ARRANGMENT FOR ADJUSTING MOISTURE CONTENT OF THE SOIL OF A SPORTS FIELD

Abstract

Arrangement for adjusting the soil moisture of a sports field, the structure (S) of which contains a field surface (P), a tread layer (9) below the field surface (P), and a support layer (T) formed below the tread layer (9), and the tread layer (9) is separated from the support layer (T) by a separating layer (V), a network of drainage pipes (6) is arranged in the support layer (T) and connected to a pool (M), and the support layer (T) is lying on a waterproof film (4). The basin (M) is provided with a filling valve (26) and a sluice opening (13) the lower flow level (A) of the latter is arranged below the upper level of lower crushed stone layer (A).

Claims

1. An arrangement for adjusting the soil moisture of a sports field, the structure (S) of which contains a field surface (P), a tread layer (9) below the field surface (P), and a support layer (T) formed below the tread layer (9), and the tread layer (9) is separated from the support layer (T) by a separating layer (V), a network of drainage pipes (6) is arranged in the support layer (T) and connected to a pool (M), and the support layer (T) is lying on a waterproof film (4), wherein the separating layer (V) is formed of a geogrid (8), and the support layer (T) contains an upper crushed stone layer (2b) and a coarser, lower crushed stone layer (2a) connected to it from below, and between the upper crushed stone layer (2b) and the geogrid (8) a geotextile (8a) is arranged, and the film (4) are folded over the edges of the field surface (P) above the field surface (P), and between the geotextile (8a) and the foil (4) a geogrid strip (22) coated with a geotextile material is arranged, and the geotextile material is in contact with the geotextile (8a) plate, and the basin (M) is provided with a filling valve (26) and a sluice opening (13) the lower flow level (A) of the latter is arranged below the upper level of lower crushed stone layer (A).

2. The arrangement according to claim 1, wherein a drain pipe (6) is connected to a collecting pipe (7) connecting the basin (M) and the drain pipe (6).

3. The arrangement according to claim 2, wherein the lowest level of the collecting pipe (7) is arranged below the lower flow level (A).

4. The arrangement according to claim 3, wherein the upper crushed stone layer (2b) is made of crushed stone with a grain size of 4 to 11 mm.

5. The arrangement according to claim 4, wherein the lower crushed stone layer (2a) is made of crushed stone with a grain size of 11 to 22 mm.

6. The arrangement according to claim 5, wherein the basin (M) is divided into a smaller first chamber (11) and a larger second chamber (12), and the chambers (11, 12) are connected by means of the sluice opening (13), and the collecting pipe (7) is connected to the first chamber (11).

7. The arrangement according to claim 6, wherein the second chamber (12) is provided with an overflow opening (23) with a lower flow level (B) arranged at a level lower than the lower flow level (A) of the sluice opening (13).

8. The arrangement according to claim 7, wherein the filling valve (26) is arranged to open into the second chamber (12), and the two chambers (11, 12) are connected by means of a pipe (14a) connected to the submersible pump (14) located in the second chamber (12), and a water level sensor (16) is arranged in the first chamber (11).

9. The arrangement according to claim 8, wherein the pool (M) is equipped with an automatic control means (15) to which a remote-controlled sluice (Z) for operating the sluice opening (13), the submersible pump (14), the water level sensor (16) and the remote-controlled filling valve (26) are connected.

10. The arrangement according to claim 1, wherein the field surface (P) is the surface of the tread layer (9).

11. The arrangement according to claim 1, wherein the field surface (P) is a lawn mat comprising lawn species planted in a layer of soil arranged on the tread layer (9).

12. The arrangement according to claim 1, wherein the field surface (P) is a synthetic grass layer arranged on the tread layer (9).

Description

[0023] The invention will now be described in more details with reference to the accompanying drawings. In the drawings

[0024] FIG. 1 shows the layers arranged below the field surface of the arrangement according to the invention with basement pipes,

[0025] FIG. 1a. shows an enlarged view of a geotextile strip arranged at the edge of the field surface,

[0026] FIG. 2 shows a detail of a separating grid,

[0027] FIG. 3 shows the arrangement of drainage pipes and collecting pipes in the field structure in top view,

[0028] FIGS. 4a and 4b. shows a cross-section of the installation of drainage pipes and collecting pipes, and

[0029] FIG. 5. a cross section of a two-chamber control basin.

[0030] FIG. 1 shows a vertical section of the layered field structure S with basement pipes arranged below the field surface P of the sports field arrangement according to the invention. In a preferred embodiment suitable e.g. for performing horse racing as shown, there is a tread layer 9 below the field surface, made of quartz sand and textile chips, which forms the field surface P itself, and which has a thickness preferably between 10 and 15 cm, and is wetted in a capillary way up to the field surface P. In another preferred embodiment, which is not shown in the figure, and is suitable e.g. for performing ball games, the field surface P is a turf arranged on the tread layer 9, the material of which is made e.g. of lawns planted in a layer of soil known from the art, and which is capable of discharging its moisture content into the tread layer 9 and, if appropriate, for absorbing moisture therefrom. In a further preferred embodiment, the field surface P can even be a turf mat made of synthetic fibers arranged on the tread layer 9, which is also well known in the art and is capable of absorbing and releasing moisture. Below the tread layer 9, a grid 8 is placed as a separating layer V, which e.g. a simple grid made of high-density polyethylene (HDPE), the details of which are shown in FIG. 2. The preferably about 1 cm thick grid 8 has a high liquid permeability, which allows a large amount of water to pass quickly through the grid 8 even when its pressure is low. Determining the size of the grid holes 81 of the grid 8 shown in FIG. 2 by a series of experiments, it was found that the grid hole 81 is preferably rectangular, with a hole size of preferably 10-16×10-16 mm, most preferably 12×12 mm.

[0031] Referring to FIG. 1, a geotextile plate 8a made of polypropylene (PP) preferably plastic to the grid 8 is located below the grid 8, but it can be made of other, plastic weldable, fabric-like, non putrefiable material. The geotextile plate 8a also permeates the liquid, but not the sand grains of the tread layer 9 located in the holes of the grid 8. The upper tread layer 9 rests stably and friction tightly on a separating element consisting of 8 grid and 8a geotextile having a liquid permeability of about 221/s.Math.m.sup.2, ensuring the stability of the field surface P.

[0032] In order to increase resilience of the field surface P, in a preferred embodiment, a 25-30 mm thick layer of crushed rubber grit (not shown) may be placed under the geotextile plate 8a to spare the feet of athletes/horses and thus protecting their health. Laying the separating element consisting of the grid 8 and the geotextile 8a is quick and easy. Thus, the bonding task of a conventional cassette separator does not occur.

[0033] An upper crushed stone layer 2b as a support layer T is arranged under the geotextile plate 8a. The stones forming the layer 2b preferably have a grain size of 4-11 mm. The layer 2b is spread on a further, coarser lower crushed stone layer 2a, the grain size of which in the embodiment shown is between 10 and 22 mm. Forming the grid 8 and the geotextile plate 8a according to the invention, an even and flexible load distribution acting on the crushed stone layer 2a, 2b can be achieved, while effectively preventing the horizontal slippage of the quartz sand forming the layer 9 during training, competitions and track maintenance.

[0034] Below the stone layer 2a, a foil 4 of high density polyethylene (HDPE) fibers is arranged on a 20-30 mm thick complanating sand layer H spread on a suitably compacted subsoil 1. The tensile strength and flexibility of the foil 4 provide flexible support for the layers forming the field structure, and its watertight surface is resistant to damages occurring during the mechanical spreading and compaction of the crushed stone layers 2a, 2b. The foil 4 and the grid 8 and the geotextile plate 8a are folded on the edges Pp of the field surface P as shown in FIG. 1 in order to prevent water from lateral leaking out of the track structure S. The folded foil 4, the grid 8 and the geotextile plate 8a it can rest e.g. on a side wall 18 formed along the edge Pp of the field surface P. The material of the side wall 18 is preferably monolithic concrete, to which a railing 19 and a curb 21 can be connected. Due to the fact that the vertical movement of water in the pool-like field structure S is very fast, it is necessary to allow the air in the field structure S to escape when the water level is raised, otherwise the buckling of the tread layer 9 must be expected. To prevent this, as shown enlarged in FIG. 1a, a geotextile strip 22 coated with a geotextile material is arranged between the grid 8 folded on the side wall 18 and the folded foil 4 so that the geotextile material is in contact with the geotextile plate 8a. This creates a thin gap between the curb 21 and the layer 9, which runs along the entire edge Pp of the field surface P and through which the air can flow freely between the environment and the track structure S.

[0035] The described field structure S forms a volume watertightly isolated from the surrounding soil, from which the drainage pipes 6, preferably 80-120 mm in diameter, laid on the foil 4, and the connected larger 160-315 mm in diameter collecting pipes 7 connected to them and laid within the layer of sand H and passing through a cover collar G, lead to a basin M arranged outside the field structure S, as shown in FIG. 3 in a top view.

[0036] As can be seen in FIGS. 4a and 4b, only the collecting pipes 7 (FIG. 4b) are embedded in the ground 1, so that the thickness of the part of the field structure S above the collecting pipes 7 is preferably only 25-30 cm (FIG. 4a), in contrast with a layer thickness of 70-80 cm of prior art solutions, which allows to save on both the material and the work involved in installation.

[0037] Drain pipes 6 are connected to the 7 collecting pipes directly, through a hole drilled with a core drill, without any intermediate fitting, and preferably approx. at a 45-degree angle. By this solution one can save about hundred “T” profiles in the case of a sports field according to the illustrated embodiment. A protective-stabilizing geotextile layer 5 similar to the geotextile 8a is spread on the collecting pipes 7 embedded by 25-30 cm in the sand layer H laid on the foil 4 and on the ground 1. In the crushed stone layers 2a, 2b, the water moves rapidly against a small resistance, which, in addition to storing the water, solves problems of both the immediate drainage of the rainwater and the rapid introduction of the water required for wetting. The collecting pipes 7 preferably open into a two-chamber basin M provided with control means 15 and installed longitudinally next the field structure S, as shown in FIG. 5, below the water level of the field structure S, preferably below the level of foil 4, so that they get across the foil 1 in a watertight collar G.

[0038] The collecting pipes 7 are in direct communication with the first chamber 11 of the two-chamber pool M, which is connected to the second, larger volume chamber 12 of the two-chamber pool M by a remote-controlled sluice opening 13. The lower flow level A of the sluice opening 13 is below the lower crushed stone layer 2a, in this embodiment below the same level of the film 4, so that the field structure S can be safely emptied to the level of the film 4 if necessary. The water level of the chamber 11 is always the same as the water level stored in the field structure S due to a design corresponding to a communicating vessel. In the event of precipitation, the water level in the field structure S and consequently in the chamber 11 also rises. The water level sensor 16 of the chamber 11, e.g. a pressure measuring cell located in a protective tube 10, sends a signal corresponding to the change in water level to the control means 15, which opens the lockable sluice opening 13. Thus, the excess water entering the layer 9 is discharged from the field structure S into the chamber 12 substantially immediately before it can flood the field surface P. The overflow of the second larger chamber 12 for storing operating water is prevented by the lower overflow opening 23 having a lower flow level situated below the lower flow level A of the sluice opening 13, through which the amount of water that can no longer be stored enters the open air or an additional storage unit. If there is a minimum water level in the chamber 12, which is monitored by a level sensor 17, the control means 15 rises it again by opening a valve 26 connected to a water source. The water level in the chamber 12 is set to a minimum in order to have the largest possible storage capacity to receive the rainwater, which can be economically recycled for wetting the field surface P, e.g. instead of using expensive, cleaned mains drinking water.

[0039] If it is required to wet the field surface P and the water level of the chamber 11 is below the level of the geotextile 8a, a submersible pump 14 raises the stored operating water back into the chamber 11 through a pipe 14a, thus raising the water level in the field structure S until the water level reaches the level from which sufficient moisture flows up in the layer 9 near the field surface P due to the capillary effect.

[0040] This quick and direct control prevents the surface P from being flooded by a possible downpour and even puddles cannot be created, thus ensuring weather/precipitation-independent use, which is essential, especially during races. The control means 15 can be controlled via the Internet, even with a smartphone. The control means 15 is preferably provided with a recording and monitoring system which monitors and records data on water consumption, energy consumption, temperature change, as well as the time and result of the interventions, charging and discharging time intervals and the occurrence of rainfalls. Data series can be displayed e.g. in graphical form on a remote screen. The two-chamber pool M can be covered with a lightweight roof structure that protects the M pool equipment as well as the control means 15 from the effects of the weather.

[0041] In a preferred embodiment of the arrangement for controlling the soil moisture of a sports field according to the invention, the layer order of the field structure S is as follows: [0042] a tread layer 9—120 mm in thick, washed quartz sand or sand-textile mixture, [0043] grid 8—10 mm thick, GM720 geogrid, extruded flexible mesh, [0044] geotextile plate 8a—of 200 g/m.sup.2, [0045] layer 2b—50 mm thick crushed stone with a grain size of 4-11 mm, [0046] layer 2a—100 mm thick crushed stone with a grain size of 11-22 mm, [0047] geotextile 150 g/m2, [0048] foil 4—BTL 30A pond foil, [0049] sand layer H—20-30 mm sand cover, [0050] compacted subsoil 1.

[0051] The advantage of the arrangement for adjusting the soil moisture of a sports field according to the invention over the prior art solutions is that the thickness of the field structure S can be reduced by at least half, thus allowing a cheaper and faster construction than before, and the grid 8 and geotextile plate 8a are significantly cheaper and provide a more even and resilient load distribution on the crushed stone layer 2b, but at the same time greatly inhibit the horizontal displacement of the tread layer 9 during training, competitions, track maintenance, and folding up of edges of the foil 4 above the upper plane of the layer 9 guarantees that no water can drain out of the system uncontrollably, and that a geogrid strip 22 provided with a geotextile installed in an inverted position between the grid 8 and the folded part of the foil 4 allows the necessary movement of air. Another advantage is that it saves water because it uses rainwater originated from the field structure S for rewetting it, thus significantly reducing the use of irrigation water from the water network or wells as compared to conventional fields, while the water level of the field structure S can be controlled easily, quickly and reliably.