Boring assembly and associated boring method

A boring assembly extends along a main axis and comprises a boring head comprising at least one first nozzle and at least one second nozzle The or each second nozzle is different from the or each first nozzle. The boring assembly includes a first delivery device configured to deliver a jet of abrasive-free water at a pressure comprised between 2000 bar and 4000 bar to the at least one first nozzle. The boring assembly includes a second delivery device configured to deliver a jet containing at least one abrasive material at a pressure comprised between 2000 bar and 6000 bar to the at least one second nozzle.

The present invention relates to a boring assembly extending along a central axis. The invention also relates to a boring method.

In particular, the invention relates to boring in a civil engineering structure, in particular during the dismantlement of nuclear power plants.

BACKGROUND

The boring technique by hollow core drilling is known using a boring crown with the same diameter as the hole to be made in the structure.

However, this technique does not make it possible to produce inclined boreholes in a satisfactory manner. Indeed, at the end of boring, part of the boring crown still pierces the structure, while the rest of the crown protrudes outside the structure and can damage an equipment item located near the structure.

Also known from US20120067184 is a boring system for performing the hydrodemolition of concrete. The system comprises a boring head configured to supply a high-pressure jet of water and another boring head configured to supply an abrasive jet.

However, the handling of such a system is complicated.

SUMMARY

The aim of the present disclosure is then to propose a boring system making it possible to simplify handling thereof.

To that end, a boring assembly of the aforementioned type is provided, comprising:a boring head including:at least one first nozzle;at least one second nozzle, the or each second nozzle being different from the or each first nozzle;a first delivery device configured to deliver a jet of abrasive-free water at a pressure of between 2000 bar and 4000 bar to the at least one first nozzle;a second delivery device configured to deliver a jet containing at least one abrasive material at a pressure of between 2000 bar and 6000 bar to the at least one second nozzle.

The handling of the boring assembly according to the present disclosure is simpler. Indeed, the boring using the boring assembly according the present disclosure does not require the alternating introduction of several boring heads, as is the case for the boring systems of the state of the art, which causes lost time and boring imprecisions.

According to other advantageous aspects of the present disclosure, the boring assembly comprises one or more of the following features, considered alone or according to any technical possible combinations:the boring head is cylindrical, and has a central head axis extending along the main axis;the boring head has a diameter of between 200 mm and 1000 mm;the boring assembly comprises a frame and a first rotational drive of the boring head relative to the frame around the central head axis;the boring assembly comprises a body, a first cylindrical support having a first support central axis different from the central head axis and a second rotational drive of the first support relative to the body around the first support central axis, the at least one second nozzle being arranged on the first support, and the first support being connected to the body in rotation around the first support central axis;the boring assembly comprises a second cylindrical support having a second support central axis different from the first support central axis, a third rotational drive of the second support relative to the first support around the second support central axis, the at least one first nozzle being arranged on the second support, and the second support being connected to the first support in rotation around the second support central axis;the at least one second nozzle is configured to deliver an adjustable jet forming an angle between 0° and 45° relative to an axis passing through the second nozzle and parallel to the main axis;the boring assembly comprises a rubble suction port, preferably arranged in the body and extending along the main axis;the boring head comprises a lighting device and a camera, preferably supported by the first support;the boring assembly comprises a fourth drive of the boring head in translation along the main axis relative to the frame;the boring head has a front face substantially orthogonal to the main axis, the first nozzle and the second nozzle emerging on the front face.

The present disclosure also relates to a boring method using a boring assembly as described above, comprising the following steps:first delivery by the first delivery device of a jet of abrasive-free water at a pressure of between 2000 bar and 4000 bar to the at least one first nozzle;second delivery by the second delivery device of a jet containing at least one abrasive material at a pressure of between 2000 bar and 6000 bar to the at least one second nozzle; the first delivery having taken place before, during and/or after the second delivery.

According to another advantageous aspect of the present disclosure, the boring method comprises the following steps:demolition of the concrete body by the jet of abrasive-free water delivered during the first delivery,cutting of a metal element by the jet including at least one abrasive material delivered during the second delivery.

DETAILED DESCRIPTION

The boring assembly10is configured to bore a wall12, in particular a wall12including mineral and metallic elements. In particular, the wall12is made from reinforced concrete made up of concrete14and metallic elements16. The metallic elements16are for example bars of iron or steel.

The boring assembly10extends along a main axis A-A′.

The boring assembly10comprises a boring head18including at least one first nozzle20and at least one second nozzle22, the or each second nozzle22being different from the or each first nozzle20.

As shown inFIG. 1, the boring assembly10comprises, in the example illustrated in the figures, a single first nozzle20and a single second nozzle22.

As visible inFIG. 2, the boring head18is cylindrical. The boring head18has a central head axis B-B′ extending along the main axis A-A′.

Advantageously, the boring head18has a diameter greater than 200 mm. In theory, the diameter has no upper limit. For applications to civil engineering, the boring head18has a diameter in particular of between 200 mm and 1000 mm, for example 280 mm.

The drilling head18has a front face24, the front face24being configured to be arranged across from the zone of the wall12to be bored. The front face24is substantially orthogonal to the central head axis B-B′.

The or each first nozzle20is configured to deliver a jet of fluid, in particular a jet of abrasive-free water.

An abrasive refers to a very hard material used to wear down other, softer materials. In particular, the abrasive material has a hardness greater than 6 mohs. An abrasive material is also characterized by its particle size, which is advantageously between 30 and 80 mesh.

The or each second nozzle22is configured to deliver a jet of fluid, in particular a jet including at least one abrasive material. The abrasive material is for example made up of garnet or almandine. Advantageously, the fluid is water in which the abrasive material is added.

The boring assembly10further comprises a first delivery device26and a second delivery device28.

The first delivery device26is configured to deliver the jet of abrasive-free water to the at least one first nozzle20.

In particular, the first delivery device26is configured to deliver the jet of water at a very high pressure in order to allow the boring by demolition by spalling of the concrete14. The very high pressure of the jet of water is between 2000 bar and 3000 bar. The flow rate associated with the jet of water is between 10 l·min−1and 20 l·min−1.

The boring assembly10advantageously comprises at least one third nozzle, not shown in the figures.

The first delivery device26is further configured to deliver a jet of abrasive-free water at low pressure to the at least one third nozzle in order to allow the discharge of the rubble from the zone of the wall12to be bored. In particular, the low pressure of the jet of water is between 2 bar and 10 bar. The flow rate associated with the jet of water is then between 20 l·min−1and 100 l·min−1.

The first delivery device26advantageously includes a tank comprising water, a pump and a pipe from the tank to the or each first nozzle20, not shown.

The second delivery device28is configured to deliver the jet including at least one abrasive material to the at least one second nozzle22. The pressure of the abrasive jet is between 2000 and 3000 bars. The flow rate associated with the abrasive jet is then between 200 and 500 g·min−1.

The second delivery device28advantageously includes a tank comprising an abrasive material, a pump and a pipe from the tank to the or each second nozzle22, not shown.

Advantageously, the boring assembly10further comprises a frame30and a first drive32.

The frame30is a support located separately from the wall12. The frame30is stationary relative to the wall12.

The first drive32is configured to rotate the boring head18relative to the frame30around the central head axis B-B′. Advantageously, the amplitude of the rotation allowed by the first drive26is 360°.

The first drive32is of any appropriate type to allow said rotation. For example, the first drive32is a gear motor.

The boring assembly10also comprises a body34, a first support36and a second drive38.

The body34has a cylindrical shape, having the head axis B-B′ as central axis and the same diameter as the boring head18. The front face of the body34is parallel to and substantially at the same level as the front face24of the boring head18.

The first support36is cylindrical, having a first support central axis C-C′ different from the central head axis B-B′. The first support central axis C-C′ is for example substantially parallel to the central head axis B-B′. In a variant, the first support central axis C-C′ forms a non-nil angle, in particular between 0° and 45° with the central head axis B-B′.

As shown inFIGS. 4 and 5, the or each second nozzle22is configured to deliver an adjustable jet forming an angle between 0° and 80° relative to an axis F-F′ passing through said second nozzle22and parallel to the first support axis C-C′.

As shown inFIG. 2, the first support36is inserted into the body34. Advantageously, the first support36is connected in rotation to the body34around the first support central axis C-C′. The first support36emerges on the front face24. The first support front face36is for example parallel to and substantially at the same level as the front face24of the boring head18.

The or each second nozzle22is arranged on the first support36and, in particular, on the front face of the first support36.

The second drive38is configured to rotate the first support36relative to the body34around the first support central axis C-C′. Advantageously, the amplitude of the rotation allowed by the second drive28is 180°.

The second drive38is of any appropriate type to allow said rotation. For example, the second drive38is a gear motor.

By combination between the rotation allowed by the first drive32and the rotation allowed by the second drive38, the nozzles20,22are able to follow any desired path on the front face24.

In one advantageous embodiment, the boring assembly10further comprises a second support40and a third drive42.

The second support40is cylindrical, having a second support central axis D-D′ different from the first support central axis C-C′. The second support central axis D-D′ is advantageously substantially parallel to the first support central axis C-C′. In a variant, the second support central axis D-D′ forms a non-nil angle with the first support axis C-C′.

As shown inFIG. 3, the or each first nozzle20is configured to deliver a jet forming an angle of between 0° and 45° relative to an axis E-E′ passing through said first nozzle20and parallel to the second support central axis D-D′. As shown inFIG. 2, the second support40is inserted into the first support36. Advantageously, the second support40is connected in rotation to the first support36around the second support central axis D-D′. The second support40emerges on the front face24. The front face of the second support40is parallel to and substantially at the same level as the front face24of the boring head18.

The or each first nozzle20is advantageously arranged on the second support40. In particular, the or each first nozzle20is located on the front face of the second support40.

The third drive42is configured to rotate the second support40relative to the first support36around the second support central axis D-D′. Advantageously, the amplitude of the rotation allowed by the third drive42is 360°. In particular, the third drive42is configured to allow a continuous rotation of the second support40, in particular at a rotation speed of between 100 and 600 rpm.−1, for example 500 rpm−1.

The third drive42is of any appropriate type to allow said rotation. For example, the third drive42is a gear motor.

In a variant, the third drive42is configured to allow the rotation of the second support40using the water flow circulating through the or each first nozzle20.

Advantageously, the boring assembly10comprises a suction port44.

The suction port44is arranged in the body34and the opening of the suction port44emerges on the front face24. The suction port44extends along the central head axis B-B′.

The suction port44is configured to suction, through the opening, rubble originating from the boring of the wall12as well as the fluids injected by the nozzles20,22and to transport the rubble and the fluids from the front face24toward the outside of the wall12.

The suction port44is advantageously connected to a pump, not shown, configured to create a vacuum causing the suction and the transport of the rubble and fluids.

The boring assembly10advantageously comprises a lighting device46and a camera48.

The lighting device46is supported by the first support36, in particular on the front face of the first support36. The lighting device46is configured to illuminate the zone of the wall12to be bored. The lighting device46is advantageously made up of a plurality of bulbs arranged evenly in a circle around the camera48.

The camera48is supported by the first support36, in particular on the front face of the first support36. The camera48is configured to record and transmit to a screen, not shown and located outside the wall12, photographs or videos of the zone of the wall12to be bored. Advantageously, the camera48is configured to instantaneously transmit the acquired images to the screen in order to allow between control of the boring.

Advantageously, the lighting device46and the camera48are configured to go from a hidden configuration in which the lighting device46and the camera48are protected during the boring, to an active configuration in which the lighting device46and the camera48are able to illuminate and film the zone of the wall12to be bored.

Advantageously, the boring assembly10comprises at least one fourth nozzle, not shown in the figures, configured to supply a jet of compressed air on the lighting device46and the camera48in order to clean them and/or protect them from drippings during viewing steps after the boring steps.

The boring assembly10also comprises a fourth drive50.

The fourth drive50is configured to translate the boring head18along the central head axis B-B′ relative to the frame30and thus to make it possible to advance the boring of the wall12as the reinforced concrete is bored.

The fourth drive50is of any appropriate type to allow said translation. For example, the fourth drive50is a screw-nut system or a rack.

A boring method using the boring assembly10will now be described.

Initially, the boring assembly10is separated from the wall12.

The front face24of the boring head18is placed facing the wall12using the fourth drive50, which moves the boring head18in translation along the central head axis B-B′ relative to the frame30.

The first drive32and the second drive38place the boring head18and the first support36in the desired position facing the zone of the wall12to be bored.

If the zone of the wall12to be bored is made from concrete14, the boring method then comprises a step for first delivery by the first delivery device26of a jet of abrasive-free water at very high pressure to the or each first nozzle20. The concrete body14is then demolished by the very high-pressure jet of abrasive-free water, as shown inFIG. 3. Advantageously, a thickness of concrete14of between 40 mm and 60 mm is demolished during the first delivery step.

In particular, the third drive42rotates the or each first nozzle20around the second support central axis D-D′ relative to the first support36. The described jet of abrasive-free water then describes a cone around the second support central axis D-D′, as shown inFIG. 3, thus allowing an easier demolition of a thickness of concrete14.

By combination between the rotation done by the first drive32and the rotation done by the second drive38, the or each first nozzle20describes the desired path and makes it possible to remove a layer of the wall12made from concrete14along the diameter of the boring.

Additionally, the fourth drive50translates the boring head18by levels as the zone made from concrete14of the wall12is demolished.

Between each demolition level of the concrete14, the lighting device46and the camera48go from the hidden configuration to the active configuration. The lighting device46illuminates the zone to be bored and the camera48films and transmits the images of the zone of the wall12to be bored in order to control the boring and identify the metallic elements16that may be removed, in particular the steel or iron bars.

When the front face24is across from a metallic element16, the step for first delivery of the very high-pressure jet of abrasive-free water stops.

When the concrete zone14to be bored has been demolished, the first delivery device26delivers a low-pressure jet of abrasive-free water to the or each third nozzle in order to remove the rubble present across from the front face24. The suction port44suctions the water injected by the jet and the rubble and transports them outside the wall12.

The lighting device46and the camera48make it possible to identify the position and the shape of the metallic element16.

The first drive32and the second drive38place the boring head18and the first support36in the desired position facing the metallic element16to be destroyed.

The boring method then comprises a step for second delivery by the second delivery device28of a jet including at least one abrasive material to the or each second nozzle22.

The metallic element16is then cut by the abrasive jet, as shown inFIGS. 4 and 5.

The or each second nozzle22orients the abrasive jet as a function of the shape and the orientation of the metallic element16.

In particular, the or each second nozzle22makes it possible to cut a metallic element16oriented in substantially the same direction as the front face24, as shown inFIG. 4.

The or each second nozzle22also makes it possible to cut a metallic element16oriented substantially along the central head axis B-B′, as shown inFIG. 5, with a different orientation of the abrasive jet.

By combination between the rotation done by the first drive32and the rotation done by the second drive38, the or each second nozzle22describes the desired path and makes it possible to destroy the metallic element16precisely.

When the metallic element16has been demolished, the first delivery device26delivers a low-pressure jet of abrasive-free water to the or each third nozzle in order to remove the rubble present across from the front face24. The suction port44suctions the water injected by the jet and the pieces of iron and transports them outside the wall12.

In a variant, the suctioning is done during the demolition steps of the wall12, in order to remove the concrete rubble14and the cut metallic elements16continuously.

The terms “first delivery” and “second delivery” are used as simple terminology, but do not imply any relationship of temporal correlation between the steps of the boring method. The first delivery can thus be done before, during or after the second delivery.

Similarly to what has been described above, the boring method subsequently alternatively comprises first delivery steps to demolish the concrete zones14of the wall12and second delivery steps to destroy the metallic elements16present in the wall12.

The boring method therefore allows boring in a reinforced concrete wall12not requiring the alternating introduction of several boring heads and thus allowing easier handling of the boring assembly10. In addition to the time savings allowed by keeping the machine in place, the absence of round-trip is favorable to the reduced dispersion of rubble and effluents, which is a major point when working in a contaminated environment.

Additionally, the different drives32,38,42,50and the orientation of the jets at the outlet of the nozzles20,22make it possible to split the different elements14of the wall12into small enough residual rubble to be removed and transported by the suction port44using the stream of water injected by the or each third nozzle. In particular, the hydrodemolition allowed by the or each first nozzle20and the first delivery device26makes it possible to split the concrete14into pieces, the size of which is given by the mineral elements, such as stones, included in the composition of the concrete14. The precise cutting of the metal elements16using the controlled path of the or each second nozzle22makes it possible to split the metallic elements16, such as steel or iron bars, into small segments that are easily transportable by the suction port44.

The boring assembly10also makes it possible to perform an inclined boring without damaging the equipment items located near the wall12.

Inclined boring refers to boring done in a direction forming a non-nil angle with the axis normal to the outlet face, in particular an angle greater than 20° as shown inFIG. 1. The inclined boring is in particular advantageously done in a direction going from top to bottom.

Indeed, the metallic elements16are usually found in a civil engineering structure at least 50 mm inside the wall12. The alternating use of the nozzles20,22and abrasive cutting being able to be done in a targeted manner on the metallic sections, the end of the borehole may emerge outside the wall12without using the abrasive cutting jet. The use of the abrasive-free jet alone makes it possible not to cut any metallic elements beyond the borehole, and in particular to bore any metallic wall to be preserved.

Additionally, the alternating use of the two delivery devices22,24makes it possible to optimize the quantity of abrasives used, which makes it possible to reduce costs, as well as the ecological impact of the boring.

Lastly, the boring assembly10makes it possible to reduce the reaction forces of the jets, typically less than 10 daN, which lightens the structure and the necessary weight of the boring assembly10, unlike boring done with a pneumatic drill, for example, which leads to cracks in the structure.

The boring assembly10is in particular advantageously used to dismantle nuclear power plants having experienced accidents such as the Fukushima plant, for example.

The boring assembly10is also used to form openings in civil engineering structures when it is important to preserve the reinforcement bordering the opening so as to be able to subsequently remesh the structure when there is a new need.