GB2494674A

GB2494674A - A connection formed under water between a wind turbine tower and a wind turbine foundation

Info

Publication number: GB2494674A
Application number: GB1115961.3A
Authority: GB
Inventors: Peter Ronald Chambers
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-09-15
Filing date: 2011-09-15
Publication date: 2013-03-20
Anticipated expiration: 2031-09-15
Also published as: GB201115961D0; GB2494674B

Abstract

A connection formed under water between a wind turbine tower and a wind turbine foundation. Mounted to the column 2 are brackets 6 which pass around posts 7 which are connected to a base member 3 comprising foundation 4. Enlarging members 8 are connected by swaged, crimped, pegged, wedged or other joints to the posts 7. For pre-loading, jacking members 10 or flanges 110 are operated to load the enlarging member 8 or flange 101 and spreader member 11 bearing on brackets 6 and column 2 with compression force and post 7 with same tension force to connect column 2 to base 3. A plinth extends from the base 3 into the column 2 forming a horizontal shear connection. The combined actions of tension in posts 7 and compression on base 3 and the shear plinth rigidly connect the tower to the foundation. Brackets 6 also increase the columns stiffness, which reduces horizontal deflections of tower.

Description

A connection formed under water between a wind turbine tower and a wind turbine foundation The present invention relates to connections formed under water between a column member comprising a wind turbine tower and a base member comprising a wind turbine foundation, including swaged, crimped, pegged, wedged or othcr joints, for constructing and installing offshore wind turbine assemblies. The present invention describes under water methods enabling the connection of a wind turbine column member to a wind turbine base member.

The present invention provides for the pre-loading of the connections if required.

The present invention increases the stiffliess of a wind turbine tower and reduces horizontal deflections of the tower. The present invention can reduce the effective height and slenderness ratio of a wind turbine tower, which would also reduce the horizontal deflections of the tower.

The present invention provides safe dry man access to the tower below sea level, when installed offshore, and enables the long-term maintenance of the tower to extend the useful life of the tower. The present invention supports the option of installing additional piling to an existing wind turbine at a fbture time to increase the power rating of the wind turbine assembly.

For the descriptions in this specification a wind turbine tower comprises column members assembled to form the tower and a wind turbine foundation comprises base members assembled to form the foundation. For offshore wind turbines the foundation will include the interface with the ground forming the seabed on which the wind turbine assembly is located.

This interface may be piling or a spread footing or some other interface including floating foundation arrangements anchored to the seabed. The column member referred to will be the column member forming the bottom of the tower. The base member referred to will be the part of the foundation to which the column member is connected.

A wind turbine tower may be of constant external diameter; i.e. parallel-sided, or of variable cross section diameter; i.e. tapered.

The column member forming the bottom of the tower may be of constant external diameter or may be tapered. The remaining column members forming the whole height of the tower may be parallel-sided, or may be tapered. The tapering, if provided, of the column members forming the tower may be linear or may not be constant per unit of height.

At present the majority of offshore wind turbine foundations are formed using mono-piles.

Also deployed, but less common so far, there are foundations including some form of gravity base, which are large spread footings sitting on the seabed or on a prepared foundation pad or rock carpet on the seabed. There are also other designs of offshore foundation being developed that have not yet been deployed commercially. All of these foundation options have one feature in common and that is that the tower of the wind turbine assembly is mounted to the foundation at a level above sea level.

For the tower of a wind turbine assembly to be mounted to the foundation at a level above sea level part of the foundation has to extend above sea level and this requires the lifting of the tower onto the foundation, which requires a floating crane or a crane mounted on a jack-up barge. This need for floating cranes or jack-up barges is a serious obstacle to the economic and reliable construction of offshore wind farms at present. This is because floating cranes and jack-up barges are expensive, they have limited availability and are vulnerable to storms, which delays projects, which will also add to installation costs. Also, the operation of offshore cranes and jack up barges for heavy lifting has a higher risk of accident than using alternative floatation methods for assembling wind turbines without heavy lifting.

Some suppliers of the offshore wind turbine industry have responded to this problem by proposing to use gravity base type foundations and to assemble offshore wind turbines at the shore and then float out complete assemblies of foundation and tower which are installed on a prepared foundation pad or rock carpet at the wind farm site. This approach should require no floating cranes or jack-up barges. However, the future size, i.e. the power rating, of complete wind turbine assemblies that can be delivered in this way will be limited by the stability problems associated with towing top heavy high structures in shallow offshore waters, especially near the shore at low tide.

Advocates of the mono-pile rely on pile extensions called transition pieces and extensions that extend above the sea level. These transition pieces and extensions could be incorporated in the tower but the whole assembly would still require a floating crane or jack-up barge to lift the transition piece and the extension piece and the tower onto the mono-pile to form the tower to foundation connection.

The present invention provides for the connection between the wind turbine tower and the foundation to be formed under water, by way of example only, at or adjacent to the seabed level of the foundation. This enables floatation methods to be used to mount the tower to the foundation and thus avoids the need for floating cranes or jack-up barges and heavy lifting. It is envisaged that the present invention will be used in depths of water ranging from 25m to 60m. However, a greater range of depths of water, i.e. less deep or deeper, could be accommodated.

The present invention provides for the future maintenance of a wind turbine tower in-situ at the location of the wind turbine within an offshore wind farm. Current offshore wind turbine design practice for steel towers is to assume a relatively short life for the tower relying on the original paint specification, plus possibly some form of cathodic protection, to provide a nominal 20 years anti-corrosion protection. After 20 years it is assumed the amortization of the tower has been cleared and new wind turbine technology will require a new tower, the old one being scrapped.

However, for the much larger towers enabled by the present invention much longer life expectancy will be available because being larger the problems of metal fatigue which limits the useful life of towers can be overcome. It is anticipated that the upper maximum upper limit for the rated power of future offshore wind turbines will be of the order of 25 to 30MW.

This will require, by way of example only, a tower height of 180 to 200m, which is considered the maximum practical and economic height for offshore towers. Towers of this height could then be re-fitted with new generators incorporating new turbine technology and improved blades many times over a lifespan of 100 years plus for the tower. This is consistent with economy and the need to achieve the maximum possible sustainable re-use of materials.

A-

To achieve a reliable 100 years plus lifespan for a steel tower will require on site maintenance below sea level. The present invention will enable this by providing a temporary cofferdam with a roof over to be installed around the tower standing in the sea. The seawater within the cofferdam will be removed by pumping and dry man access provided for the maintenance of or replacement of the original anti-corrosion system applied to the tower.

The present invention is an important invention because the use of floating cranes and jack-up barges is a major obstacle to the economic and safe deployment of offshore wind turbines.

Also, the continuing need for cranes and jack-up barges will limit the possibilities for constructing wind turbines larger than today's size of wind turbine. For example, ftiture wind turbines could be of 20MW power rating compared with 5MW wind turbines, which are regarded as large wind turbines at present. To install bigger offshore wind turbines would require bigger floating cranes and jack-up barges than are available today, and which may not become available or may not be economic or safe to operate, in the future.

Bigger floating cranes and jack-up barges, if made available, would magnif' the technical and operational difficulties, especially the delays due to storms and bad weather, already experienced with the operation of current cranes and jack-up barges.

The present invention is Ibture-proof because larger capacity connections between towers and foundations can be formed by increasing the number of connections used per wind turbine assembly or by using larger components for forming the connections.

The present invention is a novel way of forming the connections required for the construction and installation of wind turbine towers and foundations under water. This has not been done before in the offshore wind turbine industry.

Furthermore, in the case of a piled wind turbine foundation, the details of the embodiment of the present invention shown on the figures included in this specification facilitate the initial load carrying capacity of the foundation to be increased if required. Additional piles can be installed at a time afler the initial installation of the foundation piling. This is possible where the detail adopted for the connecting posts, see below, and for the piling, is an open circular steel tube and therefore further additional piles can be driven down inside the tubes forming the original piling and swaged to the tops of the original piling.

This facility supports the option of upgrading the whole wind turbine assembly to provide greater generating power as new generating technology emerges while still using all the existing structure. The upgrading could consist of post tensioning the tower with stressing cables and jacking to increase structural capacities and fitting a new more powerful rotor, and more efficient blades, drive train and generator. This would be consistent with economy and the need to achieve the maximum possible sustainable re-use of materials.

The embodiments of the present invention described in this specification increase the second moment of area of the horizontal cross section of the column member. This has the beneficial effect of making the tower comprising the column member stiffer and this reduces the horizontal deflection of the tower throughout the height of the tower for any given horizontal loading. This improves the structural performance of the whole wind turbine assembly and enables a more economic tower to be designed for a given size, i.e. power rating, of wind turbine. The increased stifihess also enables higher towers to be considered practical to build because the greater stifthess available enables a tower of smaller diameter and less weight of structural material, e.g. steel, to be used for a given required height of a tower.

The application of pre-loading (see below) to the connections and the column member at an intermediate level above the level of the top of the base member reduces the effective height of the tower. A reduction in effective height of the tower provides the same benefits as increasing the stifthess of the column member as described in the previous paragraph.

Different embodiments of the present invention are described in detail in this specification and other embodiments are referred to. The Figure 1 included in the Abstract illustrates the main features of the present invention described in this introduction part of the specification.

A list of the figures follows this introduction.

For an offshore wind turbine assembly, the connection between the column member forming the bottom of the tower and the base member to which this column member is connected has to have the capability of transferring from the tower into the base all the vertical forces (self-weight) and bending (overturning effects) moments and lateral forces (horizontal shear) arising from the action of wind and waves on the wind turbine assembly.

The self-weight of the wind turbine assembly acts vertically downwards and is transferred directly from the tower to the base by the direct bearing of the column member, and the bracket members if extended to contact the base member as described below, onto the base member.

The bending moments are overturning effects due to the action of the wind and wave forces on the wind turbine assembly. The bending moments act in vertical planes passing through the wind turbine assembly aid these vertical planes can be aligned in any direction. The bending moments can be converted into vertical forces acting upwards and downwards acting as a couple across the effective width of the group of connections between the column member and the base member, as would be understood by a designer familiar with the design of wind turbine foundations.

The vertical forces acting downwards are transferred directly from the tower to the base by the direct bearing of the column member and the bracket members, if extended to contact the base member, as described below, onto the base member. The vertical forces acting upwards are transferred from the tower to the base by connections joining the column member to the base member as described below.

The lateral forces are the horizontal shear forces due to the action of the wind and wave forces on the wind turbine assembly and can act in any horizontal direction. For designing the connections comprising the present invention to transfer horizontal shear forces there ate three options.

A first option is that all the horizontal shear forces are assumed for design purposes to be transferred by the direct bearing of the wall of the column member onto a raised concrete plinth (described below) mounted to and extending from the base member.

A second option is to assume that some of the horizontal shear will be transferred by the shear resistance of the vertical connections between the column member and the base member and also by the friction generated between the column member, and the bracket members if extended to contact the base member, and the base member. The remaining portion of the lateral forces, that is not transferred through the connections or by friction, would be transferred by the raised plinth. (as already described above, and below) A third option is that all of the horizontal shear will be transferred by the shear resistance of the connections between the column member and the base member and also by the friction generated between the column member and the bracket members, if extended to contact the base member, and the base member. For this third option a raised plinth mounted to the base member would not be required.

For the embodiments of the present invention described in the following specification a raised plinth mounted to the base member is provided and so options one and two are available and option three is redundant.

Although option three may appear simpler to construct and would be possible, the horizontal shear forces to be transferred are large, especially wave forces in storm conditions, by way of example only, 1,500 plus tons, and consequently it would be difficult to design connections that are stiff enough to transfer all of the shear forces.

Vertical / longitudinal shear also occurs in the components of the connections and in the wall of the column member. This vertical I longitudinal shear is resisted and transferred by the inherent shear strength of these elements.

The connections between the column member arid the base member therefore have to resist vertical forces, tension acting upwards on the base member and compression acting downwards on the base member, and horizontal shear forces acting horizontally on the base member in any direction.

To resist vertical forces, the embodiments of the present invention described here utilize a group of connections between bracket extension members mounted to the column member and connecting post members anchored into the base member. The bracket extension members fit over and around the connecting post members anchored into the base member.

Two embodiments of connecting posts are described in this specification, referred to as A and B. These two embodiments of the connecting posts enable different methods of pre-loading.(see below) the connections to be used. These methods of pre-loading are also referred to as A and B (see below)

B

To resist horizontal shear forces the embodiments of the present invention described here include a shear transfer structure in the form of a raised plinth extending from the base member into the bottom part of the column member.

It is very important that under normal service conditions that all of the components of the connections joining the column member to the base member remain in close contact and that there is no relative movement between adjoining surfaces and no opening of gaps between joint components. This can be achieved by pre-loading the connections at the time of assembly before service loads are applied.

Pre-loading generates forces in the joint components prior to the service loads being applied to the joint. The required forces to pre-load the joint components can be generated by a temporary jacking system incorporated within the assembly of components forming the joint.

The tension forces generated by applying pre-loading are balanced by the tension forces generated by the service loads. There is no increase in the total external force applied to the joints but forces within the joint are modified and compression stresses are increased in service.

The main benefits of pre-loading are as follows: Pre-loading ensures that the column member and the bracket members if extended to contact the base member, are pressed down into solid contact with the base member during the assembly and mounting of the tower to the base and precludes vertical movement occurring due to subsequent settlement or gap closing between the column member and the base member when the frill service loads are applied.

Pre-loading increases the friction forces available to resist lateral loads.

Pre-loading reduces the movement and possible separation of the joint components under service loads Pre-loading enhances the fatigue life of components.

Pit-loading can reduce the effective height and slenderness ratio of the wind turbine tower significantly. By way of example only, for a 130m high tower for a 5MW turbine in the North Sea, from an effective height of l3Om to horn, which is a 15% reduction.

For the embodiment of the present invention described in the following specification pre-loading is incorporated. It is anticipated that for most applications of the present invention pre-loading will be required. None-the-less, other embodiments of the present invention may be used that do not include pre-loading and these embodiments would not require a jacking system.

The specification here describes in detail two methods, referred to as A and B of pre-loading applied at different stages during the formation of the underwater connection and incorporating two embodiments of the connecting posts referred to as A and B. For connecting posts embodiment A the pre-loading is applied at an intermediate level of the post A and after the jointing process. For connecting posts embodiment B the pre-loading is applied at or near the top of the post B and before the jointing process. There are advantages and disadvantages with the two methods as follows: The advantage of using embodiment A for the connecting posts and pre-loading is that the pre-loading force is applied after the formation of the joint and so any slip that occurs in the joint when it is loaded can be taken up and the required pre-loading force can be developed, applied and measured. The pre-loading force will be accurately known which is important from the warranty aspect of certifying the wind turbine assembly.

The disadvantage of using embodiment A for the connecting posts and pre-loading is that packing has to be installed between the spreader plate member and the post enlarging member above to maintain the required pre-loading force before the jacks can be removed.

Installing packing will be a time consuming task to be carried out underwater. However, a possible benefit of installing packing is that the jacks can be reinserted and the pre-loading force amended if required and thicker packing inserted to preserve the increased pre-loading force. Furthermore, it would be possible to amend the pre-loading at a later date.

The advantage of using embodiment B for the connecting posts and pre-loading is that the jacks can be removed without the need for packing because the pre-loading force is locked in by the formation of the joint.

The disadvantage of using embodiment B for the connecting posts and pre-loading is that the pre-loading force is applied before the formation of the underwater joint and so any slip that occurs in the joint when it is loaded has to be estimated and the required pre-loading force increased to allow the loss of force due to slippage in the joint when the jacks are removed.

Another disadvantage is that the pre-loading force cannot be easily increased because the initial force is locked in to the formed joint.

By way of example only. The pre-loading force required to be applied to one connecting post could be 800 tons and the slippage occurring within the under water joint when subject to this load could be 33%. Therefore to accommodate this slippage and to ensure that the required permanent service pre-loading is provided, the initial pre-loading applied by the jacks to a connecting post B would need to bel200 tons.

The advantages and disadvantages of embodiments of the connecting posts and pre-loading methods A and B are of similar merit and the choice of embodiment adopted will be determined by engineering judgement based on the pre-loading required for specific designs of wind turbine assemblies.

Other methods of pre-loading the connections included in the present invention could be used and other embodimcnts of the present invention could use the methods described here or other methods.

For the transfer of horizontal shear force, the embodiments of the present invention described in this specification includes shear transfer structures in the form of a raised plinth extending from the base member. This plinth is structurally mounted to the base member and is an integral part of the base member. The plinth is located inside the bottom of the column member, which is fitted over the plinth when the column member is lowered onto the base member during the mounting of a wind turbine tower to a wind turbine base at an offshore location.

When the column member is located over the plinth there remains a space provided between the plinth and the inside face of the wall forming the column member. When the column member has been adjusted to be in the correct location standing on the base member the remaining space around the plinth between the plinth and the inside face of the wall of the column member, is filled with solid material, for example concrete.

By way of example only, this space could be approximately Im wide and Im high, corresponding to a Im.high plinth, extending to a height of 1 m above the top surface of the base member. The space extends around the whole perimeter of the plinth and may be divided into sections by cross walls. As the connection forming the present invention is formed under water the space is initially filled with water, This water is displaced by the material used to fill the space, for example concrete, which can be placed under water.

Overflow holes are provided in the column member floor slab to enable water to be expelled from the space around the raised plinth. These same overflow holes allow the concrete to overflow when the space has been filled with concrete and this overflow of concrete, which can be observed by remote TV cameras, indicates when the space has been filled and the concrete supply can be stopped.

The overflow holes are formed in the floor slab forming the bottom floor of the column member. This floor slab stiffens the column member and is also required to make the column member and associated column members forming the tower a watertight structure that has positive buoyancy and will float in water. This self-buoyancy assists with the delivery of the tower to the wind turbine assembly site using floatation methods. This self-buoyancy also assists with the mounting of the tower to the base and the delivery of the wind turbine assembly to the final wind turbine location at a wind farm.

To preserve the water tightness of the column member and the tower, the overflow holes described above are initially sealed using removable plugs. The plugs remain in place until the column member has been mounted to the base member. At this stage the horizontal joint between the bottom edge of the column member and the top surface of the base member will be made watertight and so the plugs are no longer required to keep the column member and the tower watertight. (2.

The concrete filling of the space around the raised plinth, between the plinth and the inside face of the wall of the column member, can be carried out using a pumped concrete system installed on a concrete supply ship on the sea surface, adjacent to the wind turbine being assembled. Pump grade concrete is manufactured in a concrete mixing plant on board the ship and is delivered via delivery pipes extending down the out-side face of the wall of the column member and passing through the wall of the column member and discharging into the space to be filled. There can be more than one delivery pipe spaced around the perimeter of the column member to ensure even delivery of concrete into the whole length of the space around the perimeter of the raised plinth.

The concrete filling will displace water from the space to be filled through the overflow holes into the inside of the column member where excess water can be accommodated until it is convenient to discharge the water out to the sea.

Concrete delivery continues until concrete flows up out of all of the overflow holes in the column member floor slab (as described above and below) at a steady rate equal to the concrete delivery flow. This condition, i.e. concrete delivery and overflow are the same, indicates that the space is fUll of concrete. The volume of the space and the volume of the concrete delivered are also to be reconciled. When the space has been filled with concrete, then concrete delivery is stopped and the concrete within the space is allowed to set. As soon as delivery ceases the delivery pipelines, which at this stage will be fUll of wet concrete, are sealed by closure of valves, disconnected. recovered, emptied and cleaned for re-use. There is space inside the column member above the floor slab to accommodate the overflow concrete.

Concrete pumping technology is now a well-developed technology serving the construction industry. It is common practice nowadays in the building construction industry for concrete to be pumped over long distances and great heights, 300m for example, much further than the distance required for the present invention, for example I OOm. The concrete mix is designed to be fluid, suitable for pumping, and will have delayed set characteristics enabling the whole of the filling operation to be completed before the concrete starts to set. The concrete filling displaces water that may initially fill the space. (3

In another embodiment of the present invention the raised plinth described above may be formed by other structural arrangements of the interface between the column member and the base member. For example, the function of the raised plinth described above may be provided by a continuous circular rebate formed in the upper surface of the base member within which the bottom of the column member wall is located. The space between the column member wall and the sides of the rebate is filled solid with concrete using similar concreting methods to those already described. The details of the bottom of the bracket members would have to be modified to accommodate the rebate.

In another embodiment of the present invention, the frmnction of the raised plinth described above may be provided by a continuous circular upstanding cantilever structural wall mounted to the upper surface of the base member. The bottom of the column member wall would be located within the circular wall and the space between the wall and the wall of the column member is filled solid with concrete using similar concreting methods to those already described. The details of the bottom of the bracket members would have to be modified to accommodate the continuous circular upstanding cantilever structural wall mounted to the upper surface of the base member. As an alternative the wall could be located inside the column member. This arrangement would be essentially the same as the upstanding plinth already described.

For the descriptions used in this specification, the words....or equivalent enlarging member' refer to any alternative detail mounted to or incorporated in and comprising the...post members anchored into the base member' that enlarges the perimeter of the post member and engages with the spreader members or jacking system and enables force to be transferred to the post.

According to a first aspect of the present invention there are swaged, crimped, pegged or wedged or other type of joints formed under water incorporated in a connection between a wind turbine column member and a wind turbine base member. Possibly there is a plurality of post members anchored into the base member and extending upwards from the base member. Possibly the post members are steel tubes of circular cross section or they may be of solid material and may be of a non-circular cross section.

Possibly there are embodiments of the present invention in which there are two different types of post members referred to here as A and B. Post member embodiment B includes an annular collar member or equivalent enlarging member mounted to the top end of the post or adjacent to the top end of the post forming a flange or sections of a flange around the post.

This flange may be formed as an integral part of the post at the same time as the post is formed or it may be formed using a machining or other fabrication process. Post member embodiment A does not include this flange detail.

Possibly the base member is of reinforced concrete or steel construction or hybrid steel and concrete construction. Possibly the column member is of steel construction or of hybrid steel and concrete hybrid According to a second aspect of the present invention there are bracket members mounted to and extending from the column member, comprising a wind turbine tower, mounted to a wind turbine base member. Possibly the bracket members are of steel construction and are mounted to the column member, which is of steel or steel and concrete construction, by welding. The column member is positioned on the base member and the bottom edge of the walls of the column member and the bottom edge of the bracket members bears on the base member. Possibly the bottom edge of the bracket members is chamfered in which case the bracket members do not bear directly on the base member.

According to a third aspect of the present invention the brackets mourned to the column member extend alongside the post members embodiments A or B extending from the base member. Possibly there are steel spreader members in the form of a plate, which may be formed using cast steel, bearing onto the brackets, there being a hole in the middle of the spreader members through which the post member A or B extending from the base passes. Or possibly the post members A or B extending from the base member pass between or adjacent to linear spreader members bearing on the brackets.

Possibly the spreader members, when initially placed onto the bracket members, can be moved in plan relative to the bracket members and so can accommodate unsymmetrical alignment between the bracket members and the post members extending from the base and the size of the spreader member is such that it always extends to cover the bracket members Is and bear on the bracket members and may overhang the bracket members at some locations so as to be able to transfer forces onto the bracket members in a stable and effective manner.

According to a fourth aspect of the present invention there is an annular collar member or equivalent enlarging member mounted to the post members embodiments A or B extending from the base. This annular collar member or equivalent enlarging member is located above the spreader member, which sits on top of the bracket members extending from the column member. This annular collar member or equivalent enlarging member is initially not joined to the post members A and B. According to a fifth aspect of the present invention, a set of jacks is included arranged around the external perimeter of the post members embodiments A and B extending from the base. If pre-loading is not required then these jacks are not required.

For embodiments comprising posts A the set of jacks is located between the spreader members and the lower edge of the annular collar members or equivalent enlarging members.

For embodiments comprising posts B the set of jacks is located between the lower edge of the annular collar members or equivalent enlarging members in the form of a flange around the top end of the post B and the upper edge of the annular collar members or equivalent enlarging members bearing on the spreader members.

According to a sixth aspect of the present invention there is a method whereby a swaging tool, a crimping tool, pegs or wedges are applied or installed to the post members A or B extending from the base member or to the collar members or equivalent enlarging members located around the post members A or B extending from the base member to form a swaged, crimped, pegged or wedged joint between each of the post members A or B extending from the base member and the associated annular collar members or equivalent enlarging members. The stage at which this joint is formed is different for posts A and B, see below.

The components comprising the joint will be made large enough to enable the joint to transfer the forces applied to the joint without any relative movement occurring between the components forming the joint. (6

According to a seventh aspect of the present invention the set of jacks arranged around the external perimeter of the post members A or B extending from and anchored into the base member are operated so as to extend and put compressive force onto the annular collar members or equivalent enlarging members and onto the spreader members. The stage at which the jacks are operated is different for the two embodiments of post members A and B. For posts embodiment A the jacks are operated after the jointing described in the sixth aspect described above has been completed. For posts embodiment B the jacks are operated before the jointing described in the sixth aspect described above has been completed.

For posts embodiment A the annular collar members or equivalent enlarging members transfer the applied compressive force generated by the operation of the jacks onto the post members extending from and anchored into the base member to which they are joined. The post members extending from and anchored into the base members become tensioned by a force equal in size to the compressive force on the annular collar members or equivalent enlarging members, the tension force is resisted by the anchorage of the post members extending from and anchored into the base member.

The extended jacks put the same size compressive force onto the spreader members, which transfer the compressive force onto the bracket members mounted to the column member and this force is transferred to the column member which transfers the compression force onto the base member by bearing on the base member. Part of this force will also be transferred onto the base member by the bearing of the bottom edge of the bracket members onto the base member if the bracket members are extended to bear on the base member.

For posts embodiment B the annular collar members or equivalent enlarging members forming a flange around the top of the post B transfer the applied compressive force generated by the operation of the jacks onto the post members extending from and anchored into the base member.

The extended jacks put the same size compressive force onto the annular collar members or equivalent enlarging members located around post embodiment B but at this stage not joined to post embodiment B, which transfer the compressive force onto the spreader members bearing on the bracket members mounted to the column member and therefore this force is transferred to the column member which transfers the compression force onto the base member by bearing on the base member. Part of this force will also be transferred onto the base member by the bearing of the bottom edge of the bracket members onto the base member if the bracket members are extended to bear on the base member.

In this way, the tension force in the post members, both A and B, extending from and anchored into the base member, is balanced by the compression force put onto the base member from the column member and the bracket members if the bracket members are extended to bear on the base member.

According to an eighth aspect of the present invention the forces exerted by the extendable jacks are measured and the force is increased until it is of the required value corresponding to the required pre-loading of the connection.

For post embodiment A: When the stage described in the eighth aspect has been reached the jacks are made solid and will then not extend further or contract. Possibly the jacks are made solid by injecting a resin into the jacking mechanism which sets solid and so prevents further movement of the jack but this also makes the jacks of no further use and is therefore uneconomic in most cases.

Possibly, as an alternative to locking the jacks with resin, which renders the jacks unusable, when the force applied by the jacks is of the required strength, then solid packing, steel plate for example, is introduced between the annular collar members or equivalent enlarging members and the spreader members enabling the jacks to be relaxed and recovered for re-use.

The packing maintains the spacing between the annular collar members or equivalent enlarging members and the spreader members thus maintaining the tension force in the post members extending from and anchored into the base member and the corresponding compression force bearing on the spreader members and bracket members. As an alternative to solid steel packing, hollow resin filled packs could be used or any other suitable packing system. This packing process would be carried out under water by an attending remotely controlled vehicle.

For post embodiment B. Only when the stage described in this eighth aspect has been reached are the annular collar members or equivalent enlarging members located around post B joined to post B. After this the jacks can now be released without the need for packing as the force generated by the jack will be transferred onto the spreader members by the annular collar members or equivalent enlarging members now joined to post B. To allow for slippage in the joint the original jacking force is increased pro-rata to allow for the amount of slippage predicted, for example, by trial jacking on test pieces including swaged joints.

According to a ninth aspect of the present invention there is a raised plinth extending from the base member into the bottom of the column member. Possibly this plinth is structurally continuous with the base member or is mounted to the base to be structurally continuous with the base member. During the procedure of mounting the wind turbine tower to the turbine foundation the column member is moved into position over the raised plinth and is lowered onto and is supported by the base member. The column member is located symmetrically around the raised plinth and there remains a space around the plinth between the outer perimeter of the plinth and the inner face of the wall of the column member. When the column member is correctly positioned and has been mounted to the base member the space between the plinth and the wall of the column member is filled solid, possibly with concrete, which is delivered by pipeline from a ship on the surface.

According to a tenth aspect of the present invention the column member is rigidly connected to the base member by the combined action of the following three actions.

1) The swaged, crimped, pegged or wedged or other joints between the annular collar members or equivalent enlarging members and the post members extending from and anchored into the base member.

2) The vertical bearing of the column member onto the base member and of the bracket members if also bearing onto the base member.

3) The horizontal bearing of the column member on the raised plinth extending from the base member into the column member. Is

This combination of three actions prevents the column member moving relative to the base member in any direction, neither vertically nor horizontally.

According to an eleventh aspect of the present invention there is provision in the design of the spreader plate members to accommodate the inevitable errors in the positioning of the column member relative to the base member and errors in the manufacture of components.

The provision of oversized spreader plate members, which can be moved around in plan to suit the position of the post members, maintains filly effective bearing by the spreader plate members onto the bracket members while accommodating errors in the dimensional relationship between components and errors in positioning the column member on the base member.

According to a twelfth aspect of the present invention safe man access is provided for the maintenance of the wind turbine tower and the components forming the connections between the column member and the base member, offshore at the wind farm site. Possibly this access is provided using a demountable cofferdam to be installed temporarily around the wind turbine tower comprising the column member. The cofferdam will be mounted to the top of the base member and the joint between the cofferdam and the top of the base member will be made watertight. The cofferdam will extend in height from the top of the base member to a level sufficiently above sea level to prevent seawater over topping the top edge of the cofferdam. The cofferdam will be drained of seawater by pumping and provided with a roof to create a dry working environment for the maintenance of the column member and the connections. The arrangement of the connecting posts and the spacing of the bracket members will allow sufficient space for safe man access to these members to facilitate maintenance According to a thirteenth aspect of the present invention, possibly in the case of a piled foundation the initial load carrying capacity of the foundation can be increased if required by installing additional piles at a time after the initial installation of the foundation piling. This is possible because the detail adopted for the connecting posts, see below, and for the piling is an open circular steel tube and therefore further additional piles can be driven inside the tubes forming the original piling and swaged to the tops of the original piling..

Embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings including figures Ito 17.

The embodiments of the present invention described here and illustrated in the accompanying drawings comprise a wind turbine column member that may be of single steel plate wall construction or of twin steel plate wall construction with concrete inflil between the twin steel plates forming the wall or of concrete construction or of a combination of steel and concrete construction. The column member may be of constant external overall diameter or may be tapered and of varying external overall diameter.

The wind turbine column member is mounted to a wind turbine base member of reinforced concrete construction or of steel construction or of hybrid steel and concrete construction.

The part illustration of a base member shown in figures 1 to II represents part of a base member that comprises an undefined wind turbine foundation that can be a piled foundation, gravity base spread footing with or without skirts penetrating into the sea bed or a suction bucket type of foundation or a floating base with restraining anchors or a framed jacket type of foundation or any other design of foundation suitable for an offshore wind turbine assembly.

Figures 12 to 15 illustrate, by way of example only, base members that comprise a defined piled foundation.

Figures 16 and 17 indicate typical swaged joints between circular steel tubes.

For the embodiment of the present invention shown in the following figures the joint between the annular collar member or equivalent enlarging member and the post member extending from and anchored into the base member as illustrated is a swaged joint. Other embodiments of the present invention could be drawn showing swaged, crimped, pegged or wedged or other joints between different annular collar members or different equivalent enlarging members and the post members extending from and anchored into the base member.

Furthermore, for the embodiment of the present invention shown in the following figures the post member extending from and anchored into the base member illustrated is a circular tube. 2.1

Other embodiments of the present invention could be drawn with the post members extending from and anchored into the base member being of different cross section shape, also solid sections of various profile shape could be used.

For each of the possible different sections that could be used for the post members extending from and anchored into the base member there would be a specific design of swaged, crimped, pegged or wedged or other joint between the annular collar member or other equivalent enlarging members and the post member extending from the base member.

A list of the 17 figures describing embodiments of the present invention now follows.

There are two embodiments of the present invention illustrated in the figures in which there are two different types of post members referred to as A and B differentiated in the figs numbers as 7A, 8A, I 4A and I 5A for post A and 7B, 8B, 14B and I SB for post B. Post B includes an additional annular collar member or equivalent enlarging member mounted to the top end of the post or adjacent to the top end of the post forming a flange or sections of a flange around the post. Post members A do not include this flange detail.

Figure 1 is a typical representative perspective view of a group of swaged connections arranged around the bottom perimeter of a parallel-sided wind turbine column member of constant external overall diameter, mounted to part of an undefined wind turbine base member comprising an undefined wind turbine foundation.

Figure 2 is a typical representative perspective view of a group of swaged connections arranged around the bottom perimeter of a tapering wind turbine column member that is not a parallel-sided wind turbine column member of constant external overall diameter, mounted to part of an undefined wind turbine base member comprising an undefined wind turbine foundation.

Figure 3 is a cross sectional elevation view as indicated by the inclined arrows marked Al -Al on fig.l showing a parallel-sided wind turbine column member of constant external overall diameter. This view shows 7 swaged connection joints in the elevation, which would correspond to a fill perimeter group of 12 swaged connection joints arranged around the 2.2 perimeter of the column member. Also shown dotted is the location of the temporary cofferdam used to provide dry safe access for maintenance of the tower.

Figure 4 is a cross sectional elevation view as indicated by the inclined arrows marked A2-A2 on fig.2 showing a tapering wind turbine column member of variable external overall diameter. This view shows 7 swaged connection joints in the elevation, which would correspond to a frill perimeter group of 12 swaged connection joints arranged around the perimeter of the column member. Also shown dotted is the location of the temporary cofferdam used to provide dry safe access for maintenance of the tower.

Figure SA is a plan section view as indicated by the arrows marked Bl-Bl on fig.l for a wind turbine assembly in which the column member is parallel-sided of constant external overall diameter mounted to part of an undefined wind turbine base member. In this example there are ten swaged connections shown mounted to the perimeter of the column member.

Figure 5B is a larger scale plan of part of fig SA and shows details of the connections and the location of the temporary access cofferdam provided for maintenance of the tower.

Figure GA is a plan section view as indicated by the arrows marked B2-B2 on fig.2 for a wind turbine assembly in which the column member is tapered of varying external overall diameter mounted to part of an undefined wind turbine base member. In this example there are twelve swaged connections shown mounted to the perimeter of the column member.

Figure 6B is a larger scale plan of part of fig.6A and shows details of the connections and the location of the temporary access cofferdam provided for maintenance of the tower.

Figure 7A is a cross section elevation view as indicated by the arrows marked Cl-C] on fig. SA for a wind turbine assembly in which the column member is parallel-sided of constant external overall diameter and includes post members embodiment A. Figure 7B is the sante as fig. 7A but including post members embodiment B, which include a top flange detail.

Figure SA is a cross section elevation view as indicated by the arrows marked C2-C2 on fig.6A for a wind turbine assembly in which the column member is of tapering cross section of variable external overall diameter and includes post members embodiment A. Figure 8B is the same as fig. 8A but including post members embodiment B, which include a top flange detail.

Figure 9 is a cross section plan view as indicated by the arrows marked Di-DI on figs. 7A and 14A, i.e. applicable to a parallel-sided column member.

Figure 10 is a cross section plan view as indicated by the arrows marked D2-D2 on figs. SA and 15A, i.e. a column member of tapering cross section.

Figure 11 is a cross section plan view as indicated by the arrows marked E-E on figs.7A, SA and figs. 14A and ISA. For figs.14A and iSA examples of additional piling within the posts forming the connection are shown.

In figs 7A, 8A, I 4A, ISA (which are vertical sections) and 11 (which is a plan section at the bottom of the column members), the wall of the column members 2 is indicated by two lines indicating the thickness of the wall that is shown in these five sections through the wall of the column member 2 as drawn. However, in figs. 9 and 10, (which are plan sections at an intermediate level) the wall of the column members 2 is shown by a single line indicating only the outer face of the wall. This is intended to illustrate the difference between the details associated with the parallel-sided column member in fig 9 and the tapering column member shown in fig. 10. The two circumferential lines in fig 10 indicate upper and lower points on a sloping column member wall whereas the single circumferential line in fig. 9 indicates the outer face of the column member wall that is vertical.

Figure 12A is a plan section view similar to fig.SA but in which a wind turbine column member with a parallel-sided cross section is connected to a wind turbine base member comprising a defined piled foundation for a wind turbine assembly by means of ten swaged connections. The layout of the column member and the swaged connections is not symmetrically related to the layout of the piles comprising the piled foundation.

In this plan the perimeter of the base is defined and the location of piles are shown. If required, ten additional piles can be added to the foundation by installing one pile through each of the vertical mbular post members of the swaged connections.

Figure 12B is a larger scale plan of part of fig 12A and shows details of the connections and the location of the temporary access cofferdam provided for maintenance of the tower.

Figure l3A is a plan section view similar to fig.6A but in which a wind turbine column member with a tapering cross section is connected to a wind turbine base member comprising a defined piled foundation for a wind turbine assembly by means of twelve swaged connections. The layout of the column member and the swaged comiections is symmetrically related to the layout of the piles comprising the piled foundation.

In this plan the perimeter of the base member is defined and the location of piles are shown.

If required, twelve additional piles can be added to the foundation by installing one pile through each of the vertical tubular post members of the swaged connections.

Figure 13B is a larger scale plan of part of fig l3A and shows details of the connections and the location of the temporary access cofferdam provided for maintenance of the tower.

Figure 14 A is a cross section elevation view as indicated by the arrows marked Fl-Fl on fig. 1 2A for a wind turbine column member with a parallel-sided cross section and includes post members embodiment ref.A.

Figure 14B is the same as figl4A but including post members ref B, which include a top flange detail.

Figure 15 A is a cross section elevation view as indicated by the arrows marked F2-F2 on fig. 13A for a wind turbine column member with a tapering cross section and includes post members embodiment ref.A.

Figure 1 SB is the same as fig. ISA but including post members ref B, which include a top flange detail.

Both figs.14A and 15A show the possible location of piles generally located within a defined piled foundation as described in the present invention. These sections also show the possibility of inserting piles through the vertical tubular post members A and 13 comprising the swaged connection described in the present invention. This facility, if used, increases the number of piles that can be accommodated within a base member of a given size comprising a wind turbine piled foundation.

Figure 16 shows details of a typical swaged joint between two steel tubes, one tube fitting inside the other. This type of swaged joint is one of the proposed methods for joining the annular collar member 8 to the post member 7 in accordance with the present invention as described in the previous figs. I to 15 Figure 17 is a section showing a swaged joint similar to the swaged joint shown in fig 16 applied to the general piling for a wind turbine piled foundation as described in the previous flgs.12 to 15.

There now follows a detailed description of the 17 figures in which: Figure 1 is a typical representative three-dimensional sketch showing in a perspective view the main components of an embodiment of the present invention comprising a wind turbine assembly in which the bottom part of the tower is parallel-sided. The sketch shows the lower part of the tower of a wind turbine assembly 1 comprising a wind turbine column member 2 mounted to part of a wind turbine base member 3 comprising a wind turbine foundation 4, the foundation being of undefined design and size.

By way of example only, the foundation 4 could be a gravity spread footing or a piled foundation, the base member 3 comprising a spread footing in contact with the ground or comprising a pile cap to which piles are connected or any other type of wind turbine foundation. The present invention could be used for an onshore or offshore wind turbine assembly.

However, the more likely application of the present invention will be for offshore wind turbines where the advantage of being able to construct underwater the connection between a wind turbine column member and base member is advantageous. Also the increasing size of 2é offshore wind turbines will require column member to base member connections that are potentially able to transfer larger forces than can be accommodated by current practice designs.

Fig I shows five number swaged connections visible in the elevation view indicated by arrows 5. There is no particular significance to showing 5 connections. For each connection one pair of brackets 6 are mounted to the outer face of the wall of column member 2 and embrace the vertical tubular post members 7. Also shown are the annular collar members 8 around the external perimeter of the vertical post members 7 and the location of spreader members II.

Two embodiments of post member 7 are shown. To the left of the figure embodiment ref A is shown and the post 7 does not include a top flange and the set of jacks 1 0 is located below annular collar member 8. To the right of the figure is shown embodiment ref B and the post includes a flange 101 at the top of the post 7 and there is an alternative location for the set of jacks 110 below this flange 101 and above annular collar member 8. These two embodiments of post 7 and corresponding locations of jacks are repeated in the figures where these two components occur.

Fig. 1 shows the main details and layout of the components of the present invention and there is no particular significance to the relative sizes or proportions of the components as drawn or the cross section profiles of the components.

The sectional elevation indicated by inclined arrows Al-Al is shown in fig. 3. The section plan indicated by the arrows BI-BI is shown on fig.5A Figure 2 is a typical representative three-dimensional sketch showing in a perspective view the main components of an embodiment of the present invention comprising a wind turbine assembly in which the bottom part of the tower is of tapering cross section. The detail descriptions for fig. 2 are the same as for fig. 1.

The sectional elevation indicated by inclined arrows A2-A2 is shown in fig. 4. The section plan indicated by the arrows B2 -B2 is shown on fig.6A.

Figure 3 is a cross sectional elevation view as indicated by the inclined arrows marked Al -Al on fig. 1 showing a parallel-sided wind turbine column member of constant external overall diameter.

This view shows 7 swaged connection joints 5 in the elevation, which would correspond to a full perimeter group of 12 swaged connection joints 5.

The present invention can include any required number of swaged connections. The 7 connections 5 shown here in elevation correspond to a wind turbine assembly in which there are 12 swaged connections arranged in plan around the perimeter of the column member forming the connection between the wind turbine column member and the base member.

By way of example only. If 914mm diameter circular steel tubes with a wall thickness of 30mm were provided as the post member 7 extending from and anchored into the base member forming the twelve swaged connections mounted to the column member then this detail would correspond to the connection required between the column member and base member comprising a typical 5MW offshore wind turbine assembly installed in North Sea conditions and standing in typically 35m to 45m depth of sea.

More detail is shown in flg.3 (and fig. 4 below) including the bracket members 6 and the vertical post members 7 extending above the top edge of the annular collar member 8.

The two embodiments of post 7 already described in fig. I are shown along with the corresponding locations of jacks. To the left of the figure post 7 embodiment ref A is shown and the post has no top flange and the set ofjacks lOis located below annular collar member 8. To the right of the figure is shown post 7 embodiment ref B and the post includes a flange 101 at the top of the post 7 and an alternative location for the set of jacks 110 below this flange 101 and above annular collar member 8.

For embodiment A the annular set ofjacks 10 sits on and bears on the spreader members II, which sit on and bear on the bracket members 6. For embodiment B the set ofjacks 110 sits on and bears on the annular collar members 8 which sit on and bear on spreader members 11, which sit on and bear on the bracket members 6. 2.8

Base member 3 is shown in section.

Temporary cofferdam 202 is shown supported by struts 203 bearing onto the vertical wall of column member 2. Cofferdam 202 bears on the top of base member 3 and there is a watertight seal 204 at this junction.

Figure 4 is a cross section elevation view, similar to fig. 3 above, as indicated by the inclined arrows marked A2-A2 on fig. 2 showing a tapering wind turbine column member of variable external overall diameter.

As in fig. 3 this view shows 7 swaged connection joints 5 in the elevation, which would correspond to a full perimeter group of 12 swaged connection joints 5. The comments and notes above as applied to fig. 3 also apply to uig.4.

Temporary cofferdam 202 is shown supported by struts 203 bearing onto the inclined wall of column member 2. Cofferdam 202 bears on the top of base member 3 and there is a watertight seal 204 at this junction.

Figure SA is a plan section view as indicated by the arrows marked B 1-B 1 on fig. 1 for a wind turbine assembly in which the column member is parallel-sided of constant external overall diameter and is mounted to part of an undefined wind turbine base member.

In this example there are ten swaged connections 5 shown mounted to the perimeter of the column member that bears on a foundation of indeterminate design and size.

There is a raised plinth extending from the base member into the bottom part of the column member under the floor slab of the column member. The dotted line circle marked 31 indicates the location of this plinth.

Section Cl -Cl is shown in fig. 7A Figure 5B shows an enlargement of a segment of fig. 5A with the same centre point 201.

This enlarged segment shows post members 7 within bracket members 6 with spaces X and Y between these two members. Spaces X are, by way of example only, 400mm wide to allow man access for maintenance of members 6 and 7. Space Y can be less than 400mm because member 40 is a series of struts and ties, not a continuous plate, therefore affording man access.

Man access is enabled by the installation of a temporary cofferdam 200, which when the sea water has been pumped out provides a dry working space of width Z which can be, by way of example only, of the order of Im to 2m. The provision of the temporary cofferdam and the spacing of the members allows for the maintenance of the tower and connections at intervals of the order of 1 5 to 25 years to further enable the tower having an extended lifespan of 100 plus years.

Figure GA is a plan section view as indicated by the arrows marked B2-B2 on fig.2 for a wind turbine assembly in which the column member is tapered of varying external overall diameter and is mounted to part of an undefined wind turbine base member.

in this example there are twelve swaged connections 5 shown mounted to the perimeter of the column member that bears on a foundation of indeterminate design and size.

There is a raised plinth extending from the base member into the bottom part of the column member under the floor slab of the column member. The dotted line circle marked 41 indicates the location of this plinth.

Section C2 -C2 is shown in fig. SA.

Figure GB shows an enlargement of a segment of fig. 6A with the same centre point 205. The same notes apply as for fig SB above.

The figures 5 and 6 and the following figures 7 to 15 inclusive all illustrate an embodiment of the present invention in which the post members 7 shown extending from and anchored into the base member 3 are tubular members and have a circular horizontal cross section. Tn other embodiments of the present invention, by way of example only, the post members 7 could be of solid section of various profiles, for example an H section steel beam or a Universal Column section or any other suitable section or profile.

In other embodiments of the present invention the post members 7 may not be arranged to be generally vertical and may not be arranged in a circular pattern.

Figure 7A is a cross section elevation view as indicated by the arrows marked Cl-Cl on fig. 5A for a wind turbine assembly in which the column member is parallel-sided of constant external overall diameter.

Fig 7A shows embodiment A of post members 7 extending from the base member 3 and anchored into the base member 3 by fabricated anchor details 20.

Also shown in section are the column member 2, base plinth 21 and the space 22 filled with concrete infill.

The relationship between the annular collar member 8, the set of jacks 10 and the spreader plate member 11 is shown. Also shown is the over-sizing of the spreader plate member shown at 12, where the spreader plate member 11 overhangs the bracket member 6. The over-sizing 12 is to ensure that the spreader plate member can accommodate possible unsymmetrical alignment of the vertical tubular post members 7 passing through hole 23 in the spreader plate member relative to bracket members 6. This aspect is indicated by arrows X and will ensure proper bearing of the spreader plate member 11 on the full width of the plates forming the bracket members 6.

The brackets 6 have several functions. They transfer loads onto and from the column member and they increase the horizontal second moment of area and stiffen the column member. This combination of actions in conjunction with the application of pre-loading onto the top edge of the brackets reduces the effective height and slenderness ratio of the wind turbine tower.

Pre-loading in conjunction with the brackets 6 can reduce the effective height and slenderness ratio of the wind turbine tower significantly. By way of example only, for a I 30m overall height of tower for a 5MW turbine in the North Sea. If the brackets 6 are made 20m high, i.e. the top edge of the bracket, where the pre-loading is applied to the column member 2, is 20m above the level of the top of base member 3, then the effective height of the tower of I 30m could be reduced to 11 Urn, this would be an 15% reduction.

To assist with the installation of components 8, 10 and 11 and the lowering of column member 2 onto the base member 3 with bracket members 6 passing either side of post members 7, a temporary guide cap 28 with a tapering profile is placed on the top of the members 7.

When the column member 2 is positioned on the base member 3 to symmetrically accommodate in plan the raised plinth 21 on base member 3 there is a peripheral space 22 between the pliuth 21 and the inner face of the column member 2. This space is in-filled with concrete placed through the temporary delivery pipes 24, provided for this purpose, passing through the bottom section of the wall of the column member 2.

The delivery of concrete via delivery pipes 24 is continued until concrete of good quality arises out of the overflow holes 25, the plugs 27 having been removed, thus effectively filling the space 22 with solid concrete. The concrete is delivered by pumping from a ship on the surface canying a concrete mixing plant and the delivery pumps. The delivery pipes 24 and overflow holes 25 are arranged circumferentially around the column member 2 as shown in the following figs. 8A, 9, 10, 11 and 14A and 15A. The pipes 24 are temporary and are supported by removable brackets mounted to the outer face of the wall of the column member The cross 29 indicates the location and level at which a swaging tool can be introduced inside the vertical tubular post member 7. When the swaging tool is operated at this location coincident with annular collar member 8 it expands the vertical tubular post member 7 so that it comes to bear on the annular collar member 8 and causes the annular collar member 8 to stretch to accommodate the expansion of the tubular post member 7.

The annular collar member 8 becomes deformed by expansion and so grips the tubular post member 7 and forms the swaged connection between the two components after the swaging tool is removed. This connection rigidly connects the annular collar member 8 to the tubular post member 7.

In another embodiment of the present invention the bottom edge of bracket members 6 may be chamfered as indicated by dotted line W -W. If pre-loading of the connection is required, then the next stage, of pre-loading the connection of the column member 2 to the base member 3, can be carried out as follows.

This is the pie-loading method A already described in the introduction on pages 8, 9 and 10.

(method B is described for fig 7B below).

It can be seen in fig. 7A that when jacks 10 are operated, for example by the injection of pressurized fluid via pipes 26 opening the jacks, then the annular collar members 8 and the spreader plate members 11 are forced vertically apart creating a tension force in the tubular post member 7 and an equal compression force on bracket members 6 which is transferred onto column member 2 which is pressed down onto base member 3. The compression force also presses the bottom edge of the brackets 6 down onto the base 3.

The force generated by the jacks is measured and when the required force has been developed the jacks are made rigid or packing is installed within the gap between the spreader plate member 11 and the annular collar member 8 retaining the applied forces in the post member 7 and column member 2 after the jack 10 has been removed. In this way the column member and base member and the connections between these members are effectively pie-loaded and cannot move relatively to each other in a vertical direction.

The base plinth 21 with concrete filling 22 prevents the column member moving horizontally relatively to the base member. Therefore the swaged connection, in conjunction with the base plinth 21 with concrete filling of the space 22, rigidly connects the column member to the base member.

The plan section indicated by arrows DI-DI is shown on fig 9 and the plan section indicated by arrows E-E is shown on fig. 11.

Figure 7B shows the differences associated with embodiment B of post members 7 compared with embodiment A of post member 7 as shown in fig.7A. Fig.7B is drawn level with the corresponding part of fig.7A to enable the differences to be identified. The common components are 6,7, 8, 11 and 26 and the differing components are 10, 101 and 110.

If pre-loading of the connection is required, then the next stage of pre-loading the connection of the column member 2 to the base member 3, can be carried out as follows. This is the pre-loading method B, already described in the introduction on pages 8, 9 and 10.

It can be seen in fig.7B that when jacks 110 are operated then the flange member 101 and the annular collar members S are forced vertically apart creating a tension force in the tubular post member 7 and an equal compression force on annular collar members 8, on spreader member II and on bracket members 6 which is transferred onto column member 2 which is pressed down onto base member 3. The compression force also presses the bottom edge of the brackets 6 down onto the base 3.

The force generated by the jacks is measured and when the required force has been developed the swaged joint 29 is formed locking the annular collar 8 and post member 7 together and retaining the applied forces in the post member and column member after the jack 110 has been removed. In this way the column member and base member are effectively connected and cannot move relatively to each other in a vertical direction.

The force to be applied by the jacks will be need to be greater than the required pre-loading force because when the jacks are removed and the jacking force is transferred onto the swaged joint between members 7 and 8 there will be some slippage of the joint and a loss of some of the force. This loss has to be measured by testing trial installations and the necessary increased jacking force to be applied determined.

Figure 8A and 8B is a cross section elevation view as indicated by the arrows marked C2-C2 on flg.6A for a wind turbine assembly in which the column member is of tapering cross section of variable external overall diameter.

This is a detailed section through the vertical tubular post members 7 extending from the base member 3 and only differs from fig.7A and 7B above in that the column member 2 is of tapering cross section and therefore the wall of the column member is inclined as shown. All other details are the same as for fig.7A and 7B and the same notes and comments apply.

The plan section indicated by arrows D2-D2 is shown on fig. 10 and the plan section indicated by arrows E-E is shown on fig.l I. 3L-Figure SB shows the differences associated with embodiment B of post members 7 compared with embodiment A of post member 7 as shown in fig.8A. Fig.8B is drawn level with the corresponding part of fig. SA to enable the differences to be identified. The common components are 6,7,8, 11 and 26 and the differing components are 10, 101 and 110 Figure 9 is a cross section plan view as indicated by the arrows marked Dl-D1 on fig.7A and I 4A i.e. applicable to a parallel-sided column member.

This plan section shows the outer face of the curved wall of the column member 2 of the wind turbine assembly. Spreader plate members 11 are shown in plan and are sitting on top of the bracket members 6 shown dotted. Also shown is the possibility of a gap 28 between the edge of the spreader plate member 11 and the face of the wall of the column member 2.

Embodiment A of tubular post member 7 is shown in plan section with the annular collar member S around the outside perimeter of the post 7. The annular collar member 8 is sitting on top of the set ofjacks 10 sitting on top of the spreader plate member II.

For embodiment B of tubular post member 7 the jacks would be located near the top of the post 7 and so would not show in this plan section and the annular collar member 8 would sit directly on top of the spreader plate member 11.

The 5 examples of the layout of the connection details shown in fig. 9 show the spreader plate member 11 displaced in different directions relative to bracket members 6 and the face of the wall of the column member 2. These displacements are to accommodate post member 7 passing through the hole 23 in the spreader plate member when the post member 7 is not centrally located between the bracket members 6.

Also shown are possible errors affecting the location of the wall of column member 2 relative to the post members 7. These errors in the position and the exact size and shape of column member 2 affect the location of the outer face of the wall of column member 2 relative to the post members 7 and can be illustrated by possibly different locations of the centre point P1, P2 and P3 and small differences of the radii Ri, R2 and R3 which set out the position of the wall of the column member and also consequently the position of the bracket members 6 which are mounted to the wall. Because the spreader plate member I I is sized to be larger than the plan area of bracket members 6 the spreader plate member II, located to accommodate the displaced positions of members 2, 6 and 7 will still bear properly onto the full plate thickness of bracket members 6.

The pipes 24 are concrete delivery pipes arranged circumferentially around the column member 2 as shown. The pipes 24 are temporary. See also figs. 7A, 8A, 10, 11, 14A and iSA.

Additional plate members 40 may be added spanning between bracket members 6 to stiffen and stabilize the bracket members and support the spreader plates 11.

As stated, Fig 9 also provides plan section Dl -Dl for fig 14A. With reference to this, if additional piling as indicated by ref 52 on fig I 4A is installed then this would appear in the section, inside post member 7 on this plan fig 9.

Figure 10 is a cross section plan view similar to fig.9 as indicated by the arrows marked D2-D2 on fig. 8A and ISA, i.e. applicable to a column member of tapering cross section.

This is a detailed section plan through the vertical tubular post members 7 extending from the base member 3, the bracket members 6 and column member 2 and differs from fig. 9 above in that the column member 2 is of tapering cross section as shown. The repeated details are the same as for fig. 9 for both embodiments A and B of post member 7 and the same notes and comments apply. See also the notes re radii RI, R2 and R3 in the next paragraph.

In figs 7A, 8A and II, 14A and 15A following, the wall of the column members 2 is indicated by two lines indicating the thickness of the walls shown in these three sections through the walls.

In figs 9 and 10 the walls of the column members 2 is shown by a single line indicating only the outer face of the walls. This is intended to illustrate in these two plan sections the difference between the details associated with the parallel-sided column member shown in fig 9 and the tapering column member shown in fig. 10.

The two circumferential lines in fig 10 are at different levels, the two lines indicate upper and lower points on a sloping wall whereas the single circumferential line in fig. 9 indicates that the outer face of the wall is vertical.

In fig. 10 the radii R 1, R2 and R3 will change according to the level of the horizontal section shown in fig. 10 through the tapering column member. This is illustrated by the arrows RI U and R1L, R2U and R2L, R3U and R3L where RIU etc. represents a radius at an upper level and RI L etc. represents a radius at a lower level of the tapering column member.

In fig. 10 the bracket members 6 are drawn with solid lines extending beyond the edge of the spreader members 11. This extension of bracket plates 6 is to accommodate the sloping face of the wall of the column member 2 to which the bracket members 6 are mounted. This results in the gap 28 shown in fig. 10 being wider than the gap 28 shown in fig. 9. However this would not be the case if the spreader plates 11 were made larger to extend closer to the sloping face of the wall of the column member 2. This may be required for the transfer of load from spreader member 11 to column member 2.

As stated, Fig 10 also provides plan section D2 -D2 for fig 1 5A. With reference to this, if additional piling as indicated by ref. 62 on fig ISA is installed then this would appear in the section, inside post member 7 on this plan fig. 10.

Figure 11 is a cross section plan view as indicated by the arrows marked F-F on figs.7A, 8A, l4A and iSA This plan section passes through the bottom part of the curved wall of the colunm member 2 of the wind turbine assembly. Part of the floor slab 46 of the column member 2 is shown extending over the raised base plinth 21, which extends above the base member shown by the dot 3, which indicates the top surface of base member 3 at a lower level. The bottom of the wall of the column member 2 sits on the top surface 3 of the base member.

There is a continuous curved space 22 between the raised plinth 21 and the inside face of the curved wall of column member 2 extending around the whole perimeter of the raised plinth under the floor slab 46 of the column member. This space is in-filled with concrete delivered through the temporary delivery pipes 24, provided for this purpose, passing through the bottom section of the wall of the column member 2.

The delivery of concrete via delivery pipes 24 is continued until concrete of good quality arises out of the overflow holes 25, the plugs 27 (see figs 7A, 8A, 14A and ISA) having been removed, thus effectively filling the space 22 with solid concrete. Overflow holes 25 in the segment of the floor slab 46 are shown frill line. Where the floor slab is not included in the plan the holes 25 are shown above by a dotted line. Similarly delivery pipes 24 under the segment of floor slab 46 are shown dotted line, and are shown solid line where visible in an adjoining part of space 22.

The concrete is delivered by pumping from a ship on the surface carrying a concrete mixing plant and the delivery pumps. The delivery pipes 24 and overflow holes 25 are arranged circumferentially around the column member 2 as also shown in the figs. 7A, SA, 9, 10 and I 4A and I 5A. The pipes 24 are temporary and are supported by removable brackets mounted to the outer face of the wall of the column member 2 Bracket members 6 are shown in plan section mounted to the outside face of the column member 2 and the vertical tubular post members 7 are shown in plan section located between the bracket members 6. Additional plate members 40 may be added spanning between bracket members 6 to stiffen and stabilize the bracket members.

Embodiment A and B of tubular post member 7 appear the same, as a circle in plan for all four sections marked E-E on figs.7A, SA, l4A and 15A. However, for the sections applying to figs 14A and ISA, if additional piling is provided within post members 7 then it will appear on fig 11, three examples including additional piles 52 or 62 are indicated. The other two examples of post member 7 without internal additional piling apply to figs 7A and 8A Figure 12A is a plan section view generally similar to fig.5A, in which a wind turbine column member with parallel sides is mounted to an undefined wind turbine base member 3.

But in fig 12A the base member 3 comprises a defined piled foundation for a wind turbine assembly. Ten swaged connections 5 are shown.

The layout of the column member 2 and the swaged connections 5 is not symmetrically related to the layout of the piles 51 comprising the piled foundation although there could be advantages if they were symmetrically related and this could be achieved.

In this plan, the perimeter 50 of the base member 3 is defined and the locations of piles 51 comprising the wind turbine assembly foundation are shown. The base member 3 comprises a pile cap 50 forming the piled foundation for the wind turbine assembly.

Piles 51 are driven through pile sleeves 64 in the base member and the pile sleeves 64 are anchored into the base member. An effective method for connecting the piles 51 to the base member 3 would be to swage the piles 51 to the pile sleeves 64 in a similar way as for the swaged connections between the annular collar members 8 and the post members 7 as described in previous figures. See also figs.16 and 17.

The strength of the pile sleeves 64 and the anchorage of the pile sleeves within the base member is sufficient to transfer the design loads from the base member into the pile sleeves.

If required, ten additional piles 52 can be added to the foundation by installing one pile through each of the vertical tubular post members 7 of the swaged connections. These additional piles 52 are connected to the base member 3 by a swaged joint between the piles 52 and the tubular post members 7, which are anchored into the base member. Post members 7 will then be fulfilling a second function as a pile sleeve.

There is a raised plinth extending from the base member into the bottom part of the column member under the floor slab of the column member. The location of this plinth is indicated by the dotted line circle marked 55 Section Fl-Fl is shown in fig.14A.

Figure 12B shows an enlargement of a segment of fig.12A with the same centre point 206.

The same notes apply as for fig 58 above with regards to man access for maintenance enabled by the installation of a temporary cofferdam 200. In addition, fig.12B relates to a piled base and if additional piles are installed using the post members 7 as pile sleeves then the additional piles 52 will appear in this section plan within post members 7 as indicated.

Figure 1 3A is a plan section view generally similar to fig.6A, in which a wind turbine column member with a tapering cross section is mounted to an undefined wind turbine base member 3. But in fig!3A the base member 3 comprises a defined piled foundation for a wind turbine assembly. Ten swaged connections 5 are shown.

The layout of the column member 2 and the swaged connections 5 is symmetrically related to the layout of the piles 61 within the base member 3 comprising the piled foundation and shares a common grid. This symmetrical layout, sharing a common grid, optimizes the performance of all the piles 61 and 62 (see below) in the pile group.

However, the symmetry may create problems for accommodating the installation barge used to deliver and mount the column member to the base member. If this is the case then a different non-symmetrical arrangement will be required.

In this plan the perimeter 60 of the base member 3 is defined and the locations of piles 61 comprising the wind turbine assembly foundation are shown. The base member comprises a pile cap 60 forming the piled foundation for the wind turbine assembly.

Piles 61 are driven through pile sleeves 64 in the base member and the pile sleeves 64 are anchored into the base member. An effective method for connecting the piles 51 to the base member 3 would be to swage the piles 51 to the pile sleeves 64 in a similar way as for the swaged connections between the annular collar members S and the post members 7 as described in previous figures. See also figs. 16 and 17.

If required, twelve additional piles 62 can be added to the foundation by installing one pile through each of the vertical tubular post members 7 of the swaged connections. These additional piles 62 are connected to the base member 3 by a swaged joint between the piles 62 and the tubular post members 7, which is anchored into the base member, Post members 7 will then be fulfilling a second flrnction as a pile sleeve.

There is a raised plinth extending from the base member into the bottom part of the column member under the floor slab of the column member. The location of this plinth is indicated by the dotted line circle marked 65.

Section F2 -F2 is shown in fig. I 5A By way of example only, the pile caps illustrated in figs.l2A and 13A could be approximately 20m by 20m in plan size. The thickness of the pile cap would be of the order of 3m to 4m thick, of reinforced concrete construction. This size of pile cap could accommodate approximately 40 piles and would be suitable for a 5 MW offshore wind turbine in the North Sea. The column member diameters and connection details as drawn illustrate at the same scale as the base member perimeter plans the column sizes that would be required for 5MW wind turbines, by way of example only, between Sm and 1 2m in diameter. As can be seen in figs.5A and oA, and figs.12A and 13A, as the size of column member 2 increases more connections 5 can be accommodated around the perimeter of the column member.

In this way the present invention will be applicable to both today's offshore wind turbines and future offshore wind turbines of increasing size requiring larger column members and base members and stronger connections for mounting the wind turbine towers to the foundations.

By way of a further example only, a pile cap similar to the pile caps illustrated in figs.12A and 1 3A could be approximately 27m by 27m in plan size by 4m thick, of reinforced concrete construction. This larger size pile cap could accommodate approximately 80 piles and would be suitable for a 10 MW offshore wind turbine in the North Sea. The column member would be approximately 13m in diameter and this size of column member could accommodate 16 or more connections in accordance with the present invention using steel tubes 914mm diameter for the post members extending from and anchored into the base member.

Figure 13B shows an enlargement of a segment of fig.13A with the same centre point 207.

The same notes apply as for fig 58 above with regards to man access for maintenance enabled by the installation of a temporary cofferdam 200. In addition, fig.1 3B relates to a 14-s piled base and if additional piles are installed using the post members 7 as pile sleeves then the additional piles 62 will appear in this section plan within post members 7 as indicated.

Both the following figs l4A and I 5A show in section the possible location of piles generally located within a base member comprising a piled foundation as described in the present invention. These cross sections also show the possibility of inserting piles through the vertical tubular post members 7 comprising the swaged connection described in the present invention. This facility, if used, increases the number of piles that can be accommodated within a base member of a given size comprising a wind turbine foundation.

Figure 1 4A is a cross section elevation view as indicated by the arrows marked Fl-Fl on fig. I 2A for a parallel-sided wind turbine column member. The details on fig. I 4A are generally the same as on fig 7A except that fig.14A relates specifically to a piled foundation for a wind turbine assembly. It can be seen that the embodiment A of the vertical tubular post member 7 extends to the lower surface of the base member and is open ended to provide the facility of post member 7 also acting as a pile sleeve if required to accommodate additional piling 52.

Also shown is one of the pile sleeves 64 required for a piled foundation comprising the base member with piles 51 shown inside the sleeve, as shown in fig 12A.

For a typical 5MW offshore wind turbine assembly comprising a piled foundation comprising 918mm diameter steel tubes with a 30mm. wall thickness for the piles there is a requirement for approximately 40 piles if the wind turbine is founded at a location where the seabed comprises adequately strong ground. Ten of these piles could be installed within the swaged joint vertical tubular post members 7 plus another 28 within the pile sleeves 64 (see fig.12A) making a total of 38, which is approximately 40 as explained. In fig.14A the pile sleeves 64 are shown with shear stud type anchorages 63 cast into the concrete forming the base member 3 as an alternative to the fabricated type of anchor 20, also shown on post member 7 acting as a pile sleeve.

If additional piles 52 are installed using the lower part of post members 7 acting as a pile sleeve then the pile can be cormected to the pile sleeve by means of a swaged joint at the location indicated by cross Y. This swaged joint will be similar to the swaged joint between the annular collar member 8 and post member 7 at the location indicated by cross X (29 on L2 figs. 7A and 8A). Swaged joint X is formed before the pile 52 is installed. Similar swaged joints arc used to connect piles 5 to sleeves 64 as indicated by cross Z. The levels of swage joints Y and Z are indicative only and may vary.

Also shown in fig. 14A are typical locations for the concrete delivery pipes 24 and the overflow holes 25 and removable plugs 27 described previously.

Section Dl -Dl is shown on fig. 9 and section E -B is shown on fig. 11.

In another embodiment of ihe present invention the bottom edge of bracket members 6 may be chamfered as indicated by dotted line W -W. If pre-loading method A, already described in the introduction on pages 8, 9 and 10, is required then the detailed notes for fig. 7A apply to fig. 14k Figure 1 4B shows the differences associated with embodiment B of post members 7 compared with embodiment A of post member 7 as shown in figl4A. Fig 14B is drawn level with the corresponding part of fig 1 4A to enable the differences to be identified. The common components are 6,7, 8, 11 and 26 and the differing components are 10, 101 and 110.

If pre-loading method B, already described in the introduction on pages 8, 9 and LU, is required then the notes for fig. 7B apply to fig. 14B.

Figure 1 5A is a cross section elevation view as indicated by the arrows marked F2-F2 on fig. I 3A for a wind turbine column member with a tapering cross section and therefore the wall of the column member is inclined as shown.

The details on fig. ISA are the same as on fig 14A but applied to a wind turbine column member with a tapering cross section and relate to the plan on fig. I 3A. The notes and comments will be the same, however the total number of piles 61 and 62 will be 28 plus 12, equal to 40 number piles suitable for a 5MW offshore wind turbine assembly.

If additional piles 62 are installed using the lower part of post members 7 acting as a pile sleeve then the pile can be connected to the pile sleeve by means of a swaged joint at the location indicated by cross Y. This swaged joint will be similar to the swaged joint between the annular collar member 8 and post member 7 at the location indicated by cross X (29 on figs. 7A and 8A). Swaged joint X is formed before the pile 62 is installed. Similar swaged joints are used to connect piles 61 to sleeves 64 as indicated by cross Z. The levels of swage joints Y and Z are indicative only and may vary.

Section D2 -D2 is shown on fig. 10 and section E -E is shown on fig. 11.

In another embodiment of the present invention the bottom edge of bracket members 6 may be chamfered as indicated by dotted line W -W. If pre-loading method A, already described in the introduction on pages 8, 9 and 10, is required then the detailed notes for fig. 7A apply to fig. I SA.

Fig. 1 5B shows the differences associated with embodiment B of post members 7 compared with embodiment A of post member 7 as shown in fig.1SA. Fig.1SB is drawn level with the corresponding part of fig.! 5A to enable the differences to be identified. The common components are 6,7, 8, 11 and 26 and the differing components are 10, 101 and 110.

If pre-loading method B, already described in the introduction on pages 8, 9 and 10, is required then the notes for fig.7B apply to fig.15B.

Figure 16 shows details of a swaged joint between two steel tubes, a shorter length of tube 72 fitting around the outside of a longer tube 71. The solid lines defining tubes 71 and 72 show the deformed shape of the tubes after the swaging procedure. The original shape of the tubes, one inside the other, is shown by the dotted lines 73 and 74.

The curvature of the swaged tubes as drawn is exaggerated in the figs.16 and 17 to illustrate the swaging process, in reality the distortion of the tubes will be very much less and would not show if drawn to the scale of the figs. 16 and 17. 4L

The swaged joint is formed by inserting the swaging tool 70 into the inner tube 71 at the required location of the swaged joint. The swaging tool is operated and it expands the inner steel tube 71 so that it comes to bear on the outer tube 72 and causes the outer tube to stretch to accommodate the expansion of the inner tube. The outer tube becomes deformed by this expansion and so grips the inner tube, which is also defonned by the swaging process and the permanent distortion of the two tubes forms the rigid swaged connection between the two tubes.

The diameters of the tubes for a given joint are designed to ensure that the appropriate distortion of both tubes occurs during the swaging process to form a strong rigid joint of proven load transfer capability. The swaging procedure illustrated here is prior art and is well established in the offshore oil and gas construction industry.

This method would be suitable for forming the rigid joint required between the tubular post members 7 and the annular collar member S for the embodiment of the present invention described in the previous figs I to 15.

On figs. 7A and 7B, and 8A and 8B, the location of this swaged joint is shown by cross 29, and on figs.14A and 14B, and iSA and 15B, the location of this swaged joint is shown by cross X. The direct load capability of the swaged joint, i.e in the case of the present invention the vertical load capacity, can be increased by using two or more swages adjacent to each other to form multiple swages between the tubes.

The moment transfer capability of the swaged joints can be increased by using two or more swages adjacent to each other to form a couple providing moment capacity.

As already explained, swaged joints are formed by the insertion and operation of a swaging tool inside a pair of concentric steel tubes. Operation of the swaging tool distorts the steel tubes and to achieve the optimum strength of the joint the length of the steel tubes should extend beyond the length over which the tubes are distorted. The length of the inner tube beyond the distorted section in figi 6 is indicated by the dimension L2 and the length of the outer tube beyond the distorted section is indicated by the dimension Li. The lengths Li and L2 as shown are indicative only and the actual lengths that will be required in an application of the present invention would be assessed and defined in accordance with the specific joint requirements for that application.

This aspect of the swaged joint applies to the swaged joint details X, Y, Z and 29 shown in figs 7A, 8A, l4A and I 5A The lengths and termination of steel tube shown in these figures are indicative only and the details of the actual swaged joints incorporated in various embodiments of the present invention will take into account these considerations.

Furthermore the length of the swaged joint, i.e the length of steel tube modified by the swaging tool, and the number of swages installed, has to be determined for each application of the swaged joint incorporated in embodiments of the present invention and most likely will be different to the lengths shown indicatively within the figures included in this

specification.

Figure 17 illustrates a swaged joint similar to the swaged joint shown in fig 6 but applied to the general piling for a piled wind turbine foundation as described.

Referring to figs. 12A and 12B, 13A and 13B, 14A and 15A. A swaged joint detail similar to fig. 16 can be applied to piles 51 and 61 which are installed inside the pile sleeves 64 shown in figs.14A and ISA as indicated by cross Z. Pile sleeves 64 include shear stud anchorages 63 to anchor the sleeve into the cast concrete forming the base member 3.

Also the additional piles 52 and 62, if required, can be swaged within the post members 7 using the same procedure as described in fig. 16 to connect these piles to the post members 7 acting as a pile sleeve, as shown in figs 14A and 15A as indicated by cross Y. If required, any gap that may remain between the piles and the pile sleeves at levels above and below the swaged joints can be filled by underwater pressure grouting techniques or other appropriate techniques after the swaging has been carried out. The filling of such gaps will increase the rigidity of the joint between the pile and the pile sleeve and increase the capacity of the joint to transfer moments applied to the joint due to lateral forces on the base member. The gaps may be present as a result of providing sufficient clearances between the piles and the pile sleeves to facilitate the piles passing through the sleeves during driving.

For the notes regarding additional tube lengths indicated by the dimensions LI and L2 and the importance of these extra lengths of steel tube, refer to these aspects as noted on fig 16.

There is a further advantageous aspect of the swaged joints incorporated in the embodiments of the present invention in the case of piled foundations as described in this specification and illustrated in the figures. This aspect relates to the possibility of increasing the load carrying capacity of the foundation by installing additional piles at some time after the original piling for the original foundation loads. This facility supports the option of upgrading the whole wind turbine assembly to provide greater generating power if required while still using all the existing structure.

Additional piles could be installed by driving them through the open tubes forming the original piles. The original piles are driven through the pile sleeves and also, if required, through the connecting posts acting also as pile sleeves. In the same way as the original piling is connected to the pile sleeves by swaging the later additional piling can be connected to the original piling by swaging. An example of this is shown in figure 17 where additional pile 81 is shown inside original piles 51 or 61.

The additional piles 81 are connected to the original piles 51 or 61 by a ifirther swaged joint 82 adjacent to the top end of the original pile 51 or 61. In anticipation of installing additional piles at some time in the future the tops of the original piling would have to extend above the top of the pile sleeves by a distance greater than L2 to include the additional length required to accommodate the later formation of the swaged joint 82.

The diameter of the additional piles 81 has to correspond to the internal diameter of the original piling in accordance with the tolerances required for forming the swaged joint 82.

If additional piling is to be installed, then at the time of installation, to enable the additional piling to be installed through the frill length of the original piles, it may be necessary to bore out material present inside the original piling. This is foundation material from below the sea bed, that has driven up into the original pile tubes as a result of the original pile driving.

The additional piling can serve several functions. It can extend beyond the end of the original piling and so increase the vertical load carrying capacity. The additional piling can also reinforce the original piling by increasing the bending resistance and resistance to horizontal shear due to the combined action of two tubes, one inside the other. The combined tubes will be stiffer than the original piles and so could reduce horizontal deflection of the foundation due to horizontal loads.

The methods described here for the present invention can be used to enable the delivery of wind turbine assemblies and erecting columns comprising wind turbine assemblies in which the columns are single element columns or consist of more than one element and may be erected using cranes or telescopic methods using jacks or by floatation methods or any combination of these methods.

Base members may be delivered and installed using cranes, barges or floatation methods or any combination of these methods.

The invention provides any suitable combination of features of the apparatus, method steps and operation of any of the embodiments described.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features herein before referred to andlor shown in the drawings whether or not particular emphasis has been placed thereon. (-s-s

Claims

<claim-text>CLAIMS1 A connection formed under water between a wind turbine column member comprising a wind turbine tower and a wind turbine base member comprising a wind turbine foundation.</claim-text> <claim-text>2 A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claim including joints that are formed by swaging, crimping, pegging, wedging, or any other procedure.</claim-text> <claim-text>3 A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims including bracket extension members mounted to the column member.</claim-text> <claim-text>4 A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims including connecting extension members mounted to the wind turbine base member.</claim-text> <claim-text>A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims in which bracket extension members mounted to the column member pass alongside or around connecting extension members mounted to the wind turbine base member.</claim-text> <claim-text>6 A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims including spreader members bearing on the bracket extension members mounted to the column member.</claim-text> <claim-text>7 A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims, the connecting extension members mounted to the wind turbine base member passing through or past and adjacent to the spreader members.</claim-text> <claim-text>8 A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims including collar members or other equivalent enlarging members passing around or adjacent to or comprising the connecting extension members mounted to the wind turbine base member and bearing on the spreader members.</claim-text> <claim-text>9 A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims including extendable jacking members, to enable the pre-loading of the connection prior to the application of service loads, fitting around or adjacent to the connecting extension members mounted to the wind turbine base member and bearing on the spreader members or on the collar members or equivalent enlarging members.</claim-text> <claim-text>A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims including a raised plinth member or a rebate in the top of the base member or a wall member extending from the base member into or around the bottom of the column member and including associated solid filling material placed in a space or spaces between the raised plinth, rebate or wall member and the wall of the column member which prevents any horizontal movement of the column member relative to the base member occurring.</claim-text> <claim-text>11 A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims in which the members comprising the connection described are of sufficient strength to form a connection of the required strength.</claim-text> <claim-text>12 A connection formed under water between a wind turbine column member and a wind turbine base member including bracket extension members mounted to the column member in accordance with the claim 3, the bracket extension members also acting as stiffeners that increase the stifthess of the column member and reduce the horizontal deflections of the tower due to the action of horizontal forces on the tower comprising the column member.</claim-text> <claim-text>13 A connection formed under water between a wind turbine column member and a wind turbine base member including bracket extension members mounted to the column member 5o in accordance with the claim 3 and including extendable jacking members to enable the pre-loading of the bracket members of the connection in accordance with claim 9, the combined effect of both members being to reduce the effective height of the wind turbine tower.</claim-text> <claim-text>14 A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims including a temporary cofferdam with a roof over mounted to the base member extending above sea level to enable dry safe man access for maintenance of the connections and the wind turbine tower.</claim-text> <claim-text>A connection formed under water between a wind turbine column member and a wind turbine base member in accordance with the previous claims including additional piles installed through the open tubes forming the original piling at a time after the installation of the original piling in order to increase the load, shear and bending moment carrying capacity of the wind turbine foundation.</claim-text> <claim-text>16 A connection formed under water between a wind turbine column member and a wind turbine base member including bracket extension members mounted to the column member in accordance with previous claim 3, the bracket extension members being positioned so that there is sufficient space for safe man access between the bracket extension members and the connecting extension members in accordance with previous claim 4 mounted to the wind turbine base member and the column member to enable maintenance of these members.</claim-text> <claim-text>17 A method whereby a swaging tool, a crimping tool, pegs or wedges or other devices are applied or installed to the members forming the connection in accordance with the previous claims including to connecting extension members mounted to the wind turbine base member and to collar members or equivalent enlarging members located around or adjacent to the connecting extension members mounted to the wind turbine base member.</claim-text> <claim-text>1 8 A step in accordance with the previous claim whereby a swaging tool or a crimping tool is operated or pegs or wedges or other devices are installed to form joints that rigidly join together the collar members or equivalent enlarging members and the connecting extension members mounted to the wind turbine base member. 5-I</claim-text> <claim-text>19 A step in accordance with the previous claims whereby an extendable jacking member is operated to generate tension force within the connecting extension members mounted to the base member and applying compression force onto the bracket extension members mounted to the column member, the force in the jacks being measured and adjusted to a required size of force to provide required pre-loading of the connections between the column member and the base member.</claim-text> <claim-text>A step in accordance with the previous claims whereby when the compression force onto the bracket extension members mounted to the column members and the tension force generated in the connecting extension members mounted to the wind turbine base member are of the required size of forces then the extendable jacking member is made irreversibly solid so that it cannot be ftirther extended or contracted or removed or packing is inserted to maintain these forces and the jacks are removed.</claim-text> <claim-text>21 A step in accordance with the previous claims whereby the spaces between the raised plinth member mounted on the base member or the rebate in the top surface of the base member or the wall member mounted on the base member and the inside or outside face of the wall of the column member are filled with solid material to prevent movement occurring between the wall of the column member and the raised plinth or wall and the base member 22 A step in accordance with the previous claims whereby the column member is rigidly connected lii the base member and cannot be displaced in any direction relative to the base member and the strength of the connection members is sufficient to transfer all of the moments and forces applied to the connection.23 A step in accordance with the previous claims whereby the base member comprising a foundation rigidly connected to the ground on which the base member is supported cannot be displaced in any direction relative to the ground on which the base member is supported and to which the foundation is connected.24 A step in accordance with the previous claims whereby the column member rigidly connected to the base member cannot be displaced in any direction relative to the ground on which the foundation including the base member is placed and by which the base member is supported.A step in accordance with all the previous claims whereby the location relative to each other of the members forming the connections is adjusted to accommodate the disposition between the connecting extension members mounted to the base member and the bracket extension members mounted to the column members and passing alongside or around the connecting extension members mounted to the base member and to accommodate dimensional errors within the component members forming the connections.26 A step in accordance with all the previous claims whereby a pre-loading jacking force is imposed upon the top edge of the bracket members which reduces the effective height and slenderness ratio of the wind turbine tower.27 A step in accordance with all the previous claims whereby a temporary cofferdam with a roof over is mounted at intervals to the base member, the cofferdam extending above sea level and made dry by pumping to enable safe man access for maintenance of the connections and the wind turbine tower.28 A step in accordance with all the previous claims whereby additional piles are installed by being setup and then driven through the open tubes forming the original piling and then being connected to the original piles using swaged joints all carried out at a time after the installation of the original piling in order to increase the load, shear and bending moment carrying capacity of the original wind turbine foundation.29 A step in accordance with all the previous claims in order to complete the construction of a wind turbine assembly at the final location of the wind turbine assembly.A step in accordance with claim 29 to generate electricity using a wind turbine assembly.31 A step in accordance with claim 30 to supply electricity to parties acquiring electricity.</claim-text>