Construction method of combined structure system of metro open-cut section and underpass tunnel

Abstract

The present application relates to a kind of construction method of metro open cut section and tunnel construction structure system, comprising the following steps: pile wall construction;In turn excavate foundation pit, construction crown beam and reinforced concrete support, set up two layers of steel pipe support, construction lower foundation pit enclosure structure;By sliding rail segmented propulsion construction;Construction in plate;Construction top plate.The beneficial effects of the present application are: using the way of overlapping construction, save space resources and construction cost, single box multi-chamber multilayer frame tunnel main structure is based on the principle of "vertical layering, horizontal segmentation, layer by layer from bottom to top parallel order construction", conducive to the smooth development of main structure process;Upper intermediate pipeline corridor and lower metro section partition wall are provided with hidden beam, which improves the overall stress effect of structure;Tunnel lower foundation pit uses cohesive soil backfilling, forms stable filler layer, reduces the damage of structure caused by uneven settlement of filler.

Description

Technical Field

[0001] This invention belongs to the field of multi-chamber, multi-layer frame tunnel technology, and particularly relates to a construction method for a combined structure system of open-cut subway sections and underpass tunnels. Background Technology

[0002] With the rapid development of urban subways and the continuous improvement of subway networks in urban rail transit, complex construction problems inevitably arise in the engineering construction of numerous nodes within the subway network, such as parallel, overlapping, and intersecting sections between open-cut sections and underpasses. In projects crossing existing or planned tunnels, the excavation of subway open-cut sections will inevitably affect the existing or planned tunnel structures. For example, soil disturbance caused by construction between the subway open-cut section and the existing or planned tunnel can lead to ground settlement or uplift, which will affect the construction and even the safety of the structures. Therefore, ensuring the safe operation of subway open-cut sections and existing or planned tunnels is a key issue that needs to be considered in engineering construction.

[0003] In response to the complex construction conditions where the open-cut section and the underpass tunnel are parallel, overlapping, and intersecting, the common approach both domestically and internationally is to design the subway tunnel and the underpass tunnel separately and construct them in phases, or to place the subway tunnel on both sides of the underpass tunnel or under the existing tunnel. However, this approach has the disadvantages of wasting space resources and construction costs.

[0004] In view of this, there is an urgent need to invent a "top-bottom overlapping" combined subway tunnel and underpass tunnel, which can effectively solve the problems of traditional design, save space resources and construction costs, has a broad application prospect, high practical value, and high technical and social benefits. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a construction method for a combined structure system of open-cut sections and underpass tunnels in subways.

[0006] The construction method for this type of subway open-cut section and underpass tunnel combined structure system includes the following steps:

[0007] S1. Pile wall construction: The steel cage of the bored interlocking pile is precisely fixed using a flat plate locator, and the longitudinal reinforcement is connected by a straight threaded sleeve connection; bored interlocking piles are drilled around the foundation pit to form a pile wall;

[0008] S2. Excavate the foundation pit and construct the capping beam and reinforced concrete support at the top of the pile wall; continue to excavate the foundation pit and set two layers of steel pipe support between the pile walls through movable steel support plates to form the upper foundation pit retaining structure; continue to excavate the foundation pit with slope and construct the lower foundation pit retaining structure.

[0009] S3. Pour the bottom slab at the bottom of the foundation pit, and use a high-precision intelligent wall formwork system to fix the wall formwork of the side walls and central partition walls of the subway tunnel section. Then stabilize the tie rods; pour concrete in sections and advance the construction in sections using sliding rails.

[0010] S4. Construct intermediate slabs on the top of the side walls and central partition walls of the subway tunnel section, and pre-embed hidden beams;

[0011] S5. Complete the construction of the municipal tunnel sidewalls and central partition walls using the same method as in step S3, and then construct the roof slab.

[0012] Preferably, in step S1: the flat plate locator is welded to the moving plate of the rolling welding machine; when welding the reinforcing cage of the drilled interlocking pile, the longitudinal bars in the reinforcing cage are welded to the flat plate locator; and straight threaded sleeves are lapped between the longitudinal bars of different sections of the reinforcing cage.

[0013] Preferably, in step S2: the reinforced concrete support is connected to the top of the pile wall through the capping beam to form the first horizontal support; the two layers of steel pipe support are connected to the pile wall cofferdam through movable steel support hanging plates to form the second and third horizontal supports.

[0014] Preferably, in step S2: the movable steel support hanging plate includes a steel hook, a hanging plate, stiffening ribs, and a steel plate base support. The steel hook is welded to the upper end of the hanging plate through a through-hole plug, and the movable steel support hanging plate is hung on the pile wall cofferdam through the steel hook. The bottom of the hanging plate is welded to a steel plate base support for supporting the end of the steel pipe. Stiffening ribs are welded to both ends of the steel plate base support, and the stiffening ribs are also welded to the hanging plate.

[0015] Preferably, in step S2: the foundation pit below the upper foundation pit retaining structure is excavated by slope excavation, and a concrete platform is provided on the inner side of the pile wall. The lower foundation pit retaining structure includes anchor rods, prestressed anchor cables and a steel mesh sprayed surface layer. The anchor rods are fixed on the excavation slope of the foundation pit where the subway tunnel is located; the prestressed anchor cables are fixed on the concrete platform.

[0016] As a preferred option, in step S3: first, check the geological conditions at the bottom of the foundation pit, then carry out the construction of the foundation slab cushion layer, waterproof layer and waterproof protective layer; carry out the binding of the foundation slab reinforcement and concrete pouring, and after the foundation slab concrete has cured to the specified strength, remove the supporting formwork of the foundation slab.

[0017] Preferably, the high-precision intelligent adjustable wall formwork system includes an L-shaped steel formwork, tie rods, stiffening plates, bolts, a horizontal adjusting rail, a hydraulic device, a sliding platform, and a slide rail. The L-shaped steel formwork is fixed to the hydraulic device by bolts. The tie rods are installed between the L-shaped steel formworks to connect the two sides of the L-shaped steel formwork. The stiffening plates are welded to the horizontal plate of the L-shaped steel formwork. The hydraulic device is installed on the sliding platform to realize the vertical lifting and lowering of the steel formwork. A horizontal adjusting rail is provided on the sliding platform, and the hydraulic device moves horizontally along the horizontal adjusting rail. The sliding platform is installed on the slide rail, and the sliding platform moves longitudinally along the slide rail.

[0018] As a preferred option, in step S3: the reinforcing bars of the side walls and central partition walls of the subway tunnel are tied. After the tying is completed, the high-precision intelligent adjustable wall formwork system is moved to the construction position. The L-shaped steel formwork is fixed at the construction requirements by adjusting the hydraulic device and the horizontal adjustment rail. Then, tie rods are installed to fix the two L-shaped steel formworks together. After all the formwork is fixed, concrete is poured in sections, with each section being a pouring cycle. After the concrete of the side walls and central partition walls has cured, the formwork is demolded. Finally, the sliding platform is moved forward by the slide rail to carry out the construction of the next section.

[0019] As a preferred option, in step S5, when the side walls and central partition walls of the municipal tunnel are poured in sections, the movable steel support plates and steel pipe supports are removed accordingly.

[0020] This combined open-cut subway section and underpass tunnel structure system is obtained by any of the methods described above.

[0021] The beneficial effects of this invention are:

[0022] 1) The subway open-cut section and the municipal underpass tunnel are built together by overlapping and building in a way that saves space resources and construction costs. The main structure of the single-box multi-room multi-layer frame tunnel is based on the principle of "vertical layering, horizontal segmentation, and parallel construction from bottom to top layer by layer", which is conducive to the smooth progress of the main structure construction process.

[0023] 2) A hidden beam is installed between the upper intermediate pipeline corridor and the partition wall of the lower subway section, which improves the overall structural stress effect; the foundation pit at the bottom of the tunnel is backfilled with cohesive soil to form a stable filling layer and reduce structural damage caused by uneven settlement of the filling material.

[0024] 3) The construction formwork support adopts a high-precision intelligent adjustable wall formwork system and a cup-lock type support to realize standardized construction of the project, reduce the difficulty and workload of construction, greatly improve the construction efficiency of the project, avoid the occurrence of engineering disasters, and save project costs; at the same time, the L-shaped steel formwork and hydraulic adjustment device ensure the verticality requirements of the side wall construction.

[0025] 4) The upper foundation pit support adopts a hybrid support system of "reinforced concrete support + steel pipe support". The lower foundation pit adopts sloping excavation and is reinforced by anchor bolts + anchor cables + steel mesh spraying surface layer. Compared with full-section wide excavation, it greatly reduces the amount of foundation pit excavation and backfilling work, shortens the construction time, avoids the cost increase caused by using internal support in the lower foundation pit, and the narrow sloping excavation is conducive to the stability of the foundation pit.

[0026] 5) For reinforced interlocking piles, the use of a flat plate locator for constructing the steel cage can control the thread spacing, installation torque, external thread leakage, and go / no-go gauge issues in advance. The steel cage fabrication and construction has a high first-time pass rate, reducing construction time and material costs.

[0027] 6) At the connection between the steel support and the steel waler, a new type of movable steel support hanging plate is used, which makes the installation and disassembly of the steel support flexible and quick, improves construction efficiency, and eliminates the situation where the elevation deviation at both ends of the steel support is large and the axial force is difficult to apply after the steel support is erected. At the same time, the requirements for the flatness and verticality of the cap beam surface and the elevation deviation of the cap beam on both sides are low, which ensures the installation quality of the steel support, improves the erection efficiency of the steel support, and speeds up the construction progress. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of an overlapping and combined structural system;

[0029] Figure 2 This is a schematic diagram of the enclosure structure system in this invention;

[0030] Figure 3 This is a schematic diagram of a high-precision intelligent adjustable wall mold system;

[0031] Figure 4 This is a front view of the new type of movable steel support hanging plate;

[0032] Figure 5 This is a side view of the new type of movable steel support hanging plate;

[0033] Figure 6 This is a schematic diagram of a flatbed locator.

[0034] The following are the labeling instructions in the diagram: 1. Base plate; 2. Middle plate; 3. Top plate; 4. Central partition wall; 5. Side wall; 6. Hidden beam; 7. Municipal tunnel; 8. Subway tunnel section; 9. L-shaped steel formwork; 10. Tie rod; 11. Stiffening plate; 12. Bolt; 13. Horizontal adjustment rail; 14. Hydraulic device; 15. Sliding platform; 16. Slide rail; 17. Drilled interlocking pile; 18. Reinforced concrete support; 19. Crown beam; 20. Steel pipe support; 21. Prestressed anchor cable; 22. Anchor rod; 23. Concrete platform; 24. Longitudinal reinforcement; 25. Stirrup; 26. Straight threaded sleeve; 27. Flat plate positioner; 28. Steel plate base support; 29. ​​Stiffening rib; 30. Hanging plate; 31. Steel hook. Detailed Implementation

[0035] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0036] Example 1

[0037] As one example, the construction method for this combined open-cut section and underpass tunnel structure of a subway includes the following steps:

[0038] S1. Level the site and inspect the equipment installation and commissioning work;

[0039] Precast steel cage: The precast steel cage is hoisted and connected in sections. The steel cage is precisely fixed using a flat plate locator 27. The longitudinal bars 24 are connected using straight threaded sleeves 26. The flat plate locator 27 is welded to the moving plate of the roll welding machine and pre-connected to each longitudinal bar 24. The connection is checked, and any defects such as thread length and thread spacing are rectified immediately. Then, from the placement of the longitudinal bars 24 until the roll welding of the steel cage is completed, the steel cage is transported in sections after roll welding, and the relative position of each longitudinal bar 24 is controlled throughout the process.

[0040] Plain concrete pile construction: Drilling is carried out using a rotary drilling rig, with steel casing for wall protection. After the hole is formed, concrete is poured in and cured until final set.

[0041] Reinforced concrete pile construction: After the plain pile concrete has set, a full casing drilling rig is used to cut the concrete of the intersecting part of the adjacent plain piles to achieve interlocking construction of reinforced concrete piles.

[0042] S2. Excavate the soil above the 18th elevation of the reinforced concrete support in the foundation pit, and construct the capping beam 19 and the first reinforced concrete support 118.

[0043] Continue excavating the foundation pit and construct the second and third steel pipe supports. The steel pipe supports are connected to the pile wall steel cofferdam through a new type of movable steel support hanging plate.

[0044] The lower part of the foundation pit is excavated with a slope, supported by anchor bolts 22 and prestressed anchor cables 21, and steel mesh is laid on the slope and sprayed with a top layer.

[0045] Check the geological conditions of the foundation and whether the soil quality matches the design. Have the relevant unit conduct an inspection of the foundation pit. Construction can only continue after the inspection is passed.

[0046] During actual construction, when the excavation of the foundation pit approaches 0.2m above the design elevation of the foundation, manual cleaning should be carried out to prevent over-excavation or disturbance of the foundation soil. The foundation should be flat and compacted, with allowable deviations of: elevation +10 / -20mm; flatness 20mm, and no more than one deviation within a 1m range.

[0047] The main structure of the foundation pit is constructed using the sequential construction method, consistent with the excavation sequence. Depending on the pit conditions and construction organization, excavation is carried out in layers using a stepped excavation method, either from the higher or lower mileage end. The excavation steps are 3–6 meters long, with a longitudinal slope of 1:3 and a transverse counterweight slope of 1:1. To control construction joints, each construction step is limited to approximately 25 meters in length, with segmentation locations considered at 1 / 3 to 1 / 4 of the structural span, avoiding pre-reserved openings, partition walls, and other similar locations as much as possible.

[0048] Dry drilling is required for anchor bolt 22; water drilling is prohibited to ensure that the construction of anchor bolt 22 does not worsen the engineering geological conditions of the slope rock mass and to guarantee the bonding performance of the borehole wall. The drilling speed must be strictly controlled according to the performance of the drilling rig and the anchoring strata to prevent borehole twisting and diameter changes. The anchor bolt 22 body adopts... 25mm threaded steel bars, four bars are used for anchoring. A 25mm steel bar is welded to the end of anchor rod 22; the tail end of anchor rod 22 is treated with cement slurry for corrosion protection.

[0049] The anchor cables are cut and bundled on-site simultaneously with drilling. The inner anchoring section is corrugated, while the tensioning section is straight. The outer surface of the anchor cable body is... Ten 60mm steel pipe supports are distributed. 15.2mm steel strand, internally used 8. Rebar fixing A ring of 60mm steel pipes is used. The anchor cables are made of high-strength, low-relaxation steel. 15.2mm steel strand, strength 1860Mpa. A positioning bracket is installed every 2.0m along the anchor cable axis to ensure that the anchor cable has a sufficient protective layer.

[0050] S3, Construction of base slab 1 cushion layer, waterproof layer and waterproof protective layer;

[0051] The reinforcement of the base slab 1 is tied and the concrete is poured. After the concrete of the base slab 1 has cured to the specified strength, the supporting formwork of the base slab 1 is removed.

[0052] The steel reinforcement of the side walls 5 and the central partition wall 4 of the subway tunnel section 8 is tied. After the tying is completed, the high-precision intelligent adjustable wall formwork system is moved to the construction position. The wall formwork is fixed at the construction requirements by adjusting the hydraulic device 14 and the horizontal adjustment rail 13. Then, the tie rods 10 in the wall formwork system are installed to stabilize the overall structure. After all the formwork is fixed, concrete is poured. Every 25m is a pouring cycle. After the concrete has cured, the formwork is demolded. Finally, the high-precision intelligent adjustable wall formwork system is moved forward by the slide rail 16 to carry out the construction of the next wall.

[0053] S4, Construction of Middle Plate 2: Install disc-lock full-span scaffolding to form the main support of the Middle Plate 2 formwork. Install top supports on the top of the support and lay bamboo plywood. After the formwork is installed, pour concrete and remove the formwork after curing to the specified strength.

[0054] S5. Repeat steps S11 and S12 to complete the construction of the side wall 5, the central partition wall 4, and the top slab 3 of the municipal tunnel 7 in sequence.

[0055] Remove the formwork after curing the top slab concrete to the specified strength.

[0056] Example 2

[0057] As another embodiment, the method of embodiment one yields the following: Figures 1 to 6 As shown, the combined structure system of the open-cut section and the underpass tunnel of the subway includes an overlapping structure system, a retaining structure system, a high-precision intelligent adjustable wall formwork system, and a large-volume concrete sectional pouring system.

[0058] The superimposed structure system includes a base slab 1, a middle slab 2, a top slab 3, a hidden beam 6, and a central partition wall 4 and side walls 5 for the upper and lower structures. The whole structure is a single-box multi-room double-layer frame structure, which is wider at the top and narrower at the bottom. The lower part is the subway tunnel 8, and the upper part is the municipal tunnel 7. The central partition wall 4 and side walls 5 of the upper and lower structures are respectively cast in the middle and on both sides of the base slab 1 and the middle slab 2, dividing the subway tunnel 8 into two compartments on the left and right, and the municipal tunnel 7 into two compartments on the left and right and the central pipeline corridor. The hidden beam 6 is set between the upper central pipeline corridor and the lower subway tunnel central partition wall 4 to improve the overall stress. The steel bars of the hidden beam 6 are set in conjunction with the steel bars of the middle slab 2, and the hidden beam 6 and the middle slab 2 are integrally cast in place.

[0059] The retaining structure system includes an upper foundation pit retaining structure and a lower foundation pit retaining structure. The upper foundation pit retaining structure adopts a hybrid support system of "drilled interlocking piles 17 + reinforced concrete supports 18 + steel pipe supports 20". The drilled interlocking piles 17 are arranged in an alternating manner of plain concrete piles and reinforced concrete piles to form a pile wall. The reinforced concrete supports 18 are connected to the pile wall through capping beams 19 to form the first horizontal support. The steel pipe supports 20 are connected to the pile wall cofferdam through a new type of movable steel support hanging plate to form the second and third horizontal supports. The new type of movable steel support hanging plate includes steel hooks 31, hanging plates 30, stiffening ribs 29, and steel plate base supports 28. This is to ensure close contact between the steel support end and the steel waler of the pile wall, ensuring normal axial force application; the steel hook 31 is welded to the hanging plate 30 through the hole to achieve connection between the new movable steel support hanging plate and the pile wall cofferdam; the bottom of the hanging plate 30 is welded with a steel plate base 28 to ensure that the elevation of both ends of the steel support is consistent; the two ends of the steel plate base 28 are welded with stiffening ribs 29, and the stiffening ribs 29 are also welded to the hanging plate 30; the lower foundation pit retaining structure adopts the support form of "anchor rod 22 + prestressed anchor cable 21 + steel mesh sprayed surface layer"; the anchor rod 22 is fixed on the lower foundation pit excavation slope; the prestressed anchor cable 21 is fixed on the concrete platform 23;

[0060] The high-precision intelligent adjustable wall formwork system includes an L-shaped steel formwork 9, tie rods 10, stiffening plates 11, bolts 12, horizontal adjustment rails 13, a hydraulic device 14, a sliding platform 15, and a slide rail 16. The L-shaped steel formwork 9 is fixed to the hydraulic device 14 by bolts 12. The tie rods 10 are installed on the left and right L-shaped steel formwork 9 of the same side wall formwork to achieve the connection between the two side steel formworks. The stiffening plates 11 are welded to the horizontal plate of the L-shaped steel formwork 9 to improve the overall stability of the formwork. The hydraulic device 14 is installed on the sliding platform 15 to achieve the vertical lifting and lowering of the steel formwork. The sliding platform 15 is equipped with horizontal adjustment rails 13 to achieve the horizontal movement of the hydraulic device 14. The sliding platform 15 is installed on the slide rails 16 to achieve the movement of the wall formwork.

[0061] The large-volume sectional casting system includes the casting of the bottom slab 1, the middle slab 2, the top slab 3, and the middle partition wall 4 and the side wall 5 of the upper and lower structures. Following the principle of "vertical layering and division of construction sections by expansion joints in the plane", the bottom slab 1, the lower structure side wall 5 and the middle partition wall 4, the middle slab 2, the upper structure side wall 5 and the middle partition wall 4, and the top slab 3 are cast in sequence.

[0062] Furthermore, the flat plate positioner 27 is welded to the moving plate of the roll welding machine and pre-connected to each longitudinal bar 24 to fix the relative position of each longitudinal bar 24 on the steel cage.

[0063] Furthermore, the straight threaded sleeve 26 is overlapped between the longitudinal bars 24 of different sections of the steel cage to solve the problem of severe misalignment between the longitudinal bars 24 on the same end face of the two sections of the steel cage and difficulty in achieving qualified connection standards.

[0064] Furthermore, the cavity between the side wall 5 of the subway tunnel 8 and the rock mass is backfilled with cohesive soil to form a stable filling layer and reduce structural damage caused by uneven settlement of the filling material.

[0065] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 1 can be referred to each other, and will not be repeated in this application.

[0066] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

Claims

1. A construction method for a combined open-cut section and underpass tunnel structure system for subways, characterized in that, Includes the following steps: S1. Pile wall construction: The steel cage of the bored interlocking pile is precisely fixed using a flat plate locator, and the longitudinal reinforcement is connected by a straight threaded sleeve connection; bored interlocking piles are drilled around the foundation pit to form a pile wall; S2. Excavate the foundation pit and construct the capping beam and reinforced concrete support at the top of the pile wall; continue to excavate the foundation pit and set two layers of steel pipe support between the pile walls through movable steel support plates to form the upper foundation pit retaining structure; continue to excavate the foundation pit with slope and construct the lower foundation pit retaining structure. The movable steel support hanging plate includes steel hooks, a hanging plate, stiffening ribs, and a steel plate base support. The steel hooks are welded to the upper end of the hanging plate through holes, and the movable steel support hanging plate is hung on the pile wall cofferdam through the steel hooks. The steel plate base support is welded to the bottom of the hanging plate for supporting the end of the steel pipe. Stiffening ribs are welded to both ends of the steel plate base support, and the stiffening ribs are also welded to the hanging plate. The foundation pit below the upper foundation pit retaining structure is excavated by slope excavation, and a concrete platform is provided on the inner side of the pile wall. The lower foundation pit retaining structure includes anchor rods, prestressed anchor cables and steel mesh sprayed surface. The anchor rods are fixed on the excavation slope of the foundation pit where the subway tunnel is located; the prestressed anchor cables are fixed on the concrete platform. S3. Pour the bottom slab at the bottom of the foundation pit, fix the wall formwork of the side walls and central partition walls of the subway tunnel through a high-precision intelligent wall formwork system, and then stabilize it with tie rods; pour concrete in sections and advance the construction in sections through slide rails. The high-precision intelligent adjustable wall formwork system includes an L-shaped steel formwork, tie rods, stiffening plates, bolts, a horizontal adjustment rail, a hydraulic device, a sliding platform, and a slide rail. The L-shaped steel formwork is fixed to the hydraulic device by bolts. The tie rods are installed between the L-shaped steel formworks to connect the two sides. The stiffening plates are welded to the horizontal plate of the L-shaped steel formwork. The hydraulic device is installed on the sliding platform to achieve vertical lifting and lowering of the steel formwork. A horizontal adjustment rail is provided on the sliding platform, and the hydraulic device moves laterally along the horizontal adjustment rail. The sliding platform is installed on the slide rail, and the sliding platform moves longitudinally along the slide rail. S4. Construct intermediate slabs on the top of the side walls and central partition walls of the subway tunnel section, and pre-embed hidden beams; S5. Use the same method as in step S3 to complete the construction of the side walls and central partition walls of the municipal tunnel, and then construct the top slab; When pouring concrete in sections for the side walls and central partition walls of a municipal tunnel, the movable steel support plates and steel pipe supports should be removed accordingly.

2. The construction method of the combined open-cut section and underpass tunnel structure system of the subway as described in claim 1, characterized in that, In step S1: the flat plate positioner is welded to the moving plate of the roll welding machine. When the steel cage of the drilled interlocking pile is welded, the longitudinal bars in the steel cage are welded to the flat plate positioner, and straight threaded sleeves are lapped between the longitudinal bars of different sections of the steel cage.

3. The construction method of the combined open-cut section and underpass tunnel structure system of the subway as described in claim 1, characterized in that, In step S2: the reinforced concrete support is connected to the top of the pile wall through the cap beam to form the first horizontal support; the two layers of steel pipe support are connected to the pile wall cofferdam through movable steel support hanging plates to form the second and third horizontal supports.

4. The construction method of the combined open-cut section and underpass tunnel structure system of the subway as described in claim 1, characterized in that, In step S3: First, check the geological conditions at the bottom of the foundation pit, then carry out the construction of the foundation slab cushion layer, waterproof layer and waterproof protective layer; carry out the bottom slab reinforcement binding and concrete pouring, and after the bottom slab concrete has cured to the specified strength, remove the supporting formwork of the bottom slab.

5. The construction method of the combined open-cut section and underpass tunnel structure system of the subway as described in claim 1, characterized in that, In step S3: the reinforcing bars of the side walls and central partition walls of the subway tunnel are tied. After the tying is completed, the high-precision intelligent adjustable wall formwork system is moved to the construction position. The L-shaped steel formwork is fixed at the construction requirements by adjusting the hydraulic device and the horizontal adjustment rail. Then, tie rods are installed to fix the two L-shaped steel formworks together. After all the formwork is fixed, concrete is poured in sections, with each section being a pouring cycle. After the concrete of the side walls and central partition walls has cured, the formwork is demolded. Finally, the sliding platform is moved forward by the slide rail to carry out the construction of the next section.

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