Underground excavation subway station intersection construction method under active constraint condition

Abstract

The invention provides an underground excavation subway station intersection construction method under active constraint conditions. The underground excavation subway station intersection construction method comprises the following steps of preparation and design before construction; pilot tunnels of an upper step and a middle step of the main station are excavated, pre-stressed anchor rods are densely arranged, and primary support is constructed; when the main body tunnel is constructed to the horsehead, steel frames are densified on the two sides of the channel portal in advance, arch frames and connecting ribs are arranged at the top of the channel portal for densification, and the intersection is supported and reinforced; when main body station upper steps and main body station middle step pilot tunnels are excavated, excavation of accessory structure channel upper steps is synchronously carried out, and primary support is immediately carried out on a channel arch part; pilot tunnels of the lower step of the main station and the lower step of the accessory structure channel are excavated synchronously; and the structure is closed, and the secondary lining of the arch wall is constructed. By means of the construction method, frequent support modification and reconstruction in a traditional method are reduced, the construction cost is saved, and meanwhile the situation that a support structure is unstable due to frequent support dismounting and mounting is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of subway station construction, and in particular to a method for constructing a subway station intersection under active constraint conditions. Background Art

[0002] In urban rail transit construction, due to limitations in surface transportation, urban pipelines, and land use issues, underground tunneling has become the mainstream method for constructing urban subway stations. The traditional underground tunnel construction process typically involves excavating and supporting the main station. Then, during the construction of the auxiliary structure passages, the arch supports of the existing main station must be reinforced, and support at the passage intersections must be strengthened. The connecting support structures at these intersections are then removed to allow excavation of the auxiliary structure passages.

[0003] Although the traditional underground excavation station construction method is widely used, it still has the following problems: it may cause significant damage to the existing support structure, prolong the construction period, increase costs, and often require disassembly and assembly of supports at the junction of the station and the passage, which is not only economically inefficient but also easily causes structural instability.

[0004] In light of this, a method for constructing underground subway station intersections under active constraints is proposed, specifically for applications in complex urban geological conditions and densely populated environments. Utilizing active support technology, this method ensures that the surrounding rock can maximize its inherent stability during construction, thereby making the connection process of multiple chambers more stable and safer. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes a method for constructing a dark-cut subway station intersection under active constraint conditions to solve the technical problems raised in the above background technology, that is, the existing construction method may cause significant damage to the existing support structure, prolong the construction period, increase the cost, and the support structure often needs to be disassembled and assembled at the junction of the station and the passage, which not only has low economic benefits but also easily causes structural instability.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for constructing a subway station intersection under active constraint conditions, comprising the following steps:

[0007] Pre-construction preparation and design;

[0008] Excavate pilot tunnels for the upper and middle steps of the main station, densely arrange prestressed anchor rods, and implement initial support;

[0009] When the main tunnel is constructed to the Matou Gate, the steel frames on both sides of the tunnel gate are reinforced in advance, the arch frame and connecting reinforcement are installed on the top of the tunnel gate to reinforce it, and the intersection is supported and strengthened;

[0010] When excavating the upper steps of the main station and the pilot tunnel of the middle steps of the main station, the upper steps of the auxiliary structure passage will be excavated simultaneously, and the initial support of the passage arch will be immediately implemented;

[0011] Simultaneously excavate the pilot tunnels for the lower steps of the main station and the auxiliary structure passage; and

[0012] Close the structure and carry out secondary lining of the arch wall.

[0013] In a preferred embodiment, the preparation and design before construction include:

[0014] Design support system based on survey data, determine configuration of prestressed anchors and arch supports, and thickness and strength of shotcrete layer;

[0015] The design calculation method of prestressed anchor rod is:

[0016] Preliminary setting parameters: the initial prestress value should be 50% to 80% of the tensile yield strength of the prestressed anchor rod, the diameter of the prestressed anchor rod should be 20mm to 28mm, the length of the prestressed anchor rod should cover the plastic zone of the surrounding rock, and the neutral point should be selected to be larger than the anchor radius of the prestressed anchor rod;

[0017] Calculate the minimum support resistance required for the surrounding rock sliding body and the resistance that the surrounding rock and support structure can provide:

[0018] P min =k·S·γ

[0019] P′=P0+P1+P2+P3

[0020] Among them, k is the horizontal force coefficient of surrounding rock, S is the area of surrounding rock sliding body, γ is the bulk density of rock and soil; P0, P1, P2, P3 are the support resistances that surrounding rock, prestressed anchor, shotcrete and arch frame can provide respectively. N is the axial force of the prestressed anchor rod, e is the longitudinal spacing of the prestressed anchor rod, and t is the circumferential spacing of the prestressed anchor rod;

[0021] Determine the shear force T of the prestressed anchor on the slip surface, which is formed by the axial force N and the shear surface resistance Q. The shear force is expressed as:

[0022]

[0023] Among them, A m is the cross-sectional area of the prestressed anchor rod, f y is the yield strength of the prestressed anchor;

[0024] Verify the shear stress and tensile stress of prestressed anchor rods:

[0025]

[0026] Among them, τ m is the shear stress of the prestressed anchor, σ m is the tensile stress of the prestressed anchor rod; τ m ≤τ t And σ m ≤σ t When τ t is the shear strength of prestressed anchor rod, σ t is the tensile strength of the prestressed anchor rod. The axial tensile and shear properties of this prestressed anchor rod meet the design requirements.

[0027] In a preferred embodiment, the specific steps of supporting and strengthening the intersection are:

[0028] When the main station tunnel is excavated to the intersection with the auxiliary passage, a small advance guide tube is driven into the main tunnel arch footing point along the excavation outline; and

[0029] Locking anchor rods are set at the footing points of the main station tunnel arch frame along the opening outline, and connecting reinforcements are set on both sides of the locking anchor rods and on the inner side of the arch frame.

[0030] In a preferred embodiment, the specific steps of implementing the initial support for the channel arch are:

[0031] When the main structure support and reinforced ring beam support of the interface range between the main body and the auxiliary passage and the area not less than 9m outside the range reach the design strength, multiple steel frames can be erected at the intersection opening, and a layer of connecting reinforcement can be arranged inside and outside the top of the passage opening to increase the strength; and

[0032] The step method is used to excavate the channel reinforcement section, and prestressed anchor rods are also laid on the wall of the auxiliary structure channel.

[0033] In a preferred embodiment, after the prestressed anchor rods are laid, a high-strength concrete layer is sprayed on the wall of the auxiliary structure channel.

[0034] In a preferred embodiment, when excavating the intersection of the upper step of the main station and the pilot tunnel of the middle step of the main station, a breaker hammer is used for precise excavation.

[0035] In a preferred embodiment, during the excavation of the intersection, the channel arch frames are erected one by one to ensure that the channel steel frame is welded to the prestressed anchor rods and forms an integrated structure with the station primary support arch frame through connecting reinforcement. Once the channel steel frame at the intersection is completely closed into a ring, the next cycle of excavation work will be continued.

[0036] In a preferred embodiment, when the pilot tunnels of the lower steps of the main station and the lower steps of the auxiliary structure channel are excavated simultaneously, locking anchor rods are used to fix the arch frame feet of the main station tangent to the arc. After the pilot pit on one side of the step in the main tunnel is excavated and initial support is applied, the rock layer of the step under the auxiliary structure channel is excavated and initial support is applied in a timely manner.

[0037] In a preferred embodiment, when the excavation of the lower steps of the main station and the lower steps of the auxiliary structure passage are carried out simultaneously, the length of the advance at one time is not greater than the width of one steel frame.

[0038] In a preferred embodiment, the specific steps of closing the structure and constructing the secondary lining of the arch wall are:

[0039] Excavate the pilot tunnel under the main station steps and close the initial support between the main station and the auxiliary structure passage;

[0040] Laying the invert water layer and pouring the secondary lining of the tunnel invert wall; and

[0041] Lay the arch wall waterproof layer, and pour the secondary lining and internal structure of the arch wall of the main station and the auxiliary structure passage.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The present invention provides a method for constructing subway station intersections under active constraints. By continuously excavating the main station and ancillary structure passages simultaneously, this method allows for simultaneous construction of the main tunnel and ancillary structure passages, effectively reducing the total construction time. Furthermore, timely implementation of initial support and reinforcement measures accelerates the project process, improves construction efficiency, and reduces the need for repeated support and disassembly at key locations such as intersections. By establishing a strong support structure once and for all, the frequent support modifications and reconstructions required in traditional methods are reduced. This not only saves material costs, but also reduces labor and management costs, improving economic efficiency. It also avoids instability in the support structure caused by frequent support disassembly and assembly, thereby improving construction safety.

[0044] 2. The present invention provides a method for constructing a subway station intersection under active constraints. A detailed geological survey is conducted in the early stages of construction, and a support system is designed based on the survey data, as well as precise calculations of prestressed anchor rods, to ensure that sufficient prestress can be applied before excavation, thereby actively constraining the surrounding rock. This active constraint greatly enhances the stability of the surrounding rock at the intersection and reduces structural safety risks caused by geological uncertainties. Active support technologies such as prestressed anchor rods and sprayed high-strength concrete layers are also used. Advance small guide tubes are used to reinforce the strata at key nodes such as intersections. The support structure is strengthened by using multiple steel frames and closely spaced arches, further reducing safety risks during construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the specific embodiments. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0046] Figure 1 A longitudinal section diagram of the intersection construction between the auxiliary structure passage and the main station structure in a method for constructing a subway station intersection under active constraints provided by the present invention;

[0047] Figure 2 This is a cross-sectional view of the intersection construction of the auxiliary structure passage and the main station structure in a method for constructing a subway station intersection under active constraints according to the present invention;

[0048] Figure 3 This is a schematic diagram of the connection structure between the steel frame and the locking foot anchor rods in a concealed excavation subway station intersection construction method under active constraint conditions of the present invention.

[0049] Reference numerals:

[0050] 1. Prestressed anchor rods; 2. Advance small guide tubes; 3. Concrete layer; 4. Reinforced concrete secondary lining; 5. Reinforced ring beam; 6. Crossbeam column; 7. Locking anchor rods; 8. Upper steps of the main station; 9. Upper steps of the auxiliary structure passage; 10. Steel frame; 11. Connecting reinforcement; 12. Arch frame; 13. Middle steps of the main station; 14. Lower steps of the auxiliary structure passage; 15. Lower steps of the main station; 16. Secondary lining of the arch wall. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above application content.

[0052] Example:

[0053] like Figures 1 to 3 As shown, the present invention provides a method for constructing a subway station intersection under active constraint conditions, comprising the following steps:

[0054] Pre-construction preparation and design begin. This includes designing the support system based on the survey data, determining the configuration of the prestressed anchor rods 1 and arch supports 12, and determining the thickness and strength of the shotcrete layer 3. Selecting the appropriate type of prestressed anchor rod 1 based on the survey data ensures that the prestressed anchor rod 1 can provide sufficient prestress before excavation to actively constrain the surrounding rock and enhance structural safety.

[0055] The design calculation method of prestressed anchor rod 1 is:

[0056] Preliminary setting parameters: the initial prestress value should be 50% to 80% of the tensile yield strength of the prestressed anchor rod 1, the diameter of the prestressed anchor rod 1 should be 20mm to 28mm, the length of the prestressed anchor rod 1 should cover the plastic zone of the surrounding rock, and the neutral point position should be larger than the anchoring radius of the prestressed anchor rod 1 and be in an appropriate position;

[0057] Calculate the minimum support resistance required for the surrounding rock sliding body and the resistance that the surrounding rock and support structure can provide:

[0058] P min =k·S·γ

[0059] P′=P0+P1+P2+P3

[0060] Among them, k is the horizontal force coefficient of surrounding rock, S is the area of surrounding rock sliding body, γ is the bulk density of rock and soil; P0, P1, P2, P3 are the support resistances that surrounding rock, prestressed anchor 1, shotcrete, and arch frame 12 can provide respectively. N is the axial force of prestressed anchor rod 1, e is the longitudinal spacing of prestressed anchor rod 1, and t is the circumferential spacing of prestressed anchor rod 1;

[0061] Since the support resistance provided by the prestressed anchor rod 1 is very small, according to P′>P min The design of prestressed anchor rods is not fully considered, and the shear performance requirements of prestressed anchor rods 1 need to be further considered.

[0062] According to the neutral point theory of prestressed anchor 1, the location of the neutral point of prestressed anchor 1 determines the distribution of support force. When prestressing, increasing the prestress in prestressed anchor 1 shifts the neutral point toward the end of prestressed anchor 1, increasing both the axial force and support resistance in direct proportion. Increasing the diameter of prestressed anchor 1 shifts the neutral point toward the end of prestressed anchor 1, also increasing both the axial force and support resistance in direct proportion.

[0063] Determine the shear force T of the prestressed anchor 1 on the slip surface, which is formed by the axial force N and the shear surface resistance Q. The shear force is expressed as:

[0064]

[0065] Among them, A m is the cross-sectional area of the prestressed anchor rod 1, f y is the yield strength of prestressed anchor rod 1;

[0066] Verify the shear stress and tensile stress of prestressed anchor rod 1:

[0067]

[0068] Among them, τ m is the shear stress of prestressed anchor 1, σ m is the tensile stress of the prestressed anchor rod 1; τ m ≤τ t And σ m ≤σ t When τ t is the shear strength of prestressed anchor rod 1, σ t is the tensile strength of the prestressed anchor rod 1. The axial tensile and shear resistance of the prestressed anchor rod 1 meet the design requirements.

[0069] If the verification fails, it is necessary to adjust the parameters (increase the diameter of the prestressed anchor rod 1 or the size of the prestress, etc.) and repeat the above steps until the support requirements are met.

[0070] Then, pilot tunnels are excavated for the upper step 8 of the main station and the middle step 13 of the main station, prestressed anchor rods 1 are densely arranged, and initial support is applied. The prestressed anchor rods 1 are densely arranged in a plum blossom shape to ensure the stability of the excavation surface.

[0071] When the main tunnel is constructed to the horse head gate, the steel frames 10 on both sides of the tunnel portal are reinforced in advance, and the arch frame 12 and connecting reinforcement 11 are set on the top of the tunnel portal to reinforce it. The intersection is also supported and reinforced. The specific steps for supporting and strengthening the intersection are as follows: When the main station tunnel is excavated to the intersection with the auxiliary channel, an advance small guide tube 2 is driven into the footing point of the main tunnel arch frame 12 along the opening contour line to reinforce the stratum at the intersection. Pay attention to controlling the longitudinal spacing of the rings and the external insertion angle of about 10 degrees. In addition, locking anchor rods 7 are set at the footing point of the main station tunnel arch frame 12 along the opening contour line, and connecting reinforcement 11 is set on both sides of the locking anchor rod 7 and on the inner side of the arch frame 12.

[0072] While excavating the pilot tunnels for the main station upper step 8 and the main station middle step 13, the upper step 9 of the auxiliary structure passageway was excavated simultaneously, and initial support for the passageway arch was immediately implemented. The specific steps for implementing initial support for the passageway arch are as follows: Once the main structure support and the reinforcement ring beam 5 within the interface between the main and auxiliary passageways, and for at least 9 meters beyond, reach their designed strength, multiple steel frames 10 can be erected at the intersection opening. A layer of connecting reinforcement 11 is installed inside and outside the top of the passageway portal for reinforcement. The reinforced section of the passageway is excavated using the step method, and prestressed anchor bolts 1 are also installed on the walls of the auxiliary structure passageway. After the prestressed anchor bolts 1 are installed, a layer of high-strength concrete 3 is sprayed on the walls of the auxiliary structure passageway to form an effective active support system.

[0073] like Figure 1 、 2As shown, in this embodiment, a breaker hammer is used for precise excavation during the intersection of the pilot tunnels for the upper step 8 and the middle step 13 of the main station. During the excavation of the intersection, the channel arch frames 12 are erected one by one, ensuring that the channel steel frame 10 is welded to the prestressed anchor rods 1 and integrated with the station primary support arch frame 12 through connecting bars 11. This ensures that the steel frame 10 and the arch frame 12 are jointly stressed, enhancing the overall stability of the structure. Once the channel steel frame 10 at the intersection is completely closed into a loop, the next cycle of excavation is continued.

[0074] During the simultaneous excavation of the pilot tunnels for the lower steps 15 of the main station and the lower steps 14 of the auxiliary structure passage, locking anchor rods 7 were used to secure the arch frame 12, which is tangential to the arc, on both sides of the main station. After the pilot pit on the step side of the main tunnel was excavated and initial support was applied, the rock layer under the lower steps 14 of the auxiliary structure passage was excavated and initial support was applied promptly. During the simultaneous excavation of the pilot tunnels for the lower steps 15 of the main station and the lower steps 14 of the auxiliary structure passage, the length of the single advance was no more than the width of one steel frame 10.

[0075] Finally, the structure is closed and the secondary arch lining 16 is constructed. The specific steps for this construction are: excavating the pilot tunnel beneath the main station steps 15, closing the initial support for the main station and the auxiliary structure passage, laying the inverted arch water layer, pouring the secondary arch lining 16 of the tunnel inverted arch, and finally laying the arch wall waterproofing layer. The secondary arch lining 16 and internal structure of the main station and the auxiliary structure passage are poured. Furthermore, a reinforced concrete secondary lining 4 is poured within the main station, connected to the auxiliary structure passage via crossbeams 6, further reinforcing the intersection structure.

[0076] Specific usage and beneficial effects of the present invention:

[0077] The present invention provides a method for constructing subway station intersections under active constraints. By simultaneously excavating the main station and the auxiliary structure passageways, this method allows for simultaneous construction of the main tunnel and the auxiliary structure passageways, effectively reducing the total construction time. Furthermore, timely implementation of initial support and reinforcement measures accelerates the project process, improves construction efficiency, and reduces the need for repeated support and disassembly at key locations such as intersections. By establishing a strong support structure once and for all, the frequent support modifications and reconstructions required in traditional methods are reduced. This not only saves material costs, but also reduces labor and management costs, improving economic efficiency. It also avoids instability in the support structure caused by frequent support disassembly and assembly, thereby enhancing construction safety.

[0078] The present invention provides a method for constructing a subway station intersection under active constraints. A detailed geological survey is conducted in the early stages of construction, and a support system is designed based on the survey data, as well as accurate calculations of the prestressed anchor rods 1, to ensure that sufficient prestress can be applied before excavation, thereby actively constraining the surrounding rock. This active constraint greatly enhances the stability of the surrounding rock at the intersection and reduces structural safety risks caused by geological uncertainties. Active support technologies such as prestressed anchor rods 1 and high-strength concrete layers 3 are used, and advanced small guide tubes 2 are used to reinforce the stratum at key nodes such as intersections. The support structure is strengthened by closely spaced multiple steel frames 10 and arch frames 12, further reducing safety risks during construction.

[0079] The basic principles, main features, and advantages of the present invention are shown and described above. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above. Modifications and improvements may be made based on the present invention, as will be apparent to those skilled in the art. Therefore, such modifications and improvements, without departing from the spirit of the present invention, are intended to fall within the scope of protection claimed in the present invention.

Claims

1. A construction method for a subway station intersection under active constraint conditions, characterized in that: The following steps are included: Pre-construction preparation and design; Excavate pilot tunnels for the upper step (8) and the middle step (13) of the main station, densely arrange prestressed anchor rods (1), and apply initial support; When the main tunnel is constructed to the horse head gate, the steel frames (10) are reinforced on both sides of the tunnel gate in advance, the arch frame (12) and the connecting reinforcement (11) are set on the top of the tunnel gate to reinforce it, and the intersection is supported and strengthened; When excavating the pilot tunnels of the upper steps (8) and the middle steps (13) of the main station, the upper steps (9) of the auxiliary structure channel are excavated simultaneously, and the initial support of the channel arch is immediately implemented; Simultaneously excavate the pilot tunnels for the lower steps (15) of the main station and the lower steps (14) of the auxiliary structure passage; and The structure is closed and the secondary lining (16) of the arch wall is carried out.

2. The method for constructing a subway station intersection under active constraints according to claim 1 is characterized in that: The pre-construction preparation and design include: Based on the survey data, the support system is designed to determine the configuration of the prestressed anchor rods (1), the arch frame (12), and the thickness and strength of the shotcrete layer (3); The design calculation method of prestressed anchor rod (1) is: Preliminary setting parameters: the initial prestress value should be 50% to 80% of the tensile yield strength of the prestressed anchor rod (1); the diameter of the prestressed anchor rod (1) should be 20 mm to 28 mm; the length of the prestressed anchor rod (1) should cover the plastic zone of the surrounding rock; and the neutral point position should be selected to be larger than the anchoring radius of the prestressed anchor rod (1); Calculate the minimum support resistance required for the surrounding rock sliding body and the resistance that the surrounding rock and support structure can provide: P min =k·S·γ P′=P0+P1+P2+P3 Where k is the horizontal force coefficient of the surrounding rock, S is the area of the surrounding rock sliding body, γ is the bulk density of the rock and soil; P0, P1, P2, and P3 are the support resistances that the surrounding rock, prestressed anchor (1), shotcrete, and arch frame (12) can provide, respectively. N is the axial force of the prestressed anchor rod (1), e is the longitudinal spacing of the prestressed anchor rod (1), and t is the circumferential spacing of the prestressed anchor rod (1); The shear force T of the prestressed anchor (1) on the slip surface is determined by the axial force N and the shear surface resistance Q. The shear force is expressed as: Among them, A m is the cross-sectional area of the prestressed anchor rod (1), f y is the yield strength of the prestressed anchor (1); Verify the shear stress and tensile stress of prestressed anchor rod (1): Among them, τ m is the shear stress of the prestressed anchor (1), σ m is the tensile stress of the prestressed anchor rod (1); τ m ≤τ t And σ m ≤σ t When τ t is the shear strength of the prestressed anchor (1), σ t The tensile strength of the prestressed anchor rod (1) is such that the axial tensile and shearing properties of the prestressed anchor rod (1) meet the design requirements.

3. The method for constructing a subway station intersection under active constraints according to claim 1 is characterized in that: The specific steps of supporting and strengthening the intersection are: When the main station tunnel is excavated to the intersection with the auxiliary passage, a small advance guide tube (2) is driven into the landing point of the main tunnel arch (12) along the opening outline; and A locking anchor rod (7) is provided at the landing point of the main station tunnel arch frame (12) along the opening outline, and connecting ribs (11) are provided on both sides of the locking anchor rod (7) and the inner side of the arch frame (12).

4. The method for constructing a subway station intersection under active constraints according to claim 1 is characterized in that: The specific steps of implementing the initial support for the tunnel arch are: When the main structure support and the reinforced ring beam (5) support within the interface range between the main body and the auxiliary channel and the area not less than 9m outside the range reach the design strength, multiple steel frames (10) can be erected at the intersection opening, and a layer of connecting reinforcement (11) can be arranged inside and outside the top of the channel door for reinforcement; and The step method is used to excavate the channel reinforcement section, and prestressed anchor rods (1) are also arranged on the wall of the auxiliary structure channel.

5. The method for constructing a subway station intersection under active constraints according to claim 4, characterized in that: After the prestressed anchor rods (1) are laid, a high-strength concrete layer (3) is sprayed on the wall of the auxiliary structure channel.

6. The method for constructing a subway station intersection under active constraints according to claim 5, characterized in that: When excavating the intersection of the upper step (8) of the main station and the pilot tunnel of the middle step (13) of the main station, a breaker hammer is used for precise excavation.

7. The method for constructing a subway station intersection under active constraints according to claim 6, characterized in that: During the excavation of the intersection, the channel arch frame (12) is erected one by one to ensure that the channel steel frame (10) is welded to the prestressed anchor rod (1) and forms an integrated structure with the station primary support arch frame (12) through the connecting reinforcement (11). Once the channel steel frame (10) at the intersection is completely closed into a ring, the excavation work of the next cycle will be continued.

8. The method for constructing a subway station intersection under active constraints according to claim 1, characterized in that: When the pilot tunnels of the lower step (15) of the main station and the lower step (14) of the auxiliary structure passage are excavated simultaneously, the foot locking anchor rods (7) are used to fix the arch frame (12) of the main station tangent to the arc on both sides. After the pilot tunnel excavation on one side of the step in the main tunnel is completed and the initial support is applied, the rock layer of the lower step (14) of the auxiliary structure passage is excavated and the initial support is applied in time.

9. The method for constructing a subway station intersection under active constraints according to claim 8, characterized in that: When the excavation of the pilot tunnels of the lower steps (15) of the main station and the lower steps (14) of the auxiliary structure passage is carried out simultaneously, the length of the single advance is not greater than the width of one steel frame (10).

10. The method for constructing a subway station intersection under active constraints according to claim 1, characterized in that: The specific steps of constructing the closed structure and performing the secondary lining (16) of the arch wall are as follows: Excavate the pilot tunnel under the main station steps (15) and close the initial support between the main station and the auxiliary structure passage; Laying the inverted arch water layer and pouring the secondary lining of the tunnel inverted arch wall (16); and Lay the arch wall waterproof layer, and pour the arch wall secondary lining (16) and internal structure of the main station and auxiliary structure passage.

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