Construction method of a combined anti-buoyancy structure for open-cut underground railway stations in rock strata

Abstract

This invention discloses a construction method for a combined anti-buoyancy structure of an underground railway station in open-cut rock strata, comprising the following steps: excavating surface soil and constructing surface intercepting ditches; excavating the upper part of the station, constructing slope sprayed concrete support, and installing slope anchors; constructing a slope bottom platform and constructing a platform intercepting ditch on the slope bottom platform; excavating the lower part of the station, constructing a ribbed anchor retaining wall; constructing a foundation pit cushion, laying a waterproof layer, and pouring the second basement level of the station structure; constructing anti-buoyancy toes on the slope bottom platform to form a combined anti-buoyancy structure; laying a waterproof layer to complete the station structure construction. This invention combines the advantages of efficient and safe slope excavation in rock strata, and utilizes a combination of permanent and temporary methods, using a slope platform and anti-buoyancy anchor retaining walls to form a combined anti-buoyancy structure. It features simple construction procedures, high safety, good anti-buoyancy effect, and no abandoned works, while also saving construction time and costs, and has broad prospects for promotion.

Description

Technical Field

[0001] This invention belongs to the field of anti-buoyancy technology for underground structures in rail transit, specifically relating to a construction method for a combined anti-buoyancy structure for open-cut underground stations in rock strata. Background Technology

[0002] Cut-and-cover construction is a common method for urban rail transit stations. When an underground station is located below the groundwater level, it will be subject to the buoyancy of groundwater during both construction and operation. Without anti-buoyancy measures, the deformation and stress on the station structure will be significantly compromised, affecting construction and operational safety. Single anti-buoyancy measures are often relatively limited in their effectiveness for underground stations, insufficient to offset all buoyancy forces. Commonly used anti-buoyancy measures, such as anti-uplift piles, are relatively expensive, have strict site requirements, and overlap with station structure construction, severely impacting the construction period. Cut-and-cover stations in rock formations benefit from relatively favorable geological conditions and often employ the slope protection method. This method involves slope protection and retaining walls to support the foundation pit, resulting in high construction efficiency and good economic benefits.

[0003] Chinese patent CN114482128A discloses a novel combined anti-buoyancy construction method for open-cut railway station structures in water-rich special strata. This patent includes the following steps: Step A: Constructing the main retaining piles, lattice columns, and deeply buried foundation piles for the outer extension section of the first basement level. The main retaining piles are located outside the main structure of the open-cut railway station, followed by the construction of a capping beam; Step B: When excavating the foundation pit to the base, installing anti-buoyancy anchor rods; Step C: Setting anti-buoyancy toes on both sides of the station floor slab and casting them integrally. After bricklaying directly above the anti-buoyancy toes, they are then tightened by a toe beam; Step D: After the station floor slab is cast, removing the bottom layer steel support, and constructing the middle slabs, middle columns, and side walls of each floor from bottom to top. When construction reaches the outer extension section of the first basement level, the pile head reinforcement extends into the outer extension section floor slab for anchoring; Step E: Integrating the station roof slab, and then constructing a capping beam. This method features a combination of multiple anti-buoyancy methods, good anti-buoyancy effect, strong station safety and stability, and savings in manpower and resources later on.

[0004] However, the technical solution of this patent is more focused on anti-buoyancy treatment for special water-rich strata.

[0005] Therefore, it is necessary to study an anti-buoyancy structure that is simpler, safer, and more economical to construct using the slope gradation method for rock strata, and its corresponding construction method. Summary of the Invention

[0006] This invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a construction method for a combined anti-buoyancy structure for open-cut underground railway stations in rock strata.

[0007] The technical solution of this invention is: a construction method for a combined anti-buoyancy structure for open-cut underground railway stations in rock strata, comprising the following steps: A. Excavate surface soil and construct surface intercepting ditches; B. Excavate the earth and rock above the station, construct sprayed concrete slope support, and install slope anchors; C. Construct a platform at the bottom of the slope, and then construct a drainage ditch on the platform. D. Excavate the earth and rock beneath the station and construct a ribbed anchor retaining wall; E. Construct the foundation pit cushion layer, lay the waterproof layer, and pour the second basement level structure of the station; F. Construct anti-buoyancy toes on the platform at the bottom of the slope to form a combined anti-buoyancy structure; G. Lay the waterproof layer and complete the station structure construction.

[0008] Furthermore, step B involves excavating the earth and rock above the station, constructing shotcrete slope support, and installing slope anchors. The specific process is as follows: First, excavate the earth and rock above the station and smooth the slope; Then, immediately spray the first layer of concrete to seal the slope; Next, drill holes in the closed slope, install slope anchors, and inject cement mortar into the anchor holes; Finally, after the cement mortar reaches more than 50% of its design strength, steel mesh is installed, and the second layer of concrete is sprayed to complete the shotcrete support for the slope.

[0009] Furthermore, step C involves constructing a platform at the bottom of the slope, and then constructing a drainage ditch on that platform. The specific process is as follows: First, after completing the earthwork excavation of the upper part of the station, a platform intercepting ditch was constructed at the bottom of the slope supported by sprayed concrete. Then, sprayed concrete was used to seal the platform at the bottom of the slope.

[0010] Furthermore, the slope bottom platform serves as a construction platform for excavating the earth and rock beneath the station in step D, and is also used to construct the anti-buoyancy toe in step F.

[0011] Furthermore, step D involves excavating the earth and rock beneath the station and constructing a ribbed anchor retaining wall. The specific process is as follows: First, using the platform at the bottom of the slope as a construction platform, excavate the earth and rock beneath the station; Then, construct the retaining wall capping beam at the platform at the bottom of the slope; Next, construct a ribbed retaining wall and install retaining wall anchors; Finally, the retaining wall bottom beam is constructed at the bottom of the foundation pit.

[0012] Furthermore, step E involves constructing the foundation pit cushion layer, laying the waterproof layer, and pouring the second basement level structure of the station. The specific process is as follows: First, after the earthwork under the station is excavated to the bottom of the pit, the pit foundation layer is immediately constructed to seal the bottom of the pit; Then, the station base slab was poured on the foundation pit cushion layer; Finally, the side walls of the second basement level and the central columns of the station were poured.

[0013] Furthermore, step F involves constructing anti-buoyancy toes on the platform at the bottom of the slope to form a combined anti-buoyancy structure. The specific process is as follows: First, after the construction of the second basement level of the station was completed, steel reinforcement was tied using the platform at the bottom of the slope. Then, in conjunction with the pre-reserved steel bars on the upper part of the retaining wall cap beam, the anti-buoyancy toe was cast in one piece; Finally, the anti-buoyancy toe and the anti-buoyancy anchor retaining wall form a combined anti-buoyancy structure.

[0014] Furthermore, the anti-buoyancy toe in the combined anti-buoyancy structure resists the gravity of the floating toe by backfilling the soil above, thus resisting the buoyancy of the water; the anti-buoyancy anchor retaining wall in the combined anti-buoyancy structure resists the upward buoyancy of the water by the anchoring force between the retaining wall anchor and the rock stratum.

[0015] Furthermore, the combined anti-buoyancy structure in step F is located in the middle position, and there is no need to excavate earthwork for the combined anti-buoyancy structure. The combined anti-buoyancy structure uses the plate-ribbed anchor retaining wall as the foundation for steel reinforcement, which serves as a permanent anti-buoyancy measure.

[0016] Furthermore, the anti-buoyancy anchor retaining wall includes an upper retaining wall capping beam, a vertically arranged plate-ribbed anchor retaining wall, a lower retaining wall bottom beam, and retaining wall anchors for inclined anchoring.

[0017] The beneficial effects of this invention are as follows: This invention combines the construction process of slope protection in rock strata with the bottom elevation of the platform at the bottom of the slope with the bottom elevation of the anti-buoyancy toe. This allows the platform to serve as both a construction platform for the excavation of the lower earth and rock and a platform for constructing the anti-buoyancy toe later, forming a combined anti-buoyancy structure with the anti-buoyancy anchor retaining wall. Traditional anti-buoyancy toes are set on the station floor slab, which results in a large amount of excavation and backfilling due to the outward expansion of the floor slab structure. The anti-buoyancy toe of this invention is set on the middle slab of the station, effectively utilizing the temporary construction platform for rapid construction of the anti-buoyancy toe without further expanding the station foundation pit and increasing the amount of earthwork excavation. It achieves a great anti-buoyancy effect with a minimal amount of work, while avoiding the large machinery and equipment such as rotary drilling rigs and scaffolding typically used for constructing anti-uplift piles as anti-buoyancy structures. This effectively shortens the construction period, saves construction costs, and ensures construction safety.

[0018] The combined anti-buoyancy structure in this invention is formed by combining anti-buoyancy toes and anti-buoyancy anchor retaining walls. During the excavation of the foundation pit, the anti-buoyancy anchor retaining wall primarily bears the soil and rock pressure, functioning as a typical ribbed retaining wall. After the excavation is completed and the station structure is finished, the anti-buoyancy anchor retaining wall, connected to the anti-buoyancy toes, resists upward buoyancy primarily through the anchoring force between the retaining wall anchors and the rock strata. This invention avoids the limitations of traditional retaining walls, which are only used for temporary support during foundation pit excavation. It can also be used for anti-buoyancy during the later operational phase of the station, achieving a combined temporary and permanent engineering effect and improving the project's economic efficiency.

[0019] This invention combines the advantages of efficient and safe rock stratum slope excavation, and forms a combined anti-buoyancy structure by using a slope platform and anti-buoyancy anchor retaining wall in a permanent and temporary manner. It features simple construction procedures, high safety, good anti-buoyancy effect, and no abandoned project, while also saving construction time and cost, and has broad prospects for promotion. Attached Figure Description

[0020] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a cross-sectional view of the open-cut foundation pit of the station in this invention; Figure 3 This is a schematic diagram showing the elevation of the plate-ribbed anchor retaining wall in this invention. Figure 4 This is a plan view of the plate-ribbed anchor retaining wall in this invention. Figure 5 This is a diagram of node A connecting the anti-buoyancy toe and the plate-ribbed anchor retaining wall in this invention; Figure 6 This is a waterproof diagram of the connection node between the anti-buoyancy toe and the plate-ribbed anchor retaining wall in this invention.

[0021] in: 1. Surface intercepting ditch 2. Slope sprayed concrete support 3. Slope anchor bolts; 4. Platform drainage ditch 5. Slope bottom platform; 6. Retaining wall capping beam 7-ribbed retaining wall; 8-ribbed retaining wall anchor. 9. Retaining wall bottom beam; 10. Foundation pit cushion layer 11 Station floor slab 12 Station central column 13. Side wall of basement level 2 14. Anti-buoyancy toe 15. Side wall of basement level 16. Station roof slab 17 Rib Columns 18 Retaining Wall 19 Anti-buoyancy anchor bolt main reinforcement of retaining wall 20 Waterstop strip 21 Grouting pipe 22 Polyurethane sealant. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments: like Figures 1 to 6 As shown, a construction method for a combined anti-buoyancy structure for an open-cut underground railway station in rock strata includes the following steps: A. Excavate the surface soil and construct surface intercepting ditch 1; B. Excavate the earth and rock above the station, construct the slope sprayed concrete support 2, and install the slope anchor 3; C. Construct the slope bottom platform 5, and construct the platform intercepting ditch 4 on the slope bottom platform 5; D. Excavate the earth and rock beneath the station and construct a ribbed anchor retaining wall 7; E. Construct the foundation pit cushion layer 10, lay the waterproof layer, and pour the second basement level structure of the station; F. Construct anti-buoyancy toes 14 on the slope bottom platform 5 to form a combined anti-buoyancy structure; G. Lay the waterproof layer and complete the station structure construction.

[0023] Step B involves excavating the earth and rock above the station, constructing shotcrete slope support 2, and installing slope anchors 3. The specific process is as follows: First, excavate the earth and rock above the station and smooth the slope; Then, immediately spray the first layer of concrete to seal the slope; Next, drill holes in the closed slope, install slope anchors 3, and inject cement mortar into the anchor holes; Then, after the cement mortar reaches more than 50% of the design strength, steel mesh is installed, and the second layer of concrete is sprayed to complete the slope sprayed concrete support 2.

[0024] Step C involves constructing the slope bottom platform 5 and then constructing the platform intercepting ditch 4 on the slope bottom platform 5. The specific process is as follows: First, after completing the earthwork excavation of the upper part of the station, a platform intercepting ditch 4 is constructed at the bottom of the slope of the shotcrete support 2. Then, sprayed concrete was used to seal the bottom platform 5.

[0025] The slope bottom platform 5 serves as the construction platform for excavating the earth and rock below the station in step D, and at the same time, the slope bottom platform 5 is used to construct the anti-buoyancy toe 14 in step F.

[0026] Step D involves excavating the earth and rock beneath the station and constructing the ribbed anchor retaining wall 7. The specific process is as follows: First, using the slope bottom platform 5 as the construction platform, excavate the earth and stone at the bottom of the station; Then, construct the retaining wall capping beam 6 at point 5 on the slope bottom platform; Next, construct the ribbed anchor retaining wall 7 and install the retaining wall anchors 8; Finally, the retaining wall bottom beam 9 is constructed at the bottom of the foundation pit.

[0027] Step E involves constructing the foundation pit cushion layer 10, laying the waterproof layer, and pouring the second basement level structure of the station. The specific process is as follows: First, after the earthwork under the station is excavated to the bottom of the foundation pit, a foundation pit cushion layer of 10 is immediately constructed to seal the bottom of the foundation pit; Then, the station base slab 11 is poured on the foundation pit cushion 10; Finally, the second basement level structure, including the side wall 13 and the central column 12, was poured.

[0028] Step F involves constructing anti-buoyancy toes 14 on the slope bottom platform 5 to form a combined anti-buoyancy structure. The specific process is as follows: First, after the construction of the second basement level of the station is completed, steel reinforcement is tied using the slope bottom platform 5. Then, in conjunction with the pre-reserved steel bars on the upper part of the retaining wall cap beam 6, the anti-buoyancy toe 14 was cast in one piece; Finally, the anti-buoyancy toe 14 and the anti-buoyancy anchor retaining wall form a combined anti-buoyancy structure.

[0029] The anti-buoyancy toe 14 in the combined anti-buoyancy structure resists the gravity of the floating toe 14 by the backfill soil above, thus resisting the buoyancy of the water; the anti-buoyancy anchor retaining wall in the combined anti-buoyancy structure resists the upward buoyancy of the water by the anchoring force between the retaining wall anchor 8 and the rock stratum.

[0030] The combined anti-buoyancy structure in step F is located in the middle position. There is no need to excavate earthwork for the combined anti-buoyancy structure. The combined anti-buoyancy structure uses the plate-ribbed anchor retaining wall 7 as the foundation for steel reinforcement, which serves as a permanent anti-buoyancy measure.

[0031] The anti-buoyancy anchor retaining wall includes a retaining wall capping beam 6 at the top, a vertically arranged plate-ribbed anchor retaining wall 7, a retaining wall bottom beam 9 at the bottom, and retaining wall anchors 8 for inclined anchoring.

[0032] Specifically, when constructing the retaining wall cap beam 6, the upper part of the retaining wall cap beam 6 is reserved with anti-buoyancy anchor rods and main reinforcement bars of the retaining wall, which are then cast together with the anti-buoyancy toe 14 to form a combined station anti-buoyancy structure.

[0033] Specifically, the plate-ribbed anchor retaining wall 7 includes a retaining wall 18 and a rib column 17. During construction, after the slope is cleared, retaining wall anchors 8 are drilled and installed, the reinforcing bars of retaining wall 18 and rib column 17 are tied, and the plate-ribbed anchor retaining wall 7 is formed by pouring concrete.

[0034] Specifically, in step A, surface soil is excavated and surface interception ditch 1 is constructed to prevent surface water from flowing into the foundation pit after large-scale excavation.

[0035] Specifically, step G involves laying the waterproof layer to complete the station structure construction. The specific process is as follows: After the construction of the combined anti-buoyancy structure is completed, a waterproof layer is laid, and the station's basement side wall 15 and station roof slab 16 are poured from bottom to top to complete the station structure construction.

[0036] Specifically, in step C, in conjunction with the construction technology of slope excavation in rock strata, the bottom elevation of the slope bottom platform 5 is consistent with the bottom elevation of the anti-buoyancy toe 14, so as to ensure that the slope bottom platform 5 can be used as a construction platform for the excavation of the lower earth and rock, and can also be used to construct the anti-buoyancy toe 14 in the later stage.

[0037] Specifically, in step C, the anti-buoyancy toe 14 resists the buoyancy of water by the self-weight of the backfill soil above, thereby achieving the anti-buoyancy effect. The anti-buoyancy toe 14 can be quickly constructed through the slope bottom platform 5, without further excavation of the station foundation pit or increase of earthwork excavation, thus achieving a great anti-buoyancy effect with a very small amount of engineering work, and has excellent economic benefits.

[0038] Specifically, in step D, the anti-buoyancy anchor retaining wall consists of a retaining wall cap beam 6, a plate-ribbed anchor retaining wall 7, retaining wall anchors 8, and a retaining wall bottom beam 9. The upper part of the retaining wall cap beam 6 is reserved with the main reinforcement 19 of the anti-buoyancy anchor retaining wall. The reserved length of the reinforcement must be no less than 35d. Later, it is cast integrally with the anti-buoyancy toe 14 to form a combined station anti-buoyancy structure. As a permanent structure, the durability of the combined anti-buoyancy structure must be consistent with the station structure.

[0039] Specifically, in step F, after the construction of the second basement level of the station is completed, the anti-buoyancy toe steel cage is tied using the slope bottom platform 5, and the anti-buoyancy toe 14 is cast in one piece in conjunction with the pre-reserved steel bars on the upper part of the retaining wall cap beam 6, forming a combined anti-buoyancy structure.

[0040] Specifically, the anti-buoyancy toe 14 is located in the middle, the upper part of the anti-buoyancy toe 14 is the first negative side wall 15, and the lower part of the anti-buoyancy toe 14 is the second negative side wall.

[0041] Specifically, the anti-buoyancy toe 14 does not cover the platform drainage ditch 4 laterally.

[0042] Specifically, the waterproofing of the connection node between the anti-buoyancy toe 14 and the anti-buoyancy anchor retaining wall includes the following process: First, a waterproof layer is laid on the water-facing side of the station's first basement side wall 15, second basement side wall 13, and anti-buoyancy toe 14. Then, two waterstop strips 20 and grouting pipes 21 are installed at the joint between the anti-buoyancy toe 14 and the retaining wall crown beam 6 for grouting. Polyurethane sealant 22 is installed on the inner and outer sides of the crown beam to meet the waterproof performance requirements of the combined anti-buoyancy structure.

[0043] This invention combines the construction process of slope protection in rock strata with the bottom elevation of the platform at the bottom of the slope with the bottom elevation of the anti-buoyancy toe. This allows the platform to serve as both a construction platform for the excavation of the lower earth and rock and a platform for constructing the anti-buoyancy toe later, forming a combined anti-buoyancy structure with the anti-buoyancy anchor retaining wall. Traditional anti-buoyancy toes are set on the station floor slab, which results in a large amount of excavation and backfilling due to the outward expansion of the floor slab structure. The anti-buoyancy toe of this invention is set on the middle slab of the station, effectively utilizing the temporary construction platform for rapid construction of the anti-buoyancy toe without further expanding the station foundation pit and increasing the amount of earthwork excavation. It achieves a great anti-buoyancy effect with a minimal amount of work, while avoiding the large machinery and equipment such as rotary drilling rigs and scaffolding typically used for constructing anti-uplift piles as anti-buoyancy structures. This effectively shortens the construction period, saves construction costs, and ensures construction safety.

[0044] The combined anti-buoyancy structure in this invention is formed by combining anti-buoyancy toes and anti-buoyancy anchor retaining walls. During the excavation of the foundation pit, the anti-buoyancy anchor retaining wall primarily bears the soil and rock pressure, functioning as a typical ribbed retaining wall. After the excavation is completed and the station structure is finished, the anti-buoyancy anchor retaining wall, connected to the anti-buoyancy toes, resists upward buoyancy primarily through the anchoring force between the retaining wall anchors and the rock strata. This invention avoids the limitations of traditional retaining walls, which are only used for temporary support during foundation pit excavation. It can also be used for anti-buoyancy during the later operational phase of the station, achieving a combined temporary and permanent engineering effect and improving the project's economic efficiency.

[0045] This invention combines the advantages of efficient and safe rock stratum slope excavation, and forms a combined anti-buoyancy structure by using a slope platform and anti-buoyancy anchor retaining wall in a permanent and temporary manner. It features simple construction procedures, high safety, good anti-buoyancy effect, and no abandoned project, while also saving construction time and cost, and has broad prospects for promotion.

Claims

1. A construction method for a combined anti-buoyancy structure for open-cut underground railway stations in rock strata, characterized in that: Includes the following steps: A. Excavate the surface soil and construct the surface intercepting ditch (1). B. Excavate the earth and rock above the station, construct slope sprayed concrete support (2), and install slope anchors (3). C. Construct a slope bottom platform (5) and construct a platform intercepting ditch (4) on the slope bottom platform (5); D. Excavate the earth and stone under the station and construct a ribbed anchor retaining wall (7). E. Construct the foundation pit cushion layer (10), lay the waterproof layer, and pour the station's second basement level structure; F. Construct anti-buoyancy toes (14) on the slope bottom platform (5) to form a combined anti-buoyancy structure; G. Lay the waterproof layer and complete the station structure construction; The combined anti-buoyancy structure in step F is placed in the middle position. There is no need to excavate earthwork for the combined anti-buoyancy structure. The combined anti-buoyancy structure uses the plate-ribbed anchor retaining wall (7) as the foundation for steel reinforcement and as a permanent anti-buoyancy structure. The anti-buoyancy anchor retaining wall includes a retaining wall capping beam (6) at the top, a vertically arranged plate-ribbed anchor retaining wall (7), a retaining wall bottom beam (9) at the bottom, and retaining wall anchors (8) for inclined anchoring. In step F, after the construction of the second basement level of the station is completed, the anti-buoyancy toe steel cage is tied using the slope bottom platform (5), and the anti-buoyancy toe (14) is cast in one piece in conjunction with the pre-reserved steel bars on the upper part of the retaining wall cap beam (6). The anti-buoyancy toe (14) and the anti-buoyancy anchor retaining wall form a combined anti-buoyancy structure. The anti-buoyancy toe (14) is located in the middle, and the anti-buoyancy toe (14) above it is the first-level negative side wall (15), and the anti-buoyancy toe (14) below it is the second-level negative side wall; The anti-buoyancy toe (14) does not cover the platform drainage ditch (4) laterally. The waterproofing of the connection node between the anti-buoyancy toe (14) and the anti-buoyancy anchor retaining wall includes the following process: First, a waterproof layer is laid on the water-facing side of the first basement level side wall (15), the second basement level side wall (13), and the anti-buoyancy toe (14) of the station; Then, two waterstop strips (20) and grouting pipes (21) are installed at the joint between the anti-buoyancy toe (14) and the retaining wall crown beam (6) for grouting. Polyurethane sealant (22) is installed on the inner and outer sides of the crown beam to meet the waterproof performance requirements of the combined anti-buoyancy structure. The anti-buoyancy toe (14) in the combined anti-buoyancy structure resists the gravity of the floating toe (14) by the backfill soil above, and resists the buoyancy of water; the anti-buoyancy anchor retaining wall in the combined anti-buoyancy structure resists the upward buoyancy of water by the anchoring force between the retaining wall anchor (8) and the rock layer.

2. The construction method of a combined anti-buoyancy structure for open-cut underground railway stations in rock strata according to claim 1, characterized in that: Step B involves excavating the earth and rock above the station, constructing shotcrete slope support (2), and installing slope anchors (3). The specific process is as follows: First, excavate the earth and rock above the station and smooth the slope; Then, immediately spray the first layer of concrete to seal the slope; Then, drill holes in the closed slope, install slope anchors (3), and inject cement mortar into the anchor holes; Finally, after the cement mortar strength reaches more than 50% of the design strength, steel mesh is hung and the second layer of concrete is sprayed to complete the slope sprayed concrete support (2).

3. The construction method of a combined anti-buoyancy structure for open-cut underground railway stations in rock strata according to claim 1, characterized in that: Step C involves constructing a slope bottom platform (5) and then constructing a platform intercepting ditch (4) on the slope bottom platform (5). The specific process is as follows: First, after the earthwork excavation of the upper part of the station is completed, a platform intercepting ditch (4) is constructed at the bottom of the slope of the sprayed concrete support (2). Then, spray concrete is used to seal the platform at the bottom of the slope (5).

4. The construction method of a combined anti-buoyancy structure for open-cut underground railway stations in rock strata according to claim 1, characterized in that: Step D involves excavating the earth and rock beneath the station and constructing a ribbed anchor retaining wall (7). The specific process is as follows: First, the earthwork under the station was excavated using the slope bottom platform (5) as the construction platform. Then, a retaining wall capping beam (6) is constructed at the bottom platform (5). Next, construct a ribbed anchor retaining wall (7) and install retaining wall anchors (8). Finally, a retaining wall bottom beam (9) is constructed at the bottom of the foundation pit.

5. The construction method of a combined anti-buoyancy structure for open-cut underground railway stations in rock strata according to claim 1, characterized in that: Step E involves constructing the foundation pit cushion layer (10), laying the waterproof layer, and pouring the second basement level structure of the station. The specific process is as follows: First, after the earthwork under the station is excavated to the bottom of the pit, the pit cushion layer (10) is immediately constructed to seal the bottom of the pit; Then, the station base slab (11) is poured on the foundation pit cushion layer (10). Finally, the side walls (13) of the second basement level and the central column (12) of the station were poured.

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