FR2492862A1 - Multilayer substrates to support and drain special turf - may include expanded or hydrophilic particles and a non:woven fabric to protect drains from fines - Google Patents

Abstract

Prepd. turf is laid over a substrate prepd. for drainage, via layers of sand, gravel and porous pipes, where the substrate is covered with a non-woven fabric to prevent fine particles of soil, etc. penetrating and clogging the substrate. For warm, dry climates, the build-up may include layers incorporating particles of a hydrophilic material, e.g. urea-formaldehyde based resin, to retain moisture. For damp climates, the turf base may incorporate particles of material which inhibit compaction, e.g. expanded polystyrene. Used for covering sports fields, embankments, etc. sewn with suitable blends of deep rooting grass to withstand erosion and having the roots in a mixt. of compost and river sand overlying a substrate of sharp sand/gravel/pebble.

Description

 The invention relates to the construction of grassy areas, in particular sports fields, and more particularly football and rugby fields.

 Sports fields are generally drained. However, on certain sites, drainage is insufficient, depending on the nature of the soil and the subsoil. It is ineffective in clay soil. In addition, the growth of the grass is uneven: it is satisfactory on the location of the drains, it is weak and irregular between the drains, which causes inequalities detrimental to the practice of a game.

 In addition, in front of the goals and in the center of the field or any other strongly trampled place, the ground compacts, which causes the disappearance of the lawn by asphyxiation and breakage of the roots. This stripping of the most stressed surfaces seriously disrupts the game, restricts the use of land and leads to repeated and costly repair and maintenance work.

 The object of the present invention is to overcome these drawbacks and to allow sustainable and intensive use of these lands.

 The subject of the invention is a method of building land on a stabilized bottom, on which a draining layer is placed, protected by a veil of non-woven fibers. I1 is permeable, but prevents fine particles of the compost from being entrained in the draining layer, thus causing clogging of the latter and compromising the remediation of the soil.

On this veil is placed a substrate of topsoil, river sand and appropriate amendments, which is then sodded with a special lawn of exceptional resistance.

 After the disbursement of the form bottom, it is leveled on the roof (with a slope which can be, for example, 2 cm per meter) and stabilized. Advantageously, this stabilization can be carried out using lime, if the terrain requires it.

 A perimeter trench is open on the perimeter of the land, in order to receive a drain coated with stones, the outlets of these drains being directed either to an existing network, or to stone wells created for this purpose.

 On the shaped bottom thus formed is placed a draining layer (about 20 cm thick) composed of a bed of pebbles, then gravel, and finally a layer of thin sand.

 It is on this layer that the veil is spread. This is preformed into rolls which are unrolled by placing them side by side, with a slight overlap, to cover the entire surface.

 The nourishing substrate consists essentially of a mixture of topsoil and river sand, in a variable proportion depending on the nature of the topsoil used. This mechanically screened and mixed compost is of constant homogeneity, without stones or detritus.

 In the upper part of this layer are incorporated the necessary amendments, determined by the preliminary analysis of the earth.

 In front of the goals and in the center of the field, or in any other strongly trampled place, an anti-compacting product is incorporated ensuring the elasticity and ventilation of these surfaces. In hot and dry climates, a soil improver (synthetic resin based on urea / formaldehyde for example) is added which allows the retention of rainwater or darling to then restore it, according to their needs, to the roots of the lawn.

 The layer of land thus formed is leveled and compacted mechanically, also on the roof, with a slope of 1 cm per meter, with absolute precision.

 The seedbed is then prepared by light harrowing with a vibrating harrow and a picking roller. The seeding is carried out by means of a suitable seeder ensuring a regular distribution of the seeds, their burying and rolling after sowing.

The seed used is a special composition of grass
BENSUN A 34 Kentucky blue grass (75%) and PENNEFIN ray fat (25%).

The lawn BENSUN A 34 Kentucky blue grass from "poa pratensis" is a lawn with strong roots, the many rizhomes of which hang securely in the ground, avoiding any tearing and allowing it, if it is scalped during the game , to cover itself, without new seeding.

PENNEFINE ryegrass, which is also a short-stranded, straight-strung turf, is mixed with BENSUN A 34 to allow faster emergence and promote slower establishment.
BENSUN A 34, which then provides durable and solid lawn coverage.

 Grassing can also be carried out by placing BENSUN A 34 turf in rolls, which allows a rapid start-up of the land, which can take place 2 to 4 months after the veneer, instead of 9 to 12 months for a lawn sown.

 After sowing, as well as after plating, an organic nitrogen fertilizer is spread on the cover on the new lawn.

This non-washable fertilizer promotes germination and recovery of the grass without risk of burns.

 A cross-section of the terrain showing the invention clearly is given in the attached figure.

 In this example, the stabilized form I bottom, established on the roof, has a slope of 2 cm per set. It is surrounded by a trench 2 40 cm deep and wide in which is placed the drain 3 coated with stones.

 On this shaped bottom is placed a layer of pebbles 4 of I5 / 25 of I2 cm thick for example. A layer of gravel 5 of 5 / I5 is placed on the layer of pebbles, and is coated with a weak uniform layer of coarse sand 6.

 The draining layer thus formed on the form bottom thus has a thickness of 18 to 20 cm.

 It is on this surface that the protective vile 7 is deposited.

 A substrate 8 composed of topsoil and river sand is placed on it, the whole being screened and mechanically mixed beforehand. It is then incorporated, with a strawberry, on the upper layer of the substrate 9, the fertilizers and amendments as well as an anti-compacting product in front of the goals, in the center of the field and in any other heavily trampled place. This product is made from 4 to 8 mm expanded polystyrene flakes, rot-proof and chemically neutral.

 The thickness of the substrate, after incorporating these elements, is of the order of 20 to 25 cm after treading and leveling with a special grader: The roof shape of the ground is preserved, with a slope of 1 cm per meter.

 on this surface having undergone a uniform settlement that is prepared the seed bed or veneer of the new lawn IO.

Claims (9)

R E V E N D I C A T I O N S  1. A method of constructing a grassy area consisting in determining a shaped bottom on which a draining layer and a layer of nourishing substrate which are sodded are successively deposited, a method characterized in that a veil of fibers is spread over the draining layer non-woven, and that on this veil is then placed the nourishing substrate, so that the fine particles of this upper layer cannot pass through the veil and then plug the draining layer.  2. Construction method according to claim 1 characterized in that the draining layer is deposited on a stabilized bottom form of a pitched roof, the bottom of which is surrounded by a trench receiving a coated collecting drain.  3. Method according to claim 2, characterized in that the form bottom is stabilized with lime.  4. Method according to claims 1 and 2 characterized in that the draining layer consists of pebbles over half its thickness approximately, covered with gravel, then a few centimeters of sand.  5 Method according to claim 1, characterized in that the nourishing layer consists of a compost of topsoil and river sand, with amendments to the upper part.  6. Method according to claim 5, characterized in that, among the amendments, there are incorporated anti-compacting and soil-improving products for heavily trampled areas, and in particular expanded polystyrene flakes.  7. Method according to claim 5, characterized in that lton incorporates products allowing the retention of water, in particular a synthetic resin based on urea / formaldehyde, on the grounds of hot and dry regions and having only irrigation weak or occasional.  8. A method according to all of the preceding claims characterized in that one proceeds to the compaction and mechanical leveling, the assembly ensuring the homogeneity and the steadiness of the ground, without possible deformations.  9. Grassed area constructed according to all of the preceding claims, characterized in that the nourishing layer is sodded by sowing or by plating, with a turf B fSUN A 34 with rhizomes and roots plunging deep into said nourishing layer so that the roots and rhizomes are very deeply anchored in the soil, thus avoiding uprooting.