Temporary cofferdam structure construction method for accelerating butt joint of immersed tunnels in sea area and temporary cofferdam structure

Abstract

The invention discloses a temporary cofferdam structure construction method and temporary cofferdam structure for accelerating butt joint of immersed tunnels in a sea area, and the temporary cofferdam structure construction method for accelerating butt joint of the immersed tunnels in the sea area comprises the steps that after a dry construction environment is formed in an original cofferdam, a butt joint section foundation pit is excavated in the original cofferdam; after the tunnel structure is completed in the butt joint section foundation pit and backfill construction is carried out, construction is carried out above the tunnel structure, a temporary cofferdam structure connected with the two ends of the original cofferdam is formed, and the temporary cofferdam structure is used for isolating the butt joint section from the non-butt joint section; the original steel sheet pile cofferdam on the butt joint section, located on the outer side of the temporary cofferdam structure, of the original cofferdam is removed And the immersed tube joints immersed on the water are in butt joint with the tunnel structure, and internal structure construction of the area between the original cofferdam and the temporary cofferdam structure is conducted. Segmented isolation and advanced butt joint can be achieved, meanwhile, immersed tube butt joint and other areas of the cofferdam section are constructed in parallel, and therefore the construction period is shortened.

Description

Technical Field

[0001] The present application relates to the technical field of civil engineering, and particularly relates to a construction method for a temporary cofferdam structure for accelerating the docking of immersed tunnels in the sea area and a temporary cofferdam structure. Background Art

[0002] A sea area cofferdam is a temporary waterproof enclosure structure used for marine engineering construction; the forms of cofferdams generally include earth-rock cofferdams, steel sheet cofferdams, concrete cofferdams, etc. It is built in water to separate the construction area from the water area and create a relatively dry construction environment after draining the water. For the engineering situation where the cofferdam section needs to be docked with the immersed tube section, the cofferdam construction is carried out first, and after creating a dry construction environment, the internal structure construction is carried out. Only after all the internal structure construction is completed can the cofferdam be demolished and the cofferdam section and the immersed tube section be docked and connected. This construction process is a linear process. The order of first building the cofferdam and then the immersed tube lengthens the critical path of the project, resulting in an increase in the total construction period.

[0003] After the traditional cofferdam construction is completed, the internal structure is divided into several parts for construction to achieve the purpose of accelerating the construction. This method can accelerate the construction progress and save construction time to a certain extent. However, it is still necessary to wait until all the structure construction is completed before demolishing the cofferdam for immersed tube docking, so the entire construction period still requires a long time.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the Invention

[0005] The main purpose of the present application is to provide a construction method for a temporary cofferdam structure for accelerating the docking of immersed tunnels in the sea area and a temporary cofferdam structure, aiming to solve the problem in the prior art that after the cofferdam construction, the internal structure construction is carried out and then the cofferdam is demolished for immersed tube docking. The docking of the cofferdam section and the immersed tube section must wait for the completion of the internal structure construction. Therefore, the order of first building the cofferdam and then the immersed tube makes the critical path of the project longer, resulting in a longer total construction period of the project.

[0006] The first aspect of the embodiment of the present application provides a construction method for a temporary cofferdam structure for accelerating the docking of a submerged tube tunnel in the sea, which is applied to the temporary cofferdam structure. The temporary cofferdam structure is used to be installed in the original cofferdam in the sea area; the construction method for the temporary cofferdam structure for accelerating the docking of the submerged tube tunnel in the sea area includes: after forming a dry construction environment in the original cofferdam, excavating a docking section foundation pit in the original cofferdam; when the tunnel structure is completed and backfilled in the docking section foundation pit, constructing above the tunnel structure to form a temporary cofferdam structure connecting the two ends of the original cofferdam, wherein the temporary cofferdam structure is used to isolate the docking section from the non-docking section; demolishing the original steel sheet pile cofferdam of the docking section located outside the temporary cofferdam structure to enable seawater to flow back to the outside of the temporary cofferdam structure; docking the submerged tube segment placed on the water with the tunnel structure, and carrying out internal structure construction on the area between the original cofferdam and the temporary cofferdam structure.

[0007] Optionally, in an embodiment of the present application, the constructing above the tunnel structure to form a temporary cofferdam structure connecting the two ends of the original cofferdam specifically includes: constructing on both sides of the docking section to form two double-row steel pipe pile sub-cofferdams, and respectively fixedly connecting the two double-row steel pipe pile sub-cofferdams with the original cofferdam; constructing on the top of the tunnel structure to form a buttress retaining wall; connecting the two double-row steel pipe pile sub-cofferdams with the buttress retaining wall respectively to form a temporary cofferdam structure connecting the two ends of the original cofferdam.

[0008] Optionally, in an embodiment of the present application, the constructing on both sides of the docking section to form two double-row steel pipe pile sub-cofferdams specifically includes: driving the inner row of steel pipe piles and the outer row of steel pipe piles at the designed positions on one side of the docking section; installing locks between the inner row and the outer row of steel pipe piles respectively, and grouting the lock gap space to prevent water leakage, so as to form the inner row of steel pipe piles and the outer row of steel pipe piles connected by the concrete structure and the locks; installing H-shaped steel supports between the inner row of steel pipe piles and the outer row of steel pipe piles to form a double-row steel pipe pile sub-cofferdam on one side of the docking section.

[0009] Optionally, in an embodiment of the present application, the constructing on the top of the tunnel structure to form a buttress retaining wall specifically includes: pouring a wall at the set position on the top of the tunnel structure to form a retaining wall structure; arranging buttresses at a preset interval along the retaining wall structure, and arranging connecting beams between the buttresses to form a buttress retaining wall.

[0010] Optionally, in an embodiment of the present application, before demolishing the original steel sheet pile cofferdam of the docking section located outside the temporary cofferdam structure, it further includes: Backwater to the area between the temporary cofferdam structure and the original cofferdam, verify the tightness of the temporary cofferdam structure, and after ensuring no leakage, remove the original steel sheet pile cofferdam of the docking section of the original cofferdam.

[0011] In the second aspect of the embodiments of the present application, there is also provided a temporary cofferdam structure for implementing the construction method of the temporary cofferdam structure for accelerating the docking of the immersed tube tunnel in any one of the above solutions. Wherein, the temporary cofferdam structure includes a buttress retaining wall and two double-row steel pipe pile sub-cofferdams. One side of each of the two double-row steel pipe pile sub-cofferdams is respectively connected to both sides of the buttress retaining wall, and the other side of each of the two double-row steel pipe pile sub-cofferdams is used to be respectively connected to both ends of the original cofferdam. The buttress retaining wall is used to be installed on the top of the tunnel structure.

[0012] Optionally, in an embodiment of the present application, the double-row steel pipe pile sub-cofferdam includes an inner row of steel pipe piles and an outer row of steel pipe piles connected to each other. The inner row of steel pipe piles faces the inner side direction of the original cofferdam, and the outer row of steel pipe piles faces the sea area direction. Locking joints are respectively installed between the inner row of steel pipe piles and between the outer row of steel pipe piles.

[0013] Optionally, in an embodiment of the present application, the outer row of steel pipe piles is higher than the inner row of steel pipe piles, and H-shaped steel is used for support between the inner row of steel pipe piles and the outer row of steel pipe piles. A concrete structure is formed by grouting in the gap space of the locking joints.

[0014] Optionally, in an embodiment of the present application, each double-row steel pipe pile sub-cofferdam is fixedly connected to the original inner row of steel pipe piles of the original cofferdam through multiple rows of jet grouting piles.

[0015] Optionally, in an embodiment of the present application, the buttress retaining wall includes a buttress structure and a retaining wall structure. The retaining wall structure is located on the top of the tunnel structure. The height of the retaining wall on the water-facing side of the retaining wall structure is greater than the height of the retaining wall on the soil-facing side. The buttress structure abuts against the retaining wall structure, and a tie beam is arranged between the buttress structures. The buttress structure and the tie beam form a space frame for supporting the retaining wall structure.

[0016] Beneficial effects: The present application provides a construction method and a temporary cofferdam structure for accelerating the docking of an immersed tube tunnel in the sea area. The present application can achieve segmented isolation and early docking through the temporary cofferdam structure. By preferentially constructing the docking area for the docking of the immersed tube, a temporary cofferdam structure is formed on the original cofferdam to isolate seawater, the original steel sheet piles in the docking area are removed to release the working surface for the immersed tube operation, the underwater docking of the tunnel structures of the immersed tube section and the cofferdam section is carried out on the working surface, and at the same time, the construction of the internal structure in the non-docking area is carried out. After the construction in the docking area is completed, the local cofferdam can be removed, and the docking of the immersed tube and other areas of the cofferdam section are constructed in parallel, thereby reducing the construction period. Description of the Drawings

[0017] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is the plan layout diagram of the temporary cofferdam structure of the present application installed on the original cofferdam; Figure 2 It is the cross-sectional layout diagram in the preferred embodiment of the temporary cofferdam structure of the present application; Figure 3 It is the plan view of the intersection of the steel pipe piles of the sub-cofferdam and the steel sheet piles of the original cofferdam in the preferred embodiment of the temporary cofferdam structure of the present application; Figure 4 It is the sectional view of the counterfort retaining wall in the preferred embodiment of the temporary cofferdam structure of the present application Figure 5 It is the flow chart of the preferred embodiment of the construction method of the temporary cofferdam structure for accelerating the docking of the immersed tube tunnel in the sea area of the present application; Figure 6 It is the construction drawing of the counterfort retaining wall in the preferred embodiment of the construction method of the temporary cofferdam structure for accelerating the docking of the immersed tube tunnel in the sea area of the present application. Specific embodiments

[0019] To make the purpose, technical solutions and effects of the present application clearer and more definite, the following will clearly and completely describe the technical solutions in the embodiments of the present application in combination with the drawings in the embodiments of the present application. The described embodiments are only possible technical implementations of the present application, not all possible implementations. Based on the embodiments in the present application, those skilled in the art can fully combine the embodiments of the present application to obtain other embodiments without creative efforts, and these embodiments are also within the protection scope of the present application.

[0020] First, introduce the terms involved in the embodiments of the present application: Docking section: refers to the key area in the immersed tube tunnel that directly docks with the tunnel in the cofferdam section; the docking section is the core part of the construction and needs to be completed as early as possible to ensure the smooth progress of the immersed tube docking. Through the priority construction of the docking section in the present application, the conditions for the immersed tube docking can be formed as early as possible, creating conditions for the underwater engineering operations of the immersed tube segments; Non-docking section: It refers to other parts of the immersed tube tunnel that do not directly dock with the tunnel in the cofferdam section. The construction of the non-docking section can be carried out after the docking section is completed. The sub-cofferdam (temporary cofferdam structure) is used to cut off the sea water to ensure a dry construction environment, thus avoiding the drawback in traditional construction that the cofferdam must be removed for immersed tube docking only after the construction of the entire structure is completed.

[0021] The construction process of the related technology is "cofferdam first, then immersed tube", that is, cofferdam construction - internal structure construction - cofferdam removal - immersed tube docking. The cofferdam cannot be removed until all internal structures are completed, resulting in a long critical path and an uncompressible total construction period. Although in the optimization attempts of the related technology, in some projects, the internal structure is divided into multiple blocks for parallel construction (such as dividing into multiple construction sections), the sequence of "cofferdam first, then immersed tube" is still not changed, and the cofferdam cannot be removed until the entire section structure is completed, and segmented docking is not possible. Therefore, in the related technology, the cofferdam must be removed for immersed tube docking only after all internal structures of the cofferdam section are constructed, resulting in a long total construction period; construction equipment and personnel need to occupy the cofferdam for a long time, and resources cannot be released in stages; and if the construction of the cofferdam section is postponed (such as due to the deformation of the original cofferdam steel sheet due to typhoon weather), the subsequent immersed tube docking time will be directly compressed, resulting in an increase in the overall project risk.

[0022] In this application, by adding a sub-cofferdam (temporary cofferdam structure), the docking section and the non-docking section are divided, realizing parallel construction. The docking section is given priority in construction and the immersed tube docking is completed, and then the non-docking section is constructed, thus shortening the total construction period. That is, the foundation pit of the docking part is independently excavated first to form the conditions for immersed tube docking as early as possible. After the sub-cofferdam and the original steel sheet pile cofferdam form a whole and the water returns on the sub-cofferdam side, part of the original steel sheet pile cofferdam body is removed, and the related waterborne engineering operations of the immersed tube segment are started; after the construction of the docking section is completed, the sub-cofferdam is used to cut off the sea water to ensure a dry construction environment, and the construction of the non-docking section is continued. Therefore, in this application, through the division of the docking section and the non-docking section, construction resources (such as manpower and equipment) can be more reasonably allocated and utilized, and through parallel construction, the total construction period is significantly shortened, improving the construction efficiency. Therefore, this application can solve the problems of long construction period of the cofferdam section and delay in the docking of the cofferdam section and the immersed tube section.

[0023] The following describes a construction method for a temporary cofferdam structure and the temporary cofferdam structure for accelerating the docking of a submarine immersed tunnel in an embodiment of the present application with reference to the accompanying drawings. In view of the problem in the related technology that after the cofferdam construction, the internal structure is constructed and then the cofferdam is demolished for the immersed tube docking. The docking between the cofferdam section and the immersed tube section must wait for the completion of the internal structure construction. Therefore, the sequence of first constructing the cofferdam and then the immersed tube makes the critical path of the project longer, resulting in a longer total project duration. The present application provides a construction method for a temporary cofferdam structure for accelerating the docking of a submarine immersed tunnel. In this method, the present application can achieve segmented isolation and early docking through the temporary cofferdam structure. By preferentially constructing the docking area for the immersed tube docking, a temporary cofferdam structure is formed on the original cofferdam to isolate seawater. The original steel sheet piles in the docking area are demolished to release the working surface for the immersed tube operation. The underwater docking of the tunnel structures of the immersed tube section and the cofferdam section is carried out on the working surface, and at the same time, the construction of the internal structure in the non-docking area is carried out. After the construction in the docking area is completed, the local cofferdam can be demolished, and the immersed tube docking and the other areas of the cofferdam section are constructed in parallel, thereby reducing the construction duration, and the construction equipment exits in stages, reducing the risk of equipment congestion inside the cofferdam; in addition, even if the construction in the non-docking area is postponed and the immersed tube docking has been completed, the overall project risk is reduced. Thus, the technical problem in the related technology that after the cofferdam construction, the internal structure is constructed and then the cofferdam is demolished for the immersed tube docking. The docking between the cofferdam section and the immersed tube section must wait for the completion of the internal structure construction. Therefore, the sequence of first constructing the cofferdam and then the immersed tube makes the critical path of the project longer, resulting in a longer total project duration is solved.

[0024] The following specifically describes the technical solutions of the present application with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0025] As Figure 1 and Figure 2 shown, an embodiment of the present application provides a temporary cofferdam structure (i.e., a sub-cofferdam) for implementing a construction method for a temporary cofferdam structure for accelerating the docking of a submarine immersed tunnel. The temporary cofferdam structure includes a counterfort retaining wall and two double-row steel pipe pile sub-cofferdams. One side of each of the two double-row steel pipe pile sub-cofferdams is respectively connected to both sides of the counterfort retaining wall, and the other side of each of the two double-row steel pipe pile sub-cofferdams is used to be respectively connected to both ends of the original cofferdam (i.e., the original cofferdam). The counterfort retaining wall is used to be installed on the top of the tunnel structure.

[0026] It should be noted that referring to Figure 1 and Figure 3, the original cofferdam was a double-row steel sheet pile cofferdam, including the outer row of piles of the original double-row steel sheet pile cofferdam and the inner row of piles of the original double-row steel sheet pile cofferdam. The outer row of piles was close to the open sea side, and the construction environment inside the area enclosed by the inner row of piles was dry. A foundation pit was excavated in the butt joint section of the original cofferdam for the construction of the internal structure. After the tunnel structure was completed (the tunnel structure was sealed towards the open sea side), backfilling construction was carried out, and then a sub-cofferdam was formed corresponding to the top of the tunnel structure. Thus, after the original steel sheet pile cofferdam in the butt joint section of the original cofferdam was removed, the structural system formed by the original cofferdam and the sub-cofferdam blocked seawater from entering the internal area. Then, a ship was used to sink the immersed tunnel to the seabed and dock it with the tunnel structure of the butt joint section. At the same time, other internal structures could be constructed in parallel in the internal area of the structural system, thereby reducing the construction period and improving the construction efficiency.

[0027] It should be noted that the original cofferdam used steel sheet piles, and the sub-cofferdam used steel pipe piles.

[0028] Specifically, a temporary cofferdam structure was added on the basis of the original cofferdam to separate the butt joint part, so that after the butt joint part was constructed, part of the original cofferdam (i.e., Figure 1 the inner and outer rows of steel sheet piles at the left end of the original cofferdam in the figure) could be directly demolished. The temporary cofferdam structure was used to block seawater and ensure the docking of the butt joint part of the cofferdam and the immersed tube section.

[0029] Furthermore, in this embodiment, as shown in Figure 2 、 Figure 3 and Figure 4 , the sub-cofferdam mainly had two forms: double-row steel pipe piles and counterfort retaining walls. The inside and outside were backfilled with sandbags and geomembrane bags respectively. The double-row steel pipe pile sub-cofferdam type was adopted between both sides of the tunnel structure where the sub-cofferdam was located and the outer row of steel pipe piles of the original cofferdam; the counterfort retaining wall type was adopted at the top of the tunnel structure. The top of the outer row of steel pipe piles was slightly higher than that of the inner row of steel pipe piles. Locking joints were provided between the steel pipe piles, and grouting was used to stop water in the whole length range of the gap inside the locking joints. Steel supports were used between the inner and outer rows of steel pipe piles.

[0030] In this application, by adopting a structural system composed of the original cofferdam and the temporary cofferdam structure (i.e., the sub-cofferdam), sectional isolation and advance tunnel docking were realized, and the construction speed was accelerated and the construction period of the interval tunnel was shortened.

[0031] In an embodiment of this application, the double-row steel pipe pile sub-cofferdam includes connected inner row steel pipe piles and outer row steel pipe piles. The inner row steel pipe piles face the inner side direction of the original cofferdam, and the outer row steel pipe piles face the sea area direction. Locking joints are respectively installed between the inner row steel pipe piles and between the outer row steel pipe piles.

[0032] In an embodiment of this application, the outer row steel pipe piles are higher than the inner row steel pipe piles, and H-shaped steel supports are used between the inner row steel pipe piles and the outer row steel pipe piles. A concrete structure is formed by grouting in the gap space of the locking joints.

[0033] It is understandable that the H-shaped steel support is located between the inner and outer rows of steel pipe piles as an auxiliary structure and is fixed between the inner and outer rows of steel pipe piles by means of welding, bolts, etc. This connection method ensures that the H-shaped steel and the steel pipe piles form a stable framework to enhance the overall stability and load transfer capacity of the sub-coffer dam. When the inner and outer rows of steel pipe piles are subjected to lateral earth pressure or water pressure, they may deform or become unstable. The H-shaped steel support can improve the overall stability of the structure by providing lateral restraint; the H-shaped steel support can transfer part of the load from the outer row of steel pipe piles to the inner row of steel pipe piles, optimize the load distribution, and reduce the stress concentration on a single steel pipe pile.

[0034] Specifically, as Figure 2 and Figure 3 shown, on both sides of the sub-coffer dam to the outer row of steel pipe piles of the original coffer dam (the original coffer dam adopts a double-row steel pipe pile coffer dam structure), the sub-coffer dam adopts a double-row steel pipe pile type. The width of the double-row steel pipe pile coffer dam is 10.5 m, the elevation of the coffer dam top is +3.00 m, the elevation of the outer row of steel pipe pile tops is +6.00 m, the elevation of the inner row of steel pipe pile tops is +3.0 m, and the bottom elevations of the inner and outer rows of piles are -24 m. The steel pipe piles use an outer diameter of Φ820 and a wall thickness of 16 mm, and the material is Q355B (low-alloy high-strength structural steel). Locking connections are provided between the steel pipe piles, and grouting is used to stop water in the gap within the full length of the locking connection. H-shaped steel supports are used between the inner and outer rows of steel pipe piles, with a model of HW200×200×8×12 (the specification of the H-shaped steel, indicating a height of 200 mm, a width of 200 mm, a web thickness of 8 mm, and a flange thickness of 12 mm), a spacing of 2.0 m, and a center elevation of 2.5 m.

[0035] In an embodiment of the present application, each of the double-row steel pipe pile sub-coffer dams is fixedly connected to the original inner row of steel pipe piles of the original coffer dam through multiple rows of jet grouting piles.

[0036] Specifically, as Figure 2 and Figure 3 shown, in the layout of the connection nodes between the new and old coffer dam bodies, within the area enclosed by the double-row steel pipe pile sub-coffer dam and the original double-row steel sheet pile coffer dam, 3 rows of jet grouting piles are used for reinforcement in the handover area with the original inner and outer rows of steel pipe piles; at the handover position between the double-row steel pipe pile sub-coffer dam and the original inner row of steel pipe piles, 3 rows of jet grouting piles are provided for reinforcement near the side of the original steel sheet piles. The jet grouting piles use Φ700@500 (the diameter and spacing of the jet grouting piles, indicating a diameter of 700 mm and a spacing of 500 mm), the pile top elevation is +2.0 m, and the pile bottom elevation is -24 m.

[0037] In an embodiment of the present application, the buttress retaining wall includes a buttress structure and a retaining wall structure. The retaining wall structure is located on top of the tunnel structure. The height of the retaining wall on the water-facing side of the retaining wall structure is greater than the height of the retaining wall on the soil-facing side. The buttress structure abuts against the retaining wall structure, and a tie beam is arranged between the buttress structures. The buttress structure and the tie beam form a space frame for supporting the retaining wall structure.

[0038] Specifically, Figure 2 and Figure 4 As shown in the figure, the top of the tunnel adopts a buttress retaining wall. The top elevation of the buttress retaining wall facing the water is +6.0m, the retaining wall thickness is 600mm, 400mm thick buttresses are set at a horizontal interval of 4.7m to 5.6m along the tunnel, and two 400mm×600mm connecting beams are set between the buttresses; the top elevation of the retaining wall facing the soil on the north and south sides and the inner row of steel pipe piles is +3.0m, and the retaining wall thickness is 600mm.

[0039] In this application, the steel pipe piles of the sub-cofferdam are arranged in parallel with the steel sheet piles of the original cofferdam, and the connection nodes are reinforced by jet grouting piles. The sub-cofferdam is an extension of the original cofferdam, and together they form a waterproof barrier. In the longitudinal connection of the double-row steel pipe pile sub-cofferdam, the inner and outer rows of steel pipe piles are connected by steel supports to form a frame-type stable structure. In the transverse connection, the steel pipe piles are sealed by locks and grouting water stops, so that the inner and outer rows of steel pipe piles work together to resist soil pressure and water pressure. Locks and grouting water stops ensure waterproof performance. The buttress retaining wall is located at the top of the tunnel and is continuously arranged with the retaining wall of the connecting section of the inner row of steel pipe piles, forming a three-dimensional waterproof system with the steel pipe piles. The steel support is welded or bolted between the inner and outer rows of steel pipe piles to transfer the horizontal load to the inner row of piles, reduce the force on the outer row of piles, and improve the overall stability. The jet grouting piles penetrate into the junction area between the original steel sheet piles and the sub-cofferdam steel pipe piles to enhance the strength of the joint between the new and old weir bodies and prevent structural damage caused by settlement differences.

[0040] This application increases the construction efficiency by adding a sub-cofferdam structure, which is higher than the traditional cofferdam form, reduces the construction period, and saves investment. It can not only meet the requirements of speeding up construction, but also meet the remedial measures for the damage of the original cofferdam in extreme weather such as typhoons.

[0041] The temporary cofferdam structure construction method for accelerating the docking of immersed tube tunnels in sea areas described in the preferred embodiment of the present application is as follows: Figure 5 As shown, the temporary cofferdam structure construction method for accelerating the connection of immersed tube tunnels in the sea area is applied to a temporary cofferdam structure, and the temporary cofferdam structure is used to be installed on the original cofferdam in the sea area (i.e., the original cofferdam, the sea area cofferdam). The temporary cofferdam structure construction method for accelerating the connection of immersed tube tunnels in the sea area includes the following steps: In step S101, after a dry construction environment is formed in the original cofferdam, a foundation pit of a docking section is excavated in the original cofferdam.

[0042] Specifically, in the process of forming the construction environment, the water in the original cofferdam is drained through well point dewatering and other methods to form a dry construction environment, and the site is leveled to ensure the stability of the foundation for subsequent structural construction. Dewatering is a prerequisite for the construction of the cofferdam section, and site leveling provides a working surface for the construction of the retaining structure (original cofferdam + sub-cofferdam).

[0043] Specifically, the docking section foundation pit (i.e. the key area for docking with the immersed tube) is excavated first to create conditions for the docking of the immersed tube. The independent excavation of the docking section foundation pit in this application is the starting point for the key path optimization. By focusing resources to prioritize the completion of the docking area construction, space is provided for the subsequent sub-cofferdam implementation and cofferdam removal.

[0044] It is worth noting that during the construction of the docking section foundation pit first, after the water level in the cofferdam is reduced, the site is leveled, the enclosure structure is constructed, and the docking part of the foundation pit (i.e. the area to be docked with the immersed tube in the future) is excavated independently to form the conditions for the immersed tube docking as soon as possible. The purpose is to buy time for the immersed tube docking and avoid the disadvantage of waiting for the completion of all structural construction in the traditional process.

[0045] In step S102, after the tunnel structure is completed and backfilled in the docking section foundation pit, construction is carried out above the tunnel structure to form a temporary cofferdam structure connecting the two ends of the original cofferdam, wherein the temporary cofferdam structure is used to isolate the docking section from the non-docking section.

[0046] In a possible implementation, construction is carried out on both sides of the docking section to form two double-row steel pipe pile cofferdams, and the two double-row steel pipe pile cofferdams are fixedly connected to the original cofferdam respectively; construction is carried out on the top of the tunnel structure to form a buttress retaining wall; the two double-row steel pipe pile cofferdams are connected to the buttress retaining wall respectively to form a temporary cofferdam structure connecting the two ends of the original cofferdam.

[0047] In a possible implementation, on one side of the docking section, an inner row of steel pipe piles and an outer row of steel pipe piles are driven into the designed position; lock buckles are installed between the inner and outer rows of the steel pipe piles, respectively, and grouting is performed in the gaps between the lock buckles to prevent water leakage, thereby forming an inner row of steel pipe piles and an outer row of steel pipe piles connected to the steel pipe piles through the concrete structure and the lock buckles; H-shaped steel supports are installed between the inner row of steel pipe piles and the outer row of steel pipe piles to form a double-row steel pipe pile cofferdam on one side of the docking section.

[0048] Specifically, the double-row steel pipe pile cofferdam serves as the main supporting structure of the sub-cofferdam, isolating the docking section from the non-docking section water area, and providing a dry construction environment for the immersed pipe docking. During the construction process, the steel pipe piles are first sunk, and the outer and inner rows of steel pipe piles are sunk according to the designed position to ensure the verticality and pile bottom elevation are accurate; then the lock connection and grouting water stop are carried out, and the lock is installed between the steel pipe piles to form a tight connection, and the gap inside the lock is grouted throughout the length to ensure the water stop effect. Finally, the H-shaped steel support is installed between the inner and outer rows of steel pipe piles at a spacing of 2.0m, with a center elevation of 2.5m to enhance the structural stability.

[0049] In a possible implementation, a wall is cast at a set position on the top of the tunnel structure to form a retaining wall structure; buttresses are arranged at a preset spacing along the retaining wall structure, and tie beams are arranged between the buttresses to form a buttressed retaining wall.

[0050] Specifically, the buttressed retaining wall serves as a lateral support structure at the top of the tunnel, enhancing the stability of the sub-cofferdam under the action of horizontal loads (such as earth pressure and wave force). The retaining wall and the buttresses are integrated. During the construction process, the buttressed retaining wall is constructed by longitudinal integral horizontal layering. The bottom slab is constructed simultaneously with the top slab of the tunnel structure, and the remaining part is constructed in three layers according to the tie beams, as Figure 6 shown. The steel bars of the buttressed retaining wall are cut and fabricated at the steel bar distribution center and then transported to the site for installation; the formwork is fixed with tie rods using wooden formwork; the concrete is centrally mixed at the concrete mixing center, pumped into the formwork in layers, and vibrated with internal vibrators.

[0051] It should be noted that the construction of the double-row steel pipe pile sub-cofferdam and the buttressed retaining wall needs to be carried out synchronously to ensure mutual support during the formation of the two structures. After the steel pipe piles are sunk, the lock connection, grouting for water stop, and installation of H-shaped steel supports are carried out immediately; at the same time, the construction of the main body of the retaining wall and the installation of the buttresses and tie beams need to be closely connected. The double-row steel pipe pile sub-cofferdam provides underwater support and isolation functions, and the buttressed retaining wall provides lateral support at the top, enhancing the overall stability. The water pressure and earth pressure borne by the sub-cofferdam are transmitted to the inner row of steel pipe piles through the H-shaped steel supports, and the lateral loads borne by the retaining wall are transmitted to the foundation through the buttresses and tie beams.

[0052] It is worth noting that during the construction of the isolation docking section of the sub-cofferdam, after the foundation pit of the docking section is completed, the sub-cofferdam (the temporary cofferdam structure of double-row steel pipe piles + buttressed retaining wall) is constructed. The sub-cofferdam and the original steel sheet pile cofferdam form an integral structural system, and the water returns on the side of the sub-cofferdam to create a dry construction environment for the docking section. Then, part of the original steel sheet pile cofferdam body (only the original cofferdam part corresponding to the docking section) is demolished, and then the related waterborne engineering operations of the immersed tube segment are started. The sub-cofferdam of the present application replaces the function of the original cofferdam in the docking section, enabling partial demolition of the original cofferdam and providing space for the immersed tube docking.

[0053] In step S103, the original steel sheet pile cofferdam of the docking section of the original cofferdam located outside the temporary cofferdam structure is demolished so that the seawater flows back to the outside of the temporary cofferdam structure.

[0054] In a possible implementation, water is returned to the area between the temporary cofferdam structure and the original cofferdam to verify the sealing performance of the temporary cofferdam structure. After ensuring no leakage, the original steel sheet pile cofferdam of the docking section of the original cofferdam is demolished.

[0055] Specifically, water is returned to the area between the sub-cofferdam and the original cofferdam to verify the sealing of the sub-cofferdam; after confirming that there is no leakage, the original steel sheet pile cofferdam of the docking section is removed to release the immersed tube docking operation surface. The original cofferdam can be safely removed only after the sub-cofferdam is ensured to be reliable through the backwater test in this application. Therefore, the removal of the original cofferdam in this application advances the starting point of the immersed tube docking, breaking the dependency relationship in the relevant process that all internal structures need to be completed before the cofferdam is removed for immersed tube docking, and thus this application can reduce the construction period and improve construction efficiency.

[0056] After the sub-cofferdam in this application forms a whole with the original steel sheet pile cofferdam and the water returns on the side of the sub-cofferdam, part of the original steel sheet pile weir body is dismantled and the related water engineering operations of the submerged pipe segments are started to create conditions for the sinking of the pipe segments.

[0057] In step S104, the immersed tube segment placed above water is docked with the tunnel structure, and the internal structure of the area between the original cofferdam and the temporary cofferdam structure is constructed.

[0058] Specifically, in the docking section where the original cofferdam has been removed, the immersed tube sections are placed and docked in water, while the internal structure of other areas of the cofferdam section is continued under the protection of the sub-cofferdam. The isolation effect of the sub-cofferdam allows the construction of immersed tube docking and other areas of the cofferdam section to be carried out in parallel, thus shortening the construction period.

[0059] It is worth noting that after the construction of the docking section is completed, the present application will carry out the parallel construction of the docking and other cofferdam sections, use the sub-cofferdam (temporary cofferdam structure) to isolate the seawater, ensure the dryness of the construction environment, and continue the construction of the non-docking section, including the construction of other foundation pits in the cofferdam section and the docking work between the immersed tube section and the cofferdam section. After the construction of the docking section is completed, the partition function of the sub-cofferdam will be used to ensure the smooth progress of the construction of the non-docking section.

[0060] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0061] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of this application, the meaning of "N" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0062] Any process or method description represented in a flowchart or otherwise described herein may be understood to represent a module, segment, or portion of code including one or N executable instructions for implementing a customized logical function or process, and the scope of the preferred embodiments of this application includes additional implementations, where the functions may be executed in a substantially simultaneous manner or in a reverse order according to the functions involved, rather than in the order shown or discussed, which should be understood by those skilled in the technical field to which the embodiments of this application belong.

[0063] The logic and / or steps represented in a flowchart or otherwise described herein, for example, may be considered as an ordered list of executable instructions for implementing a logical function, and may be specifically implemented in any computer-readable storage medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or in conjunction with such instruction execution systems, apparatuses, or devices. For the purposes of this specification, a "computer-readable storage medium" may be any device that can contain, store, communicate, propagate, or transport a program for use by or in conjunction with an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable storage media include the following: an electrical connection portion with one or N wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable storage medium may even be paper or other suitable media on which the program can be printed, as the program can be obtained electronically by optically scanning the paper or other media, followed by editing, interpretation, or otherwise processing as appropriate, and then stored in a computer memory.

[0064] It should be understood that each part of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0065] Those of ordinary skill in the art can understand that all or part of the steps carried by the methods of the above embodiments can be completed by instructing relevant hardware through a program. The said program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0066] In addition, in each embodiment of the present application, the functional units can be integrated in a processing module, or each unit can exist physically alone, or two or more units can be integrated in a module. The above integrated module can be implemented in the form of hardware or in the form of a software functional module. When the above integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0067] The above-mentioned storage medium can be a read-only memory, a magnetic disk, an optical disc, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

[0068] It should be understood that the application of the present application is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description. All such improvements and transformations should fall within the protection scope of the appended claims of the present application.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for constructing a temporary cofferdam structure to accelerate the docking of immersed tube tunnels in sea areas, characterized in that: Applicable to temporary cofferdam structures, which are used to be installed in the original cofferdam in the sea area; The temporary cofferdam structure construction method for accelerating the connection of immersed tube tunnels in the sea area includes: After a dry construction environment is formed in the original cofferdam, a foundation pit for a docking section is excavated in the original cofferdam; After the tunnel structure is completed and backfilled in the foundation pit of the docking section, construction is carried out above the tunnel structure to form a temporary cofferdam structure connecting the two ends of the original cofferdam, wherein the temporary cofferdam structure is used to isolate the docking section from the non-docked section; The original steel sheet pile cofferdam of the docking section of the original cofferdam located outside the temporary cofferdam structure is dismantled to allow the seawater to flow back to the outside of the temporary cofferdam structure; The immersed tube segment sunk above water is connected to the tunnel structure, and the internal structure of the area between the original cofferdam and the temporary cofferdam structure is constructed.

2. The temporary cofferdam structure construction method for accelerating the docking of immersed tube tunnels in sea areas according to claim 1 is characterized in that: The construction is performed above the tunnel structure to form a temporary cofferdam structure connecting the two ends of the original cofferdam, specifically including: Construction is performed on both sides of the butt joint section to form two double-row steel pipe pile cofferdams, and the two double-row steel pipe pile cofferdams are fixedly connected to the original cofferdam respectively; constructing a buttress retaining wall on top of the tunnel structure; The two double-row steel pipe pile cofferdams are respectively connected to the buttress retaining wall to form a temporary cofferdam structure connecting the two ends of the original cofferdam.

3. The method for constructing a temporary cofferdam structure for accelerating the docking of immersed tube tunnels in sea areas according to claim 2 is characterized in that: The construction is carried out on both sides of the docking section to form two double-row steel pipe pile cofferdams, specifically including: On one side of the butt joint section, driving the inner row of steel pipe piles and the outer row of steel pipe piles according to the designed positions; Install lock buckles between the inner and outer rows of steel pipe piles respectively, and inject grout into the gaps between the lock buckles to prevent water leakage, so as to form inner and outer rows of steel pipe piles connected by concrete structure and the lock buckles; H-shaped steel supports are installed between the inner row of steel pipe piles and the outer row of steel pipe piles to form a double-row steel pipe pile cofferdam on one side of the docking section.

4. The method for constructing a temporary cofferdam structure for accelerating the docking of immersed tube tunnels in sea areas according to claim 2 is characterized in that: The construction on the top of the tunnel structure to form a buttress retaining wall specifically includes: Casting a wall at a set position on the top of the tunnel structure to form a retaining wall structure; Buttresses are arranged along the retaining wall structure at preset intervals, and connecting beams are arranged between the buttresses to form a buttress retaining wall.

5. The method for constructing a temporary cofferdam structure for accelerating the docking of immersed tube tunnels in sea areas according to any one of claims 1 to 4, characterized in that: The dismantling of the original steel sheet pile cofferdam at the docking section of the original cofferdam outside the temporary cofferdam structure also includes: Water is returned to the area between the temporary cofferdam structure and the original cofferdam to verify the sealing of the temporary cofferdam structure to ensure that there is no leakage before dismantling the original steel sheet pile cofferdam at the docking section of the original cofferdam.

6. A temporary cofferdam structure for realizing the temporary cofferdam structure construction method for accelerating the docking of immersed tube tunnels in sea areas as described in any one of claims 1 to 5, characterized in that: The temporary cofferdam structure includes a buttress retaining wall and two double-row steel pipe pile cofferdams, one side of the two double-row steel pipe pile cofferdams is respectively connected to the two sides of the buttress retaining wall, and the other side of the two double-row steel pipe pile cofferdams is used to respectively connect the two ends of the original cofferdam, and the buttress retaining wall is used to be installed on the top of the tunnel structure.

7. The temporary cofferdam structure according to claim 6, characterized in that: The double-row steel pipe pile cofferdam includes an inner row of steel pipe piles and an outer row of steel pipe piles that are connected. The inner row of steel pipe piles faces the inner side of the original cofferdam, and the outer row of steel pipe piles faces the sea. Locking buckles are installed between the inner row of steel pipe piles and the outer row of steel pipe piles respectively.

8. The temporary cofferdam structure according to claim 7, characterized in that: The outer row of steel pipe piles is higher than the inner row of steel pipe piles, and H-shaped steel is used to support the inner row of steel pipe piles and the outer row of steel pipe piles. The gap space of the lock buckle is formed with a concrete structure by grouting.

9. The temporary cofferdam structure according to claim 6, characterized in that: Each of the double-row steel pipe pile cofferdams is fixedly connected to the original inner row of steel pipe piles of the original cofferdam through multiple rows of jet grouting piles.

10. The temporary cofferdam structure according to claim 6, characterized in that: The buttress retaining wall includes a buttress structure and a retaining wall structure. The retaining wall structure is located at the top of the tunnel structure. The height of the retaining wall on the water-facing side of the retaining wall structure is greater than the height of the retaining wall on the soil-facing side. The buttress structure is abutted against the retaining wall structure. Connecting beams are arranged between the buttress structures. The buttress structure and the connecting beams form a space frame for supporting the retaining wall structure.

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