodiment has two intermediate threads 102 and 103. The primary and intermediate threads are juxtaposed one behind the other and each have an inlet opening and an outlet opening, so that the inlet opening of each intermediate thread corresponds with the outlet opening of the preceding thread. The inlet opening of the primary net 101 surrounds the outlet of rainwater not shown in the figure, the outlet opening of the primary net corresponds with the inlet opening of the intermediate net 102 and the outlet opening of the net intermediate 102 corresponds with the entry opening of the intermediate net 103 and the exit opening of the intermediate net 103 corresponds with the entry openings of the main threads of the retention devices 111 and 112. This configuration allows the waste discharged by the exit from crossing the nets and being retained in the nets of the retention devices. When the final nets of waste retention devices 111 and 112 are filled, the large volume of all the nets collects a volume of waste greater than the useful volumes of the nets of retention devices 111 and 112.

In this variant embodiment, the openings of the primary and intermediate threads are maintained by means of intermediate retaining frames 121 and an end retaining frame 122 mounted. sliding on rails 131. The openings of the retention devices 111 and 112 are also held on the end frame 122 which maintains the outlet openings of the last intermediate thread 103. Thanks to the frames mounted to slide on rails, the assembly can pass through 'a deployed position like that shown in Figure 5, where the size of the threads is maximum, to a folded position where the frames are as tight as possible against each other, and vice versa. The folded position has the advantage of reducing the distance between the retention devices and the platform 105 dedicated to crane and lifting and thus facilitates the emptying operations of the retention devices 111 and 112 and possibly of the nets 101, 102 and 103. .

The rails 131 are installed on the flow ramp 106 which preferably has a central channel 116 to channel the water and prevent the waste contained in the nets from being in permanent contact with the water. This characteristic has the advantage of minimizing the share of plastic waste which is reduced to fine particles and has the advantage of avoiding the premature degradation of the equipment that constitutes the whole.

The invention also provides a method of designing the tailor-made retention device described above.

The method of designing the retention device 10 comprises the following steps a) and b): a) Design of a main net 11 comprising an opening 15 intended to be fixed around an outlet 5 of rainwater so that that all the water rejected by the outlet 5 passes through the main net 11, b) Design of a first fixing means of the main net 11 capable of breaking in the event of a tensile force on the main net 11 greater than one limit tensile force corresponding to the weight of the water falling into the main net 11 filled with waste 13 in the case of a maximum water flow rate reached at the rainwater outlet 5. The main net 11 of the retention device 10 according to the invention is custom designed from a standard model and taking into account the contextual and environmental constraints of the site where it will be installed. Consequently, step a) of the process for designing the made-to-measure retention device comprises the following steps noted a1) to a9): a1) Acquisition of dimensional data for each device, relating to the installation site of the device, a2) Estimation of the maximum tolerated useful volume corresponding to the maximum volume of waste recoverable on the site according to the constraints of extraction of the device to empty it, a3) Estimation of the filling rate of the main net 11 according to the positioning of the device, a4) Design a main rule 11 from a model rule in the shape of a truncated pyramid with a square or rectangular base, the small base of the truncated pyramid corresponding to the opening of the thread, to which the height, the length of the edges of the small base and the angles of the side surfaces with the base, to the dimensional data acquired in step a), a5) Calculation of the total area of the main thread 11, a6) Calculation of the vo total volume of the main thread 11, a7) Calculation of the practical useful volume corresponding to the product of the filling rate estimated in step c) by the total volume of the main thread (11) calculated in step f), a8) Comparison of practical useful volume obtained in step a7) with the maximum tolerated useful volume estimated in step a2), a9) Determination of the main threads 11 valid for a particular installation site among the main threads 11 obtained according to steps a1) to a8), if the maximum tolerated usable volume is greater than the practical usable volume.

For step a1), the dimensional data take into account the diameter of the rainwater outlet 5, the dimensional constraints in width and length downstream of the outlet.

Step a2) consists in estimating the maximum tolerated volume of the main thread. In fact, depending on the accessibility of the site, the dimensions of the lifting device that can be approached from the place of installation of the device will be limited or else it it will not be possible to approach a lifting device. These constraints are taken into account to estimate the maximum tolerated volume of the main thread.

Likewise, step a3) consists in estimating the percentage of the volume of the net that can actually be filled with waste. Indeed, depending on the inclination of the flow ramp on which the main net rests, the filling rate is different. For example, the filling rate is 70% when the flow ramp is horizontal and in the extension of outlet 5. The filling rate will be 100% when the flow ramp is vertical. It is estimated that in the case of a horizontal ramp, when the net reaches 70% fill, the waste carried by the water begins to fill the pipe upstream of outlet 5.

From the dimensional data acquired in step a1), the geometric characteristics of the main thread 11 are determined from a standard pattern of the thread in the shape of a truncated pyramid according to step a4). The truncated pyramid shape is therefore common to the main thread of all retention devices designed according to the method of the invention. From the geometric characteristics of the net we can calculate the area of the net walls as well as its total area and the theoretical volume of the net according to the formula for the volume of a truncated pyramid. These calculations are carried out in steps a5) and a6) of the process.

The practical useful volume calculated in step a7) is a theoretical volume. It is equal to the product of the total volume of the net times the fill rate of the net.

The practical useful volume obtained in step a7) is compared with the maximum tolerated useful volume estimated in step a2). The nets obtained by steps a1) to a8) of the process are considered adequate for a particular installation site when the maximum tolerated useful volume is greater than the practical useful volume.

The first means of fixing the net is dimensioned according to the resistance of the net and the resistance of the fixing points and also according to the dynamic stresses which are a function of the maximum water flow which is theoretically possible to achieve.

Step b) of the retention device design method comprises the following steps denoted b1) to b8): b1) Acquisition of characteristic data of the rope used to manufacture the main net 11, b2) Acquisition of characteristic data of the rainwater outlet 5, such as the area of the outlet passage section and the maximum water flow, b3 ) Acquisition of characteristic data of the first fixing means such as the number of fixing points and their unit breaking strength, b4) Calculation of the maximum tensile force admissible by the first fixing means before breaking according to the data acquired at step b3), b5) Calculation of the force applied to the main thread 11 in the event of maximum water flow reached at the rainwater outlet 5, b6) Calculation of the maximum tensile force admissible by the main thread 11 before rupture as a function of the data acquired in step b1) and of the number of fixing points, b7) Comparison of the values calculated in steps b4), b5), and b6), b8) Validation of the first fixing means for r the main threads 11 whose values calculated in steps b4), b5), and b6) verify the following relationship: the force applied to the main thread 11 in the event of maximum water flow is greater than the maximum admissible tensile force by the first fixing means and less than the maximum tensile force admissible by the main thread 11.

For step b1), the characteristic data of the rope used to manufacture the main net 11 are those intrinsic to the rope and are provided by the manufacturer, namely the diameter of the rope and the gross unit breaking strength. Rope characteristics also include characteristics when the rope is tied. Each knot and each splice loses resistance to the rope because they induce friction. In addition, a safety coefficient is provided and between 7 and 14, this coefficient is linked to the environmental uncertainties specific to the aquatic environment. For step b2), the dimensions of the rainwater outlet are recorded on the site installation and the maximum water flow is taken from previous and usual readings.

The characteristic data of the fixing points acquired in step b3) are inherent to the material used, they are therefore provided by the manufacturer, it is the unit breaking strength of the first rigid parts 41, 42, 43 linked to the net such as shackles or carabiners.

The calculation made in step b4) gives the maximum force admissible by all the attachment points before they break. This result is essential because it represents the tensile threshold that can be supported by the first fixing means.

The calculation of the force applied to the net in the event of maximum water flow carried out in step b5) goes through the calculations of maximum speed and of pressure applied in the event of maximum flow and is carried out from Bernoulli's theorem . The calculation of the maximum admissible tensile force by the net carried out in step b6) before breaking takes into account the number of attachment points because the strands of linear net rope directly linked to an attachment point have a significant impact on the general resistance of the net while the other strands, which are not directly connected to an attachment point, participate in the resistance of the net in a negligible way.

According to step b7) the results of the calculations obtained in steps b4, b5 and b6 are compared because, on the one hand, the maximum tensile force admissible by the first fixing means must be less than the force applied to the thread in case of maximum water flow so that the first fixing means can break by disconnecting the shackles or carabiners in the event of unfavorable weather conditions and on the other hand, the maximum admissible tensile force on the net must be greater than the force applied to the net in case of maximum water flow, so that the net maintains its integrity and does not release waste into nature. The maximum tensile force admissible by the second means of fixing the net is dimensioned to always be greater than the force applied to the net in the event of maximum water flow. The second means of attachment is oversized to avoid breaking in any weather condition.

Claims

1. Retention device (10) for waste (13) comprising a main net (11) and at least one fixing means suitable for fixing an opening (15) of said main net on a solid support, said opening surrounding an outlet (5). ) a storm water network so that all the water discharged from said outlet (5) passes through said main net, characterized in that the resistance of the main net is such that it can withstand the force of limit traction corresponding to the weight of the water falling into the main net (11) filled with waste (13) in the event of a maximum water flow rate reached at the outlet (5), the resistance of at least one means of binding being dimensioned as a function of this limit tensile force and the resistance of said main thread to be less than this limit tensile force so that the retention device (10) detaches from its support when this tensile force is reached and avoid thus the obstruction of the exit (5) rainwater and flooding of the parts located upstream of the retention device and in that the net (11) has a flared shape so that between its opening (15) through which the water loaded with waste enters and the face of the bottom (14) of the net, the passage surface inside the net also referred to as the passage section, increases by a ratio of between 1.5 and 2.5.

2. Device according to claim 1, wherein the main thread (11) has the shape of a truncated pyramid with a square or rectangular base, the opening (15) of the thread corresponding to the small base of the truncated pyramid.

3. Device according to claim 1 or 2, comprising a second thread (21) of identical shape to the main thread (11), the characteristic dimensions of which are those of said main thread increased by 3% to 10% and preferably by 5% and the mesh size of which is smaller than the mesh size of said main net.

4. Device according to claim 1, 2 or 3, wherein the first fixing means of the main net (11) on the support is a set of points of fixing (41, 51, 42, 52, 43, 53), each fixing point comprising a first rigid part such as a shackle (41, 42, 43) linked to the main thread (11) on the contour of its opening ( 15) and a second rigid piece such as an eyebolt (51, 52, 53) sealed in the solid support, the fixing points being distributed around the opening (15) of the main thread (11) in a non uniform in three zones, depending on the distribution of the tensile forces acting on the fixing points.

5. Device according to claim 4, wherein said three areas on the outline of the opening (15) of the net (11) and on the support for the distribution of the fixing points are defined as follows:

- 70% of the fixing points are located on the first zone of the contour of the opening (15) representing between 30 and 40% of the perimeter of the opening (15) and located on the upper part of the contour, - 20% attachment points are located on the second area of the contour of the opening (15) representing between 20 and 30% of the perimeter of the opening (15) and located on the middle part of the contour, 10% of the attachment points are located on the third zone of the contour of the opening (15) representing between 30 and 40% of the opening (15) and located on the lower part of the contour.

6. Device according to one of claims 1 to 5, comprising a second fixing means composed of two lateral fixing points (71, 81) and a rope consisting of two strands (65, 75) attached to the main net ( 11) and located at the periphery of the opening (15), the two strands of rope of substantially the same length, are attached to said main net in a sliding manner, the first strand (65) and the second strand (75) independently encircle the from each other the opening (15) of said main net, each attachment point comprising a first rigid part (71) sealed in the wall such as an eyebolt and a second rigid part (81), such as a shackle or a snap hook, linked to one of the two strands (65) or (75).

7. Device according to one of claims 1 to 6, comprising means for preventing the waste (13) contained in the retention device (10) from backing out of the main net (11).

8. Device according to claim 7, wherein the means for preventing the waste (13) contained in the retention device from pushing back outside the net comprises a third net (31) in the form of a truncated pyramid comprising two openings, an inlet opening (35) of area at least equivalent to that of the opening (15) of the main thread (11), the thread (31) being located so that its inlet opening ( 35) coincides with the opening (15) of the net and that its outlet opening (34) opens inside the net (11).

9. Device according to one of claims 1 to 8, comprising an overflow hatch (17) produced on the upper side face of the retention device, in the form of an opening which allows the escape and overflow of a part. waste, said hatch has on its outline fixing means of at least one window (19) removable and made of mesh, the area of the passage section of the overflow hatch (17) being greater than or equal to 30% the area of the passage section of the outlet (5).

10. Device according to one of claims 1 to 9, of which a set of data is collected at regular time intervals by means of identification means such as a two-dimensional bar code and a user terminal, the data collected. being transmitted to a data management and online monitoring platform, mainly make it possible to list the frequency of emptying operations of the retention devices (10), the nature and quantity of waste (13) collected.

11. Assembly for collecting waste at the outlet of the rainwater comprising a primary net (101) arranged as close as possible to the outlet of the rainwater and at least one intermediate net (102, 103) arranged after the net, said primary nets and intermediates are juxtaposed one behind the other and each have an inlet opening and an outlet opening, so in that the inlet opening of each intermediate thread corresponds with the outlet opening of the thread preceding it, characterized in that the assembly comprises two retention devices (111, 112) according to one of claims 1 to 10 , the outlet opening of the intermediate thread (103) corresponding with the inlet openings of the threads of the retention devices (111, 112).

12. The assembly of claim 11, wherein the openings of the primary and intermediate threads are maintained by means of intermediate retaining frames (121) and an end retaining frame (122) slidably mounted on rails (131), said frame of terminal retention also maintaining the openings of the threads of the retention devices (111, 112), the assembly being able to pass from a deployed position where the size of the threads is maximum, to a folded position where the frames (121, 122) are tightened as much as possible against each other, and vice versa.

13. Assembly according to one of claims 11 or 12, having a platform (105) dedicated to crane and lifting located near the outlet of the storm water network, and a flow ramp (106) located in front of the outlet. water, comprising a central channel (116), said platform (105) allowing, when the assembly is in the folded position, to facilitate the emptying operations of the retention devices (111, 112) and of the nets (101, 102, 103).

14. A method of designing a custom-made retention device (10) according to one of claims 1 to 10, comprising the following steps: a) Design of a main thread (11) comprising an opening (15) intended for come to be fixed around an outlet (5) of the rainwater network so that all the water rejected by the outlet (5) passes through the main net (11), b) Design of a first means for fixing the main net (11) capable of breaking in the event of a tensile force on the main net (11) greater than a limit tensile force corresponding to the weight of the water falling into the main net (11) filled with waste (13) in the case of a maximum water flow reached at the outlet (5) of the storm water network.

15. A method of designing a tailor-made retention device (10) according to claim 14, wherein step a) comprises the following steps: a1) Acquisition of dimensional data for each device, relating to the installation site of the device. device, a2) Estimation of the maximum tolerated useful volume corresponding to the maximum volume of waste recoverable on the site as a function of the extraction constraints of the device to empty it, a3) Estimation of the filling rate of the main net (11) depending on the positioning of the device, a4) Design of a main thread (11) made to measure from a model thread in the shape of a truncated pyramid with a square or rectangular base, the small base of the truncated pyramid corresponding to the opening of the thread, to which we adapt the height, the length of the edges of the small base and the angles of the side surfaces with the base, to the dimensional data acquired during step a), a5) Calculation of the total surface of the thread main (11), a6) Calculation of the total volume of the main net (11), a7) Calculation of the practical useful volume corresponding to the product of the filling rate estimated in step c) by the total volume of the main net (11) calculated in step f), a8) Comparison of the practical useful volume obtained in step a7) with the maximum tolerated useful volume estimated in step a2), a9) main threads (11) valid for a particular installation site among the main threads (11) obtained according to steps a1) to a8), if the maximum tolerated useful volume is greater than the practical useful volume.

16. A method of designing a custom-made retention device (10) according to claim 14 or 15, wherein step b) comprises the following steps: b1) Acquisition of characteristic data of the rope used to manufacture the main net ( 11), b2) Acquisition of characteristic data of the rainwater outlet (5), such as the area of the outlet passage section and the maximum water flow, b3) Acquisition of characteristic data of the first fixing means such as the number of fixing points and their unit breaking strength, b4) Calculation of the maximum tensile force admissible by the first fixing means before rupture according to the data acquired in step b3), b5) Calculation of the force applied to the main thread (11) in the event of maximum water flow reached at the outlet (5) of the storm water network, b6) Calculation of the maximum tensile force admissible by the main thread (21) before breaking according to the data acquired in step b1) and the number of fixing points, b7) Comparison of the values calculated in steps b4), b5), and b6), b8) Validation of the first fixing means for the main threads (11) including the values calculated in steps b4), b5), and b6) vé rify the following relationship: the force applied to the main thread (11) in the event of maximum water flow is greater than the maximum tensile force admissible by the first fixing means and lower than the maximum tensile force admissible by the thread main (11).