FR2680201A1 - METHOD AND DEVICE FOR OPERATING AN UNDERGROUND DEPOSIT BY A TUNNELIER. - Google Patents

Abstract

The process is intended for the exploitation of an underground deposit whose extraction is made difficult by the radioactive and / or toxic nature of the deposit and / or by the geotechnical conditions. By injection of hydraulic binder and / or by freezing, a sealed box (C) confining all or part of the deposit is formed and the deposit is optionally drained; one crosses right through the deposit by direct digging of a first tunnel using a tunnel boring machine; the tunnel boring machine is turned over after crossing the deposit and a tunnel adjacent to the first is dug directly, and so on; if the deposit contains a radioactive, dangerous or toxic product, the extracted material is reduced to pulp as it is cut and it is removed by hydraulic transport.

Description

METHOD AND DEVICE FOR OPERATING UNDERGROUND DEPOSIT

BY TUNNELIER

  The invention relates to methods and devices for operating underground deposits of a nature such as

  the cost of extraction per ton goes to the background.

  The invention finds a particularly important application in the extraction of ores or substances whose toxicity or radioactivity are such that it

  it is not possible to implement the conventional processes

  ques of mining, especially when geotechnical problems are added to radioactivity or

toxicity.

  As a particularly representative example, one can cite the exploitation of uranium deposits with very

  high content, o the level of radioactivity excluded

  traditional methods involving the presence of staff

  permanently on the cutting face but o a cost of ex-

  high traction per tonne is not prohibitive because it is counterbalanced by grades up to 100 kg per tonne,

or more.

  A similar problem arises in the case of deposits with a very high content of a product of high market value, relatively thick, but occurring under particularly difficult geotechnical conditions, such as under very high lithostatic and hydrostatic pressures.

  raised in deconsolidated land.

  Mention may also be made, as an application of the invention, of removal, for decontamination and / or

  safe storage of hazardous substances

  not necessarily of market value but

that it is imperative to eradicate.

  The latter case can for example be encountered in the event of contamination of the polluted subsoil of a nuclear installation.

  The invention therefore aims to provide a pro-

  yielded to the exploitation of underground deposits, the extraction of

  tion is made difficult by the radioactive and / or toxic nature of the deposit and / or by the geotechnical conditions, when the market value of the deposit and / or the necessity

  absolute to extract it make the cost of the operation secondary

ration for each tonne extracted.

  To this end, the invention notably proposes a pro-

  assigned according to which: by binder injection,

  hydraulic and / or by freezing, a waterproof box

  ending all or part of the deposit and we eventually drain-

  lie the deposit; we cross right through the deposit by direct digging of a first tunnel using a

  tunneling machine; we return the tunnel boring machine after crossing the gi-

  and a tunnel adjacent to the first is directly dug

  mier, and so on; and, if the deposit contains a

  radioactive, dangerous or toxic product, the material is reduced

  material extracted into pulp as and when slaughtered and

  it is removed by hydraulic transport.

  In the case of difficult terrain, presenting a risk of landslides, the gallery is paved with segments immediately behind the tunnel boring machine. Once a tunnel has been completely constructed, it can be immediately backfilled

  to participate in absorbing the thrust of the terrain.

  Depending on the nature of the difficulties encountered in

  operation, the process will be more or less complex.

  When the difficulties encountered are essential-

  geotechnical in nature (lithostatic pressures and

  hydrostatic), causing significant water inflows

  aunts, the creation of a barrier by covering with segments supported by gaskets, solves the problem In the case of materials

  radioactive, the above measures already deviate from many

  serious problems: gamma radiation of external origin

  is absorbed by the concrete of the segments and the skirt of the tunnel

  link The tunnel overpressure reduces radon entry Hydraulic transport can

  take place through a pipe embedded in a protective base

  tion against the gamma radiation of the extracted material.

  The conditions of use of the tunnel boring machine, for the implementation of the method according to the invention, are extremely

  unusual and seem at first sight to be economic nonsense

  mique A tunnel boring machine is in fact planned to dig excavations.

  Very long lines in continuity On the contrary, the process according to the invention involves long periods of inactivity after the completion of each tunnel. However, this consideration becomes secondary when the market value of the material extracted or the absolute necessity of eliminating it imposes '' perform the extraction, because none of the known, more economical solutions is applicable in the cases

mentioned above.

  The invention also provides a device

  of underground deposit including a tun-

  nelier with punctual attack by telescopic arm excavator

  swivel spike, separable into at least three long sections

  longitudinal, carrying a grinder and a pulverization pump

  eg material slaughtered with a view to sending the pulp in a hydraulic transport pipe and having, in its

  rear section, a device for positioning you-

tunnel lining evenings.

  The tunneling machine, for the extraction of strong ores -

  radioactive, has a skirt of sufficient thickness to reduce the intensity of the radiation It is intended to

  can be returned to a room after crossing

  full of the deposit, either by rotation of 1800 around a vertical axis, or by dismantling then reassembly The three sections can themselves be divided into sectors of about 1200 each, to facilitate the operations of

transfer in the latter case.

  The invention will be better understood on reading the

  description which follows of a particular embodiment,

  given by way of nonlimiting example The description is

  refers to the accompanying drawings, in which:

  Figure 1 is a perspective block diagram

  tive, showing the operations for preparing a fraction of the deposit, before slaughtering; Figure 2 is a schematic sectional view showing the digging of a first horizontal tunnel through the deposit; Figure 3, similar to Figure 2, shows the juxtaposition of the tunnels drilled, coated and filled during operation; Figure 4 is a schematic view, in section

  in a vertical plane, showing the main constituents

  piping of a tunnel boring machine constituting a particular embodiment of the invention; Figure 5 is a cross-sectional view of the coated tunnel at the rear of the TBM, when implementing the method according to a particular embodiment

of the invention.

  The process which will now be described can in particular be used for the exploitation of an underground deposit of very high grade uranium ore, in the form of an elongated vein, in a deconsolidated rock, under

  very high lithostatic and hydrostatic pressure.

  As an example of a deposit presenting these ca-

  characteristics, we can cite that of CIGAR LAKE, SASKATCHEWAN, Canada, which has a content of 100 kg per tonne on average, allowing exploitation at a very fast rate

  low of the order of 200 tonnes per day The rock receives

  health is a deconsolidated sandy-sandstone, with abundant water inflows The exploitation must be done under pressure

  lithostatic of the order of 80 bars and a hydro-

  static around 45 bars The deposit has an elongated shape, with a width of around a hundred

of meters.

  The first operation to be carried out, before attacking the

  deposit, aims to form, around a longitudinal fraction

  the deposit, a watertight box that it will be possible to

  drain, the walls of which consist of conso-

  covered by freezing and / or injection of cement slurry, each caisson enveloping the deposit as close as

  possible, practically at a distance of a few meters.

  To do this, first of all, infra-

  conventional structures for access to the deposit, including the depth

  deur is around 450 meters in the case of CIGAR LAKE We dig the access and aeration wells and we set up the energy, ventilation, extraction, etc. installations, then we dig the horizontal galleries to access the deposit as well as horizontal infra-structure galleries Among these infrastructure galleries, at least two 12 extend in the direction of elongation of the

  deposit, roughly parallel to the edges of the latter.

  They can be roughly at the upper level of the gise-

  Another 14 at least is a few meters above

below the deposit.

  Two parallel cuts 16 are then dug from the gallery 14, at distances which will depend on the nature of the ground but will generally be of the order of

the ten meters.

  From the different galleries 12 and 14 and re-

  sections 16 are then drilled vertical holes 18 intended to receive the freezing beams and possibly

  cement pouring lances The green holes

  ticals drilled from the cuts 16 which cross the gi-

  In any case, will be used for freezing.

  At the end of these operations and the freezing at

  from two cross-sections, we see that we have created a case

  sound surrounding a section of the deposit This box, the periphery of which is shown in C in FIG. 2, can then be drained, its central part not being frozen.

  that part that the extraction will take place.

  Felling inside the box is carried out by repeating the same sequence From the galleries 12 on

  digs two inclined planes 20 for access to recovery chambers

  turning 22, through the frozen rock These chambers of

  turning 22 (figure 2) are formed at a distance from the mine-

  rai itself, so that the level of radioactivity remains acceptable there for human intervention A tunnel boring machine, such as that which will be described later, is assembled in one of the turning chambers 22, located just above

  from the base of the deposit The tunnel boring machine is then used

  glass and directed, horizontally or obliquely with respect to the gallery 12, towards the other turning chamber It crosses the curtain of sterile material, then the deposit to the opposite turning chamber 22 In this chamber, it can be checked and renovated, by replacing the elements most susceptible to wear or breakdown It is then moved back on the inclined plane to the gallery 12 The first tunnel is backfilled A new inclined plane is formed up to a turning chamber located immediately at side of the previous The inclined plane and the previous room are backfilled for example using

  materials felled to form the new inclined plane.

  The TBM can then be advanced to dig a second tunnel. Once all the successive tunnels in the section

  at basic level B (figure 3) were dug and then

  layed, lower inclined inclined planes are made to successively process the upper levels

of the deposit.

  Thanks to the prior containment in a watertight box, the problems of water coming in are eliminated.

  line the tunnel as the tunnel advances

  tie by segments, to provide joints between successive rings and to use a watertight tunneling machine, the effect of

  the freezing is completed and allows to work in ter-

  rain fragile, at great depth, with strong ve-

bare of pressurized water.

  While a caisson is being treated in this way, the caisson

  following can be prepared by optional lengthening of the

  lines 12 and 14, digging of cuts 16 and freezing

  and / or injection to form a new box.

  We will return later to the part of the process concerning the actual attack on the ore. The tunnel boring machine used can have the basic principle shown in FIG. 4, comprising three sections

  longitudinal 28, 30 and 32 can be assembled and disassembled.

  Each of these sections may itself be designed to be removable into several angular sectors, three for example, so as to reduce the size and weight of the components that cannot be separated during transport. For the same reason, a compact tunnel boring machine will generally be used, having a reduced skirt diameter, for example of about four meters Each of the sections may also have

  a short length, for example around 1.50 m.

  The front section comprises a skirt and constitutes a kit which can be oriented by jacks 34, closed at the rear by a watertight bulkhead provided with observation windows (this bulkhead may as well belong to the middle section 30) The section 28 carries an apparatus for felling with punctual attack, constituted in the case illustrated by an excavator with telescopic arm 36 terminated by a driving crown 38 which can be brought projecting with respect to the section 28 The excavator is doubled by a block breaking device 39, allowing if necessary reduce them to a

  size of a few centimeters and an injection device

  tion of water under high pressure The ore mined is thus

  brought to the state of fragments of sufficiently small size

  ble to be driven by a conveyor, as we will see

further.

  The front section 28 is advantageously provided for

  receive a removable diaphragm 41, allowing, after re-

  pull telescopic arm 36, isolate the device

  slaughtering of the working face to authorize an intervention

  mechanical tion This diaphragm can be connected to a helmet

  40 security provided at the upper part of the section.

  The median section 30 constitutes the pusher It comprises

  consequently wears, inside the skirt, a

  row of hydraulic cylinders 42, twenty four for example, whose plunger 44 is intended to bear on segments already in place The section also carries an ore recovery conveyor, consisting

  in the case illustrated by an oblique extraction screw 46.

  This screw raises the fragments in a crusher 48 which reduces them to a particle size sufficiently small to

  allow transport in pulp A mixer device-

  circulation pump-feeder 50 takes up the crushed ore and brings it, through a non-return valve 52, to the inlet of a tube 54 for connection with a transport pipe The central section 30 may also contain a hydraulic power station 56 providing the pressurized fluid required for the operation of the cylinders, the pump excavator and possibly the screws

  transport, crusher and pump.

  The rear section 32 also includes a skirt

  seal 58 intended to slide around the last you-

  evening in place and sealing It can also

  contain a segment erector, which will not be described because it can have a constitution

classic.

  In the illustrated embodiment, the erector

  is planned to set up successively, after re-

  traction of the divers 44, the segments 62 brought by a

  64 hoist carried by a beam fixed to the crowns of you-

  evenings as you advance Les voussoirs peu-

  wind have a provision of the kind shown in figure 5,

  that is to say, include five segments, properly speaking,

  numbered from 1 to 5, a key 68 and two counter-keys 70.

  The hoist can be provided to also install sections 72 of slab, each section having a length equal to that of a segment, intended to constitute a flat floor and to delimit passages One of these

  passages can receive a mid-pipe 74

  nerai, connectable to a telescopic tube 76 for connection to the tube 54 Other passages 78 may constitute technical channels, for example for receiving cables.

  Depending on the nature of the ore to be extracted, pre-

  more or less important additional guarantees are

  In particular, we can interpose between you-

  evenings of a crown or halo, between successive crowns

  and between the last crown and the skirt 38, a tight seal

  with water, to avoid infiltration and, in the event of a uranium mine, invasion of the tunnel coated with radon dissolved in water A second seal, by a

  lead sheet, can be provided to absorb the

  Gamma ment coming from the host rock, with which there is in no case direct communication. Injection holes 80 can be provided in the segments in

square.

  An airlock is advantageously provided at the entrance of the gallery, in the sterile rock This allows to put the gallery in overpressure and to further thwart the invasion

by radon from the ore.

  During the advance of the tunnel boring machine, the command, except in the event of an incident, does not require the presence of personnel inside the tunnel A video camera can be provided in the central section to film the working face The personnel can stay in the

  turning chamber The presence of personnel is not

  only to lay the segments, at the end of an advance corresponding to the length of the segments This phase lasts less than an hour by post It is carried out while the personnel is protected by the crowns of

  segments already in place and by the steel of the skirt of the tunn-

  link Segments of about thirty centimeters thick

  This gives satisfactory protection The steel pipe contained in slab 72 provides protection against the radiation of the ore in pulp entrained by

  water in tubes 42 and 44 and line 74.

  Each intervention of the TBM is of short duration, a maintenance carried out at each passage in a

  turning chamber makes the risk of breakdown very low.

  ble If necessary, however, the diaphragm of the

  front section can be set up quickly and mechanically, under the supervision of a worker who remains in the middle section The diaphragm then isolates the compartment contained in the front section of the working face After decontamination of the equipment and suction of the radon contained in the compartment, an operator can enter this compartment through a watertight door

  provided in the partition and perform the necessary intervention

  to be. When it comes out of the ore, the TBM crosses

  a sterile part before arriving at the return chamber-

  The sterile slaughtering already causes the front structures and the skirts to be cleaned. This cleaning can be

  supplemented by water decontamination.

  Once the TBM is in the return chamber

  We turn it around 1800 to drill a new tunnel in the opposite direction. Turning can be done in a simple way, by providing a turntable in the turning chamber. Turning can also be done by dismantling in sections, then reverse reassembly. As

  example, we can indicate that a tunnel boring machine of four meters

  very in diameter with punctual attacks by diagonal crown

  mantée easily allows, depending on the terrain, a slaughter of 10

  tonnes per hour and a feed speed of 0.20 m / hour.

  The slab sections may themselves be two and a half meters wide and receive a pipe from it

  transport of one hundred and fifty millimeters in diameter.

  The strict stacking of circular tunnels leaves about 9% of the deposit in place.

  slaughter beats an area greater than the tunnel section-

  tying and overcrowding is enough to exploit the

  deposit almost completely.

Claims (8)

  1 Method of operating an underground deposit by tunnel boring machine, characterized in that: the deposit is traversed right through by direct digging of a first tunnel using a tunnel boring machine; we turn the tunnel boring machine after crossing the deposit and we directly dig a tunnel adjacent to the first one, and so on; and, if the   deposit contains a radioactive, dangerous or toxic   1 O that, the material extracted into pulp is reduced as and   measure of the felling and it is evacuated by hydraulic transport   than. 2 Method according to claim 1, characterized in that the tunnel is coated with crowns of segments behind the TBM.   3 Method according to claim 2, characterized in that the joints are joined by watertight joints   between them and with a TBM skirt.   4 Process according to any one of the claims   previous tions, characterized in that the tunnel is isolated   through an airlock and the tunnel is put under overpressure.   Process according to any one of Claims 2 to 4, characterized in that the extracted material is removed by hydraulic transport in a pipe at a   retractable tube (76) provided in the TBM and sections   driving lessons (74) contained in slabs (72) placed in place on the base segments.   6 Method according to any one of the claims   tions above, characterized in that after crossing the deposit, the tunnel boring machine is turned over on a turntable in a turning chamber (22) or by dismantling then reassembly.   7 Device for the exploitation of underground deposits   rain, comprising a tunneling machine with punctual attack by excavator with adjustable telescopic arm, separable into at least three longitudinal sections (28,30,32), carrying a   crusher (48), a pulping pump for the slaughtered material   you and sending in a hydraulic transport pipe (42,44,74) and a device for setting up segments (62) for lining the tunnel.   8 Device according to claim 7, characterized in that the front section (28) contains the excavator and is separated by a watertight partition from the middle section (30) which comprises a lifting conveyor, the crusher (48) and the pump and in that the rear section (32) contains   a prefabricated segment erector.   9 Device according to claim 7 or 8, charac-   terized in that the median section contains a ring of hydraulic passage cylinders (42); an ore recovery conveyor (46) to the crusher (48), said pump and   a telescopic tube (54) for connection with said pipe.   Device according to claim 7, 8 or 9, characterized in that the front section (28) is designed to receive a diaphragm and is separated from the middle section by a bulkhead.