Positioning Arrangement and Method for Positioning at Least One Object on a Water Bottom

The present application relates to an arrangement for positioning one or more objects under the water level on a sea, lake or river bottom, and to a method for such positioning.

DE 10 2021 128 776 A1 discloses a depth vibrator assembly that includes several top fed depth vibrators and that is suspended by a crane via a spreader bar on land-based applications.

However, for many construction projects it would be desirable to use deep vibrators also under water in the soil covered by the water to produce stone columns or the like in the soil. This, however, is challenging at least for the following reasons:

A first aspect of the system described herein relates to a positioning arrangement for positioning an object under water on a water bottom. The positioning arrangement includes a barge configured to float on the water; a carrier rig positioned on the barge; a rope arrangement that suspends the object from a mast of the carrier rig; and a positioning aid. The positioning aid includes at least one of: (a) a constraining arrangement arranged between the mast and the object and configured to restrict a lateral movement of the rope arrangement: and (b) a turntable arrangement configured to adjust a rotational position of the object about a vertical swiveling axis (a).

A further aspect relates to positioning an object under water on a water bottom by providing a positioning arrangement according to the first aspect; determining an actual position of the barge; determining an actual position of the object; controlling at least one of the constraining arrangement and the turntable arrangement to approach the object to a desired position above the water bottom based on at least one of the determined actual position of the barge and the determined actual position of the object.

Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

The system described herein generally relates to improving the underwater positioning of single or multiple objects (e.g. one or more depth vibrators) at a desired position (e.g. a starting point for the vibratory operation of one or more depth vibrators) on a sea, lake or river bottom under water. In the present application, the term “water bottom” is intended to include a sea, lake or river bottom, or a bottom of any other water or liquid reservoir.

One aspect of the present system described herein is the use of a positioning aid that improves the positioning accuracy of an object immediately above a desired position on a water bottom. The positioning aid may include at least one of a constraining arrangement and a turntable arrangement, i. e. a constraining arrangement and/or a turntable arrangement.

The constraining arrangement constrains a lateral movement of a rope arrangement, e.g. one or more ropes, used to suspend an object from a mast of a carrier rig. This is explained in more detail with reference toand IB.schematically illustrates a positioning arrangementthat includes a carrier rigpositioned on a barge. In the drawings of the present disclosure, the carrier rigis illustrated as crawler crane. Instead of a carrier rigthat can drive on the barge, however, any other suitable carrier rig/suspension, such as for example a rigid tower mast (which is, for example, fixed to the barge, without an undercarriage with which the carrier rigcan drive on the barge), could be used as well. The bargeis floating on waterof the sea, a lake or a river. The bottomof the sea, lake or river (in the following also referred to as “water bottom”) is formed by top side of soiland covered by the water. Using a rope arrangement, an object, e.g. a single depth vibrator assemblyor a group of depth vibrator assemblies, is suspended from a mastof the carrier rig. As illustrated, the objectmay be fully immersed in the water. The rope arrangementincludes at least one rope, e.g. one, two or more than two wire ropes. Starting from a winch, from which each ropeis unwound and/or onto which it is wound, the ropeis guided over a sheavewhich is mounted to the mast. Hanging on the rope(s)(e. g. at end(s)of the rope(s)), the objectis positioned immediately above a desired position P on the water bottom.

The positioning aidis arranged between the sheaveand the objectand includes a constraining arrangementwhich constrains a lateral movement of the rope arrangementwhich in the present example is a single rope. In the sense of the present disclosure, “lateral” refers to a direction perpendicular to the vertical direction, where the vertical direction is the direction of gravity. The constraining arrangementmay constrain the lateral movement of the rope arrangementin one, more than one or each lateral direction. According to one example, the lateral movement of the ropeof the rope arrangementmay be constrained by an open or closed ring which is part of the constriction arrangementand through which the ropeis guided. As illustrated in, the constriction arrangementmay be directly or indirectly mounted to the barge.

When the water is calm (i.e. no waves, no water current), the objectis at a lateral distance do from a reference axis r about which the bargerolls.

In contrast,illustrates the positioning arrangementofwith the bargetilted by wave action. For the sake of clarity, however, the surfaceof the wateris illustrated by a straight line, i.e. the waves on the surfaceof the waterare omitted. Compared to the situation with calm water, the lateral distance between the reference axis r of the bargeand the objectchanges due to the tilting of the bargeby dl.

also shows with a dashed lines that the lateral distance between the reference axis r and the objectwould change by dif the ropewere not restricted by the constriction arrangement. As can be seen, dl is smaller than d, i.e. the constriction arrangementincreases the positioning accuracy of the object. The reason, why dl is smaller than d, is that the constriction arrangementis arranged closer to the objectthan the sheave. In order to enhance this effect, the constriction arrangementcould alternatively also be arranged adjacent to a side wall of the bargein a lateral direction as exemplarily illustrated by dotted lines in. The closer the constriction arrangementis positioned to the axis r of barge rotation, the smaller the deviation dl becomes. The principle described above with reference toand IB is also used in the following examples.

is a top view of a positioning arrangementthat includes the carrier rigarranged on the barge, andis a cross-sectional view of the positioning arrangementin a cross-sectional plane A-A. The rope arrangementthat is operated from two synchronized winchesmounted on the carrier rigcarries the objectwhich in the present example are several bottom fed depth vibrators assemblies. Each of the bottom fed depth vibrators assembliesincludes a hopper, a gravel tank, a silo tubeand a depth vibrator. The depth vibrator assembliesare each connected, via ropes, but possibly also fixed or with a flexible joint connection, to a same spreader barthat itself is carried by two of the ropesof the rope arrangement. The spreader barand the ropesare parts of the object.

While the bargeis in approximate alignment with future stone columnlocations on the water bottom, such alignment can never be precise enough to fully rely on such alignment for navigating the depth vibrator assemblies with sufficient accuracy and precision to such point locations. Inthe positioning of the depth vibrator assembliesis assisted by a positioning aidthat includes a localizer platformand a movable constraining arrangementmounted to the localizer platform.

The localizer platformmay move along the edge of the barge, i.e. substantially in a lateral direction. As schematically illustrated In, the localizer platformmay be rolling on wheels. Instead of or in addition to the wheels, any other mechanism for moving the localizer platformrelative to the bargemay also be used.

The movable constraining arrangementcan connect to the rope arrangement, i.e. to the ropes, in a way that the ropesare not hindered in vertical movement of the ropesbut constrained by the constraining arrangementin all lateral directions. As illustrated in, the constraining arrangementmay include two constraining elements, each constraining a movement of one of the ropesin all lateral directions. Each of the constraining elementsis mounted to a hydraulic cylinderand can be moved in a lateral direction relative to the localizer platformusing the respective hydraulic cylinder. The hydraulic cylindersare in turn mounted on the localizer platform.

According to the embodiment of, each of the constraining elementsmay be formed as a clamp that can open and close around one of the ropes. With the crane masthigh up above the constraining elements, the constraining elementscan be moved relative to the bargeby moving the localizer platformrelative to the barge(e.g., along a sidewall of the barge) and by moving the constraining elementsrelative to the localizer platform(e.g., by expanding and/or contracting the hydraulic cylinders).

Instead of or in addition to the hydraulic cylinders, any other suitable actuator (e.g. pneumatic, electric or electromagnetic) may be used as well.

To bring the objectto a desired position P (seeand IB) immediately above the water bottom, the bargeis positioned roughly above the desired position P. Then, a fine adjustment is made so that the relative position of the constraining arrangementrelative to the bargeis adjusted by suitably adjusting the relative position between the localizer arrangementand the barge, and by suitably adjusting the stroke of the hydraulic cylinderrelative to the localizer arrangementin such a way that the submerged objectis located sufficiently precisely above the desired position P.

The above-described positioning of the objectto the desired position P immediately above the water bottommay use underwater surveying of the objectin order to obtain the actual (lateral) position of object.

When the actual lateral position of the objectis known, the desired lateral position P of the objectcan be approached using the control electronicswhich receives information on the actual (lateral) position and/or rotational position of the objectand which suitably adjusts the relative (e.g. lateral) position between the localizer platformand the bargeas well as the relative (e.g. lateral) position between the constraining arrangement(i.e. the constraining elements) and the localizer platformso that the position of the constraining elementsaffects the positions of the ropesand thus also the position of the object. Optionally, the control electronicsmay adjust a rotational or pivotal position of the objectby appropriately controlling a turntable arrangement(cf.and the related description) and/or by appropriately controlling a rotatable crane mast head,,,(cf.and the related description) in order to approach the desired lateral position P of the object. Optionally, a GPS position (lateral position and/or rotational position) of the barge(e.g. with the aid of differential GPS) and an inclination of the barge(e.g., provided by inclination sensors) can also be taken into account in connection with positional control. The control electronics, e.g., a control computer, may be mounted at any suitable location, for example on the carrier rigor the barge.

Summarized, the control electronicsmay permanently regulate the relative position between the bargeand the constraining arrangementand/or the rotational position of the objectin order to approach the desired position P of the objecton the water bottom. The control electronicsmay control the position of the constraining arrangement(if provided), the position(s) of the end(s)of the one, two or more than two of the ropes(i.e., the endshanging down from the mast) via the rotational position(s) of the winch(es)and the rotational position of the turntable arrangement(if provided) via the turntable driveand alternatively also control an angle cp of the hinge(cf.and the related description).

There are various ways to achieve underwater surveying of the object(e.g. multiple depth vibrator assemblies). One way is schematically illustrated in, where an echo sounding deviceis attached to an extension rodthat is itself connected to the barge. By the echo sounding signalfrom the echo sounding device, the distance between the bargeand the objectcan be determined. The bargeitself may be permanently surveyed by differential GPS. Optionally, inclination sensors may acquire the inclination of the bargein two lateral (e.g. perpendicular) directions which leads to an at any time known position of the echo sounding device. Several such echo sounding devices(e.g. an array) may be used to properly triangulate the position and optionally also the orientation of the objectunder water. For the sake of clarity, the additional echo sounding devices are omitted in.

schematically illustrate an example of the positioning arrangementthat employs an alternative embodiment of the constraining arrangement.is a top view andis a cross-sectional side view in a cross-sectional plane A-A. The construction and operation principle of the localizer platformmay be the same as described with reference to. As also described with reference to, the movable constraining arrangementis mounted to the localizer platform, and the movable constraining arrangementcan also connect to the rope arrangement, i.e., to the ropes, in a way that the ropesare not hindered in vertical movement of the ropesbut constrained by the constraining arrangementin all lateral directions. In the embodiment of, the constraining arrangementincludes pairs of bifurcated (e.g. v-shaped) constraining elements.

Each of the bifurcated constraining elementsis operated by a respective hydraulic cylinderto which the respective constraining elementis mounted. Thereby, the two free ends of the bifurcated constraining elementpoint away from the hydraulic cylinder. Arranging the two bifurcated constraining elementsof a pair and the respective hydraulic cylinderssuch that each of the constraining elementscan be moved towards and/or away from the other one of the constraining elementsallows the pair of constraining elementsto assume an unconstrained configuration and a constrained configuration.

In the constrained configuration, the constraining elementsof the pair can embrace one of the ropessuch that the pair constrains the lateral movement of the ropein each lateral direction. For example, the respective ropemay be fully surrounded by the bifurcated constraining elements. In, the left two constraining elementsform a pair that is in the constrained configuration.

In the unconstrained configuration, the constraining elementsof the pair are spaced far enough apart that the constraining elementsdo not constrain the lateral movement of a rope. In, the right two constraining elementsform a pair that is in the unconstrained configuration.

This embodiment of the constraining arrangementhas the advantage that no clamping mechanism such as the clamping elementsdescribed with reference tois required. The use of two independent but in synchronized winches(cf.) allows for an adjustment of the spreader barto not have any deviation from the horizontal. This is important when a groupwith multiple depth vibrator assembliesis subjected to water currents and also in connection with the use of the above-described localizer platform. Having the spreader barhorizontal helps in achieving a more vertical penetration of the group of multiple depth vibrator assembliesinto the soil.shows the group of multiple depth vibrator assembliesduring vibratory action in which the soil(cf., IB,A,B,A,B) is compacted by the depth vibratorsof the multiple depth vibrator assemblies.show the multiple depth vibrator assemblieswhile being filled via the hopperswith a filling material like stones, gravel, sand, bentonite, cement, concrete, etc. from a supply silothat is arranged on the barge.is a cross-sectional side view in a cross-sectional plane B-B in. During such filling, the whole localizer platformcan slide out of the way of the spreader barand the multiple depth vibrator assembliessuspended below the spreader bar(e.g. to the very right side of the bargeas illustrated in).

In the filling position, the arrangement of the spreader baris no longer perpendicular to the crane mast. This can be achieved with one of the following three ways:

Instead of filling the hoppersof the depth vibrator assembliesindividually from the material silo, the filling material can also be transported with air or water as transport media through hoses to each such hopperindividually. In this case, the process of filling may also take place with the depth vibrator assembliescompletely immersed in the water.

In yet another variant, the multiple hopperscan be filled from an additional so-called distribution tank, which is located between the spreader beamand the group of depth vibrator assemblies. Such distribution tank can be filled either from the material siloor via hoses, which are not shown in the drawings. As is clear from the description ofand IB, the lateral movement of the multiple depth vibrator assembliesrelative to desired positions P of the multiple depth vibrator assemblieson the water bottomis minimum, if the movement of the ropesin all lateral directions is restricted at a level that is very close to the center of rotation of the barge, even if the rolling motion of the bargeis very large. Therefore, such a low position of the constraining arrangement(e.g.

the constraining elementsdescribed with reference toor the constraining elementsdescribed with reference to) and also of the localizer platformis advantageous. For instance, the constraining arrangementand the optional localizer platform(if provided) may be arranged adjacent to a side wallof the bargein a lateral direction. This is schematically illustrated in.

Compared to,show a conventional positioning arrangementwhich differs from the positioning arrangementaccording to the invention shown inin that there is no constraining arrangement(and also no optional localizer platform).shows the conventional arrangement in calm sea conditions (no waves, no water current) with the depth vibrator assembliesimmediately above the respective desired position P on the water bottom, andshows the arrangement according to, but in swell conditions, whereby the bargeis tilted and the depth vibrator assembliesare laterally displaced with respect to the respective desired position P. In comparison, the bargeinhas the same tilt as in, but the lateral offset of the depth vibrator assembliesfrom the respective desired position P is much smaller due to the constraining arrangement(and the optional localizer platform). Furthermore, there is an added benefit that forces on the crane mast stay closer to the axis of the mastin the arrangementof the present invention than in the conventional arrangement. Thereby, the sideways forces onto the mastare reduced, which in turn increases the overall stability of the crane and makes it workable over a larger range of wave heights.

However, even though inthe position of the constraining arrangement(and the optional localizer platform) laterally adjacent to a side wallof the bargeis described as optimal, also higher positions have a large advantage compared to the conventional positioning arrangementofwithout a constraining arrangement. It is expected that with a constriction arrangementand—optionally—a localizer platform, the work offshore can be extended to higher wave heights than without such devices and that at the same wave height the accuracy and precision of locating any object(a depth vibrator assemblyor a group of the depth vibrator assemblies) at a desired position P on the water bottomis greatly improved.

As further illustrated in, the positioning aidmay include a turntable arrangement.is an enlarged view of the turntable arrangementofand the object(in the present example a group of the depth vibrator assembliescommonly mounted to a spreader bar) attached to the turntable arrangement.

The turntable arrangementmay be provided in addition to or—as illustrated in—instead of the constriction arrangementas explained with reference to the above Figures. As illustrated in, the turntable arrangementmay include a turntable, a motor driveand a holding bar. The holding baris mounted to the ropes. The motor driveis configured to rotate the turntablerelative to the holding barabout a vertical swiveling axis a. The object(here the spreader barand the group of depth vibrator assembliesmounted thereto) is mounted to the turntableso that a rotation of the turntablecaused by the motor drivewill also rotate the objectrelative to the holding barso that a desired orientation (rotary position) of the objectcan be adjusted by appropriately driving the motor drive.

For example, the turntable arrangementmay be used to rotate the spreader barso that the spreader barstays parallel to the edge of the bargewhen the spreader barand the group of depth vibrator assembliesis moved to the filling silo().

The turntable arrangementcould also be used together with a localizer platformand the constriction arrangementif the group of depth vibrator assembliesmust be turned left and right, e.g. by 60 degrees, to work in a triangular and not square stone column grid pattern. In this case, most of the positioning would be achieved by the turntable, and the constraining arrangementmounted to the localizer platformwould only constrain the ropesas much as possible in each lateral direction without bothering about the 60 degree rotation of the depth vibrator assembliesaway from that lineup, as this later part would be taken over by the turntable arrangement.show the top of a mastthat is prepared to operate two independent ropesthat can be synchronized during normal operation. In this sense, “synchronized” means that the two ropesare wound and unwound in the same direction and at the same speed by the two winches(). However, there can also adjustments be made to such synchronization to assure that a spreader baras explained with reference to the previous Figures remains horizontal.

Attached to the upper end of the mastthere is a swivel segmentthat can be swiveled about a swiveling axis b using a hingethat pivotably couples the swivel segmentto the mast. In, the swivel segmentis in the center position (neutral position), while inthe swivel segmentis pivoted to the left by an angle cp relative to a longitudinal axisof the mast. Similarly, the segmentcan also be pivoted to the right relative to the longitudinal axisof the mast. In the center position (neutral position;), the angle cp is 0°.

The hingeincludes a control motor configured to adjust a desired pivotal position of the swivel segmentrelative to the mast. Attached to the swivel segmentthere is a hammerheadwhich swivels about the hingetogether with the swivel segment. For each of the ropes, the hammerheadcontains a deflection sheavewhich deflects the respective ropecoming from one of the winchesdownwards. The deflection sheavesalso swivel about the hingetogether with the swivel segment(and the hammerhead).

For the two ropesto not fall off the top sheaves, there are guide wheels,that guide the ropesaround a left or right curve as the hammerheadis pivoted accordingly. The guide wheelsare mounted to the mastand the guide wheelsare mounted to the swivel segmentand swivel together with the swivel segmentabout the hinge. The assembly that includes the swivel element, the hammerhead, the deflection sheavesand the guide wheelscan also be considered as pivotable or rotatable mast head.

Such a rotatable crane mast head,,,may be used instead of a turntable arrangementas described with reference to, or may be omitted. Alternatively, such rotatable crane masthead,,,can complement the turntable arrangementas a fallback device for orienting the depth vibrator assembliesalongside the edge of the bargewhen the depth vibrator assembliesare moved into a position close to the filling silo. However, it is also possible to omit both the rotatable crane mast head,,,and the turntable arrangement.

It is to be noted that the features described in connection with the above figures can be combined unless they are mutually exclusive.

In the following, some example embodiments of the system described herein are summarized. Other embodiments can also be understood from the entirety of the specification and the claims filed herein.

Example 1. Arrangement of for example multiple depth vibrator assemblies or other needle shaped multiple probes or generally any objects that need to be located with some accuracy on the seabed while being suspended by at least one wire rope from a carrier rig standing on a floating barge, such that the wire rope is guided through some fixed point via a localizer platform () and constraining devices (,,), thereby improving greatly the positional accuracy of the objects in case of rolling movement or any other movement of the barge ().

Example 2. Arrangement according to example 1 for example multiple depth vibrator assemblies or other needle shaped multiple probes or generally any objects that need to be located with some accuracy on the seabed while being suspended by at least two independent but synchronizable wire ropes from a carrier rig standing on a floating barge, such that both wire ropes are guided through some fixed points via a localizer platform () and constraining devices (,,), thereby improving greatly the positional accuracy of the objects in case of rolling movement or any other movement of the barge (). Such positioning is improved further when the level of the constraining devices (for example,,) is located close to the level of rotation of the barge ().

Example 3. Arrangement according to example 2, whereby the position accuracy of the spreader bar () is not only improved around the vertical (z) axis by the constraining devices (,,) but also in a horizontal orientation of the spreader bar () by using two independently controllable winches () to lower one of the two ropes or raise the other, until the spreader bar () is horizontal.

Example 4. Arrangement according to example 1 and 2 with added ability to rotate the spreader bar () around the z-axis (vertical direction) using a turntable arrangement according to.

Example 5. Arrangement according to example 1, 2, and 3, whereby the turntable according to example 3 is replaced or complemented by a rotatable mast head according to.