WO2002018717A1

WO2002018717A1 - Device for making a trench in the bottom of a water area, in particular for laying pipelines or cables

Info

Publication number: WO2002018717A1
Application number: PCT/NL2001/000634
Authority: WO
Inventors: Nico Van Ginkel; Anna Baukje De Jong
Original assignee: Hollandsche Beton Groep N.V.
Priority date: 2000-08-28
Filing date: 2001-08-28
Publication date: 2002-03-07
Also published as: AU2001294372A1; NL1016036C2

Abstract

The invention relates to a device for making a trench in the bed of an area of water, in particular for laying a pipeline or cable (5) in the bed, comprising a vehicle (1) or the like which can move underwater with respect to the said bed and on which there is at least spray arm (12) which is provided with spray nozzles (13) for high-pressure water jets, means being provided for rotating the at least one spray arm out of a rotation point thereof through an angle in the vertical longitudinal plane between an inactive position, in which the spray arm is directed substantially towards the rear, and an active or operating position in which the spray arm is directed substantially downwards. This object is achieved by the fact that for the purpose of internal compensation, one or more spray arms (15) are in the shape of a < which has a first arm (16) and a second arm (17) which are fixedly connected to one another at an angle, the first arm having spray nozzles (18) which face in the opposite direction to the spray nozzles (19) of the second arm.

Description

DEVICE FOR MAKING A TRENCH IN THE BOTTOM OF A WATER AREA, IN PARTICULAR FOR LAYI NG PIPELINES OR CABLES

The invention relates to a device for making a trench in the bed of an area of water, in 5 particular for laying a pipeline or cable in the bed, comprising a vehicle or the like which can move underwater with respect to the said bed and on which there is at least spray arm which is provided with spray nozzles for high-pressure water jets, means being provided for rotating the at least one spray arm out of a rotation point thereof through an angle in the vertical longitudinal plane between an inactive position, in which the spray arm is 10 directed substantially towards the rear, and an active or operating position in which the spray arm is directed substantially downwards.

A device of this type is known from the prior art and is used to cut into and break up earth with the aid of high-pressure water jets which emerge from the spray nozzles of the

15 spray arms. The spray arms, which are provided with one or more rows of spray nozzles, are subject to undesirable reactive forces which have an adverse effect on the operation of the device. Fitting standard compensation means makes these devices relatively cumbersome, and consequently their application areas are limited. The invention aims to overcome these drawbacks. According to the invention, this object

20 is achieved by the fact that for the purpose of internal compensation, one or more spray arms are in the shape of a < which has a first arm and a second arm which are fixedly connected to one another at an angle, the first arm having spray nozzles which face in the opposite direction to the spray nozzles of the second arm.

25 In operation, digging of the trench is commenced by gradually tilting or rotating the at least one spray arm out of the said inactive position, in which the spray arm is oriented in line with the longitudinal direction of the vehicle, into the active, downwardly directed operating position. This rotation of the spray arm through an angle of up to substantially 90 degrees with respect to the horizontal is carried out while the vehicle is moving

30 forwards. As the spray arm is rotating into position, the pump capacity of the jets is gradually increased. It has been found that, with this device according to the invention, efficient and flexible cutting and breaking up of the earth is achieved in types of earth with little or no cohesion, such as sand, but also in types of earth with higher cohesion, such as clay.-

35 In the embodiments described above, as has been stated, water jets are emitted with different exit directions. Consequently, reactive forces will be exerted on the vehicle in directions which are opposite to the said exit directions. To prevent the vehicle from starting to move upwards or sideways in operation, thrusters are generally fitted to the top and/or the sides of the vehicle in the prior art, in order to substantially compensate for these reactive forces. To avoid this use of thrusters, it is possible for at least one spray arm, or part thereof, to be in the shape of a < which has a first arm and a second arm which are fixedly connected at an angle to one another, the first arm having spray nozzles which face in the opposite direction to the spray nozzles of the second arm. As a result of this so-called internal compensation, not only are the forces required for the thrusters reduced or eliminated, but also the forces and powers with which the spray arms are rotated or moved suddenly are also greatly reduced or eliminated altogether.

In one embodiment, the device has two spray arms of this type which are arranged next to one another on the vehicle in order to act on both sides of the pipeline or cable. This is particularly advantageous if the pipeline or cable has a relatively large diameter.

Preferably, the at least one spray arm is provided with at least one or more spray nozzles which are directed substantially downwards at an angle of between 0 and approximately 90 degrees with respect to the longitudinal axis of the spray arm. In an operating position of the spray arm, for example at an angle of 60 degrees with respect to the horizontal, these spray nozzles will emit a water jet which is directed vertically downwards at an angle of 30 degrees with respect to the said longitudinal axis. In practice, it may be advantageous for this water jet to be directed somewhat towards the rear with respect to the vertical, in order to provide an extra forwards impulse for the forwards movement of the vehicle.

To be able to cut into and break up the earth more completely, it is possible for one or more spray arms also to be provided with at least two spray nozzles which are oriented substantially downwards, respectively inwards and outwards, at an angle of between 0 and approximately 90 degrees with respect to the longitudinal axis of the spray arm. In a variant, the exit direction of each of these at least two spray nozzles may vary between the vertical longitudinal plane of the spray arm and the plane which is transverse with respect to this plane and runs through the said longitudinal axis. It is also possible for one or more spray arms also to be provided with one or more spray nozzles which are oriented substantially at right angles to the direction of forwards movement, such as in the direction of an adjacent spray arm. In this case, these transversely oriented spray nozzles maybe arranged offset with respect to one another on two adjacent spray arms. In this context, the term spray nozzle is to be understood as meaning a water exit opening, of which two or more with identical or different exit directions may, if necessary, be accommodated in a combined spray nozzle. In an advantageous embodiment, the abovementioned spray nozzles are distributed in identical groups over the longitudinal direction of the spray arm, so that the water jets from a group of this type emerge in different directions. The earth in the immediate vicinity of this group of spray nozzles is expediently simultaneously exposed to the different water j ets and broken up.

In another advantageous embodiment, there are movement means for causing each spray arm, in its active position, to execute a reciprocating movement in the longitudinal direction, i.e. along its longitudinal axis. It is also possible to provide further movement means for causing each spray arm, in its active position, in which it is inclined downwards, to execute a reciprocating movement in the vertical plane parallel to its longitudinal axis, i.e. for the spray arm to be moved vertically up and down parallel to its longitudinal axis. Furthermore, it is possible, using yet further movement means, to cause each spray arm, in its active position, to execute a reciprocating rotational movement in the circumferential direction, i.e. about its longitudinal axis.

As a result, the earth in the immediate vicinity is exposed to a number of reciprocating water jets and is broken up. These embodiments also make it possible to use fewer water jets and therefore spray nozzles.

The vehicle may comprise a carriage which is guided by a ship, a caterpillar vehicle or a self-propelled vehicle, and may be movable both on top of and above the bed or along the pipeline itself.

The invention will be described in more detail with reference to the appended figures, in which:

Figure 1 shows a view of a device according to the invention which is guided over the sea-bed by a ship while it is laying a pipeline or cable in the bed.

Figure 2 shows a diagrammatic side view of the device according to the invention.

Figures 3a, 3b, 3c and 3d show the possible spraying directions.

Figures 4a, 4b, 4c and 4d show the various reciprocating movements according to the invention. Figures 5a and 5b show embodiments of the spray arm according to the invention, respectively illustrating a < shape with the open side directed towards the front and a < shape with the open side directed towards the rear.

Figure 6 shows a spray arm with two partial spray arms in accordance with Figure 5, each having a row of substantially horizontally oriented spray nozzles.

Figure 7 diagrammatically depicts a pipeline, beneath which there are two h-shaped spray arms, each with two rows of spray nozzles.

Figure 8 diagrammatically depicts a pipeline with two L-shaped spray arms below it.

Figures 9a and 9b show a plan view and a front view of an embodiment of an h-shaped or L-shaped spray arm, it being possible for the short arm to rotate separately.

Figures 9c and 9d show a plan view and a front view of an embodiment of an h-shaped or L-shaped spray arm, this h-shaped or L-shaped spray arm being preceded by a single, vertical spray arm which clears the way.

Figure 10 shows the device shown in Figure 7 or 8, with two spray arms fitted in the longitudinal direction of the vehicle.

Figure 1 diagrammatically depicts a device 1 according to the present invention which is guided by a ship 2 by means of a pull cable or a steering cable 3. The device 1 is pulled over the sea-bed, a trench 4 being made in the sea-bed, which consists, for example, of clay, in order for a pipeline or cable 5 to be laid therein. A line is laid in the trench 4 in order, for example, to protect the line against damage from ships' anchors. Objects which lie on the seabed or just below it may also be damaged by fishing implements involved in fishing using, for example, trawl boards. A further reason for laying lines in the bed is, for example, to prevent them from bending or suffering upheaval buckling. If hot substances are carried in the line, for example hot oil, laying the line in the bed will provide insulation. If the oil in the pipeline were to cool excessively, it would be possible, for example, for wax to form in the oil. For all these reasons, it is advantageous for the line to be laid in the bed.

Figure 2 shows a device according to the invention. This device comprises a vehicle 10 which is supported by wheels 11. A spray arm 12 is mounted rotatably on the vehicle 10. The spray arm can be rotated out of a rear, inactive position, through an angle of 0 to approximately 90 degrees with respect to the horizontal, by means of rotational means 21, into the operating position. During the movement of the vehicle towards the operating location, the spray arm is in the at-rest position. When it has arrived on site, the spray arm is rotated into position, with the pump capacity of the water jets being gradually built up while the vehicle is moving forwards. The spray arm 12 is provided with spray nozzles 13, out of which the water jets can be directed towards the bed. During the cutting into and breaking up of the earth, the water jets are sprayed out of the spray nozzles 13 towards the ground under high pressure.

The spray arm 12 has at least a number of spray nozzles 13 which are at an angle of between 0 and approximately 90 degrees with respect to the longitudinal axis and are directed substantially downwards, as shown in side view in Figures 3a and 3b. Figure 3a shows the spray arm in an operating position at 60 degrees, in which case the spray nozzles are oriented at 30 degrees with respect to the longitudinal axis of the spray arm. In this position, the spray nozzles will emit a jet which is directed vertically downwards. Figure 3b shows a spray arm in an operating position which is at 90 degrees with respect to the horizontal plane, in which case the spray nozzles are directed at 90 degrees with respect to the longitudinal axis of the spray arm. In this position, the spray nozzles will emit a water jet which is directed horizontally forwards. Furthermore, the spray arm 12 may be provided with at least two spray nozzles which are at angle of between 0 and approximately 90 degrees with respect to the longitudinal axis and are directed substantially downwards, respectively inwards and outwards. These at least two spray nozzles may also be directed obliquely forwards at the same abovementioned angle with respect to the longitudinal axis. Figure 3 c shows the possible inward and outward settings for these spray mouthpieces with respect to the longitudinal axis of the spray arm, in plan view. The spray arm may also have one or more spray nozzles 14 which are directed transversely with respect to the direction of forwards movement, for example inwards, such as in the direction of an adjacent spray arm. This possibility is illustrated in Figure 3d. All these nozzles may be distributed in identical groups over the longitudinal axis.

The vehicle 10 is provided with movement means 22 for causing the one or more spray arms 12, in their operating position, to execute a reciprocating movement in the longitudinal direction, i.e. along their longitudinal axis. This reciprocating movement in the longitudinal direction is illustrated in side view in Figure 4a. The extent of this reciprocating movement is preferably equal to approximately the distance between each group of spray nozzles. Figure 4b shows a side view of the movement described above for the situation in which the spray arm has been rotated through 90 degrees into the operating position. Furthermore, there are movement means 23 for causing the one or more spray arms, in their active, downwardly inclined position, to execute a reciprocating movement in the vertical plane parallel to their longitudinal axis, i.e. for the spray arms to be moved vertically up and down parallel to their longitudinal axis. This vertical up-and-down movement is shown in side view in Figure 4c. The vehicle 10 also has movement means 24 for causing the one or more spray arms to execute a reciprocating rotational movement in the circumferential direction, i.e. about their longitudinal axis, as shown in side view in Figure 4d. The means 21, 22, 23 and 24 are diagrammatically illustrated in Figure 2.

Figure 5a shows a <-shaped spray arm 15 according to the present invention. The spray arm 15 comprises a first or main arm 16, which is connected and is at an angle to a second arm 17. The open side of the angle is directed forwards in line with the direction of forwards movement. Each of the arms 16, 17 is provided with spray nozzles. The first arm 16 comprises spray nozzles 18, of which the exit opening is, in the operating position, directed substantially vertically downwards. The second arm 17 comprises spray nozzles 19, of which the exit opening, in the operating position, is directed substantially vertically upwards. It is also possible for the open side of the angle to be directed towards the rear, as shown in Figure 5b; in this case, the downwardly directed spray nozzles 18 and the upwardly directly spray nozzles 19 are respectively arranged on the front side of the second arm 17 and on the front side of the first arm 16. In operation, the reactive forces exerted on the vehicle by the respective spray nozzles 18, 19 will be substantially averaged out. Consequently, there is no resultant of a vertical force which could lift the vehicle upwards.

Figure 6 shows a front view of a spray arm 15 as shown in Figure 5 a, this spray arm having two partial spray arms which run substantially parallel to one another and each have first arms 16 and second arms 17, provided with spray nozzles 18, 19. To further improve the breaking up of the earth, it is possible for each partial spray arm to comprise further spray nozzles 20, the exit opening of which is oriented substantially transversely with respect to the direction of forwards movement. These spray nozzles 20 may be arranged on both spray arms, in such a manner that they are directed towards one another in offset fashion.

Figure 7 shows the situation in which, during the laying of a pipeline 5, the vehicle 10 has two substantially h-shaped spray arms 25, 26 which are positioned opposite one another and each comprise a long or main arm and a short arm connected thereto. The main arm and the short arm connected thereto are substantially designed as <-shaped spray arms 15 with spray nozzles 18, 19. Where necessary, the h-shaped spray arms 25, 26 are provided with spray nozzles 13. At the top of the spray arms 15, the exit openings of the spray nozzles 18 will be directed downwards, and at the bottom of the arms 15 the exit direction of the spray nozzles will be directed substantially vertically upwards. The design may also be the other way round, with the open side of the angle shape directed towards the rear, as has already been explained in connection with Figure 5b.

Figure 8 shows a front view of the device according to the invention, in which the one or more spray arms are substantially L-shaped, with a long or main arm 27, 28 and a short arm 29, 30 which is at right angles thereto. The arms 27, 28 may each be provided with spray nozzles 13. The long arms 27, 28 are either straight, as illustrated in Figure 2, or in the shape of <, as illustrated in Figure 5, in which case the open side of the angle may face forwards or backwards. The short arms 29, 30, which run substantially in the horizontal direction, are either straight or likewise in the shape of a <, with the open side facing either towards the front of the vehicle or towards the rear of the vehicle. Figure 8 shows a design of an L-shaped spray arm with a straight long arm and a horizontally running short arm which is in the shape of a <, with spray nozzles 18, 19.

In order now to substantially average out the reactive forces which are exerted on the vehicle by the spray nozzles of the h-shaped and/or L-shaped spray arms, the long and/or short arms will be of the < shape referred to above and will be provided with spray nozzles with exit directions which are opposite to one another.

In the h-shaped or L-shaped spray arm shown in Figure 7 or 8, the short arm is rigidly attached to a long arm, which can rotate about its longitudinal axis, or the short arm is attached to a non-rotatable long arm and can rotate separately, as shown in plan view and front view for an L-shaped spray arm in Figures 9a and 9b, respectively. In both these variants, the short arm can then be rotated out of an inactive position outside the pipeline or cable into an active operating position beneath the pipeline or cable. In the embodiments which have these h-shaped or L-shaped spray arms, in the forwards direction they are often preceded by a single, vertical spray arm which clears the way. This design is shown in a plan view and a front view for an L-shaped spray arm in Figures 9c and 9d, respectively.

Figure 10 shows a side view of a further embodiment of the device according to the invention. In this case, a plurality of <-shaped spray arms are arranged at a distance from one another in the direction of movement (from the left to the right in the figure) of the vehicle. From the front towards the rear, the spray arms extend increasingly far into the ground. In this way, it is possible, for example, for a cable to be gradually introduced into the ground in accordance with its bending radius. Each of the spray arms 15 comprises some downwardly directed outlet openings 18 and some upwardly directed outlet openings 19.

It will be obvious that further variants are possible within the scope of the invention. For example, the h-shaped spray arms may additionally be provided with an extra, shorter, vertical spray arm. It is also possible for the L-shaped spray arms additionally to be provided with an extra horizontal spray arm.

Claims

1. Device for making a trench in the bed of an area of water, in particular for laying a pipeline or cable in the bed, comprising a vehicle or the like which can move underwater with respect to the said bed and on which there is at least spray arm which is provided with spray nozzles for high-pressure water jets, means being provided for rotating the at least one spray arm out of a rotation point thereof through an angle in the vertical longitudinal plane between an inactive position, in which the spray arm is directed substantially towards the rear, and an active or operating position in which the spray arm is directed substantially downwards, characterized in that for the purpose of internal compensation, one or more spray arms are in the shape of a < which has a first arm and a second arm which are fixedly connected to one another at an angle, the first arm having spray nozzles which face in the opposite direction to the spray nozzles of the second arm.

2. Device according to Claim 1, characterized in that at least two spray arms of this type are provided next to one another in order to act on both sides of the pipeline or cable.

3. Device according to Claim 1, characterized in that each spray arm can be rotated from 0 to substantially 90 degrees out of a position in the horizontal plane.

4. Device according to one of Claims 1 to 3, characterized in that one or more spray arms comprise one or more spray nozzles which are directed substantially downwards at an angle of between 0 and approximately 90 degrees with respect to the longitudinal axis of the spray arm.

5. Device according to one of Claims 1 to 3, characterized in that one or more spray arms comprise at least two spray nozzles which are directed downwards, respectively inwards and outwards, at an angle of between 0 and approximately 90 degrees with respect to the longitudinal axis of the spray arm.

6. Device according to Claim 5, characterized in that the at least two said spray nozzles are each arranged with an exit direction which can vary between the vertical longitudinal plane of the spray arm and the plane which is transverse with respect to this plane and runs through the said longitudinal axis.

7. Device according to one of Claims 1 to 3, characterized in that one or more spray arms comprise one or more spray nozzles which are oriented substantially at right angles to the direction of forwards movement of the vehicle.

8. Device according to Claims 4 to 7, characterized in that the spray nozzles on the spray arm(s) are distributed in identical groups over the longitudinal direction.

9. Device according to one of Claims 1 to 8, characterized in that movement means are provided for causing one or more spray arms to execute a reciprocating movement in the longitudinal direction.

10. Device according to one of Claims 1 to 8, characterized in that further movement means are provided for causing one or more spray arms to execute a reciprocating movement in the vertical plane parallel to the longitudinal axis.

11. Device according to one of Claims 1 to 8, characterized in that yet further movement means are provided for causing one or more spray arms to execute a reciprocating rotational movement in the circumferential direction.

12. Device according to Claim 9, 10 or 11, characterized in that the reciprocating movement of the said movement means is substantially equal to the distance between each group of spray nozzles.

13. Device according to one of the preceding claims, characterized in that at least one spray arm is substantially h-shaped, with a long arm and a short arm running parallel thereto, it being possible to rotate the short arm out of an inactive position, which lies outside the pipeline or cable, into an active operating position beneath the pipeline or cable.

14. Device according to one of Claims 1 to 12, characterized in that at least one spray arm is substantially L-shaped, with a long arm and a short arm which is at right angles thereto, it being possible to rotate the short arm out of an inactive position, which lies outside the pipeline or cable, into an active position beneath the pipeline or cable.