Method for advance construction of underground structures for reclamation projects

Abstract

This invention discloses a method for pre-construction of underground structures in land reclamation projects, comprising the following steps: Prefabrication of underground engineering unit structures: Based on the purpose, load, and functional requirements of the underground project, a main structure is designed and divided into multiple unit structures. Each unit structure is prefabricated according to design conditions, with pre-reserved interfaces for assembly; underwater soft soil reinforcement is carried out on the predetermined area where the underground project will be constructed; the unit structures from step one are floated to the predetermined area and sunk to the predetermined position for assembly to form the main structure; land is formed by filling material outside the assembled unit structures; the fill material inside the unit structures is cleaned and transported out; the walls at the interfaces are removed, allowing the internal spaces of adjacent unit structures to be interconnected; and the upper area of ​​the underground structure is constructed. This method solves the problems of long construction periods, high costs, and high risks associated with traditional underground engineering structures in land reclamation projects.

Description

Technical Field

[0001] This invention relates to the field of land reclamation engineering technology, and in particular to a method for the preliminary construction of underground structures in land reclamation projects. Background Technology

[0002] With the development of coastal cities, land resources are becoming increasingly scarce, leading to numerous land reclamation projects in major cities worldwide. Typically, this involves filling large quantities of silt, sand, and gravel to form land, followed by extensive preliminary ground treatment to ensure the site is suitable for engineering equipment access. Then, the site is supported, excavated, and finally, underground structures are constructed. This process involves three key stages: land reclamation, preliminary treatment, and excavation. Each stage involves substantial earthwork, ground treatment, and excavation, resulting in significant waste of resources and time. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for the preliminary construction of underground structures in land reclamation projects, thereby solving the problems of long construction periods, high costs, and high risks associated with traditional land reclamation underground engineering.

[0004] This invention is achieved using the following technical solution: A method for pre-construction of underground structures in a land reclamation project includes the following steps: Step 1: Prefabrication of underground engineering unit structures: Based on the purpose, load and functional requirements of the underground engineering, the main structure is designed and divided into multiple unit structures. Each unit structure is prefabricated according to the design conditions and interfaces are reserved for docking and assembly. Step 2: Reinforce the underwater soft soil foundation of the designated area where underground engineering is to be constructed; Step 3: Float the unit structure from Step 1 to the designated area and sink it in the designated position for docking to form the main structure; Step 4: Fill the outside of the docked unit structure with boulders to form land. Step 5: Clean out and remove the packing material inside the unit structure; Step 6: Remove the wall at the interface to make the internal space of the two adjacent unit structures interconnected; Step 7: Construct the upper part of the underground structure.

[0005] Furthermore, in step one, the division method is determined according to the project type: for linear projects, the main structure is divided into multiple unit structures along its length, and interfaces are set between each unit structure through the connection between the beginning and end; for planar projects, the main structure is divided into multiple unit structures according to the spatial position of the unit structures in the main structure, and interfaces are set between each unit structure on at least one of the front, back, left, and right faces.

[0006] Furthermore, in step one, the unit structure is a hollow frame structure made of concrete, and the hollow frame structure includes various components such as columns, beams, slabs, and walls.

[0007] Furthermore, the interface is located at the boundary of the unit structure and at the intersection of at least two types of components among the columns, beams, and walls.

[0008] Furthermore, the interface is a concrete protrusion that protrudes inward from the surface of the unit structure body. In step three, when the unit structures are docked, the end faces of the interface abut against each other to provide initial positioning and support.

[0009] Furthermore, in step six, after removing the wall at the interface, if there is misalignment at the interface of two adjacent unit structures, the unit structure with the lower position is lifted to correct the misalignment.

[0010] Furthermore, after the lifting and correction, a reinforcing structure is installed at the interface between two adjacent unit structures.

[0011] Furthermore, the reinforcing structure is a ring-shaped steel structure surrounding the interface. When uneven settlement occurs between two adjacent unit structures, the overall stiffness of the ring-shaped steel structure resists the slippage and opening at the interface, thereby limiting the relative displacement of the two adjacent unit structures.

[0012] Furthermore, the annular steel structure is fixedly connected to the interface by multiple anchors, which are evenly distributed along the inner and outer edges of the annular steel structure.

[0013] Furthermore, the unit structure at a relatively lower position is lifted and corrected, specifically by: drilling grouting holes on the unit structure at a position adjacent to the interface; and injecting pressure grout into the bottom of the unit structure through the grouting holes, using the lifting force of the grout to lift the unit structure to be flush with the adjacent unit structure.

[0014] Compared with the prior art, the beneficial effects of the present invention include at least the following: This invention divides the main structure of underground engineering into multiple prefabricated unit components, with interfaces pre-reserved for subsequent assembly. By prioritizing the construction of the underground structure before the land is formed, repeated backfilling, treatment, and excavation can be avoided, significantly improving work efficiency and reducing construction costs. Simultaneously, it mitigates safety and quality risks during underground structure construction, and the sand and gravel filling the unit structures can be used for other engineering projects, reducing transportation costs. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the unit structure according to an embodiment of the present invention; Figure 2 This is a cross-sectional view of the unit structure according to an embodiment of the present invention; Figure 3 This is a linear engineering schematic diagram of multiple unit structures spliced ​​together according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a planar engineering structure formed by splicing multiple unit structures according to an embodiment of the present invention; Figure 5 This is a schematic diagram of an underwater soft soil reinforcement structure according to an embodiment of the present invention; Figure 6 This is a schematic diagram of a linear engineering structure being submerged on an underwater soft foundation processing structure according to an embodiment of the present invention; Figure 7 This is a schematic diagram of a reinforcing structure provided at the interface between two adjacent unit structures in an embodiment of the present invention; Figure 8 This is a structural diagram of the reinforced structure according to an embodiment of the present invention; In the diagram: 1. Unit structure; 11. Column; 12. Beam; 13. Slab; 14. Wall; 15. Interface; 2. Reinforcing structure; 21. Hole; 3. Anchor; 4. Grouting hole; 5. Linear engineering; 6. Surface engineering; 7. Underwater soft soil foundation reinforcement structure; 71. Pile; 72. Cushion layer. Detailed Implementation

[0016] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted.

[0017] The terms used to express position and direction in this invention are illustrated with reference to the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this invention.

[0018] like Figures 1 to 8 As shown, the present invention provides a method for the preliminary construction of underground structures in land reclamation projects, comprising the following steps: Step 1: Prefabrication of underground engineering unit structure 1: Based on the purpose, load and functional requirements of the underground engineering, the main structure is designed and divided into multiple unit structures 1. Each unit structure 1 is prefabricated according to the design conditions and an interface 15 is reserved for docking and assembly. Step 2: Reinforce the underwater soft soil foundation of the designated area where underground engineering is to be constructed; Step 3: Float the unit structure 1 from Step 1 to the designated area and sink it in the designated position for docking to form the main structure; Step 4: Fill the outside of the docked unit structure 1 with boulders to form land; Step 5: Clean out and remove the packing material inside unit structure 1; Step 6: Remove the wall 14 at interface 15 to make the internal spaces of the two adjacent unit structures 1 interconnected; Step 7: Construct the upper part of the underground structure.

[0019] In this embodiment, the prefabrication of the underground engineering unit structure 1 and the underwater soft soil foundation treatment can be carried out simultaneously to save construction time. In step one, the underground unit structure 1 is constructed first, avoiding the need for backfilling, foundation treatment, excavation, and structural construction, which significantly reduces construction costs and time. The backfill material (such as sand and gravel) used in unit structure 1 can be used for other engineering construction, reducing the transportation costs of engineering materials. Unit structure 1 can be prefabricated in a factory or on-site, making it easier to ensure its quality. It avoids safety and quality risks during the construction of underground structures (especially foundation pit excavation). In step two, according to the planning situation, the predetermined area where the underground engineering needs to be constructed is reinforced with underwater soft soil. The underwater soft soil foundation reinforcement structure 7 includes underwater piles 71 and a cushion layer 72 set on the piles 71. The piles 71 can be underwater DCM piles, underwater crushed stone piles, or underwater compacted sand piles. After the underwater soft soil foundation is reinforced, after excavation, laying of the crushed stone cushion layer 72, and underwater vibration leveling, it is ready for the sinking of unit structure 1. Next, unit structure 1 is floated sequentially to the designated area. After precise positioning, it is filled with sand, stones, and water to sink it to the designated position. After all the underground engineering structures in a certain area are sunk, if the underground structure has formed a enclosure, land can be directly filled with materials to form land. If the underground engineering structure in that area is not completely enclosed, an enclosure structure is added at the unenclosed area before filling with materials to form land. After the land is formed and preliminary foundation treatment is completed, and conditions are met for the entry of large engineering equipment, the filler in unit structure 1 is removed and transported out. Then, the wall 14 in interface 15 is demolished. If there is a significant misalignment at interface 15 between two unit structures 1, a hole can be drilled and grout injected at the interface 15 of the unit with the lower relative position to raise its structure until there is no significant misalignment between the two relative structures. Then, the structure at interface 15 is reinforced to reduce the impact of uneven settlement on the structure in the later stage, reduce operating costs, and improve structural stability. In step seven, according to the regional plan, subsequent construction is carried out on the upper part of the underground structure, such as road paving, greening construction, and plaza construction.

[0020] This invention prioritizes the construction of underground engineering structures before the land is formed in land reclamation projects, avoiding repeated backfilling, treatment, and excavation, significantly improving work efficiency and reducing construction costs. Simultaneously, it mitigates safety and quality risks during underground structure construction, and the sand and gravel filling unit 1 can be used for other engineering projects, reducing transportation costs.

[0021] As a preferred embodiment, in step one, the division method is determined according to the project type: for linear project 5, the main structure is divided into multiple unit structures 1 along its length direction, and each unit structure 1 is connected by an interface 15 at the beginning and end; for planar project 6, the main structure is divided into multiple unit structures 1 according to the spatial position of the unit structure 1 in the main structure, and each unit structure 1 is connected by an interface 15 on at least one of the front, back, left and right faces.

[0022] In this embodiment, linear engineering 5 includes structures such as underground utility tunnels, subways, and underpasses, while planar engineering 6 includes underground parking lots, underground shopping malls, and underground civil defense facilities. The method of differentiated unit division of the main structure based on engineering type (linear engineering 5 and planar engineering 6) differs from traditional, singular division methods. This invention successfully extends the advantages of prefabrication and assembly technology to similar underground engineering fields by defining two core division logics. Whether it's linear engineering 5 extending in the direction of extension (such as utility tunnels and tunnels) or planar engineering 6 unfolding in the plane (such as underground plazas and parking lots), an optimal unit division strategy can be found. This allows the modern construction model of "design-factory prefabrication-on-site assembly" to be widely applied to various underground space developments, greatly improving the versatility and market adaptability of the method. Furthermore, the division method is not mechanical cutting but rather a deep optimization based on engineering mechanics characteristics and functional requirements. For linear engineering 5, division along the length direction makes each unit a "segment" primarily bearing axial loads, which best conforms to the force transmission path of the structure, ensuring the continuity of the tunnel or utility tunnel in the length direction. For planar project 6, the planar division (with interfaces 15 at the front, back, left, and right) decomposes the large flat structure into several standardized panels supported by a column grid, perfectly matching the force-bearing principle of a plate-shell structure. This structural behavior-based division ensures from the outset that the prefabricated units can work collaboratively as a whole after assembly, with structural performance superior to or equivalent to cast-in-place structures. Furthermore, targeted division facilitates the formation of standardized unit modules. Linear project 5 can generate a series of longitudinal units with similar dimensions and reinforcement; planar project 6 can form standard "grid units" in space. This standardization greatly simplifies mold design and production processes in the factory, enabling batch, assembly-line prefabrication production, thereby significantly improving prefabrication efficiency and reducing the production cost of individual components. Moreover, the division method makes the interface 15 arrangement regular and clear. In linear project 5, all interfaces 15 are located at the beginning and end, making the construction process like "assembling a chain," simple and efficient. In planar project 6, interfaces 15 are located around the unit, similar to "puzzle pieces," facilitating simultaneous assembly operations from multiple directions. This regularity simplifies construction organization, reduces the complexity of on-site decision-making, and improves the speed and accuracy of hoisting, docking, and connection operations, fundamentally shortening the construction period. The partitioning method also fully considers the rationality of component dimensions. By partitioning the massive underground structure into unit components whose size and weight are within the capabilities of conventional transport vehicles and lifting equipment, the transportation and hoisting challenges of oversized and overweight components are effectively solved, reducing reliance on special equipment and making construction organization more flexible and economical.

[0023] Therefore, the differentiated unit division method proposed in this invention is a key bridge connecting "prefabricated design" and "efficient assembly." While ensuring structural safety and reliability, it achieves comprehensive optimization of production efficiency, construction speed, and construction costs, providing core technological support for promoting the modernization of underground engineering construction methods.

[0024] In a preferred embodiment, in step one, the unit structure 1 is a hollow frame structure made of concrete, and the hollow frame structure includes various components such as columns 11, beams 12, slabs 13, and walls 14.

[0025] Specifically, the interface 15 is set at the boundary of the unit structure 1 and is located at the intersection of at least two types of components among the column 11, beam 12 and wall 14.

[0026] In this embodiment, after the top plate 13 of unit structure 1 is lowered to the predetermined position, the capping construction or temporary capping is carried out according to the actual application. The shape of the interface 15 can be circular or square. By setting the interface 15 at the nodes of the main load-bearing components such as wall 14, column 11, and beam 12, it is ensured that when two unit structures 1 are connected, the interface 15 can effectively transfer the huge load (such as bending moment and shear force) to the "skeleton" (column 11, beam 12, plate 13, and wall 14) of the entire unit structure 1, realizing the smooth transmission of force and ensuring the stability of the overall structure.

[0027] In a preferred embodiment, the interface 15 is a concrete protrusion that protrudes inward from the surface of the unit structure 1. In step three, when the unit structures 1 are docked, the end faces of the interface 15 abut against each other to provide initial positioning and support.

[0028] In this embodiment, the interface 15 is housed within the contour of the unit body, rather than being an additional appendage on the outside of the unit structure 1. This ensures that the outer contour of the unit structure 1 is regular during placement, relying primarily on the structure itself for positioning and alignment. This avoids collisions and jamming of the protruding interface 15 during placement, thus guaranteeing the accuracy of the initial positioning. Subsequent precise positioning and rigid connection are then achieved through the interface 15 reinforcement mechanism to complete the fixed connection.

[0029] In a preferred embodiment, after lifting and correction, a reinforcing structure 2 is provided at the interface 15 between two adjacent unit structures 1. This is for the prefabricated unit structure 1. In this embodiment, the reinforcing structure 2 provides a strong circumferential constraint force for the interface 15. When uneven settlement occurs in the foundation, the reinforcing structure 2 can effectively disperse and transfer the local concentrated stress to the entire unit structure 1, thereby greatly suppressing the relative vertical displacement, horizontal slippage and opening deformation at the interface 15, ensuring the continuity, stability and safety of the overall structure of the underground project.

[0030] Specifically, the reinforcing structure 2 is a ring-shaped steel structure surrounding the interface 15. When two adjacent unit structures 1 experience uneven settlement, the overall stiffness of the ring-shaped steel structure resists the slippage and opening at the interface 15, thereby limiting the relative displacement of the two adjacent unit structures 1.

[0031] Specifically, the annular steel structure is fixedly connected to the interface 15 by a plurality of anchors 3, and the anchors 3 are evenly distributed along the inner and outer edges of the annular steel structure.

[0032] refer to Figure 7-8 The core function of the reinforcing structure 2 is to provide circumferential constraint to the interface 15 after two adjacent unit structures 1 are joined at the interface 15, thereby effectively resisting harmful relative displacements such as vertical misalignment, horizontal slippage, or opening of the interface 15 caused by uneven foundation settlement between the two units. The main body of the reinforcing structure 2 is a ring-shaped steel strip with a specific width. Preferably, it can be formed by rolling and welding high-strength steel plates (e.g., Q345B steel) to form a rigid closed ring. In another embodiment, it can also be formed by bending and welding shaped steel sections (such as channel steel or angle steel). The ring-shaped steel structure is fixed to the interface 15 by multiple anchors 3. Preferably, the anchors 3 can be anchor bolts, preferably high-strength chemical anchors or anchoring steel bars. The anchors 3 are evenly distributed along the inner and outer edges of the ring-shaped steel structure to ensure that the constraint force is evenly transmitted to the unit structure 1. Based on the dimensions of interface 15 of unit structure 1, the annular steel structure is precisely cut and fabricated in the factory. Holes 21 for installing anchor bolts are drilled at predetermined positions (inner and outer rings) of the annular steel structure. After the wall 14 at the interface 15 of the two unit structures 1 is removed, the concrete at the interface 15 is cleaned to ensure it is flat and clean. Then, the annular steel structure is fitted onto or tightly against the interface 15 for initial positioning. Through the holes 21 on the annular steel structure, holes are pre-drilled on the lower interface 15. Anchor bolts are inserted into the holes, or other reliable anchoring techniques are used to ensure a tight fit between the annular steel structure and the interface 15, achieving the designed preload. Ensure that all anchors 3 are installed according to design requirements.

[0033] The annular steel structure of this invention forms a high-rigidity "hoop" that tightly "hugs" the interface 15 of the two unit structures 1 together. When uneven settlement occurs, this structure, through its circumferential stiffness, disperses localized concentrated stress across the entire annular component, effectively suppressing deformation of the interface 15. For example, when the left unit structure 1 shows a tendency to sink, the annular steel structure, through the synergistic effect of its lower edge and anchorage 3, transforms the downward shear force into a constraint force on the structure, greatly improving the shear resistance of the interface 15 and preventing significant "step-like" misalignment. Simultaneously, the annular structure effectively prevents the interface 15 from opening due to deformation. Furthermore, the evenly distributed anchorage groups on both the inner and outer rings provide strong anchoring force, avoiding stress concentration and ensuring the reliable operation of the reinforced structure 2 and the original structure.

[0034] As a preferred embodiment, in step six, after removing the wall 14 at interface 15, if there is misalignment at the interface 15 of two adjacent unit structures 1, the unit structure 1 with the lower position is lifted to correct the misalignment.

[0035] Specifically, the lifting and correction of the relatively lower unit structure 1 includes: drilling a grouting hole 4 on the relatively lower unit structure 1 and at a position adjacent to the interface 15; and performing pressure grouting to the bottom of the unit structure 1 through the grouting hole 4, using the lifting force of the grout to lift the unit structure 1 to be flush with the adjacent unit structure 1.

[0036] In this embodiment, after the two unit structures 1 are connected at interface 15, if vertical misalignment is detected (i.e., one unit structure 1 settles relative to the other unit structure 1), the following method is used to lift and correct the unit structure 1 with the lower position: Using precision leveling instruments and total stations, accurately measure the elevation of the two unit structures 1 near interface 15 to determine the misalignment and the unit to be lifted (assumed to be unit structure 1A). Prepare equipment such as a high-pressure grouting pump, drilling rig, and grout mixer. The grout should preferably be a cement-based grout with good fluidity and high early strength. On the unit structure 1A to be lifted, drill one or more grouting holes 4 in the beam 12 area adjacent to interface 15. The drilling location should avoid the main reinforcing steel bars and embedded pipelines. The reinforcing structure 2 and its anchors 3 provide local reinforcement during the lifting process, ensuring the safety of the structure under the lifting force. Simultaneously, monitoring holes can be drilled at other key locations at the bottom of unit structure 1A to observe the grout flow. Install grouting sleeves in the grouting holes 4 and reliably connect them to the high-pressure grouting pump. Then start the grouting pump to inject the prepared grout into the foundation at the bottom of unit structure 1A at a controllable pressure and flow rate. The injected grout will diffuse at the bottom of unit structure 1A and form a grout cushion layer 72. With continuous grout injection, the resulting upward force will act evenly on the bottom of unit structure 1A. Real-time monitoring is essential during this process. Displacement sensors positioned on unit structure 1A and at interface 15 are used to monitor the lifting amount of the structure in real time. Strictly adhering to the principle of "small amounts, multiple times," the grouting pressure is gradually increased to ensure that unit structure 1A is lifted smoothly and slowly. When real-time monitoring data shows that the lifting amount of unit structure 1A has reached the predetermined value (i.e., the misalignment is eliminated and interface 15 is level), grouting is immediately stopped. Pressure is maintained for a period of time to allow the grout to further diffuse and initially solidify under the structure, ensuring a stable lifting effect. After the grout has completely solidified and reached the design strength, the grouting equipment is removed, and the grouting holes 4 and monitoring holes are sealed with high-strength concrete or mortar. Finally, the final installation or post-concrete pouring of the reinforcing structure 2 is completed according to design requirements, permanently binding the two unit structures 1 into one. This invention utilizes controllable pressure grouting technology to achieve millimeter-level precision leveling of large precast structures, effectively solving the misalignment problem at interface 15. The grouting holes 4 are positioned to avoid major load-bearing components, and the grouting and lifting process flexibly elevates the unit structure 1 without damaging it. The correction process fully utilizes the rigidity of the reinforcing structure 2, ensuring the safety of the local structure during lifting. After correction, the reinforcing structure 2 permanently improves the deformation resistance at interface 15.

[0037] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the invention without departing from the principles and spirit of the invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A method of advance construction of an underground structure of a reclamation project, characterized by, Includes the following steps: Step 1: Prefabrication of underground engineering unit structures: Based on the purpose, load and functional requirements of the underground engineering, the main structure is designed and divided into multiple unit structures. Each unit structure is prefabricated according to the design conditions and interfaces are reserved for docking and assembly. Step 2: Reinforce the underwater soft soil foundation of the designated area where underground engineering is to be constructed; Step 3: Float the unit structure from Step 1 to the designated area and sink it in the designated position for docking to form the main structure; Step 4: Fill the outside of the docked unit structure with boulders to form land. Step 5: Clean out and remove the packing material inside the unit structure; Step 6: Remove the wall at the interface to make the internal space of the two adjacent unit structures interconnected; Step 7: Construct the upper part of the underground structure.

2. The method according to claim 1, wherein In step one, the division method is determined according to the project type: for linear projects, the main structure is divided into multiple unit structures along its length, and interfaces are set between each unit structure through the connection between the beginning and end; for planar projects, the main structure is divided into multiple unit structures according to the spatial position of the unit structures in the main structure, and interfaces are set between each unit structure on at least one of the front, back, left, and right faces.

3. The method according to claim 1 or 2, wherein In step one, the unit structure is a hollow frame structure made of concrete, which includes various components such as columns, beams, slabs, and walls.

4. The method for prior construction of underground structures in land reclamation projects according to claim 3, characterized in that, The interface is located at the boundary of the unit structure and at the intersection of at least two types of components, including columns, beams, and walls.

5. The method for prior construction of underground structures in land reclamation projects according to claim 4, characterized in that, The interface is a concrete protrusion that protrudes inward from the surface of the unit structure body. In step three, when the unit structures are connected, the end faces of the interface abut against each other to provide initial positioning and support.

6. The method for prior construction of underground structures in land reclamation projects according to claim 1, characterized in that, In step six, after removing the wall at the interface, if there is misalignment at the interface of two adjacent unit structures, the unit structure with the lower position is raised to correct the misalignment.

7. The method for prior construction of underground structures in land reclamation projects according to claim 6, characterized in that, After lifting and correction, a reinforcing structure is installed at the interface between two adjacent unit structures.

8. The method for prior construction of underground structures in land reclamation projects according to claim 7, characterized in that, The reinforcing structure is a ring-shaped steel structure surrounding the interface. When uneven settlement occurs between two adjacent unit structures, the overall stiffness of the ring-shaped steel structure resists the slippage and opening at the interface, thereby limiting the relative displacement between the two adjacent unit structures.

9. The method for prior construction of underground structures in land reclamation projects according to claim 8, characterized in that, The annular steel structure is fixedly connected to the interface by multiple anchors, which are evenly distributed along the inner and outer edges of the annular steel structure.

10. The method for prior construction of underground structures in land reclamation projects according to claim 6, characterized in that, The process of lifting and correcting the relatively low-position unit structure specifically includes: drilling grouting holes on the relatively low-position unit structure and at a position adjacent to the interface; injecting pressure grout into the bottom of the unit structure through the grouting holes, and using the lifting force of the grout to lift the unit structure to be flush with the adjacent unit structure.

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