Construction method for subway shield receiving of special-shaped station in urban sensitive area

Abstract

The invention relates to the technical field of urban sensitive area shield receiving construction, and discloses a construction method for special-shaped station subway shield receiving in an urban sensitive area, which comprises the following steps: S1, early-stage preparation of a hole: arranging a detailed foundation pit near the hole, and fully considering the geological characteristics of the urban sensitive area and the influence of surrounding buildings, the specific range of a shield receiving area is determined; s2, arrangement of steel sleeves: a series of reasonably distributed steel sleeves are arranged in the receiving area by using an accurate measuring and positioning technology, the diameter and depth of the steel sleeves are determined according to factors such as stratum characteristics and shield diameter, and the whole receiving area is ensured to be covered. The steel sleeve freezing method for receiving can reduce the receiving risk of the shield in the urban sensitive area, the blocking and grouting back pressure of the shield in the receiving stage is larger, secondary grouting filling is more compact, and the problem of ground surface settlement can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of shield receiving construction devices in urban sensitive areas, and in particular to a construction method for receiving subway shields at special-shaped stations in urban sensitive areas. Background Art

[0002] In the process of urbanization, subway transportation system has been widely used as an efficient and convenient public transportation mode. However, in sensitive urban areas, such as historical and cultural protection areas, ecologically sensitive areas, and prosperous commercial areas, subway shield construction is often subject to many restrictions and challenges. The traditional subway shield construction method has a series of technical difficulties and social contradictions in solving these problems. At present, the subway shield construction method adopts the freezing method. However, the original freezing method may have water seepage channels during the active freezing period, resulting in the failure of the freezing curtain; in the maintenance freezing stage, since the inner ring freezing pipes have been pulled out, after removing the thickness of the enclosure structure, the thickness of the frozen body on the front of the tunnel will only be about 1.8m. There may be risks in the process from the tunnel door to the shield safe entry and exit; because the frozen wall directly above and below the tunnel is basically not supplied with cold during the maintenance freezing, and the width is large, it is easy to cause the frozen wall directly below the tunnel to melt too quickly, resulting in the risk of water and sand gushing. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a construction method for receiving subway shields at special-shaped stations in sensitive urban areas, which solves the problem that the freezing method used in the prior art causes the frozen wall directly below the tunnel to melt too quickly, resulting in the risk of water and sand gushing.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions: A construction method for receiving a subway shield at a special-shaped station in a sensitive urban area, comprising the following steps: S1. Preliminary preparation for the tunnel entrance: set up a detailed foundation pit near the tunnel entrance, fully consider the geological characteristics of the sensitive urban area and the impact of surrounding buildings, and determine the specific scope of the shield receiving area; S2. Setting of steel sleeves: Using precise measurement and positioning technology, a series of reasonably distributed steel sleeves are set in the receiving area. The diameter and depth of the steel sleeves are determined according to factors such as stratum characteristics and shield diameter to ensure that the entire receiving area is covered; S3. Injection of freezing liquid and formation of freezing curtain: Inject freezing liquid with high cooling performance into the steel sleeve to form a solid freezing curtain through circulation to resist the formation of seepage channels and reduce the ground temperature during active freezing; S4. Maintaining the frozen state: By scientifically controlling the temperature and flow rate of the freezing liquid, the frozen state is maintained, the integrity of the freezing curtain is maintained, and the risk of water leakage is reduced; S5. Management of shield excavation process: Shield excavation is carried out in the area surrounded by the freezing curtain to ensure that the shield avoids encountering unfrozen or insufficiently frozen strata during the receiving process, and a control system is used to ensure the safety and accuracy of the construction; S6, freezing pipe extraction and backfilling process: After the shield completes the reception, the freezing pipes are gradually extracted and backfilled in the freezing curtain to ensure that the thickness of the frozen body on the front of the tunnel is maintained within a safe range to prevent potential risks caused by the reduction of the frozen body; S7, grouting reinforcement: carry out efficient grouting in the steel sleeve, increase the back pressure of the plugging grouting, and ensure that the secondary grouting filling is more dense to further reduce the risk of surface settlement; S8. Foundation pit removal: After receiving the shield, carefully remove the foundation pit and take appropriate support measures to ensure the safety and stability of the surrounding environment during the construction process.

[0005] Preferably, the step S1 specifically includes the following steps: S101. Conduct detailed geological exploration, including investigations on groundwater conditions, soil structure, underground pipelines, etc. This will help understand the geological characteristics and determine whether there are special geological conditions, such as soft soil, rock formations, groundwater levels, etc., and their possible impact on shield construction; S102. Investigate the structural characteristics and foundation conditions of surrounding buildings, and assess the possible impact of shield construction on these buildings and structures to determine safety distances and protective measures; S103. Evaluate the surrounding environment, residents, traffic and other factors, consider the possible impact of construction on urban life and traffic, and formulate corresponding construction plans and safety measures; S104. Based on the aforementioned survey data and analysis results, use engineering simulation software or technology to plan the challenges and problems that may be encountered during shield construction and design a reasonable construction path and area scope; S105. Comply with relevant regulations and standards, follow urban planning, building regulations and relevant standards, ensure that the construction process complies with legal and regulatory requirements, and ensure safety and environmental protection in sensitive urban areas.

[0006] Preferably, the step S2 specifically includes the following steps: S201. Determine the diameter of the steel sleeve to be set according to the specific shield machine model and diameter. The shield diameter is determined by the engineering design, and the sleeve diameter should be slightly larger than the shield diameter to accommodate the movement of the shield machine and uncertain factors during the construction process. S202, using precise measurement and positioning technology, such as a total station, a laser rangefinder, etc., to measure the receiving area, including determining the coordinates, depth, inclination, and other information of the center of the sleeve; S203. Based on the geological data and measurement results, design a reasonable sleeve layout plan, determine the spacing and distribution map between the sleeves, and ensure that the entire receiving area is fully covered; S204. After the survey and design are completed, preparatory work before construction is carried out, including cleaning the work area, purchasing the required steel sleeve materials and equipment, to ensure the smooth progress of the construction process; S205. Use professional equipment and tools to install the steel sleeves one by one to the designated positions. During the installation process, ensure the verticality and horizontality of the sleeves to ensure the accuracy of subsequent shield construction; S206. After the sleeve is installed, quality control and inspection are carried out, including checking the position, depth, inclination and other parameters of the sleeve to ensure that they meet the design requirements.

[0007] Preferably, the step S3 specifically includes the following steps: S301. Design the size, depth, density and other parameters of the freezing curtain according to geological exploration data and engineering requirements, taking into account the formation permeability and environmental conditions, and determining the type and performance of the cooling liquid; S302. Before the actual construction, a preliminary test is conducted to verify the diffusion and freezing effect of the freezing liquid in the formation, which is helpful to adjust the proportion and injection speed of the freezing liquid; S303, clean and prepare the inside of the steel sleeve to ensure that the surface is smooth and clean, and there are no impurities that affect the injection of the freezing liquid and the cooling effect; S304, using special equipment, injecting a freezing liquid into the steel sleeve through a pipeline, wherein the liquid is a mixture of efficient cooling, such as brine, ethylene glycol, etc., wherein the injection process needs to control the speed and pressure to ensure uniform filling and prevent leakage; S305. After injection, the circulation system is started to ensure that the freezing liquid flows evenly in the steel sleeve to promote heat transfer and accelerate formation freezing; S306. During the injection and cooling process, the temperature, flow rate and other parameters are continuously monitored, and the injection speed and the cooling liquid ratio are adjusted in time according to the monitoring results to ensure that the freezing effect reaches the expected value; S307. As time goes by, the freezing liquid gradually cools in the formation to form a solid freezing curtain, wherein this process takes weeks or even months, and the specific time depends on the characteristics of the formation and the performance of the cooling liquid; S308. After the freezing curtain is formed, stability monitoring is performed to ensure the firmness and durability of the freezing curtain to prevent the formation of water seepage channels.

[0008] Preferably, the step S5 specifically includes the following steps: S501. Before excavation, conduct detailed geological survey to understand the nature of the stratum, including geological structure, soil characteristics, hydrogeological conditions, etc., to ensure that the coverage of the freezing curtain matches the actual situation of the stratum; S502. During shield excavation, the temperature and integrity of the freezing curtain are continuously monitored, which helps to ensure the effectiveness of the freezing curtain and prevent unfrozen or insufficiently frozen strata from being encountered. Real-time monitoring of temperature and curtain integrity can be achieved through sensors and monitoring systems. S503, using an advanced control system to precisely control the freezing curtain, including controlling the temperature, flow rate and flow direction of the cooling liquid to ensure that the freezing curtain remains stable throughout the construction process; S504. Build numerical models and simulations to predict the performance and impact of freezing curtains, which can help engineering teams better understand the freezing process, predict possible ground reactions, and make timely adjustments in actual construction; S505. During the shield excavation process, a real-time monitoring system is used to monitor the position, posture, vibration and other parameters of the shield, which helps to detect any abnormal situation in time and take necessary measures to ensure the safety of construction; S506. Develop a detailed emergency response plan, including plans for possible ground conditions, to ensure that the team has the ability to handle unexpected situations, including unfrozen or insufficiently frozen ground conditions.

[0009] Preferably, the step S6 specifically includes the following steps: S601. Before the freezing pipe is pulled out and backfilled, the temperature distribution and thickness of the frozen body shall be carefully measured and recorded through the monitoring system. This can be achieved by installing temperature and thickness sensors in the frozen body to ensure that the frozen body in the area in front of the tunnel portal is maintained within a safe range. S602, gradually pulling out the frozen pipes, usually in sections, to ensure the stability of the frozen body, wherein the speed and sequence of pulling out the pipes may need to be adjusted according to the actual freezing situation and engineering requirements, and while pulling out the pipes, monitor the changes of the frozen body to ensure that no abnormal situation occurs; S603. The material prepared for backfill is a material that can provide support and fill voids, wherein the backfill material includes concrete, expansive soil or similar supporting materials. Ensure that the backfill material meets the engineering requirements and can provide sufficient support and stability; S604, injecting backfill material into the frozen body by grouting or other appropriate methods to ensure that each part is filled and any gaps that may exist are filled. During the backfilling process, the temperature and thickness of the frozen body are continuously monitored to ensure that the frozen body on the front of the tunnel portal is maintained within a safe range; S605. Adjust the operation during the backfilling process at any time according to the real-time monitoring data, including adjusting the injection speed, position and pressure of the backfilling material to ensure the stability of the frozen body.

[0010] Preferably, the step S7 specifically includes the following steps: S701. Install steel sleeves at locations that require reinforcement. The diameter and length of the sleeves should meet the requirements of the engineering design and be able to accommodate grouting equipment. S702. Arrange grouting pipes inside the sleeve to ensure that they cover the entire reinforcement area. The location and arrangement of the grouting pipes should be determined according to geological exploration and design requirements; S703. After the grouting pipe is arranged, preparation for plugging is carried out, which includes selecting appropriate plugging materials, such as expansive soil, cement slurry, etc.; S704, then grouting is performed, and the grouting pressure is gradually increased so that the plugging material fills the gap around the sleeve. By increasing the grouting back pressure, the plugging effect can be improved to ensure that the plugging material is fully filled into the formation; S705. During the grouting process, the grouting parameters are adjusted in time by real-time monitoring of the grouting pressure, flow rate, stratum deformation and other parameters to ensure the stability and effectiveness of the grouting process; S706. After the initial grouting is completed, secondary grouting is performed to fill more materials and improve the stability of the formation. In the secondary grouting, the grouting pressure also needs to be gradually increased to ensure a denser filling.

[0011] Preferably, the step S7 also includes: when the grouting volume and formation stability required by the design are reached, the grouting process is ended, and the grouting pressure is gradually reduced to ensure that the grouting pipe does not produce backflow. After the grouting is completed, the grouting pipe is cleaned to prevent the material from solidifying and clogging the pipe. Then, the grouting equipment and sleeve can be removed.

[0012] Preferably, the appropriate support measures taken in step S8 include installing and maintaining appropriate support structures, such as support frames, support walls, etc., to prevent soil collapse and collapse.

[0013] The present invention provides a construction method for receiving a subway shield at a special-shaped station in a sensitive urban area. It has the following beneficial effects: 1. Compared with the existing freezing method, the steel sleeve plus freezing method can reduce the risk of shield receiving in sensitive urban areas. After the steel sleeve is installed and backfilled, the risk of water leakage caused by the failure of the freezing curtain during active freezing and maintenance freezing can be effectively reduced. Especially in sensitive urban areas, the control of surface settlement is relatively fine. When steel sleeves are used for receiving, due to the presence of backfill material in the steel sleeve, the shield has a greater back pressure of plugging grouting in the receiving stage, making the secondary grouting filling more compact, which can effectively reduce surface settlement. At the same time, it can also prevent water and sand gushing from the tunnel gate in the receiving stage due to inadequate plugging grouting or the presence of permeable channels, thereby reducing the risk of receiving.

[0014] 2. The present invention adopts a comprehensive construction method combined with advanced shield technology and takes appropriate support measures to ensure the stability of the tunnel and subway structure during construction and subsequent use. This is not only related to the quality of the project itself, but also to the life safety of construction workers and surrounding residents. By implementing regular monitoring and risk assessment, potential problems can be discovered in time and corresponding measures can be taken, thereby reducing adverse effects during the progress of the project. This helps to maintain the controllability and sustainability of the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following will be combined with the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention. Embodiment:

[0016] The embodiment of the present invention provides a construction method for receiving a subway shield machine at a special-shaped station in a sensitive area of ​​a city, comprising the following steps: S1. Preliminary preparation for the tunnel entrance: set up a detailed foundation pit near the tunnel entrance, fully consider the geological characteristics of the sensitive urban area and the impact of surrounding buildings, and determine the specific scope of the shield receiving area; The S1 step specifically includes the following steps: S101. Conduct detailed geological exploration, including investigations on groundwater conditions, soil structure, underground pipelines, etc. This will help understand the geological characteristics and determine whether there are special geological conditions, such as soft soil, rock formations, groundwater levels, etc., and their possible impact on shield construction; Specifically, through these surveys, we can gain a deeper understanding of geological characteristics, determine whether there are special geological conditions such as soft soil and rock formations, and their possible impact on shield construction. In addition, the investigation of groundwater conditions can help us predict possible changes in groundwater levels and develop corresponding response strategies.

[0017] S102. Investigate the structural characteristics and foundation conditions of surrounding buildings, and assess the possible impact of shield construction on these buildings and structures to determine safety distances and protective measures; Specifically, by gaining a deeper understanding of the structural characteristics of these buildings, we can determine the safe distance to stay from them and take necessary protective measures to avoid damage to them during construction.

[0018] S103. Evaluate the surrounding environment, residents, traffic and other factors, consider the possible impact of construction on urban life and traffic, and formulate corresponding construction plans and safety measures; Specifically, this will take into account the possible impact of construction on urban life and transportation, and formulate corresponding construction plans and safety measures to minimize the impact of construction on the surrounding environment and residents and ensure the normal operation of urban life.

[0019] S104. Based on the aforementioned survey data and analysis results, use engineering simulation software or technology to plan the challenges and problems that may be encountered during shield construction and design a reasonable construction path and area scope; Specifically, by simulating the construction process, we can predict the problems that may be encountered and design a reasonable construction path and area scope. This will help us better deal with the problems that may arise during the actual construction process.

[0020] S105. Comply with relevant regulations and standards, follow urban planning, building regulations and relevant standards, ensure that the construction process complies with legal and regulatory requirements, and ensure safety and environmental protection in sensitive urban areas.

[0021] S2. Setting of steel sleeves: Using precise measurement and positioning technology, a series of reasonably distributed steel sleeves are set in the receiving area. The diameter and depth of the steel sleeves are determined according to factors such as stratum characteristics and shield diameter to ensure that the entire receiving area is covered; The S2 step specifically includes the following steps: S201. Determine the diameter of the steel sleeve to be set according to the specific shield machine model and diameter. The shield diameter is determined by the engineering design, and the sleeve diameter should be slightly larger than the shield diameter to accommodate the movement of the shield machine and uncertain factors during the construction process. Specifically, this can ensure that during the construction process, the sleeve can fully protect the shield machine and ensure the smooth progress of the construction.

[0022] S202, using precise measurement and positioning technology, such as a total station, a laser rangefinder, etc., to measure the receiving area, including determining the coordinates, depth, inclination, and other information of the center of the sleeve; Specifically, to ensure that during the installation process, the steel sleeve can be accurately placed in the predetermined position.

[0023] S203. Based on the geological data and measurement results, design a reasonable sleeve layout plan, determine the spacing and distribution map between the sleeves, and ensure that the entire receiving area is fully covered; Specifically, a reasonable layout scheme can improve construction efficiency and ensure that the sleeve can effectively guide the movement of the shield machine during subsequent shield construction.

[0024] S204. After the survey and design are completed, preparatory work before construction is carried out, including cleaning the work area, purchasing the required steel sleeve materials and equipment, to ensure the smooth progress of the construction process; Specifically, these preparations can ensure that the construction process proceeds smoothly and reduce the number of problems that may arise during the construction process.

[0025] S205. Use professional equipment and tools to install the steel sleeves one by one to the designated positions. During the installation process, ensure the verticality and horizontality of the sleeves to ensure the accuracy of subsequent shield construction; Specifically, this requires experienced workers and technicians to operate to ensure the quality and effect of the installation.

[0026] S206. After the sleeve is installed, quality control and inspection are carried out, including checking the position, depth, inclination and other parameters of the sleeve to ensure that they meet the design requirements.

[0027] The S3 step specifically includes the following steps: S301. Design the size, depth, density and other parameters of the freezing curtain according to geological exploration data and engineering requirements, taking into account the formation permeability and environmental conditions, and determining the type and performance of the cooling liquid; S302. Before the actual construction, a preliminary test is conducted to verify the diffusion and freezing effect of the freezing liquid in the formation, which is helpful to adjust the proportion and injection speed of the freezing liquid; S303, clean and prepare the inside of the steel sleeve to ensure that the surface is smooth and clean, and there are no impurities that affect the injection of the freezing liquid and the cooling effect; S304, using special equipment, injecting a freezing liquid into the steel sleeve through a pipeline, wherein the liquid is a mixture of efficient cooling, such as brine, ethylene glycol, etc., wherein the injection process needs to control the speed and pressure to ensure uniform filling and prevent leakage; S305. After injection, the circulation system is started to ensure that the freezing liquid flows evenly in the steel sleeve to promote heat transfer and accelerate formation freezing; S306. During the injection and cooling process, the temperature, flow rate and other parameters are continuously monitored, and the injection speed and the cooling liquid ratio are adjusted in time according to the monitoring results to ensure that the freezing effect reaches the expected value; S307. As time goes by, the freezing liquid gradually cools in the formation to form a solid freezing curtain, wherein this process takes weeks or even months, and the specific time depends on the characteristics of the formation and the performance of the cooling liquid; S308. After the freezing curtain is formed, stability monitoring is performed to ensure the firmness and durability of the freezing curtain to prevent the formation of water seepage channels.

[0028] S4. Maintaining the frozen state: By scientifically controlling the temperature and flow rate of the freezing liquid, the frozen state is maintained, the integrity of the freezing curtain is maintained, and the risk of water leakage is reduced; S5. Management of shield excavation process: Shield excavation is carried out in the area surrounded by the freezing curtain to ensure that the shield avoids encountering unfrozen or insufficiently frozen strata during the receiving process, and a control system is used to ensure the safety and accuracy of the construction; Step S5 specifically includes the following steps: S501. Before excavation, conduct detailed geological survey to understand the nature of the stratum, including geological structure, soil characteristics, hydrogeological conditions, etc., to ensure that the coverage of the freezing curtain matches the actual situation of the stratum; S502. During shield excavation, the temperature and integrity of the freezing curtain are continuously monitored, which helps to ensure the effectiveness of the freezing curtain and prevent unfrozen or insufficiently frozen strata from being encountered. Real-time monitoring of temperature and curtain integrity can be achieved through sensors and monitoring systems. S503, using an advanced control system to precisely control the freezing curtain, including controlling the temperature, flow rate and flow direction of the cooling liquid to ensure that the freezing curtain remains stable throughout the construction process; S504. Build numerical models and simulations to predict the performance and impact of freezing curtains, which can help engineering teams better understand the freezing process, predict possible ground reactions, and make timely adjustments in actual construction; S505. During the shield excavation process, a real-time monitoring system is used to monitor the position, posture, vibration and other parameters of the shield, which helps to detect any abnormal situation in time and take necessary measures to ensure the safety of construction; S506. Develop a detailed emergency response plan, including plans for possible ground conditions, to ensure that the team has the ability to handle unexpected situations, including unfrozen or insufficiently frozen ground conditions.

[0029] S6, freezing pipe extraction and backfilling process: After the shield completes the reception, the freezing pipes are gradually extracted and backfilled in the freezing curtain to ensure that the thickness of the frozen body on the front of the tunnel is maintained within a safe range to prevent potential risks caused by the reduction of the frozen body; The S6 step specifically includes the following steps: S601. Before the freezing pipe is pulled out and backfilled, the temperature distribution and thickness of the frozen body shall be carefully measured and recorded through the monitoring system. This can be achieved by installing temperature and thickness sensors in the frozen body to ensure that the frozen body in the area in front of the tunnel portal is maintained within a safe range. S602, gradually pulling out the frozen pipes, usually in sections, to ensure the stability of the frozen body, wherein the speed and sequence of pulling out the pipes may need to be adjusted according to the actual freezing situation and engineering requirements, and while pulling out the pipes, monitor the changes of the frozen body to ensure that no abnormal situation occurs; S603. The material prepared for backfill is a material that can provide support and fill voids, wherein the backfill material includes concrete, expansive soil or similar supporting materials. Ensure that the backfill material meets the engineering requirements and can provide sufficient support and stability; S604, injecting backfill material into the frozen body by grouting or other appropriate methods to ensure that each part is filled and any gaps that may exist are filled. During the backfilling process, the temperature and thickness of the frozen body are continuously monitored to ensure that the frozen body on the front of the tunnel portal is maintained within a safe range; S605. Adjust the operation during the backfilling process at any time according to the real-time monitoring data, including adjusting the injection speed, position and pressure of the backfilling material to ensure the stability of the frozen body.

[0030] S7, grouting reinforcement: carry out efficient grouting in the steel sleeve, increase the back pressure of the plugging grouting, and ensure that the secondary grouting filling is more dense to further reduce the risk of surface settlement; The S7 step specifically includes the following steps: S701. Install steel sleeves at locations that require reinforcement. The diameter and length of the sleeves should meet the requirements of the engineering design and be able to accommodate grouting equipment. Specifically, in specific locations where foundation reinforcement is required, a steel sleeve needs to be installed. The diameter and length of this steel sleeve must be selected and manufactured in strict accordance with the requirements of the engineering design to ensure that it can accommodate the grouting equipment. At the same time, considering the installation environment and use requirements of the sleeve, it is also necessary to ensure that it can withstand certain pressure and corrosion.

[0031] S702. Arrange grouting pipes inside the sleeve to ensure that they cover the entire reinforcement area. The location and arrangement of the grouting pipes should be determined according to geological exploration and design requirements; Specifically, ensure that they can cover the entire area to be reinforced. At the same time, the location and number of grouting pipes also need to take into account factors such as geological conditions and reinforcement effects to determine the most appropriate layout plan.

[0032] S703. After the grouting pipe is arranged, preparation for plugging is carried out, which includes selecting appropriate plugging materials, such as expansive soil, cement slurry, etc.; Specifically, it includes the selection of appropriate plugging materials. According to the needs of the project, we may choose some plugging materials with special properties, such as expansive soil, cement slurry, etc. These materials need to have excellent plugging effects, and their physical and chemical properties also need to be considered to ensure that they can effectively block the gap around the sleeve.

[0033] S704, then grouting is performed, and the grouting pressure is gradually increased so that the plugging material fills the gap around the sleeve. By increasing the grouting back pressure, the plugging effect can be improved to ensure that the plugging material is fully filled into the formation; Specifically, by increasing the grouting back pressure, we can not only improve the plugging effect, but also ensure that the plugging material can be fully filled into the formation. At the same time, we also need to monitor the grouting pressure, flow rate, and formation deformation in real time, so as to adjust the grouting parameters in time to ensure the stability and effectiveness of the grouting process.

[0034] S705. During the grouting process, the grouting parameters are adjusted in time by real-time monitoring of the grouting pressure, flow rate, stratum deformation and other parameters to ensure the stability and effectiveness of the grouting process; Specifically, these monitoring data can not only be used to adjust the grouting process, but also to evaluate the reinforcement effect so that we can take additional measures to enhance the reinforcement effect when necessary.

[0035] S706. After the initial grouting is completed, the secondary grouting is carried out to fill more materials and improve the stability of the formation. In the secondary grouting, the grouting pressure also needs to be gradually increased to ensure a more compact filling. Among them, step S7 also includes: when the grouting volume and formation stability required by the design are reached, the grouting process is ended, and the grouting pressure is gradually reduced to ensure that the grouting pipe does not produce backflow. After the grouting is completed after this sentence, the grouting pipe is cleaned to prevent the material from solidifying and clogging the pipe. Then, the grouting equipment and sleeve can be removed.

[0036] S8. Foundation pit removal: After receiving the shield, carefully remove the foundation pit and take appropriate support measures to ensure the safety and stability of the surrounding environment during the construction process.

[0037] Appropriate support measures in step S8 include installing and maintaining appropriate support structures, such as support frames, support walls, etc., to prevent soil collapse and collapse.

[0038] In summary: Compared with the existing freezing method, the steel sleeve plus freezing method can reduce the risk of shield receiving in sensitive urban areas. After the steel sleeve is installed and backfilled, it can effectively reduce the risk of water leakage caused by failure of the freezing curtain during active freezing and maintenance freezing. Especially in sensitive urban areas, the control of surface settlement is relatively fine. When using steel sleeve for receiving, due to the presence of backfill material in the steel sleeve, the shield has a greater back pressure of plugging grouting in the receiving stage, making the secondary grouting filling more compact, which can effectively reduce surface settlement. At the same time, it can also prevent water and sand gushing from the tunnel portal in the receiving stage due to inadequate sealing grouting or the existence of permeable channels, thereby reducing the risk of receiving.

[0039] At the same time, a comprehensive construction method should be adopted, combined with advanced shield technology, and appropriate support measures should be taken to ensure the stability of the tunnel and subway structure during construction and subsequent use. This is not only related to the quality of the project itself, but also to the life safety of construction workers and surrounding residents. By implementing regular monitoring and risk assessment, potential problems can be discovered in time and corresponding measures can be taken to reduce the adverse effects of the project progress. This helps to maintain the controllability and sustainability of the project.

[0040] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A construction method for receiving a subway shield at a special-shaped station in a sensitive urban area, characterized in that: The following steps are involved: S1. Preliminary preparation for the tunnel entrance: set up a detailed foundation pit near the tunnel entrance, fully consider the geological characteristics of the sensitive urban area and the impact of surrounding buildings, and determine the specific scope of the shield receiving area; S2. Setting of steel sleeves: Using precise measurement and positioning technology, a series of reasonably distributed steel sleeves are set in the receiving area. The diameter and depth of the steel sleeves are determined according to factors such as stratum characteristics and shield diameter to ensure that the entire receiving area is covered; S3. Injection of freezing liquid and formation of freezing curtain: Inject freezing liquid with high cooling performance into the steel sleeve to form a solid freezing curtain through circulation to resist the formation of seepage channels and reduce the ground temperature during active freezing; S4. Maintaining the frozen state: By scientifically controlling the temperature and flow rate of the freezing liquid, the frozen state is maintained, the integrity of the freezing curtain is maintained, and the risk of water leakage is reduced; S5. Management of shield excavation process: Shield excavation is carried out in the area surrounded by the freezing curtain to ensure that the shield avoids encountering unfrozen or insufficiently frozen strata during the receiving process, and a control system is used to ensure the safety and accuracy of the construction; S6, freezing pipe extraction and backfilling process: After the shield completes the reception, the freezing pipes are gradually extracted and backfilled in the freezing curtain to ensure that the thickness of the frozen body on the front of the tunnel is maintained within a safe range to prevent potential risks caused by the reduction of the frozen body; S7, grouting reinforcement: carry out efficient grouting in the steel sleeve, increase the back pressure of the plugging grouting, and ensure that the secondary grouting filling is more dense to further reduce the risk of surface settlement; S8. Foundation pit removal: After receiving the shield, carefully remove the foundation pit and take appropriate support measures to ensure the safety and stability of the surrounding environment during the construction process.

2. A construction method for receiving a subway shield in a special-shaped station in a sensitive urban area according to claim 1, characterized in that: The step S1 specifically includes the following steps: S101. Conduct detailed geological exploration, including investigations on groundwater conditions, soil structure, underground pipelines, etc. This will help understand the geological characteristics and determine whether there are special geological conditions, such as soft soil, rock formations, groundwater levels, etc., and their possible impact on shield construction; S102. Investigate the structural characteristics and foundation conditions of surrounding buildings, and assess the possible impact of shield construction on these buildings and structures to determine safety distances and protective measures; S103. Evaluate the surrounding environment, residents, traffic and other factors, consider the possible impact of construction on urban life and traffic, and formulate corresponding construction plans and safety measures; S104. Based on the aforementioned survey data and analysis results, use engineering simulation software or technology to plan the challenges and problems that may be encountered during shield construction and design a reasonable construction path and area scope; S105. Comply with relevant regulations and standards, follow urban planning, building regulations and relevant standards, ensure that the construction process complies with legal and regulatory requirements, and ensure safety and environmental protection in sensitive urban areas.

3. The construction method for receiving a subway shield in a special-shaped station in a sensitive urban area according to claim 1 is characterized in that: The step S2 specifically includes the following steps: S201. Determine the diameter of the steel sleeve to be set according to the specific shield machine model and diameter. The shield diameter is determined by the engineering design, and the sleeve diameter should be slightly larger than the shield diameter to accommodate the movement of the shield machine and uncertain factors during the construction process. S202, using precise measurement and positioning technology, such as a total station, a laser rangefinder, etc., to measure the receiving area, including determining the coordinates, depth, inclination, and other information of the center of the sleeve; S203. Based on the geological data and measurement results, design a reasonable sleeve layout plan, determine the spacing and distribution map between the sleeves, and ensure that the entire receiving area is fully covered; S204. After the measurement and design are completed, preparatory work before construction is carried out, including cleaning the work area, purchasing the required steel sleeve materials and equipment, to ensure the smooth progress of the construction process; S205. Use professional equipment and tools to install the steel sleeves one by one to the designated positions. During the installation process, ensure the verticality and horizontality of the sleeves to ensure the accuracy of subsequent shield construction; S206. After the sleeve is installed, quality control and inspection are carried out, including checking the position, depth, inclination and other parameters of the sleeve to ensure that they meet the design requirements.

4. The construction method for receiving a subway shield in a special-shaped station in a sensitive urban area according to claim 1 is characterized in that: The S3 step specifically includes the following steps: S301. Design the size, depth, density and other parameters of the freezing curtain according to geological exploration data and engineering requirements, taking into account the formation permeability and environmental conditions, and determining the type and performance of the cooling liquid; S302. Before the actual construction, a preliminary test is conducted to verify the diffusion and freezing effect of the freezing liquid in the formation, which is helpful to adjust the proportion and injection speed of the freezing liquid; S303, clean and prepare the inside of the steel sleeve to ensure that the surface is smooth and clean, and there are no impurities that affect the injection of the freezing liquid and the cooling effect; S304, using special equipment, injecting a freezing liquid into the steel sleeve through a pipeline, wherein the liquid is a mixture of efficient cooling, such as brine, ethylene glycol, etc., wherein the injection process needs to control the speed and pressure to ensure uniform filling and prevent leakage; S305. After injection, the circulation system is started to ensure that the freezing liquid flows evenly in the steel sleeve to promote heat transfer and accelerate formation freezing; S306. During the injection and cooling process, the temperature, flow rate and other parameters are continuously monitored, and the injection speed and the ratio of the cooling liquid are adjusted in a timely manner according to the monitoring results to ensure that the freezing effect reaches the expected level; S307. As time goes by, the freezing liquid gradually cools in the formation to form a solid freezing curtain, wherein this process takes weeks or even months, and the specific time depends on the characteristics of the formation and the performance of the cooling liquid; S308. After the freezing curtain is formed, stability monitoring is performed to ensure the firmness and durability of the freezing curtain to prevent the formation of water seepage channels.

5. The construction method for receiving a subway shield in a special-shaped station in a sensitive urban area according to claim 1 is characterized in that: The step S5 specifically includes the following steps: S501. Before excavation, conduct detailed geological surveys to understand the nature of the strata, including geological structure, soil characteristics, hydrogeological conditions, etc., to ensure that the coverage of the freezing curtain matches the actual situation of the strata; S502. During shield excavation, the temperature and integrity of the freezing curtain are continuously monitored, which helps to ensure the effectiveness of the freezing curtain and prevent unfrozen or insufficiently frozen strata from being encountered. Real-time monitoring of temperature and curtain integrity can be achieved through sensors and monitoring systems. S503, using an advanced control system to precisely control the freezing curtain, including controlling the temperature, flow rate and flow direction of the cooling liquid to ensure that the freezing curtain remains stable throughout the construction process; S504. Build numerical models and simulations to predict the performance and impact of freezing curtains, which can help engineering teams better understand the freezing process, predict possible ground reactions, and make timely adjustments in actual construction; S505. During the shield excavation process, a real-time monitoring system is used to monitor the position, posture, vibration and other parameters of the shield, which helps to detect any abnormal situation in time and take necessary measures to ensure the safety of construction; S506. Develop a detailed emergency response plan, including plans for possible ground conditions, to ensure that the team has the ability to handle unexpected situations, including unfrozen or insufficiently frozen ground conditions.

6. The construction method for receiving a subway shield in a special-shaped station in a sensitive urban area according to claim 1 is characterized in that: The step S6 specifically includes the following steps: S601. Before the freezing pipe is pulled out and backfilled, the temperature distribution and thickness of the frozen body shall be carefully measured and recorded through the monitoring system. This can be achieved by installing temperature and thickness sensors in the frozen body to ensure that the frozen body in the area in front of the tunnel portal is maintained within a safe range. S602, gradually pulling out the frozen pipes, usually in sections, to ensure the stability of the frozen body, wherein the speed and sequence of pulling out the pipes may need to be adjusted according to the actual freezing situation and engineering requirements, and while pulling out the pipes, monitor the changes of the frozen body to ensure that no abnormal situation occurs; S603. The material prepared for backfill is a material that can provide support and fill voids, wherein the backfill material includes concrete, expansive soil or similar supporting materials. Ensure that the backfill material meets the engineering requirements and can provide sufficient support and stability; S604, injecting backfill material into the frozen body by grouting or other appropriate methods to ensure that each part is filled and any gaps that may exist are filled. During the backfilling process, the temperature and thickness of the frozen body are continuously monitored to ensure that the frozen body on the front of the tunnel portal is maintained within a safe range; S605. Adjust the operation during the backfilling process at any time according to the real-time monitoring data, including adjusting the injection speed, position and pressure of the backfilling material to ensure the stability of the frozen body.

7. The construction method for receiving a subway shield in a special-shaped station in a sensitive urban area according to claim 1 is characterized in that: The step S7 specifically includes the following steps: S701. Install steel sleeves at locations that require reinforcement. The diameter and length of the sleeves should meet the requirements of the engineering design and be able to accommodate grouting equipment. S702. Arrange grouting pipes inside the sleeve to ensure that they cover the entire reinforcement area. The location and arrangement of the grouting pipes should be determined according to geological exploration and design requirements; S703. After the grouting pipe is arranged, preparation for plugging is carried out, which includes selecting appropriate plugging materials, such as expansive soil, cement slurry, etc.; S704, then grouting is performed, and the grouting pressure is gradually increased so that the plugging material fills the gap around the sleeve. By increasing the grouting back pressure, the plugging effect can be improved to ensure that the plugging material is fully filled into the formation; S705. During the grouting process, the grouting parameters are adjusted in time by real-time monitoring of the grouting pressure, flow rate, stratum deformation and other parameters to ensure the stability and effectiveness of the grouting process; S706. After the initial grouting is completed, secondary grouting is performed to fill more materials and improve the stability of the formation. In the secondary grouting, the grouting pressure also needs to be gradually increased to ensure a denser filling.

8. The construction method for receiving a subway shield at a special-shaped station in a sensitive urban area according to claim 1 is characterized in that: The step S7 also includes: when the grouting volume and formation stability required by the design are reached, the grouting process is ended, and the grouting pressure is gradually reduced to ensure that the grouting pipe does not produce backflow. After the grouting is completed, the grouting pipe is cleaned to prevent the material from solidifying and clogging the pipe. Then, the grouting equipment and sleeve can be removed.

9. The construction method for receiving a subway shield in a special-shaped station in a sensitive urban area according to claim 1, characterized in that: Taking appropriate support measures in step S8 includes installing and maintaining appropriate support structures, such as support frames, support walls, etc., to prevent soil collapse and collapse.