Construction method of longitudinal expansion of a subway station structure by the building-under-mine method
By using the step method for longitudinal expansion after the main structure of the open-cut station is poured, combined with the shotcrete and anchor construction method and composite lining structure, the problem that subway stations cannot be built in one go due to environmental constraints has been solved, achieving safe and economical construction results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA RAILWAY FIRST SURVEY & DESIGN INST GRP
- Filing Date
- 2023-09-06
- Publication Date
- 2026-07-14
AI Technical Summary
During the development of urban subway networks, subway stations are affected by the narrowness of existing roads and surrounding buildings and structures, making it impossible to construct them in one go using conventional open-cut or cut-and-cover methods. This results in difficulties in land acquisition and demolition, uncontrollable construction period, and large project investment.
After the main structure of the open-cut station was poured, the station structure was longitudinally expanded using the step method. The step method was used to reserve core soil for ring excavation, and the construction method was combined with shotcrete and anchor construction. A composite lining structure was adopted, including initial support, steel arch frame, steel mesh and shotcrete. The secondary lining was made of waterproof reinforced concrete, and support was provided by advanced self-advancing anchor bolts and sidewall self-advancing anchor bolts to ensure construction safety.
It has enabled safe construction of subway stations in complex environments, avoided large-scale land acquisition and demolition, reduced project investment, ensured the safety of the superstructure, and has high economic and social benefits.
Smart Images
Figure CN117248917B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of tunnel engineering technology, specifically relating to a construction method for longitudinally excavating a subway station structure using the mining method under a building. Background Technology
[0002] With the accelerating pace of urbanization and rapid economic development in my country, urban public transportation is facing increasing pressure. Subways, as a high-capacity mode of transportation, play a crucial role in alleviating urban traffic congestion. However, as the subway network continues to develop and improve, the construction environment for new subway lines is becoming increasingly complex. Subway stations are constrained by factors such as narrow existing roads and the influence of surrounding buildings and structures, making it impossible to construct them in one go using conventional cut-and-cover methods. To meet the technical requirements for subway station clearance, land acquisition and demolition are often considered, but coordination of land acquisition and resettlement is difficult, the construction period is uncontrollable, and the project investment is substantial. Furthermore, with the continuous densification of urban rail transit networks, situations where station structures are adjacent to buildings or have localized conflicts in plan view are becoming increasingly common. Summary of the Invention
[0003] To overcome the shortcomings of existing technologies, this invention provides a construction method for longitudinally expanding subway station structures using the mining method under buildings. After the main structure of the open-cut station is poured and reaches the design strength requirements, the station structure is longitudinally expanded using the step method, ensuring the safety of the construction of the longitudinally expanded station structure using the mining method and the safety of the superstructure.
[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0005] A construction method for longitudinally expanding the subway station structure under a building using the mining method is characterized in that: after the main structure of the station is poured and reaches the design strength requirements, the longitudinal entry retaining piles are removed, and the main structure of the station under the building is longitudinally expanded using the step method, wherein the step method is a ring excavation method with reserved core soil.
[0006] Includes the following steps:
[0007] Step 1: Level the site, drive the retaining piles for the open-cut main structure of the station, implement the skip pile construction, and construct the pile cap beam and retaining wall; drive dewatering wells along the outside of the pit for dewatering, excavate the pit for the open-cut main structure of the station, and erect internal supports while excavating until the bottom of the pit; spray concrete between the retaining piles of the open-cut main structure of the station, level the uneven parts with cement mortar, then construct the plain concrete cushion layer at the bottom of the pit, the fine stone concrete protective layer and the waterproof layer, pour the open-cut main structure of the station, and set up a vertical temporary support for the open-cut main structure at the interface between the open and covered excavations;
[0008] Step 2: After the main structure of the station is poured and reaches the design strength, the longitudinal tunnel retaining piles are removed, the initial support is excavated and constructed in a timely manner, the self-advancing anchor rods and locking anchor rods are installed on the side walls, the core soil is reserved in the ring excavation of each guide tunnel, and the step length is controlled at one tunnel diameter.
[0009] Step 3: Apply a waterproof layer, pour the bottom slab and part of the side walls in sections, ensuring that the bottom slab and side walls are in close contact with the initial support; remove the temporary invert arch in sections, apply a waterproof layer, pour the side walls and top slab, ensuring that the side walls and top slab are in close contact with the initial support; only after the side walls and top slab of this section have reached the design strength can the next section of temporary invert arch be removed and the secondary lining construction carried out. Vertical temporary supports are set in the cast-in-place C-shaped secondary lining structure; use lightweight concrete to backfill the gap between the top slab and the initial support, and pre-embed grouting pipes in the arch for subsequent supplementary grouting;
[0010] Step 4: After the C-shaped secondary lining structure reaches its design strength, the initial support at the cut-and-cover joint top slab and the retaining piles of the station's cut-and-cover main structure are longitudinally removed in sections. The steel reinforcement cut off from the initial support is welded to the steel reinforcement cut off from the retaining piles of the station's cut-and-cover main structure. The base layer is treated with sprayed concrete or cement mortar, and waterproofing is applied at the joint. The top slab connecting the cut-and-cover joint is then constructed. Only after the top slab connecting this section reaches its design strength can the initial support at the bottom slab connecting the cut-and-cover joint, the removal of the retaining piles of the station's cut-and-cover main structure, and the construction of the bottom slab connecting the cut-and-cover joint be carried out. Only after the top slab connecting the cut-and-cover joint and the bottom slab connecting the cut-and-cover joint are completed and reach their design strength can the vertical temporary supports one and two of the cut-and-cover main structure be removed in sections.
[0011] Furthermore, the stepped construction method adopts the shotcrete and anchor construction method, and the main structure of the station adopts a composite lining structure, including initial support, secondary lining and waterproof layer.
[0012] The initial support consists of a steel arch frame, steel mesh and shotcrete. The secondary lining uses waterproof reinforced concrete. The temporary invert arch uses a steel frame. The self-advancing anchor bolts for the advance support have an outer insertion angle of 10° to 15°, a circumferential and longitudinal spacing of 0.3m × 1.0m, and a range of 150° on the arch. Self-advancing anchor bolts are installed on the side walls facing the soil, with a circumferential and longitudinal spacing of 1.0m × 1.0m, arranged in a quincunx pattern.
[0013] Furthermore, an appropriate amount of micro-expansion agent is added to the lightweight concrete to compensate for concrete shrinkage and ensure that the gaps are filled densely.
[0014] Furthermore, a reinforcing beam is installed within the initial support, which is constructed promptly after the steel arch frame is erected. The reinforcing bars are anchored into the retaining piles of the open-cut main structure of the station, with an anchorage length of not less than 500mm. Grade A adhesive is used for the rebar installation, and the rebar should be welded to the reinforcing beam of the initial support.
[0015] Furthermore, the longitudinal excavation structure of the station is effectively connected to the open-cut main structure through steel bar connectors. The interface between the old and new concrete needs to be roughened to create a rough surface to improve adhesion. Then, epoxy resin adhesive is applied, and slow-expanding water-swelling sealant is installed and grouting steel pipes are pre-embedded. Micro-expansion cement grout is injected inside to ensure that the concrete at the interface between the old and new concrete is poured densely.
[0016] Furthermore, an additional waterproof layer is installed at the corner of the station structure. The waterproof membrane for the longitudinal excavation structure and the open-cut main structure of the station is made of polymer self-adhesive material with an overlap length of not less than 100mm. The overlap of the membrane is sealed with a continuous aluminum strip and nailed. The edges of the membrane are sealed with sealant.
[0017] Furthermore, since the initial support has an eccentric pressure problem, the longitudinal spacing of the steel arch frame and the circumferential spacing of the longitudinal connecting bars should be increased, and they should be arranged in a quincunx pattern on the inner and outer sides. If necessary, sandbags should be used to pile up the retaining piles of the open-cut main structure on the station side for counter-pressure.
[0018] Furthermore, at the locations where the longitudinal excavation structure and the open-cut main structure of the station are provided with vertical temporary supports, steel anchor plates should be pre-embedded. The anchor bars and the pre-embedded steel anchor plates should be welded by manual electric arc welding. After the exposed part of the pre-embedded steel anchor plate is derusted, it should be painted to prevent rust corrosion.
[0019] Furthermore, during the construction of the open-cut main structure, steel pipes were driven between the retaining piles of the open-cut main structure of the station and pre-grouting reinforcement was carried out. During the grouting reinforcement process, the pressure was mainly for filling, and the grouting pressure should not be too high to avoid damage to the building due to excessive grouting pressure.
[0020] The beneficial effects of this invention are:
[0021] 1) After the main structure of the open-cut station is poured and reaches the design strength requirements, the station structure is longitudinally expanded using the step method. During the pouring of the main structure of the open-cut station, a first vertical temporary support is set at the interface between the open and cut sections. The C-shaped secondary lining structure formed by longitudinal expansion and pouring using the mining method should also be set with a second vertical temporary support. The first vertical temporary support can be removed in sections after the construction of the connecting top plate and connecting bottom plate at the interface between the open and cut sections is completed and reaches the design strength, so as to ensure the safety of the construction of the longitudinal expansion of the station structure using the mining method and the safety of the superstructure.
[0022] 2) During the construction process of this invention, all materials and equipment used are conventional, and their corresponding dimensions are of conventional type, which is convenient for processing and manufacturing;
[0023] 3) This invention can ensure the structural safety and normal use of the longitudinal excavation structure in the mining method and the superstructure through the advanced support of the self-advancing anchor bolt. The longitudinal excavation station structure in the mining method solves the technical problem that conventional open-cut or cut-and-cover methods cannot be constructed in one go due to the limitations of the surrounding environment, and avoids a lot of land acquisition, demolition and resettlement work.
[0024] 4) This invention has high economic and social benefits and has broad application prospects in underground structure engineering such as urban rail transit, municipal roads, and civil buildings. Attached Figure Description
[0025] Figure 1 This is a plan layout of the main structure of a subway station longitudinally excavated using the mining method.
[0026] Figure 2 This is a cross-sectional layout diagram of the main structure of a subway station longitudinally excavated using the mining method.
[0027] Figure 3 Detailed drawings of the initial support reinforcement beam and rebar installation;
[0028] Figure 4 Detailed drawing of waterproofing for the interface between open and concealed excavation sections;
[0029] Figure 5 Detailed drawing of embedded parts for vertical temporary support structure slab;
[0030] Figure 6 Detailed drawing of steel anchor plate and anchor bar;
[0031] In the diagram, 1-Open-cut main structure, 2-Longitudinal tunnel retaining piles, 3-Building, 4-Station main structure, 5-Initial support, 6-Steel arch frame, 7-Temporary invert arch, 8-Advanced support self-advancing anchor bolt, 9-Lightweight concrete, 10-Sidewall self-advancing anchor bolt, 11-Vertical temporary support one for open-cut main structure, 12-Top slab connecting open-cut and cut-cut, 13-Bottom slab connecting open-cut and cut-cut, 14-Initial support reinforcing beam, 15-Rebar, 16-Retaining piles for open-cut main structure, 17-Rebar connector, 18-Slow-expanding water-swellable sealant, 19-Embedded grouting steel pipe, 20-Additional waterproof layer, 21-Waterproof membrane, 22-Aluminum strip, 23-Fixing nail, 24-Sealant, 25-Vertical temporary support two, 26-Embedded steel anchor plate, 27-Anchor bar. Detailed Implementation
[0032] The present invention will now be described in detail with reference to specific embodiments.
[0033] After the main structure of the open-cut station is poured and reaches the design strength requirements, the present invention adopts the step method (ring excavation with reserved core soil) to longitudinally expand the station structure; the step method is constructed using the shotcrete and anchor construction method, and the longitudinal expansion structure 4 of the station adopts a composite lining structure, including initial support 5, secondary lining and waterproof layer.
[0034] During the pouring of the main structure of the open-cut station, steel pipe temporary vertical supports are set at the interface between the open-cut and cut-out sections. The C-shaped secondary lining structure formed by longitudinal excavation and pouring using the mining method should also be equipped with steel pipe temporary vertical supports. The temporary vertical supports can only be removed in sections after the construction of the connecting top plate and connecting bottom plate at the interface between the open-cut and cut-out sections is completed and reaches the design strength, so as to ensure the safety of the construction of the shield shaft structure and the superstructure of the mining method.
[0035] This invention includes the following steps:
[0036] Step 1: Level the site, drive 16 retaining piles for the open-cut main structure of the station, perform staggered pile construction, and construct the pile cap beam and retaining wall, as follows. Figure 1 As shown; dewatering wells were drilled along the outside of the foundation pit for dewatering, the foundation pit of the open-cut main structure 1 of the station was excavated, and internal supports were erected while excavating until the bottom of the pit. The retaining piles of the open-cut main structure of the station were reinforced with shotcrete between the piles of 16, and cement mortar was used to level the uneven parts. Then, plain concrete cushion layer, fine stone concrete protective layer and waterproof layer were laid at the bottom of the pit. The open-cut main structure 1 of the station was poured. The vertical temporary support 11 of the open-cut main structure was set at the interface between the open and closed excavations.
[0037] Step 2: After the main structure 1 of the station is poured and reaches the design strength, the longitudinal tunnel retaining piles 2 are broken, the initial support 5 is excavated and constructed in a timely manner, the self-advancing anchor rods 10 and the locking anchor rods are installed on the side walls, the core soil is reserved in the ring excavation of each guide tunnel, and the step length is controlled at one tunnel diameter.
[0038] The initial support 5 consists of a steel arch frame 6, steel mesh and shotcrete. The secondary lining uses a reinforced concrete structure. The temporary invert arch 7 uses a steel frame. The advanced support self-advancing anchor bolts 8 have an external insertion angle of 10° to 15°, a circumferential and longitudinal spacing of 0.3m × 1.0m, and a range of 150° from the arch. Self-advancing anchor bolts 10 are installed on the side wall facing the soil, with a circumferential and longitudinal spacing of 1.0m × 1.0m, arranged in a quincunx pattern.
[0039] like Figure 3 As shown, a reinforcing beam 14 is installed in the initial support 5. It is installed in a timely manner after the steel arch frame 6 is erected. The reinforcing bar 15 is anchored into the retaining pile 16 of the open-cut main structure of the station. The anchoring length should not be less than 500mm. Grade A glue is used for the rebar installation. The reinforcing bar 15 should be welded to the reinforcing bar 14 of the initial support 5.
[0040] The initial support 5 has an eccentric pressure problem. The longitudinal spacing of the steel arch frame 6 and the circumferential spacing of the longitudinal connecting bars should be increased. They should be arranged in a quincunx pattern on the inner and outer sides. If necessary, sandbags should be piled up on the station side of the retaining pile 16 for counter-pressure.
[0041] Step 3: Apply a waterproof layer, pour the bottom slab and part of the side walls in sections, ensuring that the bottom slab and side walls are in close contact with the initial support 5; remove the temporary invert arch 7 in sections, apply a waterproof layer, pour the side walls and top slab, ensuring that the side walls and top slab are in close contact with the initial support 5; only after the side walls and top slab of this section have reached the design strength can the next section of temporary invert arch 7 be removed and the secondary lining construction carried out. Vertical temporary supports 25 are set in the cast-in-place C-shaped secondary lining structure; use lightweight concrete 9 to backfill the gap between the top slab and the initial support 5, and pre-embed grouting pipes in the arch for subsequent grouting;
[0042] Add an appropriate amount of micro-expansion agent to plain concrete to compensate for concrete shrinkage and ensure that the gaps are filled tightly.
[0043] Step 4: After the C-shaped secondary lining structure reaches its design strength, the initial support 5 at the cut-and-cover joint top slab and the retaining piles 16 of the station's cut-and-cover main structure are longitudinally removed in sections. The steel arch frame 6 cut off the reinforcing bars on the initial support 5 is welded to the steel bars cut off the retaining piles 16 of the station's cut-and-cover main structure. After the base layer is treated with sprayed concrete or cement mortar, waterproofing is applied to the joint. The connecting top slab 12 at the cut-and-cover joint is then constructed. Only after the connecting top slab reaches its design strength can the initial support 5 at the cut-and-cover joint bottom slab 13, the retaining piles 16 of the station's cut-and-cover main structure, and the connecting bottom slab 13 at the cut-and-cover joint be constructed. Only after the cut-and-cover joint top slab 12 and the cut-and-cover joint bottom slab 13 are completed and reach their design strength can the vertical temporary support 11 and the vertical temporary support 25 of the cut-and-cover main structure be removed in sections.
[0044] The longitudinal excavation structure 4 of the station is effectively connected to the open-cut main structure 1 through the steel bar connector 17. The interface between the old and new concrete needs to be roughened to form a rough surface to improve adhesion. Then, epoxy resin adhesive is poured and slow-expanding water-swelling sealant 18 is installed and grouting steel pipe 19 is pre-embedded. Micro-expansion cement grout is injected inside to ensure that the concrete at the interface between the old and new concrete is poured densely.
[0045] like Figure 4 As shown, an additional waterproof layer 20 is installed at the corner of the station structure. The waterproof membrane 21 of the longitudinal excavation structure 4 and the open-cut main structure 1 of the station is made of polymer self-adhesive material with an overlap length of not less than 100mm. The overlap of the membrane is sealed with a continuous aluminum strip 22 and nailed 23. The membrane is sealed with sealant 24.
[0046] like Figure 5 , 6As shown, at the location where the longitudinal excavation structure 4 of the station is connected to the open-cut main structure 1, where vertical temporary supports are provided, Q235B steel anchor plates 26 should be pre-embedded. The anchor bars 27 and the pre-embedded steel anchor plates 26 are welded by manual electric arc welding. The exposed part of the pre-embedded steel anchor plates 26 is derusted and then coated with paint to prevent rust corrosion.
[0047] like Figure 2 As shown, during the construction of the open-cut main structure 1, steel pipes 28 were installed between the retaining piles 16 of the open-cut main structure of the station, and pre-grouting 29 was carried out for reinforcement. During the grouting reinforcement process, the pressure was mainly for filling, and the grouting pressure should not be too high to avoid damage to the building 3 due to excessive grouting pressure.
[0048] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0049] The content of this invention is not limited to the embodiments listed. Any equivalent modifications made by those skilled in the art to the technical solutions of this invention by reading this specification are covered by the claims of this invention.
Claims
1. A construction method for a subway station structure using the underground mining method with longitudinal excavation, characterized in that: After the main structure (1) of the station is poured and reaches the design strength requirements, the longitudinal tunnel retaining piles (2) are broken, and the main structure (4) of the station under the building (3) is longitudinally expanded using the step method. The step method is a ring excavation method with reserved core soil. Includes the following steps: Step 1: Level the site, drive the retaining piles (16) of the station's open-cut main structure, perform pile skipping construction, construct the pile top cap beam and retaining wall; drive dewatering wells along the outside of the pit for dewatering, excavate the pit of the station's open-cut main structure (1), and erect internal supports while excavating until the bottom of the pit, spray concrete between the retaining piles (16) of the station's open-cut main structure, level the uneven parts with cement mortar, then construct the plain concrete cushion layer at the bottom of the pit, the fine stone concrete protective layer and the waterproof layer, pour the station's open-cut main structure (1), and set up a vertical temporary support (11) for the open-cut main structure at the interface of the open and dark excavation. Step 2: After the main structure (1) of the station is poured and reaches the design strength, the longitudinal tunnel retaining piles (2) are broken, the initial support (5) is excavated and the side wall self-advancing anchors (10) and locking anchors are installed. The core soil is reserved in the ring excavation of each guide tunnel, and the step length is controlled at one tunnel diameter. Step 3: Apply a waterproof layer, pour the bottom slab and part of the side walls in sections, and ensure that the bottom slab and side walls are in close contact with the initial support (5); remove the temporary invert arch (7) in sections, apply a waterproof layer, pour the side walls and top slab, and ensure that the side walls and top slab are in close contact with the initial support (5); after the side walls and top slab of this section reach the design strength, the next section of temporary invert arch (7) can be removed and the secondary lining construction can be carried out. Set the second vertical temporary support (25) in the cast-in-place C-shaped secondary lining structure; use lightweight concrete (9) to backfill the gap between the top slab and the initial support (5), and pre-embed grouting pipes in the arch for subsequent grouting; Step 4: After the C-shaped secondary lining structure has reached the design strength, the initial support (5) at the top plate of the open-cut and cut-out interface and the retaining piles (16) of the main structure of the open-cut station are removed in sections longitudinally. The steel bars cut off by the steel arch frame (6) on the initial support (5) are welded to the steel bars cut off by the retaining piles (16) of the main structure of the open-cut station. After the base layer is treated with sprayed concrete or cement mortar, waterproofing is applied at the interface. The top plate (12) connecting the open-cut and cut-out interface is constructed. After the top plate of this section reaches the design strength, the initial support (5) at the bottom plate (13) connecting the open-cut and cut-out interface, the retaining piles (16) of the main structure of the open-cut station, and the bottom plate (13) connecting the open-cut and cut-out interface can be removed in sections. After the top plate (12) connecting the open-cut and cut-out interface and the bottom plate (13) connecting the open-cut and cut-out interface are completed and reach the design strength, the first vertical temporary support (11) and the second vertical temporary support (25) of the main structure of the open-cut can be removed in sections. The step method is constructed using the sprayed anchor construction method. The main structure of the station (4) adopts a composite lining structure, including initial support (5), secondary lining and waterproof layer. The initial support (5) consists of a steel arch frame (6), steel mesh and shotcrete. The secondary lining uses waterproof reinforced concrete. The temporary invert arch (7) uses a steel frame. The self-advancing anchor rod (8) of the advance support has an external insertion angle of 10° to 15°, a ring and longitudinal spacing of 0.3m × 1.0m, and a range of 150° for the arch. The side wall of the soil-facing side wall is equipped with a side wall self-advancing anchor rod (10), with a ring and longitudinal spacing of 1.0m × 1.0m, arranged in a quincunx pattern.
2. The construction method for a subway station structure using the underground mining method according to claim 1, characterized in that: The lightweight concrete (9) incorporates an appropriate amount of micro-expansion agent to compensate for concrete shrinkage and ensure that the gaps are filled densely.
3. The construction method for a subway station structure using the underground mining method according to claim 2, characterized in that: The initial support (5) is equipped with a reinforcing beam (14), which is installed in a timely manner after the steel arch frame (6) is erected. The reinforcing bars (15) are anchored into the retaining piles (16) of the open-cut main structure of the station. The anchoring length should not be less than 500mm. Grade A glue is used for the reinforcing bars. The reinforcing bars (15) should be welded to the reinforcing bars of the initial support (5) reinforcing beam (14).
4. The construction method for a subway station structure using the underground mining method according to claim 3, characterized in that: The main structure of the station (4) and the open-cut main structure (1) are effectively connected by a steel bar connector (17). The interface between the old and new concrete needs to be roughened to form a rough surface to improve adhesion. Then, epoxy resin adhesive is poured and a slow-expanding water-swelling sealant (18) is installed and a grouting steel pipe (19) is pre-embedded. Micro-expansion cement slurry is injected inside to ensure that the concrete at the interface between the old and new concrete is poured densely.
5. The construction method for a subway station structure using the underground mining method according to claim 4, characterized in that: An additional waterproof layer (20) is installed at the corner of the station structure. The waterproof membrane (21) of the main structure (4) of the station and the open-cut main structure (1) is made of polymer self-adhesive material with an overlap length of not less than 100mm. The overlap of the membrane is sealed with a continuous aluminum strip (22) and nailed (23). The membrane is sealed with sealant (24).
6. The construction method for a subway station structure using the underground mining method according to claim 1, characterized in that: The initial support (5) has a problem of bias pressure. The longitudinal spacing of the steel arch frame (6) and the circumferential spacing of the longitudinal connecting bars should be increased. The steel arch frame (6) should be arranged in a plum blossom pattern on the inner and outer sides. The retaining piles (16) of the open-cut main structure should be reinforced with sandbags on the station side for counter-pressure.
7. The construction method for a subway station structure using the underground mining method according to claim 1, characterized in that: At the location where the main structure (4) of the station and the open-cut main structure (1) are provided with vertical temporary supports, steel anchor plates (26) should be pre-embedded. The anchor bars (27) and the pre-embedded steel anchor plates (26) are welded by manual electric arc welding. The exposed part of the pre-embedded steel anchor plates (26) is derusted and then coated with paint to prevent rust corrosion.
8. The construction method for a subway station structure using the underground mining method according to claim 1, characterized in that: During the construction of the open-cut main structure (1), steel pipes (28) were installed between the retaining piles (16) of the open-cut main structure of the station, and pre-grouting (29) was carried out for reinforcement. During the grouting reinforcement process, the pressure was mainly for filling, and the grouting pressure should not be too high to avoid the building (3) being damaged due to excessive grouting pressure.