A construction method of a submarine immersed tube tunnel pipe joint

Abstract

The application relates to a construction method of a submarine immersed tube tunnel pipe section, which comprises the following steps: performing slope excavation on a seabed to form a foundation trench; constructing high-pressure rotary jet piles at the bottom of the foundation trench and hoisting the immersed tube at the bottom of the foundation trench; wherein at least part of the high-pressure rotary jet piles are supported at the bottom of the immersed tube; constructing rigid piles at the bottom of the foundation trench so that the rigid piles are supported at opposite two side walls of the immersed tube; and backfilling and compacting the foundation trench to complete the construction of the immersed tube. The rigid piles are punched into the opposite two side walls of the immersed tube to protect the immersed tube from overturning damage, the ground soil around the rigid piles is in transverse extrusion, the high-pressure rotary jet piles and the rigid piles jointly compact the foundation, the rigid piles and the high-pressure rotary jet piles jointly replace the ground soil and jointly bear the load, the construction is convenient, the cost is low, the bearing capacity is high, the anti-seismic performance is good, the anti-floating capacity is good and the like, and the method can effectively improve the uneven settlement of the immersed tube.

Description

Technical Field

[0001] This invention relates to the field of submarine immersed tunnel segment construction, and particularly to a construction method for submarine immersed tunnel segments. Background Technology

[0002] The development of immersed tunnels is becoming increasingly rapid. In recent years, more and more immersed tunnel projects have been completed or are under construction in China, such as the Yongjiang Immersed Tunnel and the Shenzhen-Zhongshan Bridge. These projects inevitably pass through unfavorable strata, such as silt, clay, and mud. Under various loads, especially extreme loads such as earthquakes, submarine geological movements, tides, and tsunamis, uneven deformation of the foundation and heave of the tunnel structure can occur, affecting its use or even causing damage. Therefore, it is of great significance to consider foundation treatment in soft soil strata to reduce uneven settlement.

[0003] In related technologies, traditional foundation treatment methods such as replacement and consolidation drainage are not applicable in aquatic environments. Furthermore, the tolerance for uneven settlement of immersed tunnel segments is relatively small, which cannot effectively improve the problem of uneven settlement of immersed tunnel segments. Summary of the Invention

[0004] This invention provides a construction method for a submerged tunnel segment, which solves the problem that traditional foundation treatment methods in related technologies cannot effectively improve the uneven settlement of submerged tunnel segments.

[0005] This invention provides a construction method for a subsea immersed tunnel segment, comprising the following steps:

[0006] The seabed is sloped and excavated to form a foundation trench;

[0007] High-pressure jet grouting piles are constructed at the bottom of the foundation trench, and a driven pipe is suspended at the bottom of the foundation trench; wherein at least a portion of the high-pressure jet grouting piles are supported at the bottom of the driven pipe.

[0008] Rigid piles are constructed at the bottom of the foundation trench to support the opposite side walls of the driven pipe.

[0009] The trench was backfilled and compacted to complete the construction of the immersed tube.

[0010] In some embodiments, the construction of high-pressure jet grouting piles at the bottom of the foundation trench and the placement of driven pipes at the bottom of the foundation trench include:

[0011] High-pressure jet grouting piles are constructed at the bottom of the foundation trench;

[0012] Enlarge the bottom end of the high-pressure jet grouting pile;

[0013] The submerged pipe is suspended at the bottom of the foundation trench.

[0014] In some embodiments, the step of suspending the submerged pipe at the bottom of the foundation trench includes:

[0015] Lay the first crushed stone cushion layer at the bottom of the foundation trench and compact and level the first crushed stone cushion layer.

[0016] The submerged tube is hoisted and placed on the surface of the first crushed stone cushion layer.

[0017] In some embodiments, the construction of rigid piles at the bottom of the foundation trench, such that the rigid piles support the opposite side walls of the driven tube, includes:

[0018] A second crushed stone cushion layer is laid at the bottom of the foundation trench and compacted and leveled; the top surface of the second crushed stone cushion layer is lower than the top surface of the submerged pipe.

[0019] Rigid piles were constructed on the top surface of the second crushed stone cushion layer.

[0020] In some embodiments, the construction of rigid piles at the bottom of the trench, with the rigid piles supported by the opposite side walls of the driven tube, includes:

[0021] Steel reinforcement assemblies are built on the pre-embedded steel bars on both sides of the immersed tube, so that the pre-embedded steel bars and steel reinforcement assemblies together form a steel cage; wherein, the pre-embedded steel bars are at least partially embedded in the immersed tube.

[0022] Concrete is poured inside the steel cage to form a load transfer structure on the opposite side walls of the immersed tube; the bottom of the load transfer structure is connected to the top of the corresponding rigid pile.

[0023] In some embodiments, before the pre-embedded reinforcing bars on both opposite side walls of the immersed tube are assembled into reinforcing steel assemblies, so that the pre-embedded reinforcing bars and the reinforcing steel assemblies together form a reinforcing cage, the following steps are included:

[0024] A pile cap is constructed at the top of the rigid pile; wherein the cross-section of the pile cap is larger than the bottom area of ​​the load transfer structure.

[0025] In some embodiments, the pre-embedded reinforcing bars on the opposite side walls of the immersed tube are all assembled into reinforcing steel assemblies, so that the pre-embedded reinforcing bars and the reinforcing steel assemblies together form a reinforcing cage, including:

[0026] Extend the length of the embedded steel bar by screwing an extension bar into the end of the embedded steel bar.

[0027] Longitudinal steel bars are used to connect multiple extended steel bars that are spaced apart along the length of the immersed tube into a whole, thus completing the construction of the steel reinforcement assembly.

[0028] In some embodiments, the process prior to sloping and excavating the seabed to form the trench includes:

[0029] Precast immersed tunnel sections are carried out in the dry dock;

[0030] Pre-embedded reinforcing bars are installed in the opposite side walls of the immersed tube; wherein at least part of the pre-embedded reinforcing bars are located outside the immersed tube.

[0031] In some embodiments, after embedding pre-embedded reinforcing bars in the opposite side walls of the immersed tube, the process includes:

[0032] The embedded steel bars are treated with anti-corrosion measures.

[0033] In some embodiments, after embedding pre-embedded reinforcing bars in the opposite side walls of the immersed tube, the process includes:

[0034] Weld a steel sleeve to the end of the pre-embedded steel bar and perform anti-corrosion treatment on the steel sleeve.

[0035] The beneficial effects of the technical solution provided by this invention include: rigid piles are driven into the opposite sides of the immersed tube, protecting the immersed tube from overturning damage; the foundation soil around the rigid piles is under lateral compressive pressure, and together with the high-pressure jet grouting piles, it plays a role in compacting the foundation; at the same time, both the rigid piles and the high-pressure jet grouting piles have the effect of replacing the foundation soil, sharing the load with the foundation soil and coordinating the force, which has the advantages of low cost, convenient construction, high bearing capacity, good seismic performance, and good anti-buoyancy ability, effectively improving the problem of uneven settlement of the immersed tube. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 A schematic flowchart illustrating the construction method for a subsea immersed tunnel segment provided in an embodiment of the present invention;

[0038] Figure 2 This is a cross-sectional structural diagram of immersed tube construction provided in an embodiment of the present invention;

[0039] Figure 3 This is an enlarged structural schematic diagram of the load transfer structure provided in an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the soil anti-buoyancy mechanism provided in an embodiment of the present invention;

[0041] Figure 5 for Figure 2 A schematic diagram of the side cross-sectional structure;

[0042] Figure 6 This is a top view of the arrangement of high-pressure jet grouting piles and rigid piles provided in an embodiment of the present invention.

[0043] In the diagram: 1. Seabed; 2. Foundation trench; 3. High-pressure jet grouting pile; 4. Sinking pipe; 41. Embedded reinforcing bar; 42. Reinforcing bar sleeve; 43. Structural reinforcing bar; 5. Rigid pile; 6. First crushed stone cushion layer; 7. Second crushed stone cushion layer; 8. Reinforcing bar assembly; 81. Extension reinforcing bar; 82. Longitudinal reinforcing bar; 9. Load transfer structure; 10. Foundation; 11. Seawater; 12. Anti-floating soil wedge. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] This invention provides a construction method for a submerged tunnel segment, which solves the problem that traditional foundation treatment methods in related technologies cannot effectively improve the uneven settlement of submerged tunnel segments.

[0046] like Figure 1 As shown in the figure, this embodiment of the invention provides a construction method for a subsea immersed tunnel segment, which includes the following steps:

[0047] Step S100: Excavate the seabed 1 with slope to form the foundation trench 2;

[0048] Step S200: Construct high-pressure jet grouting piles 3 at the bottom of the foundation trench 2, and hoist the driven pipe 4 at the bottom of the foundation trench 2; wherein, at least a portion of the high-pressure jet grouting piles 3 are supported at the bottom of the driven pipe 4;

[0049] Step S300: Construct rigid piles 5 at the bottom of the foundation trench 2, so that the rigid piles 5 are supported on the opposite side walls of the immersed tube 4;

[0050] Step S400: Backfill and compact the foundation trench 2 to complete the construction of the immersed tube 4.

[0051] Among them, such as Figure 2 As shown, seawater 11 is above seabed 1. The top surface of seabed 1 is excavated by slope to form trench 2. A certain number of high-pressure jet grouting piles 3 are constructed on the inner bottom wall of trench 2, and a reserved area is planned for the subsequent construction of rigid piles 5. The immersed tube 4 is hoisted and placed at the bottom of trench 2. Then, the rigid piles 5 are constructed in the reserved area on the inner bottom wall of trench 2, so that the rigid piles 5 are supported on the opposite side walls of the immersed tube 4.

[0052] Specifically, rigid piles 5 are driven into the opposite sides of the immersed tube 4 to protect the immersed tube 4 from overturning damage. This allows the foundation soil around the rigid piles 5 to be under lateral compressive stress, which, together with the high-pressure jet grouting piles 3, compacts the foundation. At the same time, both the rigid piles 5 and the high-pressure jet grouting piles 3 have the function of replacing the foundation soil, sharing the load with the foundation soil and working together to bear the force. This has the advantages of low cost, convenient construction, high bearing capacity, good seismic performance, and good anti-buoyancy ability, effectively improving the problem of uneven settlement of the immersed tube 4.

[0053] In some embodiments, such as Figure 2 As shown, step S200 may include the following steps:

[0054] Step S210: Construct high-pressure jet grouting piles 3 at the bottom of the foundation trench 2;

[0055] Step S220: Enlarge the bottom end of the high-pressure jet grouting pile 3;

[0056] Step S230: Lower the submerged pipe 4 into the bottom of the foundation trench 2.

[0057] Among them, the enlarged lower pile end of the high-pressure jet grouting pile 3 can suppress pile uplift and protect the structure from overturning damage. It has the advantages of low cost, convenient construction, high bearing capacity, good seismic performance, and good anti-buoyancy ability, and has broad prospects in the application of immersed tunnels.

[0058] Furthermore, step S230 may include the following steps:

[0059] Step S231: Lay the first crushed stone cushion layer 6 at the bottom of the foundation trench 2, and compact and level the first crushed stone cushion layer 6.

[0060] Step S232: The submerged tube 4 is suspended and placed on the surface of the first crushed stone cushion layer 6.

[0061] The first crushed stone cushion layer 6 can protect the upper end of the high-pressure jet grouting pile 3, and also provide good support for the driven pipe 4, thus improving the problem of uneven settlement of the driven pipe 4.

[0062] In some embodiments, such as Figure 2 As shown, step S300 may include the following steps:

[0063] Step S310: Lay a second crushed stone cushion layer 7 at the bottom of the foundation trench 2 and compact and level the second crushed stone cushion layer 7; wherein, the top surface height of the second crushed stone cushion layer 7 is lower than the top surface height of the submerged pipe 4.

[0064] Step S320: Construct rigid piles 5 on the top surface of the second crushed stone cushion layer 7.

[0065] The second crushed stone cushion layer 7 can ensure the construction of the rigid pile 5, and the upper end of the rigid pile 5 can compact the second crushed stone cushion layer 7; it shares the load with the second crushed stone cushion layer 7 and works together to bear the force.

[0066] In some embodiments, such as Figure 2 and Figure 3 As shown, after step S300, the following steps may be included:

[0067] Step S330: Build steel reinforcement assemblies 8 on the pre-embedded steel bars 41 on both sides of the immersed tube 4, so that the pre-embedded steel bars 41 and the steel reinforcement assemblies 8 together form a steel cage; wherein, the pre-embedded steel bars 41 are at least partially embedded in the immersed tube 4.

[0068] Step S340: Pour concrete into the steel cage to form a load transfer structure 9 on the opposite side walls of the sinking tube 4; wherein the bottom of the load transfer structure 9 is connected to the top of the corresponding rigid pile 5 through a pile cap 10.

[0069] Among them, the load transfer structure 9 increases the overall strength of the immersed tube 4 on the one hand, and increases the area of ​​the traditional anti-buoyancy soil wedge 12 on the other hand, thereby increasing the soil pressure that the immersed tube 4 needs to overcome when it is pulled up.

[0070] Among them, such as Figure 2 As shown, prior to step S330, the following steps may be included:

[0071] Step S320: Construct a pile cap 10 at the top of the rigid pile 5; wherein the cross-section of the pile cap 10 is larger than the bottom area of ​​the load transfer structure 9.

[0072] Among them, the pile cap 10 can ensure the smooth construction of the load transfer structure 9, and at the same time, it can also ensure that the upper load of the load transfer structure 9 is transferred to the pile cap 10, and then smoothly transferred to the rigid pile 5, and finally transferred to the foundation soil for dispersion.

[0073] In some embodiments, such as Figure 3 As shown, step S330 may include the following steps:

[0074] Step S331: Screw the extension bar 81 into the end of the embedded bar 41 to extend the length of the embedded bar 41;

[0075] Step S332: Use longitudinal steel bars 82 to connect multiple extended steel bars 81 that are spaced apart along the length of the immersed tube 4 into a whole, and complete the construction of the steel bar assembly 8.

[0076] For example, along the height direction of the immersed tube 4, at least three pre-embedded steel bars 41 are embedded at intervals on the side wall of the immersed tube 4. The pre-embedded steel bars 41 are arranged in a J-shape, with one bent end hooked into the outer wall of the structural steel bar 43 embedded in the immersed tube 4 (the structural steel bar 43 extends along the length direction of the immersed tube 4), and the other end exposed outside the immersed tube 4, which facilitates the subsequent construction of the steel cage and reduces underwater construction steps. The extension steel bars 81 can also be arranged in a J-shape, with the vertical end of the extension steel bar 81 tied to the other end of the pre-embedded steel bar 41, and the bent end of the extension steel bar 81 connected by extension steel bars 81, thereby completing the construction of the steel cage.

[0077] In some embodiments, the following steps may be included before step S100:

[0078] Step S000: Prefabricate the immersed tube 4 in the dry dock;

[0079] Step S010: Embedded steel bars 41 are installed in the opposite side walls of the immersed tube 4; wherein, at least part of the embedded steel bars 41 are located outside the immersed tube 4.

[0080] Among them, the immersed tube 4 can be prefabricated in the dry dock, and pre-embedded steel bars 41 are embedded on both sides of the immersed tube 4. The steel cage is built on the ground in advance, reducing the underwater construction steps and reducing the difficulty of underwater construction.

[0081] Furthermore, after step S010, the following steps may be included:

[0082] Step S020: Perform anti-corrosion treatment on the pre-embedded steel bar 41.

[0083] Furthermore, after step S020, the following steps may be included:

[0084] Step S030: Weld a steel sleeve 42 to the end of the pre-embedded steel bar 41 and perform anti-corrosion treatment on the steel sleeve 42.

[0085] The painting of the pre-embedded steel bars 41 and the steel bar sleeve 42 is a corrosion protection treatment, which can ensure the construction quality of the immersed tube 4. At the same time, the steel bar sleeve 42 can facilitate the underwater construction of the extended steel bar 81.

[0086] In the embodiments mentioned above, such as Figure 2 , Figure 5 and Figure 6As shown, for example, the replacement rate of the high-pressure jet grouting piles 3 at the bottom of the immersed tube 4 is 30%, and a group pile arrangement is adopted in a square distribution. The rigid piles 5 arranged under the load transfer structure 9 are staggered from the high-pressure jet grouting piles 3 on the lower side of the immersed tube 4. According to the construction sequence from bottom to top, the high-pressure jet grouting piles 3 are arranged in sequence, the first crushed stone cushion layer 6 is laid, the immersed tube 4 is hoisted and sunk, the second crushed stone cushion layer 7 is backfilled and compacted, the rigid piles 5 are driven in, the foundation 10 is constructed, the load transfer structure 9 is poured, and the foundation trench 2 is backfilled and compacted. The immersed tube 4 can take the standard tube section of the Hong Kong-Zhuhai-Macau Bridge immersed tunnel as an example, with a length of 180m, a width of 37.95m, and a height of 11.4m. The width and height of the inclined sections on both sides of the immersed tube 4 can be 3.62m.

[0087] like Figure 3 As shown, the immersed tube 4 can be pre-embedded with reinforcing bars 41 during the prefabrication of tube sections in the dry dock. Their arrangement needs to be completed before the pouring of the wall and top slab of the immersed tube 4. One end needs to form an effective lap with the structural reinforcing bars 43 of the immersed tube 4, and the reserved welding length needs to meet the relevant design requirements for reinforcing bar laps. The other end needs to pass through the combined formwork of the bottom slab, wall, and other sections of the immersed tube 4 to form a reserved section. Before the immersed tube 4 leaves the dock, the exposed pre-embedded reinforcing bars 41 are treated with a coating for corrosion protection. The strength of the pre-embedded reinforcing bars 41 can be 500MPa, and the spacing is the same as the spacing of the structural reinforcing bars 43 in the wall. The total arrangement height from top to bottom on the side of the immersed tube 4 can be 3.62m. The conical end of the reinforcing bar sleeve 42 needs to be welded to the pre-embedded reinforcing bars 41 during the prefabrication stage. The inner diameter of the cylindrical end of the reinforcing bar sleeve 42 is the same as the diameter of the extended reinforcing bar 81. The load transfer structure 9 is cast-in-place reinforced concrete. The cross-sectional shape of the load transfer structure 9 can be a combination of an isosceles triangle with a vertex angle of 135 degrees and a leg length of 5.12m and a rectangle with a length of 5.12m and a width of 2.0m. The reinforcing bars include embedded reinforcing bars 41, extension reinforcing bars 81, and longitudinal reinforcing bars 82. The extension reinforcing bars 81 should have the same strength as the embedded reinforcing bars 41. One end of the extension reinforcing bars 81 should be tightened to the embedded reinforcing bars 41 through the screw hole at the cylindrical end of the reinforcing bar sleeve 42, and the other end should be lapped on the horizontal longitudinal reinforcing bars 82. The lap length should meet the requirements of the specification. The thickness of the concrete protective layer should not be less than 20mm, and the concrete strength grade is C40.

[0088] See Figure 5 and Figure 6For example, the high-pressure jet grouting pile 3 used has a double-layer cylindrical structure with a pile tip diameter larger than the pile top diameter, and the construction process adopts the double-pipe method. The pile tip diameter is 1.3m, the pile top diameter is 1.0m, the pile center distance is 1.6m, the average pile length is 18m, the pile tip enlargement structure has a pile length of 2m, and a first crushed stone cushion layer 6 is laid on the top of the pile tip with a thickness of about 1.3m, with an error of no more than ±20mm, and the mud content of the crushed stone is no more than 5%; the rigid pile composite foundation system used includes rigid piles 5 and pile caps 10. Rigid pile 5 can adopt PHC pile composite foundation, which consists of cylindrical pile body, end plate and steel sleeve, etc. The diameter of the pipe pile is 1.0m, the wall thickness is 0.125m, the pile length is 25.78m, and the concrete grade is C60 or above. The pile cap 10 is cast-in-place reinforced concrete, which is connected with the rigid pile 5 to form a complete system. Its outer thickness is 30mm, and its interior needs to penetrate into the steel pipe pile more than 70mm. The bottom end is sealed with a Q235 steel plate with a thickness of 8mm. The concrete grade is C40. The internal reinforcement of the pile cap 10 only needs to meet the structural requirements. The rigid pile 5 arranged under the load transfer structure 9 and the high-pressure jet grouting pile 3 under the driven pipe 4 are staggered in distribution.

[0089] See Figure 6 The high-pressure jet grouting piles 3 and rigid piles 5 are arranged in a group in a square distribution, with a pile spacing of 1.6m between piles of the same type and a pile spacing of 0.8m between high-pressure jet grouting piles 3 and rigid piles 5. The vertical ultimate bearing capacity of a single high-pressure jet grouting pile 3 is not less than 1000KN. The arrangement of rigid piles 5 can transfer part of the upper load from the side of the immersed tube 4 to the deep foundation, thereby reducing the load transferred to the bottom surface of the immersed tube 4 tunnel. The driving process of rigid piles 5 can put the foundation soil around the pile under lateral compression, which can play a role in compacting the foundation. At the same time, both rigid piles 5 and high-pressure jet grouting piles 3 have a replacement effect on the foundation soil. The pile foundation and the foundation soil share the load and cooperate in bearing the force. Furthermore, the enlarged pile end structure of the high-pressure jet grouting pile 3 proposed in this invention can suppress pile uplift and protect the structure from overturning damage. It has the advantages of low cost, convenient construction, high bearing capacity, good seismic performance, and good anti-buoyancy ability, and has broad prospects in the application of immersed tube tunnels.

[0090] See Figure 3 and Figure 4The load transfer structure 9 used, when the immersed tube 4 floats, not only needs to overcome the self-weight of the overlying soil on the load transfer structure 9, but also the self-weight stress of the soil on the wedge-shaped surface of the anti-buoyancy soil wedge 12 during upward pull-out, as well as the frictional force on the interface. It increases the overall strength of the immersed tube 4, which can better limit the settlement and deformation of the foundation soil, enhance the integrity of the system, reduce the internal stress of the structure, and improve the anti-buoyancy performance of the immersed tube 4. It can effectively solve the problem of uneven settlement of the immersed tube 4 tunnel, so that the upper load can be transferred downward to the foundation more evenly, thereby giving full play to the synergistic force-bearing effect of the composite foundation pile group; the enlarged structure at the pile end of the high-pressure jet grouting pile 3 also has the same effect.

[0091] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0092] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0093] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method of construction of a subsea immersed tube tunnel segment, characterised in that, It includes the following steps: The seabed (1) is excavated by slope to form a foundation trench (2); High-pressure jet grouting piles (3) are constructed at the bottom of the foundation trench (2); Enlarge the bottom end of the high-pressure jet grouting pile (3); A first crushed stone cushion layer (6) is laid at the bottom of the foundation trench (2), and the first crushed stone cushion layer (6) is compacted and leveled. The immersed tube (4) is suspended on the surface of the first crushed stone cushion layer (6); wherein at least a portion of the high-pressure jet grouting piles (3) are supported on the bottom of the immersed tube (4); A second crushed stone cushion layer (7) is laid at the bottom of the foundation trench (2) and compacted and leveled; wherein, the top surface height of the second crushed stone cushion layer (7) is lower than the top surface height of the submerged pipe (4); Rigid piles (5) are constructed on the top surface of the second crushed stone cushion layer (7); A pile cap (10) is constructed at the top of the rigid pile (5); wherein the cross-section of the pile cap (10) is larger than the bottom area of ​​the load transfer structure (9); Steel reinforcement assemblies (8) are built on the pre-embedded steel bars (41) on both sides of the immersed tube (4) so ​​that the pre-embedded steel bars (41) and the steel reinforcement assemblies (8) together form a steel cage; wherein the pre-embedded steel bars (41) are at least partially embedded in the immersed tube (4); Concrete is poured into the steel cage to form a load transfer structure (9) on the opposite side walls of the sinking tube (4); wherein the bottom of the load transfer structure (9) is connected to the top of the corresponding rigid pile (5). Backfill and compact the foundation trench (2) to complete the construction of the submerged pipe (4).

2. The construction method for the subsea immersed tunnel segment as described in claim 1, characterized in that: The pre-embedded steel bars (41) on the opposite side walls of the immersed tube (4) are each equipped with a steel reinforcement assembly (8), so that the pre-embedded steel bars (41) and the steel reinforcement assembly (8) together form a steel reinforcement cage, including: An extension bar (81) is screwed into the end of the embedded steel bar (41) to extend the length of the embedded steel bar (41); Longitudinal steel bars (82) are used to connect multiple extended steel bars (81) that are spaced apart along the length of the immersed tube (4) into a whole, thus completing the construction of the steel bar assembly (8).

3. The construction method for the subsea immersed tunnel segment as described in claim 1, characterized in that: Before the slope excavation of the seabed (1) to form the foundation trench (2), the following are included: Precast immersed tubes in the dry dock (4); Pre-embedded steel bars (41) are embedded in the opposite side walls of the immersed tube (4); wherein the pre-embedded steel bars (41) are at least partially located outside the immersed tube (4).

4. The construction method for the subsea immersed tunnel segment as described in claim 3, characterized in that: After embedding pre-embedded steel bars (41) in the opposite side walls of the immersed tube (4), the following is included: The embedded steel bars (41) are subjected to anti-corrosion treatment.

5. The construction method for the subsea immersed tunnel segment as described in claim 3, characterized in that: After embedding pre-embedded steel bars (41) in the opposite side walls of the immersed tube (4), the following is included: Weld a steel sleeve (42) to the end of the pre-embedded steel bar (41) and perform anti-corrosion treatment on the steel sleeve (42).

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