FR2623220A1 - METHOD AND DEVICE FOR LOCALLY BREAKING A LAYER OF ICE IN THE COLD SEA - Google Patents

Abstract

Method and device for locally breaking a layer of ice in cold water, from a structure caught in the ice or submerged under the ice; from this structure, the layer of ice is subjected to a perpendicular thrust so as to put this layer in bending and the thrust and bending are increased until cracking and rupture; for this, a submerged machine or a submerged or emerged part of a structure is provided with a protuberance 3 adapted to rest on the ice and transmit a vertical thrust to it through a calibrated bearing surface. Application to submarines and platforms installed at sea.

Description

The invention relates to a method and a device for breaking down

locally a layer of ice in

cold waters.

  The problem posed by the Applicant is in particular that of a submersible craft which, being immersed under a layer of ice whose thickness can reach a value of the order of one meter, must be able to break the ice at above him to emerge. The problem arises, albeit under different conditions, for facilities such as off-shore platforms or bridge piers that have a

  immersed part, so taken under the ice at certain

  of the year, since the ice must be broken

  for example to protect the structure or to

visit the foundations.

  The process which is the subject of the invention is characterized in that in the zone where it is desired to provoke

  the break, the ice is subjected to a perpendicular thrust

  In this way, the ice layer is flexed and the thrust and flexion are increased to failure. In the case of a submarine, or an installation with a submerged floating part, the directed thrust of

  bottom up is produced by the resulting hydrostatic force

  so much of a proper discharge of ballasts.

  The invention also comprises the device

  for the implementation of the process, a characteristic device

  by a protuberance that can take the form of a mast, whose upper end will come to rest on the face

bottom of the ice layer.

  This protuberance or mast can be retractable

or fixed.

  In the case of a submarine, the mast will generally be

  retractable, consisting of a telescopic system

  sting so that when the mast is out of action, it -2- is completely erased in the hull without leaving any protrusion that would be detrimental to good behavior

hydrodynamics of the submarine.

  The description that follows, next to the drawings

  annexed, given by way of example, will make it possible to

  take how the invention can be realized.

  Figures 1 to 6 are diagrammatic views

  the various stages of implementation of the inven-

  in the case of a submarine navigating under a

of ice.

  Figure 7 shows in section, on a larger scale,

  an embodiment of a telescopic mast, in the retracted state.

  Figure 8 shows the same mast deployed.

  Figure 9 is a graph illustrating the variation

  the force exerted by the mast to break the ice, depending on the thickness of the ice, for different

diameters of the mast.

  Figure 10 is a cross-section of the sub-section

  with a particular embodiment of a secondary mast.

  re. FIG. 11 shows the application of the invention in the case of a platform whose foundation rests

on the bottom of the sea.

  Figures 12 and 13 relate to the case of a platform

floating form.

  FIGS. 14 and 15 show two variants of application of the invention & marine platforms, variants in which the force exerted by the mast to

  breaking the ice is directed up and down.

  In Figure 1, we see in 1 a submarine or submarine craft, civilian or military, inhabited or not, which

sails under a layer of ice 2.

  In FIG. 2, this machine initiates a movement of

  mounted by draining the ballasts to come to the con-

tact of the ice to break.

  A first mast 3 which is the breaking mast proper-

  so-called main mast is deployed on the kiosk

  or massive 4 of the machine, 'and a second mat 5, which we call-

  - 3 - lera the secondary mast, is also deployed towards the stern of the machine to give a support on the ice and to protect the stern organs which are fragile. The ballasts are organized in such a way that the upward buoyancy effort has its result located near the main mast but slightly offset on the side of the secondary mast. This arrangement makes it possible on the one hand to obtain the maximum force available for the main failure mat, on the other hand

  to obtain the longitudinal stability of the machine.

  In Figure 3, we can see that the machine has

  approaching the ice while climbing under the effect of force

  ascensional created by deballasting.

  In FIG. 4, the contact was made, as well by the main mat 3 as by the secondary mat, and

  the force exerted by the main mast on the layer of ice

  this puts it in bending more and more strongly.

  In FIGS. 5 and 6, the ice is broken and

  the massif is in emergence, which is the result sought.

  The emersion could be continued until

  level of floatation, depending on the size of the

lastage realized.

  In the embodiment shown in FIGS. 7 and 8, the main mast and the secondary mast are

  each consisting of a telescopic system.

  In the illustrated example, this system comprises two elements, namely a fixed cylinder 6 and a movable piston 7

  in this cylinder and constituting with it a hydraulic cylinder

  the power of which is sufficient to balance the buoyancy exerted by the submarine and whose

  the race is sufficient to take into account irregularities

  on the underside of the ice cover. This jack is preferably double-acting to ensure the return to the erased position in the hull of the submarine. The cylinder 6 is connected at its ends to pipes 8, 9 provided with valves 10, 11 with three positions for connecting these pipes to the supply of pressurized liquid.

or emptying.

  At the top of the piston rod is a pad 12 serving to support under the ice layer and which may be simply circular in shape. Under this pad 12, is attached a sleeve 13 which can slide in a fixed casing 14 provided with support rings 15, 16 for

a good guide of the shirt 13.

  The casing tube 14 is fixed on the one hand to the outer hull of the submarine 17, and on the other hand to

  a flange 18 on the wall or the inner shell 19.

  The whole is arranged so that in the retracted state, the outer surface of the pad 12 is flush with the hull

outside without harmful projection.

  The liner 13 protects the piston rod against

  actions of the ice. On the other hand, the whole of the

  13 and the envelope 14, maintained by the support rings 15 and 16 provides a system offering greater resistance to lateral forces. These lateral forces can be caused by the inclination of the underside of the ice, or by the non-verticality of the main mast

due to the attitude of the machine.

  It is easy to understand the operation of the

  tif. Starting from the retracted state shown in FIG. 7 to deploy the mat, the valve 10 is operated in order to admit the pressurized liquid beneath the piston 7 and the valve 11 to empty the opposite face of the said piston. The mat then unfolds as the watch shows

Figure 8.

  The blocking of the deployed mast will be done simply by

  valves 10 and 11, which will allow, during the deballasting period, the continuous measurement of the forces applied under the ice by the main mat (and also by

  the secondary mat) by simply reading the heat pressure

  hydraulic inside the cylinder 6.

  This main locking system is doubled by a mechanical type locking system that will be implemented after deployment of the mat, but will become effective only in the event of a drop in hydraulic pressure, for example -5-

because of leaks.

  Such a system was figured in 21. It can

  latches 22 movable transversely to engage in openings on the sleeve 13 to block it. When we want to retract the mat again, simply put the valve 10 in the empty position, and place the valve 11 in the feeding position,

  after having unlocked the mechanical locks 22.

  The curves of FIG. 9 have been plotted with different diameters of the support pad 12, diameters equal to 0.5 m, 1 m and 2 m, respectively. The thicknesses of the ice layer in meters were plotted on the abscissa and the meganewtons required for

  cracking of the ice sheet were carried

  born. These curves show that it is advantageous to reduce the application surface of the force, that is to say the surface of the support pad 12, to crack a given thickness of ice by developing such a limited effort than

  possible; or corollary, to crack a thick

  ice cream as large as possible by developing

a given effort.

  Figure 10 shows a particular embodiment of the secondary mat which, instead of being constituted by a single m & t, consists of two meats 5a, 5b disposed in the same transverse plane and divergent. This has the advantage

  to provide with the main mast a tripod system

  improving the transverse stability of the machine by

ice.

  Figure 11 illustrates another application of the invention. It shows a platform 25 which rests on the bottom of the sea by a foundation 26 whose part

  submerged is under the ice cover 2.

  To break the ice and limit or eliminate

  the efforts exerted by it on the structure or for

  to visit the foundation, we can divide

  this one of the mats 3 of pressure of the ice. In this application, it is not necessary that the mats

  be telescopic. They can be deployed permanently

  nence, as in the embodiment shown in Figure 11, where each mat 3 is supported by a capacitor 27 movable in a fixed cylinder 28. In this case, the set consisting of mats and mobile capabilities, will be

  actuated by a simple Archimedes effect resulting from the

  water storage stored in the capabilities 27, without the need to create a seal between these capabilities 27

  and the cylinders 28. The deballasting of water in

  mentioned, as well as the subsequent deballasting to ensure

  the return to the initial position, are done with the help of a system

  30 of tubing 30 having flexible portions 29, and connected to non-illustrated pumps, installed on the

platform.

  Alternatively, according to the non-embodiment

  represented, the mobile capabilities 27 can be raised

  by piston effect, using the water sent under

  pressure in the sub-adjacent portion of the cylinders 28.

  In this case, it is appropriate to ensure

  mobile capabilities 27 and cylinders 28.

  The right-hand part of Figure 11 shows the

  at rest and the left part shows the position

to break the ice.

  Figures 12 and 13 relate to the case of a platform

  floating form 25 attached by mooring lines 31 which are anchored on the seabed. A platform of this kind comprises ballasts whose filling or emptying

  allow to adjust the height of the immersed part.

  On it we can distribute mats 3 that can be fixed or deployable thanks to a telescopic system similar to that which has been described with reference to the figures

7 and 8.

  Figure 12 shows the platform 25 with a submerged base under the ice layer that has formed on the surface of the water. When we want to break this layer, we deballaste, after deploying the mats 3, if they are

  telescopic. Deballasting produces an ascending force

  And the masts come to put pressure on the ice

  and break it as explained previously.

  Alternatively, it is possible to equip the floating platform 25 with deballastable chambers individually, as in the case of the fixed platform, shown below.

gure 11.

  An additional provision, with the attack of

  the ice by an effort directed up and down is

shown in Figures 14 and 15.

  Figure 14 shows a fixed platform 25 repo

  on the bottom of the sea by a foundation 26 and

  the submerged part is under the ice layer 2.

  To break this layer, we deploy the mats 3, fixed in the emerged part 40 of the platform. The masts 3 act as telescopic cylinders exerting vertical forces from top to bottom, breaking the ice layer locally and thus protecting the platform from

ice effects.

  FIG. 15 shows a floating platform 25 attached by primers 31 anchored to the sea floor. The masts 3 fixed in the emergent part 40 of the platform make it possible to exert vertical forces from top to bottom, by ballast filling and controlled immersion of the structure. The masts 3 can be fixed or deployable thanks to a telescopic system similar to

  that which has been described with reference to FIGS. 7 and 8.

  It goes without saying that the modes of

  described were given only as examples, and that they could be modified, in particular by substituting technical equivalents, without

framework of the invention.

  For example, the hydraulic cylinders described for

  could be replaced by cylinders of different types,

in particular mechanical cylinders.

  On the other hand, to help break the ice, it is possible to use additional means allowing

  to reduce locally the cohesion and the mechanical resistance

  than the ice layer. These means may be

_- 8 -

  examples adapted for heating the ice in the zone of action of the protuberance or masts. They will, for example, consist of steam ejectors. They can also be physicochemical action, lowering the melting temperature for example, or else purely mechanical action such as vibrators or percussion devices of the kind of jackhammers

operated by compressed air.

- 9 -

Claims (14)

  1. Method for locally breaking a layer of   ice in rigid waters, starting from a primary structure   in the ice or immersed under the ice, characterized in that from this structure the ice layer is subjected to a perpendicular thrust so as to put this layer in flexion and in that it increases the thrust   and bending until cracking and breaking.   2. Method according to claim 1, applicable to a submarine or installation having a submerged portion, characterized in that the thrust is directed upwards on the underside of the ice and is produced by a hydrostatic force. resulting from ballast emptying. 3. Method according to claim 1, characterized in that the thrust is exerted from top to bottom on the   surface of the ice, since a part emerged.   4. Method according to one of claims 1 to 3,   characterized by the implementation of additional thermal, physio-chemical or mechanical means to reduce   the cohesion and the mechanical strength of the ice.   5. Device for the implementation of the   assigned according to one of the preceding claims, characterized   rised in that a submerged craft or a submerged or emerged part of a structure is provided with a protuberance (3) adapted to rest on the ice and transmit to it a   vertical thrust through a support surface (12) anced.   6. Device according to claim 5, characterized   in that the protuberance is in the form of a mast.   7. Device according to one of claims 5 or   6, characterized in that the protuberance is connected to a jack (6, 7), making it possible to move it towards the ice   to put it in touch with it.   8. Device according to one of claims 5 to   7, characterized in that the protuberance or the m & t is - 10 -   consisting of a telescopic system so as to be completely erasable under the surface of the machine or on the contrary, be deployed.   9. Device according to one of claims 7 and   8, characterized in that the jack is of hydraulic type, and is provided with valves (10, 11) for isolating it from the supply and the drain to block it in active position.   10. Device according to claim 9, characterized   by a device for reading the hydraulic pressure acting   in the cylinder and, consequently, of the applied effort on the ice.   11. Device according to one of claims 7 to   , characterized in that the jack is provided with a jacket (13), a casing (14) and bearing rings (15, 16) so as to ensure the protection of the jack and a   greater rigidity of the mast with respect to lateral forces.   12. Device according to claim 5 or 6,   characterized in that the protuberance is connected to a capacitor   mobile city (27) déballastable which by its buoyancy   produces the push on the ice layer.   13. Device according to one of claims 5 &   applied to a submarine, characterized in that the main protuberance (3) arranged on the   the machine, is associated with a second protuberance (5), dis-   placed near the stern to serve as a fulcrum.   14. Device according to claim 13, characterized   in that the additional protuberance is   killed by two diverging masts (Sa, 5b), arranged in a   plane perpendicular to the axis of the submarine.