WO2018124866A1

WO2018124866A1 - Device for soil stabilisation using a covering of straw secured by wire mesh and a method for seeding banks in order to control erosion

Info

Publication number: WO2018124866A1
Application number: PCT/MA2017/000040
Authority: WO
Inventors: Abdelkrim DERRADJI; Chawki FAIZ; Nourredine TLEMÇANI
Original assignee: Société Nationale Des Autoroutes Du Maroc (Adm)
Priority date: 2016-12-28
Filing date: 2017-12-27
Publication date: 2018-07-05
Also published as: MA39584B1; MA39584A1

Abstract

The invention relates to a device for soil stabilisation using a covering of straw secured by a wire mesh so as to control the water erosion of the soil, and to a method for seeding the banks with the same purpose in mind. The technique combining the device and the method consists in using materials that are inoffensive to nature and has a double role: stabilising the soil by covering the soil with reed lattices. Said stabilisation measure is temporary and should disappear over time at the same rate as the biodegradation of the constitutive elements. But until then, said stabilisation measure holds the earth and provides the necessary conditions for the growth of the seeds sheltered thereby. The banks are seeded with a finely selected and tested composition of seeds. The method for seeding the banks using the stabilisation device is implemented according to the following steps: preparation of the soil of the terrain susceptible to erosion; spreading out the straw on the terrain; sowing; and securing the straw by a thin metal mesh secured by iron hooks.

Description

FLOOR FIXING DEVICE USING GRID FIXED STRAW BILLING AND TOLL SLAUGHING METHOD FOR FIGHT AGAINST

EROSION

DESCRIPTION

The present invention relates to a method for fixing soils for the control of water erosion.

The field of invention and technical problem raised:

Soil erosion is a natural process responsible for the transport and redistribution of soils through the action of rainwater runoff. In Morocco, water erosion is a major threat to development infrastructure and currently requires a lot of interest from policy makers. This has consequences for the realization of development plans and spatial planning, given the fatal consequences that may affect soil stability, the quality of water, the durability of certain structures such as dams and roads. etc.

Water erosion is also the main source of suspended solids (SS). Excessive transfer of these materials can have undesirable effects on the stability of civil engineering works. Indeed, the concentration of these materials increases the severity of the floods.

This phenomenon is growing and increasing with climate change, as we are facing a significant increase in periods of heat wave and drought interrupted by extreme events of heavy rainfall, this disordered climate causes the detachment of the MES and promotes their transport.

The development of the territory and especially transport infrastructure creates a scar in the natural environment which can have undesirable repercussions, if we do not make the necessary corrections in time and with effective and sustainable techniques. Failure to restore balance As a natural phenomenon, water erosion has a significant impact on transportation infrastructure due to the gorging of structures and the clogging of sewage systems resulting from solid deposits.

Water erosion affects soils in general and especially agricultural soils, and particularly affects land development works (roads, highways, railways, dam, port ...) Soil fixation is a sought-after goal in dealing with the problem of water erosion, however, the extent of the areas to be treated, which can be counted in hectares, requires the use of ingenious techniques which are less expensive and respectful of the environment. 'environment. The present invention claims to provide the most suitable technique.

The state of the prior art:

The civil engineer designs his works in such a way as to limit as much as possible the impact of water erosion, in particular to ensure softened slopes of the embankments in order to prevent the departure of the materials, and even to install fastening works such as shotcrete or material retention structures at the foot of the embankment. However, the phenomenon remains more worrying for the operator of the works because of the frequent operations to be carried out to remedy the damage of the floods. Especially when the surfaces to be treated are important where the cost problem is needed.

Traditional techniques have been developed by farmers to conserve agricultural soils without these techniques being cataloged or industrialized, and we note a great variety of techniques which testify to the adaptation of man to the conditions of the environment. These techniques include:

- The ramps of straws: the establishment of straw barriers.

- Mulching: spreading straw on erosion-sensitive land

- The planing: the ridging parallel to the contours

- The cords of stones: they are stony and porous obstacles

There are also other more elaborate civil engineering techniques that use synthetic materials to stabilize embankments, and replace sensitive soils with a filter material based on a synthetic material retaining the soils of the lower layers. These techniques are expensive and less respectful of the environment, and can only be applied occasionally.

Our invention represents a hybrid version of the mulching technique. The solution provided by the invention: The revegetation of the taius is a process of biology engineering that has demonstrated its usefulness to the phenomenon as well as its respect for the environment and its cost promoter. The object of our invention is to introduce a water erosion control technique that combines soil fixation and revegetation. In fact, this invented technique uses materials that are harmless to nature and ensures a dual role:

- soil fixation by mulching with straw fixed by fine iron roasting: which is ephemeral and supposed to disappear with time at the same rate of biodegradation of the elements that compose it. But by then, this fixation retains the earth and offers the necessary conditions for the thrust of the seeds that shelter there.

^• Revegetation: a finely chosen and tested seed composition will be used to revegetate the slopes.

In the following we will describe the stages of the technique: Step 1: Preparation of the soil of the slope

The embankment must be scarified with the aid of a manual or mechanical toothed tool (rake or harrow). If the embankment is already cleared, fill the ravines with a supply of soil taken from the same slope or from the top of the slope.

Step 2: Spreading straw on the embankment

The straw is spread on the slope previously fertilized with a compound fertilizer, type 14-28-14 at a rate of 100 kg / ha, and amended with compost or manure at a rate of 20 t / ha, ie 2kg / m2 and sowed with a mixture to be prepared according to the climatic and climatic conditions of each target site.

Step 3: Sowing

Sowing on the fly before spreading the straw with a mixture of:

• 10% of shrub seeds: Atriplexsp., Medicagoarborea, Coronilloglauca, Spartiumjunceum, Telinelinifolia, Acacia sp., Retamasp., CalycotumviHosa, Cytisussp., Cistussp., Etc. (the choice of the species depends on the nature of the soil of the slope);

• 20% cereal seed of the barley or oat type;

• 20 to 30% legume seeds: Medicagosp. Trifolium sp. Onobrychisvicifolia, Hedysarumcoronarium, Psoraleabituminosa, Lotus sp. ;

• 40% of perennial seeds: Graminaceae {Lolium, Festuca, Dactylis, Chloris), Sanguisorbaminor, Lavandulasp. Plantagosp., Rumex sp., Calandulasp. Papavumsp. Eschchobia, etc. choice of each of these species depends on the nature of the soil of the embankment). The density of the seedling is about 20 to 30 kg / ha.

The plant species are chosen according to the following criteria: adaptation to edapho-climatic conditions (weather and climate), resistance to erosion and ornamental value. However, large-scale seeding of selected species requires a seed multiplication program to cover large areas of slopes.

Step 4: Attach the straw

The straw cover should be evenly distributed along the slope, using rakes or by simple trampling. The straw is stabilized on the slope by a thin wire mesh fixed with iron hooks.

Results

1st rains: after the rains, one generally notes a good germination, particularly on grasses. Legumes and other multi-flowering species (wild seeds) germinate more slowly depending on seed germination and climatic conditions. The colder it is, the lower the germination rate. The role of straw is among others, the creation of a microclimate to improve the germination rate and emergence of species. If the year is sufficiently rainy, most species will produce enough seeds to build up a seed stock for regeneration in later years.

Shrub seeds are usually the last ones to germinate and can even remain for several years before they can be planted in shrubs. It is these shrubs that will ensure the final cover of the slopes.

The mulching operation has several advantages: o Reduce splash erosion by attenuating the kinetic energy of the raindrops;

o Improve the mechanical characteristics of the soil, particularly its cohesion; o Promote infiltration by increasing the absorption of water; o Ensure the supply of organic nutrients;

o Reduce the evaporation of water, allowing the sown plants to stay on the embankment

Interview

After maturity of the annuals (cereals), it is necessary to carry out a cut, simple to realize, to avoid the risk of fire.

If the first year of installation is particularly dry, it is strongly recommended to re-seed the next season.

Possible industrial applications:

The technique is very promising, as well by its low cost, as its aesthetics, integrating perfectly with the landscape. This technique has been tested and has yielded interesting results, making it possible to switch to a larger scale use on the risk slopes of several sections of the motorway.

This technique has a wide scope and offers an effective solution to the problem of water erosion, including soil fixation in general to stop their accelerated displacement by heavy showers due to climate change. The same technique will also be used to stabilize the soils of the embankments of roads, motorways, railways, LGV etc. and will certainly contribute to soil stabilization around ports and dams.

Claims

1. A soil fixation device for protection against water erosion (1), characterized in that it is formed of straw mulch fixed to the ground by roasting. The fixing device constitutes a shelter from an imposition of adapted seeds.

2. Device for fixing the floor according to claim (1), characterized in that the mulch is fixed to the ground by a wire mesh of small diameter with a mesh size of 2 cm, the mesh is fixed to the ground by round hooks 6 mm thick iron anchored to more than 50cm in the ground, the hooks are distant from 2 m

A method of seeding slopes for erosion control comprising at least the following four steps:

A. A first step is to prepare the soil of the slope by scarification using manual or mechanical tools tooth (rake or harrow). If the embankment is already cleared, fill the ravines with a supply of soil taken from the same slope or from the top of the slope.

B. A second stage during which the seedling is seeded on the fly, or by projection.

C. A third step aimed at spreading the mulch on the slope.

D. A fourth step for fixing the wire mesh with iron hooks.

4. Method according to claim (3) characterized in that the slope is previously fertilized with a compound fertilizer, type 14-28-14 at a rate of 100 kg / ha, amended with compost or manure at a rate of 10 t / ha, ie lkg / m2 and sown with a mixture.

5. Process according to claim 3, characterized by a mixture of seedlings composed of:

• 10% shrub seed: Atriplex sp. Medicago arborea, Coroniella glauca.

Spartium junceum, Teline UnifoUa, Acacia sp., Retama sp., Calycotum villosa, Cytisv sp., Cistus sp., Etc. (the choice of the species depends on the nature of the soil of the slope);

• 20% cereal seed of the barley or oat type; • 20 to 30% legume seeds: Medicago sp. Trifolium sp. Onobrychis vicifolia. Hedysarum coronarium, Psoralea biluminosa, Lotus sp. ;

• 40% of perennial seeds: perennial grasses (Lolium, Festuca, Dactylis.

CA / ora), Sanguisorba minor, Lavandula sp. Plantago sp., Rumex sp., Calandula sp. Papavum sp. Eschcholzia, etc. The choice of each of these species depends on the nature of the soil of the slope.

The seeding density of the total mixture is about 100 to 150 kg / ha, depending on the final composition adopted by slope.