Containing element, structure of reinforced ground, process of making said structure of reinforced ground

Abstract

A containing element to be used in geotechnical applications, including: a facing body made of a cementitious material having an inner face configured for contacting the ground and an outer face opposite to the inner face with respect to the body itself, a monolithic reticular structure made of plastic material having a plurality of first and second elements intersecting each other at respective nodes in order to form meshes. The reticular structure includes a first portion integrated and stably embedded in the facing body and a second portion, integral with the first portion, emerging from the inner face of the facing body; the second portion of the reticular structure defines, cooperatively with the inner face of the containing body, a closed loop.

Claims

1. A structure of reinforced ground, comprising: a plurality of containing elements for geotechnical applications comprising: at least one facing body associable to a ground for defining a containment and support to the ground, the at least one facing body comprising at least one inner face configured for contacting the ground and one outer face opposite to the at least one inner face with respect to the facing body itself, at least one reticular structure having a plurality of first elements spaced from each other and developing along prevalent development paths, the at least one reticular structure having further a plurality of second elements also spaced from each other which extend along respective prevalent development paths along a direction transverse to the plurality of first elements, the plurality of first and second elements intersecting each other at respective nodes in order to form meshes, the at least one reticular structure comprising at least one first portion integrated and stably embedded in the at least one facing body and at least one second portion, integral with the at least one first portion, emerging from the at least one inner face of the at least one facing body, and wherein the at least one second portion of the at least one reticular structure defines a plurality of slots, the plurality of slots, in cooperation with the at least one inner face of the at least one facing body, defining a closed outline loop, wherein the plurality of slots defines, along a predetermined direction, a single channel longitudinally delimited by terminal opposite slots, the at least one reticular structure being made of a monolithic plastic material, said containing elements, according to an operative condition of the plurality of containing elements, being arranged in a vertical position by overlapped rows, each of the plurality of containing elements containing elements exhibiting the at least one second portion of the reticular structure emerging from the at least one inner face of the at least one facing body in order to define the plurality of slots, a predetermined number of monolithic reinforcement nets of a plastic material, each of the predetermined number of monolithic reinforcement nets comprising the plurality of first elements spaced from each other and developing along the prevalent development paths, each of the predetermined number of monolithic reinforcement nets further exhibiting the plurality of second elements also spaced from each other which extend along respective ones of the prevalent development paths in a direction substantially transverse to the plurality of first elements, the plurality of first and second elements intersecting each other at respective nodes in order to form the meshes, at least a series of second elements, of the plurality of second elements, of the predetermined number of monolithic reinforcement nets, comprised between two adjacent immediately consecutive ones of the plurality of first elements, being inserted and interwoven with the plurality of slots of the containing element, the structure further comprising: at least one locking bar engaged inside the channel defined by the plurality of slots so that the series of second elements of each of the predetermined number of monolithic reinforcement nets is interposed between the at least one facing body and the at least one locking bar, the at least one locking bar being configured for stably constraining each of the predetermined number of monolithic reinforcement nets to the plurality of containing elements.

2. The structure according to claim 1, wherein each of the predetermined number of monolithic reinforcement nets exhibits at least one portion placed in a horizontal position inside the ground at a level of a plurality of aligned ones of the plurality of slots.

3. The structure according to claim 1, wherein the at least one locking bar is made of a plastic material.

4. The structure according to claim 1, wherein the second portion of the at least one reticular structure comprises at least the plurality of second elements emerging from the at least one inner face of the at least one facing body and defining said plurality of slots, the plurality of second elements being aligned along a predetermined rectilinear direction and parallel to a prevalent development plane of the at least one facing body itself.

5. The structure according to claim 4, wherein the second portion of the at least one reticular structure comprises, for each linear meter measured along a predetermined direction of aligning slots, a number of the plurality of second elements greater than 10.

6. The structure according to claim 1, wherein the plurality of second elements are stretched along a prevalent development direction of the plurality of second elements after formation of the plurality of second elements and have a structure having molecular chains oriented along the prevalent development direction.

7. The structure according to claim 1, wherein the plurality of second elements are obtained by extrusion and are then stretched, wherein the plurality of second elements have a stretching ratio greater than 3, the stretching ratio of the plurality of second elements being defined as a ratio between a final length of the plurality of second elements after having stretched the plurality of second elements to an initial length of the plurality of second elements before stretching them.

8. The structure according to claim 1, wherein the plurality of first elements are not stretched or have a stretching ratio less than one of the plurality of second elements, the stretching ratio of an element of the plurality of first and second elements being defined as a ratio between a final length of the element once the element has been stretched to an initial length of the element before stretching the element.

9. The structure according to claim 1, wherein the at least one facing body is in a cementitious material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Some embodiments and some aspects of the invention will be described in the following with reference to the accompanying drawings, given only in an indicative and therefore non limiting way, wherein:

(2) FIGS. 1 and 2 are respective perspective views of a structure made of reinforced ground according to the present invention;

(3) FIG. 3 is a lateral view of a containing element, according to the present invention, according to a first embodiment;

(4) FIG. 3A is a detail of the containing element in FIG. 3;

(5) FIG. 4 is a lateral view of a containing element, according to the present invention, according to a second embodiment;

(6) FIG. 4A is a detail of the containing element of FIG. 4;

(7) FIG. 4B is a detail of a containing element according to the present invention;

(8) FIG. 5 is a top view of a containing element according to the present invention;

(9) FIG. 5A is a detail of the containing element in FIG. 5;

(10) FIG. 6 is a perspective view of a containing element according to the present invention;

(11) FIG. 6A is a schematic lateral view of a reinforced ground structure according to the present invention;

(12) FIG. 7 is a lateral view of a containing element, according to the present invention, according to a third embodiment;

(13) FIG. 7A is a detail of the containing element in FIG. 7;

(14) FIG. 8 is a lateral view a containing element, according to the present invention, according to a fourth embodiment;

(15) FIG. 8A is a detail of the containing element in FIG. 8;

(16) FIG. 9 is a lateral view a containing element, according to the present invention, according to a fifth embodiment;

(17) FIG. 9A is a detail of the containing element in FIG. 9;

(18) FIG. 10 is a lateral view a containing element, according to the present invention, according to a sixth embodiment;

(19) FIG. 11 is a lateral view of a containing element, according to the present invention, according to a seventh embodiment;

(20) FIG. 12 is a lateral view a containing element, according to the present invention, according to an eighth embodiment;

(21) FIG. 12A is detailed cross-section view of a variant of an embodiment of a containing element according to the present invention;

(22) FIG. 13 is a schematic view of a portion of a monostretched reticular structure according to the present invention;

(23) FIG. 14 is a schematic view of a portion of a bi-stretched reticular structure according to the present invention;

(24) FIG. 15 is a schematic view showing a possible operative condition of a reinforcement net according to the present invention;

(25) FIGS. from 16 to 18 schematically show operative conditions of reinforcement structures according to the prior art;

(26) FIGS. from 19 to 23 schematically show possible steps of a process of making a ground reinforced structure according to the present invention;

(27) FIGS. from 24 to 26 schematically show some possible steps of a process of making a containing element according to the present invention.

DETAILED DESCRIPTION

(28) Containing Element 1

(29) 1 generally indicates a containing element to be used in geotechnical applications, and in particular for making systems reinforcing and containing grounds. For example, the containing element 1 can find an application in the reinforced grounds for making vertically extending supporting faces and/or walls. Some further applicative examples of the containing element 1 can be represented by natural slopes, green walls, block walls, artificial walls, landslide rehabilitation.

(30) The containing element 1 comprises a facing body 2 associable to the ground for defining a containment and support for the same. De facto, as it will be better explained in the following, the facing body 2 is configured for defining the ground boundary element adapted to receive the thrust of the ground and contain it. As it is visible for example in FIGS. 1 and 2, the facing body 2 comprises an inner face 2a configured for facing and contacting the ground, and an outer face 2b opposite to the inner face 2a with respect to the body itself. The accompanying figures illustrate a preferred but non limiting configuration of the invention so that the facing body 2 substantially comprises a panel having a rectangular or square shape exhibiting a surface extension, defined by the length and width of the same, essentially greater than the thickness. From the dimensional point of view, the panel can exhibit a minimum sizedefined by the length and width of the panelgreater than 0.5, particularly comprised between 1 and 3 m, still more particularly between 1.5 and 2.0 m. From the surface extension point of view, the panel can define an area greater than 1 m.sup.2, particularly comprised between 1.5 and 5 m.sup.2. The dimensions of the panel (surface extension) enable a large face development for ensuring an optimal efficiency during the step of laying and assembling the system for maintaining an optimal flexibility in order to adapt to different design configurations. In case the facing body comprises a panel, this latter would exhibit a thickness defined by the distance between the inner face 2a and outer face 2b of the facing body 2, substantially smaller than the length and width of the same; optionally the thickness of the panel can be less than 20 cm, particularly is comprised between 7 and 18 cm. It is not excluded the possibility of making a facing body 2 comprising substantially a block having essentially the shape of a cube; in this latter case, the thickness would not be substantially smaller than the length and width of the block.

(31) From the material point of view, the facing body 2 can be made of a cementitious material, and particularly of concrete (the panels can be prefabricated, for example). As it is visible in the attached figures, the facing body 2 can further comprise at least one reinforcement 12 embedded inside the body (embedded inside the panel, in the attached figures) and exhibiting, in a non limiting way, a surface development substantially equal to the surface extension of the body 2. The reinforcement 12 can comprise, for example, a grid of metal material, particularly, a resistance-welded grid, exhibiting a varying thickness comprised, in a non limiting way, between 5 and 15 mm, particularly between 5 and 11 mm. The dimensions and the structure of the facing body 2 enable to define panels having a small weight, particularly less than 2000 kg, still more particularly less than 1800 kg.

(32) As it is visible for example in FIGS. from 3 to 12, the containing element 1 comprises at least one monolithic reticular structure or grid 3 of plastic material partially integrated in the facing body 2. The reticular structure 3 exhibits a plurality of first elements 4 spaced from each other and extending along prevalent development paths, and a plurality of second elements 5 also spaced from each other extending along respective prevalent development paths in a direction substantially transversal to the first elements 4; the first and second elements 4, 5 intersect each other at respective nodes 6 in order to form meshes 7 (see FIGS. from 13 to 15, for example). Specifically, the reticular structure 3 substantially defines an integral reticular grid (in other words a monolithic grid obtained in one piece and not by connections such as by gluing or weaving different elongated elements) of plastic material comprising a series of first elements 4 parallel to each other; the first elements 4 are spaced from each other and interconnected by a plurality of second transversal elements 5, which are also parallel to each other. The elements 4 and 5 can be made of plastic materials selected as a function of their physical and mechanical characteristics; for example the elements 4 and 5 can be made of HDPE, PE, LDPE, PP, PVC, PS or of other polymers. In the present discussion, it is understood that each of the first elements 4 extends all along the width of the reticular structure 3, in other words is formed by the plurality of aligned portions along a same line transversal to the reticular structure 3. Similarly, each of the second elements 5 extends along the length of the reticular structure 3, in other words is formed by the plurality of portions aligned along a same longitudinal line of the reticular structure 3: in this way each of the first elements 4 is intersected by a plurality of the second elements 4 and each of the second elements 5 is intersected by a plurality of first elements 4. Advantageously the second elements 5 are stretched along their prevalent development direction (as it will be better described in the following, the second elements are stretched after being formed) and exhibit a structure having molecular chains oriented along such stretching directions. The stretching step provides the second elements 5 with an elongated shape capable of providing the reticular structure 3 with an optimal flexure strength, particularly enables the structure 3 to freely bend along at least one transversal axis substantially parallel to the first elements 4. Particularly, the second elements 5 exhibit a stretching ratio greater than 3, optionally comprised between 3 and 8, more optionally between 4 and 7; the stretching ratio of the second element 5 is defined as a ratio of a final length of the second elements 5 after being stretched (particularly immediately after being stretched) to an initial length of the second elements 5 before being stretched. Particularly, the term before being stretched means immediately after forming the reticular structure 3 (after forming a net defined by precursors of the first and second elements 4, 5) but before the stretching step.

(33) FIGS. from 13 to 15 illustrate reticular structures 3 (grids) exhibiting second stretched elements 5. According to the stretching rate, the second elements 5 exhibit a more or less thin structure, so that they can take also a thread shape; anyway, the second elements 5 exhibit a cross-section that, at a median point between two first consecutive elements 4, is substantially smaller than the cross-section of said first elements 4. Each of these first and second elements 4, 5 exhibits portions extending between consecutive nodes 6. Further, due to the stretching step of the second elements 5, these latter exhibit portionsextending between consecutive nodes 6having terminal areas having a section (measured normal to the main development direction of the second element 5) progressively decreasing from a node 6 towards a centre line of the portions, and a central area having a substantially constant cross-section.

(34) On the contrary, referring to the first elements 4, these latter, in a first embodiment shown for example in FIG. 13, exhibit, in a non limiting way, a substantially unstretched structure (or at most slightly stretched) and a thickness (and a cross-section) constantly greater than the thickness (and cross-section) of the second elements 5. In such configuration, the first elements 4 substantially define more compression-resistant bars capable of having more friction against the ground than the second elements 5. The first elements 4 are maintained unstretched for providing the containing element 1 a determined rigidity and a good capacity of being anchored to the ground.

(35) In a second embodiment illustrated in FIG. 14 for example, the first elements 4 are also stretched along their development in order to define in this way a bi-layered reticular structure. Despite the reticular structure 3 can exhibit a substantially bi-layered structure, it is anyway better to make different the stretch of the first and second elements. Particularly, the stretching ratio of the first elements 4 is at least half the stretching ratio of the second elements 5. In this way it is possible to obtain first elements 4 having an oriented molecular structure and therefore improved from the tensile strength level point of view, but having anyway a stiffer structure than the second elements 5. Particularly, it is preferable that first elements 4 maintain a determined rigidity and a determined bar-shape (not a thread shape) so that the same can ensure a determined grip (anchoring) to the ground. Therefore, in a preferred but non limiting embodiment of the invention, the first elements 4 are not stretched or are slightly stretched: for example, a stretch which does not cause a stretching ratio greater than 1.5, particularly about 1.25.

(36) Now, the analysis of the reticular structure from the dimensional point of view makes possible to define the distances between the first and second elements. Specifically, the distance between two first adjacent elements 4 is comprised between 100 mm and 400 mm, optionally between 200 mm and 300 mm. The overall extension or length of each first element 4 of the reticular structure 3 is slightly less than the body 2 (panel) length and, particularly, greater than 0.5 m, specifically comprised between 0.7 and 2.5 m, still more particularly comprised between 1 and 2 m. The distance between adjacent second elements 5 is comprised between 10 mm and 50 mm, optionally between 15 mm and 30 mm. as these distances change, the dimensions of the meshes 7 change, which can exhibit a through area comprised between 1000 and 20000 mm.sup.2.

(37) Further, the first elements 4, according to a cross-section transversal to their prevalent development direction, exhibit an area greater than 15 mm.sup.2, optionally greater than 30 mm.sup.2. The second elements 5, according to a cross-section transversal to their prevalent development direction, exhibit an area greater than 3 mm.sup.2, optionally greater than 4 mm.sup.2. The second elements 5 are thinned by the stretching process by which a reduction of the cross-section area and a longitudinal elongation of the second elements 5 are obtained.

(38) The reticular structure 3 exhibits also a determined size, or thickness S, normal to the first and second elements, providing the reticular structure 3 with a three-dimensional structure certainly different from the one of a sheet material. Particularly, the maximum thickness S of the reticular structure 3 is greater than 3 mm, for example 4 or 5 mm. The thickness S is defined by the maximum distance between opposite sides of the reticular structure 3.

(39) The stretching process of the reticular structure 3 enables to improve the mechanical properties thereof, and particularly a greater tensile strength than the woven, metal or plastic unstretched geo-grids. Specifically, the reticular structure 3, as said before, is made of a plastic material, exhibits an areal mass (weight by surface unit) from 200 to 1200 g/m.sup.2. With reference to the mechanical characteristics, the reticular structure 3 exhibits a specific tensile strength, along the stretched elements and, particularly, along the second elements 5, greater than 20 kN/m, particularly comprised between 20 and 250 kN/m, optionally between 60 and 200 kN/m. The specific tensile strength is measured by the method set out in the EN ISO 10319 standard. Another mechanical parameter characterizing the reticular structure 3 is the 2% elongation strength greater than 7 kN/m, particularly comprised between 10 and 100 kN/m, optionally between 10 and 70 kN/m.

(40) As hereinbefore briefly described, the reticular structure 3 is partially integrated inside the facing body 2. Particularly, as it is visible in the attached figured, the reticular structure 3 comprises at least one first portion 3a integrated and stably embedded in the facing body 2 and one second portion 3b integrally joined to the first portion 3a, emerging from the inner face 2a of the facing body 2. The first portion 3a of the reticular structure 3 comprises a first and second flaps 8, 9 (FIG. 3A) spaced from each other and ending at the inner face 2a of the facing body 2. The second portion 3b of the reticular structure 3 exhibits also a first and second flaps 10, 11 (FIG. 3A) spaced from each other and integrally joined to the respective first and second flaps 8, 9 of the first portion 3a of the reticular structure 3. As it is visible in FIG. 12A for example, the containing body 2 can incorporate shielding elements 25, of plastic or rubber material, placed at the inner face 2a; the shielding elements 25 are configured for at least partially wrapping the first and second flaps 8, 9 of the reticular structure 3 for preventing this latter to be damaged due to the movements of the second portion 3b.

(41) The second portion 3b of the reticular structure 3 defines a plurality of slots 13, each of them, cooperatively with the inner face 2a of the containing body 2, substantially defines a closed outline loop. The plurality of slots 13 of the second portion 3b of the reticular structure 3 are aligned along a predetermined rectilinear direction D, for example parallel to a prevalent development plane of the facing body 2. Particularly, in an operative condition of the containing element, the direction D aligning the plurality of slots 13 is substantially horizontal (FIG. 2). The attached figures illustrate, in a non limiting way, the containing elements 1 provided with second portions 3b emerging from the facing body 2: each portion defines a plurality of slots 13. Therefore, there are, on each panel, two pluralities of slots 13 and therefore two closed loops (see FIGS. 3, 4 and 6 for example). As it is visible from the cross-section views in FIGS. 3, 4, 7-12, the reticular structure 3 comprises a single net or geo-grid folded inside the facing body 2 and exhibitingfor the same nettwo second portions 3b. In such condition, the reticular structure 3 extends along the facing body 2 between the different portions 3b.

(42) More particularly, FIGS. 3 and 4 illustrate a configuration of the reticular structure 3 positioned in the body 2 according to only one layer, particularly engaged above the reinforcement 12. FIG. 7 illustrates another configuration of the element 1 wherein the reticular structure 3 is placed in the body 2 along two layers: a first layer arranged between the reinforcement and the inner face 2a and a second layer arranged between the reinforcement 12 and the outer face 2b. De facto, in the configuration of FIG. 7, the reinforcement 12 is interposed between the first and second layers of the reticular structure 3. Instead, FIG. 8 illustrates a configuration of the containing element 1 wherein the reticular structure 3 exhibits two layers integrated in the body 2, both interposed between the reinforcement 12 and the outer face 2b. On the contrary, in FIG. 9, the reticular structure 3 is always present inside the body 2 always as a double layer but interposed between the reinforcement 12 and the inner face 2a of the body 2. Instead, FIGS. from 10 to 12 illustrate several configurations of the reticular structure 3, present inside the body 2 with a first layer developing between the portions 3b and a second layer developing only for a segment of the body 2. As it is specifically visible in FIGS. 3A, 4A, 7A and 9A, the reticular structure 3 in a non limiting way, is fixed also to the reinforcement 12 by means of anchoring elements 24. De facto, these elements are used during the step of making the body 2, for stably anchoring the reticular structure 3 to the reinforcement 12 (the structure and function of the anchoring elements 24 will be fully described in the following during the description of the process of making the containing element 1). Obviously, it is possible to provide on each facing body 2, just one plurality of slots 13 (only one loop) or a number of second portions 3b emerging from the body 2 greater than two (these conditions are not shown in the accompanying figures). Moreover, in a further variant of the embodiment not illustrated in the accompanying figures, it is present a single and distinct reticular structure 3 defining only one first portion 3a and only one portion 3b. In such configuration, the presence of two or more portions 3a, 3b is determined by the presence of two or more reticular structures 3 distinct from each other.

(43) Now, by analyzing the structure of each single slot 13, it is possible to observe (FIG. 6) that this latter exhibits a substantially C or U shape having a concavity facing the inner face 2a of the facing body 2; particularly, each slot 13 of the second portion 3b of the reticular structure 3 is integral with the facing body 2 and defines, with the inner face 2a of this latter, a closed loop. As hereinbefore described, the reticular structure 3 comprises the first and second elements 4, 5 (optionally is only formed by said first and second elements). The first elements 4 extend along respective prevalent development directions parallel to the direction D aligning the slots 13, particularly parallel to the prevalent development plane (extension plane) of the facing body 2. Viceversa, at least the second elements 5 of the second portion 3b of the reticular structure 3 extend along arc-shaped paths transversal to the prevalent development plane of the facing body 2. De facto, the second elements 5 of the reticular structure 3 exhibit paths transversaloptionally normalto the direction D aligning the slots 13, but only the second elements 5 of the second portion 3b exhibit paths transversal to the development plane (extension) of the facing body 2. The second portion 3b of the reticular structure 3 comprises at least one plurality of second elements 5 emerging from the inner face 2a of the facing body 2, each of them defines a slot 13: the plurality of second elements 5 is aligned along the predetermined rectilinear direction D parallel to the prevalent development plane of the facing body 2 itself. The second portion 3b can comprise first and second elements 4, 5 (FIG. 12A) or can be only formed by second elements 5; in this latter case, the second portion 3b of the reticular structure 3 is devoid of the first elements 4 which are all completely embedded in the facing body 2. From the dimensional point of view, the slots 13 of a same plurality (slots aligned along a same direction D) are positioned at a distance present between second elements 5; particularly, two consecutive slots 13 along the same direction D exhibit a minimum distance from each otherthe distance measured along the same direction Dless than 60 mm, particularly comprised between 10 and 50 mm, still more particularly comprised between 15 and 30 mm. The plurality of slots 13 therefore defines, along the predetermined direction D, a type of channel longitudinally delimited by opposite terminal slots 13: the channel exhibits a defined length from the measured maximum distance between said opposite terminal slots 13, greater than 0.5 m, particularly comprised between 0.7 and 2 m. In other words, the second portion 3b of the reticular structure 3 comprises, for each linear meter measured along the predetermined direction D, a number of slots 13 (and therefore of second elements 5) greater than 10, particularly comprised between 20 and 100, still more particularly comprised between 30 and 70. Generally, for each facing body 2, there are a number of slots 13 aligned along one single direction D greater than 20, particularly comprised between 50 and 300. More particularly, each single element 5, defining the second portion 3b of the reticular structure 3, defines a slot 13 the perimetral extension thereof is comprised between 50 and 500 mm, particularly between 80 and 300 mm (the perimetral extension of the slot between the first and second flaps 10, 11). In other words, each closed outline loop, defined by the cooperation of a slot 13 and the inner face 2b of the facing body 2, defines a passage inner area comprised between 8 and 800 cm.sup.2, particularly comprised between 20 and 300 cm.sup.2.

(44) Reinforced Ground Structure

(45) Further, it is an object of the present invention a reinforcement structure 100, particularly used for defining vertically extending supporting faces and/or walls. As it is visible in FIG. 1, the structure 100 comprises a plurality of containing elements 1 according to the present invention. The plurality of containing elements 1, in an operative condition of the structure 100, is vertically positioned by overlapped rows; particularly, there are a plurality of horizontal rows and a plurality of columns of side-by-side containing elements 1 in order to define substantially a wall containing the ground. Each of said containing element 1 exhibits at least one second portion 3a of the reticular structure 3 emerging from the inner face 2a of the facing body 2 in order to define a plurality of slots 13. More particularly, all the containing elements 1 exhibit second portions 3b emerging from the same side of the structure 100 (of the wall): all the containing elements 1 exhibit the second portions 3b emerging towards the ground to be reinforced and contained.

(46) As it is for example visible in FIGS. 1 and 2, the structure 100 comprises a predetermined number of reinforcement nets or geo-grids 14, each of them exhibits a monolithic structure of plastic material. In a preferred but non limiting embodiment of the invention, the net 14 exhibits substantially the same structure as the geo-grids 14. Particularly, the first elements 4 of the reticular structure 3 are substantially identical to the first elements 15 of the net 14, while the second elements 5 of the reticular structure are substantially identical to the second elements 16 of the net 14.

(47) Particularly, as it is visible in FIG. 2A, the net 14 also comprises a plurality of first elements 15 spaced from each other and developing along prevalent development paths and a plurality of second elements 16 also spaced from each other, which extend along respective prevalent development paths in a direction substantially transversal to the first elements 15; the first and second elements 15, 16 intersect each other at respective nodes 17 in order to form meshes 18. Specifically, the reinforcement net 14 substantially defines an integral reticular grid (in other words a monolithic grid integrally obtained and not made of connections obtained by gluing or weaving different elongated elements) of plastic material, comprising a series of first elements 15 parallel to each other; the first elements 15 are spaced from each other and interconnected by a plurality of second transversal elements 16, which are also for example parallel to each other. The elements 15 and 16 can be made of plastic materials selected on their physical and mechanical properties; for example, the elements 15 and 16 can be made of HDPE, PE, LDPE, PP, PVC, PS or other polymers.

(48) In the present discussion, it is understood that each of the first elements 15 extends along all the width of the net 14, in other words is formed by the plurality of portions aligned along a same line transversal to the reinforcement net 14. Similarly, each of the second elements 16 extends in the direction of the net 14 length, in other words is formed by the plurality of portions aligned along a same longitudinal line of the net 14: in this way, each of the first elements 15 is intersected by a plurality of second elements 16, while each of the second elements 16 is intersected by a plurality of first elements 15.

(49) Advantageously, the second elements 16 are stretched along their prevalent development direction (as it will be better described in the following, the second elements 16 are stretched after being formed) and exhibit a structure having molecular chains oriented along such stretching direction. The stretching action provides the second elements 16 with an elongated shape which consequently is capable of providing the net 14 with an optimal flexural strength, particularly enables the net 14 to freely bend along at least one axis transversal, substantially parallel, to the first elements 15.

(50) Particularly, the second elements 16 exhibit a stretching ratio greater than 3, optionally comprised between 3 and 8, more optionally between 4 and 7; the stretching ratio of the second elements 15 is defined as a ratio of a final length of the second elements 15 after being stretched, to an initial length of the second elements 15 before being stretched (in other words after forming the reticular structure 3 but before stretching it). According to the stretching rate, the second elements 16 exhibit a more or less thin structure, which enables also to have a thread-like shape; anyway, the second elements 15 exhibit a cross-section which, at a median point between two first consecutive elements 15, is substantially less than the cross-section of said first elements 15.

(51) Each of these first and second elements 15, 16 exhibit portions extending between consecutive nodes 17. Moreover, due to the stretching step of the second element 16, these latter exhibit portionsextending between consecutive nodes 17having terminal areas of a cross-section (measured normal to the main development direction of the second elements 16) progressively decreasing from a node 17 towards a centre line of the portions, and a central area having a substantially constant cross-section. On the contrary, with reference to the first elements 15, these latter, in a first embodiment, exhibit, in a non limiting way, a substantially unstretched structure (or at most slightly stretched) and a thickness (and a cross-section) constantly greater than the thickness (and than the cross-section) of the second elements 16. In such configuration, the first elements 15 substantially define more compression-resistant bars capable of having a greater friction against the ground than the second elements 16. The first elements are maintained unstretched because the net 14 must have a determined stiffness and a good ground anchoring capacity.

(52) In a second embodiment, the first elements 15 are also stretched along their development in order to define in this way a bi-layered reticular structure. Despite the reticular structure can exhibit a substantially bi-layered structure, it is anyway preferable to make different the stretch of the first and second elements. Particularly, the stretching ratio of the first elements 15 is at least half the stretching ratio of the second elements 16. In this way it is possible to obtain first elements having an oriented molecular structure and therefore improved from a tensile strength point of view but anyway having a stiffer structure than the second elements 16. Specifically, it is preferable the first elements 15 maintain a determined stiffness and a determined bar shape (not a thread-like shape) so that the same can provide a determined grip (anchoring) with the ground. Therefore, in a preferred but non limiting embodiment of the invention, the first elements 15 are not stretched or are slightly stretched: for example, they are stretched so that the stretching ratio is not greater than 1.5, particularly is about 1.25.

(53) Now, by specifically analyzing the net 14 structure from the dimensional point of view, it is possible to define the distances between the first and second elements 15, 16. Particularly, the distance between two first adjacent elements 15 is comprised between 100 mm and 400 mm, optionally between 200 mm and 300 mm. The overall length of each first element 15 of the net 14 is slightly smaller than the body 2 (panel) length and is particularly greater than 0.5 m, specifically comprised between 0.7 and 2.5 m, still more particularly comprised between 0.7 and 2 m. The distance between second adjacent elements 16 is comprised between 10 mm and 50 mm, optionally between 20 mm and 40 mm. As this distance changes, also the dimensions of the meshes 18 change, which can exhibit a through area comprised between 1000 and 20000 mm.sup.2. Further, the first elements 15, according to a cross-section transversal to their prevalent development direction, exhibit an area greater than 15 mm.sup.2, optionally greater than 30 mm.sup.2. The second elements 16, along a cross-section transversal to their prevalent development direction, exhibit an area greater than 3 mm.sup.2, optionally greater than 4 mm.sup.2. The second elements 16 are thinned by the stretching process by which it is obtained a reduction of the cross-section area and a longitudinal elongation of the second elements 16. The net 14 exhibits also a determined size, or thickness S, normal to the first and second elements, providing the net 14 with a three-dimensional structure definitely different from the sheet materials. Particularly, the maximum thickness S of the net 14 is greater than 3 mm, for example 4 or 5 mm. The thickness S is defined by the maximum distance between opposite sides of the net 14. The net 14 stretching process enables to improve the mechanical properties, and particularly a better tensile strength than the woven, metallic, or plastic unstretched geo-grids. Specifically, the net 14, as hereinbefore said, is made of a plastic material, exhibits an areal mass (weight by surface unit) from 200 to 1200 g/m.sup.2. With reference to the mechanical properties, the net 14 exhibits a specific tensile strength, along the stretched elements and particularly along the second elements 16, greater than 20 kN/m, particularly comprised between 20 and 250 kN/m, optionally between 60 and 200 kN/m. The specific tensile strength is measured by the method set out in the EN ISO 10319 standard. Another mechanical parameter characterizing the net 14 is the 2% elongation strength, greater than 7 kN/m, particularly comprised between 10 and 100 kN/m, optionally between 10 and 70 kN/m.

(54) As it is for example visible in FIG. 2A, the net 14 is engaged at least with a plurality of slots 14 aligned along the same direction D; particularly, at least a series of second elements 16 of said net 14, comprised between two first adjacent immediately consecutive elements 15, are inserted and interwoven with a plurality of slots 13 of the containing element 1 in order to form with these latter a closed loop. Further, the structure 100 comprises at least one locking bar 19 (FIG. 2A) engaged inside the plurality of slots 13 so that the series of second elements 16 of the net 14 is interposed between the facing body 2 and locking bar 19: the locking bar 19 is configured for stably constraining the facing net 14 to the containing element 1. Specifically and as it is visible in FIG. 2, each containing element 1 exhibiting at least one second portion 3b emerging from the body 2 and therefore defining at least one plurality of slots 13, is constrained to a reinforcement net 14: the net 14 extends from the facing body 2 inside the ground for defining a type of reinforcement for the same and therefore for reinforcing it. As hereinbefore described, the net 14 comprises a series of first and second elements 15, 16; the net 14 is engaged with a containing element 1 so that the first elements 4 of this latter are substantially parallelly to the first elements of the net 14. In other words, the first elements 15 of the net 14 extend along the prevalent development directions substantially parallelly to the prevalent development plane of the facing body 2. In an operative condition of the structure 100, the prevalent development direction of each first element 15 of the net 14 is substantially horizontal. Referring to the second elements 16 of the net 14, these latter extend along paths transversal, particularly normal, to the directions of the first elements 15. Engaging the reinforcement net 14 with the reticular structure 3 of the containing element 1 is obtained by inserting and therefore interweaving one or more portions of the second elements 16comprised between two immediately consecutive first adjacent elements 15with a plurality of slots 13 of a second portion 3b. Each of the second elements 16 inserted in the slots 13 defines, with at least one second element 5 of the reticular structure 3 (of the second portion 3b) a closed outline loop receiving the locking element 19. De facto, the locking element is interposed between a second element 5 of the second portion 3b and a second element 16 of the reinforcement net 14: the locking bar 19 prevents the reinforcement net 14 from exiting the plurality of slots 13.

(55) The reinforcement net 14 exhibits at least one portion arranged in a horizontal position inside the ground at the level of a plurality of aligned slots 13: a terminal portion of the net 14 is interwoven and constrained to a plurality of slots so that is integral with the facing body 2.

(56) However, in a preferred but non limiting configuration of the invention, the net 14 defines plural layers exhibiting, according to a cross-section of the structure itself, a substantially two-dimensional development. Specifically, the reinforcement net 14 comprises at least one first and one second rectilinear segments 21, 22 (two segments), spaced from each other and positioned transversally, particularly normal, to the prevalent development plane of the facing body 2; the reinforcement net 14 further comprises at least one connecting segment 23 interposed between the first and second rectilinear segments 21, 22 and integrally joined to these latter: the connecting segment 23 extends parallelly to the inner face 2a of one or more facing bodies 2. De facto, in this two-dimensional configuration, the reinforcement net 14 defines, along a cross-section, a substantially C shape having a concavity facing away from the facing bodies 2. In this configuration, the reinforcement net 14 is interwoven and therefore is engagedby means of respective locking bars 19with two or more rows of slots 13 distinct and spaced from each other. Particularly, as it is visible for example in FIG. 6A, the connecting segment 23 of the reinforcement net 14 is integrally joined to two rectilinear segments (the first and second segments 21 and 22) by respective joining portions, each of them is interwoven with a plurality of slots 13 aligned along a same direction D: the locking bar 19 is interposed between a joining portion of the reinforcement net 14 and a plurality of slots 13 of one or more reticular structures 3. The joining portions represent actually net portions 14 radiused and inserted inside the plurality of slots 13. Providing a reinforcement net 14 according to a multilayer configuration, enables the same to be constrained to one or more pluralities of slots at different levels (see FIGS. 2 and 6A, for example). This enables the net 14 to be constrained to a plurality of slots 13 of the same facing body 2 or to constrain two different pluralities of slots of distinct facing bodies. This latter configuration is schematically illustrated in FIG. 6A wherein the same reinforcement net 14 is constrained below a plurality of slots 13 of a first underlying facing body 2 and, at the same time, to a plurality of slots 13 of an immediately adjacent second facing body 2 placed above the first body 2: the first net 14 segment emerges from the first underlying facing body 2, while the second segment 22 emerges from the upper facing body 2. The connecting portion or segment 23 of the reinforcement net 14 extends parallelly to both the facing bodies 2 and defines a connection between these latter.

(57) It is useful to note that the geo-grids (the net 14 and the reticular structure 3) are coupled by means of the second stretched elements 5, 16 which exhibit a high tensile strength adapted to provide the geo-grids with an effective coupling.

(58) Process of Making a Containing Element 1

(59) Further, it is an object of the present invention a process of making a containing element 1 according to the present invention and particularly according to the present description and the attached claims. First of all, the process comprises a step of providing the reticular structure 3; this latter can be obtained by an extruded (or calendered, laminated or moulded) plate preform and then perforated (with dead holes or through holes). Alternatively, the reticular structure 3 can be made of a preform obtained by extruding precursors of the first elements 4 and simultaneously by forming precursors of the second elements 5 placed transversal to the precursors of the first elements. In the first case (perforated plate) it is obtained a preform having a constant thickness except obviously for the perforated areas, while in the second case it is obtained an artifact having a varying thickness. In case of a preform defined by a plate, the process will comprise at least one step of extruding the plate along an advancing direction and, immediately after forming the plate, a step of perforating the same for defining a flat perforated preform. After forming the perforated plate, this latter is stretched along the advancement direction of the same and/or transversally to the advancement direction. The first elements are formed so that the prevalent development direction of the same is normal to the advancement direction (advancement direction of the reticular structure). The stretching ratio is defined by the length of the elements (first and/or second elements) defining the preform to the length of the same at the end of the process immediately after being stretched. When the reticular structure is extruded, the first and second elements 4, 5 are made by a simultaneous extrusion process. For example, the plastic material is supplied by a hopper and then is delivered towards an extrusion head. At the extrusion head, the first elements 4 (or the precursors of the same elements) are extruded and the precursors of the second elements are co-extruded transversally to the first elements in order to form an integral reticular and tubular body exiting the extrusion head: the so formed body therefore is an integral monolithic plastic body.

(60) After, there is a longitudinal cutting station which forms a reticular structural preform having the precursors of the first elements and precursors of the second elements: the precursors of the first elements develop, in a non limiting way, parallelly to an advancement direction of the reticular structure (the advancement direction of the co-extrusion process). Alternatively, it is possible to define precursors of the first elements transversally to the advancement direction of the reticular structure (transversally to the advancement direction of the co-extrusion process).

(61) After forming the reticular structure preform, this latter is stretched transversally and/or parallelly to the reticular structure advancement direction in order to form said stretched reticular structure 3. The stretching step is performed immediately after forming and joining the precursors of the first and second elements (forming an unstretched net).

(62) As hereinbefore described, the stretching step enables the reticular structure 3 to increase its tensile strength by increasing the temperature of the reticular structure 3 to more than 80 C., and then gripping the reticular structure itself for stretching it at least along the development of the second elements 5. The reticular structure 3 is taken to the stretching temperature by a hot air convection heating process or by hot water baths or by other heating systems.

(63) By means of the described process, the first elements 4 positioned at a distance varying as a function of the pulsing frequency of the extrusion head (or perforation frequency when the starting material is a plate) and as a function of the longitudinally applied stretching ratio are obtained, while the second elements 5 are spaced from each other as a function of the pre-selected configuration for the extrusion head (or as a function of the distance between the punches in case the starting material is a plate), so that it is obtained a dimension of the meshes, varying according to the requirements and during the same manufacturing process. After, the reticular structure 3 is cut at a predetermined length, measured along the first or second elements.

(64) After providing the reticular structure 3, this latter is positioned inside a formwork 20 (FIG. 25) which, as it will be better described in the following, is used for forming the facing body 2. The reticular structure 3 is placed inside the formwork 20 and is folded, particularly folded one or more times along a folding direction parallel to the prevalent development direction of the first elements 4. Folding the reticular structure 3 defines at least a plurality of slots 13.

(65) Further, the process can comprise, before positioning the reticular structure 3 in the formwork 20, providing at least one reinforcement 12 and positioning the same inside the formwork 20. After positioning the reinforcement 12, the process provides to position the reticular structure 3 in the formwork 20 on the reinforcement and/or inside this latter. De facto, the reinforcement 12 can be used for correctly positioning the reticular structure 3. Actually, the reticular structure 3 can be stably constrained to the reinforcement 12, for example by bands and/or similar elements, for enabling the structure itself to maintain a determined configuration, for example constraining the structure 3 to the reinforcement can help the structure 3 maintaining a folded configuration for defining said slots 13.

(66) After positioning the reticular structure 3, and possibly the reinforcement 12, inside the formwork 20, the process provides to pour a predetermined quantity of a cementitious material, for example concrete, at least partially at a liquid state, inside the formwork 20. The step of pouring the predetermined quantity of material inside the formwork 20 enables to fill this latter to a predetermined level defining the inner face 2a of the facing body 2 and above which the plurality of slots 13 of the reticular structure 3 at least partially emerge. For obtaining the final facing body 2, it will be necessary to wait the hardening of the cementitious material inside the formwork 20: as hereinbefore described, part of the reticular structure 3 is embedded inside the facing body 2. It is useful to specify that providing the reticular structure 3, and pouring the predetermined quantity of cementitious material, enables to obtain the second portion 3b of the reticular structure. De facto, based on how much the reticular structure 3 has been folded and based on the quantity of material poured in the formwork 20, it is possible to define slots 13 having different size (actually it is possible to define the through area of the slots 13). The step of providing the reticular structure 3 enables to give to each slot a substantially C or U shape having a concavity facing the inner face 2a of the facing body 2; each slot 13 of the second portion 3b of the reticular structure 3 is integral with the facing body 2 and defines with the inner face 2a of this latter a closed outline loop. The step of providing the reticular structure 3 enables to define, for this latter, at least the following portions: at least the first portion 3a exhibiting at least one first and one second flaps 8, 9 spaced from each other, embedded in the facing body 2 and ending at the inner face 2a of this latter, at least one second portion 3b exhibiting also a first and second flaps 10, 11 spaced from each other and integrally joined to the respective first and second flaps 8, 9 of the first portion 3a of the reticular structure 3.

(67) FIGS. from 24 to 26 schematically illustrate the steps of providing a containing element 1 which comprises two portions 3b and a reinforcement 12. However, it is possible to provide containing elements as hereinbefore described and therefore having also only one portion 3b or more than two portions 3b. Further, it is possible to provide containing elements 1 without the reinforcement 12.

(68) Process of Making Reinforced Ground Structures

(69) Moreover, it is on object of the present invention a process of making a reinforced ground structure 100 according to the present invention, and particularly according to the previous description and attached claims.

(70) The process comprises providing a plurality of containing elements 1 and providing a plurality of reinforcement nets 14. The reinforcement net 14 can be made by one of the described manufacturing processes of making the reticular structure 3. First of all, the process comprises finding the installation site and then escavating to a foundation depth (the minimum depth is 50 cm under the P.C.) and eventually reclaiming the underlying ground, according to the design specifications. Afterwards, the process provides the plano-altimetric tracing of the work by topographic measurements. Then, it is provided a step of pouring a predetermined quantity of cementitious material (for example concrete) for forming a base boot (non reinforced lower boot); the boot does not have a structural function but is used for enabling to correctly and efficiently position the containing element 1.

(71) Then, the process provides to position a series of containing element 1 aligned along a predetermined path in order to form a type of wall wherein the inner faces 2a of the respective facing bodies 2 are all facing a same side. Particularly, the process comprises providing a plurality of containing elements 1 in order to define a plurality of horizontal rows of vertically overlapped containing elements 1. Based on the desired height to be obtained, two or more overlapped horizontal rows are provided. FIG. 23 illustrates, in a non limiting way, a configuration of a structure 100 exhibiting four rows of overlapped containing elements 1. Advantageously, the facing bodies 2 can comprise lateral guides configured for helping to position the bodies 2 themselves and facilitating their support: the guides are configured for enabling to anchor a facing body 2 to a flanked body.

(72) After positioning the containing elements 1, the process provides to lay a first ground layer and compacting it in order to arrive at a first series of slots 13 of a containing element 1. Once arrived at a first series of slots 13, the reinforcement net 14 is positioned. Particularly, the process comprises laying at least one reinforcement net 14 at a plurality of slots 13 (above the first ground layer): the reinforcement net 14 extending from said plurality of slots 13 of a facing body 2 away from this latter in a rectilinear direction, particularly horizontal, in order to define a first segment 21. The first segment extends above the first ground layer.

(73) Afterwards, at least one portion of said reinforcement net 14 is inserted in said plurality of slots 13; actually, a portion of the net 14 is interwoven with the slots 13 so that these can define a series of closed loops.

(74) Successively, the process provides to engage at least one locking bar 19 between said plurality of slots 13 and the portion of the reinforcement net 14 inserted in this latter (the bar is inserted in the series of closed loops): the locking bar 19 being interposed between the plurality of slots 13 and reinforcement net 14 for stably constraining them. The net 14 can comprise the provision of only one segment 21 or, as hereinbefore described, can provide the segments 21, 22 and 23 (a two-dimensional net having a substantially C shape). In case the net is configured by several layers (C two-dimensional net), laying the net 14 provides to lay the first segment 21 on the first ground layer and lay the connecting segment 23 parallelly to the body 2. After laying the first segment 2 and possibly the connecting segment 23, the process provides to lay and compact a second ground layer on the first segment 21 until a further plurality of slots 13 is reached.

(75) After providing the second ground layer, the process provides to lay a further net 14 portion on the second ground layer; the further net portion is then engaged with the further plurality of slots 13 by at least one locking bar 19 as hereinbefore described. In case the net exhibits the connecting element 23, the provision of the further net 14 provides to turn the same over the second ground layer: in this way it is defined the second segment 22. The second ground layer is therefore interposed between the first and second segments 21, 22. Therefore it is possible to repeat the above described steps for forming a plurality of ground layers and therefore arriving to an height such to cover the overall surface of the facing bodies 2.

Advantages of the Invention

(76) Thanks to the invention, it is possible to obtain a containing element 1 and an associated reinforced ground structure 100 capable to effectively meet plural applications.

(77) A substantial advantage is associated to the use of a plastic reticular structure 3 partially embedded in the facing body 2 and adapted to define a plurality of slots 13 to be anchored to the ground reinforcement elements. Using a plastic material reticular structure or net 3 prevents this latter from being subjected to corrosion/oxidation by the ground and therefore from damaging the net structure. Therefore, the reticular structure is adapted to define an effective and durable system with the time. Moreover, stretching the reticular structure 3 and using this latter for defining the slots 13 enable the reticular structure 3 to define strong and effective anchorings. De facto, the distinctive shape of the slots 13 of the portion 3b enables the containing element 1 to be easily constrained to outer reinforcement elements (to the net 14, for example) by only using the high tensile strength of the stretched elements (of the second elements 5 defining the second portion 3b, for example) without excessively loading the weak points of the structure 3, in other words the nodes 6. FIGS. from 16 to 18 illustrate a known connecting system defined between facing bodies and plastic nets. From these figures, it is apparent the structure of these systems and the associated disadvantages. Actually, contrary to what the Applicant has provided, the facing bodies exhibit nets partially integrated in the body, and defining rectilinear bands emerging from the body itself; a further ground reinforcement net is interwoven with the rectilinear band and is constrained to this latter by means of a bar. Once the nets are stretched, these, in contrast with what the Applicant has provided, concentrate the stresses just at the nodes, and consequently at the weaker/more fragile points of the nets. Often, for this reason, in the reinforced ground structures known to date, the reticular structure and/or reinforcement net are subjected to serious damages or even breaks compromising the reinforcement of the ground. A further advantage attributable to the configuration of the portion 3b of the reticular structure 3, is represented by the possibility of evenly distributing the stresses on the facing body 2. This enables to use facing bodies 2 of a small thickness and use locking bars of plastic material having also a small cross-section. De facto, the presence of a high number of second elements 5 enables the second portion 3b to evenly distribute the traction generated by the net 14. Evenly distributing the stresses enables to adequately size all the elements helping containing the ground, such as for example the locking bar 18 and net 14. In addition, by combining the reticular structure 3 (anchoring the facing body 2) with the plastic material reinforcement nets 14, it is possible to obtain an effective ground reinforcement. Moreover, the mono-oriented geo-grids or nets 14 (mono-stretched or substantially mono-stretched) having an integral junction as hereinbefore described, are reinforcing elements with a high module of elasticity and high strength of the junctions. The net 14 structure enables both to anchor the face and reinforce the ground from the inside in an uniform way, reducing in this way the thrust of the ground against the facing body 2 with a more effective action than the one provided by the anchoring systems formed by discrete strips or bars. Using geo-grids as reinforcement elements enables to evenly reinforce the ground from the inside and with a more effective action than the one provided by the anchoring systems formed by discrete strips or bands: the presence of the first elements 5 parallel to the facing wall, provides the net with a correct anchoring to the ground, while the second stretched elements 16 provide a high tensile strength and therefore they are more resistant to the thrust of the ground against the facing body 2 (the resistance to the extraction of the reinforcement 14 from the ground is greater). The above described characteristics enable to obtain the following advantages: a cost reduction in comparison with the preceding approaches using metal anchoring systems having a cost certainly higher than the one of the approach completely made of plastic of the Applicant; there is no limit in height. The high strength of the containing element 1 enables the structure 100 to develop to very high vertical extensions; an extremely durable system. The parts contacting the ground are made of plastic and concrete and therefore are not subjected to the ground corrosive/oxidating actions; it does not require any maintenance. The effective constrain and strength with time of the nets (reticular structure 3 and reinforcement net 14) prevents to implement processes for maintaining the containing elements 1 and/or nets 14; the constrain between the facing bodies 2 is increased. The reticular structure 3 and net 14 enable to generate strong links between adjacent bodies, making them integral to each other; the system has an easier and speedier implementation. The step of laying only one carpet of nets 14 is certainly speedier and simpler than a system that comprises providing and engaging single bands and/or strips; the quantity of material for the nets 14, required for obtaining a determined strength, is certainly reduced with respect to the material required by a bands or strips system; the quantitative and economical effect of the net 14 reinforcement, being equal to the laid vertical facing surface, is smaller.