Construction method of flexible immersed tube joint

Abstract

The invention relates to the technical field of underwater engineering, in particular to a construction method of a flexible immersed tube joint, the immersed tube joint comprises a plurality of tube joint sections, and the construction method comprises the following steps: S1, assembling an anti-shear structure; s2, pipe joint sections are prefabricated; s3, forming a rigid pipe joint system; s4, converting the rigid pipe joint system into a flexible pipe joint system; the stress between the pipe joint sections is transmitted and released through the shear rods, uniform transmission of the stress can be achieved, the shear rods can adapt to deformation of the two adjacent pipe joint sections in any direction, meanwhile, movement between the pipe joint sections is more uniform and gentle, and the construction method is easy to operate, safe, efficient and suitable for large-scale popularization and application. The length limitation of a rigid immersed tube structure is broken through, and the length of a single immersed tube section can be greatly prolonged, so that the number of times of prefabricating, floating and immersing the immersed tube is reduced, and the construction risk is effectively reduced; and meanwhile, the flexible pipe joint structure can well adapt to differential settlement of a foundation, the adaptability to the foundation is better, the structural stability is remarkably improved, and the structure is safer and more durable.

Description

Technical Field

[0001] The invention relates to the technical field of underwater engineering, and in particular to a construction method for a flexible immersed tube segment. Background Art

[0002] As engineering immersed tube tunnel technology becomes increasingly mature, it is increasingly widely used in cross-regional transportation and can be applied to underwater construction environments of various geotechnical types, greatly accelerating the development of cross-river and cross-sea transportation in my country.

[0003] At present, in immersed tube tunnels, steel shear keys are usually used between the segments of rigid prefabricated immersed tubes. They need to be installed again after the concrete is poured. Due to the small space inside the tube, the installation of steel shear keys is difficult and inefficient. Due to the mechanical properties of concrete and steel shear keys, the prefabricated length of a single segment of a rigid immersed tube is greatly limited, and it is easy to produce large deflections. In addition, steel shear keys are usually only distributed on the outside of the tube segment and the middle partition wall. After the tube segment is sunk and the prestressed bundle is cut off, the shear force between the segments is only concentrated at the shear key position, and can only eliminate vertical shear stress. The stress release between the segments is not uniform, the ability to adapt to differential settlement is weak, and there is a situation of local stress concentration. Especially for the rigid foundation of the rock foundation, it will affect the full release of stress between the structural segments and the ability to adapt to foundation deformation. It is easy to cause structural damage and water leakage due to differential settlement. At the same time, due to the thermal expansion and contraction of the concrete structure, uneven gaps are easily generated between two adjacent pipe segments. The waterstop between the two pipe segments with a larger gap is easily torn, causing the waterstop structure to fail. Summary of the invention

[0004] In view of the deficiencies existing in the above-mentioned prior art, the present invention provides a construction method for a flexible immersed tube segment which is simple in construction operation, safe and efficient.

[0005] The present invention provides a construction method for a flexible immersed pipe segment, wherein the immersed pipe segment comprises a plurality of pipe segment segments, a plurality of shear-resistant structures are evenly arranged between two adjacent pipe segment segments, the shear-resistant structures are used to release the stress between the pipe segment segments, the shear-resistant structures comprise a shear rod and a sleeve assembly sleeved outside the shear rod, the sleeve assembly comprises a first sleeve and a second sleeve butted in a horizontal direction, both ends of the first sleeve and the second sleeve are expansion sections, and the expansion sections are formed by gradually expanding outward along their axial direction; The construction method comprises the following steps: S1. Assemble shear structure: Install the first sleeve on one side of the shear rod, and then weld fixing plates above and below the edge of the first sleeve that is docked with the second sleeve. The fixing plates are coplanar with the end face of the first sleeve; install the second sleeve on the other side of the shear rod to form the shear-resistant structure; repeat step S1 to complete the assembly of the remaining shear-resistant structures. S2. Prefabrication of pipe sections: Prefabricate the pipe sections in the site area. The pipe sections prefabricated first are the precast sections, and the pipe sections prefabricated later are the post-cast sections. When prefabricating the precast sections, bind the steel bars, embed the prestressed ducts, erect the formwork, and fix the fixing plates on the end face formwork so that the first sleeve of the shear-resistant structure is located inside the precast sections. Then, pour the concrete for the precast sections, and the second sleeve is the free end. Carry out the prefabrication of the post-cast sections. The second sleeve is already at the prefabrication position of the post-cast sections. Bind the steel bars, embed the prestressed ducts, and make the prestressed ducts in the precast sections and the prestressed ducts in the post-cast sections form a pipeline that penetrates in the length direction; then carry out formwork erection and concrete pouring; after prefabrication, the shear rod is located between two adjacent precast sections and post-cast sections, and the prestressed steel strands in the prestressed ducts connect multiple pipe sections to form the integral immersed tube section. S3. Form a rigid pipe section system: After all the pipe sections are prefabricated and the concrete strength reaches the expected strength, tension the two ends of the prestressed steel strands at both ends of the immersed tube section. After the tensioning is completed, carry out grouting and anchor sealing operations. At this time, each pipe section is in a compressed state, and the immersed tube section forms a temporary rigid pipe section system. S4. Convert the rigid pipe section system to a flexible pipe section system: Carry out primary outfitting and secondary outfitting on the immersed tube section of the above rigid pipe section system. When the installation conditions are met, float the outfitted immersed tube section to the installation position and carry out sinking, docking, and installation operations. After the immersed tube section has settled stably, install the horizontal shear-resistant structure and vertical shear-resistant structure between the immersed tube sections, and cut the prestressed steel strands between two adjacent pipe sections. The immersed tube section is converted from a rigid pipe section system to a flexible pipe section system. The shear rod can conform to the deformation of the two pipe sections in any direction, and the stress between the two pipe sections is completely released through the shear rod. The expansion section prevents the first sleeve from being pulled out of the precast section or the second sleeve from being pulled out of the post-cast section.

[0006] The construction method of the flexible immersed tube segment of the present technical solution is simple in construction operation, safe and efficient. It solves the problem of stress concentration in the system conversion of the immersed tube segment from the process. The stress between the tube segments is transmitted and released through the shear rods, enabling uniform stress transmission. The shear rods can adapt to the deformation of two adjacent tube segments in any direction while ensuring the effectiveness of the shear-resistant structure, making the movement between the tube segments more uniform and gentle. The expansion sections at both ends of the first sleeve and the second sleeve are intermittently stressed in the horizontal direction. When the tube segment undergoes cold shrinkage, the first sleeve and the second sleeve are subjected to horizontal stress, limiting the displacement of the shear rod in the horizontal direction, and the gap deformation between two adjacent tube segments is uniform.

[0007] In some embodiments of the present application, the shear rod includes a circular rod portion with an equal diameter and tensile portions located at both ends of the circular rod portion. The tensile portions are formed by gradually expanding the circular rod portion axially outward; formed by gradually increasing the diameter. A first accommodation cavity for accommodating one side structure of the shear rod is provided in the first sleeve, and a second accommodation cavity for accommodating the other side structure of the shear rod is provided in the second sleeve. The tails of the first accommodation cavity and the second accommodation cavity are enlarged cavities for accommodating the tensile portions of the shear rod. The diameter of the circular rod portion is smaller than the inner diameters of the first accommodation cavity and the second accommodation cavity. Part of the circular rod portion extends into the enlarged cavity, and the minimum diameter of the tensile portion is larger than the inner diameter of the narrowest part of the enlarged cavity. In step S4, when two adjacent tube segments undergo horizontal displacement, the first sleeve or the second sleeve moves synchronously with the tube segment. When the narrowest part of the enlarged cavity of the first sleeve or the second sleeve moves into contact with the smallest diameter part of the tensile portion of the shear rod, the first sleeve or the second sleeve stops moving, which can limit the horizontal displacement between two adjacent tube segments, ensure relatively uniform displacement between each segment, and avoid tearing of the water stop structure between the tube segments.

[0008] In some embodiments of the present application, the first sleeve includes an upper sleeve and a lower sleeve that are butt-jointed in the up-down direction. The lower sleeve includes a straight portion and an enlarged portion. The side elevation projection surface of the straight portion is rectangular, and a semi-circular first groove corresponding to the circular rod portion is opened on its upper end surface. The side elevation projection surface of the enlarged portion is rectangular, and the front elevation projection surface is trapezoidal. A second groove corresponding to the shape of the tensile portion is opened on the upper end surface of the enlarged portion. The structures of the upper sleeve and the lower sleeve are mirror-symmetrical along the horizontal butt-joint surface; after the upper sleeve and the lower sleeve are butt-jointed, the two first grooves and the two second grooves are respectively butt-jointed to form a first accommodation cavity for accommodating the shear rod. In step S1, one side of the shear rod is correspondingly placed in the first groove and the second groove of the lower sleeve, the upper sleeve is correspondingly placed above the lower sleeve, and the joint of the upper sleeve and the lower sleeve is welded and fixed, and the installation of the first sleeve is completed; the second sleeve is installed on the other side of the shear rod in the same way.

[0009] In some embodiments of the present application, a thermoplastic sleeve is sleeved outside the round rod portion. The thermoplastic sleeve is used to fill the gaps between the round rod portion and the first accommodation cavity and the second accommodation cavity, and the thickness of the thermoplastic sleeve is greater than the gaps, so that the shear rod is in the central position of the first sleeve and the second sleeve, increasing the friction between the upper sleeve and the lower sleeve. In step S2, when pouring the first-cast segment, it can prevent the second sleeve from falling off and prevent the concrete slurry from entering through the gaps between the first sleeve or the second sleeve and the shear rod. In step S1, first, the thermoplastic sleeve is sleeved on the round rod portion of the shear rod, and then the shear rod is placed in the lower sleeve, and the lower sleeve is welded and fixed after being butted with the upper sleeve.

[0010] In some embodiments of the present application, the shear-resistant structures are uniformly distributed on the outer walls and middle partition walls of the first-cast segment and the second-cast segment. The first sleeve and the second sleeve are arranged parallel to the axis of the immersed tube segment.

[0011] In some embodiments of the present application, in step S1, the skip-joint method is used for prefabricating the tube segments. The first-cast segments are odd-numbered tube segments, and the second-cast segments are even-numbered tube segments, which improves the construction efficiency.

[0012] In some embodiments of the present application, before the construction of the tube segment, a sliding layer with a small coefficient of friction is laid on the bottom formwork, and then the steel bars are tied and the concrete is poured. In step S2, during the overall tensioning process, the tube segment slides relatively on the sliding layer. The sliding layer can not only prevent the tube segment from sticking to the bottom formwork concrete, but also reduce the frictional resistance when the tube segment slides.

[0013] In some embodiments of the present application, in step S1, mid-buried waterstops are also pre-buried in both the first-cast segment and the second-cast segment during prefabrication. After the tensioning of the immersed tube segment in step S2 is completed, a first waterstop is installed between two adjacent tube segments, and a Gina waterstop is installed at the joint of the tube segment at the end. In step S3, after the settlement of the immersed tube segment is stable, a second waterstop is installed at the joint of the tube segment at the end. The middle-embedded waterstop and the first waterstop form a double-channel flexible waterstop structure at the joints of two adjacent pipe segments, and at the same time, a flexible connection is formed between two adjacent pipe segments; the Gina waterstop and the second waterstop form a double-channel flexible waterstop structure at the joints of two adjacent immersed tube segments.

[0014] In some embodiments of the present application, in step S1, when each pipe segment is prefabricated, prestressed steel strand cutting pipes are buried at both ends thereof, and a wire saw is arranged inside the prestressed steel strand cutting pipes. In step S3, after the settlement of the immersed tube segment is stable, the prestressed steel strands are cut using the wire saw in the order from top to bottom, and the prestressed steel strand cutting pipes are blocked. After the prestressed steel strands are cut, the immersed tube segment forms a flexible tube segment, which can well adapt to the rocky rigid foundation and achieve a perfect fit of using flexibility to overcome rigidity.

[0015] In some embodiments of the present application, in step S3, after the installation of the immersed tube is completed, the ballast water tanks inside the immersed tube segment are removed, and at the same time, ballasting construction on the top of the tube is carried out, and the ballast structure of the immersed tube segment is changed from temporary ballast to permanent ballast; after the settlement of the immersed tube segment is stable, the prestressed steel strands are cut to form a flexible tube segment system.

[0016] Based on the above technical solutions, the construction method of the flexible immersed tube segment of the present invention is simple to operate, safe and efficient. The stress between the pipe segments is transmitted and released through the shear rods, and the uniform transmission of stress can be realized. The shear rods can conform to the deformation of two adjacent pipe segments in any direction, and at the same time make the movement between the pipe segments more uniform and gentle. The expansion sections at both ends of the first sleeve and the second sleeve are intermittently stressed in the horizontal direction. When the pipe segments shrink due to cold, the first sleeve and the second sleeve are affected by the horizontal stress and limit the displacement of the shear rod in the horizontal direction, and the gap deformation between two adjacent pipe segments is uniform. The shear-resistant structure can prevent uneven settlement and deformation between the pipe segments, break through the limitation of the rigid immersed tube structure in length, can greatly extend the length of a single immersed tube, thereby reducing the number of prefabrication, floating and sinking of the immersed tube, and effectively reducing the construction risk; at the same time, the better adaptability of the flexible tube segment to the foundation can better adapt to the differential settlement of the foundation, significantly improve the structural stability, be safer and more durable, and ensure the construction and operation quality of the immersed tube tunnel. There is no connection between two adjacent pipe segments except shear rods, embedded waterstop and the first waterstop, and the steel bars are discontinuous. A flexible connection is formed between the pipe segments, which is beneficial to the stress release between the pipe segments. The embedded waterstop and the first waterstop between two adjacent pipe segments form a double-channel flexible waterstop structure; the Gina waterstop and the second waterstop form a double-channel flexible waterstop structure between two adjacent immersed tube segments. At the same time, the immersed tube segment joints are flexible joints, which are beneficial to the stress release between the two immersed tube segments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 A schematic structural diagram of an immersed tube segment according to an embodiment of the present invention; Figure 2 A schematic cross-sectional view of a shear-resistant structure according to an embodiment of the present invention; Figure 3 It is a structural schematic diagram of a shear rod according to an embodiment of the present invention; Figure 4 For the present invention Figure 2 BB cross-sectional view; Figure 5 It is a schematic structural diagram of a lower sleeve according to an embodiment of the present invention; Figure 6 It is a structural schematic diagram of a shear rod according to another embodiment of the present invention; Figure 7 is a schematic cross-sectional structure diagram of a shear-resistant structure according to another embodiment of the present invention; Figure 8 For the present invention Figure 2 AA section view; Figure 9 It is a schematic diagram of the end surface structure of the precast segment of the present invention; Figure 10 It is a schematic diagram of the positional relationship between the prestressed pipe and the prestressed steel strand cutting pipe of the present invention; Figure 11 It is a structural schematic diagram of the left end surface of the E1 segment of the present invention; Figure 12 It is a schematic diagram of the end surface structure of the post-cast segment of the present invention; Figure 13 It is a structural schematic diagram of the right end surface of the E8 segment according to an embodiment of the present invention.

[0018] In the figure, 10, immersed tube section; 11, first cast section; 111, first tube section joint steel shear key; 12, post-cast section; 122, second tube section joint steel shear key; 20, shear structure; 21, shear rod; 211, round rod portion; 212, tensile portion; 22, first sleeve; 221, first accommodating cavity; 2211, first groove; 2212, second groove; 222, upper sleeve; 223, lower sleeve; 2231, straight portion; 2232, enlarged portion; 23, second sleeve; 231, second accommodating cavity; 24, expansion section; 241, enlarged cavity; 25, thermoplastic sleeve; 26, reinforcing plate; 27, fixing plate; 28, reinforcing ribs; 30, prestressed pipe; 31, prestressed steel strand cutting pipe. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0021] The terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Thus, a feature defined as "first", "second", and "third" may explicitly or implicitly include one or more of the features.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] This embodiment provides a construction method for a flexible immersed tube segment. Figure 1As shown, the immersed tube segment 10 includes eight segment sections, namely E1, E2, ..., E8, and 124 shear structures are evenly arranged between two adjacent segment sections, and the shear structures can release stress in all directions between the segment sections; like Figure 2 As shown, a shear-resistant structure 20 of an embodiment of the present application includes a shear rod 21 and a sleeve assembly sleeved outside the shear rod, the sleeve assembly includes a first sleeve 22 and a second sleeve 23 butted in a horizontal direction, both ends of the first sleeve 22 and the second sleeve 23 are expansion sections 24, and the expansion section 24 is a trumpet-shaped structure, which is gradually expanded outward along its axial direction; like Figure 3 As shown, the shear rod 21 includes a round rod portion 211 of equal diameter and a tensile portion 212 located at both ends of the round rod portion 211. The tensile portion 212 is a trumpet-shaped structure formed by the round rod portion 211 gradually expanding outward along the axial direction, and the diameter of the tensile portion 212 gradually increases. In order to allow the shear rod to be placed in the first sleeve 22 and the second sleeve 23, a first accommodating cavity 221 for accommodating the left side structure of the shear rod is provided in the first sleeve 22, and a second accommodating cavity 231 for accommodating the right side structure of the shear rod is provided in the second sleeve 23; The tail ends of the first accommodating cavity 221 and the second accommodating cavity 231 are enlarged cavities 241 for accommodating the tensile portion 212 of the shear rod 21 , and the enlarged cavities 241 are located in the expansion section 24 ; The diameter of the round rod portion 211 is smaller than the inner diameters of the first accommodating cavity 221 and the second accommodating cavity 231. Part of the round rod portion 211 extends into the enlarged cavity 241. The minimum diameter of the tensile portion 212 is larger than the inner diameter of the narrowest part of the enlarged cavity 241. When horizontal displacement occurs between two adjacent pipe segments, the first sleeve 22 or the second sleeve 23 moves synchronously with the pipe segment. When the narrowest part of the enlarged cavity 241 of the first sleeve 22 or the second sleeve 23 moves and contacts the smallest diameter part of the tensile portion 212 of the shear rod 21, the first sleeve 22 or the second sleeve 23 stops moving, which can limit the occurrence of small-segment horizontal displacement between two adjacent pipe segments, so that the gaps between each adjacent pipe segment are evenly distributed, avoiding the phenomenon that the gaps between two pipe segments are too large. like Figure 4 As shown, the first sleeve 22 of this embodiment includes an upper sleeve 222 and a lower sleeve 223 that are connected in the upper and lower directions; like Figure 5 As shown, the lower sleeve 223 includes a straight portion 2231 and an enlarged portion 2232. The side projection of the straight portion 2231 is rectangular, and a semicircular first groove 2211 corresponding to the round rod portion 211 is formed on its upper end surface. The side projection of the enlarged portion 2232 is rectangular, and the front projection is trapezoidal. The upper end surface of the enlarged portion 2232 is formed with a second groove 2212 corresponding to the shape of the tensile portion 212. The structures of the upper sleeve 222 and the lower sleeve 223 are mirror-symmetrical along the horizontal docking surface; after the upper sleeve 222 and the lower sleeve 223 are docked, the upper and lower two first grooves 2211 and the two second grooves 2212 form a first accommodating cavity 221 for accommodating the left side of the shear rod 21; The structure of the second sleeve 23 is symmetrical to that of the first sleeve 22 , and its structure will not be described in detail here.

[0024] Furthermore, a thermoplastic sleeve 25 is sleeved on the outer side of the round rod portion 211, and the thermoplastic sleeve 25 is used to fill the gap between the round rod portion 211 and the first accommodating cavity 221 and the second accommodating cavity 231, and the thickness of the thermoplastic sleeve 25 is greater than the gap, so that the shear rod 21 is in the center position of the first sleeve 22 and the second sleeve 23, which increases the friction with the upper sleeve 222 and the lower sleeve 223, blocks the joint between the first sleeve or the second sleeve, and prevents concrete slurry from entering from the gap between the first sleeve or the second sleeve and the shear rod.

[0025] As another embodiment of the present application, the shear rod 21 includes a round rod portion 211 of equal diameter and a tensile portion 212 located at both ends of the round rod portion 211. The difference from the previous embodiment is that the tensile portion 212 in this embodiment is a cylindrical structure with a diameter greater than the round rod portion 211, the tensile portion 212 is perpendicular to the axis of the round rod portion 211, and each end of the round rod portion 211 has at least two tensile portions 212, such as Figure 6 As shown, there are four tensile parts 212 at both ends of the round rod part 211. When adjacent pipe segments are subjected to horizontal shear force, the horizontal shear force can be dispersed to the four tensile parts 212 at both ends, so that the stress is evenly dispersed on the shear rod 21, and the uniform horizontal displacement between two adjacent pipe segments can be limited, so that the gaps between each adjacent pipe segment are evenly distributed, avoiding the phenomenon that the gap between two of the pipe segments is too large; it can also avoid that when the stress is too large, there is only one tensile part 212 at the end, and the stress is concentrated on the tensile part 212, causing the tensile part 212 structure to fail.

[0026] like Figure 7 As shown, the first sleeve 22 and the second sleeve 23 of the present embodiment are cylindrical structures or rectangular structures of equal diameters without expansion sections. In order to increase the connection strength between the first sleeve 22 and the second sleeve 23 and the concrete of the pipe segment and prevent the first sleeve 22 from being pulled out from the first cast segment or the second sleeve 23 from the later cast segment, a plurality of reinforcing ribs 28 are evenly distributed on the outer side walls of the first sleeve 22 and the second sleeve 23. The reinforcing ribs 28 increase the contact area between the first sleeve 22 and the second sleeve 23 and the concrete, thereby improving the firmness of the first sleeve 22 in the first cast segment and the second sleeve 23 in the later cast segment.

[0027] The tail end of the first accommodating cavity 221 of the first sleeve 22 is two enlarged cavities 241, and the two enlarged cavities 241 respectively accommodate the two tensile parts 212 on the left side of the shear rod 21. The tail end of the second accommodating cavity 231 of the second sleeve 23 is also two enlarged cavities 241, and the two enlarged cavities 241 respectively accommodate the two tensile parts 212 on the right side of the shear rod 21. The enlarged cavity 241 of this embodiment is a cylindrical cavity with a diameter larger than the tensile part 212. The first sleeve 22 includes an upper sleeve 222 and a lower sleeve 223 that are butt-jointed in the upper and lower directions. The upper end surface of the lower sleeve 223 is provided with a semicircular first groove 2211 corresponding to the round rod portion 211, and two semicircular second grooves 2212 corresponding to the shape of the tensile portion 212. The structures of the upper sleeve 222 and the lower sleeve 223 are mirror-symmetrical along the horizontal butt-jointed surface. After the upper sleeve 222 and the lower sleeve 223 are butt-jointed, the upper and lower first grooves 2211 and the two second grooves 2212 form a first accommodating cavity 221 for accommodating the left side of the shear rod 21. The structure of the second sleeve 23 is symmetrical to that of the first sleeve 22 , and its structure will not be described in detail here.

[0028] Similarly, a thermoplastic sleeve 25 is sleeved on the outer side of the round rod portion 211, and the thermoplastic sleeve 25 fills the gap between the round rod portion 211 and the first accommodating cavity 221 and the second accommodating cavity 231, and the thickness of the thermoplastic sleeve 25 is greater than the gap, so that the shear rod 21 is in the center position of the first sleeve 22 and the second sleeve 23, which increases the friction with the upper sleeve 222 and the lower sleeve 223, blocks the joint between the first sleeve or the second sleeve, and prevents concrete slurry from entering from the gap between the first sleeve or the second sleeve and the shear rod.

[0029] The construction method of the flexible immersed tube segment includes the following steps: First, assemble the shear-resistant structure, and put the thermoplastic sleeve 25 on the round rod portion 211 of the shear rod 21. Since the thermoplastic sleeve 25 has a certain elasticity, it can be inserted from the tensile portion 212 at one end of the shear rod 21, and gradually pull the thermoplastic sleeve 25 onto the round rod portion 211; The left tensile portion 212 and the round rod portion 211 of the shear rod 21 are placed in the second groove 2212 and the first groove 2211 of the lower sleeve 223 respectively, and the upper sleeve 222 is placed above the lower sleeve 223 respectively, and the joints of the upper sleeve 222 and the lower sleeve 223 are welded and fixed, and then the reinforcing plate 26 is welded to the vertical sides of the upper sleeve 222 and the lower sleeve 223 by fillet welding, as shown in FIG. Figure 8As shown, in order to increase the vertical bonding strength of the upper sleeve 222 and the lower sleeve 223, to prevent the upper sleeve 222 and the lower sleeve 223 from being separated when the shear rod 21 is deformed by force, causing the shear structure to fail, at this time, the first sleeve 22 is installed; then, the fixing plates 27 are respectively welded above and below the edge of the end face of the first sleeve 22 docking with the second sleeve 23, and the fixing plates 27 are coplanar with the end face of the first sleeve 22; the second sleeve 23 is installed on the right side of the shear rod 21 in the same way, and the end face of the second sleeve 23 does not need to be welded with the fixing plate 27; Repeat the above operation to assemble the remaining shear-resistant structures 20; Prefabricate pipe segments on site. Before prefabrication, measure and lay out, then lay the bottom mold, lay bamboo plywood and double-layer kraft paper on the bottom mold as a sliding layer. The bottom mold, as well as the laying of bamboo plywood and double-layer kraft paper as sliding layers, are all existing technologies and will not be elaborated here. Use the skip bin method to prefabricate pipe segments. The first-cast segments 11 are odd-numbered pipe segments. The first-cast segments in this embodiment are E1, E3, E5, and E7 segments. The later-cast segments are even-numbered pipe segments. The later-cast segments 12 in this embodiment are E2, E4, E6, and E8 segments. During prefabrication, the first-cast segments 11 and the later-cast segments 12 do not affect each other, and the first-cast segments 11 and the later-cast segments 12 do not affect each other, which simplifies the construction process and improves construction efficiency. The skip-bin method of interval construction can avoid the situation in which the next pipe section has to wait until the concrete strength of the previous pipe section reaches the standard before pouring, which greatly affects the construction efficiency and delays the construction period.

[0030] After the sliding layer of the bottom formwork is laid, the precast segments 11, i.e., E1, E3, E5, and E7, are precast and the steel bars are tied, such as Figure 9 - Figure 10 As shown, a prestressed pipe 30 and a prestressed steel strand cutting pipe 31 are buried, and a middle embedded water stop and a first water stop embedded part are also pre-buried, and the first water stop embedded part is a smaller Ω water stop; a prestressed steel strand is arranged in the prestressed pipe 30, and a rope saw is arranged in the prestressed steel strand; a support formwork is erected, and a fixing plate 27 is fixed to the end face formwork by bolts, so that the first sleeve 22 of the shear structure is located in the first cast segment, and 124 shear structures 20 are evenly pre-buried on the outer walls and the middle partition walls of the two end faces of the first cast segment 11, and then the concrete pouring of the first cast segment is carried out, at this time, the second sleeve is a free end, and due to the large friction between the thermoplastic sleeve 25 and the shear rod 21 and the inner wall of the second sleeve 23, the second sleeve 23 does not need other fixing measures; It should be noted that if Figure 1 As shown in , the left end face of the E1 segment is the end face of the pipe joint when it is butt-jointed with the previous adjacent immersed pipe segment. It is not necessary to install the shear structure 20, but it is necessary to pre-embed the first pipe joint steel shear key 111. The first pipe joint steel shear key 111 is the vertical shear structure between the pipe segments, such as Figure 9As shown, it is also necessary to pre-embed steel sealing door embedded parts (not shown in the figure), Gina water stop belts and second water stop belt embedded parts (not shown in the figure) for water stop between pipe sections. The second embedded part is a relatively large-sized Ω water stop belt. Then formwork erection and concrete pouring operations are carried out; After the precast of the first-cast segment 11 is completed, the precast of the second-cast segment 12, namely E2, E4, E6, and E8, is carried out. At this time, the second sleeve 23 is already in the precast position of the second-cast segment 12, as Figure 12 shown. Similar to the first-cast segment 11, steel bars are tied, prestressed ducts 30 are embedded, prestressed steel strands are threaded through the prestressed ducts, and prestressed steel strand cutting pipes 31 are provided. The prestressed ducts 30 in the first-cast segment 11 and the prestressed ducts 30 in the second-cast segment 12 form a longitudinally continuous duct; middle-buried water stop belts and first water stop belt embedded parts are pre-embedded; after the pouring of the second-cast segment 12 is completed, the first sleeve 22 of the shear structure 20 is located in the first-cast segment 11, the left half of the shear rod 21 is located in the first sleeve 22, the second sleeve is located in the second-cast segment 12, and the right half of the shear rod 21 is located in the second sleeve 23; The shear structure only needs to fix the fixing plate 27 on the formwork of the first-cast segment 11 to complete the installation. During the precast of the second-cast segment 12, there is no need to fix the shear structure, which simplifies the construction steps and improves the construction efficiency; Similar to the first-cast segment E1, the right end face of the second-cast segment E8 is the pipe joint end face when docking with the next adjacent immersed tube pipe section. There is no need to fix the shear structure 20. It is necessary to pre-embed a second pipe joint steel shear key 122 that matches the first pipe joint steel shear key 111 to achieve shear resistance in the vertical direction between the two immersed tube pipe sections, as Figure 13 shown. It is also necessary to pre-embed steel sealing door embedded parts (not shown in the figure), and Gina water stop belts and second water stop belt embedded parts (not shown in the figure). Then formwork erection and concrete pouring operations are carried out; Furthermore, the first sleeve 22 and the second sleeve 23 are arranged parallel to the axis of the immersed tube pipe section 10. Therefore, the shear rod 21 is also parallel to the axis of the immersed tube pipe section 10. The shear rod 21 can withstand stresses in any direction between the first-cast segment 11 and the second-cast segment 12 and deform in any direction.

[0031] After the precast of all the first-cast segments 11 and the second-cast segments 12 of the shear rod 21 is completed, wait for the concrete strength to reach the expected strength. Then, from the left end face of the E1 segment and the right end face of the E8 segment, the prestressed steel strands are tensioned. The tensioning is carried out in the order from the middle to both sides and from the bottom to the top. When tensioning, the first-cast segment 11 and the second-cast segment 12 slide relatively on the sliding layer, and the frictional resistance is small. After the tensioning is completed, grouting and anchor sealing operations are carried out. At this time, each pipe section is in a compressed state, and the immersed tube pipe section 10 forms a temporary rigid pipe section system; The immersed tube segment 10 of the above rigid tube segment system is outfitted once, including the installation of steel sealing doors at both ends, the first water stop belt between segments, the Gina water stop belt at the E1 and E8 joints, and temporary floating equipment inside the immersed tube. After the first outfitting is completed, the dry dock is filled with water, the immersed tube segment 10 floats, and then it is towed to the outfitting area for secondary outfitting; after the secondary outfitting operation is completed, the immersed tube segment 10 is towed to the storage area; when the gravel foundation bed is leveled and the installation conditions are met, the immersed tube segment 10 is floated to the installation position by an installation ship for sinking, docking, and installation; When the installation of the immersed tube segment 10 is completed, the side locking backfill and the general backfill on the top of the immersed tube segment 10 are carried out, and then the floating equipment such as the ballast water tanks inside the immersed tube segment are removed. At the same time, the top ballast operation is carried out, such as backfilling with block stones on the top of the tube. The ballast structure of the immersed tube segment 10 is changed from temporary water tank ballast to permanent block stone ballast; After the settlement of the immersed tube segment is stable, the first pipe joint steel shear key 111 and the second pipe joint steel shear key 122 of the vertical shear-resistant structure are installed. Grouting is carried out between the steel shear keys, and the concrete shear key of the horizontal shear-resistant structure is poured. The second water stop belt between the pipe segments, that is, the larger-sized Ω water stop belt, is installed to form a flexible pipe joint.

[0032] The embedded water stop belt and the first water stop belt form a double-channel flexible water stop structure between two adjacent precast segments 11 and postcast segments 12, and at the same time, two adjacent precast segments 11 and postcast segments 12 form a flexible connection; the Gina water stop belt and the second water stop belt form a double-channel flexible water stop structure between two adjacent immersed tube segments 10.

[0033] The shear rods 21 between the precast segment 11 and the postcast segment 12 resist shear. The shear rods 21 are evenly distributed and the force is evenly distributed. Then, in the order from top to bottom, the prestressed steel strands inside the prestressed steel strand cutting tube 31 are cut by a wire saw, and the prestressed steel strand cutting tube 31 is blocked. After the prestressed steel strands are cut, the immersed tube segment 10 is converted from a rigid tube segment system to a flexible tube segment system to form a flexible tube segment. The shear rods 21 can adapt to the deformation of the adjacent precast segment 11 and postcast segment 12 in any direction. The stress between the precast segment 11 and the postcast segment 12 is completely released through the shear rods 21, and it can well adapt to the rocky rigid foundation, achieving a perfect fit of using flexibility to overcome rigidity.

[0034] Since the minimum diameter of the tensile part 212 of the shear rod 21 is greater than the inner diameter of the narrowest part of the enlarged cavity 241; when the adjacent pre-cast segment 11 and post-cast segment 12 undergo a horizontal outward displacement, the first sleeve 22 is cast in the pre-cast segment 11, and the second sleeve 23 is cast in the post-cast segment 12. Therefore, the first sleeve 22 or the second sleeve 23 will move horizontally outward synchronously with the pre-cast segment 11 or the post-cast segment 12. When the narrowest part of the enlarged cavity 241 of the first sleeve 22 or the second sleeve 23 moves into contact with the smallest diameter part of the tensile part 212 of the shear rod 21, the first sleeve 22 or the second sleeve 23 is restricted by the tensile part 212 and stops moving, so that the horizontal displacement between the adjacent pre-cast segment 11 and post-cast segment 12 is within the allowable range of the design, avoiding tearing the embedded waterstop and the first waterstop between the pre-cast segment 11 and the post-cast segment 12 when the horizontal displacement is large, and affecting the waterstop effect between the pipe segments.

[0035] The reinforcing plate 26 increases the bonding strength of the upper sleeve 222 and the lower sleeve 223 in the vertical direction, preventing the upper sleeve 222 and the lower sleeve 223 from being separated when the shear rod 21 is deformed by force, resulting in the failure of the shear-resistant structure; the tensile part 212 will not be pulled out of the enlarged cavity 241 either, avoiding the shear rod 21 being pulled out of the first sleeve 22 or the second sleeve 23, resulting in the failure of the shear-resistant structure. Each pre-cast segment and post-cast segment can settle according to the foundation. Since there is no other connecting structure between the pre-cast segment 11 and the post-cast segment 12 except for the double-layer flexible waterstop structure formed by the shear rod, the embedded waterstop and the first waterstop, the steel bars are not continuous, and the shear rod 21 can deform in accordance with the settlement direction and settlement displacement of the pre-cast segment 11 and the post-cast segment 12, while making the movement between the pipe segments more uniform and gentle, completely releasing the stress between the pipe segments. The expansion segments at both ends of the first sleeve and the second sleeve are intermittently stressed in the horizontal direction. Since both the pre-cast segment and the post-cast segment are formed by concrete pouring, they will expand and contract due to temperature changes. When the pipe segments contract, the first sleeve and the second sleeve move horizontally to both sides with the pre-cast segment and the post-cast segment respectively, and the gap between the pre-cast segment and the post-cast segment becomes larger. The shear rod is subjected to a horizontal stress. When the cold shrinkage is the largest, the shear rod, the first sleeve and the second sleeve are all stressed. The expansion segments of the first sleeve and the second sleeve limit the horizontal displacement of the shear rod, and the gap deformation between two adjacent pipe segments is uniform, avoiding excessive deformation of a certain gap caused by uneven deformation and tearing the embedded waterstop and the first waterstop. The flexible pipe joint of the present application has a better adaptability to the foundation, can better adapt to the differential settlement of the foundation, significantly improves the structural stability, and is safer and more durable; on the other hand, it breaks through the length limitation of the rigid immersed tube structure, can greatly extend the length of a single immersed tube, thereby reducing the number of times of precasting, floating and sinking of the immersed tube, and effectively reducing the construction risk.

[0036] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.

[0037] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features. Without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A construction method for a flexible immersed tube segment, characterized in that: The immersed tube segment comprises a plurality of segment sections, and a plurality of shear-resistant structures are evenly arranged between two adjacent segment sections, and the shear-resistant structures are used to release the stress between the segment sections, and the shear-resistant structures comprise a shear rod and a sleeve assembly sleeved outside the shear rod, and the sleeve assembly comprises a first sleeve and a second sleeve butted in a horizontal direction, and both ends of the first sleeve and the second sleeve are expansion sections, and the expansion sections are gradually expanded outward along their axial direction; The construction method comprises the following steps: S1. Assemble shear structure: Install the first sleeve on one side of the shear rod, and then weld fixing plates above and below the edge of the first sleeve at the end face butting against the second sleeve, respectively, wherein the fixing plates are coplanar with the end face of the first sleeve; install the second sleeve on the other side of the shear rod to form the anti-shear structure; repeat step S1 to complete the assembly of the remaining anti-shear structures; S2. Prefabrication of pipe segments: Prefabricate the pipe segments in the site, the first prefabricated pipe segments are the first cast segments, and the later prefabricated pipe segments are the later cast segments. When the first cast segments are prefabricated, steel bars are tied, prestressed pipes are buried, formwork is erected, and the fixing plate is fixed on the end face formwork, so that the first sleeve of the shear resistant structure is located in the first cast segment, and then the concrete of the first cast segment is poured, and the second sleeve is a free end; When the post-cast segment is prefabricated, the second sleeve is already located at the prefabrication position of the post-cast segment, steel bars are tied, and prestressed pipes are buried, so that the prestressed pipes in the first-cast segment and the prestressed pipes in the post-cast segment form a pipe that penetrates in the length direction, and then formwork support and concrete pouring are performed; after prefabrication is completed, the shear rod is located between two adjacent first-cast segments and the post-cast segment, and the prestressed steel strands in the prestressed pipe connect the multiple pipe segments to form the integral immersed pipe segment; S3. Forming a rigid pipe joint system: After all the pipe segments are prefabricated, after waiting for the concrete strength to reach the expected strength, the two ends of the prestressed steel strands at the two ends of the immersed tube segment are tensioned, and after the tensioning is completed, grouting and anchor sealing operations are performed. At this time, each of the pipe segments is in a compressed state, and the immersed tube segment forms a temporary rigid pipe segment system; S4. Conversion of rigid pipe joint system to flexible pipe joint system: Performing primary outfitting and secondary outfitting on the immersed tube segment of the rigid segment system; When the installation conditions are met, the immersed tube segment after outfitting is floated to the installation position for sinking, docking and installation operations. After the settlement of the immersed tube segment is stable, the horizontal shear structure and the vertical shear structure between the immersed tube segments are installed, and the prestressed steel strands are cut between two adjacent tube segment sections. The immersed tube segment is converted from a rigid tube segment system to a flexible tube segment system, and the shear rod can adapt to the deformation of the two tube segment sections in any direction. The stress between the two tube segment sections is completely released through the shear rod, and the expansion section prevents the first sleeve from being pulled out of the first cast segment or the second sleeve from being pulled out of the later cast segment.

2. The construction method of the flexible immersed tube segment according to claim 1 is characterized in that: The shear rod comprises a round rod portion with equal diameter and tensile parts located at both ends of the round rod portion, wherein the tensile parts are formed by the round rod portion gradually expanding outward along its axial direction; A first accommodating cavity for accommodating a structure on one side of the shear rod is provided in the first sleeve, and a second accommodating cavity for accommodating a structure on the other side of the shear rod is provided in the second sleeve; The tail ends of the first accommodating cavity and the second accommodating cavity are enlarged cavities for accommodating the tensile portion of the shear rod; The diameter of the round rod portion is smaller than the inner diameter of the first accommodating cavity and the second accommodating cavity, a portion of the round rod portion extends into the enlarged cavity, and the minimum diameter of the tensile portion is larger than the inner diameter of the narrowest part of the enlarged cavity; In step S4, when two adjacent pipe segments are displaced in the horizontal direction, the first sleeve or the second sleeve moves synchronously with the pipe segment. When the narrowest part of the expansion cavity of the first sleeve or the second sleeve moves and contacts with the smallest diameter part of the tensile portion of the shear rod, the first sleeve or the second sleeve stops moving, which can limit the horizontal displacement between the two adjacent pipe segments, ensure that the displacement between the pipe segments is relatively uniform, and avoid the water stop structure between the pipe segments from being torn.

3. The construction method of the flexible immersed tube segment according to claim 2 is characterized in that: The first sleeve includes an upper sleeve and a lower sleeve connected in the upper and lower directions; The lower sleeve comprises a straight portion and an enlarged portion, the side projection of the straight portion is rectangular, and its upper end surface is provided with a semicircular first groove corresponding to the round rod portion, the side projection of the enlarged portion is rectangular, and the front projection is trapezoidal, and the upper end surface of the enlarged portion is provided with a second groove corresponding to the shape of the tensile portion; The structures of the upper sleeve and the lower sleeve are mirror-symmetrical along the horizontal butt joint surface; after the upper sleeve and the lower sleeve are butt jointed, the two first grooves and the two second grooves are butt jointed to form a first accommodating cavity for accommodating the shear rod; In step S1, one side of the shear rod is placed correspondingly in the first groove and the second groove of the lower sleeve, the upper sleeve is placed correspondingly above the lower sleeve, the joint between the upper sleeve and the lower sleeve is welded and fixed, and the installation of the first sleeve is completed; the second sleeve is installed on the other side of the shear rod in the same way.

4. The construction method of the flexible immersed tube segment according to claim 2 is characterized in that: A thermoplastic sleeve is sleeved on the outer side of the round rod portion, and the thermoplastic sleeve is used to fill the gap between the round rod portion and the first accommodating cavity and the second accommodating cavity, and the thickness of the thermoplastic sleeve is greater than the gap, so that the shear rod is in the middle of the first sleeve and the second sleeve, which increases the friction between the upper sleeve and the lower sleeve. When pouring the first pouring segment in step S2, the second sleeve can be prevented from falling off, and concrete slurry is prevented from entering from the gap between the first sleeve or the second sleeve and the shear rod; In step S1, the thermoplastic sleeve is firstly sleeved on the round rod portion of the shear rod, and then the shear rod is placed in the lower sleeve, and the lower sleeve is butt-jointed with the upper sleeve and then fixed by welding.

5. The construction method of the flexible immersed tube segment according to claim 1 is characterized in that: The shear-resistant structure is evenly distributed on the outer wall and the middle partition wall of the first-cast section and the later-cast section; The first sleeve and the second sleeve are arranged parallel to the axis of the immersed tube segment.

6. The construction method of the flexible immersed tube segment according to claim 1 is characterized in that: In step S1, the pipe segment is prefabricated using a skip bin method, the first-cast segment is an odd-numbered pipe segment, and the later-cast segment is an even-numbered pipe segment.

7. The construction method of a flexible immersed tube segment according to claim 1, characterized in that: Before the construction of the pipe segment, a sliding layer with a low friction coefficient is laid on the bottom formwork, and then the steel bars are tied and the concrete is poured; In step S2, during the overall tensioning process, the pipe segment slides relatively on the sliding layer, and the sliding layer can prevent the pipe segment from sticking to the bottom form concrete and reduce the friction resistance of the pipe segment when sliding.

8. The construction method of a flexible immersed tube segment according to claim 1, characterized in that: In step S1, the first cast segment and the later cast segment are both pre-buried with an embedded water stop during prefabrication; After the immersed tube segment is tensioned in step S2, a first water stop is installed between two adjacent segments, and a Gina water stop is installed at the joint of the segment at the end; Step S3: after the immersed tube segment settles stably, a second water stop is installed at the joint of the segment at the end; The embedded waterstop and the first waterstop enable the two adjacent pipe segments to form a double-channel flexible waterstop structure, and at the same time, the two adjacent pipe segments form a flexible connection; The Gina waterstop and the second waterstop enable the two adjacent immersed tube sections to form a double-channel flexible waterstop structure.

9. The construction method of a flexible immersed tube segment according to claim 1, characterized in that: In some embodiments of the present application, in step S1, when each of the pipe segments is prefabricated, prestressed steel strand cutting pipes are buried at both ends thereof, and a rope saw is arranged inside the prestressed steel strand cutting pipe. In step S3, after the settlement of the immersed tube segment is stable, the prestressed steel strands are cut off by the rope saw in a downward order from top to bottom, and the prestressed steel strand cutting pipe is sealed. After the prestressed steel strands are cut off, the immersed tube segment forms a flexible segment, which can adapt well to the rigid rock foundation and achieve a perfect fit of using softness to overcome hardness.

10. The construction method of a flexible immersed tube segment according to claim 1, characterized in that: In step S3, after the installation of the immersed tube is completed, the ballast water tank in the immersed tube segment is removed, and the pipe top loading construction is carried out at the same time. The ballast structure of the immersed tube segment is changed from temporary ballast to permanent ballast; after the settlement of the immersed tube segment is stable, the prestressed steel strands are cut off to form a flexible segment system.

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