Urban subway construction method for firstly connecting channel and then shield main tunnel

Abstract

The invention provides an urban subway construction method with a contact channel firstly and a shield main tunnel secondly. The urban subway construction method comprises the following steps that S1, the excavation position, depth and size information of the contact channel is determined; s2, underground excavation is conducted on the vertical shaft to the preset depth of the connection channel, and vertical shaft supports are constructed; s3, the contact channel is transversely excavated in an underground mode, and primary support is completed in the excavation process; s4, the shield tunneling machine shields the main tunnel, and temporary tunnel supports are constructed; and S5, lining construction is conducted on the connecting channel, and the connecting channel is reinforced. According to the urban subway construction method with the contact channel firstly and then the shield main tunnel, the mode that the contact channel is firstly constructed and then the shield main tunnel is adopted, the main tunnel cannot be disturbed by construction of the contact channel, and the stability of the main tunnel is guaranteed; the connecting passages and the vertical shafts can be used as passages or safety passages for material transportation, so that material transportation and personnel access during construction and emergency are facilitated; and the convenience of multi-layer channel construction is improved.

Description

Technical Field

[0001] The invention relates to the field of urban rail transit, and in particular to an urban subway construction method which constructs a connecting channel first and then a shield main tunnel. Background Art

[0002] At present, in order to ease the pressure of ground traffic and improve the travel environment for residents, and at the same time promote the prosperity and development of the entire social economy, a large number of urban rail transit constructions are also facing the challenges of construction technology difficulties. In order to ensure that the subway tunnel can safely and quickly evacuate passengers in an emergency, a horizontal communication channel needs to be set up between the two subway tunnels. At the same time, the communication channel can also play the role of tunnel drainage, fire prevention and fire fighting.

[0003] According to the "Metro Design Code" (GB50157-2013), a connecting channel should be set up between two single-track section tunnels, and the distance between two adjacent connecting channels should not be greater than 600m. For long-distance subway lines, the number of connecting channels is large and the cost is high.

[0004] At present, the construction methods of urban subway section connection channels mainly adopt mining method, freezing method and mechanical method: The mining method is to use manual or mechanical excavation for the connecting channel based on the principle of the New Austrian Tunneling Method after the two single-line shield sections are completed, and adopt the construction method of steel arch initial support and concrete secondary lining. This method has a long construction period, low efficiency, high ground reinforcement cost, will have a certain impact on the surrounding environment, and the working environment is not friendly to the construction workers; The freezing method is actually a variant of the mining method. Before manual excavation, the soil needs to be frozen so that the loose soil forms a certain freezing circle. This method requires a lot of freezing time and is not applicable to flowing sand layers. The mechanical method also requires the completion of two single-line shield sections first, and the use of a micro-shield machine to break the segments of the main tunnel (using fiberglass reinforced steel bars), and then advance the shield until it passes through the other main tunnel. This method can only construct circular cross-section tunnels, and there are construction restrictions on connecting channels with water collection wells. The T-joint structure where the connecting channel intersects the main tunnel structure is subject to complex stress and deformation, and has disadvantages such as water leakage.

[0005] It can be seen that no matter the mining method, freezing method or mechanical method, when constructing the connecting channel, it is necessary to first penetrate the two shield main tunnels, which increases the overall construction period. At the same time, the construction of the connecting channel will also cause disturbances to the main tunnel, and mechanical construction will also hinder the material transportation of the main tunnel. Especially in the process of multi-layer tunnel construction, the construction and connection of the connecting passage is more troublesome, and the material transportation and ventilation during the lower layer construction are more unstable; In addition, during and after the construction process, emergency escape passages need to be set up. However, the construction method of first building the main tunnel and then the communication passage results in fewer emergency passages. In addition, adding a second or multi-story passage also requires re-excavation, which is time-consuming and labor-intensive. Summary of the invention

[0006] The main purpose of the present invention is to provide a method for constructing an urban subway by first constructing a connecting passage and then shielding a main tunnel, so as to solve the problem of first shielding a main tunnel and then constructing a connecting passage, which causes construction inconvenience.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for constructing an urban subway by first constructing a communication channel and then a shield main tunnel comprises the following steps: Step S1, determining the location, depth and size information of the communication channel excavation; Step S2, before the main tunnel is excavated, the vertical shaft is secretly excavated to a predetermined depth of the communication channel, and the vertical shaft support is applied; Step S3, digging a lateral communication channel and completing initial support during the digging process; Step S4, the shield machine constructs the main tunnel and performs temporary tunnel support; Step S5, lining the communication channel to reinforce the communication channel; Through the above steps, the construction of the communication channel can be quickly completed.

[0008] In a preferred solution, the initial support includes mortar anchor rods, grouting anchor rods and steel support. When the lining of the communication channel is constructed, the steel support is removed.

[0009] In a preferred solution, in step S3, it also includes: Step S31, expanding the bell mouth in the shield area of ​​the main tunnel at the end of the communication channel, and providing support; Step S32, construct a temporary safety door between the bell mouth and the communication channel; Step S33, removing the support of the bell mouth and filling the bell mouth with lightweight foam concrete; After step S4 is completed, some shield segments close to the safety door are removed, and then the safety door and temporary support are removed, and finally secondary lining construction is carried out for reinforcement.

[0010] In a preferred solution, during the construction process, a wellhead transport machine is arranged above the shaft for the entry and exit of construction materials and machinery and the transport out of excavated waste; A construction elevator is installed in the shaft for construction workers to enter and exit.

[0011] In the preferred solution, during the shield construction of the main tunnel, the required materials are delivered through the nearest communication channel and shaft, and the construction workers can also enter and exit through the nearest communication channel and shaft; There is a difference of 1-2 construction periods between the shield construction of the main tunnel and the connecting channel, that is, the connecting channels are constructed sequentially according to the line, and the shield construction of the main tunnel starts after the construction of the first connecting channel is completed.

[0012] In the preferred solution, the position of the underground excavated shaft is laterally offset at a predetermined position, and after digging to a sufficient depth, the transfer channel is then horizontally excavated to the predetermined position of the communication channel, and then the communication channel is further horizontally excavated; After the construction is completed, a prefabricated emergency passage connecting the transfer passage and the ground will be set up in the shaft as needed, and emergency doors that can be opened in an emergency will be set at both ends of the prefabricated emergency passage.

[0013] In a preferred solution, a protective door is provided at the connection between the transfer channel and the communication channel; A storage room is dug inside the transfer channel to store emergency rescue tools and construction materials.

[0014] In the preferred solution, excavation is continued at the shaft position to reach the excavation position of the second-layer main tunnel, shaft support is applied, and then steps S3, S4 and S5 are repeated to complete the construction of the second-layer tunnel. The construction of the second-layer tunnel does not affect the completed tunnel.

[0015] In a preferred solution, an emergency passage is dug obliquely between the transfer passage and the ground, and emergency doors that are opened in an emergency are provided at both ends of the emergency passage; The emergency passage is connected to the vertical shaft, which serves as a ventilation passage.

[0016] In the preferred solution, after the construction is completed, the step of setting up a prefabricated emergency passage is also included: Step S61, according to the depth of the shaft, use a crane to lower multiple tubes, and set ladders in the tubes, and the ladders in the upper and lower adjacent tubes are connected; Step S62, a first doorway is opened at the junction of the tube and the transfer channel; Step S63, cover the top of the uppermost tube with a pipe cover, the pipe cover should be at least 3 meters above the ground, and the pipe cover should be backfilled into the shaft; Step S64, digging a safety passage from the ground side to the bottom of the pipe cover, opening a second door hole at the connection between the pipe cover and the safety passage, and the second door hole is connected to the ladder; Step S65, constructing emergency doors at the first door opening and the second door opening; Among them, a first door hole is provided on the side of the tube connected to the communication channel, a second door hole is provided on the side of the tube cover, a spiral staircase is provided on the inner wall of the tube, a platform is provided at the top of the staircase in the same tube, and a railing is provided at one end of the staircase and the platform away from the inner wall of the tube. Between two adjacent tubes, the platform is connected to the staircase, the first door hole is connected to the staircase, and the second door hole is connected to the platform; The bottom ends of the inner walls of the tube and the tube cover are both fixed with plug-in tubes, which are inserted into the tube below; The top of the inner wall of the tube and the top of the tube cover are both fixed with connecting rings for lifting; The outer side walls of the tube and the tube cover are provided with an anti-corrosion coating.

[0017] In the preferred solution, the excavation is continued at the shaft position to reach the excavation position of the second-layer main tunnel, and then steps S3, S4 and S5 are repeated to complete the construction of the second-layer tunnel; When constructing the second-level tunnel, if it is constructed at the same time as the first-level tunnel, the emergency passage will be constructed after the communication passage and the main tunnel at the same shaft location are completed; If a second-layer passage is added later, the backfill on the pipe cover can be dug out, and then the pipe cover and pipe tube can be lifted one by one, and then the second-layer excavation construction can be continued. After completion, the emergency passage can be reconstructed.

[0018] The present invention provides a method for constructing an urban subway by first constructing a communication channel and then a shield main tunnel, and the beneficial effects are as follows: 1. The method of constructing the connecting channel first and then shielding the main tunnel is adopted. The main tunnel will not be disturbed by the construction of the connecting channel, thus ensuring the stability of the main tunnel.

[0019] 2. Communication passages and shafts can be used as channels for transporting materials or safety passages, facilitating the transportation of materials and the entry and exit of personnel during construction and emergencies. They can also be used as ventilation passages.

[0020] 3. Setting up prefabricated emergency passages is not only simple to set up and more efficient, but also makes it easier for people to enter and exit.

[0021] 4. This application facilitates the construction of multi-layer communication channels and shield main tunnels at the same time, and also facilitates the subsequent addition of multi-layer communication channels and shield main tunnels, thereby increasing the convenience of multi-layer channel construction and solving the problem of inconvenient construction of multi-layer tunnels. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a structural schematic diagram of a method for constructing a city subway after the construction of a tunnel of the first layer according to the present invention, which comprises a connecting passage first and then a shield main tunnel; Figure 2It is a structural schematic diagram of a method for constructing a city subway by first constructing a communication channel and then a shield tunnel after the second-layer tunnel is constructed; Figure 3 It is a schematic diagram of the structure of the communication channel after construction of the present invention; Figure 4 It is a schematic diagram of the structure of the main channel after the shield tunneling of the present invention; Figure 5 It is a schematic diagram of the structure of an embodiment of the construction of the communication channel of the present invention; Figure 6 It is a structural schematic diagram of the prefabricated emergency passage of the present invention; Figure 7 It is a structural schematic diagram of the prefabricated emergency passage of the present invention; Figure 8 It is a front view cross-sectional structural schematic diagram of the prefabricated emergency passage of the present invention; Fig. 9 It is a schematic diagram of the rear cross-sectional structure of the prefabricated emergency passage of the present invention; Fig.10 It is a side view cross-sectional structural schematic diagram of the prefabricated emergency passage of the present invention; Fig.11 1 is a schematic diagram of the structure of an embodiment of the emergency passage of the present invention; Fig.12 It is a schematic diagram of the prefabricated emergency passage of the present invention during hoisting.

[0023] In the figure: Tube 1, first door opening 101, tube cover 2, second door opening 201, ladder 3, platform 4, railing 5, plug-in tube 6, connecting ring 7; Vertical shaft 11, vertical shaft support 12, steel support 13, initial support 14, shaft head transport machinery 15, safety door 16, bell mouth 17, lightweight foam concrete 18, main tunnel 20, temporary support 21, lining 22, connecting channel 30, first-floor connecting channel axis 41, second-floor connecting channel axis 42, transfer channel 50. DETAILED DESCRIPTION

[0024] Embodiment 1: like Figure 1 , 3 As shown in Figure 4, a method for constructing an urban subway by first constructing a communication channel and then a shielding main tunnel comprises the following steps: Step S1, determining the location, depth and size information of the excavation of the communication channel 30; Step S2, before the main tunnel 20 is excavated, the vertical shaft 11 is secretly excavated to a predetermined depth of the communication passage 30, and the vertical shaft support 12 is applied; Step S3, excavating the communication channel 30 transversely and completing the initial support 14 during the excavation process; Step S4, the shield machine constructs the main tunnel 20 and performs temporary tunnel support 21; Step S5, constructing the lining 22 of the communication channel 30 to reinforce the communication channel 30; The construction of the communication channel 30 is quickly completed through the above steps.

[0025] The first-layer communication channel axis 41 and the second-layer communication channel axis 42 are used to illustrate the excavation positions of the communication channels, and the specific positions are determined according to actual conditions.

[0026] During the construction process, by constructing the connecting channel 30 first and then shielding the main tunnel 20, the main tunnel 20 is formed later and will not be disturbed by the construction of the connecting channel 30. In addition, the connecting channel 30 can be used as a channel for material transportation and ventilation, which is more convenient during the construction of the main tunnel 20.

[0027] In a preferred solution, the initial support 14 includes mortar anchor rods, grouting anchor rods and steel support rods 13. When the lining 22 of the communication channel 30 is constructed, the steel support rods 13 are removed.

[0028] In a preferred solution, in step S3, it also includes: Step S31, in the shield area of ​​the main tunnel 20 at the end of the communication channel 30, the bell mouth 17 is expanded and supported, the bell mouth 17 is within the shield range of the main tunnel 20, and the shield machine passes through the bell mouth 17; Step S32, constructing a temporary safety door 16 between the bell mouth 17 and the communication channel 30; Step S33, removing the support of the bell mouth 17, and filling the position of the bell mouth 17 with lightweight foam concrete 18 for reinforcement, and the safety door 16 can close the lightweight foam concrete 18; After step S4 is completed, some shield segments close to the safety door 16 are removed, and then the safety door 16 and temporary support 22 are removed, and finally the secondary lining 22 is constructed for reinforcement.

[0029] By adopting the reinforcement method of foam concrete 18, the supporting effect can be guaranteed and the subsequent processing can be facilitated, such as the subsequent shield processing.

[0030] In a preferred solution, during the construction process, a wellhead transport machine 15 is arranged above the shaft 11. The wellhead transport machine 15 includes a gantry crane or a lift, etc., which is used for the entry and exit of construction materials and machinery and the transport out of excavated waste, greatly shortening the transport distance; A construction elevator is provided in the shaft 11 for construction workers to enter and exit.

[0031] During the subsequent construction process, construction workers can choose to enter and exit the vertical shaft with an elevator nearby, so that construction workers can enter and exit the tunnel more conveniently and return to the ground faster in the event of an accident.

[0032] In the preferred solution, during the shield tunneling of the main tunnel 20, the required materials are delivered through the nearest communication channel 30 and the shaft 11, and the construction workers can also enter and exit through the nearest communication channel 30 and the shaft 11; There is a difference of 1-2 construction periods between the shield construction of the main tunnel 20 and the connecting channel 30, that is, the connecting channel 30 is constructed sequentially according to the route, and the shield construction of the main tunnel 20 starts after the construction of the first connecting channel 30 is completed, and then the subsequent connecting channels 30 are constructed sequentially, so that the efficiency of construction can be guaranteed while ensuring that the connecting channel 30 is constructed first and then the shield construction of the main tunnel 20.

[0033] Embodiment 2: like Figure 5 As shown, the position of the underground shaft 11 is laterally offset at a predetermined position, and after digging to a sufficient depth, the transfer channel 50 is horizontally excavated to the predetermined position of the communication channel 30, and then the communication channel 30 is continuously horizontally excavated; After the construction is completed, a prefabricated emergency passage connecting the transfer passage 50 and the ground is set up in the shaft 11 as needed, and emergency doors that can be opened in an emergency are set at both ends of the prefabricated emergency passage.

[0034] By setting up the transfer channel 50, it is possible to avoid the vertical shaft 11 being directly connected to the communication channel 30, which is safer during subsequent construction and can also reduce the impact of the construction of the communication channel 30 on the vertical shaft 11. The transfer channel 50 also plays a role of transfer; After the prefabricated emergency passage is set up, it will not be used for normal communication. In case of emergency, the user can directly enter and exit the prefabricated emergency passage through the transfer passage 50.

[0035] In a preferred solution, a protective door is provided at the connection between the transfer channel 50 and the communication channel 30, and the transfer channel 50 and the communication channel 30 are usually isolated, leaving only necessary ventilation holes, and the protective door is opened when necessary. The protective door can be provided with reference to the fire door; A storage room is dug inside the transfer channel 50 for storing emergency rescue tools and construction materials. A fixed storage room is provided to facilitate emergency response at any time.

[0036] Embodiment 3: like Figure 2 As shown, continue digging at the position of the shaft 11 to reach the excavation position of the second-layer main tunnel 20, apply the shaft support 12, and then repeat steps S3, S4 and S5 to complete the construction of the second-layer tunnel. The construction of the second-layer tunnel does not affect the tunnel that has been completed. When constructing the second-floor tunnel, if it is constructed at the same time as the first-floor tunnel, the emergency passage will be constructed after the communication passage 30 and the main tunnel 20 at the same shaft 11 are completed.

[0037] The method of the present application can facilitate the construction of double-layer or even multi-layer tunnels, and the transportation of materials is also more convenient. Not only does it not affect the use of the upper tunnel, but there is no need to find another excavation location, thereby adapting to the construction needs of multi-layer tunnels and solving the problem that it is inconvenient to carry out multi-layer tunnel construction in the prior art.

[0038] Embodiment 4: like Figure 6 , 7 , 8, 9, 10 and 12, after the construction is completed, the steps of setting up a prefabricated emergency passage are also included: Step S61, according to the depth of the shaft 11, use a crane to lower a plurality of tubes 1, a ladder is provided inside the tubes 1, and the ladders in the upper and lower adjacent tubes 1 are connected; Step S62, a first door opening 201 is opened at the junction of the tube 1 and the transfer channel 50; Step S63, cover the top of the uppermost tube 1 with the pipe cover 2, the pipe cover 2 being at least 3 meters above the ground, and backfill the shaft 11 with the pipe cover 2; Step S64, digging a safety passage from the ground side to the bottom of the pipe cover 2, opening a second door hole 202 at the connection between the pipe cover 2 and the safety passage, and the second door hole 202 is connected to the ladder; Step S65, constructing emergency doors at the first door opening 201 and the second door opening 202; Among them, a first door hole 101 is provided on the side of the tube 1 connected to the communication channel 30, a second door hole 201 is provided on the side of the tube cover 2, a staircase 3 is provided on the inner wall of the tube 1 in a spiral shape, a platform 4 is provided at the top of the staircase 3 in the same tube 1, and a railing 5 is provided at one end of the staircase 3 and the platform 4 away from the inner wall of the tube 1. Between two adjacent tubes 1, the platform 4 is connected to the staircase 3, the first door hole 101 is connected to the staircase 3, and the second door hole 201 is connected to the platform 4; The inner wall bottom ends of the tube 1 and the tube cover 2 are both fixed with a plug-in tube 6, which is inserted into the tube 1 below; The top of the inner wall of the tube 1 and the top of the tube cover 2 are both fixed with a connecting ring 7 for lifting; The outer side walls of the tube 1 and the tube cover 2 are both provided with an anti-corrosion coating.

[0039] When in use, the user reaches the transfer channel 50 through the communication channel 30 , then walks to the stairs 3 through the first doorway 101 , then climbs up along the stairs 3 , and finally walks out through the second doorway 201 .

[0040] After the user walks out through the second door opening 201, he can go back to the ground through the safety passage.

[0041] The entire installation process is carried out by crane lifting, which is easy to install and more efficient than existing technologies.

[0042] If a second-layer passage needs to be added later, the backfill on the pipe cover 2 can be dug out, and then the pipe cover 2 and the pipe tube 1 can be lifted one by one, and then the second-layer excavation construction can be continued. After completion, the emergency passage can be reconstructed. It does not need to be damaged during installation and can be directly taken out and reused, reducing waste.

[0043] Embodiment 5: like Fig.11 As shown, an emergency passage is dug obliquely between the transfer passage 50 and the ground, and emergency doors that are opened in an emergency are set at both ends of the emergency passage. The emergency passage is constructed by drilling and blasting, or by excavation with a dump excavator, or by jacking. The height of the emergency passage is not less than 2 meters, preferably 2.5 meters. Ladders, escalators or elevators are set inside the emergency passage according to construction requirements; the emergency passage is connected to the vertical shaft 11, and the vertical shaft 11 serves as a ventilation passage.

[0044] During the construction of the second-layer tunnel, it is sufficient to continue digging at the position of the shaft 11, and then repeat steps S3, S4 and S5 to complete the construction of the second-layer tunnel. During this process, the emergency passage will not be affected. The emergency passage of the second-layer tunnel is excavated obliquely and connected to the upper emergency passage, and a Z-shaped emergency passage can be excavated.

[0045] This application is applied to the construction of urban subways, but is not limited to the construction of urban subways.

[0046] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for constructing an urban subway by first constructing a liaison tunnel and then a shield tunnel, characterized by: The steps include: Step S1, determining the location, depth and size information of the excavation of the communication channel (30); Step S2, before the main tunnel (20) is excavated, the vertical shaft (11) is secretly excavated to a predetermined depth of the communication passage (30), and the vertical shaft support (12) is applied; Step S3, excavating a horizontal communication channel (30) and completing initial support (14) during the excavation process; Step S4, the shield machine constructs the main tunnel (20) and performs temporary tunnel support (21); Step S5, constructing the lining (22) of the communication channel (30) to reinforce the communication channel (30); Through the above steps, the construction of the communication channel (30) is quickly completed.

2. According to claim 1, a method for constructing a city subway by first constructing a communication channel and then a shield tunnel, characterized in that: The initial support (14) includes mortar anchor rods, grouting anchor rods and steel support (13). When the lining (22) of the communication channel (30) is constructed, the steel support (13) is removed.

3. According to the method of claim 1, the construction method of urban subway is characterized by: Step S3 also includes: Step S31, in the shield area of ​​the main tunnel (20) at the end of the communication channel (30), the bell mouth (17) is expanded and supported; Step S32, constructing a temporary safety door (16) between the bell mouth (17) and the communication passage (30); Step S33, removing the support of the bell mouth (17), and filling the position of the bell mouth (17) with lightweight foam concrete (18); After step S4 is completed, the shield segments close to the safety door (16) are removed, and then the safety door (16) and the temporary support (22) are removed, and finally the secondary lining (22) is constructed for reinforcement.

4. According to claim 1, the urban subway construction method of first connecting the channel and then shielding the main tunnel is characterized by: During the construction process, a wellhead transport machine (15) is arranged above the vertical shaft (11) for the entry and exit of construction materials and machinery and the removal of excavated waste; A construction elevator is provided in the vertical shaft (11) for construction workers to enter and exit.

5. According to claim 1, the urban subway construction method of first connecting the channel and then shielding the main tunnel is characterized by: During the shield tunneling of the main tunnel (20), the required materials are delivered through the nearest communication passage (30) and the vertical shaft (11), and construction workers can also enter and exit through the nearest communication passage (30) and the vertical shaft (11); The shield construction of the main tunnel (20) and the connecting channel (30) differ by 1-2 construction periods, that is, the connecting channels (30) are constructed in sequence according to the route, and the shield construction of the main tunnel (20) starts after the construction of the first connecting channel (30) is completed.

6. According to claim 1, the urban subway construction method of first connecting the channel and then shielding the main tunnel is characterized by: The position of the underground excavation shaft (11) is laterally offset at a predetermined position, and after excavating to a sufficient depth, a transfer channel (50) is excavated horizontally to a predetermined position of the communication channel (30), and then the underground excavation of the communication channel (30) is continued horizontally; After the construction is completed, a prefabricated emergency passage connecting the transfer passage (50) and the ground is set up in the shaft (11) as needed, and emergency doors that can be opened in an emergency are set at both ends of the prefabricated emergency passage; A protective door is provided at the connection between the transfer channel (50) and the communication channel (30); A storage room is dug inside the transfer channel (50) for storing emergency rescue tools and construction materials.

7. According to claim 1, the urban subway construction method of first connecting the channel and then shielding the main tunnel is characterized by: Continue digging at the position of the vertical shaft (11) to reach the excavation position of the second-layer main tunnel (20), apply the vertical shaft support (12), and then repeat steps S3, S4 and S5 to complete the construction of the second-layer tunnel. The construction of the second-layer tunnel does not affect the tunnel that has been completed.

8. The urban subway construction method according to claim 7, wherein the first connecting channel and then the shield main tunnel are constructed, characterized in that: An emergency passage is excavated obliquely between the transfer passage (50) and the ground, and emergency doors are provided at both ends of the emergency passage to be opened in an emergency; The emergency passage is connected to the vertical shaft (11), and the vertical shaft (11) serves as a ventilation passage.

9. The urban subway construction method according to claim 6, wherein the connecting channel is first constructed and then the shield main tunnel is constructed, characterized in that: After the construction is completed, it also includes the steps of setting up prefabricated emergency passages: Step S61, according to the depth of the shaft (11), a plurality of pipes (1) are lowered using a crane, a ladder is provided inside the pipes (1), and the ladders in the pipes (1) adjacent to each other are connected; Step S62, a first door opening (201) is opened at the junction of the tube (1) and the transfer channel (50); Step S63, covering the top of the uppermost tube (1) with a tube cover (2), the tube cover (2) being at least 3 meters above the ground, and backfilling the shaft (11) with the tube cover (2); Step S64, digging a safety passage from the ground side to the bottom of the pipe cover (2), opening a second door hole (202) at the connection between the pipe cover (2) and the safety passage, and the second door hole (202) is connected to the ladder; Step S65, constructing emergency doors at the first door opening (201) and the second door opening (202); A first door hole (101) is provided on the side of the tube (1) connected to the communication channel (30), a second door hole (201) is provided on the side of the tube cover (2), a staircase (3) is provided on the inner wall of the tube (1) in a spiral shape, a platform (4) is provided at the top of the staircase (3) in the same tube (1), a railing (5) is provided at one end of the staircase (3) and the platform (4) away from the inner wall of the tube (1), between two adjacent tubes (1), the platform (4) is connected to the staircase (3), the first door hole (101) is connected to the staircase (3), and the second door hole (201) is connected to the platform (4); A plug-in tube (6) is fixed to the bottom end of the inner wall of the tube (1) and the tube cover (2), and the plug-in tube (6) is inserted into the tube (1) below; The top of the inner wall of the tube (1) and the top of the tube cover (2) are both fixed with connecting rings (7) for lifting; The outer side walls of the tube (1) and the tube cover (2) are both provided with an anti-corrosion coating.

10. The urban subway construction method of claim 9, wherein the method comprises: Continue digging at the position of the vertical shaft (11) to reach the excavation position of the second-layer main tunnel (20), and then repeat steps S3, S4 and S5 to complete the construction of the second-layer tunnel; When constructing the second-level tunnel, if the construction is carried out at the same time as the first-level tunnel, the emergency passage is constructed after the communication passage (30) and the main tunnel (20) at the same shaft (11) are completed. If a second-layer passage is to be added later, the backfill on the pipe cover (2) can be excavated, and then the pipe cover (2) and the pipe tube (1) can be lifted one by one, and then the second-layer excavation construction can be continued. After completion, the emergency passage can be reconstructed.

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