A construction method for a flexible immersed tube segment

Abstract

The present invention relates to the technical field of underwater engineering, and in particular to a construction method for a flexible immersed tube segment. The immersed tube segment includes a plurality of tube segments, and the method comprises: S1 assembling a shear-resistant structure; S2 prefabricating the tube segments; S3 forming a rigid tube segment system; S4 converting the rigid tube segment system into a flexible tube segment system; the stress between the tube segments is transmitted and released through shear rods, which can achieve uniform stress transmission. The shear rods can conform to the deformation of two adjacent tube segments in any direction, and at the same time make the movement between the tube segments more uniform and gentle. The construction method of the present application is simple to operate, safe and efficient, breaks through the limitation of the rigid immersed tube structure in terms of length, can greatly extend the length of a single immersed tube segment, thereby reducing the number of times of prefabrication, floating and sinking of the immersed tube, effectively reducing the construction risk; at the same time, the flexible tube segment structure can better adapt to the differential settlement of the foundation, has better adaptability to the foundation, significantly improves the structural stability, and is more safe and durable.

Description

Technical Field

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

[0002] With the increasing maturity of the immersed tunnel technology for engineering, it is increasingly widely used in large 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 China.

[0003] At present, in immersed tunnels, steel shear keys are usually used between rigid precast immersed tube segments. Secondary installation is required after the concrete is poured. Limited by the narrow space inside the tube, the installation of steel shear keys is difficult and inefficient. Due to the limitations of the mechanical properties of concrete and steel shear keys, there are great limitations on the single-section precast length of rigid immersed tubes, and large deflections are likely to occur. In addition, steel shear keys are usually only distributed on the outer side of the tube segment and the position of the middle partition wall. After the tube segment is sunk and the prestressed tendon is cut off, the shear resistance between the tube segments only concentrates on the shear key position, and only the vertical shear stress can be eliminated. The stress release between the tube segments is not uniform enough, and the ability to adapt to differential settlement is weak, resulting in local stress concentration. Especially for rigid foundations on rock foundations, it will affect the full release of stress between structural segments and the ability to adapt to foundation deformation, and it is easy to cause problems such as 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 likely to occur between two adjacent tube segments, and the water stop belt between the two tube segments with larger gaps is easily torn, resulting in the failure of the water stop structure. Summary of the Invention

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

[0005] The present invention provides a construction method for a flexible immersed tube segment. The immersed tube segment includes a plurality of tube segments. A plurality of shear-resistant structures are evenly arranged between two adjacent tube segments. The shear-resistant structures are used to release the stress between the tube segments. The shear-resistant structure includes a shear rod and a sleeve assembly sleeved outside the shear rod. The sleeve assembly includes a first sleeve and a second sleeve that are butt-jointed in the horizontal direction. Both ends of the first sleeve and the second sleeve are expansion segments, and the expansion segments are formed by gradually expanding outward along their axial directions;

[0006] The construction method includes the following steps:

[0007] S1. Assemble the shear-resistant structure:

[0008] 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 butted against the second sleeve, respectively, wherein the fixing plates are coplanar with the end surface 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;

[0009] S2. Prefabrication of pipe segments:

[0010] 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;

[0011] The post-cast segment is prefabricated, the second sleeve is already located at the prefabricated 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; then the formwork is supported and concrete is poured; after the 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;

[0012] S3. Forming a rigid pipe joint system:

[0013] 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;

[0014] S4. Conversion of rigid pipe joint system to flexible pipe joint system:

[0015] The immersed tube segments of the above-mentioned rigid tube segment system are outfitted once and twice. When the installation conditions are met, the immersed tube segments after outfitting are floated to the installation position for sinking, docking and installation operations. After the settlement of the immersed tube segments 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 segments. 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 segments in any direction. The stress between the two tube segment segments 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 second cast segment.

[0016] The construction method of the flexible immersed tube segment of the present technical solution is simple in construction operation, safe and efficient, and solves the problem of stress concentration in the conversion of the immersed tube segment system from a technological perspective. The stress between the tube segment segments is released through the shear rod, which can achieve uniform stress transmission. The shear rod can adapt to the deformation of two adjacent tube segments in any direction, while ensuring the effectiveness of the shear structure, so that the movement between the tube segments is more uniform and smooth. 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 shrinks, the first sleeve and the second sleeve are subjected to horizontal stress, which limits the horizontal displacement of the shear rod, and the gap deformation between the two adjacent tube segments is uniform.

[0017] In some embodiments of the present application, the shear rod includes a round rod portion with equal diameter and a tensile portion located at both ends of the round rod portion, wherein the tensile portion is formed by the round rod portion gradually expanding outward along its axial direction; and the diameter gradually increases.

[0018] 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;

[0019] 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;

[0020] 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;

[0021] 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 each segment is relatively uniform, and avoid the waterstop structure between the pipe segments from being torn.

[0022] In some embodiments of the present application, the first sleeve includes an upper sleeve and a lower sleeve that are butt-jointed in the upper and lower directions;

[0023] 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;

[0024] The structures of the upper sleeve and the lower sleeve are mirror-symmetrical along the horizontal docking surface; after the upper sleeve and the lower sleeve are docked, the two first grooves and the two second grooves are respectively docked to form a first accommodation cavity for accommodating the shear rod;

[0025] 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 method.

[0026] In some embodiments of the present application, a thermoplastic sleeve is sleeved on the outer side of 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-poured 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;

[0027] In step S1, the thermoplastic sleeve is first 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 and the upper sleeve are welded and fixed after docking.

[0028] In some embodiments of the present application, the shear-resistant structures are uniformly distributed on the outer walls and the middle partition walls of the first-poured segment and the second-poured segment;

[0029] The first sleeve and the second sleeve are arranged parallel to the axis of the immersed tube segment.

[0030] In some embodiments of the present application, in step S2, the skip-joint method is used for prefabricating the tube segments. The first-poured segments are odd-numbered tube segments, and the second-poured segments are even-numbered tube segments, which improves the construction efficiency.

[0031] 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;

[0032] In step S3, 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.

[0033] In some embodiments of the present application, in step S2, a middle-buried waterstop is also pre-embedded in both the pre-poured segment and the post-poured segment during prefabrication.

[0034] After the tensioning of the immersed tube segment in step S3 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 located at the end.

[0035] In step S4, after the settlement of the immersed tube segment is stable, a second waterstop is installed at the joint of the tube segment located at the end.

[0036] The middle-buried waterstop and the first waterstop form a double-layer flexible waterstop structure between two adjacent tube segments, and at the same time, two adjacent tube segments form a flexible connection; the Gina waterstop and the second waterstop form a double-layer flexible waterstop structure between two adjacent immersed tube segments.

[0037] In some embodiments of the present application, in step S2, when each tube 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.

[0038] In some embodiments of the present application, in step S4, after the installation of the immersed tube is completed, the ballast water tank inside the immersed tube segment is removed, and at the same time, ballast 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.

[0039] 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 tube 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 tube segments in any direction, and at the same time, the movement between the tube segments is 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 segments contract, the first sleeve and the second sleeve are affected by the horizontal stress, and the displacement of the shear rods in the horizontal direction is limited, and the gap deformation between two adjacent tube segments is uniform.

[0040] The shear-resistant structure can prevent uneven settlement and deformation between the pipe sections, breaking through the limitation of the rigid immersed tube structure in terms of length. It can greatly extend the length of a single immersed tube section, thereby reducing the number of prefabrication, floating, and sinking operations of the immersed tubes, effectively reducing construction risks. At the same time, the flexible pipe section has a better adaptability to the foundation, can better adapt to the differential settlement of the foundation, significantly improve the structural stability, be more safe and durable, and ensure the construction and operation quality of the immersed tube tunnel.

[0041] There is no connection between adjacent two pipe sections except for the shear bars, the middle buried waterstop, and the first waterstop. The steel bars are discontinuous, forming a flexible connection between the pipe sections, which is conducive to the stress release between the pipe sections. Moreover, the middle buried waterstop and the first waterstop between adjacent two pipe sections form a double-channel flexible waterstop structure; the Gina waterstop and the second waterstop form a double-channel flexible waterstop structure between adjacent two immersed tube sections. At the same time, the joint of the immersed tube section is a flexible joint, which is conducive to the stress release between the two immersed tube sections. Brief Description of the Drawings

[0042] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation to the present invention. In the drawings:

[0043] Figure 1 It is a schematic structural diagram of an immersed tube section according to an embodiment of the present invention;

[0044] Figure 2 It is a schematic cross-sectional structural diagram of a shear-resistant structure according to an embodiment of the present invention;

[0045] Figure 3 It is a schematic structural diagram of a shear bar according to an embodiment of the present invention;

[0046] Figure 4 For the present invention Figure 2 Cross-sectional view of the B-B section;

[0047] Figure 5 It is a schematic structural diagram of a lower sleeve according to an embodiment of the present invention;

[0048] Figure 6 It is a schematic structural diagram of a shear bar according to another embodiment of the present invention;

[0049] Figure 7 It is a schematic cross-sectional structural diagram of a shear-resistant structure according to another embodiment of the present invention;

[0050] Figure 8 For the present invention Figure 2 Cross-sectional view of the A-A section;

[0051] Figure 9Schematic diagram of the end face structure of the pre-cast segment of the present invention;

[0052] Figure 10 Schematic diagram of the positional relationship between the prestressed pipe and the prestressed steel strand cutting pipe of the present invention;

[0053] Figure 11 Schematic diagram of the structure of the left end face of the E1 segment of the present invention;

[0054] Figure 12 Schematic diagram of the end face structure of the post-cast segment of the present invention;

[0055] Figure 13 Schematic diagram of the structure of the right end face of the E8 segment of the embodiment of the present invention.

[0056] In the figure, 10 is the immersed tube segment; 11 is the pre-cast segment; 111 is the first pipe joint steel shear key; 12 is the post-cast segment; 122 is the second pipe joint steel shear key; 20 is the shear resistance structure; 21 is the shear rod; 211 is the round rod part; 212 is the tensile part; 22 is the first sleeve; 221 is the first accommodation cavity; 2211 is the first groove; 2212 is the second groove; 222 is the upper sleeve; 223 is the lower sleeve; 2231 is the straight part; 2232 is the enlarged part; 23 is the second sleeve; 231 is the second accommodation cavity; 24 is the expansion section; 241 is the enlarged cavity; 25 is the thermoplastic sleeve; 26 is the reinforcing plate; 27 is the fixing plate; 28 is the reinforcing rib; 30 is the prestressed duct; 31 is the prestressed steel strand cutting pipe. Detailed implementation manners

[0057] Next, the technical solutions in the embodiments will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0058] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "transverse", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is 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 thus cannot be understood as a limitation of the present invention.

[0059] 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.

[0060] 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.

[0061] This embodiment provides a construction method for a flexible immersed tube segment. Figure 1 As 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;

[0062] 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;

[0063] 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.

[0064] 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;

[0065] 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 ;

[0066] The diameter of the round rod portion 211 is smaller than the inner diameters of the first receiving cavity 221 and the second receiving cavity 231. A part of the round rod portion 211 extends into the enlarged cavity 241. The minimum diameter of the tensile part 212 is larger than the inner diameter of the narrowest part of the enlarged cavity 241. When a horizontal displacement occurs between two adjacent pipe joint segments, the first sleeve 22 or the second sleeve 23 moves synchronously with the pipe joint segment. When the narrowest part of the enlarged cavity 241 of the first sleeve 22 or the second sleeve 23 moves to contact the smallest diameter part of the tensile part 212 of the shear rod 21, the first sleeve 22 or the second sleeve 23 stops moving, which can limit the occurrence of a small horizontal displacement between two adjacent pipe joint segments, make the gaps between adjacent pipe joint segments evenly distributed, and avoid the phenomenon that the gap between two of the pipe joint segments is too large.

[0067] As Figure 4 shown, the first sleeve 22 of this embodiment includes an upper sleeve 222 and a lower sleeve 223 that are butted in the up-down direction;

[0068] As Figure 5 shown, the lower sleeve 223 includes a straight part 2231 and an enlarged part 2232. The side elevation shape of the straight part 2231 is rectangular, and a semi-circular first groove 2211 corresponding to the round rod portion 211 is opened on its upper end surface. The side elevation shape of the enlarged part 2232 is rectangular, and the front elevation shape is trapezoidal. A second groove 2212 corresponding to the shape of the tensile part 212 is opened on the upper end surface of the enlarged part 2232;

[0069] The structures of the upper sleeve 222 and the lower sleeve 223 are mirror-symmetrical along the horizontal butting surface; after the upper sleeve 222 and the lower sleeve 223 are butted, the upper and lower first grooves 2211 and the two second grooves 2212 form the first receiving cavity 221 for accommodating the left side of the shear rod 21;

[0070] The structure of the second sleeve 23 is symmetrical to that of the first sleeve 22, and its structure will not be elaborated here.

[0071] Furthermore, a thermoplastic sleeve 25 is sleeved outside the round rod portion 211. The thermoplastic sleeve 25 is used to fill the gap between the round rod portion 211 and the first receiving cavity 221 and the second receiving cavity 231, and the thickness of the thermoplastic sleeve 25 is larger than this gap, so that the shear rod 21 is in the central position of the first sleeve 22 and the second sleeve 23, increasing the friction with the upper sleeve 222 and the lower sleeve 223, sealing the butting part of the first sleeve or the second sleeve, and preventing the concrete slurry from entering through the gap between the first sleeve or the second sleeve and the shear rod.

[0072] As another embodiment of the present application, the shear bar 21 includes a circular rod portion 211 with a constant diameter and tensile portions 212 located at both ends of the circular rod portion 211. Different from the previous embodiment, in this embodiment, the tensile portion 212 is a cylindrical structure with a diameter larger than that of the circular rod portion 211. The tensile portion 212 is perpendicular to the axis of the circular rod portion 211, and there are at least two tensile portions 212 at each end of the circular rod portion 211. As Figure 6 shown, there are a total of four tensile portions 212 at both ends of the circular rod portion 211. When horizontal shear forces act between adjacent pipe joint segments, the horizontal shear forces can be dispersed to the four tensile portions 212 at both ends, so that the stress is evenly dispersed on the shear bar 21, which can limit the occurrence of uniform horizontal displacement between adjacent two pipe joint segments, make the gaps between adjacent pipe joint segments evenly distributed, and avoid the phenomenon that the gap between two of the pipe joint segments is too large; it can also avoid the situation where when the stress is too large, there is only one tensile portion 212 at the end, and the stress is concentrated on this tensile portion 212, resulting in the structural failure of the tensile portion 212.

[0073] As Figure 7 shown, the first sleeve 22 and the second sleeve 23 in this embodiment are cylindrical structures or cuboid structures with a constant diameter and have no expansion section. In order to increase the connection strength between the first sleeve 22 and the second sleeve 23 and the concrete of the pipe joint segment and prevent the first sleeve 22 from being pulled out from the pre-cast segment or the second sleeve 23 from the post-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, and improve the firmness of the first sleeve 22 in the pre-cast segment and the second sleeve 23 in the post-cast segment.

[0074] The tail end of the first accommodation cavity 221 of the first sleeve 22 is two enlarged cavities 241, and the two enlarged cavities 241 respectively accommodate the two tensile portions 212 on the left side of the shear bar 21. The tail end of the second accommodation cavity 231 of the second sleeve 23 is also two enlarged cavities 241, and the two enlarged cavities 241 respectively accommodate the two tensile portions 212 on the right side of the shear bar 21; the enlarged cavity 241 in this embodiment is a cylindrical cavity with a diameter larger than that of the tensile portion 212;

[0075] The first sleeve 22 includes an upper sleeve 222 and a lower sleeve 223 that are butt-jointed in the up-down direction. The upper end surface of the lower sleeve 223 is provided with a semi-circular first groove 2211 corresponding to the circular rod portion 211 and two semi-circular 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-joint surface; after the upper sleeve 222 and the lower sleeve 223 are butt-jointed, the two upper and lower first grooves 2211 and the two second grooves 2212 form the first accommodation cavity 221 for accommodating the left side of the shear bar 21;

[0076] 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.

[0077] 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.

[0078] The construction method of the flexible immersed tube segment includes the following steps:

[0079] 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;

[0080] 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 8 As 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;

[0081] Repeat the above operation to assemble the remaining shear-resistant structures 20;

[0082] 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, during sequential construction, 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.

[0083] 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 Figures 9 - 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;

[0084] 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 9 As shown, it is also necessary to embed steel sealing door embedded parts (not shown in the figure), Gina waterstop and second waterstop embedded parts (not shown in the figure) for water stopping between pipe sections, the second embedded part is a larger Ω waterstop, and then the formwork is supported and concrete is poured;

[0085] After the precast segment 11 is precast, the subsequent cast segments 12, namely E2, E4, E6, and E8, are precast. At this time, the second sleeve 23 is already located at the precast position of the subsequent cast segment 12. Figure 12As shown in the figure. Similar to the precast 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 installed. The prestressed ducts 30 in the precast segment 11 and the prestressed ducts 30 in the postcast segment 12 form a longitudinally continuous duct; a middle waterstop and a first waterstop embedded part are embedded; after the postcast segment 12 is poured, the first sleeve 22 of the shear resistance structure 20 is located in the precast segment 11, the left half part of the shear rod 21 is located in the first sleeve 22, the second sleeve is located in the postcast segment 12, and the right half part of the shear rod 21 is located in the second sleeve 23;

[0086] The shear resistance structure only needs to fix the fixing plate 27 on the formwork of the precast segment 11 to complete the installation. During the prefabrication of the postcast segment 12, there is no need to fix the shear resistance structure, which simplifies the construction steps and improves the construction efficiency;

[0087] Similar to the precast segment E1, the right end face of the postcast segment E8 is the pipe joint end face when docking with the next adjacent immersed tube segment. There is no need to fix the shear resistance structure 20. It is necessary to 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 two immersed tube segments. As Figure 13 shown in the figure, it is also necessary to embed a steel sealing door embedded part (not shown in the figure), and a Gina waterstop and a second waterstop embedded part (not shown in the figure), and then formwork erection and concrete pouring operations are carried out;

[0088] Furthermore, the first sleeve 22 and the second sleeve 23 are arranged parallel to the axis of the immersed tube segment 10. Therefore, the shear rod 21 is also parallel to the axis of the immersed tube segment 10. The shear rod 21 can bear stresses in any direction between the precast segment 11 and the postcast segment 12 and deform in any direction.

[0089] After all the precast segments 11 and postcast segments 12 of the shear rod 21 are prefabricated and the concrete strength reaches the expected strength, the prestressed steel strands are tensioned from the left end face of the E1 segment and the right end face of the E8 segment, and the tensioning is carried out in the order of from the middle to both sides and from bottom to top. During the tensioning, the precast segment 11 and the postcast segment 12 slide relative to each other 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 segment is in a compressed state, and the immersed tube segment 10 forms a temporary rigid pipe segment system;

[0090] 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 waterstop between segments, the Gina waterstop 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 winched and moved to the outfitting area for secondary outfitting; after the secondary outfitting operation is completed, the immersed tube segment 10 is winched and moved to the storage area; when the gravel bed is leveled and the installation conditions are met, the immersed tube segment 10 is floated to the installation position by an installation vessel for sinking, docking, and installation;

[0091] After the installation of the immersed tube segment 10 is completed, the side locking backfill and the general backfill on the top of the tube 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 crushed 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 crushed stone ballast;

[0092] 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 structure are installed, grouting is carried out between the steel shear keys, the concrete shear key of the horizontal shear structure is poured, and the second waterstop between the pipe segments, that is, the larger-sized Ω waterstop, is installed to form a flexible pipe joint.

[0093] The embedded waterstop and the first waterstop form a double-layer flexible waterstop 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 waterstop and the second waterstop form a double-layer flexible waterstop structure between two adjacent immersed tube segments 10.

[0094] 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 wire saw in the prestressed steel strand cutting tube 31 is used to cut the prestressed steel strands, 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, and the stress between the precast segment 11 and the postcast segment 12 is completely released through the shear rods 21, which can well adapt to the rocky rigid foundation and achieve a perfect fit of using flexibility to overcome rigidity.

[0095] 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 minimum diameter part of the tensile part 212 of the shear rod 21, the first sleeve 22 or the second sleeve 23 is limited 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.

[0096] 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, resulting in tearing of 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 limitation of the rigid immersed tube structure in terms of length, can greatly extend the length of a single immersed tube, thereby reducing the number of precast, floating and sinking operations of the immersed tube, and effectively reducing the construction risk.

[0097] Finally, it should be noted that the 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 embodiments, reference can be made to each other.

[0098] The above embodiments are only used to illustrate the technical solutions of the present invention rather than 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 modifications can still be made to the specific implementation manners of the present invention or equivalent replacements can be made to 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 by: The immersed tube segment includes a plurality of tube segments. A plurality of shear structures are evenly arranged between two adjacent tube segments. The shear structures are used to release the stress between the tube segments. The shear structure includes a shear rod and a sleeve assembly sleeved outside the shear rod. The sleeve assembly includes a first sleeve and a second sleeve docked in the horizontal direction. Both ends of the first sleeve and the second sleeve are expansion segments, and the expansion segments are formed to gradually expand outward along their axial directions; The construction method includes the following steps: S1. Assemble the 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 on the docking end face with the second sleeve respectively. 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 structure; repeat step S1 to complete the assembly of the remaining shear structures; S2. Prefabricate the tube segments: Prefabricate the tube segments in the site area. The previously prefabricated tube segments are the first-cast segments, and the later prefabricated tube segments are the second-cast segments. When prefabricating the first-cast segments, bind the steel bars, embed the prestressed ducts, erect the formwork, and fix the fixing plates on the end formwork so that the first sleeve of the shear structure is located in the first-cast segment, and then pour the concrete of the first-cast segment. The second sleeve is the free end; When prefabricating the second-cast segments, the second sleeve is already located at the prefabrication position of the second-cast segments. Bind the steel bars, embed the prestressed ducts, and make the prestressed ducts in the first-cast segments and the prestressed ducts in the second-cast segments form a pipeline that penetrates in the length direction, and then erect the formwork and pour the concrete; after prefabrication, the shear rod is located between two adjacent first-cast segments and the second-cast segments, and the prestressed steel strands in the prestressed ducts connect the plurality of tube segments to form the overall immersed tube segment; S3. Form a rigid tube segment system: After all the tube segments are prefabricated and the concrete strength reaches the expected strength, tension the two ends of the prestressed steel strands located at both ends of the immersed tube segment. After the tensioning is completed, perform grouting and anchor sealing operations. At this time, each tube segment is in a compressed state, and the immersed tube segment forms a temporary rigid tube segment system; S4. Convert the rigid tube segment system to a flexible tube segment system: Perform primary outfitting and secondary outfitting on the immersed tube segment of the above rigid tube segment system; When the installation conditions are met, float the outfitted immersed tube segment to the installation position and perform sinking, docking, and installation operations. After the immersed tube segment sinks stably, install the horizontal shear structure and the vertical shear structure between the immersed tube segments, and cut the prestressed steel strands between two adjacent tube segments. The immersed tube segment is converted from a rigid tube segment system to a flexible tube segment system. The shear rod can conform to the deformation of the two tube segments in any direction, and the stress between the two tube segments is completely released through the shear rod. The expansion segments prevent the first sleeve from being pulled out of the first-cast segment or the second sleeve from being pulled out of the second-cast segment; The shear bar includes a circular rod portion with a constant 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; A first accommodation cavity for accommodating one side structure of the shear bar is provided in the first sleeve, and a second accommodation cavity for accommodating the other side structure of the shear bar is provided in the second sleeve; The tail ends of the first accommodation cavity and the second accommodation cavity are enlarged cavities for accommodating the tensile portions of the shear bar; The diameter of the circular rod portion is smaller than the inner diameters of the first accommodation cavity and the second accommodation cavity. A part of the circular rod portion extends into the enlarged cavity, and the minimum diameter of the tensile portion is greater than the inner diameter of the narrowest part of the enlarged cavity; In step S4, when horizontal displacement occurs between two adjacent pipe joint segments, the first sleeve or the second sleeve moves synchronously with the pipe joint 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 bar, the first sleeve or the second sleeve stops moving, which can limit the horizontal displacement between two adjacent pipe joint segments, ensure relatively uniform displacement between each pipe joint segment, and at the same time prevent the water stop structure between the pipe joint segments from being torn.

2. The construction method of the flexible immersed tube section according to claim 1, characterized in that 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 shape 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 shape of the enlarged portion is rectangular, and the front elevation shape 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 bar; In step S1, one side of the shear bar 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 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 bar in the same way.

3. The construction method of the flexible immersed tube section according to claim 1, characterized in that, A thermoplastic sleeve is sleeved outside the circular rod portion. The thermoplastic sleeve is used to fill the gap between the circular rod portion and the first accommodation cavity and the second accommodation cavity, and the thickness of the thermoplastic sleeve is greater than the gap, so that the shear bar 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-poured segment, it can prevent the second sleeve from falling off and at the same time prevent the concrete slurry from entering through the gap between the first sleeve or the second sleeve and the shear bar; In step S1, first, the thermoplastic sleeve is sleeved on the circular rod portion of the shear bar, and then the shear bar is placed in the lower sleeve. After the lower sleeve and the upper sleeve are butt-jointed, they are welded and fixed.

4. The construction method of the flexible immersed tube section according to claim 1, characterized in that, The shear structures are evenly distributed on the outer walls and middle partition walls of the first-poured segment and the second-poured segment; The first sleeve and the second sleeve are arranged parallel to the axis of the immersed tube segment.

5. The construction method of the flexible immersed tube section according to claim 1, characterized in that In step S2, the segment casting method is used for precasting the tube segments. The first-cast segments are odd-numbered tube segments, and the post-cast segments are even-numbered tube segments.

6. The construction method of the flexible immersed tube section according to claim 1, characterized in that, Before the construction of the tube segment, a sliding layer with a small friction coefficient is laid on the bottom formwork, and then the steel bars are tied and the concrete is poured. In step S3, during the overall tensioning process, the tube segments slide relative to each other on the sliding layer. The sliding layer can not only prevent the tube segments from sticking to the bottom formwork concrete, but also reduce the frictional resistance when the tube segments slide.

7. The construction method of the flexible immersed tube section according to claim 1, characterized in that, In step S2, a middle embedded waterstop is also embedded in both the first-cast segments and the post-cast segments during precasting. After the tensioning of the immersed tube segment in step S3 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 S4, 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-layer flexible waterstop structure between two adjacent tube segments, and at the same time, two adjacent tube segments form a flexible connection. The Gina waterstop and the second waterstop form a double-layer flexible waterstop structure between two adjacent immersed tube segments.

8. The construction method of the flexible immersed tube segment according to claim 1, characterized in that, In step S2, when each tube segment is precast, prestressed steel strand cutting tubes are embedded at both ends. A wire saw is arranged inside the prestressed steel strand cutting tube. 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 tubes 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.

9. The construction method of the flexible immersed tube section according to claim 1, characterized in that, In step S4, after the immersed tube is installed, the ballast water tanks inside the immersed tube segment are removed, and at the same time, construction of loading on the top of the tube is carried out. 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.

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