A construction method for controlling stratum deformation of a subway tunnel face

Abstract

A subway tunnel face excavation stratum deformation control construction method, including construction pre-geological survey, integrated hole arrangement of dewatering hole and grouting hole, hierarchical dynamic advanced dewatering, dewatering-grouting synchronous collaborative construction, grouting pressure stabilization hole sealing and dewatering hierarchical shutdown, CRD method four-part step-by-step excavation and immediate support, surrounding rock forming monitoring and cyclic construction, through the water-rich stratum face instability evolution law implementation whole process dynamic regulation and control, combined with CRD method fine division excavation, can effectively inhibit stratum disturbance, strict control surface and tunnel structure deformation, realize complex urban environment under shallow buried excavation engineering safety, efficient, low deformation construction. Through the construction of integrated construction system of zoning hole arrangement, hierarchical dewatering, synchronous grouting, linkage regulation and control, realize the precise cooperation of dewatering pressure relief and grouting solidification, effectively solve the problems of water-rich soft stratum tunnel face grouting slurry loss, uneven surrounding rock reinforcement, water gushing collapse, settlement exceeding the standard.

Description

Technical Field

[0001] This invention relates to the field of construction technology for subway tunnel faces, and more particularly to a construction method for controlling ground deformation in the face of a subway tunnel during underground excavation. Background Technology

[0002] In the construction of urban subway tunnels, a large number of tunnels pass through complex and weak strata such as water-rich sand and gravel, soft soil, and fractured zones. These strata are characterized by high porosity, high permeability, and poor surrounding rock stability. During the excavation of the tunnel face, engineering problems such as water inrush, sand inrush, surrounding rock collapse, and excessive surface settlement are very likely to occur, which seriously threaten construction safety and the stability of surrounding buildings and structures.

[0003] Traditional subway tunnel construction typically employs a separate, step-by-step construction process, with dewatering followed by grouting. However, these two processes suffer from a significant disconnect. The initial dewatering process merely lowers the groundwater level, failing to accurately match the water pressure and moisture content requirements of the subsequent grouting. Excessive dewatering can lead to groundwater loss and consolidation, as well as premature surface subsidence. Insufficient dewatering results in excessively high water pressure at the tunnel face, causing the grout to be diluted and washed away by groundwater during subsequent grouting. This results in incomplete filling of surrounding rock fissures, defects in the water-stopping curtain, and a significant reduction in the effectiveness of reinforcement and water-stopping.

[0004] Meanwhile, traditional construction techniques use fixed preset values ​​for precipitation and grouting parameters, which cannot adapt to the complex conditions of uneven water content and varying seepage in the strata ahead of the tunnel face. Excessive grouting in dry areas leads to material waste, while insufficient grouting in water-rich areas poses safety hazards. The construction mode of independently controlled procedures and mismatched parameters results in low tunnel construction efficiency, poor reinforcement quality stability, and high safety risks, making it difficult to meet the requirements of refined and safe construction for urban subways. Summary of the Invention

[0005] To address the problems of water and mud inrush, tunnel face instability, excessive surface settlement, and interface structure deformation during underground excavation in shallow, water-rich, and soft strata, this invention provides a construction method for controlling strata deformation at the tunnel face of a subway tunnel.

[0006] The technical solution adopted by this invention to solve the above-mentioned technical problems is: a construction method for controlling the deformation of strata in the face of a subway tunnel, comprising the following steps: Step 1: Geological Survey in the Pre-Construction Phase The strata in front of the tunnel face of the subway tunnel were explored, and the core water-rich zone, the transitional seepage zone and the dry and stable zone were divided on the tunnel face. The core water-rich zone is a trapezoidal area close to the bottom of the tunnel face, the transitional seepage zone is an inverted V-shaped area above the core water-rich zone, and the dry and stable zone is located above the transitional seepage zone and close to the tunnel face arch. Step 2: Integrated layout of dewatering holes and grouting holes Multiple dewatering holes and grouting holes are machined at intervals on the working face. The openings of the multiple dewatering holes are located inside or at the boundary of the core water-rich zone. The openings of the multiple grouting holes are located inside or at the boundary of the core water-rich zone, the transitional seepage zone, and the dry and stable zone. The grouting holes and dewatering holes located in the core water-rich zone are divided into multiple semi-circular layers arranged radially at intervals around the midpoint of the trapezoidal base of the core water-rich zone. The grouting holes at the tunnel face have a diameter of 50-70mm and are divided into shallow reinforcement holes and deep curtain holes. The shallow reinforcement holes extend into the surface surrounding rock of the tunnel face, while the deep curtain holes extend to the water-resistant layer outside the tunnel. The dewatering holes have a diameter of 80-110mm and are laid out in an obliquely advanced manner, extending from the tunnel face in an oblique upward direction. The depth of the dewatering holes exceeds the tunnel excavation outline by 3-5m. Step 3: tiered dynamic advance precipitation Multiple vertically downward surface grouting holes are machined at intervals 5-6m behind the working face. Dewatering wells extending vertically downward are machined on both sides of the working face. The edge of the dewatering well is 1.5-2.5m away from the side wall of the working face. The dewatering well is filled with quartz sand filter material and equipped with a filter pipe. The top of the filter pipe is connected to the surface water collection equipment, and the bottom of the filter pipe is connected to the sedimentation pipe at the bottom of the dewatering well. The bottom of the sedimentation pipe is sealed to prevent sand from clogging the dewatering well. The well wall of the dewatering well is provided with an annular clay filling area to prevent surface water from flowing back into the dewatering well. A staged dynamic pre-rainfall precipitation model is adopted. The first stage involves surface pre-rainfall, where water is pumped from the precipitation wells through filter pipes to the surface water collection equipment, with the precipitation flow rate controlled at 2-4 m³ / h. 3 The first stage involves a slow, gradual reduction of pore water pressure in the formation ahead of the tunnel face, lasting 20-30 minutes, to eliminate instantaneous water pressure impacts. The second stage, based on pre-rainwatering at the surface, involves pressure-stabilizing precipitation at the tunnel face. This is achieved by gradually increasing the precipitation flow rate to 6-10 m³ / h through multiple semi-circular precipitation holes spaced radially at intervals. 3 / h, so that the groundwater level drops to 1.5~2.5m below the tunnel excavation outline and the stratum moisture content in the construction area reaches a stable state of 3%~6%; Step 4: Simultaneous and coordinated construction of dewatering and grouting First, grouting is performed on the surface grouting holes using grouting equipment. Then, layered gradient grouting is performed on the working face through grouting holes. During the grouting process, low-speed, pressure-stabilized dewatering is carried out simultaneously through dewatering holes. During construction, the formation seepage flow, groundwater level, dewatering flow, and grouting pressure are continuously monitored. When the formation seepage flow increases or the water level rises abnormally, the dewatering flow is increased and the grouting pressure is increased simultaneously to achieve a dynamic balance between dewatering pressure relief and grout solidification. This replaces the water source around the channel within the formation with grout and simultaneously offsets the changes in formation pore water pressure caused by grouting. Step 5: Grouting, pressure stabilization, hole sealing, and graded shutdown of dewatering. After grouting is completed, maintain grouting pressure for 30-60 minutes, and then shut down the dewatering system in stages to avoid cracking and voids in the grouting layer caused by instantaneous water level rise. Step Six: CRD Method Four-Section Step-by-Step Excavation and Immediate Support A support arch is installed on the outside of the tunnel face, and a cross-shaped partition plate is installed inside the support arch to divide the tunnel face into four areas: the upper left excavation area, the upper right excavation area, the lower left excavation area, and the lower right excavation area. Excavation is carried out in the order of top to bottom, left and right staggered, and step-by-step closure. The single excavation advance of each area is controlled at 0.5m to 0.8m, and the excavation interval between adjacent areas is not less than 4 hours. Step 7: Surrounding Rock Formation Monitoring and Cyclic Construction After completing the single-cycle dewatering and grouting coordinated construction, monitor the settlement, seepage, and reinforcement density of the surrounding rock at the tunnel face. Once the standards are met, proceed with short-cut tunnel excavation. After excavation, repeat the above steps to carry out the next cycle of coordinated construction.

[0007] Preferably, in step four, the water collected by the water collection device is transported to the grouting device as grouting water.

[0008] Preferably, the controlled construction method is characterized in that: in step four, the core water-rich zone uses a cement-water glass double-liquid fast-setting grout with a water-cement ratio of 0.8:1 to 1:1, a water glass concentration of 35 to 40 Be′, and a grouting pressure of 1.8 to 2.5 MPa; the transitional seepage zone uses a cement-water glass double-liquid fast-setting grout with a water-cement ratio of 1:1 to 1.2:1 and a grouting pressure of 1.2 to 1.8 MPa; and the dry stabilization zone uses cement grout with a grouting pressure of 0.8 to 1.2 MPa.

[0009] Preferably, in step five, the rainwater system is shut down in two stages: in the first stage, the rainfall flow is reduced by 50% and maintained for 15-20 minutes, and in the second stage, it is completely shut down.

[0010] Preferably, in step six, after the excavation of each area is completed, C25 concrete is immediately sprayed to seal the working face, and then steel arches are erected, steel mesh is laid, and connecting bars are welded.

[0011] Preferably, in step seven, the single-cycle excavation advance is controlled at 0.8~1.2m, and the daily settlement of the surrounding rock after construction is controlled within 0.5mm. The construction standard is that there is no concentrated water seepage or sand gushing at the working face.

[0012] According to the above technical solution, the beneficial effects of the present invention are: This invention constructs an integrated construction system encompassing zoned borehole layout, graded dewatering, simultaneous grouting, and coordinated control. This system achieves precise synergy between dewatering and grouting solidification, effectively suppressing ground disturbance and strictly controlling surface and tunnel structure deformation. It thoroughly solves the problems of water and mud inrush, grout loss at the tunnel face, uneven surrounding rock reinforcement, water inrush collapse, and excessive settlement during underground excavation in water-rich clayey silt-silt strata. The invention boasts a high construction safety factor, excellent ground deformation control, and mature, standardized technology. It can be widely applied to similar shallow-buried tunneling projects such as subway transfer passages, urban pedestrian tunnels, and underground utility tunnels, offering the following advantages: I. Controllable construction quality and thorough prevention and control of defects: Dewatering and grouting are carried out simultaneously and in coordination, the formation water pressure is stable throughout the process, the water-stopping and reinforcement effect of the surrounding rock is improved by more than 50%, the cracks in the surrounding rock are filled densely, which can completely avoid the construction defects of water and sand inrush at the working face and surrounding rock collapse, and eliminate the process defects of groundwater interfering with grouting reinforcement.

[0013] II. Wide adaptability to geological formations and precise parameter control: The zoned differentiated construction parameter control mode takes into account both the safety of geological reinforcement and the controllability of settlement, and can be adapted to various complex and weak geological formations such as water-rich sand and gravel and broken soft soil.

[0014] 3. Controllable stratum deformation and extremely low environmental disturbance: Relying on monitoring-linked dynamic control and improved CRD excavation technology, the stress of the surrounding rock is effectively dispersed, and the surface settlement can be controlled to within 60% of the standard limit. It is suitable for dense urban building clusters and sensitive construction areas with dense underground pipelines, and significantly reduces the disturbance to the surrounding environment of construction.

[0015] IV. Highly efficient and energy-saving construction, resulting in lower project costs: The grouting process is seamlessly connected, eliminating the waiting period between processes and increasing the efficiency of single-cycle construction by 30%; precise parameter control reduces the ineffective consumption of grouting materials and groundwater resources, effectively compressing material and construction period costs.

[0016] V. Stable and durable structure with high promotion value: The support system is subjected to balanced stress, has excellent anti-seepage and durability performance, and can ensure the structural stability of the tunnel during long-term operation; the process is compact, the construction error tolerance is high, the applicable working conditions are wide, the engineering is highly practical, and the industry-wide promotion value is high. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the present invention; Figure 2 This is a schematic diagram showing the distribution of dewatering holes and grouting holes; Figure 3 This is a schematic diagram of the four-section, step-by-step excavation.

[0018] The markings in the diagram are: 1. Arch, 2. Sidewall, 3. Bottom, 4. Supporting arch, 5. Core water-rich zone, 6. Transitional seepage zone, 7. Dry and stable zone, 8. Dewatering hole, 9. Grouting hole at the working face, 10. Surface grouting hole, 11. Dewatering well, 12. Filter pipe, 13. Sedimentation pipe, 14. Clay-filled zone, 15. Water collection equipment, 16. Grouting equipment, 17. Separator, 18. Upper left excavation zone, 19. Upper right excavation zone, 20. Lower left excavation zone, 21. Lower right excavation zone. Detailed Implementation

[0019] Referring to the attached diagram, the specific implementation method is as follows: A construction method for controlling ground deformation at the tunnel face of a subway tunnel includes the following steps: Step 1: Geological Survey in the Pre-Construction Phase The strata ahead of the subway tunnel face were explored, and the tunnel face was divided into a core water-rich zone (5), a transitional seepage zone (6), and a dry and stable zone (7). Figure 1 , 2 As shown, the core water-rich zone 5 is a trapezoidal area close to the bottom surface 3 of the working face, the transitional seepage zone 6 is an inverted V-shaped area above the core water-rich zone 5, and the dry and stable zone 7 is located above the transitional seepage zone 6 and close to the arch 1 of the working face.

[0020] Step 2: Integrated layout of dewatering holes 8 and grouting holes like Figure 2 As shown, multiple dewatering holes 8 and grouting holes 9 are processed at intervals on the working face. The openings of the multiple dewatering holes 8 are located inside or at the boundary of the core water-rich zone 5, and the openings of the multiple grouting holes 9 are located inside or at the boundary of the core water-rich zone 5, the transitional seepage zone 6, and the dry and stable zone 7, respectively. The grouting holes 9 and dewatering holes 8 located in the core water-rich zone 5 are divided into multiple semi-circular layers arranged radially at intervals around the midpoint of the trapezoidal base of the core water-rich zone 5.

[0021] The grouting holes 9 at the tunnel face have a diameter of 50~70mm and are divided into shallow reinforcement holes and deep curtain holes. The shallow reinforcement holes extend into the surface surrounding rock of the tunnel face, while the deep curtain holes extend to the water-resistant layer outside the tunnel. The dewatering holes 8 have a diameter of 80~110mm and are laid out in an obliquely advanced manner, extending from the tunnel face in an oblique upward direction. The depth of the dewatering holes 8 exceeds the tunnel excavation outline by 3~5m.

[0022] Step 3: tiered dynamic advance precipitation like Figure 1As shown, multiple vertically extending surface grouting holes 10 are machined at intervals 5-6m behind the working face. On both sides of the working face, vertically extending dewatering wells 11 are machined. The edge of the dewatering well 11 is 1.5-2.5m away from the side wall 2 of the working face. The dewatering well 11 is filled with quartz sand filter material and equipped with a filter pipe 12. The top end of the filter pipe 12 is connected to the surface water collection device 15, and the bottom end of the filter pipe 12 is connected to the sedimentation pipe 13 located at the bottom of the dewatering well 11. The bottom of the sedimentation pipe 13 is sealed to prevent sand from clogging the dewatering well 11. The well wall of the dewatering well 11 is provided with an annular clay filling area 14 to prevent surface water from flowing back into the dewatering well 11.

[0023] A staged dynamic pre-rainfall precipitation model is adopted. The first stage involves surface pre-rainfall, in which water is pumped from the precipitation well 11 through the filter pipe 12 to the surface water collection device 15 using a water pump. The precipitation flow rate is controlled at 2-4 m³ / h. 3 The first stage involves a slow, gradual reduction of pore water pressure in the formation ahead of the tunnel face, lasting 20-30 minutes, to eliminate instantaneous water pressure impact. The second stage, based on pre-rainwatering at the surface, involves pressure-stabilizing precipitation at the tunnel face. This is achieved by increasing the precipitation flow rate to 6-10 m³ / h through multiple semi-circular precipitation holes spaced radially at intervals. 3 / h, so that the groundwater level drops to 1.5~2.5m below the tunnel excavation outline and the soil moisture content in the construction area reaches a stable state of 3%~6%.

[0024] Step 4: Simultaneous and coordinated construction of dewatering and grouting First, the water collected by the water collection device 15 is transported to the grouting device 16 on the surface as grouting water. Grouting is then carried out through the grouting device 16 to the grouting holes 10 on the surface. Then, layered gradient grouting is carried out through the grouting holes 9 on the working face. During the grouting process, low-speed pressure-stabilized dewatering is carried out simultaneously through the dewatering holes 8. During the construction process, the stratum seepage flow, groundwater level, dewatering flow, and grouting pressure are continuously monitored. When the stratum seepage flow increases and the water level rises abnormally, the dewatering flow is increased and the grouting pressure is increased simultaneously to achieve a dynamic balance between dewatering pressure relief and grouting solidification. This replaces the water source around the channel in the stratum with grout and simultaneously offsets the changes in stratum pore water pressure caused by grouting.

[0025] The core water-rich zone 5 uses a cement-water glass dual-liquid fast-setting grout with a water-cement ratio of 0.8:1 to 1:1, a water glass concentration of 35 to 40 Be′, and a grouting pressure of 1.8 to 2.5 MPa; the transitional seepage zone 6 uses a cement-water glass dual-liquid fast-setting grout with a water-cement ratio of 1:1 to 1.2:1 and a grouting pressure of 1.2 to 1.8 MPa; and the dry and stable zone 7 uses cement grout with a grouting pressure of 0.8 to 1.2 MPa.

[0026] Step 5: Grouting, pressure stabilization, hole sealing, and graded shutdown of dewatering. After grouting is completed, maintain grouting pressure for 30-60 minutes, and then shut down the dewatering system in stages. In the first stage, reduce the dewatering flow by 50% and maintain it for 15-20 minutes. In the second stage, shut it down completely to avoid cracking and voiding of the grouting layer caused by instantaneous water level rise.

[0027] Step Six: CRD Method Four-Section Step-by-Step Excavation and Immediate Support like Figure 1 , 3 As shown, a support arch 4 is set on the outside of the tunnel face, and a cross-shaped partition plate 17 is set inside the support arch 4 to divide the tunnel face into four areas: upper left excavation area 18, upper right excavation area 19, lower left excavation area 20, and lower right excavation area 21. Excavation is carried out in the order of top to bottom, left and right staggered, and step-by-step closure. The single excavation advance of each area is controlled at 0.5m to 0.8m, and the excavation interval between adjacent areas is not less than 4 hours.

[0028] After the excavation of each area is completed, a 4cm thick layer of C25 concrete is immediately sprayed to seal the working face. Then, I20b steel arch frames are erected with a spacing of 0.5m to 0.8m. φ8@200mm steel mesh is laid and connecting bars are welded.

[0029] Step 7: Surrounding Rock Formation Monitoring and Cyclic Construction After completing the single-cycle dewatering and grouting coordinated construction, monitor the settlement, seepage, and reinforcement density of the surrounding rock at the tunnel face. Once the standards are met, proceed with short-cut tunnel excavation. After excavation, repeat the above steps to carry out the next cycle of coordinated construction.

[0030] In this embodiment, the single-cycle excavation advance is controlled at 0.8~1.2m, and the daily settlement of the surrounding rock after construction is controlled within 0.5mm. The construction standard is that there is no concentrated water seepage or sand gushing at the working face.

[0031] This embodiment implements dynamic control throughout the entire process by understanding the instability evolution of the tunnel face in water-rich strata. Combined with the CRD method for refined sectional excavation, it effectively suppresses stratum disturbance and strictly controls surface and tunnel structure deformation, achieving safe, efficient, and low-deformation construction of shallow-buried tunnel projects in complex urban environments. By constructing an integrated construction system of zoned borehole layout, graded dewatering, synchronous grouting, and coordinated control, it achieves precise coordination between dewatering and grouting solidification, effectively solving the problems of grout loss, uneven surrounding rock reinforcement, water inrush and collapse, and excessive settlement in tunnel faces in water-rich and soft strata.

Claims

1. A construction method for controlling ground deformation at the tunnel face of a subway tunnel, characterized in that, Includes the following steps: Step 1: Geological Survey in the Pre-Construction Phase The strata in front of the tunnel face of the subway tunnel were explored, and the core water-rich area (5), the transitional seepage area (6) and the dry and stable area (7) were divided on the tunnel face. The core water-rich area (5) is a trapezoidal area close to the bottom surface (3) of the tunnel face. The transitional seepage area (6) is an inverted V-shaped area located above the core water-rich area (5). The dry and stable area (7) is located above the transitional seepage area (6) and close to the tunnel face arch (1). Step 2: Integrated layout of dewatering holes (8) and grouting holes Multiple dewatering holes (8) and grouting holes (9) are processed at intervals on the working face. The openings of the multiple dewatering holes (8) are located inside or at the boundary of the core water-rich area (5). The openings of the multiple grouting holes (9) are located inside or at the boundary of the core water-rich area (5), the transitional seepage area (6), and the dry and stable area (7). The grouting holes (9) and dewatering holes (8) located in the core water-rich area (5) are divided into multiple semi-circular layers arranged radially at intervals around the midpoint of the trapezoidal bottom edge of the core water-rich area (5). The diameter of the grouting holes (9) at the tunnel face is 50~70mm. They are divided into shallow reinforcement holes and deep curtain holes. The shallow reinforcement holes extend into the surface surrounding rock of the tunnel face, and the deep curtain holes extend to the water-proof layer outside the tunnel. The diameter of the dewatering holes (8) is 80~110mm. The dewatering holes (8) are laid out in an oblique and advanced manner, extending from the tunnel face in an oblique upward direction. The depth of the dewatering holes (8) exceeds the tunnel excavation outline by 3~5m. Step 3: tiered dynamic advance precipitation Multiple vertically extending surface grouting holes (10) are processed at intervals 5-6m behind the working face. On both sides of the working face, vertically extending dewatering wells (11) are processed. The distance between the edge of the dewatering well (11) and the side wall (2) of the working face is 1.5-2.5m. The dewatering well (11) is filled with quartz sand filter material and is equipped with a filter pipe (12). The top of the filter pipe (12) is connected to the surface water collection device (15). The bottom of the filter pipe (12) is connected to the sedimentation pipe (13) at the bottom of the dewatering well (11). The bottom of the sedimentation pipe (13) is sealed to prevent the sediment from clogging the dewatering well (11). The well wall of the dewatering well (11) is provided with an annular clay filling area (14) to prevent surface water from flowing back into the dewatering well (11). A staged dynamic advance precipitation method is adopted, using a graded pressure relief precipitation mode. In the first stage, surface pre-precipitation is carried out. Water is pumped from the precipitation well (11) through the filter pipe (12) to the surface water collection device (15) using a water pump. The precipitation flow rate is controlled at 2~4m 3 / h, lasting for 20~30min, thereby slowly reducing the pore water pressure in the formation ahead of the tunnel face and eliminating the instantaneous water pressure impact in the formation; the second stage is to carry out pressure stabilization precipitation at the tunnel face based on the pre-precipitation on the ground, and increase the precipitation flow rate to 6~10m through multiple semi-circular precipitation holes (8) arranged radially at intervals. 3 / h, so that the groundwater level drops to 1.5~2.5m below the tunnel excavation outline and the stratum moisture content in the construction area reaches a stable state of 3%~6%; Step 4: Simultaneous and coordinated construction of dewatering and grouting First, grouting is carried out on the surface grouting holes (10) through the grouting equipment (16) on the surface. Then, the working face is grouted in layers through the grouting holes (9). During the grouting process, low-speed pressure stabilization and dewatering are carried out simultaneously through the dewatering holes (8). During the construction process, the stratum seepage flow, groundwater level, dewatering flow and grouting pressure are continuously monitored. When the stratum seepage flow increases and the water level rises abnormally, the dewatering flow is increased and the grouting pressure is increased simultaneously to achieve a dynamic balance between dewatering pressure relief and grouting solidification. In this way, the grout replaces the water source around the channel in the stratum and simultaneously offsets the changes in stratum pore water pressure caused by grouting. Step 5: Grouting, pressure stabilization, hole sealing, and graded shutdown of dewatering. After grouting is completed, maintain grouting pressure for 30-60 minutes, and then shut down the dewatering system in stages to avoid cracking and voids in the grouting layer caused by instantaneous water level rise. Step Six: CRD Method Four-Section Step-by-Step Excavation and Immediate Support A support arch frame (4) is set on the outside of the tunnel face, and a cross-shaped partition plate (17) is set inside the support arch frame (4) to divide the tunnel face into four areas: the upper left excavation area (18), the upper right excavation area (19), the lower left excavation area (20), and the lower right excavation area (21). Excavation is carried out in the order of first top and then bottom, left and right staggered, and step-by-step closure. The single excavation advance of each area is controlled at 0.5m~0.8m, and the excavation interval between adjacent areas is not less than 4 hours. Step 7: Surrounding Rock Formation Monitoring and Cyclic Construction After completing the single-cycle dewatering and grouting coordinated construction, monitor the settlement, seepage, and reinforcement density of the surrounding rock at the tunnel face. Once the standards are met, proceed with short-cut tunnel excavation. After excavation, repeat the above steps to carry out the next cycle of coordinated construction.

2. The construction method for controlling ground deformation at the tunnel face of a subway tunnel according to claim 1, characterized in that: In step four, the water collected by the water collection device (15) is transported to the grouting device (16) as grouting water.

3. The construction method for controlling ground deformation at the tunnel face of a subway tunnel according to claim 1, characterized in that: In step four, the core water-rich zone (5) uses cement-water glass double-liquid fast-setting grout with a water-cement ratio of 0.8:1~1:1, a water glass concentration of 35~40Be′, and a grouting pressure of 1.8~2.5MPa; the transitional seepage zone (6) uses cement-water glass double-liquid fast-setting grout with a water-cement ratio of 1:1~1.2:1 and a grouting pressure of 1.2~1.8MPa; and the dry and stable zone (7) uses cement grout with a grouting pressure of 0.8~1.2MPa.

4. The construction method for controlling ground deformation at the tunnel face of a subway tunnel according to claim 1, characterized in that: In step five, the precipitation system is shut down in two stages. In the first stage, the precipitation flow is reduced by 50% and maintained for 15-20 minutes. In the second stage, the system is completely shut down.

5. The construction method for controlling ground deformation at the tunnel face of a subway tunnel according to claim 1, characterized in that: In step six, after the excavation of each area is completed, C25 concrete is immediately sprayed to seal the working face, and then steel arches are erected, steel mesh is laid, and connecting bars are welded.

6. The construction method for controlling ground deformation at the tunnel face of a subway tunnel according to claim 1, characterized in that: In step seven, the single-cycle excavation advance is controlled at 0.8~1.2m, and the daily settlement of the surrounding rock after construction is controlled within 0.5mm. The construction standard is that there is no concentrated water seepage or sand gushing at the working face.

Images