The present invention relates to the reinforcing of civil engineering works, in particular civil engineering buildings or works such as the arched roofs of tunnels, bridges, pipes, etc, the term “civil engineering” here encompassing all types of constructions, whatever their purpose.

It may be necessary to reinforce these works during their lifetime, for example in order to compensate for their ageing structure.

It is customary to deploy structural reinforcements using techniques which are defined below.

One of the common methods consists in sheathing all or part of an element of the structure by installing one or more metal reinforcements. This technique requires, on the one hand, any gaps between the contact surfaces of the structure to be strengthened and the reinforcement employed to be filled and, on the other hand, the production of rigid inclusions connecting the existing structure to the reinforcement. The difficulty with this technique resides in particular in:

the significant resources required for it to be deployed on site, which make use of personnel and handling and injection equipment;

the limited ability to produce reinforcements with variable and accurate dimensions;

the quality of the continuity of the contact between the reinforcement and the structure to be strengthened.

A second currently used method consists in sheathing all or part of an element of the structure by installing a concrete reinforcement in the form of a shell or girder. This technique can require reinforcing cages, which may or may not be anchored in the existing structure, to be installed manually and formwork to be used before the concrete is put in place. The concrete is put in place in the traditional fashion using a concrete pump, by spraying, or by an element prefabricated before installation. The difficulty with this technique resides in particular in:

the resources required for it to be deployed on site which make use of personnel, handling equipment, and formwork;

the great difficulty in producing reinforcements with variable dimensions along the structure.

A third method consists in applying reinforcements based on composite materials in the form of mats, strips, or rods to the existing structure by manually gluing them. By way of example, the composite materials currently used are materials consisting of carbon fibers impregnated with an epoxy matrix. Such a method makes it possible to increase the tensile and shear strength of the elements of the existing structure but provides only little advantage in terms of an increase in their inertia.

These three techniques are sometimes combined.

Moreover, it is known in the building field to produce concrete structures using a technique similar to 3D printing with the aid of an extrusion head pilot-controlled from numerical data. The head is moved in successive planes of increasing height by a robot arm in order to extrude successive layers of the construction material according to the geometry to be produced. One layer is not deposited on the preceding one depending on the real-time acquisition of data relating to the relief of that portion of the work that has already been produced but depending on a 3D virtual mesh of the structure to be produced which is stored in a memory.

Patent application JP 2016 37808 discloses a system comprising a repair robot provided for repairing a tunnel, for example. This robot comprises means for digging out a crack and injecting an epoxy resin or a mortar into it with the aid of an injection nozzle. Such a robot has relatively limited possibilities in terms of repairing a work because in some cases the repair operations require much more than simply filling cracks.

Patent application JP 2005-299236 describes a robot system which also has the purpose of performing repairs. The repair material is delivered by a nozzle at a distance from the wall of the work to be repaired and applied against the wall by a pressing member associated with the nozzle. Such a system is not provided for applying successive layers of the repair material and does not allow the thickness of the material deposited to be varied to a great extent. Now some zones may require a greater degree of strengthening than others.

The object of the present invention is to overcome all or some of the abovementioned disadvantages of the usual repair methods and does so by virtue of a repair method for a civil engineering work, comprising the depositing, directly onto a portion of the work to be repaired, of a reinforcing structure formed from one or more successive layers of at least one reinforcing material, in particular in the form of strips which are each extruded in contact with the surface onto which the material is to be deposited, using a robot system.

“Contact extrusion” should be understood to mean that the outlet orifice of the nozzle through which the material exist is situated close to the surface on which the material is deposited, at a distance which is preferably in the order of the thickness of the deposited layer.

The invention makes it possible to easily reinforce civil engineering structures by applying thereon by extrusion multiple layers of a reinforcing material using a robot system, the latter preferably being pilot-controlled in real time by means which enable precise positioning relative to the work.

The reinforcing material can be extruded in a strip with a relatively constant dimension, in successive adhesive layers, so as to form the desired geometry. The level of the finishing can be adapted as needed.

The reinforcement formed by the extrusion of material can thus have a constant, flat, or projecting profile so as to optimize the quantity of reinforcing material used and be adapted to structural requirements and to the clearance conditions imposed by its use. The reinforcing structure can in particular be a variable-inertia ribbed shell or a variable-inertia ribbed girder.

Extrusion Head

The material is deposited with the aid of at least one extrusion head of the robot system.

It is advantageous if the extrusion head has a nozzle having a slot-shaped outlet orifice for the material. In this case, the nozzle can be moved in a direction perpendicular to the longitudinal axis of the slot. Other forms of outlet orifices are nevertheless possible.

The extrusion head can have a single nozzle or multiple nozzles.

The extrusion head is preferably arranged so as to deposit the material in the form of a strip.

The extrusion head is supplied by the material at a pressure sufficient to eject it via the outlet orifice of the nozzle.

Where appropriate, the extrusion head comprises a feed of reinforcing fibers which can be mixed in the extrusion head with base formulation of the material, in particular a cement-based formulation. The extruded material can also be prepared by introducing fibers upstream from the extrusion head.

The extrusion head can be equipped with all feed ducts for fluids for cleaning and/or rinsing the nozzle.

Acquisition of Relief Data

The method according to the invention preferably comprises the acquisition of relief data of the zone onto which the material is to be deposited and the automatic pilot-controlling of the extrusion head at least based on these relief data.

“Relief data” should be understood to mean data which provide information on the location of the surface on which the material is to be deposited relative to a known reference system of the robot system, such that the nozzle may be brought automatically into the appropriate position for depositing the material during extrusion.

The data can be 3D relief data, i.e. a spatial mesh is produced of the surface in question in the three dimensions of an orthonormal coordinate system. They may also be a succession of 2D scans in the planes of section spaced apart along the work, or even 1D scans along a girder, for example, so as to control the spacing between the nozzle and the surface onto which the material is to be deposited.

The relief data may be acquired with the aid of an acquisition system corresponding to the robot system, carried for example by the same robot arm as the extrusion head.

The acquisition of the relief data may comprise the acquisition of relief data in real time, simultaneously with the extrusion. These data may be used to position the extrusion head so as to orient it appropriately in order to deposit different successive layers of the material and to allow it to move relative to the work.

The acquisition of the relief data may in particular make it possible to maintain the nozzle at a predefined distance from the surface on which the material is to be deposited; this can be the surface of the work during the depositing of the first layer, or the surface of a previously deposited layer of material.

The acquisition of the relief data may also comprise the acquisition of relief data prior to extrusion.

It is possible, in an exemplary embodiment of the invention, to provide on the robot system an acquisition system which is used a first time in order to perform a scan of the portion of the work to be repaired, without depositing the material. This first acquisition may in particular be useful for calculating an optimum trajectory to be followed by the extrusion head, taking into account the form to be given to the reinforcing structure; once the trajectory has been calculated, the acquisition system can continue to be used in order to establish the position of the nozzle relative to the work and/or to reposition itself relative to the latter. This makes it possible to finely control the depositing of the different layers, in particular by maintaining the nozzle at the required distance from the depositing surface and with the desired orientation.

This acquisition may also take place using a corresponding acquisition system separate from the robot system.

The relief data may be acquired with the aid of at least one optical sensor by scanning with ultrasound or millimetric waves, and or with the aid of at least one mechanical probe. One or more cameras may be used, optionally with fringe projection, or a remote-controlled laser or ultrasound device, or a millimetric-wave radar, for example a Lidar-type radar.

When appropriate, the work is also surveyed at depth, for example simultaneously to the acquisition of the relief, for example in order to identify flaws in said work. When a radar is used to scan the surface, this radar can also be used to scan the thickness of the work. Where appropriate, these additional data are used to adapt the form of the reinforcing structure so as to, for example, thicken it in the zones where flaws have been detected. Real-time detection of flaws may be useful, for example, when inspecting a very long pipe and when preventively reinforcing zones where a potential weakness has been detected.

Reinforcing Structure

The number of layers deposited depends on the thickness to be given locally to the reinforcing structure and may lie, for example, between 1 and 100, preferably between 2 and 100. In particular, when the thickness to be given to the reinforcing structure is minimal, the number of layers may be 1, the number of layers being greater when the thickness of the reinforcing structure is not minimal. The reinforcing structure may comprise at least one portion where the number of superposed extruded layers is greater than 1.

The thickness of each layer depends on the rheology of the material and on its setting speed. It lies, for example, between 1 and 30 mm.

When the material is deposited in strips, the width of each strip lies between 3 and 50 mm.

The extrusion head is preferably guided so as to respect a preprogrammed algorithm for the reinforcing material so as to give the reinforcing structure its desired form. This algorithm may, where appropriate, take into account the creep of the material.

The aim of this algorithm may be, for example, to produce a reinforcing structure with a constant thickness along the portion of the work to be reinforced.

However, the method according to the invention makes it possible to easily produce a reinforcing structure with an optimum form which makes it possible to afford the required reinforcement, taking into account the stresses to which the work is exposed, whilst minimizing the quantity of material used.

The repair method may comprise smoothing the structure before it sets with the aid of a tool of the robot system, in particular a spreading blade. It is preferably a tool carried by the same arm of the robot system as the extrusion head.

This smoothing can take place only after the outermost layer has been deposited; as an alternative, one or more smoothing actions take place between the depositing of successive layers. Where appropriate, uneven depositing of the material may be detected automatically and a smoothing action is then initiated. This uneven depositing may be detected, for example, after acquiring a relief of the zone onto which the material is deposited.

The number of layers deposited and/or the thickness of the layers deposited may vary so as to produce a reinforcing structure with an inertia that varies. It is thus possible to minimize the quantity of material deposited whilst supplying the required reinforcement.

The reinforcing structure may be ribbed, the ribs being oriented longitudinally or transversely or in an intermediate direction, as required.

The reinforcing structure may be a girder which lies against for example, a face of a girder of the work to be reinforced, along at least part of the latter.

The reinforcing structure may also be a shell, in particular when reinforcing a dome-shaped or arched roof, for example of a tunnel.

The reinforcing structure may also be an anchor knob for distributing concentrated force, such as an anchor block for cables and/or tendons, in particular an anchor knob for additional prestressing cables, for deviating external prestressing cables, support cables, or cables for anchoring damping devices. Such knobs are used in particular on civil engineering works such as bridges.

The reinforcing structure may be produced with one or more blockouts by adapting the location of the deposited layers. Such blockouts are used, for example, for installing inserts, prestressing bars for strapping to the existing structure, plugs, or guides, and in particular cables.

Moving the Extrusion Head

The robot system can move independently, comprising for example a self-propelled platform.

As an alternative, the robot system comprises a platform which is pulled.

The robot system can move on wheels, tracks, cables, or skids.

It may be advantageous, when possible, for example when reinforcing a girder, to ensure that the work contributes to guide the robot system mechanically as it moves along the work when producing the reinforcing structure.

The guiding may take place, for example, by pressing the robot system against at least one surface of the work, in particular at least one surface defined by a girder of the work, for example multiple surfaces of the work including two opposite surfaces. The robot system thus moves along the girder, guided by the latter, and deposits the reinforcing material as it advances on the girder.

The accuracy of the depositing of the reinforcing structure is preferably greater than +/−0.5 cm in terms of thickness and/or in a direction parallel to the underlying surface of the work.

Reinforcing Material

The material used has a rheology which is compatible with its extrusion and the depositing of superposed layers, in particular in the form of strips.

The setting time for the material is preferably sufficiently long that a layer is deposited on a previously deposited layer before said previously deposited layer has set completely; maximum adhesion between the layers is thus guaranteed.

The extruded reinforcing material may be of different types.

It may, in particular, consist, depending on the structure in question and the reinforcement needs, of cement-based materials such as high-performance or ultra-high-performance concrete which may or may not be fiber-reinforced.

In the case of a structure to be reinforced which consists of a wooden framework, the reinforcing material used may consist of a mixture of resin and wood. The extruded material may thus comprise a resin.

Work to be Reinforced

The work to be reinforced pre-exists when the method according to the invention is implemented. The aim of the latter is to repair the work, i.e. to strengthen it by applying the reinforcing structure according to the invention.

The work to be reinforced may have been completed more than three months, six months, or a year before the method according to the invention is implemented.

The work may be an arched roof, in particular of a tunnel or a domed roof.

The work may also be a bridge, the portion of the work which needs to be repaired forming, for example, part of the deck of the bridge.

The invention also applies to the repairing of a hollow work such as a pipe, which may or may not be buried, or a mast, or a gallery which cannot be visited, the robot system preferably traveling along this pipe, this mastor this gallery, inside therein.

The work may also be made from masonry and the reinforcing structure which is deposited is used for repointing.

The majority of the work to be repaired may be made from concrete. The portion of the work to be repaired may also be made from metal or wood.

The subject of the invention is also a reinforcing structure which covers at least partially a civil engineering work, in particular a reinforcing structure in the form of a girder, shell, or knob, produced by implementing the method according to the invention.

The subject of the invention is also a civil engineering work which is repaired by installing on the work a reinforcing structure produced by implementing the method according to the invention.

The subject of the invention is also a robot system suitable for repairing a civil engineering work, comprising:

at least one extrusion head configured so as to form a reinforcing structure consisting of a reinforcing material directly on a portion of the work to be repaired, this reinforcing material preferably being a concrete, in particular a fiber-reinforced one, or comprising a resin,

a system for acquiring relief data on the zone onto which the material is to be deposited,

a calculator for automatically controlling the movements of the extrusion head relative to the work to be repaired, based on at least the relief data and the data about the form to be given on the work to the reinforcing structure, the movements of the extrusion head being controlled so as to extrude the material in successive layers, the extrusion of the material taking place in contact with the surface onto which the material is to be deposited.

This robot system may have all or some of the features described above in connection with the repair method according to the invention.

This robot system thus advantageously comprises:

an articulated arm carrying the extrusion head, in particular an arm with several degrees of freedom,

a platform which can move along the work, in particular a self-propelled or pulled platform, mounted on wheels, tracks, cables, or skids, the movement of which is controlled by the calculator,

a tool for smoothing the deposited structure before it sets, in particular in the form of a spreading blade, this tool preferably being carried by the same robot arm as the extrusion head,

means for automatically orienting a nozzle of the extrusion head perpendicularly to the surface onto which the reinforcing material is deposited, the extrusion head preferably comprising a slot-shaped nozzle.

