In-situ protection structure and construction method for pipelines in foundation pits for open-cut subway entrances and exits

Abstract

The present invention discloses an in-situ protection structure and construction method for pipelines in foundation pits of open-cut subway entrances and exits, wherein the pipeline in-situ protection structure comprises support piles, a steel main beam, a steel secondary beam, a grid steel frame and height adjustment bolts; a connecting piece is pre-buried in the support pile, and the support pile is connected to the steel main beam and the grid steel frame through the connecting piece; the steel secondary beam passes through the bottom of the pipe and is placed on the main beam, and the steel main beam is provided with the height adjustment bolt, and the height of the steel secondary beam is adjusted by the height adjustment bolt, so that the steel secondary beam is closely attached to the protected pipeline to form an in-situ protection structure for the pipeline. The present invention avoids pipeline relocation by combining the pipeline in-situ protection structure with the foundation pit retaining structure, so as to effectively shorten the construction period and save the project cost, and at the same time solves the problem of excessive spacing between the retaining piles on both sides of the pipeline, thereby ensuring the safety of the foundation pit and having a strong promotion value.

Description

Technical Field

[0001] The invention belongs to the technical field of underground engineering, and in particular relates to an in-situ protection structure and a construction method for pipelines in a foundation pit for an open-cut subway entrance and exit. Background Art

[0002] As society continues to develop and urban underground space continues to expand, it is inevitable that subway entrance and exit foundation pits will intersect with municipal pipelines. To ensure the safety of the foundation pits and reduce the impact on the pipelines, the traditional approach is to relocate the pipelines and restore them to their original state after the station construction is completed. However, in practice, some pipelines are difficult to relocate due to various factors, so they can only be protected in situ.

[0003] Whether temporary relocation or in-situ protection is adopted, the following problems exist:

[0004] 1) Pipeline relocation will increase the project cost and require multiple coordination and docking, which will also result in a longer construction period.

[0005] 2) The pipeline occupies the location for the construction of retaining piles. At the same time, considering the impact of the construction retaining piles on the pipeline, a safe distance is reserved for construction, which results in the distance between the two retaining piles on both sides of the pipeline being too large, thus affecting the safety of the foundation pit. Summary of the invention

[0006] In order to solve the above technical problems, the invention provides an in-situ protection structure and construction method for pipelines in open-cut subway entrance and exit foundation pits. By combining the pipeline in-situ protection structure with the foundation pit retaining structure, the construction period can be effectively shortened, the project cost can be saved, and the safety of the foundation pit can be ensured.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] In the first aspect, the present invention provides an in-situ protection structure for pipelines in foundation pits of open-cut subway entrances and exits, comprising support piles, steel main beams, steel secondary beams, grating steel frames and height adjustment bolts. Connectors are pre-embedded in the support piles, and the support piles are connected to the steel main beams and grating steel frames through the connecting members; the steel secondary beams pass through the bottom of the protected pipeline and are resting on the steel main beams, and the steel main beams are provided with height adjustment bolts, and the height of the steel secondary beams is adjusted by the height adjustment bolts so that the steel secondary beams are in close contact with the protected pipeline to form an in-situ protection structure for the pipeline.

[0009] Preferably, the supporting piles on the same side of the protected pipeline are reliably connected to the steel main beam through the connecting piece, and a hanger bar is provided between the supporting column and the steel main beam, one end of the hanger bar is welded to the main bar of the supporting pile, and the other end is welded to the steel main beam; the supporting piles on both sides of the protected pipeline are reliably connected to the grid steel frame through the connecting piece.

[0010] Preferably, the pile diameter of the supporting piles is larger than the pile diameter of general retaining piles.

[0011] Preferably, a connecting piece is embedded in the supporting pile in advance, and the connecting piece consists of anchor bars and arc-shaped steel plates. The size of the steel plate is 5 to 10 cm larger than the wing plate width and web height of the steel main beam, so as to ensure that the steel main beam and the connecting piece can be welded in the event of construction errors.

[0012] Preferably, in order to ensure reliable connection between the supporting piles on both sides of the foundation pit and the steel main beam, a hanger bar is added between the supporting column and the steel main beam, one end of the hanger bar is welded to the main reinforcement of the supporting pile, and the other end is welded to the steel main beam.

[0013] Preferably, the length of the steel secondary beam is not less than the sum of the distance between the piles on both sides of the protected pipeline and the pile diameter; one end of the steel secondary beam driven into the soil layer is pointed, making it easier to drive into the soil layer.

[0014] Preferably, the top wing plate of the steel main beam at the intersection of the steel main beam and the steel secondary beam is provided with four holes, the inner walls of the holes are provided with threads, nuts are welded at the bottom of the holes, and four height adjustment bolts are used to adjust the height of the steel secondary beam.

[0015] Preferably, the supporting piles between the two sides of the pipeline are connected to the grid steel frame through the connecting piece, and an advance small guide pipe is set up to ensure the safety of foundation pit excavation and spray mix is ​​carried out between the piles.

[0016] In a second aspect, an embodiment of the present invention further provides a construction method for an in-situ protection structure for a subway entrance and exit foundation pit pipeline using an open-cut method, the method comprising the following steps:

[0017] Step 1: Drive four support piles on both sides of the protected pipeline and foundation pit;

[0018] Step 2: construct the crown beam and the first retaining support, and then excavate the foundation pit to the bottom elevation of the protected pipeline;

[0019] Step 3: excavate the soil layer on one side of the protected pipeline to the bottom elevation of the steel main beam;

[0020] Step 4: Chisel away the concrete at the positions of the two supporting pile main beams and the hanging bars on the excavation side, weld the steel main beam to the connector, weld one end of the hanging bar to the supporting pile main bar, and weld the other end to the steel main beam;

[0021] Step 5: Drive the secondary steel beam horizontally into the top surface of the main steel beam on the excavation side to the designed position;

[0022] Step 6: excavate the soil layer on the other side of the protected pipeline to the bottom elevation of the steel main beam, and construct the steel main beam on this side in the same way as step 4, so that the steel secondary beam is placed on the steel main beam;

[0023] Step 7: According to the reserved construction space and construction error, the height of the steel secondary beam is adjusted through the height adjustment bolts fixed on the steel main beam, so that the steel secondary beam is close to the bottom of the protected pipeline without leaving any space for pipeline deformation;

[0024] Step eight, excavate the soil layer at the location of the construction pipeline in layers, chisel out the concrete at the location of the grid steel frame between the supporting piles on both sides of the protected pipeline, expose the connecting parts, and weld the grid steel frame to the connecting parts; then set up a small advance guide tube and spray mix between the piles, and then continue to excavate downward in layers.

[0025] Preferably, in step three and step six, manual excavation is used when excavating the soil layers on both sides of the protected pipeline to ensure that the soil layer at the bottom of the protected pipeline is not disturbed as much as possible to prevent the protected pipeline from deformation.

[0026] Preferably, in step 4 and step 8, double-sided welding should be adopted when welding the steel main beam, grid steel frame, connecting parts and hanger bars, and the welding quality should be ensured to form reliable connections between them.

[0027] Preferably, in step five: strictly control the construction accuracy when laying the steel secondary beam, and control the elevation deviation within ±10mm.

[0028] Preferably, in step seven: when constructing the main steel beam, the main steel beam can be appropriately moved downward by a certain distance as a whole to ensure that the protected pipeline is not damaged when the secondary steel beam is installed. Before adjusting the height, use a high-pressure water gun to flush away debris at the contact surface between the protected pipeline and the secondary steel beam.

[0029] The present invention has the following beneficial effects:

[0030] The present invention provides an in-situ protection structure and construction method for pipelines in an open-cut subway entrance and exit foundation pit. The present invention can avoid pipeline relocation through the pipeline in-situ protection structure, effectively shorten the construction period, save engineering costs, and has strong promotion value; the pipeline in-situ protection structure is combined with the retaining structure to solve the problem of excessive spacing between the retaining piles on both sides of the pipeline, ensure the safety of the foundation pit, and has strong market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a schematic elevation diagram of a pipeline in-situ protection structure according to an embodiment of the present invention;

[0033] Figure 2 A schematic cross-sectional view of a pipeline in-situ protection structure according to an embodiment of the present invention;

[0034] Figure 3 It is a schematic plan view of a pipeline in-situ protection structure according to an embodiment of the present invention;

[0035] Figure 4 It is a schematic diagram of a node between a steel main beam and a supporting pile according to an embodiment of the present invention;

[0036] Figure 5 A schematic diagram of a grid steel frame and a support pile node according to an embodiment of the present invention;

[0037] Figure 6 Schematic diagram of a height adjustment bolt node according to an embodiment of the present invention.

[0038] Description of reference numerals:

[0039] 1. Support piles; 2. Steel main beam; 3. Steel secondary beam; 4. Grid steel frame; 5. Height adjustment bolts; 6. Crown beam; 7. Protected pipeline; 8. Hanger rod; 9. Connectors; 10. Advance small duct. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] This embodiment provides an in-situ protection structure for pipelines in foundation pits at subway entrances and exits using an open-cut method. Figures 1 to 6 As shown, it includes support piles 1, steel main beams 2, steel secondary beams 3, grid steel frames 4, height adjustment bolts 5, crown beams 6, protected pipelines 7, hangers 8, connectors 9, and small advance guide tubes 10. Connectors 9 are pre-buried in the support piles 1, and the support piles 1 are connected to the steel main beams 2 and grid steel frames 4 through the connectors 9; the steel secondary beams 3 pass through the bottom of the protected pipeline 7 and are placed on the steel main beams 2, and the steel main beams 2 are provided with height adjustment bolts 5, and the height of the steel secondary beams 3 is adjusted by the height adjustment bolts 5, so that the steel secondary beams 3 are closely attached to the protected pipeline 7, forming an in-situ pipeline protection structure.

[0042] The support pile 1 on the same side of the protected pipeline 7 is reliably connected to the steel beam 2 through the connector 9. A hanger bar 8 is added between the support column 1 and the steel beam 2. One end of the hanger bar 8 is welded to the main bar of the support pile 1, and the other end is welded to the steel beam 2; the support piles 1 on both sides of the protected pipeline 7 are reliably connected to the grid steel frame 4 through the connector 9. The pile diameter of the support pile 1 is larger than that of the general section enclosure pile. A connector 9 is buried in the support pile. The connector 9 is composed of anchor bars and arc-shaped steel plates. The size of the steel plate is 5 to 10 cm larger than the wing plate width and web plate height of the steel beam 2, ensuring that the steel beam 2 and the connector 9 can be welded in the case of construction errors. A hanger bar 8 is also provided between the support column 1 and the steel beam 2. One end of the hanger bar 8 is welded to the main bar of the support pile 1, and the other end is welded to the steel beam 2. The length of the steel secondary beam 3 is not less than the sum of the distance between the piles and the pile diameter on both sides of the protected pipeline 7. One end of the steel secondary beam 3 driven into the soil layer is pointed, making it easier to drive into the soil layer. The top wing plate of the steel main beam 2 at the intersection of the steel main beam 2 and the steel secondary beam 3 is punched with four holes, the inner wall of the hole is threaded, and nuts are welded at the bottom of the hole, which are matched with four height adjustment bolts 5 to adjust the height of the steel secondary beam 3. The support piles 1 between the two sides of the pipeline are connected to the grid steel frame 4 through the connecting piece 9. In order to ensure the safety of foundation pit excavation, an advance small guide tube 10 is set and spraying and mixing between piles is carried out.

[0043] In this embodiment, four supporting piles 1 are set on both sides of the protected pipeline 7 and the foundation pit to serve as the entrance and exit foundation pit retaining piles and pipeline supporting piles. The supporting piles 1 need to be pre-buried with connectors 9 in advance. The steel main beam 2 is reliably connected to the supporting piles through the hanger 8 and the connector 9. The steel secondary beam 3 is placed on the steel main beam 2 to support the protected pipeline 7. Four holes (the inner wall of the hole is threaded) are set on the top wing plate of the steel main beam 2 at the intersection of the steel secondary beam 3 and the steel main beam 2, and nuts are welded at the bottom of the holes; the height adjustment bolts 5 adjust the height of the steel secondary beam 3 through the nuts, so that the steel secondary beam 3 is close to the protected pipeline 7, forming a pipeline in-situ protection structure. The grid steel frame 4 and the advanced small guide tube 10 are used as the supporting structure between the supporting piles 1 on both sides of the protected pipeline 7 to ensure the safety of foundation pit excavation.

[0044] Specifically, if Figures 4 to 5 As shown, when making the steel cage, the supporting pile 1 pre-buries the connecting piece 9 according to the measured elevation of the pipeline; a hole is punched on the top wing plate of the steel main beam 2 at the intersection of the steel main beam 2 and the steel secondary beam 3 (the inner wall of the hole is threaded), and a nut is welded at the bottom of the hole.

[0045] Furthermore, the supporting piles 1 on one side of the protected pipeline 7 are connected through the steel main beam 2. Specifically, Figures 1 to 4As shown, after layered excavation to the bottom elevation of the steel main beam 2, the arc-shaped steel plate of the connecting piece 9 is chiseled out, and the end of the steel main beam 2 is welded to the connecting piece 9. At the same time, the main reinforcement is chiseled out at the appropriate position, so that one end of the hanger bar 8 is welded to the main reinforcement of the support pile 1, and the other end is welded to the steel main beam 2.

[0046] Furthermore, the steel secondary beam 3 passes through the bottom of the protected pipeline 7 and is driven horizontally into the soil layer. Figures 1 to 3 As shown, on the first excavation side, a steel secondary beam 3 is horizontally driven close to the top of the steel main beam 2 to the designed position.

[0047] Furthermore, the supporting pile 1 on the other side of the protected pipeline 7 is connected to the steel main beam 2, and the steel secondary beam 3 is placed on the steel main beam 2. Specifically, Figures 1 to 4 As shown, after layered excavation to the bottom elevation of the steel main beam 2, the arc-shaped steel plate of the connecting piece 9 is chiseled out, the steel main beam 2 is placed under the steel secondary beam 3, and the end of the steel main beam 2 is welded to the connecting piece 9. At the same time, the main reinforcement is chiseled out at the appropriate position, so that one end of the hanger rod 8 is welded to the main reinforcement of the support pile 1, and the other end is welded to the steel main beam 2.

[0048] Furthermore, the height of the steel secondary beam 3 is adjusted by the height adjustment bolt 5, so that the steel secondary beam 3 is closely attached to the protected pipeline 7, forming an in-situ pipeline protection structure. Figure 5 As shown, according to the reserved construction space and the construction error, the height adjustment bolt 5 is tightened, and as the height adjustment bolt 5 continues to move upward, the steel secondary beam 3 is lifted up so that it is in close contact with the protected pipeline 7.

[0049] Furthermore, the supporting piles 1 on both sides of the protected pipeline 7 are connected to the grid steel frame 4. Specifically, Figures 1 to 4 , Figure 6 As shown, after the foundation pit is excavated to a certain depth, the arc-shaped steel plate of the connecting piece 9 needs to be chiseled out, the end of the grid steel frame 4 is welded to the connecting piece 9, and at the same time, an advance small guide tube 10 is installed and spray mixing is carried out between the piles.

[0050] This embodiment also provides a construction method for an in-situ protection structure for a subway entrance and exit foundation pit pipeline using an open-cut method, the method comprising the following steps:

[0051] Step 1: four supporting piles 1 are driven on both sides of the protected pipeline 7 and the foundation pit;

[0052] Step 2: construct the crown beam 6 and the first enclosure support, and then excavate the foundation pit to the bottom elevation of the pipeline 7;

[0053] Step 3: excavate the soil layer on one side of the protected pipeline 7 to the bottom elevation of the steel main beam 2;

[0054] Step 4: Chisel away the concrete at the positions of the main beams of the two supporting piles 1 and the hanger bars 8 on the excavation side, weld the steel main beam 2 to the connector 9, weld one end of the hanger bar 8 to the main bar of the supporting pile 1, and weld the other end to the steel main beam 2;

[0055] Step 5: Drive the steel secondary beam 3 horizontally into the top surface of the steel main beam 2 on the excavation side to the designed position;

[0056] Step 6: excavate the soil layer on the other side of the protected pipeline 7 to the bottom elevation of the steel main beam 2, and construct the steel main beam 2 on this side in the same way as step 4, so that the steel secondary beam 3 is placed on the steel main beam 2;

[0057] Step 7: According to the reserved construction space and the construction error, the height of the steel secondary beam 3 is adjusted by the height adjustment bolts 5 fixed on the steel main beam 2, so that the steel secondary beam 3 is close to the bottom of the protected pipeline 7, leaving no space for pipeline deformation;

[0058] Step eight, excavate the soil layer at the location of the protected pipeline 7 in layers, remove the concrete at the location of the grid steel frame 4 between the supporting piles 1 on both sides of the protected pipeline 7, expose the connecting piece 9, weld the grid steel frame 4 and the connecting piece 9; then set up the advance small guide tube 10 and spray mix between the piles, and then continue to excavate downward in layers.

[0059] Furthermore, in step three and step six: manual excavation is used when excavating the soil layers on both sides of the protected pipeline 7 to ensure that the soil layer at the bottom of the protected pipeline 7 is not disturbed as much as possible to prevent the protected pipeline 7 from deformation.

[0060] Furthermore, in step 4 and step 8: double-sided welding should be adopted when welding the steel main beam 2, grid steel frame 4, connecting piece 9 and hanger 8, and the welding quality should be ensured to form a reliable connection between them.

[0061] Furthermore, in step five: when laying the steel secondary beam 3, the construction accuracy is strictly controlled, and the elevation deviation is controlled within ±10 mm.

[0062] Furthermore, in step seven: when constructing the steel main beam 2, it can be appropriately moved down a certain distance as a whole to ensure that the protected pipeline 7 is not damaged when the steel secondary beam 3 is installed, and before adjusting the height, use a high-pressure water gun to flush out debris at the contact surface between the protected pipeline 7 and the steel secondary beam 3.

[0063] It can be seen from the above technical solutions that the embodiment of the present invention provides a pipeline in-situ protection structure and construction method for an open-cut subway entrance and exit foundation pit. By combining the pipeline in-situ protection structure with the foundation pit retaining structure, the pipeline relocation is avoided, the construction period is effectively shortened, and the project cost is saved. At the same time, the problem of excessive spacing between the retaining piles on both sides of the pipeline is solved, thereby ensuring the safety of the foundation pit and having a strong promotion value.

[0064] The above embodiments of the present invention are described in detail through examples, but the contents described are only exemplary embodiments of the embodiments of the present invention and cannot be considered to limit the scope of implementation of the embodiments of the present invention. The protection scope of the embodiments of the present invention is defined by the claims. Anyone who utilizes the technical solutions described in the embodiments of the present invention, or who, inspired by the technical solutions of the embodiments of the present invention, designs similar technical solutions within the essence and protection scope of the embodiments of the present invention to achieve the above technical effects, or who makes equal changes and improvements to the scope of application, shall still fall within the scope of protection covered by the patent of the embodiments of the present invention.

Claims

1. An in-situ protection structure for pipelines in foundation pits at open-cut subway entrances and exits, characterized in that: The invention comprises a support pile (1), a steel main beam (2), a steel secondary beam (3), a grille steel frame (4) and a height adjustment bolt (5); a connecting piece (9) is pre-buried in the support pile (1); the support pile (1) is connected to the steel main beam (2) and the grille steel frame (4) via the connecting piece (9); the steel secondary beam (3) passes through the bottom of the protected pipeline (7) and rests on the steel main beam (2); the steel main beam (2) is provided with the height adjustment bolt (5); the height of the steel secondary beam (3) is adjusted via the height adjustment bolt (5) so that the steel secondary beam (3) is in close contact with the protected pipeline (7); The support pile (1) on the same side of the protected pipeline (7) is connected to the steel main beam (2) via the connecting piece (9); a hanger bar (8) is provided between the support pile (1) and the steel main beam (2); one end of the hanger bar (8) is welded to the main bar of the support pile (1), and the other end is welded to the steel main beam (2); the support piles (1) on both sides of the protected pipeline (7) are connected to the grid steel frame (4) via the connecting piece (9); The pile diameter of the support pile (1) is larger than the pile diameter of a general retaining pile.

2. The in-situ protection structure for pipelines in open-cut subway entrances and exits according to claim 1 is characterized in that: A connecting piece (9) is embedded in the supporting pile (1), the connecting piece (9) being composed of anchor bars and an arc-shaped steel plate, the size of the arc-shaped steel plate being 5 to 10 cm larger than the wing plate width and web plate height of the steel main beam (2).

3. The in-situ protection structure for pipelines in open-cut subway entrances and exits according to claim 1 is characterized in that: The length of the steel secondary beam (3) is not less than the sum of the distance between the piles on both sides of the protected pipeline (7) and the pile diameter; and one end of the steel secondary beam (3) driven into the soil layer is pointed.

4. The in-situ protection structure for pipelines in open-cut subway entrances and exits according to claim 1 is characterized in that: Four holes are punched on the top wing plate of the steel main beam (2) at the intersection of the steel main beam (2) and the steel secondary beam (3), the inner walls of the holes are provided with threads, nuts are welded to the bottoms of the holes, and four height adjustment bolts (5) are matched therewith.

5. The in-situ protection structure for pipelines in open-cut subway entrances and exits according to claim 1 is characterized in that: The supporting piles (1) between the two sides of the pipeline are connected to the grid steel frame (4) via the connecting piece (9), and an advance small guide pipe (10) is installed to ensure the safety of foundation pit excavation and to spray mix between the piles.

6. A construction method for an in-situ protection structure for pipelines in a foundation pit of an open-cut subway entrance and exit as claimed in any one of claims 1 to 5, characterized in that: include: Step 1: four supporting piles (1) are driven on both sides of the protected pipeline (7) and the foundation pit; Step 2: construct the crown beam (6) and the first retaining support, and then excavate the foundation pit to the bottom elevation of the protected pipeline (7); Step 3, excavating the soil layer on one side of the protected pipeline (7) to the bottom elevation of the steel main beam (2); Step 4: Chisel away the concrete at the main beam position of the two supporting piles (1) and the position of the hanger bars (8) on the excavation side, weld the steel main beam (2) and the connecting piece (9), weld one end of the hanger bar (8) to the main bar of the supporting pile (1), and weld the other end to the steel main beam (2); Step 5: horizontally drive the steel secondary beam (3) into the designed position on the top surface of the steel main beam (2) attached to the excavation side; Step 6: excavate the soil layer on the other side of the protected pipeline (7) to the bottom elevation of the steel main beam (2), and construct the steel main beam (2) on this side in the same way as step 4, so that the steel secondary beam (3) is placed on the steel main beam (2); Step 7: adjusting the height of the steel secondary beam (3) by means of the height adjustment bolts (5) fixed on the steel main beam (2) according to the reserved construction space and the construction error, so that the steel secondary beam (3) is closely attached to the bottom of the protected pipeline (7) without leaving any space for pipeline deformation; Step eight, excavate the soil layer at the location of the construction pipeline in layers, remove the concrete at the location of the grid steel frame (4) between the supporting piles (1) on both sides of the protected pipeline (7), expose the connecting piece (9), weld the grid steel frame (4) and the connecting piece (9); then set up the advance small guide tube (10) and spray mix between the piles, and then continue to excavate downward in layers.

7. The construction method for the in-situ protection structure of the pipeline in the open-cut subway entrance and exit foundation pit according to claim 6 is characterized in that: In step 3 and step 6: manual excavation is used when excavating the soil layers on both sides of the protected pipeline (7), so as to ensure that the soil layer at the bottom of the protected pipeline (7) is not disturbed as much as possible, so as to prevent the protected pipeline (7) from deformation.

8. The construction method for the in-situ protection structure of the pipeline in the open-cut subway entrance and exit foundation pit according to claim 6 is characterized in that: In step 4 and step 8, double-sided welding should be adopted when welding the steel main beam (2), the grid steel frame (4), the connecting piece (9) and the hanger bar (8) and the welding quality should be ensured so that a reliable connection is formed between them.

9. The construction method for the in-situ protection structure of the pipeline in the open-cut subway entrance and exit foundation pit according to claim 6 is characterized in that: In step 5: when placing the secondary steel beam (3), the construction accuracy is strictly controlled and the elevation deviation is controlled within ±10mm.

10. The construction method for the in-situ protection structure of the pipeline in the open-cut subway entrance and exit foundation pit according to claim 6, characterized in that: In step seven: when constructing the main steel beam (2), the main steel beam (2) is appropriately moved downward by a certain distance as a whole to ensure that the protected pipeline (7) is not damaged when the secondary steel beam (3) is installed. Before adjusting the height, the contact surface between the protected pipeline (7) and the secondary steel beam (3) is flushed with a high-pressure water gun to remove debris.

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