Shield construction method for large-gradient small-radius curve subway tunnel in complex environment

Abstract

The invention relates to the technical field of subway tunnel construction, and discloses a shield construction method for a large-gradient small-radius curve subway tunnel in a complex environment, which comprises the following steps: S1, selecting a model of a shield tunneling machine; s2, duct piece type selection; s3, pre-deviating a shield propulsion axis; s4, splicing point location selection; s5, controlling the attitude of the shield tunneling machine; s6, synchronous grouting is conducted; s7, anti-sliding measures are taken; and S8, quality control of the formed tunnel. According to the shield construction method for the large-gradient small-radius curve subway tunnel in the complex environment, through reasonable shield machine model selection, the shield machine can meet the construction requirements of small-radius turning and large-gradient climbing, the adaptability and posture control capacity of the shield machine under the complex working condition are improved, the construction risk and tunnel forming deviation are reduced, and the construction efficiency is improved. Through the scientific duct piece type selection and splicing mode, the integrality and stability of the tunnel lining are enhanced, the waterproof performance of the tunnel is improved, the service life of the tunnel is prolonged, and the safety of the tunnel is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of subway tunnel construction, in particular to a shield construction method for a subway tunnel with a large slope and small radius curve under a complex environment. Background Art

[0002] With urban development, subway construction has become a crucial tool for addressing traffic congestion. Due to constraints such as existing urban buildings, underground pipelines, and topography, subway line planning inevitably introduces steep, small-radius curved tunnels. The construction of these steep, small-radius curved subway tunnels presents numerous challenges, and traditional shield tunneling methods have limitations in addressing these complex conditions.

[0003] When it comes to shield machine selection, conventional shield machine design parameters are difficult to meet the requirements of tight turns and steep slopes. This can lead to difficulty controlling the machine's posture during tunneling, increasing construction risks and the possibility of tunnel formation deviation. When selecting segments, failure to properly select segment type and assembly method based on curve radius and slope can compromise the integrity and stability of the tunnel lining, ultimately impacting the tunnel's service life and safety. Controlling the shield's propulsion axis is particularly challenging in steep, small-radius curves. Without proper pre-deflection settings, tunnel axis deviation may exceed regulatory limits, posing a risk to subsequent track laying and operation. Improper assembly point selection can lead to an unreasonable gap between the segments and the shield shell, compromising segment assembly quality and the tunnel's waterproofing performance. Synchronous grouting is a critical process for ensuring soil stability around the tunnel and controlling ground subsidence. Grouting effectiveness in complex curved sections directly impacts tunnel formation quality and the safety of the surrounding environment. Improper control of grouting pressure, volume, and slurry properties can easily lead to excessive ground subsidence, segment buoyancy, or lateral movement. In addition, under conditions of large slopes, electric vehicles in horizontal transportation systems are prone to slipping. Traditional electric vehicle braking systems and power supply methods are difficult to meet the requirements of large-slope transportation, posing a serious threat to construction safety.

[0004] In summary, it is necessary to design a shield construction method for subway tunnels with large slopes and small radius curves in complex environments to solve the above problems. Summary of the Invention

[0005] The present invention provides the following technical solution: a shield construction method for a subway tunnel with a large slope and small radius curve in a complex environment, comprising the following steps: S1. Shield machine selection A composite earth pressure balance shield machine (EPB) was selected, with an excavation diameter of 6830mm and a total length of 9m. It was designed to meet the requirements of a minimum turning radius of 300m and a gradeability of 35‰. The shield machine was equipped with a passive articulation device, with a maximum travel difference of 150mm and a maximum turning angle of 1.4°. There were 14 of these devices. S2. Segment Selection According to the tunnel line design, universal wedge-shaped segments with a ring width of 1.2m are used in the transition curve and circular curve range, and universal wedge-shaped segments with a ring width of 1.5m are used in other sections. The wedge of the segments is 39.6mm. The lining ring consists of one capping segment K, two adjacent segments B1 and B2, and three standard segments A, and is assembled using a staggered joint method. S3, shield propulsion axis pre-deflection During tunneling of small radius curves, a pre-deflection of 20 to 30 mm is set and dynamically adjusted based on the ground conditions in the tunneling area and tunnel deviation monitoring results. S4. Assembly point selection The segments are assembled using staggered joints, with 16 assembly points. The optimal points are selected by adjusting the wedge shape of the segments to fit the turns of the tunnel line. S5, Shield Machine Attitude Control The shield axis deviation from the design axis is controlled within ±30mm. A fully automatic measurement control system and manual measurement verification are used. The deviation correction amount does not exceed 5mm / ring. The posture adjustment is achieved by operating the propulsion cylinder in different zones. S6, synchronous grouting Increase the strength of the synchronous grouting slurry in the curved section, control the grouting pressure at 3-4.5 bar, and calculate the grouting volume based on the excavation diameter and the outer diameter of the segment, implementing a "quantity and pressure dual control" system; S7. Anti-slip measures The horizontal transport system uses a lithium battery-powered electric vehicle with a traction force of 55T. The front of the electric vehicle is equipped with an emergency brake hook, which is controlled by air brakes. In the event of slipping, the anchor hook is activated to force the vehicle to stop. S8, quality control of formed tunnels Through parameter summary and dynamic adjustment, the tunnel axis and lining ring posture are ensured to meet the design and specification requirements.

[0006] Preferably, in step S1, the shield machine main body consists of a cutterhead, a front shield, a middle shield, a shield tail, a segment assembler and a screw conveyor, and the rear supporting system consists of a connecting bridge, a trolley and a segment crane system. The cutterhead is a spoke plus panel structure with an opening rate of 40%.

[0007] Preferably, in step S2, the inner diameter of the pipe segment is 5900 mm, the outer diameter is 6600 mm, the thickness is 350 mm, C50 reinforced concrete is used, and the water resistance grade is P12.

[0008] Preferably, in step S3, the setting of the pre-deviation amount is based on theoretical calculations and construction practice experience, and is dynamically adjusted in combination with the formation conditions, and the pre-deviation range is 20 to 30 mm.

[0009] Preferably, in step S4, the theoretical shield tail installation gap of the pipe segment is 65 mm at the front end and 30 mm at the shield tail brush step, and the optimal point among the 14 assembly points is selected by adjusting the wedge amount.

[0010] Preferably, in step S5, three methods of rolling correction, vertical correction and horizontal correction are adopted, the correction amount does not exceed 5 mm / ring, and the shield posture is monitored in real time through the guidance system.

[0011] Preferably, in step S6, the slurry ratio is 165 kg of cement, 300 kg of fly ash, 30 kg of bentonite, 825 kg of sand, and 320 kg of water. The slurry gelling time is 3 to 6 hours, and the strength of the consolidated body is not less than 0.2 MPa in 1 day and not less than 3 MPa in 28 days.

[0012] Preferably, in step S7, the upgrade and transformation of the electric vehicle's brake system includes increasing the traction to 55T, using lithium batteries for power supply, and providing an emergency brake anchor hook, which is controlled by air brakes to force the vehicle to stop when it slips.

[0013] Preferably, in step S8, by adopting 1.2m width segments, axis pre-deviation, frequent correction and slow correction posture control and synchronous grouting reinforcement measures, it is ensured that the formed tunnel has no misalignment, cracking and water leakage, and the tunnel axis deviation is controlled within the allowable range of the specification.

[0014] Compared with the existing technology, the present invention provides a shield construction method for subway tunnels with large slopes and small radius curves under complex environments, which has the following beneficial effects: The shield construction method for subway tunnels with large slopes and small radius curves in this complex environment, through reasonable shield machine selection, enables the shield machine to meet the construction requirements of small radius turns and large slope climbing, improves the adaptability and attitude control ability of the shield machine under complex working conditions, reduces construction risks and tunnel forming deviations, and enhances the integrity and stability of the tunnel lining through scientific segment selection and assembly methods, improves the tunnel's waterproof performance and service life, and ensures the safety of the tunnel.

[0015] The shield construction method for subway tunnels with large slopes and small radius curves in this complex environment effectively controls the tunnel axis deviation through the shield propulsion axis pre-deviation and dynamic adjustment mechanism, ensures the tunnel forming quality, and provides a good foundation for subsequent track laying and operation. The precise assembly point selection method ensures the rationality of the gap between the segments and the shield shell, improves the segment assembly quality, and reduces the risk of segment misalignment and leakage. The optimization measures for synchronous grouting, including slurry ratio optimization, performance index control, and precise control of grouting pressure and grouting volume, improve the grouting effect, effectively control ground subsidence and segment floating and lateral displacement, and protect the safety of the surrounding environment.

[0016] The shield construction method for subway tunnels with large slopes and small radius curves in this complex environment and the implementation of anti-slip measures have improved the safety and reliability of the horizontal transportation system, avoided the occurrence of battery vehicle slippage accidents, and ensured the safety of construction workers and the normal operation of construction equipment. The full preparation before construction, real-time monitoring of the construction process, quality control of pipe segment assembly, and maintenance of construction equipment and environment have formed a complete construction quality assurance system, ensuring the safety and efficiency of the entire construction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the process structure of the present invention; Figure 2 This is a structural diagram of a 1.5-meter segment of the present invention; Figure 3 This is a structural diagram of a 1.2-meter segment of the present invention; Figure 4 A structural diagram for selecting the assembly points of the pipe segments of the present invention; Figure 5 This is a schematic diagram of the structure of the forming tunnel of the present invention. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments 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.

[0019] See also Figure 1-5 The present invention provides a technical solution: a shield construction method for a subway tunnel with a large slope and small radius curve under a complex environment, comprising the following steps: S1. Shield machine selection A composite earth pressure balance shield machine (EPB) was selected, with an excavation diameter of 6830mm and a total length of 9m. It was designed to meet the requirements of a minimum turning radius of 300m and a gradeability of 35‰. The shield machine was equipped with a passive articulation device, with a maximum travel difference of 150mm and a maximum turning angle of 1.4°. There were 14 of these devices. S2. Segment Selection According to the tunnel line design, universal wedge-shaped segments with a ring width of 1.2m are used in the transition curve and circular curve range, and universal wedge-shaped segments with a ring width of 1.5m are used in other sections. The wedge of the segments is 39.6mm. The lining ring consists of one capping segment K, two adjacent segments B1 and B2, and three standard segments A, and is assembled using a staggered joint method. S3, shield propulsion axis pre-deflection During tunneling of small radius curves, a pre-deflection of 20 to 30 mm is set and dynamically adjusted based on the ground conditions in the tunneling area and tunnel deviation monitoring results. S4. Assembly point selection The segments are assembled using staggered joints, with 16 assembly points. The optimal points are selected by adjusting the wedge shape of the segments to fit the turns of the tunnel line. S5, Shield Machine Attitude Control The shield axis deviation from the design axis is controlled within ±30mm. A fully automatic measurement control system and manual measurement verification are used. The deviation correction amount does not exceed 5mm / ring. The posture adjustment is achieved by operating the propulsion cylinder in different zones. S6, synchronous grouting Increase the strength of the synchronous grouting slurry in the curved section, control the grouting pressure at 3-4.5 bar, and calculate the grouting volume based on the excavation diameter and the outer diameter of the segment, implementing a "quantity and pressure dual control" system; S7. Anti-slip measures The horizontal transport system uses a lithium battery-powered electric vehicle with a traction force of 55T. The front of the electric vehicle is equipped with an emergency brake hook, which is controlled by air brakes. In the event of slipping, the anchor hook is activated to force the vehicle to stop. S8, quality control of formed tunnels Through parameter summary and dynamic adjustment, the tunnel axis and lining ring posture are ensured to meet the design and specification requirements.

[0020] Furthermore, in step S1, the shield machine main body consists of a cutterhead, a front shield, a middle shield, a shield tail, a segment assembly machine and a screw conveyor, and the rear supporting system consists of a connecting bridge, a trolley and a segment crane system. The cutterhead is a spoke plus panel structure with an opening rate of 40%.

[0021] Furthermore, in step S2, the inner diameter of the pipe segment is 5900 mm, the outer diameter is 6600 mm, the thickness is 350 mm, C50 reinforced concrete is used, and the water resistance grade is P12.

[0022] Furthermore, in step S3, the pre-deviation amount is set based on theoretical calculations and construction practice experience, and is dynamically adjusted in combination with the formation conditions, with the pre-deviation range being 20 to 30 mm.

[0023] Furthermore, in step S4, the theoretical installation gap between the segment and the shield tail is 65 mm at the front end and 30 mm at the brush step of the shield tail. The optimal position among the 14 possible assembly points is selected by adjusting the wedge amount.

[0024] Furthermore, in step S5, three methods of rolling correction, vertical correction and horizontal correction are adopted, the correction amount does not exceed 5mm / ring, and the shield posture is monitored in real time through the guidance system.

[0025] Furthermore, in step S6, the slurry ratio is 165 kg of cement, 300 kg of fly ash, 30 kg of bentonite, 825 kg of sand, and 320 kg of water. The slurry gelling time is 3 to 6 hours, and the strength of the consolidated body is not less than 0.2 MPa in 1 day and not less than 3 MPa in 28 days.

[0026] Furthermore, in step S7, the upgrade and transformation of the electric vehicle's brake system includes increasing the traction to 55T, using lithium batteries for power supply, and setting an emergency brake anchor hook, which is controlled by air brakes to force the vehicle to stop when it slips.

[0027] Furthermore, in step S8, by adopting 1.2m wide segments, axis pre-deviation, frequent and slow correction posture control and synchronous grouting reinforcement measures, it is ensured that the formed tunnel has no misalignment, cracking and water leakage, and the tunnel axis deviation is controlled within the allowable range of the specification.

[0028] This shield construction method for a subway tunnel with a steep, small-radius curve in a complex environment utilizes appropriate shield machine selection, enabling it to meet the construction requirements of small-radius turns and steep climbs. This improves the shield machine's adaptability and attitude control capabilities under complex working conditions, reducing construction risks and tunnel formation deviations. Scientific segment selection and assembly methods enhance the integrity and stability of the tunnel lining, improve the tunnel's waterproofing performance and service life, and ensure tunnel safety. Precise pre-deflection and dynamic adjustment of the shield's propulsion axis effectively control tunnel axis deviation, ensuring tunnel formation quality and laying a solid foundation for subsequent track laying and operation. Precise assembly point selection ensures a reasonable gap between the segments and the shield shell, improving segment assembly quality and reducing the risk of segment misalignment and leakage. Optimized synchronous grouting measures, including slurry ratio optimization, performance index control, and precise control of grouting pressure and injection volume, enhance grouting effectiveness, effectively control ground subsidence, segment uplift, and lateral movement, and protect the surrounding environment. The implementation of anti-skidding measures has improved the safety and reliability of the horizontal transportation system, avoided the occurrence of electric vehicle skidding accidents, and ensured the safety of construction workers and the normal operation of construction equipment. The full preparation before construction, real-time monitoring of the construction process, quality control of pipe segment assembly, and maintenance of construction equipment and environment have formed a complete construction quality assurance system to ensure the safety and efficiency of the entire construction process.

[0029] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A shield construction method for a subway tunnel with a large slope and small radius curve in a complex environment, characterized by: The following steps are involved: S1. Shield machine selection A composite earth pressure balance shield machine (EPB) was selected, with an excavation diameter of 6830mm and a total length of 9m. It was designed to meet the requirements of a minimum turning radius of 300m and a gradeability of 35‰. The shield machine was equipped with a passive articulation device, with a maximum travel difference of 150mm and a maximum turning angle of 1.4°. There were 14 of these devices. S2. Segment Selection According to the tunnel line design, universal wedge-shaped segments with a ring width of 1.2m are used in the transition curve and circular curve range, and universal wedge-shaped segments with a ring width of 1.5m are used in other sections. The wedge of the segments is 39.6mm. The lining ring consists of one capping segment K, two adjacent segments B1 and B2, and three standard segments A, and is assembled using a staggered joint method. S3, shield propulsion axis pre-deflection During tunneling of small radius curves, a pre-deflection of 20 to 30 mm is set and dynamically adjusted based on the ground conditions in the tunneling area and tunnel deviation monitoring results. S4. Assembly point selection The segments are assembled using staggered joints, with 16 assembly points. The optimal points are selected by adjusting the wedge shape of the segments to fit the turns of the tunnel line. S5, Shield Machine Attitude Control The shield axis deviation from the design axis is controlled within ±30mm. A fully automatic measurement control system and manual measurement verification are used. The deviation correction amount does not exceed 5mm / ring. The posture adjustment is achieved by operating the propulsion cylinder in different zones. S6, synchronous grouting Increase the strength of the synchronous grouting slurry in the curved section, control the grouting pressure at 3-4.5 bar, and calculate the grouting volume based on the excavation diameter and the outer diameter of the segment, implementing a "quantity and pressure dual control" system; S7. Anti-slip measures The horizontal transport system uses a lithium battery-powered electric vehicle with a traction force of 55T. The front of the electric vehicle is equipped with an emergency brake hook, which is controlled by air brakes. In the event of slipping, the anchor hook is activated to force the vehicle to stop. S8, quality control of formed tunnels Through parameter summary and dynamic adjustment, the tunnel axis and lining ring posture are ensured to meet the design and specification requirements.

2. The shield construction method for a subway tunnel with a large slope and small radius curve under a complex environment according to claim 1 is characterized in that: In step S1, the shield machine main body consists of a cutterhead, a front shield, a middle shield, a shield tail, a segment assembler and a screw conveyor, and the rear supporting system consists of a connecting bridge, a trolley and a segment crane system. The cutterhead is a spoke plus panel structure with an opening rate of 40%.

3. The shield construction method for a subway tunnel with a large slope and small radius curve under a complex environment according to claim 1 is characterized in that: In step S2, the inner diameter of the pipe segment is 5900 mm, the outer diameter is 6600 mm, the thickness is 350 mm, C50 reinforced concrete is used, and the water resistance grade is P12.

4. The shield construction method for a subway tunnel with a large slope and small radius curve under a complex environment according to claim 1 is characterized in that: In step S3, the pre-deviation amount is set based on theoretical calculations and construction practice experience, and is dynamically adjusted in combination with stratum conditions. The pre-deviation range is 20 to 30 mm.

5. The shield construction method for a subway tunnel with a large slope and small radius curve under a complex environment according to claim 1 is characterized in that: In step S4, the theoretical shield tail installation gap of the segment is 65 mm at the front end and 30 mm at the shield tail brush step, and the optimal point among the 14 possible assembly points is selected by adjusting the wedge amount.

6. The shield construction method for a subway tunnel with a large slope and small radius curve under a complex environment according to claim 1 is characterized in that: In step S5, three methods of rolling correction, vertical correction and horizontal correction are adopted, the correction amount does not exceed 5mm / ring, and the shield posture is monitored in real time through the guidance system.

7. The shield construction method for a subway tunnel with a large slope and small radius curve under a complex environment according to claim 1 is characterized in that: In step S6, the slurry ratio is 165 kg of cement, 300 kg of fly ash, 30 kg of bentonite, 825 kg of sand, and 320 kg of water. The slurry gelation time is 3 to 6 hours, and the strength of the consolidated body is not less than 0.2 MPa in one day and not less than 3 MPa in 28 days.

8. The shield construction method for a subway tunnel with a large slope and small radius curve under a complex environment according to claim 1 is characterized in that: In step S7, the upgrade and transformation of the electric vehicle's brake system includes increasing the traction to 55T, using lithium batteries for power supply, and setting an emergency brake anchor hook, which is controlled by air brakes to force the vehicle to stop when it slips.

9. The shield construction method for a subway tunnel with a large slope and small radius curve under a complex environment according to claim 1 is characterized in that: In step S8, by adopting 1.2m wide segments, axis pre-deviation, frequent and slow correction posture control and synchronous grouting reinforcement measures, it is ensured that the formed tunnel has no misalignment, cracking and water leakage, and the tunnel axis deviation is controlled within the allowable range of the specification.

Images