WO1986001552A1 - Ground drainage method, system for implementing such method and application of the method - Google Patents

Abstract

Ground drainage method comprising the connection of a perforated conduit (10), in intimate contact with the porous underground (5) and winding up and down in a same plane parallel to the ground, with a pumping station (101) capable of operating in a suction mode to create a vacuum which accelerates the drainage of excess water, and in a discharge mode for injecting water, fertilizer, reheated water therein ... which come up by capillarity to the tilth (3). The invention applies to the drainage and irrigation particularly of sport grounds, recreational lawns, market gardenings, greenhouses, as well as to the regulation of more or less immersed cultivation soils, such as rice fields.

Description

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LAND DRAINAGE METHOD - SYSTEM IMPLEMENTING SUCH A METHOD AND APPLICATION OF THE METHOD

The invention relates to a system for draining a ground, in particular sports grounds, sports grounds for tennis, sports halls or green spaces in general as well as the treatment of particular grounds where the cultivation is done in more or less grounds. less humid such as rice fields for example. It also relates to any system implementing such a method, as well as the applications arising therefrom.

The classic technique consists in making flow trenches crisscrossing the surface of the land to be drained, in which the earth is replaced by a material intended to ensure the flow of water from the topsoil to the appropriate underlying gravel layer. Another known technique consists in forcing the filling material into the earth by force to ensure the same function.

There is for example in French patent 2,244,356 a basic drainage system produced using drains housed in filter media, and surface drainage produced using draining trenches connecting the soil surface to the filter media that 'they cut over part of their height. To improve the efficiency of such a structure, the drains and the corresponding filter media are arranged on an ear relative to the longitudinal axis of the ground, the angle which their direction makes with this axis being for example 60 °.

. Another technique, described in particular in American patent 3,908,385, calls for the establishment of a porous layer of vermiculite over the entire surface of the soil to be drained, and of lateral channels connected to a main pipe, itself in communication or not with a suction pump. The lateral channels have slots and are arranged at a determined height from the surface. They join a main pipe located below (at a depth therefore greater than that of the lateral channels) so that the water flows by gravity into the main pipe. The pump helps with this evacuation. Here again, gravity plays its role.

All these techniques have the disadvantage of requiring the existence

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a slope which, if it is not natural, must be created artificially, which most often poses a problem whose solution is extremely expensive. The flow then takes place by gravity towards one or more collecting networks which make it possible to drain the water thus collected towards a general drainage network. Another drawback of these systems is located in the sedimentation deposits which very quickly obstruct the collector network, which obviously affects, in the short term, the efficiency of the system.

Conversely, when drought sets in and irrigation and / or humidification of the soil generally have to be carried out, all kinds of watering techniques are conventionally used, which risk creating thermal shocks at the level of the lawn and to be harmful by the often brutal projection of the sprinkling on the foliage.

In the case of the technique described by the aforementioned American patent, it is certainly possible, by reversing the direction of operation of the pump, to carry out by the same pipe circuit, irrigation. Unfortunately, if gravity is used for the evacuation of water, eEe is opposed to its rise and problems of homogeneity and humidification arise. There are also risks of localized sedimentation that are difficult to avoid.

The present invention aims to overcome these drawbacks and relates to a drainage process capable of performing this function without the need to use any slope, for the evacuation of water, this process does not rely on a drainage water drainage by gravity. Such a process has the enormous advantage of making it possible to fetch the water to be evacuated, at a very great distance, or, conversely, to distribute it on demand as far as necessary, and this in a homogeneous manner over the entire surface. to irrigate.

It also relates to a drainage system implementing such a method which, in addition to its drainage function, makes it possible to ensure controlled irrigation of the subirrigation type which can even be automatic without the need for recourse to drainage systems. surface watering with all the inconvenience this entails.

One of the advantages of the invention is therefore, on the one hand, to control water drainage and, on the other hand, irrigation by means which are effective and simple to implement, and which limit work as much as possible.

maintenance.

Another advantage consists in avoiding, in all points, all risks of untimely sedimentation.

The present invention relates more precisely to a land drainage method comprising a network of trenches connecting the topsoil to the porous subsoil; it is characterized in that a network of drains, in the form of a perforated pipe in intimate connection with this porous basement, • covering without any solution of continuity all the surface concerned and contained in a single plane, is connected to a pumping station capable of putting this pipe under vacuum to suck, or under pressure to push back.

The invention will be better understood using the explanations which follow and the attached figures, among which:

- Figure 1 is a schematic illustration of the method and the drainage system of a land, according to the invention; - Figure 2 is a schematic illustration of the drainage system according to Figure 1, the operation of which is opposite to the previous one, that is to say that it operates in an irrigation system, instead of operating in a drainage system;

- Figure 3 illustrates an important detail of a system according to the invention; - Figure 4 schematically illustrates a control operation simplifying maintenance procedures, achievable through the implementation of a system according to the invention;

- Figure 5 shows schematically, in section, an installation implementing a system according to the invention; - Figure 6 schematically illustrates an application of the method and the system according to the invention.

For the sake of clarity, the same elements are given the same references in all the figures.

Figure 1 schematically illustrates, seen in section, a drainage method according to the invention. Initially, the digging is carried out, according to a determined configuration, of a trench 1, which is filled with a porous material such as gravel, responsible for collecting the excess water 70 from the surface 2, from the ground. covered with topsoil 3, and which carries, for example, a lawn 33 to bring it towards the porous layer 5, underlying. One can, to achieve this trench, proceed in a conventional manner. However, it is recommended to use a soil digging machine, - 4 -

developed by the plaintiff and which is the subject of a French patent application filed under No. 83 08760, on May 20, 1983. It is a machine whose essential characteristic resides in the fact that the organ excavator of the machine turns clockwise, so that the earth is recovered at the front of this member if we look at the direction of advance of the machine. The earth is then transferred to an endless belt, with a view to its evacuation, the direction of travel of which goes from the front of the machine towards the rear of the latter. Such an architecture makes it possible to position a tank containing the filling product so that, whatever its load, the center of gravity of the machine remains practically constant.

A plurality of such drainage trenches 1 being produced, a drain 10, which is in the form of a perforated pipe is brought into intimate contact with the porous layer 5, to collect the excess water. According to an extremely important characteristic of the invention, this drain 10 is in the form of a perforated pipe whose physical characteristics are such that it supports a vacuum.

As can be seen more clearly in FIG. 6 which is an illustration of an application of the invention, this drain (10) winds in a determined plane over the entire surface to be drained concerned. It has no solution of continuity. This pipe is, according to another characteristic of the invention, connected to a pumping station, not shown in Figure 1, but which will be illustrated later. During the vacuuming operation, the water will undergo a forced circulation all along the pipe (10) towards the evacuation without having to be subjected to any action of gravity. The slope, under these conditions, is no longer necessary.

Thus, depending on the size of the vacuum created, the pumping of the water will be more or less rapid and its evacuation will depend on it. It is therefore possible, under these conditions, to control the operating conditions of the vacuum pump, as a function of the drainage parameters that have been carefully programmed beforehand.

This is an extremely important function of the drain 10, the role of which is no longer only to convey the drainage water to the evacuation but to accelerate, in a controlled manner, this evacuation thanks to the effect of vacuum created within this drain 10. Thus, in the event that sedimentation plugs are formed, these would be automatically

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disaggregated and evacuated.

Such an operation will preferably take place in the event of excess water, that is to say outside the drought seasons, when the supply of rainwater is maximum. Conversely and according to another important characteristic of the invention, the reversal of the phenomenon of water circulation created by vacuum pumping can be achieved when the drought is felt. Instead of sucking the water through the drain 10, if the degree of humidification of the topsoil proves essential to safeguard the vitality of the plantations, the pumping unit is still operated, but instead of operating it in suction, it is then operated in discharge.

As shown in FIG. 2, a quantity of controlled water is then injected into the drain 10 which runs through the circuit formed by the drain 10. Thus, this injected water progresses by capillarity through the trenches 1 and towards the topsoil 3 qu 'it irrigates evenly. It suffices to optimize the number and distribution of these trenches to obtain a level of humidification water at planted ground 71.

Another application also consists in including in this irrigation water, fertilizers, in whatever form, which, through the subsoil will progress towards the surface and feed the roots of plants, lawns or trees which will have then tend to be attracted in depth. We will thus be faced with a perfectly controllable irrigation and fertilization process.

In the case of Figure 1, the water circulation will be according to arrow FI; on the other hand, in the case of FIG. 2, this circulation will be in the direction of the arrow F2. In a nonlimiting example, the diameter of the drain 10 could be close to φ = 50 mm. The water circulating inside the drains 10 penetrates and thus progresses at a constant speed towards the trench holes 1 (which, in this phase operate as drippers), the water pressure is thus distributed uniformly from the start to 'at the end of the drain 1. There follows a deep wetting of the earth, without loss of water, by evacuation or drainage. The roots of the grass are attracted deep which increases their resistance to tearing and allows them to draw mineral salts in depth. In addition, the leaching of fertilizers, especially nitrogen, is avoided.

It should be noted, as has already been said previously, according to

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an essential characteristic of the invention, a single pipe (10) is positioned in a determined plane, relative to the surface of the ground. It follows that the drainage of water as well as humidification or irrigation, or even when necessary, with water loaded with fertilizer, will be carried out in a homogeneous manner without any intervention of gravity. for drainage or elsewhere the need to overcome this gravity for irrigation.

In certain applications, the water injected into the circuit will be heated and, in turn, will ensure that the soil stays frost-free, which is not without interest, especially when the climatic conditions are detrimental to the proper functioning of the sports facilities. in particular, concerned.

For the proper functioning of the assembly, both in the suction phase and in the irrigation phase, as shown in FIG. 3, maintenance outlets 30 are provided on the drainage circuit, at regular intervals . Visual or automatic checks are, under these conditions, entirely possible and do not pose any operating problem. These inspection manholes are spaced, for example, 150 m from each other.

To facilitate checks of a system according to the invention, as shown in FIG. 4, the user can introduce inside the drain 10, which is none other than the perforated pipe supporting a vacuum, or under pressure a control member 60, capable of visualizing what is happening inside this drain 10. It may be, in particular, an endoscope of the fiber optic type currently available on the market. In the example described, this is a football field where a player 61 plays with the ball 63, while the employee checks with an endoscope 60.

Figures 5 and 6 show, respectively, seen in section and in plan an application of the present invention. This is by way of nonlimiting example of a sports field and more particularly of a play area 111 surrounded by a track 120. Such a field comprises the combination of a network of trenches 1, furrowed in the transverse direction by a drain 10, in a given plane and parallel to the ground surface, leading to a connection connected to a pumping group 101, capable at the same time, of ensuring a suction function (evacuation) or discharge (pressurized water). FIG. 6 shows a football field 111, with its classic boundaries of the playing areas (goal 110, and midfielder, as well

than a track 120). In section appears in more detail the pumping station 101, comprising its vacuum and discharge pump 80, and an evacuation outlet 90, which during a drought phase becomes a source of water or fertilizer supply. or water / fertilizer mixture. As has already been said previously, such a method, its implementation system and its applications have numerous advantages.

They lead, in fact, to a water saving of 30 to 50% and considerably facilitate maintenance work, while allowing automatic programming, both of drainage and of irrigation. Indeed, this system essentially consists of a buried network maintained under permanent vacuum which ensures the transport of drainage water. The vacuum system receives the water and can easily discharge it into a main sewer. It can also discharge it into a reservoir from which we can draw for a possible irrigation phase. Moreover, one of the applications of the invention is in the technique of rice field exploitation. It is indeed possible, thanks to the implementation of the present invention to pump water from a site, at a certain level, to lead it to another level and vice versa, which, in the case rice cultivation can significantly increase the yield. A simple system of valves (manual or electric) allows the loading of the flow trenches which then become supply trenches by capillarity.

As an example, if we return to an example previously described, a traditional sports field which, in the known art, undergoes watering of 70 cubic meters of water per week, sees half of this water, or 35 cubic meters directly absorbed by the drainage. On the other hand, the present invention makes it possible to spend only the 35 cubic meters necessary without practically any loss, the level being kept automatically constant. Such a system is, moreover, independent of the concentration of rain.

Finally, many sports fields are currently built on landfills, which, over time, has the effect of causing subsidence in the traditional drainage system, preventing, therefore, the evacuation by gravity of drainage water and This makes the play area impracticable. This drawback disappears with the implementation of the method and of the system according to the invention.

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As has been said previously, the present invention applies to the drainage and irrigation of any green space, for pleasure and for sport, - vegetable crops, greenhouses, without forgetting all the applications relating to crops. performing in humid environments but, the humidification rate of which must be strictly controlled.

Claims

1) Land drainage method comprising a network of trenches (1) connecting the layer of topsoil (3) to the porous subsoil (5), characterized in that a network of drains in the form of a perforated pipe (10), with no continuity solution and winding in the same plane parallel to the ground surface, in intimate connection with this porous basement (5) is connected to a pumping station (101) capable of operating in suction or in repression, and this, in the absence of any effect of gravity. 2) Method according to claim 1, characterized in that water is injected into the perforated pipe (10) and rises through the trenches (1) and uniformly irrigates the layer of topsoil (3) thus ensuring its humidification ( 71). 3) Method according to claims 1 and 2, characterized in that fertilizer is injected into the network of drains (10) and rises by capilarite through the trenches (1) towards the layer of topsoil (2) that it fertilizes. 4) Method according to one of the preceding claims, characterized in that the heated water is injected by means of the pumping station (101) through the pipe (10). 5) Drainage and irrigation system implementing a method according to one of the preceding claims, characterized in that the perforated pipe (10) is connected to a pumping station (101) equipped with a pump (80 ) capable of operating in suction and discharge and connected to an outlet (90) having two functions: the first evacuation, the second supply. 6) System according to claim 5, characterized in that maintenance outlets (30) are provided at regular intervals. 7) System according to claim 6, characterized in that control means (60) capable of viewing what is happening inside the perforated pipe network are introduced into the service outlets (30). 8) Application of the method and the irrigation system according to one of the preceding claims, characterized in that the ground thus treated is a sports ground, comprising a playground (111) and a track (120). 9) Application according to claim 8, characterized in that the ground thus treated is a green space for pleasure.

- 10 - 10) Application according to claim 8, characterized in that the water pumped through the pipe (10) and the pumping station (101) is collected in a tank and can be used again.