METHOD FOR PRODUCING A CONNECTION BETWEEN TWO PIPE SEGMENTS OF A TOWER-LIKE STRUCTURE

Description

[0001] The subject matter relates to a method for producing a connection between two pipe segments of a tower-like structure. In particular, the method relates to the connection between two pipe segments of an offshore structure, a wind turbine, or an offshore wind turbine.

[0002] Document EP 3 255 210 A2 is part of the prior art and is considered useful for understanding the invention.

[0003] Tower-like structures, especially offshore structures, and preferably offshore wind turbines, are generally founded in the ground, particularly the seabed. This foundation is achieved using so-called monopiles, tripiles, or pile-anchored jackets or tripods. These are pipes, especially steel pipes, that are driven into the seabed using suitable hammers. A transition piece connects the top of these driven pipe segments to the rest of the structure. The transition piece is mechanically connected to the foundation pile. In this context, the transition piece refers to any pipe-like element between the pile and the tower, with or without internal components.Such a connection can be a flange connection, a so-called grout connection with a potting compound, or a sliding connection of two nested pipe segments, a so-called slip joint.

[0004] In a grout joint, the annular space between the nested pipe segments is filled with grout, particularly cement grout, during installation. The grout hardens, creating a force-fit and form-fit connection between the pipe segments. A grout joint typically has a minimum expected service life of 15 to 25 years.

[0005] Besides the grout joint, another well-known connection is the slip joint. Here, the pipe segments are pushed into one another and, unlike with the grout joint, lie directly against each other when inserted. For this to work, the upper tower segment can be slipped onto the lower tower segment, or the upper tower segment can be inserted into the lower tower segment. In conventional slip joint connections, the upper pipe segment tapers on its outer wall towards a lower end, which is inserted into the lower tower segment. The lower tower segment widens on its inner wall towards an upper end, into which the upper pipe segment is inserted. These tapers can correspond to each other, be complementary, and, in particular, be conical. If the upper segment is slipped onto the lower segment rather than inserted, the tapers run in the opposite direction.

[0006] A relatively new joining technology is the so-called double slip joint. In this technology, the two pipe segments to be inserted into one another are not brought into direct contact along their entire interlocking surface. Instead, joining elements are provided at intervals along the longitudinal direction of the pipe segments. These joining elements run in a plane perpendicular to the longitudinal axis of the pipe segments and are arranged at least partially, preferably completely, around an inner and / or outer wall of a pipe segment. The joining elements have corresponding and complementary surfaces that lie against each other when joined. The joining surfaces of two pipe segments face each other. The joining elements can taper conically towards the respective end face where the pipe segments are joined.Double slip joint connections are considerably more cost-effective than full-surface slip joints, since only the joining elements and their joining surfaces need to have sufficiently high dimensional accuracy, while the pipe segments themselves only have lower requirements for dimensional accuracy in the area of ​​their end face.

[0007] Since joints, especially in offshore structures, must remain reliably stable for at least a decade, preferably more than a decade, and particularly two decades or longer, there is a risk that new technologies, once deployed in the field, will not withstand continuous stress. This is problematic when large numbers have already been deployed and need to be retrofitted. In offshore structures, this is virtually impossible or involves such high costs that they are comparable to a new installation. This must be prevented. Therefore, there are currently concerns about installing double slip joints in large numbers without years of testing.

[0008] The subject matter was therefore based on the task of providing a method that enables the use of double slip joints with a minimized risk of failure.

[0009] This problem is solved by a method according to claim 1.

[0010] In this process, two pipe segments of a tower-like structure are inserted into one another. The pipe segments can be made of steel and / or reinforced concrete. Any combination of materials is conceivable.

[0011] The lower pipe segment has an upper end face, and the upper pipe segment has a lower end face. "Upper" and "lower" refer to the installed state of the pipe segments. Preferably, the lower pipe segment is anchored in the ground, more preferably the seabed, when installed. The pipe segments are pushed together at their facing end faces, the lower and the upper.

[0012] Joining elements can be arranged on the facing outer surfaces of the pipe segments when they are inserted. It is possible that both pipe segments have corresponding joining elements, or that one pipe segment has a joining element and the outer surface of the other pipe segment is formed in a corresponding, complementary manner to the joining element. Such a corresponding outer surface can also be understood as a joining element in the broadest sense.

[0013] The joining elements have joining surfaces where direct contact is formed between the pipe segments, or rather their respective joining elements, when installed. The joining elements are, in particular, at least partially circumferential projections on the inner or outer surface of a respective pipe segment.

[0014] If the upper pipe segment is inserted into the lower pipe segment, a joining element is arranged on the inner surface of the lower pipe segment and on the outer surface of the upper pipe segment. If the upper pipe segment is placed over the lower pipe segment, a joining element is arranged on the outer surface of the lower pipe segment and on the inner surface of the upper pipe segment.

[0015] The corresponding joining elements are each arranged at a distance in the longitudinal direction of the pipe segment from an end face edge on the lateral surface of the pipe segment.

[0016] For a double slip joint, at least two joining elements are arranged on the outer surfaces of the pipe segments. These at least two joining elements are spaced apart from each other along the longitudinal axis of the respective pipe segments.

[0017] The clear opening, i.e., the minimum free inner diameter, of a joining element located closer to the end face of a receiving pipe segment is generally larger than the clear opening of the joining element located further away from the end face of the receiving pipe segment. This ensures that the pipe segment to be inserted, with its joining element located closer to the end face, can be pushed into the receiving pipe segment and past the joining element located closer to the end face, all the way to the joining element located further away from the end face.

[0018] The pipe segments, which are inserted into one another, are mechanically coupled via the joining elements, or rather the corresponding joining surfaces of the joining elements. The pipe segments are aligned with each other, particularly by means of conical joining surfaces.

[0019] The joining of two pipe segments of a tower-like structure described above results in a so-called double slip joint, in which at least two preferably annular joining elements are in direct contact with each other on the corresponding outer surfaces of the respective pipe segments, spaced apart from each other longitudinally. The corresponding joining surfaces of the respective joining elements are in contact with each other in the installed state. The joining surfaces align the pipe segments relative to each other and mechanically couple them together. Such a connection is already known.

[0020] The joining elements extend radially along the pipe segment. A joining element on an outer surface extends radially outwards, while a joining element on an inner surface extends radially inwards. When the joining surfaces of the joining elements of two pipe segments are in contact, an annular gap forms between the pipe segments, particularly in the longitudinal direction between the joining elements. This annular gap is used to subsequently fill it, as will be described below.

[0021] To enable the widespread use of this double slip joint in tower-like structures, it is essential that it remains stable over its required service life. This has not yet been adequately tested, leading to concerns that double slip joints can withstand the mechanical stresses encountered in the field. This is particularly relevant for offshore structures, especially wind turbines.

[0022] Wind power plants can be wind turbines, substations, transformer stations, or similar structures. Tower-like structures can also be drilling platforms (oil, gas), mountings for photovoltaic systems, or similar.

[0023] It is proposed that at least one mechanical parameter of the mechanical coupling between the pipe segments be detected by at least one sensor on at least one pipe segment. A single parameter can be detected by one sensor, or multiple parameters can be detected by one or more sensors. A sensor can be a measuring instrument. In particular, a sensor can be a strain gauge or an accelerometer. Other relevant sensors include pressure transducers for detecting radial pressures and stresses, inductive or electromagnetic sensors, or acoustic sensors, which provide information about possible cracking in the material of the joining surfaces.

[0024] These sensors are preferably arranged directly on the pipe segments and / or directly on the joining elements. Mechanical parameters, as described below, can be measured using these sensors.

[0025] A tower-like structure is designed and dimensioned for specific mechanical loads. In particular, limit values ​​are defined for certain mechanical parameters, below which the structure is considered stable. If such limit values ​​are exceeded or fallen below, the mechanical stability of the structure may be compromised. This depends especially on the stress-strain behavior of the components, their vibration behavior, their movement relative to each other, and similar factors. If a mechanical parameter deviates from its target range, the entire structure is at risk. Since, as already mentioned, double slip joints have not yet been used extensively, particularly in offshore applications, it is unknown whether they can withstand the considerable mechanical loads.Using this measuring device, it is possible to check whether the mechanical parameters of the pipe segments and / or joining elements are within the target values. The mechanical parameters are monitored after initial installation and commissioning of the structure.

[0026] Additionally or alternatively, the sensors detect whether material defects, cracking, corrosion, or other changes are present that affect or endanger the load-bearing capacity and mechanical properties of the base material and / or sometimes lead to sudden changes or increase the probability of brittle failure. Ultimately, these changes also compromise the mechanical stability of the structure.

[0027] If, after initial installation and commissioning of the structure, the recorded mechanical parameters indicate that the structure's mechanical stability may be compromised, a warning signal can be issued. This warning signal triggers a process culminating in the filling of the annular gap between the pipe segments with grout. Based on the warning signal, a construction crew can be dispatched to fill the annular gap at the appropriate time. This ensures that the connection between the pipe segments, initially designed as a double slip joint (DSJ), remains permanently stable as a grout joint for the remaining service life of the structure, thanks to the grout. The stability can also be achieved, increased, or extended through the combined load-bearing capacity of the DSJ and the grout joint.

[0028] When the following description refers to a mechanical parameter being measured on a pipe segment, it always implies that this parameter can also be measured on a joining element. A mechanical parameter can be measured on a pipe segment, on a joining element, or on both. This also includes mechanical parameters that can be derived by measuring acoustic or electromagnetic signals.

[0029] A joining element can be an integral part of a pipe segment or be arranged as a separate component on the pipe segment, in particular on its inner wall (inner surface) or outer wall (outer surface). In particular, the joining element can be welded to the material of the pipe segment.

[0030] One possible parameter is the strain of the pipe segment. The elastic and / or plastic strain of the pipe segment can be measured using a strain gauge.

[0031] Another mechanical parameter can be the compression of the pipe segment. The elastic and / or plastic compression of the pipe segment can be measured using a strain gauge.

[0032] Another mechanical parameter can be the vibration of the pipe segment. This vibration can be measured using either a strain gauge or an accelerometer.

[0033] The acceleration of the pipe segment can also be a mechanical parameter. This acceleration can be measured, in particular, using an accelerometer.

[0034] Relative movements of the pipe segments relative to each other can also be recorded as mechanical parameters. In this case, values ​​from two sensors, each positioned on one of the pipe segments, can be compared to each other, thus enabling the detection of relative movement between the segments.

[0035] A natural frequency can also be a mechanical parameter. A mechanical structure can exhibit a specific response to dynamic mechanical stress. This can be understood, for example, as a step response or shock response. Such a response can be evaluated in the frequency spectrum. In particular, a change in the natural frequency can be detected. A change in the natural frequency indicates a mechanical change in the structure. This also includes high-frequency natural vibrations, which can provide information about cracking.

[0036] In particular, the 1st - 5th natural frequencies must not deviate from the target value by more than 5%, preferably by less than 2%.

[0037] Another mechanical parameter can be the stress / strain value of the pipe segment. This can be measured, for example, according to VDI 4551. A further parameter can be the cracking, in the form of length and / or number of defects.

[0038] For each parameter, a target value or a target value range can be specified. Such a target value can be calculated in advance using simulations. This makes it possible to calculate which mechanical parameters will assume which values ​​under which loads. It is also possible to determine at what deviation a parameter indicates an impending or actual defect in the structure. These simulations can be performed using computer-aided methods before the structure is installed.

[0039] Once target values ​​or target value ranges have been determined, these can be used to compare them with the actually measured mechanical parameters. If the mechanical parameter deviates from the target value or target value range by a certain threshold, the sealing of the annular gap can begin.

[0040] According to one embodiment, it is proposed that not only a mechanical parameter, but also a temporal gradient of a mechanical parameter, be determined. Changes in the structure can also be detected using a gradient. Such gradients, like the target values, can be simulated in advance, and the grouting process can begin if a deviation occurs. The metrological data acquisition can be supported, supplemented, or replaced by visual inspections to arrive at an assessment of structural integrity and stability.

[0041] According to one embodiment, it is proposed that the strength of the potting compound is determined based on a predetermined remaining service life of the structure and decreases with decreasing remaining service life. The mechanical properties of the potting compound can be adjusted. In particular, strength can be one such mechanical property. A service life is predetermined for the structure. The mechanical parameter is recorded during the service life, i.e., after initial commissioning. The remaining service life can also be recorded. The shorter the remaining service life, the less suitable the potting compound needs to be for permanently protecting the structure. Thus, the strength of the potting compound can also decrease with decreasing remaining service life in order to protect the structure from mechanical damage until the end of its service life.

[0042] According to one embodiment, it is proposed that steel pipe segments or reinforced concrete segments be used as pipe segments. A combination of these two materials is possible.

[0043] It is also proposed that cylindrical or conical pipe segments be used, at least in the area of ​​the annular gap. The joining elements can also be conical, in particular.

[0044] Pipe segments from offshore structures are preferably used. These typically possess material properties that are suitable for the conditions found in offshore environments. In particular, fatigue strength against saltwater may be necessary.

[0045] According to one embodiment, it is proposed that the pipe segments be positioned concentrically to each other, forming an annular gap between them. In particular, the joining elements are arranged on the outer surfaces of the pipe segments such that, in the connected state, they can position the pipe segments concentrically to each other.

[0046] According to one embodiment, it is proposed that the outer and / or inner pipe segment has at least one shear rib in the region of the annular gap, wherein the at least one shear rib is arranged at least substantially circumferentially, preferably completely circumferentially, on the pipe segment, and in particular that the at least one shear rib is arranged at least substantially annularly on the pipe segment. However, a shear rib can also be arranged circumferentially only in angular segments. A shear rib can be arranged like a joining element on a lateral surface of the pipe segment in the region of the annular gap. A shear rib can, in particular, extend in a plane perpendicular to the longitudinal axis of the pipe segment. However, shear ribs are smaller in their radial extent than the joining elements, so that the shear ribs preferably do not come into contact with the other pipe segment.The shear ribs are designed so that, in the case of casting, the casting compound fits snugly around the shear ribs, thus creating a positive connection between the casting compound and the respective pipe segment.

[0047] According to one embodiment, it is proposed that a grout mortar and / or a grout be used as the grout compound. This grout is, in particular, an expanding grout. An alkali silicate can be used as a reactive aggregate. Aggregates of bentonite, calcium (preferably <15 wt%), sulfoaluminum cements, and / or aluminate are also possible. The sum of the aggregates is preferably <60 wt%.

[0048] According to one embodiment, it is proposed that a grout mortar and / or a grout with a cube compressive strength of more than 60 MPa, preferably more than 90 MPa, and in particular more than 120 MPa, be used as the grout.

[0049] The connection between the pipe segments is located in an area below the water level. The compressive strength is determined according to DIN EN 12390, ASTM C39, or ASTM C873.

[0050] According to one embodiment, it is proposed that the longitudinal distance between the two joining elements of a lateral surface be such that it is at least 0.5 times the diameter of the inner tube segment, in particular the outer diameter of the inner tube segment, preferably at least 1 time this diameter, and more preferably at least 1.5 times this diameter. However, the distance between the joining elements is preferably less than 3 times this diameter. The diameter can refer to either the inner or the outer diameter of the inner tube segment. Preferably, the distance is that between the effective surfaces of the joining elements, i.e., in particular, between the joining surfaces of the joining elements.

[0051] It is also proposed that the ratio between the outer diameter of the annular gap to its radial spread, i.e. the distance between the pipe segments in the radial direction to each other, be designed such that it is at least 20 and less than 150, in particular less than 100, ideally less than 45.

[0052] To facilitate subsequent filling with the potting compound, it is proposed that the potting compound be introduced into the annular gap through at least one opening in the inner pipe segment. Alternatively, at least one joining element may be provided with a closable opening that can be opened for potting, thus allowing the potting compound to be introduced into the annular gap.

[0053] The subject matter will be explained in more detail below with reference to a drawing showing an exemplary embodiment. The drawing shows: Fig. 1 an offshore wind turbine according to an embodiment; Fig. 2 two nested pipe segments according to an embodiment; Fig. 3 two nested pipe segments according to an embodiment; Fig. 4 the sequence of a method described.

[0054] Fig. 1 Figure 2 shows a wind turbine 2, which is installed offshore. The foundation structure of the wind turbine 2 includes a monopile 4. The monopile 4 is a pipe segment that is founded in the seabed 6. The method by which a monopile 4 is founded in a seabed 6 is known per se.

[0055] A transition piece 8, which is also a pipe segment, is arranged on the monopile 4 either below or above the water level. A boat landing platform 8a may be provided on the transition piece 8.

[0056] A tower 10 of the wind turbine, on which the wind turbine with a nacelle 12 is arranged, is attached to the transition piece 8. The basic structure of the wind turbine 2 with tower 10 and nacelle 12 is known per se.

[0057] Monopile 4 and Transition Piece 8 are described below as examples. The descriptions also apply analogously to other pipe segments of a structure, such as a drilling platform or the like.

[0058] The connection between the monopile 4, formed as a pipe segment, and the transition piece 8, formed as a pipe segment, is explained in more detail using the example of all conceivable pipe segments.

[0059] In the following description, Transition Piece 8 is always inserted as the upper pipe segment into Monopile 4 as the lower pipe segment. However, the description also applies analogously if Transition Piece 8 is placed over Monopile 4 as the lower pipe segment. A key feature of this method is that the connection between the pipe segments, in this case between Monopile 4 and Transition Piece 8, is designed as a so-called double slip joint, and an annular space between the pipe segments and the joining elements can be filled after commissioning, if necessary, depending on measured values ​​and mechanical parameters.

[0060] Fig. 2 Figure 1 shows a longitudinal section through such a connection. The monopile 4 is visible. A first joining element 14a is arranged on the inner surface of the monopile 4 in the region of an end-face opening 4a. In the example shown, the first joining element 14a is formed by a corresponding profile of the opening cross-section of the tube element. A second joining element 14b is arranged on the inner wall of the monopile 4 at a longitudinal distance 18 from the end-face opening 4a. Both joining elements 14a and 14b taper towards the end-face opening 4a and are preferably conically shaped.

[0061] Transition Piece 8 also has joining elements 16a and 16b on its outer surface. Joining element 16a is located at an end face opening 8a of Transition Piece 8. Here, too, joining element 16a can be formed by a corresponding profile of the wall of Transition Piece 8 in the region of the end face opening 8a. At a longitudinal distance 18 from the end face opening 8a, another joining element 16b is formed on the outer surface of Transition Piece 8. Joining elements 16a and 16b also taper towards the end face opening 8a and are preferably conical.

[0062] The preferably conical tapers of the joining elements 14a, 16b and 14b, 16a respectively have corresponding, complementary profiles. This results in the joining elements 14a, 16b and 14b, 16a being in direct contact with each other at their facing surfaces, the so-called joining surfaces, when installed. The joining elements 14, 16 are shaped such that an annular space 20 is formed between the pipe segments, in particular the transition piece 8 and the monopile 4, when installed. An opening 22 is provided in the wall of the transition piece 8, which can be opened and / or closed from the inside in order to fill the annular space 20 with potting compound, as will be described below.

[0063] Fig. 3 Figure 1 shows another embodiment of a monopile 4 with a transition piece 8 inserted therein. In contrast to the Fig. 2 The joining elements 14a, 16b are not located directly at the end face of Transition Piece 8 or Monopile 4, but are arranged offset in the longitudinal direction 18 from the end face. Here again, the joining elements 14a, 16b and 14b, 16a are complementary to each other, so that in the joined state corresponding joining surfaces are in contact with one another. Here too, an annular space 20 is formed.

[0064] Fig. 4 This shows the sequence of a given procedure. In step 30, a simulation of a connection between two pipe segments 4 and 8 is first performed, in particular according to the Figuren 2 and 3This is carried out to verify their load-bearing capacity and mechanical response to mechanical stress. Various mechanical parameters, already mentioned above, are simulated, and the limits within which these parameters can fluctuate without causing damage to the structure are determined. For the various parameters, target values ​​or target value ranges are simulated, indicating how the mechanical parameter can change or within what range it can lie without damaging the structure.

[0065] Using the values ​​obtained in this way, a connection between monopile 4 and transition piece 8 is actually constructed in step 32. In this step, the structure is actually erected in-situ and put into operation. During construction, in step 34, at least one sensor, preferably a plurality of sensors, is arranged on the pipe segments 4, 8 and / or the joining elements 14, 16.

[0066] After commissioning, the measured values ​​recorded by the sensors are continuously monitored in step 36. Measurements can be taken at defined intervals (1 minute, 5 minutes, 15 minutes, etc.) or continuous monitoring can be performed. The recorded measured values ​​correspond to the previously simulated mechanical parameters.

[0067] In step 38, the measured mechanical parameter is compared with the simulated target value or target value range. If the actual value lies within the target value or target value range, particularly below or above a limit value, the process branches back to step 36 in step 38a. However, if one or more of the parameters lie outside the target value range or by a limit value outside a target value, the process branches to step 40 in step 38b.

[0068] In step 40 a warning signal is issued, which in step 42 leads to the annular space 20 being filled with a potting compound, in particular grout.

[0069] For this purpose, an assembly team is commissioned to carry out grout work on the already constructed structure. The assembly team preferably travels to the structure using a suitable assembly vessel. A supply line is routed through an opening (not shown) to opening 22 within transition piece 8. Opening 22 is opened, and grout is poured into the annular space 20 through it. After the annular space 20 is preferably completely filled, opening 22 is closed again, and the grout is allowed to harden. After the grout has hardened, a grout connection is formed. This grout connection is mechanically designed so that the grout has sufficient strength to protect the structure from damage. This strength is selected to ensure that the structure remains mechanically stable until the end of its predicted service life.

[0070] Using the described method, it is therefore possible to deploy double slip joints in the field without knowing their long-term stability. Should such structures be at risk of damage or have already been damaged during their service life, particularly at the double slip joint, this method allows for subsequent grouting, transforming the double slip joint into a grout connection that ensures sufficient mechanical stability for the remainder of its service life.

Claims

1. Method for establishing a connection between two pipe segments of a tower-like structure, in particular a wind turbine (2), in which a first pipe segment is pushed into a second pipe segment at an end face or a first pipe segment is placed over a second pipe segment at an end face and an annular space (20) is formed between the first and the second pipe segment, two at least partially circumferential joining elements, spaced apart from one another in the longitudinal direction (18) of the pipe segments are arranged in the annular space (20), wherein the joining elements are arranged on an outer wall of one of the pipe segments and / or on an inner wall of one of the pipe segments, and the pipe segments are mechanically coupled to one another via the joining elements in the annular space (20), characterized in that a mechanical parameter of the mechanical coupling between the pipe segments is detected by means of at least one measuring device on at least one of the pipe segments, and - that, depending on the detected mechanical parameter, the annular gap is filled with grouting compound after an initial installation and commissioning of the structure.

2. Method according to claim 1, characterized in that - the pipe segments are coupled mechanically to one another by the joining elements in the manner of a double-slip joint and / or - joining elements corresponding to one another on the pipe segments are arranged so that the joining elements corresponding to one another are in contact to one another in the coupled state and / or - at least one of the joining elements tapers towards an end face of the pipe segment.

3. Method according to one of the preceding claims, characterized in that - at least one of the following is used as a mechanical parameter: - expansion of the pipe segment, - compression of the pipe segment, - vibration of the pipe segment, - acceleration of the pipe segment, - relative movement of the pipe segments with respect to one another, - a natural frequency of the structure, - a change in the natural frequency of the structure, - a response behaviour, in particular in the frequency range of the structure, - a stress / strain value of the pipe segment.

4. Method according to one of the preceding claims, characterized in that - the detected mechanical parameter is compared with a nominal value and, in case of a deviation above a limit value, the annular gap is filled with grouting compound.

5. Method according to one of the preceding claims, characterized in that - a time gradient of the detected mechanical parameter is compared with a nominal value and, in case of a deviation above a limit value, the annular gap is filled with casting compound.

6. Method according to one of the preceding claims, characterized in that - the strength of the grouting compound is determined as a function of a predetermined remaining period of operation of the structure and is reduced as the remaining period of operation decreases.

7. Method according to one of the preceding claims, characterized in that - steel pipe segments or reinforced concrete are used as pipe segments and / or - cylindrical or conical pipe segments, at least in the region of the annular gap, are used as pipe segments and / or - pipe segments of an offshore structure are used as pipe segments and / or - tower segments of a wind power installation (2), in particular of an offshore wind power installation (2), are used as pipe segments.

8. Method according to one of the preceding claims, characterized in that - the pipe segments are positioned concentrically to one another, forming the annular gap between the pipe segments.

9. Method according to one of the preceding claims, characterized in that the outer pipe segment and / or the inner pipe segment has at least one thrust rib in the region of the annular gap, wherein in particular the at least one thrust rib is arranged at least substantially circumferentially on the pipe segment, in particular that the at least one thrust rib is arranged at least substantially annularly on the pipe segment.

10. Method according to one of the preceding claims, characterized in that - a grout and / or a grouting mortar is used as the grouting compound, in particular that a grout which expands during hardening, a so-called expansive grout, is used, and / or that a grout is used which has alkali-silica reactive aggregates, admixtures of bentonite, calcium sulfo aluminate cements and / or aluminate.

11. Method according to one of the preceding claims, characterized in that - a grouting mortar and / or a grout with a cube compressive strength of more than 60 MPa, preferably more than 90 MPa, in particular more than 90 MPa, is used as the grouting compound.

12. Method according to one of the preceding claims, characterized in that the structure is an offshore structure and in that the mechanical coupling between the pipe segments is arranged below the water level.

13. Method according to one of the preceding claims, characterized in that - the distance between the two joining surfaces in the longitudinal direction (18) to one another in the annular gap is configured such that it is at least 0.5 times the diameter of the inner pipe segment, preferably at least 1 times the diameter of the inner pipe segment, in particular at least 1.5 times the diameter of the inner pipe segment, preferably not more than 3 times the diameter of the inner pipe segment.

14. Method according to any preceding claim, characterized in that - the ratio between an external diameter of the annular gap and its radial extent is designed such that it is at least 20.

15. Method according to one of the preceding claims, characterized in that the grouting compound is introduced into the annular gap via an opening (22) in the inner pipe segment or that the grouting compound is introduced into the annular gap via an opening in at least one of the joining elements.