EP0768432A1 - Drainage system and method for earth and walls using a granular material - Google Patents

Abstract

The procedure consists of digging trenches round the site to be drained and filling them with bags (1) of a supple material. The bags are shaped to fill the trenches and reinforced by an inner frame. The bags are filled with ground porous volcanic rock, e.g. pozzuolana with a grain size of 30-90 mm, and pref. 40-80 mm. The bags containing the ground pozzuolana are made from Polyene (RTM) or a geo-textile material which is biodegradable. The bags have at least one lengthwise face perforated with holes of under 30 mm diameter. Each bag opens along one face and has flaps (5) which allow it to be closed once filled.

Description

The present invention relates to a method and a system for draining floors and walls using a granular material.

The technical sector of the invention is the field of public works and building.

One of the main applications of the invention is the production of drains for draining excess water retained in the ground around building foundations, in order to limit and even prevent any entry of moisture if not of flooding in these constructions.

There are in fact known various techniques for this, the main ones being either the filling of trenches made around the construction to be protected, with pebbles or other granular and heavy materials which are poured into it in bulk, or a combination of layers of said rollers or other materials above pipes pierced with orifices and arranged at the bottom of the trench; in most cases, in order to avoid clogging of the drainage pipes and / or of the intergrain spaces of the material with which said trench is filled, by the earth entrained by the flow water from the surrounding land which is desired sanitize to protect buildings, at least the wall of said trenches is lined on the side of these lands, before the removal of pipes and / or rollers, for example, of sheets of a porous flexible material, the porosity of which is ensured, either by the weaving of the material, either by perforations.

• la demande FR 2.608.652 déposée sous priorité japonaise et publiée le 26 juin 1988, portant sur une feuille de drainage pour travaux de construction, formée par une première feuille ayant des saillies contenant de l'air, et une seconde feuille collée à la précédente pour que les cavités desdites saillies soient fermées de manière étanche, l'ensemble étant placé dans une feuille d'un non-tissé, afin de réaliser un masque asséchant,
• ou la demande de brevet FR 2.606.435 publiée le 13 mai 1988 et portant sur un procédé et dispositif pour le drainage des rives de toute aire stabilisée de génie civil ou des rives d'une construction, par lequel on dispose à l'intérieur d'une tranchée pratiquée dans le sol, un élément vertical de drainage comportant une enveloppe filtrante, dont le fond renferme un tuyau de drainage ou une cuvette d'écoulement que l'on remplit ensuite d'un matériau granuleux en vrac, pour constituer un massif vertical filtrant dont on rabat les bords de l'enveloppe supérieure de la gouttière constituée sur le dessus du massif.

To improve these techniques, various innovations have been developed and proposed, some of which have been the subject of patent applications, such as:

• application FR 2,608,652 filed under Japanese priority and published on June 26, 1988, relating to a drainage sheet for construction works, formed by a first sheet having projections containing air, and a second sheet bonded to the previous one so that the cavities of said projections are sealed, the whole being placed in a sheet of a nonwoven, in order to produce a drying mask,
• or patent application FR 2,606,435 published on May 13, 1988 and relating to a process and device for the drainage of the banks of any stabilized area of civil engineering or of the banks of a construction, by which one disposes inside of '' a trench made in the ground, a vertical drainage element comprising a filtering envelope, the bottom of which contains a drainage pipe or a drainage basin which is then filled with a loose granular material, to constitute a solid vertical filtering, the edges of the upper envelope of the gutter formed on the top of the bed are folded down.

We can also note the patent application EP 85742 under Japanese priority and published on August 17, 1993 on a method to improve soft soil by the method of sand drains made by cylindrical bags inserted by casing in said soil, so that the shape external may be subject to a large increase in load, or even patent application EP 20630 under Swedish priority, published on January 7, 1981 and relating to a drainage pipe comprising an outer tubular casing provided with several grooves and partitions extending towards the high from the respective edges of said grooves.

These various devices and many others, despite the use of an outer and perforated protective envelope, do not prevent after a few years, a certain clogging of said perforations and / or of the granular material itself which does not allow more then normally the flow of water from the ground through the drain thus formed: in fact, in particular, the retention of the leaves of said flexible materials against the walls of the trench during its filling, is difficult to ensure and comprises numerous defects, mainly due to their collapse in places, and of course reducing its effectiveness.

In addition, the use of rollers or other heavy granular materials requires handling and transport equipment that is fairly heavy, bulky and slow to implement, thus increasing the price of returns from the operation. The extraction of pebbles in quarries in river beds is more and more controlled and limited.

The problem posed is therefore to be able to carry out a drainage of the soils with materials which are added to them, as is known up to now, but with an efficiency which is guaranteed for long periods, with a setting in place and implementation quick and simple, either with the least possible site equipment, and for an overall cost of the supply of the material and its implementation, as low as possible.

• on réalise préalablement des sacs dont l'enveloppe formant poche est constituée dudit matériau souple, et dont les parois sont renforcées et maintenues par une armature à des dimensions correspondant à ladite excavation, soit de préférence légèrement inférieures aux dimensions de celle-ci,
• on remplit lesdits sacs de pouzzolane,
• on transporte lesdits sacs remplis jusqu'à ladite excavation dans laquelle on les dispose les uns contre les autres.

A solution to the problem posed is a soil drainage process, in which an excavation is dug before depositing in it a rigid granular material, enclosed in a sheet of a porous flexible material (either perforated or permeable ). According to said process:

• bags are produced beforehand, the envelope forming a pocket made of said flexible material, and the walls of which are reinforced and maintained by a frame of dimensions corresponding to said excavation, that is to say preferably slightly smaller than the dimensions of the latter,
• we fill these bags with pozzolana,
• said filled bags are transported to said excavation in which they are placed against each other.

Another solution to the problem posed is a soil drainage system, comprising at least one bag whose envelope forming a pocket consists of a sheet of porous flexible material, either perforated or permeable, and stiffened by a frame giving it said desired shape, which bag being filled with the same granular material in rigid fragments, of particle size as defined below and which is pozzolan. The objective of the present invention is also obtained by a bag for soil drainage comprising an envelope forming a pocket and made of flexible material and a basket frame consisting of a trellis giving its shape and corresponding to the dimensions of said envelope, which is porous, at least on two opposite faces.

In a preferred embodiment, the envelope is made of "polyane" or non-woven geotextile; its walls can be stiffened by an inner basket around which it is threaded to be then filled with pieces or grains or fragments of said pozzolan, which is poured inside by one of its opening faces, by any means which can be automated. The envelope is then closed by flaps which are held together to allow the handling of said filled bag and its transport in any position.

In order to be able to make drains with vertical walls around the foundations of constructions, the excavation carried out is then a trench, in which said bags can be placed one behind or in succession and against the other, with or without a connection sleeve between them , in order to form a continuous chain, said bags then being of rectangular or cylindrical shape, the thickness of which can be slightly less than the width of the trench produced.

Thus, for example, a trench of the order of 20 centimeters wide by 50 to 60 centimeters high, can receive rectangular bags 14 to 15 centimeters thick, for a height equal to the depth of the trench and d '' a length of 60 to 80 centimeters: taking into account the low density of the pozzolan which is of the order of 1, or 0.980, each bag having such dimensions, has a maximum weight of 50 kilos which can make it easy to handle by one man in hand without machinery or handling equipment; this weight is in fact the maximum authorized by labor regulations in France and the bags can be fitted with handles to facilitate transport and handling.

The result is new soil drainage methods and systems, responding to the problem posed without having the disadvantages of the methods known to date.

Indeed, the provision in stiffened bags of granular material directly placed in the trenches, eliminates any risk collapse of the flexible wall thereof during filling, ensuring its effectiveness for long periods; the low relative weight of the bags thus produced does not require any handling device, nor any particular transport, thus reducing the costs of implementation, the latter being able to be carried out with great speed.

In addition, such a method according to the invention makes it possible to dig trenches, just or barely larger than the dimensions of the bags prepared because these can be placed immediately after digging the trench and without waiting, whereas in the processes known to date, it is necessary to have a wider trench, on the one hand, to allow handling equipment to be able to access it and dump their material there without risking putting too much aside, and in case of 'landslide, to still maintain a sufficient trench width and this all the more that the filling is necessarily offset from the digging.

In addition, the choice of pozzolan as a granular material, in addition to its lower density allowing the process of implementation according to the invention all the more, allows better resistance to temperature because on the one hand, pozzolan, called also “LAPILI” in Italy, is a good insulator, leaves an always free passage between its grains and resists frost well: its qualities are known and already used even since Roman times as aggregate in insulating cements in certain constructions near places of production that are Auvergne in France, and certain Italian regions.

Pozzolan is indeed a variety of rock of volcanic origin with alveolar structure, formed of slag which has remained in a loose state, which is found in very large quantities in volcanic massifs: its mechanical characteristics are, in particular, its low density of 0.980 due, among other things, to its porosity, but also a good coefficient of thermal and sound insulation, an ability to withstand large and sudden changes in temperature, a roughness of grain, a richness in various natural components and a fairly good compactness and clean rigidity, avoiding its crushing, mechanical resistance to impact, wear and aggressive agents, all of whose characteristics are well known and to which reference may be made elsewhere.

The use of this material has been effectively developed in applications, such as lightened and insulating concrete, and even refractory, or as a binder or undercoat in road techniques and sports equipment floors, respectively due to its reaction to lime and its porosity, or as a soil amendment in agriculture thanks to its richness in silica, phosphorus and among other things the trace elements, or finally in the purification of waste water due to its roughness which attracts bacteria. However, despite its multiple possible applications, the quantity of this material exploited to date is relatively low, which makes it possible to have very large quantities, much less limited than the rollers, which are found only in the bed. rivers and whose operation diverting these, creates major environmental problems which are very controlled to date.

Furthermore, the choice of "polyane" or a nonwoven geotextile as an external flexible envelope is a good compromise between the minimum elasticity necessary for its implementation, a low coefficient of elongation to avoid too much deformation during the filling and transport and very good tear resistance, even after perforation. In addition, the cost price is quite low because they are materials used in many packages. The characteristics of the "polyane" are in particular a tensile strength of the order of 80 kg / mm ² , with a low coefficient of elongation of the order of 0.65 mm / kg in bi-layer and 0, 85 mm / kg in tri-layer; those of nonwoven geotextiles are preferably needled, with continuous filaments, and for various thicknesses, make it possible to obtain tensile and tear strengths, still greater than those of "polyane", with a lower coefficient of elongation , such as, for example for a 1.1 mm thick geotextile, a weight of 85 g / m ² , giving a tensile strength of 5 kN / m, a deformation at maximum effort of 60/50 %, a tear resistance of 0.3 kN / m, puncture resistance of 0.4 kN, filtration opening of 120 microns, and for geotextile 1.4 mm thick and 125 g / m ² in mass surface, characteristics respectively in the same order as for the previous thickness of 8 kN / m, 60/50%, 0.4 kN / m, 0.5 kN and 100 microns, and for a thickness of 1.7 mm and 160 g / m ² , characteristics respectively of 10 kN / m, 60/52%, 0.6 kN / m, 0.7 kN and 97 microns; these characteristics are measured in accordance with standards NFG 38014/38015/38019 and 38017 and may correspond to geotextile material such as that manufactured by the company BIDIM GEOSYNTHETICS SA or equivalent.

"Polyane" is also a biodegradable material after several years, of the order of five years, which is a period corresponding to that allowing the soil to stabilize and therefore no longer risk clogging the interstice of the grains of the pozzolan, once the "polyane" has disappeared, thus keeping the efficiency of the drain.

The choice of particle size is also innovative in the context of the invention between a too small particle size, which would weigh down the bags and which would reduce the drainage effect, and a too large particle size which would require a larger bag width, and therefore larger trenches, which would bring no additional benefit to the efficiency of the system, while reducing its cost.

We could cite other advantages of the present invention, but those mentioned above already show enough to prove its novelty and interest.

The description and the figures below represent exemplary embodiments of the invention, but are in no way limiting: other embodiments are possible, within the scope and scope of this invention, in particular by changing either the basic shape of the bags of the drainage system according to the invention, which could be other than of rectangular or cylindrical parallelepiped shape, or their arrangement in the ground, or both. In particular, the bags according to the invention could be used in horizontal sub-layers drainage under surfaces to be built, such as tennis courts or the like, by placing flat rectangular bags to cover the whole of the desired surface, and not vertical in trenches, as shown in FIG. 2; another use can be in vertical sump with cylindrical bags, according to Figure 4, arranged along their vertical axis.

Figure 1 is a perspective view of an example of a bag 1 with a frame 3 consisting of internal stiffeners.

FIG. 2 is a trench representation with bags 1 making drains according to the invention, such as those of FIG. 2, but bags according to Figures 3 or 4 could also be used.

Figure 3 is a perspective view of another embodiment of a bag 1 with an internal basket of welded mesh of flexible steel, flexible iron or plastic, and with meshes between 0.03 x 0.03 meter, up to 0.250 x 0.250 meter and even beyond, and diameters of wire constituting said trellis from 2 to 6 millimeters.

Figure 4 is a perspective view of another example of a bag 1 according to the invention, with a frame of the type of that of Figure 3, but of cylindrical shape.

The envelope shown here in all the drawings as being exterior 2 is made of a flexible, porous material, either perforated when it is "polyane", or permeable when it is a non-woven geotextile, and stiffened by an inner frame 4 made up of fairly spaced stiffeners as in Figure 1 or of a welded mesh basket, as shown in Figures 3 and 4: this frame 4 gives it any desired shape; the internal volume 7 of said bag 1 is filled with pozzolan 11, with a particle size between 30 and 90 millimeters and preferably 40 to 80 millimeters. In another embodiment, said stiffeners or frame 4 could be arranged outside and in a particular implementation, be assembled after filling of said envelope, by "sandwiching" it between two frame frames, for example planes, forming the two longitudinal faces of a parallelepiped, and interconnected by rods making tie rods 14, for example of 0.010 meters in diameter through the bag, and immobilized on the external longitudinal reinforcements by any fixing system, with stop washers 16 of 0.02 meters in diameter for example, such as those shown in figure 3.

All the faces 2 of said envelope are porous, either in the case of "polyane" perforated by orifices 12 with a diameter less than the smallest of the value of the range of particle size chosen, ie 30 millimeters, and preferably 22 millimeters, and even with micro holes of 0.06. The casing 2 is made up of one to three thicknesses of sheets or layers of "polyane" preferably, for better resistance and could be placed inside the stiffeners, as indicated above. In the case of a nonwoven geotextile envelope as defined above, it being permeable does not need to be perforated and existing in several thicknesses, it is not necessary to have it in several layers.

In FIGS. 1, 2 and 3, the bags are shown in the shape of a parallelepiped, and as indicated previously, they can be of another shape, such as cylindrical, as in FIG. 4. Whatever their shape, they comprise at at least two opposite parallel faces 2 ₂ : in their application as a trench drain according to FIG. 2, these faces 2 ₂ are arranged vertically and come into contact with one another between adjacent bags to constitute a continuous drain; one of these faces 2 ₂ can be equipped with a hollow connection sleeve 13, as shown in FIG. 1, manufactured as the casing 2 from 0.15 to 0.20 meters long for example, to ensure continuity in threading it around the end of the adjacent bag.

In the parallelepipedic embodiment, the perforations of the envelope 2 of said bags 1 are less numerous on one of the longitudinal faces 2 ₁ than on the others, of the order of about 1 / 10th and corresponding to the side which is exposed to the ground 9 to be sanitized to protect the side corresponding to the ground where the construction 10 is located, which we want to isolate from said ground 9, as shown in FIG.

In a type of evacuation of used water in a vertical sump of cylindrical shape, the perforations are only made on the flat faces 2 ₂ opposite ends, the wall of the peripheral casing 2 ₄ being non-perforated.

The envelope 2 of the bag 1 opens on one of its faces, such as at its upper part opposite to the face 2 ₃ of its bottom which comes into contact with the bottom of the trench 8 or excavation; the opening can also be on a side face 2 ₂ then arranged vertically for filling, and preferably on the face which carries the socket sleeve 13, although in Figures 1 and 2 attached this opening face is arranged on a face different from that of the sleeve, to clearly show that different possibilities are possible. This envelope face opens to allow filling which can be carried out directly on the extraction site of the pozzolan and of its production in the desired particle size: this opening is then closed by flaps 5 ensuring the closure of the bag, by welding, bonding by press system or by any mechanical means, such as by eyelets 6 pre-punched in the flaps and through which a strap or a rod can be passed.

As regards the frame formed by stiffeners 4 and / or a basket 3 making it possible to reinforce and give the desired shape to the casing 2, and to maintain the latter during transport and handling, said stiffeners 4 are arranged at least along the edges delimiting said shape of the bag 1 and at least along a median on all the faces 2 delimited by said edges, except those corresponding to the filling opening. For a rectangular parallelepiped shape as shown in Figure 1, corresponding to an application in a trench 8 as shown in Figure 2, we then have at least: four vertical stiffeners 4 ₁ in the four vertical edges, two vertical stiffeners 4 ₂ in the middle of the two longitudinal faces 2 ₁ and interconnected at their bottom at the bottom 2 ₃ , eight horizontal stiffeners 4 ₃ along the bottom edges of the bottom 2 ₃ and the top face corresponding to the opening, four horizontal stiffeners 4 ₄ interconnected in the same plane and sharing the median longitudinal sides 2 ₁ and lateral sides 2 ₂ .

• soit des raidisseurs diagonaux 4₅ dans les deux faces longitudinales 2₁, comme sur la figure 1,
• soit d'autres raidisseurs verticaux et horizontaux formant une armature en treillis 15, comme représenté sur la figure 3 dans les faces longitudinales 2₁ et horizontaux et croisés également en treillis dans le fond 2₃, et reliés à ceux des faces latérales et longitudinales à leur partie inférieure,
• soit comme pour la solution d'armatures externes, et représentées également sur la figure 3, des tiges 14 de diamètre 0,010 mètre par exemple et de longueur égale à la largeur 1 du panier 3, et faisant tirants à travers le sac entre les faces longitudinales 2₁ qu'elles relient, et immobilisées par exemple par des rondelles 16 extérieures de diamètre 0,02 mètre par exemple,
• soit une combinaison de ces diverses possibilités.

In addition, to reinforce the stiffening of the external and especially longitudinal faces or walls of the bags 1 according to their dimensions, it can be arranged:

• either diagonal stiffeners 4 ₅ in the two longitudinal faces 2 ₁ , as in FIG. 1,
• or other vertical and horizontal stiffeners forming a trellis reinforcement 15, as shown in FIG. 3 in the longitudinal 2 ₁ and horizontal faces and also crossed in trellis in the bottom 2 ₃ , and connected to those of the lateral and longitudinal faces at their lower part,
• either as for the solution of external reinforcements, and also shown in FIG. 3, rods 14 of diameter 0.010 meters for example and of length equal to the width 1 of the basket 3, and making ties through the bag between the longitudinal faces 2 _{1 which} they connect, and immobilized for example by external washers 16 with a diameter of 0.02 meters for example,
• or a combination of these various possibilities.

The spacing between the stiffeners can be 30 to 120 millimeters and even more, depending on the particle size chosen for the pozzolan grains, because the smaller this particle size, the more the dimensions of the mesh defined by the spacing of the stiffeners will have to be reduced. to avoid excessive deformation of the envelope 2.

All of these stiffeners are preferably integral with each other and even welded and / or molded from one or more pieces to form an inner basket 3 around which said casing 2 is threaded: preferably, said stiffeners are produced, either by steel or flexible iron, either plastic, of hard PVC type, in rods with a diameter for example of the order of 4.5 millimeters for vertical and horizontal stiffeners, and 3 millimeters for those arranged in diagonal, all of these stiffeners being within a range of 2 to 6 millimeters in diameter.

As an example of sizing for bags of the rectangular parallelepiped type as shown in FIG. 1 for the application according to the representation in FIG. 2, the length L of said bags can be from 0.50 to 1.20 meters, for a height h of 0.40 to 0.80 centimeters and a width l of 0.10 to 0.15 meters, so therefore for example: L xhxl = 0.60 x 0.60 x 0.14 meters or 0, 70 x 0.50 x 0.14 meter or 0.80 x 0.40 x 0.15 meter; therefore in fact a thickness l of between approximately 20% and 40% of the smallest of the other dimensions L and h; these are of equal value, or at most, one is double the other.

For cylindrical type bags, their diameter D can be from 0.2 to 1.20 meters.

Claims (10)

Method of draining soils, in which an excavation (8) is dug before depositing in it a rigid granular material, enclosed in a sheet of a porous flexible material, characterized in that: bags (1) are produced beforehand, the envelope (2) of which forms a pocket and is made of said flexible material and the walls of which are reinforced and maintained by a frame (4) with dimensions corresponding to said excavation, - said bags (1) are filled with pozzolan (11), - Transporting said filled bags (1) to said excavation (8) in which they are placed against each other. Soil drainage system comprising a sheet of porous flexible material enclosing granular rigid material, characterized in that it comprises at least one bag (1) whose envelope (2) forming a pocket is made of said flexible material and stiffened by a frame (4) giving it said desired shape, which bag (1) being filled with pozzolan (11). Soil drainage system according to claim 2, characterized in that said pozzolan (11) has a particle size between 30 and 90 millimeters, and preferably 40 to 80 millimeters. Soil drainage system according to any one of claims 2 or 3, characterized in that the bags (1) are of rectangular shape and the envelope (2) is perforated with fewer perforations on a longitudinal face (2 ₁ ) than the others. Floor drainage system according to claim 4, characterized in that said perforations are of a diameter less than 30 millimeters. Soil drainage system according to any one of claims 2 to 5, characterized in that said envelope (2) is made of biodegradable material having a tensile strength of around 80 kg / mm ² and a low elongation coefficient of around 0.65 mm / kg. Floor drainage system according to any one of Claims 2 to 6, characterized in that the said envelope of the bags (1) opens on one of its faces and has flaps (5) ensuring its closure. Floor drainage system according to any one of Claims 2 to 7, characterized in that the reinforcement (4) is formed by stiffeners (4) arranged at least in all the edges delimiting the shape of the desired bag (1), and at least along a median of all the faces delimited by said edges, except in that corresponding to the filling opening. Soil drainage system according to any one of Claims 2 to 8, characterized in that the said walls of the envelope (2) are held and stiffened by an inner basket (3) of welded mesh with meshes of at least 0 , 03 x 0.03 meter and around which said envelope (2) is threaded. Bag (1) for soil drainage comprising an envelope (2) made of flexible material and a frame (4) giving its shape and corresponding to the dimensions of said envelope (2), which is porous, at least on two faces 2 ₂ opposite, characterized in that said bag (1) is filled with pozzolan, said envelope (2) forms a closed pocket and the frame (4) in basket (3) consists of a trellis.

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