METHOD AND APPARATUS FOR COVERING AN OBJECT ON A BOTTOM SURFACE

Abstract

 A method to cover a wreck (1) on a bottom surface (3) of a bottom of a water area by using bottom sediment from the bottom, the method comprises to: mix the bottom sediment with water from the water area to achieve a cavity (5) in the bottom. The cavity (5) permits that a landslide of the bottom sediment under and/or around the wreck (1) is achieved, which causes the bottom sediment under and/or around the wreck (1) to move down into the cavity (5), wherein a distance (d) between at least one point (p) on the surface of the wreck (1) and the bottom surface (3) is changed when the bottom sediment under and/or around the wreck has moved down into the cavity (5). While and after the bottom sediment under and/or around the wreck has moved down into the cavity (5), the wreck (1) is covered with at least the bottom sediment that has been mixed. An arrangement (9) adapted for mixing a bottom sediment of a bottom of a water area with water from the water area to achieve a cavity (5) in the bottom is also described.

Description

TECHNICAL FIELD

[0001] The invention concerns under water applications and especially to handling of objects on the bottom of a water region.

BACKGROUND

[0002] In the sea around the world and even in lakes there are very many wrecks such as shipwrecks mainly from World War II. These wrecks often contain substances harmful to the environment, which substances can be released and eventually can be spread into the surrounding water during ongoing corrosion processes that break down the wreck.

[0003] The document EP1675768B1 describes an example of a method for handling of substances harmful to the environment in a wreck. More particularly the EP1675768B1describes a method and a system for collecting oil from a wreck by placing a covering device at the wreck. The collected oil is pumped up for further transportation.

[0004] Despite the known solutions within the field, there is a need of an efficient method and an efficient apparatus adapted for handling of for example wrecks on a bottom surface in order to at least reduce the risks for environmental impacts that may be caused by the breakdown processes of the wrecks during the time the wrecks are on the bottom surface.

SUMMARY

[0005] One object of the invention is to provide, from an environmental perspective an efficient method for handling of an object on a bottom surface of bottom in a water area and to achieve an efficient method to cover the object by using the bottom sediment from a cavity in the bottom.

[0006] The object is achieved by a method to cover a wreck on a bottom surface of a bottom of a water area by using bottom sediment from the bottom. The method comprises mixing of the bottom sediment with water from the water area to achieve a cavity in the bottom. Thus, the bottom sediment is suspended with water from the water area. Thereby, the bottom sediment is mixed with water from the water area during the time the cavity is created. With other words suspension or mixture of the bottom sediment and water is accomplished while the cavity is created. With a cavity is therefore meant a zone in the bottom with partially looser bottom sediment comparing to the bottom sediment that has not been mixed with water. The looser bottom sediment is obtained by mixing the bottom sediment with water at use of the method.

[0007] The cavity is created to permit that a landslide of the bottom sediment under and/or around the wreck is achieved, which landslide causes the bottom sediment under and/or around the wreck to move down into the cavity. Thus, the cavity is created on such a distance from the wreck and with such a depth that the bottom sediment under and/or around the wreck collapses and moves down into the cavity. With other word, conditions to achieve a landslide are established by digging or flushing of the cavity.

[0008] Further, when the bottom sediment has moved down into the cavity a distance between at least one point on the surface of the object and the bottom surface is changed. Thereby, the object is sinking in relation to the ambient bottom surface when a landslide has been achieved, i.e. I relation to the initial bottom surface before the landslide and also in relation to the ambient bottom surface that not been effected by the landslide.

[0009] According to the method, the object is covered with at least the suspended bottom sediment while and after that the bottom sediment under and/or around the object has been moved down into the cavity. The suspended bottom sediment, but also the bottom sediment that is drawn with the water streams or that in a different way has been mixed with water, is covering the object simultaneously and after that the bottom sediment under and/or around the object has been moved down into the cavity. Thereby, a landslide is achieved which causes the object to sink. Further, the object is covered by at least the suspended bottom sediment. With this, the object is encapsulated in the bottom sediment. In other words, the object is buried into the bottom sediment.

[0010] Because the bottom sediment has been buried in the bottom sediment, the degradation processes, such as corrosion of the abject may be stopped or at least reduced, which reduces the risks for environmental impacts that may be caused by degradation of the wreck. Further, due to a layer of bottom sediment that has covered the object, also the risks for undesirable substances from the object that may come out from the object and that may be spread in the water is reduced.

[0011] Thus, an efficient method is achieved to cover an object on a bottom surface of a bottom of a water area by using the bottom sediment from the bottom. Thereby, the object mentioned above is achieved.

[0012] The method may comprise to achieve a break indication in the bottom sediment adjacent to the object and on the substantially opposite side of the wreck in relation to the cavity. With the break indication is meant an elongate pit, hole or channel that is digged or flushed in the bottom sediment on the substantially opposite side of the object in relation to the cavity to achieve a landslide as described above. With a break indication a displacement of the bottom sediment into the cavity is facilitated when the bottom sediment releases at the break indication. Furthermore, a controlled landslide may be achieved with a break indication.

[0013] The break indication may have a form of an arc i.e. that may extend along a crooked line. The break indication may for example have a form of a half-circle. Thereby the object may at least partially be enclosed in order to facilitate said landslide and to achieve a better control of the movement of the bottom sediment into the cavity.

[0014] The method may further comprise to decide the nature of the bottom sediment and the depth conditions. Thus, for example, the sort of the soil mass forming the bottom sediment can be determined. Likewise, the depth of the bottom sediment can be determined before said cavity is achieved. In this way, a better control over the step of achieving the cavity may be obtained.

[0015] As an alternative the cavity may be achieved by a beam of pressurized water is directed towards the bottom. Thereby the bottom sediment may be mixed with water in an efficient way while the cavity is accomplished.

[0016] The object may be a wreck such as a boat wreck or aircraft wreck.

[0017] The method may comprise monitoring of the movement of the bottom sediment and the wreck down into the cavity by using a monitoring device. With monitoring of the movement of the bottom sediment down into the cavity some risks connected to the implementation of the method may at least reduced.

[0018] An another object of the present invention is to provide, from an environmental perspective an efficient arrangement for handling of an object on a bottom surface of bottom of a water area and to achieve an efficient arrangement to cover the object by using the bottom sediment from a cavity in the bottom.

[0019] The object is achieved according to another aspect of present invention by an arrangement adapted for mixing of a bottom sediment of a bottom of a water area with water from the water area to achieve a cavity in the bottom, wherein the arrangement comprises: at least one nozzle connected to a pump arranged to pump water through the at least one nozzle to achieve a beam of pressurised water. Further the arrangement comprises a control unit, a platform with hydraulic winches, arranged to position the at least one nozzle towards the bottom and a balance pontoon.

[0020] Thus, the nozzles may be positioned in a correct way towards the bottom by the platform and further a cavity may be created in the bottom by using the beam.

[0021] Thus, the above mentioned object is achieved.

[0022] The platform may comprise a monitoring device. Thereby, an improved arrangement adapted to achieve a cavity in a bottom if a water area is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The various aspects of the subject matter, including their particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which:

Fig. 1 illustrates an object on a bottom,

Fig. 2 illustrates the object in Fig. 1 and a cavity on the bottom,

Fig. 3 illustrates a landslide caused by the cavity in Fig. 2,

Fig. 4 illustrates the object in Fig. 1-3 that has been covered by the bottom sediment and

Fig. 5 illustrates an apparatus to achieve the cavity in Fig. 2.

DETAILED DESCRIPTION

[0024] The embodiments herein will now be described in more detail with reference to the accompanying drawings, in which example embodiments are shown. Disclosed features of example embodiments may be combined. Like numbers refer to like elements throughout.

[0025] Fig. 1 illustrates an object 1 on the bottom 2 of a water area, such as for example of a sea. According to Fig. 1, an arrangement 9 has been positioned on the bottom surface 3 on the bottom 2. The arrangement 9 will be described in details in conjunction with Fig. 5. The arrangement 9 may be connected to a boat 4. The object 1 may be a wreck. Because the wreck, that for example may be a ship wreck, is located on the sea bottom, the wreck has, to some extent, been stabilized there, i.e. the wreck has been stabilized in the bottom sediment. With a constructed and controlled landslide of the surface that is desired, you can achieve that the ship wreck may slide on its bottom bed without any bigger strains down into a predetermined flushed cavity, and to be covered of the loose water saturated sludge from the cavity. The sludge may also be called dredged material. During the time, for instance, the suspended bottom sediment will stabilize, as all other dredged material, and will isolate the wreck from for example oxygen. Thereby, the corrosion processes may be at least reduced.

[0026] Fig. 2 illustrates that a cavity 5 has been achieved by using the arrangement 9 near to the object 1. As illustrated in Fig. 2 also a break indication 7 has been digged or has been flushed on the other side of the object 1 in relation to the cavity 5. The break indication 7 that also may be called a groove can be achieved using the arrangement 9. As illustrated in Fig. 2, a suspension is achieved, i.e. a mixture of the bottom sediment and water during the time the cavity is created by using the arrangement 9.

[0027] The distance g between the cavity 5 and the wreck 1 may for example be about 15-30 meters and can be measured from the center C of the cavity to an edge of the wreck 1. The depth of the cavity can for example be twice the height of the wreck and, for example 20-30 meters. The break indication 7 may be created at a distance b of, for example 10-20 meters from the wreck 1, depending of the size of the wreck and depending on the nature of the bottom sediment. The depth of the break indication may for example be the height of the wreck.

[0028] Knowing the nature of the bottom sediment means that you know something about the characteristics of the seabed i.e. "the ground mass" in the current area of landslide. The sediment may consist of sand, clay, mud or the like. In order to plan how much and how deeply you need to flush to create the cavity, it may be an advantage to know the nature of the bottom sediment.

[0029] The break indication may have a form of a groove that may be flushed around the wreck in the form of an up and down turned U, with start and finish where the sediment grave is planned, i.e. in the opening of the U. The advantage of this form is that friction against the slopes of the landslide is eliminated and that the landslide will be cut out as a cake. Depth of this groove i.e. on the break indication 7, behind the wreck, in the bow itself can be about 10 meters. And both straight stretches of the U may be flushed of a falling bottom on the grooves down to the depth of the planed cavity which is about 40 meters. The side slope may be about 30 - 40 degrees. The size of the flushed sediment grave may be 1/2 times the length of the ship wreck. An estimated size of an example wreck (Liberty ship) is L (length) 130 m, B (wide) 17 m and Displacement 14,250 tons.

[0030] Figure 3 shows that a landslide has been achieved by means of the cavity in Fig. 2 and due to forces on the sediment mass below and around the object caused by, inter alia, the weight of the object but also by the weight of the sediment mass.

[0031] As shown in Fig. 3, the bottom sediment below and/or around the object 1 has been moved down into the cavity 5. Thus, an opening in the bottom defined by the outer edges of the cavity 5 and of the break indication 7 has been achieved. The object has sunk down and a distance d between at least one point p on the surface of the object and the bottom surface 3 has increased. When the object starts to slide down, the nozzles of the device 9 are lifted.

[0032] Fig. 4 illustrates that the object 1 in Fig. 1-3 has been covered by the bottom sediment after a time when conditions around the object have been stabilized. The object has been covered by the bottom sediment from the cavity 5. Over time, the object 1 may also be covered by bottom sediment that flows in with ocean currents.

[0033] The layer of the bottom sediment that covers the object may for example be 1 m or more when an encapsulation of the object is done in order to at least reduce the corrosion processes of the object.

[0034] Figure 5 illustrates a device 9 adapted to achieve the cavity 5 as illustrated in Fig. 2. The device 9 comprises: at least one nozzle 11 connected to a pump 13 arranged to pump water through the at least one nozzle 11 to create a beam of pressurized water and a platform 15. A monitoring device 17 such as echo sounder or camera or sonar may be placed at the platform 15.

[0035] The device 9 may comprise a plurality of nozzles 11. The nozzles 11 may be self-digging nozzles with outlet channels angled upwardly.

[0036] In order to orient a wreck and to check the wreck position, transponders can be used. With these you can see how deep the wreck is buried and precise positioning for future interests.

[0037] The dimensions of the device 9 may be about 60 x 25 meters and may comprise two or more pontoons for overflow mode which are filled with air during transport (towing). Further, the device 9 may comprise a balance pontoon. The pontoons may be designed to cope with all existing work depths. The electronics and controllers may also be included in the device. Thrusters, as for example four electrically powered for actuating the device 9, up and down and laterally, may be included in device 9 too. Two of these may also be used in overwater mode for actuating of the device 9. A certain number of pumps connected to encapsulated electric motors and encapsulated hydraulic winches with swivel-operated coil hoses may also be used. Flushing nozzles may be designed as self-draining down at the bottom through rear directed jets as well as a control valve for flushing of the side for the best mixture, water, clay may be used. Four beams for each maneuver and a beam ahead can be arranged as an example. The control valve can be a hydraulic cylinder that is pressurized with high pressure water from one or several hoses.

[0038] On the boat, electric generators and a cable drum may be provided and connected to the device 9. The device 9 may comprise a guillotine for cutting the hose if the device gets stuck into the sediment.

Claims

1. A method to cover a wreck (1) on a bottom surface (3) of a bottom of a water area by using bottom sediment from side bottom, the method comprises:

mixing the bottom sediment with water from the water area to achieve a cavity (5) in said bottom,

wherein the cavity (5) permits that a landslide of the bottom sediment under and/or around the wreck (1) is achieved, which causes the bottom sediment under and/or around the wreck (1) to move down into the cavity (5),

wherein a distance (d) between at least one point (p) on the surface of the wreck (1) and said bottom surface (3) is changed when the bottom sediment under and/or around the wreck has moved down into the cavity (5),

wherein while and after the bottom sediment under and/or around the wreck has moved down into the cavity (5), the wreck (1) is covered with at least the bottom sediment that has been mixed.

2. The method according to claim 1, wherein the method comprises to achieve a break indication (7) in the bottom sediment adjacent to the wreck and on the substantially opposite side of the wreck in relation to the cavity (5).

3. The method according to claim 2, wherein said break indication (7) has a form of an arc.

4. The method according to any one of the preceding claims comprising to decide the nature of the bottom sediment and the depth conditions.

5. The method according to anyone of the preceding claims, wherein the cavity (5) is achieved by a beam of pressurized water that is directed towards said bottom.

6. The method according to anyone of the preceding claims, comprising monitoring the movement of the bottom sediment and the wreck down into the cavity (5) by using a monitoring device.

7. An arrangement (9) adapted for mixing of a bottom sediment of a bottom of a water area with water from the water area to achieve a cavity (5) in said bottom, wherein the arrangement comprises:

- at least one nozzle (11) connected to

- a pump (13) arranged to pump water through the at least one nozzle (11) to achieve a beam of pressurised water,

- a control unit,

- a platform (15) with hydraulic winches, arranged to position said at least one nozzle (11) towards said bottom and

- a balance pontoon.

8. The arrangement (9) according to claim 8, wherein said platform (15) comprises a monitoring device (17).

Drawing