ACCUMULATIVE SLIDING CONSTRUCTION METHOD OF SEGMENTAL TRACK-CHANGING FOR UNEQUAL-SPAN STRUCTURE

Abstract

Provided is an accumulative sliding construction method of segmental track-changing for unequal-span structure, which divides the unequal-span structure into at least two sliding sections according to span variation, and a plurality of track segments corresponding to the spans of each sliding section. By providing sliders on the main truss/beam of each sliding section at positions corresponding to the track segments that each main truss/beam need to pass through, the sliding section smoothly passes through the sliding track segments to be in position; in addition, the main truss/beam of each sliding section is provided with temporary lengthening auxiliary structure or divided into an initial-mounted unit and rear-mounted units to allow the main truss/beam of each sliding section to pass through the track segments smoothly and to be in place.

Claims

1. An accumulative sliding construction method of segmental track-changing for unequal-span structure, the unequal-span structure includes at least three main trusses/beams with different spans, wherein the construction method comprises the following steps: Step 1, designing a sliding track; dividing the unequal-span structure into at least two sliding sections and an individual truss/beam according to structural span variation, wherein each sliding section comprises a sliding main truss/beam and a set of secondary trusses/beams connected; the sliding track is designed into a plurality of parallel track segments, the number of the track segments is equal to the number of the sliding sections, each track segment is offset from the adjacent track segment by a certain distance, and the certain distance is respectively corresponding to the span differentials between every two adjacent main trusses/beams; Step 2, analyzing the sliding process of the unequal-span structure; the weight of the sliding structure and the track layout, the specification, quantity and layout of the sliding hydraulic thrusters are determined; Step 3, installing the track segments and an assembly platform; the track segments are arranged according to the design of step 1, and the assembly platform used to assemble the structure is mounted to a first track segment where the sliding process begins, wherein the first track segment extends onto the assembly platform; Step 4, sliding process begins; a first main truss/beam is assembled on the assembly platform, and pushed away from the assembly platform by a set of hydraulic thrusters, wherein at least one assembled temporary auxiliary device for anti-overturning is arranged for preventing the first main truss/beam from overturning during the sliding process; after the first main truss/beam leaving the assembly platform, a second main truss/beam is assembled on the assembly platform, and at least one set of secondary trusses/beams is connected between the first main truss/beam and the second main truss/beam to form a first sliding section, then the assembled temporary auxiliary device for anti-overturning is detached; Step 5, track-changing process; pushing the sliding section and the second main truss/beam in Step 4 forward by the hydraulic thrusters until the first main truss/beam reaches a position where the first track segment and its adjacent track segment, a second track segment overlaps; each main truss/beam is provided with at least one slider at positions corresponding to track gauges of the track segments that the main truss/beam slides through, ensuring the main truss/beam leaves the first track segment and slides on the second track segment to perform a track-changing process; after the engagement of the sliders on the main truss/beam and the second track segment, the sliders corresponding to the first track segments are removed for subsequent installation and sliding of the other main truss/beam; Step 6, accumulative sliding is implemented; assembling the subsequent main truss/beam on the assembly platform, connecting it to the prior main truss/beam by the secondary trusses/beams therebetween to form a sliding section, arranging the corresponding set of hydraulic thrusters to push the assembled sliding section to move forward, and repeating the work of the step 5 until the installation of the whole unequal-span structure is completed.

2. The method of claim 1, wherein the span of the main truss/beam is smaller than the track gauge of the track segment which the main truss/beam engages with, and both ends of main truss/beam are attached with assembled temporary lengthening auxiliary structures.

3. The method of claim 2, wherein the assembled temporary lengthening auxiliary structure includes a plurality of sub-units, the length of each sub-unit is determined by the differential between the track gauges of two adjacent track segments of the track segments.

4. The method of claim 3, wherein as the sliding main truss/beam passes one of the track segments, the sub-units corresponding to the one of the track segments are removed.

5. The method of claim 1, wherein the span of the main truss/beam is larger than the track gauge of the track segment that the main truss/beam engages with, and the main truss/beam is divided into an initial sliding unit and rear-mounted units that are installed at both ends of the initial sliding unit, wherein the span of the initial sliding unit is equal to the track gauge of the track segment.

6. The method of claim 5, wherein the rear-mounted units comprise a plurality of sub-units, and the length of each sub-unit corresponds to the differences in track gauges of two adjacent track segments of the track segments.

7. The method of claim 6, wherein as the sliding main truss/beam passes one of the track segments, the sub-units corresponding to the next one of the track segments are mounted.

8. The method of claim 6, wherein folding hinges are used for mounting the rear-mounted unit to the initial unit, as well as connection between sub-units of the rear-mounted units, and as the sliding main truss/beam passes one of the track segments, the sub-units corresponding to the next one of the track segments are unfolded.

9. The method of claim 3, wherein the connections between the main truss/beam and the assembled temporary lengthening auxiliary structure, the connections between the initial sliding unit and the rear-mounted unit, the connections between the sub-units of the assembled temporary lengthening auxiliary structure, and the connections between the sub-units of the rear-mounted unit are formed by channel steels and high strength bolts.

10. (canceled)

11. The method of claim 5, wherein the connections between the main truss/beam and the assembled temporary lengthening auxiliary structure, the connections between the initial sliding unit and the rear-mounted unit, the connections between the sub-units of the assembled temporary lengthening auxiliary structure, and the connections between the sub-units of the rear-mounted unit are formed by channel steels and high strength bolts.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0028] The present disclosure will be described hereinafter in details with reference to the figures and the embodiments, obviously, the figures to be described below are merely embodiments of the present disclosure. For those skilled in the art, other figures may be obtained according to these figures without any creative work.

[0029] FIG. 1 is a schematic plan view of unequal-span structure according to the first embodiment of the present disclosure;

[0030] FIG. 2 is a schematic diagram illustrating layout of a sliding track and equipment system according to the first embodiment of the present disclosure;

[0031] FIG. 3 is a schematic diagram of a first main truss/beam prepared for assembly according to the first embodiment of the present disclosure;

[0032] FIG. 4 is a schematic diagram illustrating the track-changing process according to the first embodiment of the present disclosure;

[0033] FIG. 5 is a further schematic diagram illustrating a track-changing process according to the first embodiment of the present disclosure;

[0034] FIG. 6 is a further schematic diagram illustrating the track-changing process according to the first embodiment of the present disclosure;

[0035] FIG. 7 is a schematic diagram illustrating the process of accumulative sliding construction of segmental track-changing according to the first embodiment of the present disclosure after being completed;

[0036] FIG. 8 is a schematic diagram of the sliding main truss/beam with an assembled temporary lengthening auxiliary structure according to the first embodiment of the present disclosure;

[0037] FIG. 9 is a detail drawing illustrating connection of the assembled temporary lengthening auxiliary structure according to the first embodiment of the present disclosure;

[0038] FIG. 10 is a cross sectional view of FIG. 9 along A-A;

[0039] FIG. 11 is a detail drawing of an assembled temporary auxiliary device for anti-overturning according to the present disclosure;

[0040] FIG. 12 is a cross sectional view of FIG. 11 along B-B;

[0041] FIG. 13 is a detail drawing of structure of a slider according to the present disclosure;

[0042] FIG. 14 is a detail drawing of a connection between the slider and the sliding main truss/beam according to the present disclosure;

[0043] FIG. 15 is a schematic diagram of arrangement of sliding track and equipment according to the second embodiment of the present disclosure;

[0044] FIG. 16 is a schematic diagram of a first main truss/beam prepared for assembly according to the second embodiment of the present disclosure;

[0045] FIG. 17 is a schematic diagram of the track-changing process according to the second embodiment of the present disclosure;

[0046] FIG. 18 is a further schematic diagram of the track-changing process according to the second embodiment of the present disclosure;

[0047] FIG. 19 is a further schematic diagram of the track-changing process according to the second embodiment of the present disclosure;

[0048] FIG. 20 is a schematic diagram illustrating the process of accumulative sliding construction of segmental track-changing according to the second embodiment of the present disclosure after being completed;

[0049] FIG. 21 is a schematic diagram illustrating division of an initial sliding unit and its rear-mounted units according to the second embodiment of the present disclosure;

[0050] FIG. 22 is a schematic diagram of the folding connection of the initial sliding unit and the rear-mounted units according to the second embodiment of the present disclosure;

[0051] FIG. 23 is a schematic diagram illustrating an unfolded state of the initial sliding unit and the rear-mounted unit according to the second embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

[0052] In order that the objectives, technical solutions, and advantages of the present disclosure will become more apparent, specific embodiments of the present disclosure will be further described with reference to the accompanying drawings.

Embodiment 1

[0053] Embodiment 1 of the present application is shown in FIGS. 1-14.

[0054] FIG. 1 illustrates a typical roof or floor of unequal-span structure including four main trusses/beams 21, 22, 23, 24, of different spans and three sets of secondary trusses/beams, 31, 32, 33, wherein every two adjacent main trusses/beams are connected by a set of secondary trusses/beams, and the whole structure is supported on structural columns 1.

[0055] When the sliding construction of the unequal-span structure is carried out by sliding from a side with larger-span to a side of smaller-span due to restriction of construction site conditions, the method of segmental track-changing for unequal-span structure includes the following steps.

[0056] (1) The sliding track is designed and arranged. As shown in FIG. 2, considering safety and economic factors, the unequal-span structure is divided into three sliding sections and a fourth truss/beam could be installed directly at the end according to the shape and size the unequal-span structure and the arrangement, wherein each sliding section includes a main truss/beam and a set of secondary trusses/beams connected.

[0057] According to the division of the unequal-span structure, the sliding track is divided into three track segments 61, 62 and 63 with different track gauges. The track gauge of each track segment corresponds to the span of a sliding section, and the distances that each track segment offsets from its adjacent track segment in the span direction is shown as L1, L2, respectively.

[0058] (2) Based on the analysis of the whole process of accumulative sliding, the weight of the sliding structure and the track layout, the specification, quantity and layout of the sliding hydraulic thrusters 71, 72, 73 and 74 are determined, as shown in FIG. 2.

[0059] (3) The track segments and assembly platform are installed. As shown in FIG. 3 and FIG. 11, the track beam 17, the track beam supporting structure 4, as well as the track segments 61, 62 and 63 are installed according to the design of step (1). And an assembly platform 8 used to assemble the structure is mounted on the track segments with larger track gauge, in this embodiment, namely the assembly platform 8 is installed on the track segment 63. After being assembled, the main truss/beam may leave the assembly platform 8 to slide along the track segment, so that the assembly platform 8 could be used for assembling the next main truss/beam, and the secondary truss/beam between the two main trusses/beams can be installed to form the sliding section of the main truss/beam left on the assembly platform 8. The rest parts could be assembled and mounted in a similar way.

[0060] The track segment 63 may extend onto the assembly platform as desired, as shown in FIG. 3.

[0061] (4) The sliding process begins. As shown in FIGS. 3-5 and 8, After being assembled on the assembly platform 8, the first main truss/beam 21 is attached with assembled temporary lengthening auxiliary structure 212 on both ends for engaging with the track segments 63, as the length of the first main truss/beam 21 is less than the track gauge of the track segments 63.

[0062] The first set of hydraulic thrusters 71 could be installed on the first main truss/beam 21 after the installation of the first main truss/beam 21 and the assembled temporary lengthening auxiliary structure 212, and then the first set of hydraulic thrusters 71 controlled by a computer control system is employed to push the first main truss/beam 21 to travel along the track segments 63.

[0063] (5) Track-changing process begins: track-changing process is required when the sliding structure, for example the first main truss/beam 21 is switched between the track segments due to different track gauges of track segments 61-63.

[0064] As shown in FIGS. 9 and 10, wherein FIG. 10 is a sectional view taken along A-A in FIG. 9. The sliding process of each main truss/beam is analyzed and the tracks that each main truss/beam successively slides through are determined, then sliders 91 could be arranged at corresponding positions of the main truss/beam and/or the assembled temporary lengthening auxiliary structure 212 for the track-changing process between the track segments with different track gauges. Taking the first main truss/beam 21 as an example:

[0065] 1. The first main truss/beam 21, which is of the minimum span length, needs to slide through all three track segments 63, 62 and 61 in sequence. As shown in FIG. 8, at least one assembled temporary lengthening auxiliary structure 212 is provided at both ends of the first main truss/beam 21 to allow the first main truss/beam 21 to slide through the track segments 63, 62, whose track gauge is greater than the span of the first main truss/beam 21. The assembled temporary lengthening auxiliary structures 212 are temporarily connected to lower chord 211 of the first main truss/beam 21 via channel steels 10 by high-strength bolts 111 and 112 respectively.

[0066] The length of the assembled temporary lengthening auxiliary structure 212 is determined by differentials of the track gauges of the track segments 61, 62 and 63, which is shown as L1+L2 in FIG. 2. For the sake of the facilitation of disassembling and assembling in the construction process, the assembled temporary lengthening auxiliary structure 212 includes a plurality of attachable sub-units, the length of each sub-unit is determined by the distance that each track segment offset from its adjacent track segment, as shown in FIGS. 9-10, the length of the sub-units is L1 and L2, respectively. The connection between the sub-units is shown in FIG. 9 and FIG. 10. Further, in at least one embodiment, chord members and web members 213 arranged on the assembled temporary lengthening auxiliary structure 212 as required are mounted by high-strength bolts. In addition, sliders 91 are arranged on the first main truss/beam 21 and the assembled temporary lengthening auxiliary structure 212 at positions that engage with the track segments 61, 62 and 63, as shown in FIG. 8.

[0067] 2. As shown in FIGS. 3-4, the first set of hydraulic thrusters 71 controlled by a computer control system is used to push the first main truss/beam 21 into an appropriate position, the second main truss/beam 22 and the corresponding assembled temporary lengthening auxiliary structure 212 are installed on the assembly platform 8, then a set of secondary truss/beam 31 could be installed to connect the first main truss/beam and the second main truss/beam to form a stable whole, as shown in FIG. 4. Upon completion of the above operation, the second set of hydraulic thrusters 72 is installed.

[0068] 3. The sets of hydraulic thrusters 71, 72 controlled by the computer control system is employed to push the first sliding section to advance until the first main truss/beam 21 reaches an overlap portion of two adjacent track segments, which is shown as the overlap portion of track segments 63 and 62 in FIG. 5.

[0069] 4. Then the first set of hydraulic thrusters 71 could be removed from the track segments 63 and installed at the track segments 62; and the sub-unit of length L2 of the assembled temporary lengthening auxiliary structure 212 for sliding on the track segments 63 could be removed. Afterwards, the first sliding section is pushed forward by the sets of hydraulic thrusters 71 and 72 controlled by the computer control system, and the track-changing process of the first main truss/beam 21 is completed by through the sliders 91 arranged on the first main truss/beam 21, as shown in FIG. 6.

[0070] As mentioned above, the overlap is long enough for removing the hydraulic thrusters from prior track segments and installing the hydraulic thrusters on the subsequent track segments. To facilitate the track-changing process, the prior track segments and the subsequent track segments could be provided with export free cuts and import free cuts, respectively, to facilitate detaching the slider 91 from the track segments 63 and engaging with the track segments 62.

[0071] (6) Accumulative sliding is implemented. The second main truss/beam is assembled on the assembly platform 8 and then it is connected with the first sliding main truss/beam by the secondary truss/beam therebetween according to design requirements to form a whole, after that respective set of hydraulic thrusters could be arranged. With reference to the method of substeps 3 and 4 of step (5), the assembly process and the track-changing sliding for the second and third sliding trusses/beams are sequentially completed. The fourth main truss/beam 24 is installed when all three sliding sections are in position, and the installation of the whole structure is completed, as shown in FIG. 7.

[0072] In the present embodiment, as shown in FIG. 11, before the first main truss/beam 21 is pushed to slide, an assembled temporary auxiliary device for anti-overturning 13 is arranged at the front and rear of the main truss/beam 21 in sliding direction. The assembled temporary auxiliary device for anti-overturning 13 is formed by welding stabilizing rods 131 and columns 132, which may be formed by section steel or steel plate. The stabilizer rod 131 includes a web plate at the end that is temporarily fixed to the connecting plate 141 or 142 arranged on the lower chord 212 of the main truss/beam through bolts. The assembled temporary auxiliary device for anti-overturning 13 is supported on the sliding rail 6n, and the distance L from the center line of the columns 132 to the center line of the main truss/beam 21 is not supposed to be less than 0.5 times the height H of the cross section of the main truss/beam 21. At least one slider 91 is arranged between the columns 132 and the track segments 63 to ensure a smooth sliding, and the sliders 91 may be formed by the steel key block or by welded steel plate.

[0073] After the first main truss/beam 21 and the second main truss/beam 22 are integrally connected, the assembled temporary auxiliary device for anti-overturning 13 arranged for the first main truss/beam 21 can be removed.

[0074] As shown in FIG. 11, one end of each of the hydraulic thrusters 71 is fixed to the connecting plate 142 arranged on the lower chord 212 of the main truss/beam by one or more pin shafts, and the other end is connected to a pushing base 12 at the other end through one or more pin shafts. The pushing base 12 formed by welded steel plates is supported on side dams 18 located on both sides of the sliding track during operation of the hydraulic thrusters 71. In the present embodiment, the track segments is preferably made of channel steel, as shown in FIGS. 11 and 12, wherein FIG. 12 is a sectional view of FIG. 11 taken along B-B. Side dams 18 are arranged on both sides of the track segments in direction along the length of the track by welding, and the spacing of the side dams 18 is matched with the stroke of the hydraulic thrusters.

[0075] FIG. 11 shows a detailed view of the support of the first main truss/beam during sliding, wherein the track segment 63 is fixed to the track beam 17 and at least one slider 91 is provided between the lower chord 212 of the main truss/beam and the track segment 63. The track beam 17 is supported on the track beam supporting structure 4, which is fixedly connected with the structural columns 1.

[0076] The structure of the slider 91 is shown in detail in FIG. 13, which is formed by welding an upper cover plate 19, a lower cover plate 20 and a web plate 21, wherein the lower cover plate 20 is shaped as sledge by bending upwards with a radius R in the sliding direction. The slider 91 is connected to the lower chord of the sliding structure by connecting parts 22, which is formed by welding at least one end plate 221 and L-shaped clamping plate 222. The end plate 221 is connected with the upper cover plate 19 of the slider 91 through bolts 23, and the clamping plate 222 is clamped with the lower flange of the lower chord of the sliding structure, as shown in FIG. 14.

1. Embodiment 2

[0077] Embodiment 2 of the present application is shown in FIGS. 15-23.

[0078] When the unequal-span roof or floor structure in the first embodiment shown in the FIG. 1 is constructed by sliding from the small-span side to the large-span side of the structure, the method comprises the following steps.

[0079] (1) The sliding track is designed and arranged. As shown in FIG. 15, the design of the sliding track is the same as that of the first embodiment, but since the sliding direction is reversed, the track segments thereof and the sliders 91 are numbered in reverse order.

[0080] The track segments, the track beam, the track beam support structure, the sliders 91, and the connection between the sliders 91 and the sliding main trusses/beams are same as those in the first embodiment, as shown in FIGS. 11-14.

[0081] (2) Based on the analysis of the whole process of accumulative sliding, the weight of the sliding structure and the track layout, the specification, quantity and layout of the sliding hydraulic thrusters 71, 72, 73 and 74 are determined, as shown in FIG. 15.

[0082] (3) The track segments and assembly platform are installed. As shown in FIG. 16, the track beam 17, the track beam supporting structure 4 and the track segments 61, 62 and 63 are installed according to the design of step (1), and an assembly platform 8 used to assemble the sliding structure is mounted to the sliding track at the end with smaller track gauge. The sliding structure could be assembled and pushed off the assembly platform 8 section by section, such that each sliding section could be assembled and slid from the assembly platform to the other end of the sliding track.

[0083] (4) The first main truss/beam is pushed to slide initially.

[0084] 1. Initial sliding is prepared. The first main truss/beam 24 is divided into an initial sliding unit 24a and rear-mounted units. The span of initial sliding unit 24a matches the track gauge of the track segments 63. The rear-mounted unit is divided into a plurality of sub-units, the length of each sub-unit is determined by the differential between the track gauges of two adjacent track segments, as shown in FIG. 21, the length of the rear-mounted sub-units is L1 and L2, respectively. The initial sliding unit 24a and corresponding sliders 91 are assembled on the assembly platform 8, as shown in FIG. 16.

[0085] 2. The assembled temporary auxiliary device for anti-overturning 13 and the first set of hydraulic thruster 71 are arranged at the front and rear of the initial sliding unit 24a in its sliding direction, as shown in FIG. 11 of the first embodiment. After the above preparation work, the first set of hydraulic thrusters 71 is controlled by the computer control system to push the initial sliding unit 24a of the first main truss/beam 24 to slide.

[0086] (5) The track-changing process for each sliding section is performed. The sliding process of each sliding section is analyzed and the tracks that each sliding section successively slides through are determined, then the sliders 91 could be arranged at corresponding positions of the initial sliding unit 24a and the rear-mounted unit for track-changing between track segments with different track gauges. Taking the first sliding main truss/beam 24 as an example:

[0087] 1. The first main truss/beam 24, which is of the largest span length, needs to slide through all three track segments 63, 62 and 61 in sequence. As shown in FIG. 16, the span of the first main truss/beam 24 is larger than the track gauges of the track segments 63 and 62, therefore the first main truss/beam 24 is divided into the initial sliding unit 24a and the rear-mounted units, which is shown in FIG. 21 and substep 1 of step (4), to enable the first main truss/beam 24 to slide through the track segments 63 and 62.

[0088] 2. The initial sliding unit 24a is assembled on the assembly platform 8 together with corresponding sliders 91 and the first set of hydraulic thrusters 71, as shown in FIG. 16. The first set of hydraulic thrusters 71 is controlled by the computer control system to push the initial sliding unit 24a of the first main truss/beam to move to an appropriate position, allowing the initial sliding unit 23a of the second main truss/beam and corresponding sliders 91 to be assembled and installed on the assembly platform 8, then one or more secondary trusses/beams 33 are connected between the first main truss/beam and the second main truss/beam to form into a stable whole, as shown in FIG. 17. Upon completion of the above operation, the second set of hydraulic thrusters 72 could be installed and the assembled temporary auxiliary device for anti-overturning 13 for the first initial sliding unit 24a could be removed.

[0089] 3. The sets of hydraulic thrusters 71 and 72 is controlled by the computer control system to push the sliding section containing the initial sliding unit 24a forward until the initial sliding unit 24a reaches the overlap portion of the track segments, which is shown as the overlap portion of track segments 63 and 62 in FIG. 18.

[0090] 4. Rear-mounted units 24b with length of L1, which is corresponding to the track gauge between the track segments 62 and the track segments 63, are assembled at both ends of the initial sliding unit 24a. The first set of hydraulic thrusters 71 is removed from the track segments 63 and installed at the track segments 62, as shown in FIG. 19. Then the sets of hydraulic thrusters 71 and 72 could be controlled by the computer control system to push the sliding section forward further that is the sliding could be continued after the track-changing. The rear-mounted unit may be installed in high-altitude spread operation.

[0091] Preferably, the sub-units 24B and 24C of the rear-mounted unit may be pre-connected to the initial sliding unit 24a by dedicated hinges 27, when sliding through a track segments with smaller track gauges, the subunits could be folded, as shown in FIG. 22, to reduce being obstructed. The sub-units 24b, 24c could be unfolded successively by means of the dedicated hinge 27, as the sliding structure reaches track segments with wider track gauges to engage with corresponding track segments, as shown in FIG. 23.

[0092] The overlap is long enough for removing the hydraulic thrusters from prior track segments and installing the hydraulic thrusters on the subsequent track segments. To facilitate the track-changing process, the prior track segments and the subsequent track segments could be provided with export free cuts and import free cuts, respectively, to facilitate detaching the slider 91 from the track segments 63 and to engage with the track segments 62.

[0093] (6) Accumulative sliding is implemented. The second sliding main truss/beam is assembled on the assembly platform 8 and then it is connected with the first sliding main truss/beam by the secondary truss/beam therebetween according to design requirements to form a whole, after that respective set of hydraulic thrusters could be arranged. With reference to the method of substeps 3 and 4 of step (5), the assembly process and the track-changing sliding for the second and third sliding trusses/beams could be sequentially completed. The fourth sliding main truss/beam 21 could be installed when all three sliding sections are in position, and the installation of the whole structure is completed, as shown in FIG. 20.

[0094] The above embodiments describe the sliding construction for unequal-span structure comprising four main trusses/beams with different spans and three sets of secondary trusses/beams. In actual construction, the method can be applied to sliding construction for unequal-span structure including different numbers of main trusses/beams with different spans. For example, for the unequal-span structure whose number of main trusses/beams with different spans is n, to apply sliding construction according to the present application, the number of track segments could be n−1, and the number of hydraulic thrusters, etc. could be n.