Construction method and structure of subsurface excavation underneath pass operation station construction transfer node

Abstract

The invention belongs to the field of underground traffic engineering, and relates to a construction method and structure for constructing a transfer node through an underground excavation underneath pass operation station. The newly-built station and the existing operation station are in T-shaped node transfer, when the existing operation station is constructed in the early stage, transfer nodes are implemented in different periods, and a plurality of supporting piles and supporting beams are reserved below a bottom plate in the range of the transfer nodes, so that the safety of the existing operation station is protected when the transfer nodes are subjected to underground excavation construction in the later stage. When a newly-built station adjoins an operation station, open excavation and sequential construction are carried out to complete a main body structure, fender posts within the height range of the operation station are broken, new and old structures are connected, fender posts within the negative three-layer range of a transfer node are broken, and underground excavation construction is carried out in a joint control mode of excavation face zoning and longitudinal step-by-step excavation to penetrate through the existing operation station. And the reserved pile foundation is broken according to needs, stable stress conversion is achieved, and the safety of an operation station above is ensured. According to the method, the construction risk can be effectively controlled, the safety of underground excavation and underneath crossing of the existing operation station is achieved, then the transfer function is achieved, and good economic benefits are obtained.

Description

Technical Field

[0001] This invention belongs to the field of underground transportation engineering, specifically relating to a construction method and structure for constructing a transfer node by tunneling under an operating station. Background Technology

[0002] Subway construction in various cities takes into account factors such as construction costs and urgency, adopting a phased construction approach for different lines. For transfer stations, it is common for stations belonging to different lines to be planned in different phases. Compared to passageway transfers, node transfers are more convenient, and T-shaped, L-shaped, and cross-shaped node transfers are preferred.

[0003] For transfer stations not constructed in the same phase, the common practice in the past was to construct the transfer node structure for future lines concurrently with the initial operational stations. In recent years, however, the approval process for subway construction plans in various regions has slowed down, and there are numerous cases of network planning adjustments optimizing or canceling some future lines. This inevitably leads to wasted investment in the transfer node structure for future lines. In areas with deep groundwater and strata suitable for tunnel construction, to avoid investment risks arising from uncertainties in later network adjustments and to reduce initial construction investment, it is no longer advisable to implement transfer nodes for future lines concurrently. Therefore, how to reserve conditions for tunnel construction of future lines in the most economical way is an urgent problem to be solved.

[0004] Furthermore, if the methods used in the construction of underground tunnels under the operating stations are not properly controlled when new lines are built and transfer nodes are implemented after the stations are put into operation, it will have an adverse impact on the operating stations and may even seriously endanger train operation safety. In order to reduce the risks, reasonable construction methods must be adopted.

[0005] In response to the above situation, a construction method and structure for constructing a transfer node at an operating station through a tunnel excavation that reserves conditions for future tunnel excavation construction of the railway line is proposed in the most economical and safe way, which has significant practical implications. Summary of the Invention

[0006] To overcome the problems existing in the prior art, this invention discloses a construction method and structure for constructing a transfer node by tunneling under an existing operating station. When constructing an existing operating station, the transfer node is not implemented in the early stages, and a temporary support system is reserved below the floor slab within the transfer node area. When constructing a new station adjacent to the existing operating station, the main structure is first completed by open-cut excavation, then the retaining piles within the height range of the existing operating station are removed to connect the old and new structures. Then, the retaining piles within the third basement level of the transfer node are removed. A controlled tunneling method is adopted, involving zoned excavation and longitudinal step-by-step excavation to tunnel under the existing operating station. The reserved temporary support system is removed as needed and converted into a permanent structural system, achieving a smooth transfer of stress and ensuring the safety of the operating station above. This invention effectively controls construction risks, realizes transfer functionality, and achieves good economic benefits.

[0007] To achieve the above objectives, the present invention provides a construction method for constructing a transfer node by tunneling under an operating station, comprising the following steps: S1: During the initial construction of the operating station, a temporary support system is reserved under the bottom slab within the transfer node area. The temporary support system includes several support piles and supporting beams reserved under the bottom slab, as well as retaining piles and pile cap beams reserved on both sides of the bottom slab in the cross-sectional direction. S2: During the construction of the new station, a partial slope will be made on the top slab area of ​​the operating station near the new station. After constructing a retaining wall above the top slab of the operating station, the soil will be backfilled. The concrete on the top of the shared retaining piles with the existing operating station will be removed, but the main reinforcement bars will be retained. A new cap beam will be constructed according to the design height of the new station's cap beam, and the retained main reinforcement bars of the shared retaining piles will be anchored into the new cap beam. S3: The main structure of the station is constructed by open excavation of the shield tunnel shaft of the new station. Specifically, the foundation pit of the shield tunnel shaft of the new station is excavated from top to bottom and the support is erected in a timely manner. After the foundation pit is excavated to the bottom, the main structure of the station is back-constructed from bottom to top. The main structure of the station includes a row of structural columns and beams of each floor slab constructed adjacent to the shared retaining piles of the new shield tunnel shaft. S4: Remove the shared retaining piles within the height range of the operating station at the transfer node, and construct the post-cast structure and expansion joints between the operating station and the newly built shield tunnel shaft. Specifically: construct the post-cast structure between the operating station and the newly built shield tunnel shaft. The post-cast structure includes the post-cast slab strips and side walls at each floor slab. Set expansion joints within the width range of the removed retaining piles. S5: Remove the retaining piles within the third basement level of the shield tunnel at the transfer node, and carry out a 1:1 soil slope along the longitudinal direction of the tunnel excavation to construct the bottom beam and column below the side wall of the operation station. S6: Excavate a certain thickness of top soil below the operating station floor. Preferably, excavate about 2m thick soil and install corbel supports on the outermost retaining pile cap beams on both sides. The corbels are connected to the cap beams and the operating station floor through pre-reserved connectors. S7: Along the cross-sectional direction of the cut-and-cover excavation, the intermediate soil is excavated in a basin shape. After the pile foundations of the corresponding support piles are removed, the longitudinal structural columns, bottom longitudinal beams and the local bottom plates on both sides of the intermediate position are constructed in sequence to achieve a smooth transition of the temporary support system to the permanent structural system. S8: Continue excavating the soil towards the retaining piles, and after removing the pile foundations of the corresponding support piles, construct longitudinal structural columns, bottom longitudinal beams and their respective partial bottom slabs, side walls and side wall buttress columns in sequence to achieve a smooth transition of the temporary support system to the permanent structural system. S9: After constructing the shield tunnel end wall and end wall buttress columns, carry out the post-cast structure construction of the third basement level between the operation station and the newly built shield tunnel shaft. The post-cast structure includes the post-cast slab strips on both sides of the expansion joint and the side walls of the third basement level. S10: Reinforce the shield tunnel end on one side of the operating station. After the shield tunnel enters below the operating station through the end wall, it will be air-propelled into the shield tunnel shaft of the new station and then hoisted out. Seal the post-cast slabs of each layer of the shield tunnel shaft of the new station and backfill the top slab with soil. Finally, use static cutting to break through the side wall of the first basement level of the operating station within the transfer node area to connect the operating station with the concourse level of the new station.

[0008] In one embodiment, the groundwater level at the station is deep, below the foundation slab of the new station, and the strata are suitable for tunneling under the operating station using the cut-and-cover method. The existing operating station is a two-story underground station, while the new station is a three-story underground station with a T-shaped transfer configuration. The retaining structure for both stations uses bored piles.

[0009] In one embodiment, throughout the entire construction process from S1 to S10, the existing operating station structure is automatically monitored and given tiered early warnings. Based on the deformation monitoring data, auxiliary control measures are taken in a timely manner.

[0010] In one embodiment, during step S1, the transfer node structure is not implemented synchronously during the initial construction of the operating station. On the one hand, several support piles and girders are reserved below the base slab, and the number and length of the support piles must meet the stress calculation requirements of the later excavation conditions. On the other hand, retaining piles and pile cap beams are reserved below the base slabs on both sides in the cross-sectional direction. The retaining piles are appropriately extended outward to meet the requirements of the shield tunnel passing through the station in the future and to allow for flexible fine-tuning of the line in the future. In addition, the girders and pile cap beams are physically close to the base slab of the operating station to facilitate load transfer.

[0011] In one embodiment, in step S2, within the transfer node range, the retaining piles on both sides of the existing operating station are designed and implemented in an inclusive manner according to the depth of the foundation pit of the future new line, so that the retaining piles can be shared when the new line is constructed adjacent to it.

[0012] In one embodiment, in step S3, to enhance the protection of the existing operating station, the first support is made of reinforced concrete, and the number of vertical supports and the spacing between the support planes within the shield shaft area are increased and strengthened.

[0013] In one embodiment, in step S4, the post-cast structures on both sides of the expansion joint are designed with equal thickness, and the width of the slab strip and side wall on any side is not less than 0.5m, so as to ensure the construction quality and waterproofing effect of the expansion joint.

[0014] In one embodiment, in step S6, the width of the corbel on the closely fitted base plate should not be less than 1.2m, the height should not be less than 0.6m, and the length in the longitudinal direction should be the same as that of the connected crown beam.

[0015] In one embodiment, in steps S7 and S8, the structure below the base plate of the operating station is divided into four longitudinal units along the cross-sectional direction, including two rows of longitudinal structures in the middle and two rows of longitudinal structures on both sides. The four longitudinal units are constructed sequentially, with the construction of the next unit carried out after the structural strength of the previous unit has reached 100%.

[0016] In one embodiment, in step S7, when constructing the two middle rows of longitudinal structures, first construct one row of longitudinal structural columns, bottom longitudinal beams, and the partial base plates on both sides of the middle position to achieve a smooth transition of the force from the temporary support system to the permanent structural system; then, following the same steps, construct the other row of longitudinal structural columns, bottom longitudinal beams, and the partial base plates on both sides of the middle position to achieve a smooth transition of the force from the temporary support system to the permanent structural system for the second time. In one embodiment, in step S8, when constructing two rows of longitudinal structures on both sides towards the retaining piles, the soil within the retaining pile area on one side is excavated, and the pile foundations of the corresponding support piles are removed. Then, the longitudinal structural columns, bottom longitudinal beams, and the partial base plates, side walls, and side wall buttress columns on one side are constructed to achieve a smooth transition of the load from the temporary support system to the permanent structural system for the third time. Then, following the same steps, the longitudinal structural columns, bottom longitudinal beams, and the partial base plates, side walls, and end wall buttress columns on the other side are constructed to achieve a smooth transition of the load from the temporary support system to the permanent structural system for the fourth time.

[0017] In one embodiment, in step S8, when connecting the base plate of the operating station to the newly built side wall below, the corbel is broken in sections to connect the side wall in sections.

[0018] In one embodiment, in step S8, the spans of the two side walls and the shield end wall are large in both directions, causing problems such as excessive reinforcement or calculation failure. Therefore, buttress columns are set inside the walls to improve the overall stress. The number of buttress columns is set according to the calculation.

[0019] The second objective of this invention is to provide a construction structure applicable to the above-mentioned method of tunneling under an operating station to construct a transfer node. During the initial construction of the existing operating station, a temporary support system is reserved below the floor slab within the transfer node area. When constructing a new station adjacent to the existing operating station, the reserved temporary support system is removed as needed during the tunneling construction under the existing operating station, and the temporary support system below the operating station floor slab is converted into a permanent structural system, thereby achieving a smooth transition of stress from a temporary structure to a permanent structure.

[0020] In one embodiment, the temporary support system includes support piles and supporting beams reserved below the operating station floor slab within the transfer node area, and retaining piles and pile cap beams reserved on both sides below the operating station floor slab in the cross-sectional direction of the transfer node.

[0021] In one embodiment, the temporary support system also includes retaining piles on both sides of the operating station within the transfer node range and corbel supports subsequently installed on the capping beams of the piles.

[0022] In one embodiment, the permanent structural system is the main structural system of the newly added transfer node, which includes the bottom crossbeam and column below the side wall of the operating station, longitudinal structural column, bottom slab and bottom longitudinal beam, side walls and side wall buttress columns, and end wall with opening and end wall buttress columns.

[0023] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows: When constructing existing operating stations in the early stages, the invention avoids implementing transfer nodes at different times, reserving only a few support piles and beams below the base slab within the transfer node area. When the new line is determined to be implemented, it adopts a cut-and-cover method to tunnel under the operating station, breaking the reserved pile foundations as needed, achieving a smooth transition of stress from temporary to permanent structures, effectively controlling construction risks, realizing transfer functions, and thus avoiding the investment waste risk caused by the uncertainty of network adjustments. For transfer nodes, it can reduce initial construction investment by more than 70%.

[0024] In addition, the inventive step evidence for the claims of this invention is also reflected in the following important aspects: 1. By adopting the construction method in this invention, it is possible to safely tunnel under the operating station, thereby realizing the transfer function. It can effectively control construction risks, avoid investment risks caused by the uncertainty of network adjustment, reduce initial construction investment, and achieve good economic benefits. It is expected to have huge commercial value after conversion.

[0025] 2. This invention is the first to propose a construction method for tunneling under existing operating stations to construct transfer nodes. It adopts a joint control method of dividing the excavation face into sections and longitudinally excavating in stages. It is also the first to propose the construction of supporting temporary and permanent structures, as well as a complete set of supporting construction processes, so as to achieve a smooth transition of stress from temporary to permanent structures, effectively control risks, and fill the technical gap in the industry at home and abroad.

[0026] 3. It was generally believed in the past that if the transfer nodes of the early construction stations were not implemented in the same phase, the transfer function could not be realized by tunneling through the operating station in the later stage. However, in this invention, by reserving appropriate temporary measures under the previous station and with the proposed complete set of construction methods, it is possible to safely tunnel under the station and realize the transfer function, thus solving a technical problem that people have long wanted to solve but have never been able to achieve. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure; Figure 1 A plan view of the pile foundation layout for the initial construction of the operation station; Figure 2 Sectional views of the enclosure of operating stations and newly built stations; Figure 3 Cross-sectional views of the operating station and the newly built station; Figure 4 For the cross section of the underground tunnel to pass through the operation station Figure 1 ; Figure 5 For the cross section of the underground tunnel to pass through the operation station Figure 2 ; Figure 6 For the cross section of the underground tunnel to pass through the operation station Figure 3 ; Figure 7 For the cross section of the underground tunnel to pass through the operation station Figure 4 ; Figure 8 For the cross section of the underground tunnel to pass through the operation station Figure 5 ; Figure 9 This is a plan view of the base structure of the transfer node.

[0028] In the diagram: 1. Support pile; 2. Support beam; 3. Cross-section retaining pile; 4. Pile top cap beam; 5. Retaining wall; 6. First common retaining pile; 6-1. Common retaining pile one; 6-2. Common retaining pile two; 6-3. Common retaining pile three; 7. New cap beam; 8. Support; 9. Inverted brace; 10. Structural column one; 11. Top slab crossbeam; 12. Middle slab crossbeam; 13. Bottom slab crossbeam one; 14. Top slab post-cast strip; 15-1. Middle slab post-cast strip one; 15-2. Middle slab post-cast strip two; 16-1. Post-cast side wall one; 16-2. Post-cast side wall two; 17. Expansion joint; 18. Bottom slab 19. Horizontal beam 2; 20. Structural column 2; 21. Corbel support; 21. Longitudinal structural column; 21-1. Longitudinal structural column 1; 21-2. Longitudinal structural column 2; 21-3. Longitudinal structural column 3; 21-4. Longitudinal structural column 4; 22. Bottom longitudinal beam; 22-1. Bottom longitudinal beam 1; 22-2. Bottom longitudinal beam 2; 22-3. Bottom longitudinal beam 3; 22-4. Bottom longitudinal beam 4; 23. Post-cast slab strip of the bottom plate; 24. Second common retaining pile; 25. Side wall 1; 26. Side wall buttress column 1; 27. Bottom plate; 28. Side wall 2; 29. ​​Side wall buttress column 2; 30. End wall; 31. End wall buttress column. Detailed Implementation

[0029] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] In this embodiment, the new station and the existing operating station form a T-shaped interchange node. During the initial construction of the existing operating station, the interchange node is not implemented in the same phase; only a few support piles and beams are reserved below the base slab within the interchange node area to protect the safety of the existing operating station during later underground excavation of the interchange node. When the new station is adjacent to the operating station, the main structure is first completed through open-cut excavation. Then, the retaining piles within the height range of the operating station are removed to connect the new and old structures. Next, the retaining piles within the third basement level of the interchange node are removed. A controlled underground excavation method is adopted, involving zoned excavation and longitudinal step-by-step excavation, to tunnel under the existing operating station. Reserved pile foundations are removed as needed to achieve a smooth transfer of stress. Under the premise of ensuring the safe operation of the operating station above, the underground tunnel under the existing operating station is safely excavated, thereby realizing the interchange function and achieving good economic benefits. Example 1

[0031] The specific implementation steps of a construction method for tunneling under an operating station to construct a transfer node are as follows: S1: During the initial construction of the operating station, several support piles 1 and supporting beams 2 are reserved below the base slab within the transfer node area. Cross-sectional retaining piles 3 and pile cap beams 4 are reserved below the base slabs on both sides in the cross-sectional direction. If the future line is confirmed for implementation, these reserved measures will serve as a temporary support structure system for the underground tunnel construction, ensuring the operational safety of the operating station above, and will also reduce the initial investment in the line. If the future line is adjusted or optimized and canceled, this most economical reserved condition method can avoid the investment waste caused by simultaneously implementing the transfer node structure of the future line in the early stages. Figure 1 As shown.

[0032] S2: During the construction of the new station, a partial slope will be created on the roof slab area of ​​the operating station near the new station. A retaining wall 5 will be constructed above the operating station's roof slab before backfilling. The top of the first shared retaining piles 6 (including shared retaining pile 1 6-1, shared retaining pile 2 6-2, and shared retaining pile 3 6-3 arranged sequentially from top to bottom) shared with the existing operating station will have its concrete removed, retaining the main reinforcement bars. A new crown beam 7 will be constructed according to the design height of the new station's crown beam, with the existing first shared retaining pile 6 reinforcement bars anchored into the new crown beam 7. For example... Figure 2 As shown.

[0033] S3: The new station's shield tunnel shaft will be excavated from top to bottom, and supports 8 and inverted supports 9 will be erected in a timely manner. Figure 2As shown, after the foundation pit is excavated to the bottom, the main structure of the station is constructed from bottom to top, including a row of structural columns-10, top slab beams-11, middle slab beams-12, and bottom slab beams-13, constructed adjacent to the shared retaining piles of the newly built shield shaft. Since the top slab beams and middle slab beams are adjacent to the main structure of the operating station, their horizontal stress is relatively small, mainly serving as edge beams for the initial drilling of the shield shaft. Compared to when they are not adjacent to the operating station, their horizontal dimensions and reinforcement can be significantly optimized. For example... Figure 3 As shown.

[0034] S4: Remove the shared retaining piles 6-1 within the height range of the operating station at the transfer node, and construct the post-cast structure between the operating station and the newly built shield tunnel shaft, including the top slab post-cast strip 14, the middle slab post-cast strip 15-1, the middle slab post-cast strip 2 15-2, and the post-cast sidewall 16-1 within the width range of the post-cast strips. Expansion joints 17 are set within the width range of the removed retaining piles to solve the problem of uneven settlement between the operating station and the newly built station. For example... Figure 2 As shown.

[0035] S5: Remove the shared retaining piles (36-3) within the third basement level of the shield tunnel at the transfer node, such as... Figure 2 As shown, a 1:1 slope is constructed along the longitudinal direction of the tunnel excavation. If necessary, temporary slope protection measures such as sprayed concrete can be added to ensure slope stability. Then, the bottom slab beam 2.18 and structural column 2.19 below the side wall of the operating station are constructed to support one side wall of the operating station. Figure 4 As shown.

[0036] S6: Excavate approximately 2 meters of soil beneath the operating station's foundation slab to provide construction space for installing corbel supports 20mm thick on the outermost retaining pile cap beams on both sides. Then, install the corbel supports, as follows: Figure 4 As shown. The corbel support connects the capping beam to the operating station floor slab via pre-installed connectors. The width of the corbel support close to the floor slab should not be less than 1.2m, and the height should not be less than 0.6m. Its length should be the same as the connected capping beam to ensure the stability of the retaining piles during subsequent underground excavation, thereby controlling construction risks. Figure 5 As shown.

[0037] S7: Excavate the intermediate soil in a basin-like manner along the cross-sectional direction of the cut-and-cover excavation. Remove the corresponding support piles from the bottom of the operating station's foundation slab to the bottom of the pit. Construct one row of longitudinal structural columns—21-1, the bottom longitudinal beam—22-1, and the partial foundation slabs 27 on both sides of the intermediate position. This achieves a smooth transition of the load-bearing structure from the temporary structure to the permanent structure. Subsequent construction will proceed after the structure reaches its design strength. Figure 5As shown. Following this procedure, earthwork excavation, demolition of the corresponding support piles 1, and construction of the other row of corresponding structures in the middle are carried out, including longitudinal structural column 21-2, bottom longitudinal beam 22-2, and the partial bottom plates 27 on both sides, to achieve a smooth transition of the second temporary structural system to the permanent structure, as shown. Figure 6 As shown.

[0038] S8: Excavate the soil within the retaining pile area on one side, remove the corresponding support pile foundations, and then construct the longitudinal structural column 321-3, the bottom longitudinal beam 32-3, and the partial bottom slab 27, side wall 25, and side wall buttress column 26 on both sides on one side. This achieves a smooth transition of the load-bearing structure from the third temporary structural system to the permanent structure. Figure 7 and Figure 9 As shown. Following this step, excavation of the soil on the other side and construction of the corresponding structures are carried out, including longitudinal structural column 4 21-4, bottom longitudinal beam 4 22-4 and its two sides' partial bottom slabs 27, side wall 2 28 and side wall buttress column 2 29, to achieve a smooth transfer of stress from the fourth temporary structural system to the permanent structure, as shown. Figure 8 and Figure 9 As shown. When connecting the base plate of the operation station to the newly built side wall below, the corbel should be broken in sections and the side wall should be connected in sections. It is recommended that the length of each section should not exceed 3m, so as to achieve a smooth transition of the stress from the fifth temporary structural system to the permanent structure.

[0039] Steps S7-S8 adopt a joint control method of excavation face zoning and longitudinal step-by-step excavation to gradually realize the smooth stress conversion of the temporary structure system to the permanent structure. This can effectively control construction risks and avoid investment risks caused by the uncertainty of network adjustment.

[0040] S9: Construct the shield tunnel end wall 30 and its end wall buttress columns 31 (e.g.) Figure 9 After that, the post-cast structure construction of the third basement level between the operation station and the newly built shield tunnel shaft will proceed, including the post-cast slab strip 23 on both sides of the expansion joint and the post-cast sidewall 16-2, as follows. Figure 3 As shown.

[0041] S10: Reinforce the shield tunneling end on one side of the operating station. After the shield enters below the operating station through the end wall, it will be air-propelled into the shield shaft of the new station and then hoisted out. Seal the post-cast slabs at the shield tunneling openings on each level of the new station's shield shaft, and backfill the top slab with soil. Finally, to minimize the impact of the demolition work on the operating station, static cutting will be used to break through the side wall of the first basement level of the operating station within the transfer node area, connecting the operating station with the concourse level of the new station to realize the transfer function. Example 2

[0042] A construction structure for the construction method of tunneling under the operation station to form a transfer node in Example 1 is provided. During the early construction of the existing operation station, several support piles 1 and supporting beams 2 are reserved below the bottom slab of the transfer node area. When tunneling under the existing operation station, the reserved pile foundations are broken as needed to achieve a smooth transition of stress from a temporary structural system to a permanent structural system, effectively control construction risks, realize the transfer function, avoid investment risks caused by the uncertainty of network adjustment, and reduce the initial construction investment.

[0043] The temporary structural system includes: first shared retaining piles 6 (including shared retaining pile 1 6-1, shared retaining pile 2 6-2, and shared retaining pile 3 6-3) and second shared retaining piles 24 set on both sides of the longitudinal direction of the operating station within the transfer node area; transverse retaining piles 3 and their pile top capping beams 4 set on both sides below the bottom slab of the operating station in the transverse direction within the transfer node area; support piles 1 and supporting beams 2 set below the bottom slab of the operating station; and corbel supports 20 subsequently installed on the pile top capping beams. Figure 1 and Figure 5 As shown.

[0044] The permanent structural system includes: structural column 219 and bottom beam 218 below the base plate of the operating station within the transfer node range; longitudinal structural column 21-1 and bottom longitudinal beam 22-1; longitudinal structural column 21-2 and bottom longitudinal beam 22-2; longitudinal structural column 31-3 and bottom longitudinal beam 32-3; longitudinal structural column 41-4 and bottom longitudinal beam 42-4; base plate 27; side wall 1 25 and side wall buttress column 1 26; side wall 2 28 and side wall buttress column 2 29; end wall 30 and end wall buttress column 31. The end wall 30 has two shield tunneling openings and a shield tunneling ring beam. Figure 9 As shown.

[0045] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A construction method for constructing a transfer node by tunneling under an operating station, characterized in that: Includes the following steps: S1: During the initial construction of the operating station, a temporary support system is reserved under the bottom slab within the transfer node area, including support piles and supporting beams, as well as retaining piles and pile cap beams on both sides of the bottom slab cross section. S2: When constructing a new station, remove the top concrete of the retaining piles shared with the operating station and retain the main reinforcement bars. Construct a new cap beam according to the height of the new station's cap beam, and anchor the retained main reinforcement bars into the new cap beam. S3: The main structure of the new station is constructed by open-cut tunneling of the shield shaft. S4: Remove the shared retaining piles within the height range of the operation station, and construct the post-cast structure and expansion joint between the operation station and the newly built shield tunnel shaft; S5: Remove the shared retaining piles within the height range of the third basement level of the shield tunnel shaft, and construct the bottom crossbeam and column below the side wall of the operation station; S6: Excavate a certain thickness of top soil below the base plate of the operation station and construct corbel support; S7: Excavate the intermediate soil in a basin shape along the cross section of the tunnel, remove the corresponding pile foundations, and then construct the longitudinal structural columns, bottom longitudinal beams and the local bottom slabs on both sides in sequence. S8: Continue excavating the soil towards the retaining piles, and after removing the corresponding pile foundations, construct longitudinal structural columns, bottom longitudinal beams and their respective partial bottom slabs, side walls and side wall buttress columns in sequence to achieve a smooth transition of the temporary support system to the permanent structural system. S9: Construct the shield tunnel end wall and end wall buttress columns, and construct the post-cast structure of the third basement level between the operation station and the newly built shield tunnel shaft; S10: Connects the operational station and the newly built station concourse level.

2. The construction method for constructing a transfer node by tunneling under an operating station according to claim 1, characterized in that: The station has a deep underground water level, which is lower than the bottom slab of the new station. The strata are suitable for the tunneling method to pass under the operating station. The operating station is a two-story underground station, while the new station is a three-story underground station with a T-shaped transfer system. The retaining structure uses bored piles.

3. The construction method for constructing a transfer node by tunneling under an operating station according to claim 1, characterized in that: In step S2, during the construction of the new station, a partial slope is made on the top slab area of ​​the operating station near the new station. After the retaining wall is constructed above the top slab of the operating station, the soil is backfilled. The concrete on the top of the retaining piles shared with the operating station is removed while the main reinforcement is retained. The new capping beam is constructed according to the design height of the new station capping beam, and the existing shared retaining pile reinforcement is anchored into the new capping beam.

4. The construction method for constructing a transfer node by tunneling under an operating station according to claim 1, characterized in that: In step S3, the foundation pit of the new station shield shaft is excavated from top to bottom and the support is erected in a timely manner. After the foundation pit is excavated to the bottom, the main structure of the station is back-constructed from bottom to top. The main structure of the station includes a row of structural columns and beams of each floor slab constructed at the location of the new shield shaft adjacent to the shared retaining piles.

5. The construction method for constructing a transfer node by tunneling under an operating station according to claim 1, characterized in that: In step S4, the retaining piles within the height range of the operating station at the transfer node are removed, and the post-cast structure between the operating station and the newly built shield tunnel shaft is constructed. This post-cast structure includes the post-cast slab strips and side walls at each floor slab, and expansion joints are set within the width range of the removed retaining piles.

6. The construction method for constructing a transfer node by tunneling under an operating station according to claim 1, characterized in that: In step S6, the top soil 2m thick below the bottom slab of the operation station is excavated, and corbel supports are installed on the outermost retaining pile cap beams on both sides. The corbels are connected to the cap beams and the bottom slab of the operation station through pre-reserved connectors.

7. The construction method for constructing a transfer node by tunneling under an operating station according to claim 1, characterized in that: In steps S7 and S8, the structure below the base plate of the operating station is divided into four longitudinal units along the cross-sectional direction, including two rows of longitudinal structures in the middle and two rows of longitudinal structures on both sides. The four longitudinal units are constructed in sequence, and the construction of the next unit is carried out after the strength of the previous unit reaches 100%.

8. The construction method for constructing a transfer node by tunneling under an operating station according to claim 7, characterized in that: In step S7, when constructing the two middle rows of longitudinal structures, first construct one row of longitudinal structural columns, bottom longitudinal beams, and the partial base plates on both sides of the middle position to achieve a smooth transition of the load from the temporary support system to the permanent structural system; then, following the same steps, construct the other row of longitudinal structural columns, bottom longitudinal beams, and the partial base plates on both sides of the middle position to achieve a smooth transition of the load from the temporary support system to the permanent structural system for the second time. In step S8, when constructing two rows of longitudinal structures on both sides towards the direction of the retaining piles, the soil within the area of ​​the retaining piles on one side is excavated, and the corresponding pile foundations are removed. Then, the longitudinal structural columns, bottom longitudinal beams, and the partial base plates, side walls, and side wall buttress columns on one side are constructed to achieve a smooth transition of the load from the temporary support system to the permanent structural system for the third time. Then, following the same steps, the longitudinal structural columns, bottom longitudinal beams, and the partial base plates, side walls, and side wall buttress columns on the other side are constructed to achieve a smooth transition of the load from the temporary support system to the permanent structural system for the fourth time. When connecting the operating station base plate to the newly built side wall below, the corbels are broken in sections and the side walls are connected in sections.

9. The construction method for constructing a transfer node by tunneling under an operating station according to claim 1, characterized in that: In step S10, the shield end of the operating station is reinforced. After the shield enters the area below the operating station through the end wall, it is pushed into the shield shaft of the new station by air and then hoisted out. The post-cast slabs of each layer of the shield shaft of the new station are sealed and the top slab is backfilled with soil. Finally, the side wall of the first basement level of the operating station within the transfer node area was removed by static cutting to connect the operating station with the concourse level of the newly built station.

10. A structure applicable to the construction method for constructing a transfer node by tunneling under an operating station as described in any one of claims 1 to 9, characterized in that: During the initial construction of the operating station, a temporary support system was reserved beneath the base slab of the transfer node area. When constructing a new station adjacent to the operating station, the tunnel was excavated to pass under the operating station, smoothly converting the temporary support system beneath the operating station's base slab into a permanent structural system. Specifically: The temporary support system includes support piles and supporting beams reserved under the base plate within the transfer node area, and retaining piles and pile cap beams reserved under the base plates on both sides in the cross section direction of the transfer node. The permanent structural system, which is the main structural system of the new transfer node, includes the bottom horizontal beams and columns below the side walls of the operating station, longitudinal structural columns, bottom slab and bottom longitudinal beams, side walls and side wall buttress columns, and end walls with openings and end wall buttress columns.

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