A primary support system and construction method for the interface of an auxiliary cross passage of a concealed subway station

Abstract

The present invention relates to a primary support system and construction method for the interface of an auxiliary transverse passage at a dark-excavated subway station. The primary support system comprises a cantilevered station tunnel primary support, an auxiliary transverse passage primary support, and a primary support system for an additional portal on the inner side of the auxiliary transverse passage interface. The present invention can complete force conversion at the additional portal before the auxiliary transverse passage interface is opened. This significantly improves the machining accuracy requirements and difficulty of the steel frame, allowing the additional portal to complete the truncation and excavation of the side wall steel frame of the station tunnel arch under effective support and protection, thus resolving the issue of exposed suspended surfaces of the station tunnel arch caused by opening the tunnel and reducing construction risks.

Description

Technical Field

[0001] The present invention relates to an interface primary support system, in particular to an interface primary support system for an auxiliary transverse passage of a concealed excavated subway station, and also to a construction method thereof, belonging to the field of subway tunnel design and construction. Background Art

[0002] In existing rock formations, underground excavation is often used to construct subway stations. Due to the characteristics of underground excavation stations with single-arch, large-span and large-section tunnels, auxiliary passages often need to open holes in the curved side walls of the station arch to form interfaces. When opening holes, the station arch above the portal is suspended and easily collapses. As the span and height of the auxiliary portal increase, the suspended surface of the opening makes it impossible for the load of the upper station arch to be transmitted downward, the station arch is biased, and the construction risk also increases exponentially.

[0003] The current common practice is to cut off the main steel frame within the portal range, then carry out a one-time blasting excavation to the outer contour of the main side wall and immediately erect a three-dimensional arch steel frame. The size parameters of each three-dimensional arch steel frame are different. In order to ensure the limit, the steel frame processing requires extremely high processing precision. Therefore, the construction quality of the three-dimensional steel frame at the interface cannot be guaranteed. Moreover, even if the steel frame is immediately erected on site and the initial support is sprayed to seal it, the problem of temporary exposure of the suspended surface cannot be eliminated. The portal interface construction is still a "first hole opening and then support" working condition, which is extremely risky. If in poor strata such as weak surrounding rock and broken zones, the station tunnel and ground buildings will be directly threatened during the exposure of the suspended surface. Once the arch collapses, the consequences will be disastrous.

[0004] How to avoid the "opening the hole first and then supporting" arch hanging working condition caused by opening the hole in the side wall of the arch and the complex three-dimensional space steel frame production is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention proposes a primary support system and construction method for the interface of the auxiliary transverse passage of a dark-cut subway station. It is a simple and convenient "support first, then drill a hole" dark-cut subway station auxiliary transverse passage interface construction method and primary support system. It is not only suitable for the auxiliary and construction passages of dark-cut subway stations, but also suitable for the opening of holes on the side walls of large-span and large-section tunnel arches to connect entrances and exits, wind shelter group passages, subway section transverse passages, and railway and highway tunnels and other related design fields.

[0006] The technical solution adopted in the present invention is:

[0007] A primary support system for the interface of an auxiliary transverse passage of a dark-excavated subway station, comprising a primary support system for a cantilevered station tunnel, a primary support system for an auxiliary transverse passage, and a primary support system for an additional portal on the inner side of the interface of the auxiliary transverse passage;

[0008] The additional portal primary support system includes the additional portal steel frame, the vertical support steel frame between the additional portal steel frame and the primary support of the cantilevered station tunnel, the advanced support pipe shed and the cantilevered primary support shell anchor rod;

[0009] The shell expansion anchors for the primary support of the cantilever slab are set at the junction of the primary support of the cantilever slab station tunnel and the primary support of the auxiliary cross passage. The driving direction of the cantilever slab primary support shell expansion anchors is perpendicular to the rock surface, and the driving spacing matches the spacing of the vertical support steel frames.

[0010] The additional portal primary support system is connected to the primary support of the cantilevered station tunnel through a vertical support steel frame;

[0011] The construction method includes the following steps:

[0012] Step (1): Excavation of the variable section of the station tunnel at the interface of the auxiliary cross passage:

[0013] The station tunnel is excavated in the existing manner. When the primary support excavation range of the cantilevered station tunnel is extended from the primary support outline steel frame of the standard section of the station tunnel to the outer outline of the additional portal ≥1.5m, the primary support of the cantilevered station tunnel will be extended based on the span of the additional portal at the interface of the auxiliary cross passage being higher than the primary support straightening point of the cantilevered station tunnel. The arch curve of the station tunnel on the side of the additional portal will be adjusted to a primary support vertical wall. The excavation width will be extended to ensure that the primary support system of the additional portal does not intrude into the subsequent secondary lining of the station tunnel. The cantilevered station tunnel primary support shell expansion anchor bolts will be driven at the junction of the primary support and the primary support vertical wall.

[0014] Step (2): construct an additional portal on the inner side of the auxiliary cross channel interface and install advance support:

[0015] After the excavation of the cantilevered station tunnel at the interface portal section is completed and the primary support of the cantilevered station tunnel is installed, multiple additional portal steel frames are erected on the inner side of the primary support vertical wall and below the primary support of the cantilevered station tunnel. Vertical support steel frames are erected above the additional portal steel frames, and an advance support pipe shed is installed, followed by spraying concrete to complete the construction of the additional portal.

[0016] Step (3): Apply initial support:

[0017] After the primary support system of the additional portal in step (2) reaches the designed strength, the primary support vertical wall of the station tunnel is cut off along the outer contour of the additional portal and the auxiliary cross passage is excavated in steps to the deformation joint. The steel frame of the auxiliary cross passage is erected in time and the primary support of the auxiliary cross passage is carried out. Subsequently, the excavation and support of the lower section of the auxiliary cross passage interface are carried out step by step.

[0018] Furthermore, the length of the advance support pipe shed located above the arch of the station tunnel covers the deformation joint of the auxiliary cross passage interface and is not less than 6m.

[0019] Furthermore, the area below the primary support of the cantilevered station tunnel is the primary support expansion range of the cantilevered station tunnel. After the primary support, primary support straight wall and additional portal of the cantilevered station tunnel in the primary support expansion range are completed, the secondary lining of the station tunnel is closely attached to the inner side thereof.

[0020] Furthermore, in step (1), the station tunnel is excavated in the existing manner. When the primary support of the cantilevered slab station tunnel is expanded from the primary support outline steel frame of the standard section of the station tunnel to the outer outline of the additional portal ≥1.5m, the primary support of the cantilevered slab station tunnel is expanded according to the span of the additional portal being higher than the primary support straightening point of the cantilevered slab station tunnel, and the arc line of the arch of the station tunnel on one side of the additional portal is adjusted to a primary support straight wall; the additional portal invades the subsequent secondary lining of the station tunnel, and after the subsequent auxiliary cross passage interface is successfully constructed, the additional portal is broken and the secondary lining of the main structure of the station tunnel is constructed.

[0021] Furthermore, in step (1), each steel frame has ≥2 expansion anchor rods.

[0022] Furthermore, in step (1), if the surrounding rock is very poor, the primary support of the cantilevered station tunnel is not constructed, and the cantilevered station tunnel primary support is straightened at the point where the primary support is taken, and is excavated outward in an arc shape along the original primary support contour of the station tunnel to ensure that the arch of the station tunnel is stressed and to control settlement.

[0023] Furthermore, the additional portal steel frames are densely arranged or connected as a whole by welding with longitudinal reinforcements.

[0024] Furthermore, the advanced support pipe rack adopts a pipe rack with a diameter of φ76~108, a wall thickness of 8mm, and a length of not less than 6m, supplemented by a small guide tube with a diameter of φ42, a wall thickness of 3.5mm, and a length of not less than 3.5m.

[0025] Furthermore, the additional portal steel frame, the primary supporting straight wall steel frame and the vertical supporting steel frame are grid steel frames made by welding steel bars or steel arch frames made by I-beams.

[0026] The initial support of the cantilevered station tunnel should be extended in advance according to the height of the interface channel, and the top arch of the station tunnel should be straightened. At the same time, it should be appropriately expanded according to the outer contour of the standard section of the station tunnel to provide operating space for the "support first and then open the hole" method when the subsequent interface channel is broken.

[0027] There are multiple additional portal arch steel frames along the outer contour of the portal at the interface straight wall. The interface straight wall steel frames are connected to the primary support steel frames of the cantilevered station tunnel through vertical supporting steel frames.

[0028] Small guide tubes, pipe sheds and other advanced support measures are installed above the arch of the interface straight wall steel frame. The length of the pipe shed should be greater than or equal to the length of the deformation joint from the steel frame to the interface channel and not less than 6m.

[0029] The interface straight wall steel frame is longitudinally provided with longitudinal connecting ribs, and the longitudinal ribs and the interface straight wall steel frame are arranged in a plum blossom shape. The interface straight wall steel frame can also be closely welded.

[0030] Shell expansion anchor rods are set at the feet of the primary support of the cantilevered station tunnel, and the shell expansion anchor rods are firmly welded to the primary support steel frame and steel mesh of the cantilevered station tunnel; the primary support steel frame of the cantilevered station tunnel is provided with longitudinal connecting ribs, and the longitudinal ribs are welded to the station tunnel steel frame in a plum blossom shape. The length of the shell expansion anchor rods should be more than 1.5 times that of the anchor rods of the station tunnel system; the additional portal steel frame is connected to the primary support of the cantilevered station tunnel through a vertical support steel frame, and the vertical support steel frame is also provided with longitudinal connecting ribs in a plum blossom shape.

[0031] In step (1), the station tunnel is excavated normally to a point ≥1.5m outside the outer contour of the interface portal, and the cross section is expanded. The cross section top arch is expanded by cantilevering the plate according to the span height of the interface portal and the straightening point. The arc line of the station arch on the portal side is adjusted to a cantilevered plate arch and a straight wall. Locking foot anchor rods are installed at the intersection of the cantilevered plate arch and the straight wall. There should be ≥2 locking foot anchor rods for each steel frame.

[0032] In step (2), after the cross-section excavation of the station tunnel expansion of the interface portal section is completed and concrete is sprayed, multiple additional portal steel frames are erected below the primary support of the cantilever plate on the inner side of the portal vertical wall. The steel frames are closely arranged or connected by longitudinal reinforcement welding. Vertical support steel frames are erected above the additional portal steel frames and advance support such as pipe sheds are installed and concrete is sprayed, that is, "pre-support".

[0033] In step (3), after the initial support of the tunnel portal in step (2) reaches the design strength, the tunnel portal is broken, the initial support vertical wall steel frame of the station tunnel is cut off, and the auxiliary passage is excavated in steps to the deformation joint, and the auxiliary passage steel frame and initial support are erected in time, that is, "later opening of the tunnel".

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] (1) The "support first, then drill" construction method provided by the present invention can complete the force conversion at the tunnel portal before the interface channel is drilled, and at the same time greatly improve the steel frame processing accuracy and processing difficulty, so that the interface tunnel portal can complete the cut-off and demolition of the station arch side wall steel frame under the protection of effective support, solve the problem of exposure of the station arch suspended surface caused by drilling, and reduce construction risks.

[0036] (2) The additional portal constructed on the inner side of the interface breaking point of the present invention can effectively support the station tunnel arch above, bear the suspended load of the station tunnel arch caused by the portal breaking, and control the settlement of the station tunnel arch top; the cantilevered station tunnel primary support lower straight wall converts the three-dimensional steel frame manufacturing problem of the common hole opening method into a two-dimensional steel frame problem, which greatly reduces the difficulty of steel frame processing and realizes the ideal working condition of partial excavation of rock mass during hole breaking, support of passage as it is excavated, and primary support steel frame following the closure step by step. It has strong operability and rapid timeliness, significantly reduces the operational risk of hole opening in the station tunnel arch wall, and effectively shortens the construction period. It has high social, economic and engineering benefits and has extensive practical value in the fields of subway, large railway, highway, underwater tunnel, etc.

[0037] (3) The present invention adopts a partial top arch flat plate cantilever at the interface, and sets an additional portal below the cantilever plate. That is, multiple portal steel frames are connected to the main top arch steel frame through the vertical support steel frame above them, and then concrete is sprayed to achieve force conversion at the interface, transferring the suspended surface load caused by the opening to the structures on both sides of the interface portal. After the force system conversion is completed, under the protection of the additional portal of the multiple steel frames, the main arch wall interface is broken, and the auxiliary channel and construction cross channel are smoothly excavated. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic cross-sectional view of the primary branch system of the first embodiment of the present invention;

[0039] Figure 2 for Figure 1 AA cross-sectional structural diagram;

[0040] Figure 3 for Figure 1 BB cross-sectional structure diagram;

[0041] Figure 4 is a cross-sectional schematic diagram of a primary branch system according to a second embodiment of the present invention;

[0042] In the figure, 1-primary support of cantilevered station tunnel, 2-primary support of auxiliary cross passage, 3-additional portal steel frame, 4-primary support vertical wall, 5-secondary lining of station tunnel, 6-advance support pipe shed, 7-primary support shell expansion anchor of cantilevered station tunnel, 8-straightening point of primary support of cantilevered station tunnel, 9-expansion range of primary support of cantilevered station tunnel, 10-vertical support steel frame, 11-primary support outline of standard section of station tunnel. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] Unless otherwise defined, technical or scientific terms used in the embodiments of this application should have the same ordinary meaning as those of ordinary skill in the art to which the invention pertains. The terms "first," "second," and similar terms used in the embodiments of the present invention do not denote any order, quantity, or importance, but are simply used to distinguish between different components. "Include" or "comprising" and similar terms mean that the element or object preceding the term includes the elements or objects listed after the term, and their equivalents, without excluding other elements or objects. "Installed," "connected," and "connected" should be interpreted broadly, for example, to mean fixed, removable, or integral; directly, indirectly through an intermediary, or internally connected between two components. "Up," "down," "left," "right," "horizontally," and "vertically" are used only with respect to the orientation of components in the drawings. These directional terms are relative concepts and are used for description and clarification purposes. They may vary depending on the orientation of the components in the drawings. Example 1

[0045] This embodiment further illustrates the present invention in combination with the Qingdao Line 4 underground excavation station construction method, the on-site implementation method of the tunnel portal interface and the patent drawings.

[0046] like Figure 1 As shown, the primary support system of the interface of the auxiliary transverse passage of the underground subway station in this embodiment includes the primary support 1 of the cantilevered station tunnel, the primary support 2 of the auxiliary transverse passage and the primary support system of the additional portal on the inner side of the interface.

[0047] The additional portal primary support system includes the additional portal steel frame 3 and primary support sprayed concrete, the vertical support steel frame 10 between the additional portal and the cantilever plate primary support, the advanced support pipe shed 6, and the cantilever plate primary support shell anchor rod 7.

[0048] The station tunnel should select an appropriate cantilevered station tunnel primary support straightening point 8 based on the span and height of the auxiliary cross passage primary support 2, and install cantilevered primary support expansion shell anchors 7 at the intersection to serve as a settlement safety reserve when the subsequent hole is broken to cut off the station tunnel primary support vertical wall 4 steel frame. The installation direction of the cantilevered primary support expansion shell anchors 7 should be perpendicular to the rock surface, and the installation spacing should match the steel frame spacing. Below the station tunnel interface vertical wall, i.e., on the inside of the channel interface, an additional portal steel frame 3 connected by multiple steel frames is installed. The additional portal steel frame 3 is connected to the cantilevered station tunnel primary support 1 through a vertical support steel frame 10. Its arch is equipped with an advance support pipe shed 6 such as a pipe shed and a small guide tube. The length of the advance support pipe shed 6 should cover the auxiliary interface deformation joint and be no less than 6m.

[0049] like Figure 2 As shown, the longitudinal section of the station of the primary support system of the auxiliary transverse passage interface of the underground subway station in this embodiment includes the cantilevered station tunnel primary support 1 at the auxiliary portal and its standard section primary support of the station tunnel, the auxiliary transverse passage primary support 2 below the station primary support, the advanced support pipe shed 6 and the cantilevered primary support shell anchor rod 7 arranged above the auxiliary primary support arch.

[0050] like Figure 3 As shown, the longitudinal section of the auxiliary cross passage interface of the primary support system of the auxiliary cross passage interface of the underground subway station in this embodiment includes the cantilevered station tunnel primary support 1 at the auxiliary portal, the auxiliary cross passage primary support 2 below the cantilevered station tunnel primary support 1, the additional portal steel frame 3 set at the same position, and the vertical support steel frame 10 connected to the station cantilevered primary support above the additional portal steel frame 3.

[0051] The construction method of the primary support system of this embodiment includes the following steps:

[0052] Step (1): Excavation of variable section of station tunnel at the interface

[0053] The station tunnel is excavated in the existing way, e.g. Figure 2 As shown, assuming the primary support excavation range for a cantilevered station tunnel extends ≥1.5m beyond the outer contour of the interface portal from the steel frame of the standard section primary support profile 11, excavation of the cantilevered station tunnel primary support 1 begins based on the interface portal span being higher than the cantilevered station tunnel primary support straightening point 8. The arch of the station arch on the portal side is adjusted to form the station tunnel primary support vertical wall 4. The excavation width should ensure that the additional portal steel frame 3 does not intrude upon the subsequent station tunnel secondary lining structure 5. Cantilevered station tunnel primary support shell expansion anchors 7 are installed at the intersection of the cantilevered station tunnel primary support 1 and the primary support vertical wall 4. At least two shell expansion anchors should be installed per steel frame.

[0054] Step (2): construct an additional portal on the inner side of the auxiliary interface and set up advance support (i.e. "pre-support")

[0055] After the primary support of the station tunnel at the interface portal section is completed, multiple additional portal steel frames 3 are erected inside the station tunnel primary support vertical wall 4 and below the cantilevered station tunnel primary support 1. The steel frames are closely spaced or welded together using longitudinal reinforcement to form a single piece. A vertical support steel frame 10 is erected above the additional portal steel frames 3, and pre-support such as a pipe shed is installed. After spraying concrete, the additional portal steel frames 3 are completed. Pre-support can be achieved using a pipe shed with a diameter of 76-108 mm, a wall thickness of 8 mm, and a length of at least 6 m, supplemented by a small pipe shed with a wall thickness of 42 mm, a wall thickness of 3.5 mm, and a length of at least 3.5 m.

[0056] Step (3): Remove the initial support of the station tunnel vertical wall at the interface, cut off the steel frame, excavate the interface arch using the step method, and promptly erect the auxiliary cross channel steel frame to perform initial support (i.e., "later opening").

[0057] After the primary support system of the additional portal in step (2) reaches the designed strength, the steel frame of the primary support vertical wall 4 of the station tunnel is cut off along the outer contour of the additional portal and the auxiliary cross passage is excavated in steps to the deformation joint. The steel frame of the auxiliary cross passage is erected in time and the primary support 2 of the auxiliary cross passage is constructed. Subsequently, the excavation and support of the lower section of the auxiliary cross passage interface are carried out step by step. Example 2

[0058] like Figure 4 As shown, the construction method of the primary support system of this embodiment is different from that of embodiment 1 only in the stage of excavation of the station tunnel cross-section at the interface of step (1): the station tunnel is excavated in the existing manner, such as Figure 2 As shown, assuming that the primary support excavation range of the cantilevered station tunnel is ≥1.5m outside the outer contour of the primary support 11 steel frame of the standard section of the station tunnel to the outer contour of the interface portal, the primary support 1 contour of the cantilevered station tunnel is expanded according to the interface portal span being higher than the primary support straightening point 8 of the cantilevered station tunnel. The arc line of the station arch on one side of the portal is adjusted to the primary support straight wall 4 of the station tunnel. The additional portal can invade the range of the subsequent station tunnel secondary lining 5. After the subsequent auxiliary cross passage interface is successfully constructed, the additional portal will be broken and the secondary lining of the main structure of the station tunnel will be constructed. This implementation method is suitable for areas with poor surrounding rock and geology. The cantilevered primary support can be tilted as much as possible to fit the original station tunnel arch contour, reducing the risk of station tunnel excavation. Example 3

[0059] In the construction method of the primary support system of this embodiment, in step (1), if the surrounding rock is very poor, the primary support 1 outline of the cantilevered station tunnel is not constructed, and the cantilevered station tunnel primary support straightening point 8 is expanded outward along the original primary support outline of the station tunnel to ensure that the tunnel arch is stressed and the settlement is controlled. The rest is the same as in embodiment 1 or 2.

[0060] The content of the present invention is not limited to the embodiments listed. Any equivalent and similar changes made to the technical solution of the present invention by ordinary technicians in this field after reading the description of the present invention are covered by the protection scope of the claims of the present invention.

Claims

1. A primary support system for the interface of an auxiliary transverse passage in a submerged subway station, characterized by: It includes a primary support system for a cantilevered station tunnel (1), a primary support system for an auxiliary transverse passage (2), and an additional portal primary support system on the inner side of the auxiliary transverse passage interface; The additional portal primary support system includes an additional portal steel frame (3), a vertical support steel frame (10) between the additional portal steel frame (3) and the cantilever type station tunnel primary support (1), an advanced support pipe shed (6), and a cantilever primary support shell anchor rod (7); The cantilever plate primary support shell expansion anchor rod (7) is set at the junction of the cantilever plate type station tunnel primary support (1) and the auxiliary cross passage primary support (2), and the cantilever plate primary support shell expansion anchor rod (7) is set in a direction perpendicular to the rock surface, and the setting spacing matches the spacing of the vertical support steel frame (10); The additional portal primary support system is connected to the cantilever type station tunnel primary support (1) via a vertical support steel frame (10); The construction method includes the following steps: Step (1): Excavation of the variable section of the station tunnel at the interface of the auxiliary cross passage: The station tunnel is excavated normally to a point ≥1.5m outside the outer contour of the additional portal. Based on the span height of the additional portal at the interface of the auxiliary cross passage, the primary support (1) of the cantilevered station tunnel is expanded at the primary support straightening point (8) of the cantilevered station tunnel. The arc line of the arch of the station tunnel on one side of the additional portal is adjusted to the primary support vertical wall (4). The excavation width is expanded to ensure that the primary support system of the additional portal does not invade the subsequent secondary lining (5) of the station tunnel. The cantilevered station tunnel primary support (1) and the primary support vertical wall (4) are driven into the cantilevered station tunnel primary support shell anchor (7). Step (2): construct an additional portal on the inner side of the auxiliary cross channel interface and install advance support: On the inner side of the primary support vertical wall (4) and below the primary support (1) of the cantilevered plate type station tunnel, multiple additional portal steel frames (3) are erected, a vertical support steel frame (10) is erected above the additional portal steel frame (3), and an advance support pipe shed (6) is installed, followed by spraying concrete to complete the construction of the additional portal; Step (3): Apply initial support: After the primary support system of the additional portal in step (2) reaches the designed strength, the steel frame of the primary support vertical wall (4) of the station tunnel is cut off along the outer contour of the additional portal and the auxiliary cross passage is excavated in steps to the deformation joint. The steel frame of the auxiliary cross passage is erected in time and the primary support (2) of the auxiliary cross passage is performed. Subsequently, the excavation and support of the lower section of the auxiliary cross passage interface are carried out step by step.

2. The primary support system for the interface of the auxiliary transverse passage of a submerged underground subway station according to claim 1 is characterized by: The length of the advance support pipe shed (6) located above the arch of the station tunnel covers the deformation joint of the auxiliary cross passage interface and is not less than 6m.

3. The primary support system for the interface of the auxiliary transverse passage of a submerged underground subway station according to claim 1 is characterized by: The area below the primary support (1) of the cantilevered plate station tunnel is the primary support excavation range (9) of the cantilevered plate station tunnel. After the primary support (1) of the cantilevered plate station tunnel, the primary support vertical wall (4) and the additional portal at the primary support excavation range (9) of the cantilevered plate station tunnel are completed, the secondary lining (5) of the station tunnel is closely attached to the inner side thereof.

4. The primary support system for the interface of the auxiliary transverse passage of a submerged subway station according to claim 1 is characterized by: In step (1), the station tunnel is excavated normally to a position ≥1.5m outside the outer contour of the additional portal. According to the span height of the additional portal, the primary support (1) of the cantilevered station tunnel is expanded at the primary support straightening point (8) of the cantilevered station tunnel, and the arc line of the arch of the station tunnel on one side of the additional portal is adjusted to the primary support straight wall (4); the additional portal intrudes into the subsequent station tunnel secondary lining (5). After the subsequent auxiliary cross passage interface is successfully constructed, the additional portal is broken and the secondary lining of the main structure of the station tunnel is constructed.

5. The primary support system for the interface of the auxiliary transverse passage of a submerged subway station according to claim 1 or 4, characterized in that: In step (2), each expansion shell anchor rod of the additional portal steel frame (3) is ≥2.

6. The primary support system for the interface of the auxiliary transverse passage of a submerged underground subway station according to claim 1 or 4, characterized in that: In step (1), if the surrounding rock is very poor, the primary support (1) of the cantilevered station tunnel is not constructed, and the cantilevered station tunnel primary support straightening point (8) is expanded outward in an arc shape along the original primary support contour of the station tunnel to ensure that the arch of the station tunnel is stressed and to control settlement.

7. The primary support system for the interface of the auxiliary transverse passage of a submerged underground subway station according to claim 1 or 4, characterized in that: The additional portal steel frames (3) are closely spaced or connected as a whole by welding with longitudinal reinforcements.

8. The primary support system for the interface of the auxiliary transverse passage of a submerged underground subway station according to claim 1 or 4, characterized in that: The advanced support pipe shed (6) adopts a pipe shed with a diameter of 76~108, a wall thickness of 8mm, and a length of not less than 6m, and is supplemented by a small guide tube with a diameter of 42, a wall thickness of 3.5mm, and a length of not less than 3.5m.

9. The primary support system for the interface of the auxiliary transverse passage of a submerged underground subway station according to claim 1 or 4, characterized in that: The additional portal steel frame (3), the primary support wall (4) steel frame, and the vertical support steel frame (10) are grid steel frames made by welding steel bars or steel arch frames made by I-beams.

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