EP3673116A1

EP3673116A1 - Method and facility for concreting an underground site

Info

Publication number: EP3673116A1
Application number: EP18742775.2A
Authority: EP
Inventors: François PINEAU
Original assignee: Agence Nationale pour la Gestion des Dechets Radioactifs ANDRA
Current assignee: Agence Nationale pour la Gestion des Dechets Radioactifs ANDRA
Priority date: 2017-08-22
Filing date: 2018-07-17
Publication date: 2020-07-01
Anticipated expiration: 2038-07-17
Also published as: FR3070416B1; CN110998031B; EP3673116B1; CN110998031A; WO2019037958A1; FR3070416A1

Abstract

The invention relates to: - a method for concreting an underground site comprising the vertical routing of concrete (B) from a feeding site located at a higher altitude than the underground site towards the underground site by continuous feeding of concrete from a tube (A) for routing between the feeding site and the underground site, lowering a concrete column into the routing tube and collecting the concrete from a lower end of said concrete column to distribute the concrete in the underground site, characterised in that the routing tube is initially filled with a column of liquid (L) and a mobile shutter (1) positioned at the top of the liquid column, followed by exerting, during the lowering of the concrete column into the routing tube, a vertical counter-push on said shutter by adjusting the height of the column of liquid and/or the pressure of the liquid in the routing tube with a view to controlling the lowering of the concrete column; and - a facility for concreting an underground site located at great depth.

Description

METHOD AND INSTALLATION FOR CONCRETEING A UNDERGROUND SITE

The invention relates to a method and an installation for the concreting of a site located in an underground site at great depth. More particularly, although not exclusively, the invention relates to a method and an installation for the concreting, at great depth, radioactive waste storage cells, connecting galleries and access galleries to these storage caverns, access to these galleries being done by drilling.

PRESENTATION OF THE INVENTION [0003] In the field of civil engineering, concrete casting operations are carried out by means of traditional processes and installations including, in particular, pumping stations and flexible pipes ensuring the delivery of concrete. from the power plant to the construction site of the structure.

In the most common cases, the transport of concrete, from the concrete plant to the concrete site, requires the use of trucks. This mode of transport, although conceivable in the case of concreting an underground radioactive waste storage site, would, however, require a very long access ramp to reach the site at great depth, which would lead to a significant extension of time. transport, would increase the risk in terms of fire and increase the number of interruptions. According to the invention, it is therefore planned to carry out a direct delivery of the concrete using a vertical drilling.

Such processes and facilities are already used both for the construction of vertical structures of large dimensions (buildings, factories, towers, ....) for the renovation or the realization of tunnels and long-length bridges. Nevertheless, the known processes and installations are intended to convey concrete horizontally or upwards, but rarely downward.

In case of malfunction of these facilities, human intervention is generally possible because these facilities are easily accessible by the maintenance staff who have enough space around them to work.

[0007] Moreover, although the concreting operations consume a lot of water, in particular, for the cleaning of the site, wastewater management is generally possible in compliance with environmental regulations.

It is also noted that these civil engineering projects are generally short-term (from a few months to one or two years) and, as a result, companies do not wish to engage in heavy investments in the facilities which therefore remain always rudimentary and provisional. In the oil field, deep injection is reserved solely for the use of mortars or grout, which, given their composition, remain fairly homogeneous. In the case of concretes, the risk of blockage by accumulation of aggregates in the conveying tubes is greater. Concrete may also segregate resulting in separation of the granular phase of the cement phase.

In the particular case of a site located in a deep drilling (more than 500 meters in vertical and horizontal), as is the case for medium and high activity nuclear waste storage wells, the conveying concrete from the surface raises specific problems. First, assuming the concrete is conveyed by wells, any human intervention on the pipe is impossible which makes it difficult to manage and maintain the facility, including, in case of segregation concrete or clogging pipes.

In addition, because the concrete campaigns extend over very long periods (at least ten years), concrete flows are important (about 60 m3 / h in peak periods) and that the concrete has a specific and complex formulation that must retain its properties for several hours during its implementation, the difficulties mentioned above for the control of the descent of the concrete in the well are increased because a malfunction of the installation can then have adverse consequences on the progressive progress of the site, as well as on the operation, reliability and safety of the storage site.

In such circumstances, it may be necessary and urgent to stop the descent of the concrete and, if necessary, to bring it up to the surface before proceeding to clean the well.

The traditional methods and installations are clearly unsuited to meet these stringent requirements and to fulfill such conditions of implementation.

The invention aims to remedy these technical problems by providing means to ensure, reliably and securely and over a very long period, the descent and transport of concrete from the surface to the gallery and waste disposal cells located at great depths.

This object is achieved by means of a concreting process of an underground site comprising the vertical conveyance of a concrete from a feeding site located at an altitude higher than the underground site to the underground site by a power supply. continuous concrete flow of a transport tube between the feed site and the underground site, the descent of a concrete column in the conveying tube and the removal of concrete from a lower end of said column of concrete for distributing the concrete in the underground site, characterized in that initially filled the delivery tube with a column of liquid and a movable shutter positioned at the top of the column of liquid, it is then exercised during the descent of the concrete column in the conveying tube, a vertical counter-pressure on said shutter by adjusting the height of the liquid column and / or the pressure of the liquid in the conveying tube in order to to control the descent of the concrete column.

According to an advantageous characteristic of this method, the height of the liquid column and / or the pressure of the liquid is adjusted by pulling or withdrawing the liquid at a lower end of the conveying tube. It is possible in particular to implement a gravity withdrawal, by controlling the opening of a valve located at the lower end of the delivery tube, and taking advantage of the gravitational force applied by the concrete column on the shutter, pushing the latter. A bidirectional pump can also be used to extract the liquid at a controlled rate. According to another characteristic, it stops the drawing or withdrawal of the liquid when the movable shutter reaches the base of the conveying tube.

According to yet another characteristic, the continuous supply of concrete is made by injection of pressurized concrete from the surface at the latest as soon as the concrete column reaches the base of the tube. According to other features, the method of the invention comprises a phase of interruption of concreting of the underground site, including a stop of the injection of the concrete and a cleaning of the tube by raising the shutter mobile and pressurized liquid to the feeding site.

Preferably, the cleaning liquid is recycled in the process after decantation and filtration.

According to yet another characteristic of the method of the invention, the height of the column of liquid and / or the pressure of the liquid is adjusted as a function of one or more parameters measured by sensors or calculated, the parameter or parameters including at least one of the following parameters: - the speed of the moving shutter; the position of the movable shutter; the quantity or flow of concrete entering the pipe; the density of concrete penetrating the transport tube; - the viscosity of the concrete penetrating the transport tube; the temperature of the concrete penetrating the transport tube; the temperature of the liquid; the pressure of the liquid.

According to a specific characteristic of the process, the height of the column of liquid and / or the pressure of the liquid is controlled by varying the opening of a valve and / or by varying the flow rate of a pump. a liquid circuit.

According to yet another feature, the conveying tube is cooled by an upward flow of compressed air in a chamber surrounding the delivery tube. Another object of the invention is a concreting installation of an underground site, comprising at least one vertical bore receiving a conveying tube for the transfer of concrete from a feeding site located at an altitude greater than subterranean site to the underground site, characterized in that it further comprises a movable shutter housed in the conveying tube and a liquid circuit for filling the delivery tube with liquid under the shutter and extracting the conveying tube the liquid under the shutter by exerting a vertical counterpoise on said shutter.

According to an advantageous characteristic of the installation of the invention, the liquid circuit is connected to a lower end of the conveying tube. According to a first variant of the installation of the invention, the liquid circuit comprises a conduit for supplying the pressurized liquid housed in a second vertical borehole.

According to a second variant of the installation of the invention, the liquid circuit comprises a conduit for supplying the pressurized liquid housed in a single bore also containing the conveying tube.

[0006] Preferably, the liquid circuit is a closed circuit comprising means for recycling the liquid. According to yet another feature, the bore is provided with a lining defining a cylindrical chamber around the conveying tube in which are disposed detection and measurement instruments.

According to other advantageous features, the installation comprises at least two double-hatch stop drawers, a first of the two stop drawers being surface-mounted on an upper end of the tube supplying the concrete supply. from an injection pump and a second of the two stop drawers being mounted at the bottom of the well on a lower end of the conveying tube, coupled to a concrete return pump. According to a specific variant, the installation comprises, in addition, a third stopper mounted in the gallery downstream of the second drawer and ensuring the distribution of concrete.

According to yet another variant, the liquid circuit comprises at least one pump ensuring the pressurization of the liquid which is fed to the surface, by one or more tanks for the storage and recycling of the liquid.

A complementary feature relates to the structure of the movable shutter which comprises a cylindrical body carrying circumferential ribs whose diameter substantially corresponds to the inner diameter of the conveying tube and provided with an insert detectable by electromagnetic means, d ' an ogive base with a thrust face and a frustoconical head.

The method and the concrete installation according to the invention ensure continuous lubrication of the conveying tube leading to a regular descent, controlled and controlled concrete and subsequent cleaning of the tube using a liquid circuit closed, without risk of spreading or pushing concrete.

The liquid used in the hydraulic circuit thus provides three functions, respectively, retarder of the concrete column, autonomous lubrication of the routing tube during descent and cleaning at the end of concreting. This liquid is preferably water (or an aqueous fluid), which is taken up, sanitized, which provides a substantial saving of charges, simplifies the casting process at the bottom of the well and preserves the environment .

Therefore, the method of the invention is very low water consumption because the liquid circuit is equipped with filtering means and recycling.

Furthermore, the method of the invention minimizes the risk of spreading and leaking liquids or water at the bottom of the well which makes the concreting process particularly clean.

Moreover, the method of the invention limits the risk of segregation of the concrete, to avoid cement deposits and to overcome the use of a slurry.

The concrete installation of the invention is, in addition, self-lubricating because the concrete conveying tube is constantly immersed or in contact with the fresh concrete. The invention also provides for the joint presence of means ensuring the rapid detection and real-time malfunctions and means exerting necessary corrective actions including, partial or total emptying of the transport tube and the rise of the concrete towards the surface in case of refusal of the spoiled.

All the components and parameters of the method and the installation of the invention are, moreover, managed reliably, automatically and centrally from the surface.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become apparent from reading the description which follows, with reference to the accompanying figures and detailed below.

FIGS. 1A and 1B show synoptic views of two embodiments of the installation for implementing the method of the invention, respectively, to a borehole and two boreholes connected in a U.

Figure 2 is a schematic side view of the lower part of the borehole at the underground gallery giving access to storage cells.

Figures 3A and 3B show top and bottom views of an embodiment of the movable shutter used in the installation of the invention.

FIG. 4 represents a detail sectional view of a borehole according to an alternative embodiment of the installation of the invention with the movable shutter.

For clarity, identical or similar elements are identified by identical reference signs throughout the figures.

DETAILED DESCRIPTION OF EMBODIMENTS

Of course, the embodiments illustrated by the figures presented above are given by way of non-limiting examples. It is explicitly foreseen that we can combine these different modes and variants to propose others.

Figures 1A and 1B illustrate a preferred embodiment of the concreting process of the invention with a single drilling installation F (Figure 1A) or two holes Fl, F2 U-connected (Figure 1B) . The method of the invention is more particularly intended for the concreting of an underground site used for the storage of radioactive waste. The underground storage site generally consists of storage cells (not shown) arranged in a network of access and connection galleries located at great depth. The mechanical reinforcement of these storage cells and the different galleries is made by concrete conveyed by means of the installation schematically represented in the figure In the case of concreting at great depth, the context is different from the traditional uses encountered in civil engineering because the routing of concrete spread over a very long period. This does not allow any human intervention which makes the process and installation difficult to manage. The concrete is then directed over a few hundred meters or even several kilometers horizontally.

The solution adopted by the invention is to convey the concrete B using at least one bore in which is housed a so-called routing tube intended to last for several years with frequent periods of intense concreting.

Because the concrete flow rates may be punctually important, depending on concrete campaigns, with flow rates of the order of 60 m3 / h, a malfunction of the installation can cause adverse consequences in the operation of the storage .

The concrete installation according to the invention must therefore meet the following criteria: be simple and durable structure using corrosion resistant materials such as stainless steels, ensure a way of conveying concrete allowing a descent at constant speed so that it does not segregate or that there is a risk of blockage of the drilling does not occur during the descent, be equipped with a detection system to monitor and control the routing of the concrete so as to prevent any malfunctions, have a capacity for rapid commitment of corrective actions to evacuate the concrete and clean the tube that could be obstructed.

The concreting installation of the invention therefore comprises, in the traditional way, at least one vertical drilling F receiving a tube A for the routing concrete B from a feeding site to an underground site at a lower altitude than the feeding site.

The feed site is located near a CB concrete plant (preferably positioned at the surface) and ensures the continuous supply of concrete B of the A routing pipe to the underground site located at great depth.

The tube A conveys, meanwhile, the descent of the concrete column B and is connected to a device for removing the concrete from a lower end of this column to distribute the concrete in the underground site (see Figure 2).

When the process is applied to the concreting of an underground site intended for the storage of waste, the transport of the concrete is ensured up to the disposal cells via the borehole F and the underground galleries via a network of pipes or pipes. conveyors (mobile trolleys or buckets). In order to fulfill the specifications defined above, the installation of the invention furthermore specifically comprises a movable shutter 1 (FIGS. 3A, 3B and 4), for example in the form of shells, housed in the conveying tube A and a liquid circuit L (or hydraulic circuit), intended to control the rate of descent of the concrete B in the tube A by ensuring, on the one hand, the pressurization of the liquid exerting a vertical thrust on the shutter 1 and, on the other hand, the withdrawal of this liquid.

The liquid circuit (or hydraulic circuit CH) is connected to the conveying tube A concrete near the bottom of the well and consists of a closed circuit comprising at least one hydraulic pump PHI, PH2 ensuring the setting pressure and withdrawal of the liquid L. The hydraulic pumps PHI, PH2 are supplied at the surface by at least one tank (or tank) C1, C2 liquid. Additional filtration and / or settling means D coupled to a valve V allow the liquid L to be recycled into the installation, as illustrated by the dashed lines in FIGS. 1A, 1B. The action of at least one hydraulic pump makes it possible to generate the counter-thrust on the shutter 1 in order to balance the system (Jurin tube). This pump can operate in depression to facilitate the descent of the concrete column B as it can operate at high pressure to raise the shutter 1 and all or part of the concrete column B to the surface, if necessary.

A manometer or pressure sensor (pressuremeter) CP, associated with a purge PS (Figures 1A and 1B), is disposed in the underground gallery or on the surface to measure the discharge pressure of the liquid L in the hydraulic circuit CH.

The drill head is adapted to receive a volume of concrete in continuous flow, possibly under pressure.

The concrete conveying device consists of an outer liner C steel (Figure 4) for the protection of the borehole F and the inner tube A for conveying concrete made of stainless steel and ensuring the transit of concrete B. Stainless steel reduces friction, reduces viscosity and minimizes corrosion.

In the case of wear (premature or normal) of the inner tube A routing, it is possible to extract it from the borehole and bring it back to the surface to repair or replace it.

In the embodiment of Figure 1A and as shown in the sectional view of Figure 4, the empty space between the outer wall of the inner tube A of the concrete and the inner wall of the liner C drilling F then delimits an annular or cylindrical intermediate enclosure E in which electromagnetic detection and measurement instruments M are arranged. These instruments make it possible to follow the descent of the concrete B continuously and to make sure of the proper operation of the installation. .

The tube A is cooled by a rising air flow S, possibly compressed, which passes into the annular enclosure E around the outer wall of the tube A and which is taken from an air intake PA connected to the base of tube A (FIGS. 1A, 1B). According to a variant of the installation of the invention illustrated in Figure 4, it is expected to spiral a self-supporting optical fiber P around the tube A routing. This optical fiber monitors the temperature distributed over the entire length of the tube, but also to measure the mechanical deformation of the latter. It is also possible to provide the installation of pressure sensors (not shown) disposed on the outer surface of the conveying tube. These sensors can be arranged at regular intervals every 5 to 10 meters.

The instruments M, P also allow to monitor the kinetics and kinematics of the movable shutter 1, as described below. They thus make it possible to know the progress of the descent of the concrete column B in the tube A and to control the three essential and successive operations of the process which will be described in detail later, namely; the lubrication of the internal concrete pipe, the descent of the concrete column and the cleaning of the pipe after concreting of the underground storage site.

The movable shutter 1 is intended to be introduced into the tube A for routing at the drilling head and is positioned at the top of the liquid column L. This shutter separates the cement phase from the liquid phase (aqueous) L and descends vertically under the weight of the concrete column B. [0045] The movable shutter 1, one embodiment of which in the form of a shell is illustrated in FIGS. 2A and 2B, comprises a cylindrical body 11 provided with circumferential ribs 12 whose diameter substantially corresponds to the inner diameter of the tube, a head 13 and a frustoconical base 14 having a thrust or traction face for the liquid delivered by the hydraulic circuit. The base 14 has, preferably, a beveled profile or ogive to facilitate the descent of the shutter 1 in the tube A. The head 13 has a truncated or truncated face intended to support the base of the column. concrete B.

The ribs 12 in the form of radial fins improve the scraping of the wall of the tube A during cleaning of the installation and ensures an axial retention of the shutter 1 during its descent as well as a stability during the equilibrium of the pressures.

The frustoconical base 14 has an interior cavity 140 optimizing the application of the counter-thrust force exerted on the shutter F by the liquid L under pressure (Figure 4).

According to a variant of the invention illustrated in Figure 4, the body 11 of the shutter 1 is provided with an insert, for example, in the form of a ring G mounted here between the ribs 12, which is electromagnetically detectable by the M instruments previously described. This insert is integrated from a functional point of view into the electronic circuit Y of control-command or supervision of the installation in order to follow the movement of the movable shutter 1 in the tube A of routing as well as the detection of its passage through the stop drawer. The transmission of the detection signal of the insert thus allows the operator to actuate, from the surface, the opening or closing of the valves of the stop spool situated at the base of the bore F.

According to a variant not shown, the insert with electromagnetic properties is, for example, in the form of a ball embedded in the body of the movable shutter 1.

The installation is also equipped with at least two double-hatch stoppers T1, T2. A first stopper T1 is mounted at the surface or at the concrete feed site on an upper end of the delivery tube A. A second stopper T2 is mounted at the bottom of the well on a lower end. of the transport tube, possibly coupled to a PB2 concrete return pump (Figures 1A, 1B and 2). Where appropriate, the installation further comprises a third stopper T3 mounted in the gallery downstream of the second drawer and ensuring the distribution of the concrete to the storage site, as illustrated by FIGS. 1A, 1B. The equipment located at the base of the borehole and, in particular, the stop drawers are sized and adapted to receive the column of concrete under pressure.

If necessary, a complementary filter is mounted at the bottom of the well, in the reception gallery of the concrete, to purify the liquid of the primary hydraulic circuit.

As described below with reference to a preferred embodiment of the installation, the latter is provided with a concrete injection pump PBl surface whose power is about 200 KW. The pump PB2 for the recovery and distribution of concrete is placed in the access tunnel to the disposal cells and has a power of about 400 KW.

The detection system connects the hydraulic pump PHI for pressurizing the liquid, the concreting pump PB1 ensuring the injection of the concrete and the stop drawers T1, T2, T3 with hydraulic control located respectively on the surface. and in the underground concrete receiving gallery. The installation is monitored and controlled with all its components from the surface from a dedicated CO control station.

The control system is automatable and centralized. All the information Y acquired along the concrete conveying tube is stored continuously in a central datalogger. Any sufficiently significant malfunction thus leads to immediate intervention by the watch operator in the control station.

In a first embodiment (Figure 1A), the hydraulic circuit CH (solid line) comprises a liquid supply conduit L housed in a single bore F also containing the tube A conveying concrete B. This duct is then disposed in the vicinity of or around the inner tube A for conveying the concrete.

In a second variant embodiment of the installation of the invention (FIG. 1B), the hydraulic circuit CH (always in solid line) comprises a duct supplying liquid housed in a vertical bore F2 disposed at a distance from the bore Fl in which the concrete conveying tube A is arranged. The liquid pipe of the bore Fl is connected to the lower part of the tube A for conveying the concrete and thus to the bore F1 by forming a double-bore U. In all cases, the wells must be watertight and sufficiently resistant to hold the hydraulic pressure.

The concreting process implemented in the context of the invention with the installation defined above comprise successive steps which will now be described in detail in the following. In a traditional way, this method provides, to convey the concrete vertically from a feeding site located at an altitude higher than the underground site and to the underground site by a continuous supply of concrete a transport tube A disposed within the borehole F and ensuring the descent of a concrete column B and then removing the concrete from a lower end of the concrete column to distribute the concrete in the underground site.

When the underground site is intended for waste storage, the concrete is taken from the bottom of the well from the lower end of this column to transport it to storage cells.

The method of the invention aims to overcome the technical problems generally encountered in such operations. For this purpose, the method consists, more particularly, in initially filling the concrete delivery tube with a liquid L (preferably water) before introducing a movable shutter 1 of the type described above and illustrated by the Figures 2A and 2A.

It is then planned to continuously feed the concrete injection pipe and then exert, during the continuous descent of the concrete column in the conveying tube, a vertical thrust upwards on the shutter which is positioned at the top of the liquid column by adjusting the height of the liquid column and / or the pressure of the liquid in the delivery tube to control the descent of the concrete. The height of the column of liquid and / or the pressure of the liquid is adjusted by withdrawing the liquid at a lower end of the conveying tube by varying the opening of a valve and / or by varying the flow rate. a pump mounted on the hydraulic circuit, in order to control, in particular, the descent speed of the concrete column.

The method of the invention provides for adjusting the height of the liquid column and / or the pressure of the liquid as a function of one or more parameters that are measured by appropriate or calculated sensors. These parameters include at least one of the following parameters: - the speed of the moving shutter; the position of the movable shutter; the quantity or flow of concrete entering the pipe; the density of concrete penetrating the transport tube; - the viscosity of the concrete penetrating the transport tube; the temperature of the concrete penetrating the transport tube; the temperature of the liquid; the pressure of the liquid.

The final step of the process is to take the concrete at the base of the conveying tube to bring it and distribute it in the underground storage gallery where are the cells containing the waste to be concreted.

From his CO control station, the operator is able to detect malfunctions of the installation, to trigger live openings and closures of the drawers, to adjust the flow rates of the pumps and refit the shutter 1 to remove the concrete column from the borehole as quickly as possible.

During the initial step of loading and lubrication, the single borehole or the two U-holes are pre-filled completely with L liquid (phase at rest).

The inner tube A conveying the concrete is constantly lubricated by the liquid L and it is therefore not necessary to use the cementitious slip.

In the hydraulic load phase of the bore F, the trap door Tl stop located on the surface is in the closed position to prevent the flow of concrete.

The shutter trap T2 located at the base of the routing tube A is also in the closed position so that the liquid can not drain into the concrete pump PB1.

At the beginning of the descent of the concrete, the hatch of the stopper T1 located on the surface opens to allow the flow of concrete while the other door closes.

The shutter trap T2, located at the base of the casing, opens so that clean liquid L can pass into the primary hydraulic circuit to ensure against thrust during the steps following. The second step begins with the introduction into the inner tube A for conveying the concrete and from the feed site and, generally, from the surface, the movable shutter 1.

This step is continued by the continuous supply, for example, from the surface and the central CB, the internal concrete conveying tube B gravity or injection pressure using a pump if necessary.

The vertical routing of the concrete is facilitated by the slow descent of the column of liquid in the tube, managed by the activation of the hydraulic pump PHI in depressurization thus causing the suction of the liquid towards the bottom of the tube A and favoring the descent of the shutter 1.

If necessary, the flow rate of the concrete injection pump PB1 is increased to increase the pressure of the concrete column and facilitate its descent into the conveying tube.

At the same time, the pressure of the liquid is adjusted from the surface of the well and its drawing is carried out from the base of the concrete conveying tube A.

From the CO central control station located on the surface, the operator ensures the proper balance between the heights and / or the respective pressures of the concrete column B and the liquid column L and ensures maintain a steady rate of descent of the concrete.

Optical and / or electromagnetic sensors (for example of the type previously described sensors P, M), arranged at the stop drawer T2, detect the passage of the movable shutter 1 whose position coincides with the level phase separation between liquid L and concrete B.

As illustrated in Figure 2, the lower end of the routing tube A is connected to the stopper T2 by means of a welded male flange A2 and A3 collars. Under the shut-off drawer T2 is mounted a receptacle A1 of the movable shutter 1 (shell) provided with a CE lifting angle for the intervention of a forklift (not shown) circulating in the underground gallery of the site .

The passage of the shutter 1 through the drawer T2 then triggers an alarm signal which is transmitted to the control station CO located on the surface and which signals the operator the arrival of the concrete at the base of the tube routing A.

When the movable shutter reaches the base of the transport tube, the operator stops the hydraulic pump No. 1 to stop the withdrawal of the liquid. If necessary, the concrete column is then balanced with the pressure of the liquid. The single-drawer hydraulic control slide drawer T2 (calibrated preferably at 120 bar), which was previously closed to allow the circulation of the liquid, opens to release the concrete which is then poured into a holding tank and / or directly in a tank (not shown) supplying the distribution pump PB2. This stage continues as long as the concrete is lowered and the installation can then operate in steady state, if necessary, for a very long period, taking into account the volumes of concrete required for the concreting campaigns of the storage site. construction is progressive.

The descent of the concrete is ensured continuously thanks to the pressure exerted by the concrete pump PB1 located at the feed site located, for example, on the surface and which is fed by the concrete plant CB.

The double hydraulically controlled stopper Tl located on the surface and the drawer T2 located in the receiving gallery are open to let the concrete.

In the concrete receiving gallery, the PB2 concrete pump coupled to a third drawer drawer T3 hydraulically controlled and double drawer ensures the distribution and selective distribution of concrete in the various galleries and storage cells.

From the CO surface control station, the operator monitors the descent of the concrete by reading and continuous analysis of the control parameters of the concrete column, as defined above and measured along the routing tube A.

The invention provides the possibility of proceeding to a phase of interruption of concreting of the underground site. In this phase, it then stops the injection of concrete and cleaning the transport tube by raising the movable shutter and pressurized liquid to the feed site. When concreting operations of the underground site are completed, it is proceeded to the closure of the access door connecting the drawer T1 to the pump PB1 concrete injection. The stopping of the concreting thus condemns the hatch reserved for the feeding of the routing tube A (hydraulic double-slider stop Tl). The emptying tube is carried out as completely as possible by leaving the concrete column down by simple gravity.

Then, we open the second trap door T2 dedicated to the hydraulic circuit to allow the rise and circulation of liquid L. The trap door T2 located at the bottom of the well is closed thus denying access to the PB2 concrete pump located in the gallery.

The routing tube inside the borehole is then isolated and is ready for cleaning which is provided by the remonstrated liquid under pressure.

The trapdoor of the double stopper valve T2 is then open allowing the liquid to circulate while the hydraulic pump PHI is actuated. The liquid L under pressure raises the shutter 1 with the liquid column from the base of the borehole to the surface. It is possible to add a foam ball to the transport tube to reinforce scraping and to increase cleaning efficiency.

Milt which has deposited on the walls of the transport tube is then raised by the shutter.

At the outlet of the tube, the cleaning fluid loaded with cement and used flows into the settling tank C2 and is cleared by passing through a filtration system D equipped with a particulate filter, a gate valve. guillotine V and the hydraulic pump PH2 which is arranged between the settling tank C1 and the hydraulic pump PHI (see Figures 1A and 1B).

This liquid can then be introduced back into the primary circuit by activating the hydraulic pump PHI.

The routing tube A is then filled with liquid again and is ready for a second concrete campaign. The management of malfunctions of the installation is carried out in the following manner according to characteristic aspects of the method of the invention. Thus, in the event of premature heating of the concrete, the drilling and, more particularly, the conveying tube, can be cooled by an air flow, possibly compressed, directed from below upwards so as not to disturb or alter the conventional ventilation circuit / cycle of underground installations. The descent speed of the concrete column can be accelerated by opening the stop drawers and / or by operating the hydraulic pump PHI.

In case of slowing of the concrete in the transport tube (for example, due to the formation of aggregate nests), accumulation or blockage of the concrete, the immediate actuation of the hydraulic pumps allows a recovery fast pressurized liquid in the tube. The rise of the liquid allows a more efficient breaking of the concrete if it concentrates the aggregates.

Conversely, in the case of excessively large concrete flow, the process can be slowed down by closing the stop drawers and / or by operating the hydraulic pump No. 1. The decision to stop the process and, in particular, the routing of the concrete, can be taken by the operator very quickly from the information and signals sent by the detection and measurement instruments integrated into the borehole.

From the CO surface control station, the operator can then proceed with the drain as complete as possible of the routing tube A and recover the concrete B in a tank disposed in the gallery. This action leads to an optimal lightening of the concrete column thus allowing the hydraulic counter-thrust system to be more efficient.

In case of blockage of the concrete in the conveying tube (for example, if there is a build-up of aggregates in the tube), the pressurization of the liquid by activation of the hydraulic pump PHI allows to go up the concrete column in whole or in part reactively and quickly. In this case, it is possible to actuate the concrete pump PB1 in addition to the upward thrust exerted by the liquid column to facilitate its ascent of the concrete along the tube.

The unblocking of the concrete column is carried out from the bottom upwards and not in the opposite direction which would lead to a detrimental clamping of the concrete in the conveying tube.

The dimensional characteristics mentioned below correspond to a preferred embodiment of the installation for an implementation of the concreting process of the invention under the following conditions. The injection of a density concrete 2,4 with a flow rate of 25 m / h in a concrete conveying tube 506 meters deep and 152.5 mm internal diameter.

Under these conditions, the descent speed of the concrete column is 60 km / h and the column mass of 21.6 tons for a volume of 9 m ³ . The static pressure at the base of the borehole is 120 bar.

The installation comprises the following main equipment:

^■ a PB1 concrete pump equipped with two motors of 160 kW (this equipment makes it possible to obtain a maximum hydraulic pressure of 290 bars corresponding to a pressure of 200 bars in the concrete), ^■ a PHI water pump equipped with a a 150 kW motor used as a counter-thrust generator and as a means of cleaning pipes,

^■ a T1 hydraulically operated spool rated at 130 bar,

^■ a PA compressed air intake at 6 bar,

^■ 30m liquid C1, C2 (water) tanks, ^■ high pressure metal pipes (stainless steel) with a diameter of at least 120 mm and a thickness of 8.8 mm.

The inner diameter of the conveying tube A is between 120 mm and 200 mm and is preferably 152.5 mm with an outside diameter of 177.8 mm. The inside diameter of the liner C of the bore F is 200 and 300 mm and is preferably 224.4 mm with an outside diameter of 244.5 mm. In this context, the intermediate cylindrical space intended to house the M, P control and control instruments is therefore 46.6 mm.

The linear mass of the routing tube A stainless steel is 52.12kg / m and that of the liner C (also stainless steel) of 59.57 kg / m.

The pressure of the liquid L (for example water) in the borehole increases by 1 bar every 10 meters. For a water column of 500 meters, the pressure is therefore 51 bar taking into account an atmospheric pressure of lbar.

Claims

claims

1. Method of concreting an underground site comprising the vertical conveyance of a concrete from a feeding site located at an altitude higher than the underground site to the underground site by a continuous supply of concrete (B) of a tube of routing (A) between the feed site and the underground site, lowering a concrete column (B) in the conveying tube and taking the concrete from a lower end of said concrete column to distributing the concrete in the underground site, characterized in that initially fills the delivery tube (A) with a liquid column (L) and a movable shutter (1) positioned at the top of the column of liquid, is exerted then, during the descent of the concrete column in the conveying tube, a vertical counter-pressure on said shutter by adjusting the height of the liquid column and / or the pressure of the liquid in the conveying tube in order to to control the desc from the concrete column.

2. Method according to claim 1, characterized in that the height of the column of liquid and / or the pressure of the liquid is adjusted by withdrawing the liquid (L) at a lower end of the conveying tube (A).

3. Method according to claim 2, characterized in that it stops the drawing or withdrawal of the liquid when the movable shutter (1) reaches the base of the conveying tube (A).

4. Method according to one of the preceding claims, characterized in that the continuous supply of concrete (B) is made by injection of pressurized concrete from the surface at the latest as soon as the concrete column reaches the base of the tube ( AT).

5. Method according to one of the preceding claims, characterized in that it comprises a phase of interruption of concreting of the underground site, including a stop of the concrete injection and cleaning the tube routing (A) by raising the movable shutter (1) and the liquid (L) under pressure to the feed site.

6. Process according to the preceding claim, characterized in that the liquid (L) is recycled after decantation and filtration.

7. Method according to one of the preceding claims, characterized in that the height of the column of liquid and / or the pressure of the liquid is adjusted according to one or more parameters measured by sensors or calculated, the parameters including at least one of the following parameters:

the speed of the moving shutter;

the position of the movable shutter;

the quantity or flow of concrete entering the pipe;

the density of concrete penetrating the transport tube;

the viscosity of the concrete penetrating the transport tube;

the temperature of the concrete penetrating the transport tube;

the temperature of the liquid;

the pressure of the liquid.

8. Method according to one of the preceding claims, characterized in that the height of the column of liquid and / or the pressure of the liquid is controlled by varying the opening of a valve and / or by varying the flow rate. of a pump of a hydraulic circuit.

9. Method according to one of the preceding claims, characterized in that the cooling tube (A) is cooled by an upward flow of compressed air (S) in a chamber (E) surrounding said delivery tube ( AT).

10. Concrete installation of an underground site, comprising at least one vertical drilling (F, Fl, F2)) receiving a tube (A) conveying concrete (B) from a feeding site located at a higher altitude at the underground site until underground site, characterized in that it further comprises a movable shutter (1) housed in the conveying tube (A) and a hydraulic circuit (CH) for filling the tube with a liquid (L). transporting under the shutter (F) and extracting from the delivery tube (A) the liquid (L) under the shutter by exerting a vertical counterpoise on said shutter.

1 1. Concreting installation according to the preceding claim, characterized in that the hydraulic circuit (CH) is connected to a lower end of the tube (A) conveying the concrete.

12. Concreting installation according to one of claims 9 or 10, characterized in that the hydraulic circuit (CH) comprises a conduit for supplying the liquid (L) under pressure housed in a second vertical bore (F2).

Concrete installation according to one of claims 9 or 10, characterized in that the hydraulic circuit (CH) comprises a liquid supply duct (L) under pressure housed in a single bore (F) enclosing the tube ( A) conveying the concrete.

14. Concreting installation according to one of claims 9 to 12, characterized in that the hydraulic circuit (CH) is a closed circuit comprising means for recycling the liquid.

15. Concreting installation according to one of claims 9 to 13, characterized in that the borehole is provided with a liner (C) delimiting a cylindrical enclosure (E) around the tube (A) conveying in which are arranged detection and measurement instruments (M, P).

16. Concreting installation according to one of claims 9 to 14, characterized in that it comprises at least two stop drawers (T1, T2, T3) double-hatch, a first (Tl) of two drawers d stopper is surface-mounted on an upper end of the tube (A) providing the supply of concrete from a injection pump (PB1) and a second (T2) of the two stop drawers being mounted at the bottom of the well on a lower end of the conveying tube (A), coupled to a concrete pump (PB2).

17. Concreting installation according to the preceding claim, characterized in that it further comprises a third stop spool (T3) mounted downstream of the second spool (T2) and ensuring the distribution of the concrete (B).

18. Concreting installation according to one of claims 9 to 16, characterized in that the hydraulic circuit (CH) comprises at least one pump (PHI, PH2) ensuring the pressurization of the liquid (L) which is supplied with surface by at least one or more tanks (C1, C2) for storing and recycling said liquid.

19. Concreting installation according to one of claims 9 to 17, characterized in that said movable shutter (1) comprises a cylindrical body (11) carrying circumferential ribs (12) whose diameter substantially corresponds to the inside diameter of the tube routing (A) and provided with an electromagnetically detectable insert (G), a base (14) with a warhead having a thrust face and a frustoconical head (13).