FR2708969A1 - Method of producing civil engineering works and resulting work - Google Patents

Abstract

The invention relates to a method for producing civil engineering structures and in particular underground structures. It consists in stably erecting at least one section of three-dimensional monolithic metal reinforcement (1) to be projected in a confined manner onto said reinforcement (1), a concrete (102) with rapid setting and hardening, starting with the lower parts of the section and going up towards the upper parts to form progressively and without breaking the stability, a self-supporting structure with thin wall and substantially uniform thickness in which said reinforcement (1) is at least partially embedded.

Description

Method of producing civil engineering works and structure obtained
The present invention relates to a method of making civil engineering works including underground works such as tunnels and the structure or structure thus obtained.

 There are already methods of coating and retaining the tunnel vaults according to which is built in the excavation an internal structure from prefabricated sections of reinforced concrete interconnected by fasteners. However, these fasteners are zones of weakening of the structure which in itself is not very resistant to shocks.

 According to another method, a concrete-reinforced coating is applied directly to the vault of the excavation, but an irregular jig is then obtained. In addition, the anchoring of the coating in the vault remains fragile which poses security problems.

 Yet another method is to have in the excavation panels on a heterolithic metal frame and then projecting concrete against said panels to hang and drown the framework in the concrete. However, ordinary concretes do not allow an immediate catch which poses problems of stability and holding especially in overhanging areas. In addition, the framework does not have a regular and homogeneous metal network, which poses problems of mechanical strength for the structure.

 The present invention aims to solve the above technical problems satisfactorily.

 This object is achieved in accordance with the invention by means of a method for producing civil engineering works and in particular underground works, characterized in that it consists of stably raising at least one section of metal reinforcement. monolithic three-dimensional projecting confined on said frame, a concrete quick setting and curing, by emitting by the lower parts of the section and upward towards the high parts to form gradually and without breaking the stability a self-supporting wall structure thin and substantially uniform thickness in which is at least partially embedded said armature.

 According to an advantageous characteristic, said armature section is raised so as to define an upper or upper surface and a lower face or lower surface.

 According to another feature, there is fixed on the extrados an envelope for confining the shotcrete between the intrados and the extrados. This envelope is optionally made of a waterproof sheet and / or insulating.

 According to a first embodiment, said structure is produced in situ.

 According to another mode of implementation, the projection of the concrete is carried out dry with prior wetting of the concrete.

 According to an advantageous characteristic, the stability of the reinforcement section is ensured, in particular by means of stiffening elements consisting, on the one hand, in the curvature of the section of microcintres comprising small diameter steel bars placed in compression by means of post -compression and, secondly, in the perpendicular direction of small diameter steel bars integrated in the thickness of the frame.

 Said concrete used in projection comprises a hydraulic binder containing from 50 to 99% of a natural cement resulting from the calcination at a temperature between 900 and 1200 ° C of a single raw material containing sulphured clay phases and carbonate calcium in an intimate mixture and from 1 to 50% of a pozzolanic product or acting as filler.

 According to an advantageous characteristic, said concrete comprises from 300 kg to 800 kg of hydraulic binder per cubic meter of concrete used.

 In addition, the water / hydraulic binder ratio of the concrete is between 0.25 and 0.50.

 The armature used has on its external faces frames parallel to each other and at heart inclined legs connecting these frames; said chords being oriented in the carrier direction.

 Preferably, in the armature, each node of each even-numbered chord defining a first face of the armature is in the form of a triangle and couples the adjacent ends of two legs respectively extending on both sides of the frame considered and in the same direction, the directions reversing for the jambs of the two consecutive members of even rank, and in that each node of each chord of odd rank defining the second face of the structure is shaped in parallelogram and couples the adjacent ends of two jambs extending respectively on both sides of the frame in question and in opposite directions, the directions reversing for homologous legs of two consecutive members of odd rank.

 Another object of the invention is a self-supporting structure for civil engineering works and in particular underground structures, characterized in that it comprises at least one section of three-dimensional monolithic metal reinforcement coated with a concrete comprising a binder. rapid setting and curing hydraulic system consisting of 50 to 99% of a natural cement resulting from the calcination at a temperature of 900 to 1200 ° C of a single raw material containing sulphurous clay phases and calcium carbonate in an intimate mixture and from 1 to 50% of a pozzolanic product or acting as filler.

 According to an advantageous characteristic, said armature has on its external faces frames parallel to each other and to the heart inclined legs connecting these frames.

 According to another characteristic, said chords are oriented in the carrier direction.

 According to yet another characteristic, said structure is shaped so as to define an upper or upper surface and a lower face or lower surface.

 Yet another object of the invention is a previously mentioned method of use for producing an internal structure for retaining and / or covering the vault of a tunnel.

 The method and the structure of the invention make it possible to solve in particular the safety problems posed by the falling of the stones coming from the vault of the excavation of a tunnel.

 The structure of the invention is simple and light. It is resistant to compression and shock. It can, by filling the space between the extrados and the vault, to oppose the fall of rubble or stones.

 The method of the invention uses only components ready for use and is quickly and simply implemented even under difficult working conditions (cold weather, dripping walls ...). It saves considerable time in the manufacture of underground structures. The structure obtained has a regular geometry and a uniform thickness. The surface aspect of the intrados is perfectly smooth and even.

 The self-supporting nature of the structure, even during its construction, makes it possible to envisage putting the tunnel into circulation immediately after concreting.

 The extrados can receive, in addition, an envelope of waterproof and insulating material without any drilling is necessary.

 In addition, it is not necessary to provide panels on the extrados for the chemical or mechanical attachment of shotcrete.

 The containment of the shotcrete may be provided by an envelope that serves only to stop the concrete and can be removed after concreting.

 Moreover, the costs of achieving the structure of the invention are significantly reduced compared to the structures produced by traditional methods. Because the implementation is faster. At the same time, the quantities of materials used are lower and the concrete losses are minimized.

 The method of the invention can be advantageously used for the realization or repair of underground structures, such as tunnels or hydraulic structures (collectors ...) to replace or in addition to existing structures.

 In some cases of cramped sites, the template of the structure of the invention allows to intervene while traditional methods are impossible or difficult to implement.

 The reinforcement used in the invention has on its external faces frames parallel to each other and at the heart of inclined legs connecting said chords. It must have a significant resistance, especially any crushing that tends to bring the plans of its frames. Its manufacture must also be feasible in series at a competitive cost price. More specifically, its cutting must be executable continuously by means of circular knives and its deployment must be feasible automatically, preferably continuously. Of course, the losses of metal must be excluded. In addition, it must be possible to insert longitudinally between the members and transversely between the legs reinforcing or stabilizing elements such as rods or servitude elements such as electrical cables, pipes, ducts, tie rods, etc.

 To achieve this goal, each node of each member of even rank defining a first face of the armature is shaped as a triangle and couples the adjacent ends of two legs respectively extending on both sides of the frame considered and in the same direction, the inverting directions for the legs of the two consecutive members of even rank, while each node of each chord of odd rank defining the second face of the armature is shaped in parallelogram and couples the adjacent ends of the two legs extending respectively from the two sides of the frame considered and in opposite directions, the directions reversing for homologous legs of two consecutive members of odd rank.

 More particularly, the connection nodes are arranged, on the undeployed metal, along lines perpendicular to the chords during deployment, if the parallelogram nodes of the odd-sized members are immobilized longitudinally, against the triangular nodes of each chord of even rank are moved longitudinally, sometimes in one direction, for a member of even rank considered, and sometimes in the opposite direction, for the two members of even rank consecutive thereto, so that the legs incline in the same direction. opponent for two consecutive members of even rank while the first face defined therefrom deviates from the second face defined by the members of odd rank.

 Preferably, during the deployment of the previously cut metal sheet, the ribs are spaced transversely from each other.

 More precisely, each parallelogram coupling node of a chord of odd rank is constituted by the part thereof on which end the two legs of opposite directions which are coupled thereto, and by the ends of these legs which are separated. those of the legs extending in extension by two cutting angles, which are parallel to each other and to the line connecting two diagonally opposite points of this part, the cutting angles of an odd-sized chord being inclined symmetrically with respect to each other; to those of the two consecutive members of odd rank.

 Each triangular coupling node of a chord of even rank is constituted by the part thereof on which end the two jambs of the same direction which are coupled thereto, as well as by the ends of these legs which are separated from those of jambs extending in extension by two cutting angles, which are respectively parallel to the two lines which diagonally connect the four points of this part, the cutting bias of a pair of even rank members converging opposite those of the two consecutive members of even rank.

 At the time of laying sections extending from each other and in contact by their extreme edges defined by the even end members of the first face and odd of the second face, the chords of each section cooperate with regularly spaced cross bars of which the ends are fixed, in particular by forced hooking, on the chords of two contiguous sections.

The invention will be better understood on reading the following description accompanied by the drawings in which:
Figure 1 is a partial plan view showing the pre-cut and undeployed metal used for the reinforcement of the invention;
Figure 2 is a plan view similar to Figure 1 showing the beginning of the deployment and to distinguish the various components of the frame or frame according to the invention;
FIG. 3 is a partial perspective illustrating this framework or frame deployed from the pre-cut metal according to FIGS. 1 and 2;
Figure 4 is a fragmentary partial plan view similar to Figure 1, but representing on a larger scale five successive nodes of the metal before deployment;
Figure 5 is a partial cross section showing the assembly of several sections together;
Figure 6 is an elevation taken along arrow F of Figure 5; and,
Figures 7a, 7b, 7c and 7d are perspective views of the implementation of the method of the invention.

 The metal sheet 5 (FIG. 1) intended for the manufacture of the frame 1 is preferably made of steel and it is precut to generate, during its deployment, the three-dimensional monolithic reinforcement 1 shown in FIG.

 As is apparent from FIGS. 1 to 4, the monolithic and three-dimensional reinforcement 1 has members parallel to one another and spaced apart from one another; these members are designated by the general reference 6 and are distinguished by an index defining their rank; it is important to note right now that the chords of odd rank 6.1, 6.3, 6.5, 6.7, 6.9 ..., 6.2n + 1 are intended to delimit one of the faces of the reinforcement, whereas the chords of rank pairs 6.2, 6.4, 6.6, 6.8 .., 6.2n are intended to delimit the opposite face of said armature.

 The ribs 6 are separated from each other by solid portions of the sheet 5, intended to constitute legs 57, 58, 67 and 68 ending on connecting nodes 59, 69, 79 and 89 of the frames 6.1, 6.5. .. 6.4n + 1; 6.3, 6.7 6.4n + 3; 6.4, 6.8 ... 6.4n; 6.2, 6.6 .... 6.4n + 2, respectively.

Considering the chords of odd rank 6.2n + 1 in Figure 2, the legs 57 extend above and to the right, while the legs 58 extend below and to the left, a leg 57 being conjugated to a leg 58 to end on a parallelogram-shaped node 59 of an odd-rank ribs 6.4n + 1, such as the chord 6.5, the legs 67 extend above and to the left, while the jambs 68 extend below and to the right, a leg 67 being conjugated to a leg 68 to terminate on a parallelogram-shaped node 69 of an odd-numbered rib member 6.4n + 3, such as the chord 6.3, the chords of odd rank 6.2n + I being alternatively provided with knots 59 with 57,58 legs and knots 69 with jambs 67, 68
Considering now the members of even rank 6.2n in FIG. 2, they are alternatively provided with:
triangular nodes 79 (chords 6.4n, such as chord 6.4) on which converge left upper and lower legs 67, 67,
triangular nodes 89 (chords 6.4n + 2, such as chord 6.2) on which converge from the right upper and lower legs 58 and 67.

 To obtain this particular arrangement of the chords 6, legs 57, 58, 67, 68 and nodes 59, 69, 79 and 89, each chord 6 is delimited by two interrupted cutting lines 50, 51 whose interruptions allow to remain solid parts which are precisely the aforementioned connection nodes. These lines 50, 51 separate the chords of the legs and are extended by cutting angles 52 to 55 which separate each leg from the one with which it is aligned before deployment and, at the same time, which delimit the parts of the nodes projecting laterally from the legs. frames.

Thus, each node in the form of a parallelogram 59, 4n + 1 is delimited by the cutting angles 52 and 53,
each node in the form of a parallelogram 69,4n + 3 is delimited by the cutting angles 54 and 55,
each triangular node 79, 4n is delimited by the cutting angles 52 and 55 common to neighboring nodes 59 and 69,
each triangular node 89, 4n + 2 is delimited by cutting angles 53 and 54 common to neighboring nodes 59 and 69.

 These cutting angles are oriented and distributed in a very particular way, analyzed in the following with reference to FIG. 4. The metal sheet 5 is divided into narrow strips by the cutting lines 50 and 51 which are interrupted in points 50a, 50b and respectively Sia, 51b aligned on fictitious lines 61a, 61b, these being perpendicular to the cutting lines 50, 51 and spaced in correspondence with the chosen size of the nodes (left half of Figure 4). Four neighboring points 50a, 50b, 51a and 51b could be connected by imaginary diagonals 62 and 63.

 As shown in the right half of FIG. 4, the aforesaid strips successively constitute the chord 6.1, the legs 58, the chord 6.2, the legs 67, the chord 6.3, the legs 68, the chord 6.4, the legs 57, the chord 6.5, legs 58, chord 6.6 and so on. In addition, the cutting bias 52 and 53 are parallel to the diagonal 69, while the cutting bias 54 and 55 are parallel to the conjugate diagonal 63; these biases are distributed to be successively parallel to each other by two and diverging from each other by two.

So, always referring to the right half of Figure 4:
the triangular node 89 is defined by two biases 53 and 54 converging to the left on the chord 6.2 and diverging to the right on two legs 58 and 67 framing this chord separated therefrom by the cutting lines 50 and 51 to the points 50b and 51b,
the parallelogram-shaped node 69 is defined by two parallel biasing means 54 and 55 tilting from the left upwards to the bottom right to connect legs 67 and 68 to the frame 6.3 beyond the interruption points 50a and 51b of the cutting lines 50 and 51 which separate this frame 6.3 said legs 67 and 68 extending from both sides in prolongation,
the triangular node 79 is defined by two biases 55 and 52 converging to the right on the frame 6.4 and diverging to the left on two legs 68 and 57 framing this frame separated therefrom by the lines 50 and 51 to the points 50a and 51a,
the parallelogram-shaped knot 59 is defined by two parallel biases 52 and 53 tilting from the left downwards to the right upwards to connect legs 58 and 57 to the chord 6.5 beyond the breakpoints 51 a and 50b cutting lines 51 and 50 which separate this frame 6.5 said jambs 58 and 57 extending on either side in prolongation.

To deploy the sheet 5 thus precut, it is necessary, as is clear from Figure 3:
immobilize longitudinally in a base plane the members of odd rank 6.1, 6.3, 6.5, 6.7, 6.9 6.2n + 1,
and pull longitudinally on the members of even rank 6.2n, spacing them both transversely from the preceding and perpendicular to their base plane, this traction being alternated to the right for the members 6.4, 6.8 ...., 6.4n and to the left for members 6.2, 6.6 ..., 6.4n + 2.

Of course, during this movement, the legs tilt symmetrically, the legs 58 and 67 knots 89 even rank 4n + 2 down right (Figure 3) and the legs 68 and 57 of the knots 79 even rank 4n down to the left (figure 3). This inclination is accompanied by a folding of the legs at the location of the connecting nodes:
for the legs 57 along the fold line 57a of the even-rank node 79.4n and along the fold line 57b of the odd-rank node 59.4n + 1 (FIGS. 3 and 4),
for the legs 58 along the fold line 58a of the odd-rank knot 59.4n + 1 and along the fold line 58b of the even rank knot 89.4n + 2 (FIGS. 3 and 4),
for the legs 67 along the fold line 67a of the odd-rank knot 69.4n + 3 and along the fold line 67b of the rank knot 89.4n +2,
for the legs 68 along the fold line 68a of the even-rank node 79.4n and along the fold line 68b of the odd-rank node 69.4n + 3, all these fold lines connecting an interruption point 50a or 51a, 50b or 51b of the cutting lines 50, 51 of a chord, at the homologous interruption point situated opposite 51a or 50a, 51b or 50b of the cutting lines of the neighboring member,
FIG. 5 shows three sections 41.1 to 41.3 which, during assembly, are aligned one at the end of the others, the holding of the armature sections 1 is ensured only by their own rigidity.

 To ensure the connection of these sections together and to prevent cracking appear thereafter, transverse bars 42 are laid at different regularly spaced levels. These bars have nothing special except that hooks 43 and 44 are formed by the ends of each. The forming of the hooks is carried out by force and is intended to join the end chord of a section with the adjacent end chord of the contiguous section: thus, a true cranking of all the sections is obtained and ensures at the same time the connection intense chords that are close to the songs in contact with said sections.

 The armature 1 previously described in detail is stably erected to form at least one vaulted section defining an upper or upper face E and a lower face or lower surface I as shown in Figure 7a.

 The vertical stability of the armature section or sections 1 is ensured on the one hand by orienting said ribs in the conveying direction and on the other hand, by means of stiffening elements 100, formed on the one hand, in the curvature of the section microcintres comprising small-diameter steel bars placed in compression by post-compression means and, on the other hand, in the perpendicular direction of small-diameter steel bars integrated in the thickness of the reinforcement.

 Thus, a first series of stiffening elements is arranged parallel to the generatrices of the profile of the section while the other series is arranged according to the guidelines of said profile.

 An envelope 101 is then fixed on the upper face or extrados E as shown in FIG. 7b. This envelope is intended for the confinement of concrete by limiting losses at the extrados during projection. The casing 101 is constituted, if necessary, by a continuous waterproof and / or insulating sheet which possibly comprises cells.

 Of course, in the case where the armature 1 is disposed in contact or at a very short distance from the wall, the containment envelope is no longer necessary because the shotcrete is stopped by the wall.

 Next, on said armature, on the opposite side to said casing 101, is projected a concrete 102 with rapid setting and hardening as represented in FIG. 7c. The projection is carried out starting from the lower parts of the section and up towards the upper parts to form progressively and without breaking the stability a self-supporting structure with a thin wall and of substantially uniform thickness in which at least partially is embedded frame. The projection mode will be described in more detail in the example below. The projection of the concrete 102 from the intrados to the extrados produces a satisfactory coating of both the chords and the jambs (FIG. 7d). No bonding of the concrete is necessary on the envelope 101 and the projection of the concrete 102 is carried out dry with prior wetting of the concrete.

 According to the embodiment shown in FIGS. 7a to 7d, the self-supporting structure is produced in situ for example inside the excavation T previously excavated. The retaining and / or lining structure is then built directly under the vault and progressing progressively in the excavation.

 According to another variant, the self-supporting structure is made remote from the site and then the finished structure is moved to the structure to be built or consolidated.

 The concrete 102 used in combination with the previous armature 1 contains a fast setting and hardening hydraulic binder.

Preferably, the concrete comprises from 300 to 800 kg of binder per cubic meter of concrete used by projection as well as aggregates whose size is between 0 and 15 mm.

 The water / hydraulic binder ratio is set between 0.25 and 0.50.

 The hydraulic binder used has both a fast setting time and improved mechanical properties and good resistance to chemical attack with lower thermal development costs.

 Fast curing and hardening cements means cements which start at 20 ° C between 2 and 60 minutes, and whose end time is 2 to 15 minutes after.

 This definition clearly distinguishes these quick setting and hardening cements of conventional cements as defined in the standard NF P15-301 which indicates in paragraph 7-2.2 that start times at 20C are greater than 1H 30 minutes for Class 35 and 45 cements, and greater than 1H for Class 55 and HP cements

 The rapid setting and hardening hydraulic binder used contains from 50 to 99% of a natural cement resulting from the calcination at a temperature of 900 to 1200 ° C of a single raw material containing sulphured clay phases and calcium carbonate. in an intimate mixture and from 1 to 50% of a pozzolanic product and / or a product acting as "filler".

 The calcination temperature of the raw material constituting the natural cement is such that it leads to a product not containing mainly the characteristic phase of clinkers that are found in artificial cements, including PORTLAND type cement.

 By product acting as "filler" is meant a finely divided product deemed to be chemically inert and improving the compactness of the cement matrix by a granular effect.

 Examples of products acting as filler include calcareous products as well as non-reactive varieties of silica fumes.

 By pozzolanic type product is meant products capable of forming with lime hydrated calcium silicates similar to those produced during the hydration of a conventional artificial cement clinker.

 By way of example of pozzolanic products that can be used to prepare the compositions according to the invention, mention may be made of natural pozzolans, for example volcanic pozzolans, artificial pozzolans, for example clays that are thermally activated and quite advantageously industrial waste. and especially the silica fumes. These silica fumes are industrial waste resulting from the manufacture of aluminum and are mainly composed of amorphous silica grains of less than one micron size. They have the advantage of playing both the role of filler and pozzolanic product.

 The hydraulic binders used also contain from 0 to 10% of an inorganic inorganic sulfate type addition.

 By way of example of sulphates which may be used according to the invention, mention may be made of calcium sulphate, anhydrous or dihydrate, and sodium and calcium double sulphate (glauberite).

 The addition of sulphated derivatives is particularly advantageous in binders because of the presence in the raw material constituting sulphurized elements which, at the time of hydration, combine with sulphated derivatives to form specific hydrates.

 According to other variants, the hydraulic binder compositions also contain up to 5% of organic additions intended to improve the hydration of said binder during its use.

 As examples of such organic additions, the products conventionally used to modify the rheology and / or the quantity of water required for the handling and / or the setting and / or hardening kinetics are particularly suitable.

By way of examples of such organic additives, mention may be made of:
lignosulphonates,
gluconates,
naphthalene,
melamine,
- progressing regularly over time over several years and excellent resistance to chemical attack.

 Thus, at ordinary temperature of 20 ° C., the organic binders mentioned above lead, for 1/1 mortars, to start-setting times of the order of 6 minutes and to the end of the setting of the order of 9 minutes.

 The start times of setting can be increased if necessary, according to a technique known to those skilled in the art, for example, by adding citric acid in the mixing water. Thus, the addition of 0.2, 0.4, 0.6 or 0.8% of citric acid will make it possible to increase the starting time at 20 ° C respectively by 10, 15, 25 or 30 minutes. .

 These hydraulic binders make it possible to obtain 1/1 mortars which, from the first quarter of an hour, have high strengths of the order of 7 MPa in compression and 1.8 MPa in flexion, and which progressively change over time.

Thus for 1/1 mortars by weight and a water / hydraulic binder dosage between 0.30 and 0.38, compressive strengths of:
- 8 to 40 MPa at the end of lh,
- 15 to 15 to 50MPaobout24h,
- 35 to 75 MPa after 28 days.

 In addition, these hydraulic binders lead to mortars and concretes of excellent resistance to chemical attack. By way of example, a test tube immersed for one year in lactic acid at pH = 4 loses less than 1% of its weight.

 The aforementioned hydraulic binders have the advantage of giving, with the artificial cements or their PORTLAND-type clinkers, fully compatible and stable mixtures over time and which are particularly well adapted to their incorporation into concretes to be sprayed.

 These mixtures may contain from 0.1 to 99.9% of hydraulic binder and have the advantage of providing a means of modulating at will the mechanical properties and the setting speed of the products thus obtained.

 Thus the particular binders obtained by mixing the aforementioned hydraulic binders with artificial cements have, at dosages greater than 30% (in mortar 1/2 for example), intermediate and progressive mechanical setting and strength properties between the properties of the binders. previously described and those of artificial cement, that is to say that some assays can have a rapid setting, mechanical resistance measurable from 3 pm and resistances to 28 days equal to those of artificial cement.

 The mechanical strengths continue to rise significantly up to 3 months and more.

 Particularly interesting mixtures are mixtures with cements with strong additions of pozzolanic materials very weak at young age. Their mixtures with the above-mentioned binders very clearly improve their mechanical strength at young age, from 3 hours and up to 6 days depending on the dosage considered.

 The structure of the invention reacts in its elastic domain, without degradation with very good transverse stiffness and good tensile strength. The stability and strength of this self-supporting structure allow a safe use especially in underground structures such as tunnels whose excavation is normally supported according to the geology of the ground.

 The following example illustrates an embodiment of the method of the invention.

 A three-dimensional galvanized steel monolithic frame 1 is used, manufactured and distributed by J.K.

STRUCTURES (Trademark) of the type previously described for forming sections 3 m long and 1.20 m wide which are bent to accommodate the radius of curvature of the excavation of a tunnel.

 During the assembly of the sections, the circulation under the vault remains possible.

 Stops arranged along the generatrices of the building section define the laying template.

 The assembly of the section is made in an arch from the foot vault alternately right and left.

 The connection of the hoops to one another is obtained by overlapping a half-wave with stapling of the chords.

 During assembly, support gantries are used until a full arch is closed. As soon as the looping of an arc has occurred, longitudinal and transverse stiffening elements are integrated in the thickness of the reinforcement in the form of small diameter steel bars of the Poutrafils (registered trademark) type. The number, the position and the diameter of the bars are determined according to the radius of curvature of the section and the loads to be resumed. The loading is carried out by means of a post-compression device.

 The concrete is then sprayed on the reinforcement section.

 The projection is carried out in a confined manner to limit the concrete losses and progressively drown the reinforcement.

 The projection phase consists of making, by a first series of passes at the lanice, concrete arches spaced about 2 m (see Figure 7c). The passes are made starting from the lower parts of the section and then up to the high parts to form gradually and without breaking stability a self-supporting structure due to the rapid rise in strength of the concrete. The weight of the concrete arches is balanced by the self-supporting capacity of the section reinforced by the stiffening elements.

 The second set of passes consists in projecting the concrete into the areas of the frame that remain empty after the first pass, always starting with the lower parts and without any support being necessary.

 The concrete used contains a hydraulic binder Vicalpes type (trademark) manufactured and distributed by the VICAT Company which is quick setting and hardening in contact with water.

 For the first passes, the concrete contains 470 kg of Vicalpes per cubic meter of concrete used.

 For subsequent passes, the concrete contains 180 kg of vicalpes per cubic meter of concrete. The concrete also contains aggregates whose size is less than or equal to 8mm the water / binder ratio is 0.35.

A tap start shifter is added and the projection is done by dry dilute flow. The concrete is hydrated to 3% maximum, first upstream and then at the end of the lance by a complementary hydration.

 The projection rate is limited to 2.5 m3 / hour. The coating of the reinforcement and the compactness of the concrete are very satisfactory.

 The thickness of the structure obtained is uniform and is chosen between 7 and 12 cm.

Claims (43)

 1. A method for producing a self-supporting structure for civil engineering works and in particular underground structures, characterized in that it consists in stably raising at least one three-dimensional monolithic metal reinforcement section (1) to projecting confinedly on said frame (1), a concrete (102) fast setting and hardening, starting from the lower parts of the section and going up to the high parts to form gradually and without breaking the stability, said structure self-supporting thin-walled and substantially uniform thickness in which is at least partially embedded said armature (1).  2. Method according to claim 1, characterized in that said armature section is defined so as to define an upper face or extrados (E) and a lower face or intrados (I).  3. Method according to claim 2, characterized in that fixed on the extrados (E) an envelope (101) for confining the concrete (102) projected between the intrados (I) and the extrados (E) .  4. Method according to one of claims 1 to 3, characterized in that said structure is made in situ.  5. Method according to one of the preceding claims, characterized in that the projection of the concrete (102) is carried out dry with prior wetting.  6. Method according to claim 3, characterized in that said envelope (101) consists of a waterproof sheet and / or insulating.  7. Method according to one of the preceding claims, characterized in that ensures the stability of the armature section including by means of stiffening elements (100) formed on the one hand, in the curvature of the section of microcintres comprising small diameter steel bars put in compression by means of post-compression and secondly in the perpendicular direction of small diameter steel bars integrated in the thickness of the frame (1).  8. Method according to one of the preceding claims, characterized in that said concrete (102) comprises a hydraulic binder containing from 50 to 99% of a natural cement resulting from calcination at a temperature between 900 and 1200-C: of a single raw material containing sulphured clay phases and calcium carbonate in an intimate mixture and from 1 to 50% of a pozzolanic product or acting as filler.  9. The method of claim 8, characterized in that said concrete comprises 300 to 800 kg of hydraulic binder per cubic meter of concrete used.  10. Method according to one of claims 8 or 9, characterized in that said concrete comprises aggregates whose size is between 0 and 15 mm.  11. Method according to one of claims 8 to 10, characterized in that the water / hydraulic binder ratio of the concrete is between 0.25 and 0.50.  12. Method according to one of the preceding claims, characterized in that said armature (1) has on its outer faces members parallel to each other and heart inclined legs connecting these frames; said chords being oriented in the carrier direction.  13. The method of claim 12, characterized in that each node (79,89) of each even-rank member (6.4n) defining a first face of the armature is shaped in a triangle and couples the adjacent ends of two legs ( 57 and 68, 67 and 58) respectively extending on both sides of the frame considered and in the same direction, the directions reversing for the legs of the two consecutive members of even rank (6.4n and 6.4n + 2), and in that each node (59, 69) of each odd-rank member (6.4n + 1) defining the second face of the structure is shaped as a parallelogram and couples the adjacent ends of two legs (57 and 58, 67 and 68). ) extending respectively on both sides of the frame considered and in opposite directions, the directions s inverting for homologous legs of two consecutive members of odd rank (6.4n + 1 and 6.4n + 3).  14. The method of claim 12 or 13, characterized in that the connecting nodes (59,69,79,89) are arranged on the undeployed flat metal along lines perpendicular to the ribs; and in that, during the deployment, if the parallelogram nodes (59, 69) of the odd-sized members (6.4n + 1) are longitudinally immobilized, the triangular nodes of each even-numbered chord are displaced longitudinally, sometimes in one direction (79), for a member of even rank (6.4n) considered, and sometimes in the opposite direction (89), for the two members of even rank (6.4n + 2) consecutive thereto, so that the legs tilt by opposing for two consecutive members of even rank while the first face defined by them departs from the second face defined by the odd-sized members.  15. The method of claim 13 or 14, characterized in that during deployment of the previously cut metal sheet, the ribs are spaced transversely from each other.  16. The method as claimed in claim 15, characterized in that each parallelogram coupling node (59, 69) of an odd-numbered frame (6.4n + 1) is constituted by the portion thereof on which the two ends terminate. jambs (57 and 58, 67 and 68) of opposite directions coupled thereto, as well as the ends of these legs which are separated from those of the legs extending in extension by two cutting angles (52 and 53, 54 and 55), which are parallel to one another and to the line connecting two diagonally opposite points of this portion, the cutting angles of an odd-sized chord being inclined symmetrically with respect to those of the two consecutive ones of odd rank.  17. The method as claimed in claim 15, characterized in that each triangular coupling node (79, 89) of an even-numbered chord (6.4n) consists of the part of the latter on which the two legs ( 57 and 68, 67 and 58) of the same direction coupled thereto, as well as the ends of these legs which are separated from those of the legs extending in extension by two cutting angles (52 and 55, 53 and 54). , which are parallel respectively to the two lines which diagonally connect the four points of this part, the cutting angles of a chord of even rank converging opposite to those of the two consecutive members of even rank.  18. Method according to one of claims 13 to 17, characterized in that, at the time of mounting armature sections extending from each other and in contact by their extreme edges defined by the even end members (6.2n) of the first face and odd (6.2n + 1) of the second face, the chords of each section cooperate with transverse bars (40) regularly spaced whose ends (41,42) are fixed, in particular by force-clamping, on the chords of two contiguous sections.  19. Self-supporting structure for civil engineering works and particularly underground structures, characterized in that it comprises at least one three-dimensional monolithic metal reinforcement section (1) coated with a concrete comprising a hydraulic binder and fast curing to obtain a thin wall and a substantially uniform thickness in which is at least partially embedded said armature.  20. Structure according to claim 19, characterized in that said binder consists of 50 to 99% of a natural cement resulting from the calcination at a temperature of 900 to 1200 ° C of a single raw material containing sulphurous clay phases and calcium carbonate in an intimate mixture and from 1 to 50% of a pozzolanic product or acting as filler.  21. Structure according to claim 19 or 20, characterized in that the pozzolanic or filler product is derived from the recovery of an industrial waste or the manufacture of an artificial pozzolan.  22. Structure according to one of claims 19 to 21, characterized in that the pozzolanic derivative or filler type is composed of silica fumes, consisting of amorphous silica grains less than I Fm (micron).  23. Structure according to one of claims 19 to 22, characterized in that the binder contains from 0 to 10% of an inorganic inorganic sulfate type addition.  24. Structure according to claim 23, characterized in that the sulphate-type addition is an anhydrous calcium sulphate or dihydrate or a double sulphate of sodium and calcium.  25. Structure according to one of claims 19 to 24, characterized in that the binder additionally contains less than 5% of an organic addition intended to improve the hydration of said binder during its use.  26. Structure according to claim 25, characterized in that said organic addition belongs to the group consisting of lignosulphonates, gluconates, naphthalene, melamine, polyhydroxycarboxylic products, polyvinylsulphonated products, anhydrous citric acid or monohydrate, plasticizers and superplasticizers.  organic addition 0.1 - 0.5%.  inorganic addition: 1 - 10%  pozzolanic and / or filler product: 3.9 - 11.5%  natural cement: 85 - 95%  27. Structure according to one of claims 19 to 26, characterized in that the binder contains in percentage by weight:  28. Structure according to one of claims 19 to 27, characterized in that the concrete comprises the mixture of said binder with an artificial cement or clinkers PORTLAND type.  29. Structure according to claim 28, characterized in that it contains from 0.1 to 99.9%, preferably from 10 to 90% of said binder.  30. Structure according to claim 28 or 29 characterized in that said artificial cement is a cement with a strong addition of pozzolanic materials, for example a slag cement or pozzolan.  31. Structure according to one of claims 19 to 30, characterized in that said concrete comprises aggregates whose size is between 0 and 15 mm.  32. Structure according to one of claims 19 to 31, characterized in that said concrete comprises aggregates whose size is between 0 and 15 mm.  33. Structure according to one of claims 19 to 32, characterized in that the water / hydraulic binder ratio of the concrete is between 0.25 and 0.50.  34. Structure according to one of claims 19 to 33, characterized in that said armature has on the surface members parallel to each other and heart inclined legs connecting these frames.  35. Structure according to claim 34, characterized in that each node (79,89) of each even-rank chord (6.4n) defining a first face of the structure is shaped as a triangle and couples the adjacent ends of two legs (57). and 68, 67 and 58) respectively extending on both sides of the frame considered and in the same direction, the directions reversing for the legs of the two consecutive members of even rank (6.4n and 6.4n + 2), and in that each node (59,69) of each odd-rank member (6.4n + 1) defining the second face of the structure is shaped in a parallelogram and couples the adjacent ends of two legs (57 and 58, 67 and 68). extending respectively from both sides of the frame considered and in opposite directions, the directions reversing for homologous legs of two consecutive members of odd rank (6.4n + 1 and 6.4n + 3).  36. Structure according to claim 34 or 35, characterized in that the connection nodes (59,69,79,89) are arranged on the undeployed flat metal along lines perpendicular to the ribs; and in that, during deployment, if the parallelogram nodes (59, 69) of the odd-sized members (6.4n + 1) are immobilized longitudinally, the triangular nodes of each even-numbered chord are displaced longitudinally, sometimes in one direction (79), for a member of even rank (6.4n) considered, and sometimes in the opposite direction (89), for the two members of even rank (6.4n + 2) consecutive thereto, so that the legs tilt by opposing for two consecutive members of even rank while the first face defined by them departs from the second face defined by the members of odd rank.  37. Structure according to claim 36, characterized in that, during the deployment of the previously cut metal sheet, the ribs are spaced transversely from each other.  38. The structure as claimed in claim 36, characterized in that each parallelogram coupling node (59, 69) of an odd-numbered chord (6.4n + 1) is constituted by the part of the latter on which the two ends. jambs (57 and 58, 67 and 68) of opposite directions coupled thereto, as well as the ends of these legs which are separated from those of the legs extending in extension by two cutting angles (52 and 53, 54 and 55), which are parallel to one another and to the line connecting two diagonally opposite points of this portion, the cutting angles of an odd-sized chord being inclined symmetrically with respect to those of the two consecutive ones of odd rank.  39. The structure as claimed in claim 36, characterized in that each triangular coupling node (79, 89) of an even-numbered chord (6.4n) consists of the part of the latter on which the two legs (57 and 68, 67 and 58) which are coupled thereto, as well as by the ends of these legs which are separated from those of the legs extending in extension by two cutting angles (52 and 55, 53 and 54), which are parallel respectively to the two lines which diagonally connect the four points of this part, the cutting bias of a chord of even rank converging opposite to those of the two consecutive members of even rank.  40. Structure according to one of claims 33 to 39, characterized in that the frames are oriented in the carrier direction.  41. Structure according to one of claims 19 to 40, characterized in that it is shaped to define an upper face or extrados (E) and a lower face or intrados (I).  42. Structure according to one of claims 19 to 41, characterized in that it comprises stiffening elements (100) formed on the one hand, in the curvature of the section of microcintres comprising small diameter steel bars put in compression by means of post-compression and, secondly, in the perpendicular direction of small diameter steel bars integrated in the thickness of the frame (1).  43. Use of the structure according to one of claims 19 to 42 to achieve an internal structure for retaining and / or coating the arch of a tunnel.