Semi-ring grouting shield tunnel for deep muddy soil stratum and construction method

Abstract

The invention provides a semi-ring grouting shield tunnel for a deep muddy soil stratum and a construction method thereof. Through an in-hole semi-ring grouting reinforcement technology, a double-liquid grouting efficient stirring and cleaning technology, an intensive secondary grouting technology, a deep hole grouting rapid hole-forming technology, a shield tail sealing technology and a reserved hole follow-up secondary grouting technology, a semi-ring grouting shield tunnel is constructed; stable starting, efficient grouting and accurate settlement control of the shield tunnel in the deep and thick silt stratum are achieved, the grouting compactness and reinforcing efficiency are remarkably improved, and the risks of slurry fluid channeling, pipeline blocking, shield tail slurry leakage and the like are effectively prevented. Through a multi-stage, partitioned and synchronized grouting mode, the method greatly reduces the stratum disturbance, reduces the settlement around the tunnel, improves the shield tunneling quality, and provides a safe, reliable and efficient systematic solution for shield construction under the complex and soft stratum condition.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel engineering, and in particular to a grouting reinforcement construction method for shield tunnels suitable for deep silty soil strata. Background Technology

[0002] In the construction of urban rail transit and municipal tunnels, shield tunnels often need to traverse deep, soft strata such as silty clay and silty mud. These strata have high water content, low strength, high compressibility, and insufficient self-stabilizing capacity, making them highly susceptible to excessive settlement, quicksand formation, or surrounding rock instability during shield tunneling. Although synchronous grouting at the shield tail is currently the main measure to control stratum deformation, the grout diffusion is uneven, consolidation is slow, and segregation is severe in silty mud, making it difficult to fill the gaps at the shield tail in time. This often leads to segment instability and excessive tunnel settlement.

[0003] Traditional secondary grouting methods rely on manual point-by-point grouting, which is slow, inefficient, and unable to quickly control settlement. Controlling the shield tunnel's attitude in silty clay is challenging, as segments are prone to misalignment, rotation, or overall displacement. Existing segment integration or reinforcement measures lack overall integrity and are ill-suited for continuous tunneling over long distances in soft strata. Therefore, there is an urgent need for a shield tunneling method that can adapt to the characteristics of deep silty clay strata, effectively controlling ground settlement and improving shield tunneling safety and construction efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a semi-circular grouting shield tunnel and its construction method in deep silty soil strata. This construction method has the characteristics of high grouting efficiency, good tunneling accuracy, good settlement control, and high construction safety.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: The construction method for a semi-circular grouting shield tunnel in deep silty soil strata includes the following steps: Step 1: Grouting reinforcement of the semi-ring inside the tunnel: To address the issue of insufficient space in the launching shaft, a semi-ring launching method is adopted; firstly, semi-ring assembled segments with channeled steel pads are laid in the lower part of the launching space on the inner wall of the shield tail; at the same time, a reinforcing ring beam is set on the outside of the assembled full-ring segment, and then concrete is poured into the bottom of the semi-ring assembled segment to complete the grouting reinforcement of the semi-ring assembled segment area. Step 2: Two-component grouting and mixing construction; Step 3, Intensive Secondary Grouting Construction: The grouting trolley is moved to the grouting work point inside the tunnel to carry out grouting operations; the grouting trolley integrates a mixer and a grouting pump, and cement slurry and water glass are introduced into the mixer through the cement slurry inlet and water glass inlet respectively, and mixed evenly by the mixer to obtain a mixed slurry; the flow rate of the slurry is regulated by the control valves on the cement slurry inlet and water glass inlet, and the feed pressure is monitored in real time by the pressure gauge, and then the grouting pump delivers the mixed slurry to the grouting area; Step 4: Rapid Deep Hole Grouting Construction: The outer casing is pre-embedded in the grouting construction area. During grouting, the grouting rod with rubber threads is inserted into the outer casing, and the grout is delivered through the grouting rod. The check valve at the front end of the grouting rod is used to prevent the grout from flowing back. After grouting is completed, the water-swellable coil set on the outside of the grouting rod expands when it comes into contact with water, so that the water-swellable coil is tightly fitted with the inner wall of the outer casing to form a seal. The screw cap is then tightened to seal the lower end of the outer casing. Step 5: Tunnel Boring Machine Tail Sealing Construction; Step 6: Follow-up secondary grouting construction.

[0006] Preferably, in step one, the first I-beam and the second I-beam are connected by an arc-shaped steel plate to form a segment support structure. The entire ring of assembled segments is placed on the segment support structure, and the entire ring of assembled segments is supported by the segment support structure.

[0007] Preferably, in step two, water glass and tap water are mixed using an automatic mixing tank. The automatic mixing tank includes a cylinder, with a stirring rod installed at the center of the cylinder. The stirring rod consists of a central shaft and mixing tank blades. A mixing tank motor is fixedly installed at the top edge of the cylinder. A first gear is installed on the motor shaft end of the mixing tank motor, and the first gear meshes with a second gear located on the upper end of the stirring rod to form a mixing tank gear set. When the mixing tank motor rotates, it drives the stirring rod to rotate through the mixing tank gear set. A slurry outlet is opened at the bottom of the cylinder, and two independent slurry inlets are provided at the top of the cylinder. The two slurry inlets at the top of the cylinder are a tap water inlet and a water glass inlet, respectively, for the separate injection of different slurries.

[0008] Preferably, in step two, during the dual-liquid grouting and mixing construction, the mixing tank motor drives the mixing tank gear set and rotates the mixing tank blades; tap water is introduced into the cylinder of the automatic mixing tank through the tap water inlet, and water glass is introduced into the cylinder of the automatic mixing tank through the water glass inlet. The tap water and water glass are rapidly mixed by the mixing tank blades in the cylinder to obtain a mixed slurry; the mixed slurry is injected into the grouting area; after the automatic mixing tank completes the mixing operation, the slurry outlet is closed, and clean water is introduced into the cylinder through the tap water inlet. The mixing tank blades are used to stir and rinse the inner wall of the cylinder at high speed. After cleaning, the slurry outlet is opened, and the wastewater is discharged through the slurry outlet.

[0009] As a preferred method, the specific method of step five is as follows: At the tail of the tunnel boring machine, grout is delivered through the grouting pipe, and impurities are cleaned by the fixed brush head and wire brush set at the tail of the shield, and grease is filled into the oil-filled gap ring through the oil injection pipe to form a sealing layer; during maintenance, the grease injection port of the flat duckbill-shaped grease injection gun is inserted into the bottom of the fixed brush head at the tail of the shield, and grease is injected into the tail of the shield through the high-pressure ball valve on the flat duckbill-shaped grease injection gun.

[0010] Preferably, the wire brush at the tail of the shield consists of two steel plates, one above the other, and a wire sandwiched between the two plates.

[0011] As a preferred method, the specific method for step six is ​​as follows: When the tunnel segment is inside the shield shell of the tunnel boring machine, a hole is opened at the top of the segment and a ball valve is installed, and a synchronous grouting port is equipped on the ball valve; during the segment assembly, adjacent segments are fastened together by segment bolts to form a complete ring structure; in the three segments about to exit the shield shell, the synchronous grouting ports on the first and second ring segments are connected to synchronous grouting pipes, and the synchronous grouting port on the third ring segment is connected to a water glass pump pipe; during shield tunneling, the ball valves on the segments are opened: the synchronous grouting pipes inject cement mortar into the synchronous grouting ports of the first and second ring segments, and the water glass pump pipe injects water glass slurry into the synchronous grouting port of the third ring segment, and the two slurries mix and harden behind the segments; when the segment exits the shield tail of the tunnel boring machine, if shrinkage or voids are found in the synchronous grouting slurry during monitoring, secondary grouting is initiated.

[0012] As a preferred method, during secondary grouting, the follow-up grouting pipe is connected to the synchronous grouting port on the segment, and grouting is carried out through the follow-up grouting pipe.

[0013] The semi-circular grouting shield tunnel and its construction method in deep silty soil strata were obtained from the construction method of semi-circular grouting shield tunnel in deep silty soil strata.

[0014] Compared with existing technologies, this technical solution has the following characteristics and beneficial effects: 1. This invention solves the problems of insufficient space, uneven stress, and large ground disturbance in traditional full-ring launching systems by forming a composite stability system through semi-ring grouting reinforcement, strengthening the ring beam, and supporting the I-beams. The reserved hoisting space and the semi-ring assembly method effectively improve the stability of the shield launching section and significantly reduce the risk of local tunnel deformation.

[0015] 2. This invention utilizes an integrated secondary grouting trolley, which integrates grout preparation, mixing, pressurization, and grouting functions. The pressure gauge has a detachable and washable structure to prevent damage due to cement grout blockage. The entire system can move synchronously with tunneling, ensuring the continuity and controllability of secondary grouting, reducing manual operation interference, and improving grouting quality.

[0016] 3. This invention enhances the seal by using an oil-filled void ring, a combination of wire brush cleaning, a grease injection structure, and a high-pressure grease injection gun, giving the shield tail seal higher wear resistance and contamination resistance. The structure of the upper and lower steel plates clamping the wire brush keeps the brush bristles in contact with the outer wall of the tunnel segment, further improving the sealing effect and effectively preventing tunnel segment delamination and ground subsidence caused by shield tail grout leakage.

[0017] 4. This invention combines synchronous grouting with secondary grouting by setting independent grouting ball valves for different ring number segments, enabling rapid on-site mixing and solidification of cement mortar and water glass, thereby significantly improving the timeliness of filling the voids behind the segments. Compared with traditional secondary grouting, this technology reduces process overlap, lowers the risk of grout leakage, and improves grout compactness and settlement control. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the installation of the shield tunnel semi-ring segment pads.

[0019] Figure 2 This is a schematic diagram of the reinforcement arrangement of the semi-ring starting negative ring.

[0020] Figure 3 This is a schematic diagram of an automatic mixing tank.

[0021] Figure 4 This is a schematic diagram of an intensive secondary grouting system.

[0022] Figure 5 This is a schematic diagram of the pre-embedded grouting holes for the tunnel segments.

[0023] Figure 6 This is a schematic diagram of the shield tail seal structure.

[0024] Figure 7 This is a schematic diagram of a flat duckbill-shaped grease gun.

[0025] Figure 8 This is a schematic diagram of follow-up secondary grouting.

[0026] In the diagram: 1- Semi-ring assembled segment; 2- Shield tail inner wall; 3- Channel steel pad; 4- Full ring assembled segment; 5- Reinforcing ring beam; 6- Curved steel plate; 7- First I-beam; 8- Second I-beam; 9- C20 plain concrete; 10- Mixing drum gear set; 11- Mixing drum fan blade; 12- Tap water inlet; 13- Water glass inlet; 14- Fixing bolt; 15- Mixing drum motor; 16- Mixing rod fixing member; 17- Grout outlet; 18- Grouting trolley; 19- Cement slurry inlet; 20- Pressure gauge; 21- Control valve; 22- Water glass 23-Inlet; 24-Agitator; 25-Grouting pump; 26-Outer sleeve; 27-Water-expanding coil; 28-Screw cap; 29-Rubber thread; 30-Grouting rod; 31-Check valve; 32-Grouting pipe; 33-Fixed brush head; 34-Grouting liquid; 35-Oil injection pipe; 36-Wire brush; 37-Flat duckbill-shaped grease inlet; 38-Flat duckbill-shaped grease gun; 39-High-pressure ball valve; 40-Handrail; 41-Synchronous grouting port; 42-Segment bolt; 43-Fixed channel steel; 44-Follow-up grouting pipe; 45-Grouting outlet pipe. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0028] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0029] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0030] Example 1: This invention relates to a semi-ring grouting shield tunnel in a deep silty soil stratum. During its construction, it employs in-tunnel semi-ring grouting reinforcement technology, dual-liquid grouting high-efficiency mixing and cleaning technology, intensive secondary grouting technology, deep hole grouting rapid hole formation technology, shield tail sealing technology, and pre-reserved hole follow-up secondary grouting technology.

[0031] like Figure 1 , Figure 2 As shown, a semi-ring assembled segment 1 is arranged in the lower part of the launching space corresponding to the inner wall 2 of the shield tail. Several channel steel blocks 3 are set between the outer side of the semi-ring assembled segment 1 and the inner wall 2 of the shield tail. The channel steel blocks 3 are used to adjust the gap with the shield tail and the stress surface. A reinforcing ring beam 5 is set on the outer side of the full-ring assembled segment 4, and the first I-beam 7 and the second I-beam 8 are rigidly connected by an arc-shaped steel plate 6 to form a segment support structure with overall longitudinal and transverse stress. The width of the first I-beam 7 is 200mm, and the width of the second I-beam 8 is 200mm. After the support structure is stable, C20 plain concrete 9 is poured into the back and bottom gaps of the segments in the semi-ring assembled area through grouting equipment to form a continuous reinforced body, which improves the deformation resistance of the launching section and the structural stability in the early stage of shield advancement.

[0032] like Figure 3 As shown, the automatic mixing tank includes a cylindrical body, with a stirring rod mounted at the center of the cylinder. The stirring rod consists of a central shaft and mixing tank blades 11. A mixing tank motor 15 is fixedly installed at the top edge of the cylindrical body. A first gear is mounted on the motor shaft of the mixing tank motor 15, and the first gear meshes with a second gear located on the upper end of the stirring rod to form a mixing tank gear set 10. When the mixing tank motor 15 rotates, it drives the stirring rod to rotate through the mixing tank gear set 10. A stirring rod fixing rod 16 is welded to the inner wall of the cylindrical body, which positions and supports the central shaft of the stirring rod. A slurry outlet 17 is opened at the bottom of the cylindrical body, and two independent slurry inlets are provided at the top of the cylindrical body. The two slurry inlets at the top of the cylindrical body are a tap water inlet 12 and a water glass inlet 13, respectively, for the separate injection of different slurries. The entire cylindrical body is installed on the support structure by fixing bolts 14 to ensure good stability of the device during slurry injection and cleaning.

[0033] like Figure 4As shown, the integrated grouting trolley 18 is moved to the grouting work point inside the tunnel for grouting operations. The grouting trolley 18 is equipped with a mixer 23 and a grouting pump 24. The input end of the grouting pump 24 is equipped with a cement slurry inlet 19 and a water glass inlet 22. The output end of the grouting pump 24 is connected to the input end of the mixer 23 via a pipeline. A pressure gauge 20 is installed at the input end of the grouting pump 24. Control valves 21 are installed on the water glass inlet 22 and the cement slurry inlet 19. The output end of the mixer 23 is equipped with a slurry outlet pipe 45. After connecting the pipeline, raw materials are injected into the mixer 23 through the cement slurry inlet 19 and the water glass inlet 22, respectively, and thoroughly mixed using the mixer 23. The operator precisely adjusts the control valve 21 to control the slurry ratio and flow rate by observing the real-time reading of the pressure gauge 20. The grouting pump 24 provides stable pressure, pumping the uniformly mixed slurry to the gaps behind the tunnel segments for filling and reinforcement.

[0034] like Figure 5 As shown, the assembled casing structure is placed into a pre-set grouting hole. The casing structure includes an outer casing 25 and a grouting rod 29 disposed within the outer casing 25. A check valve 30 is provided at the front end of the grouting rod 29 to effectively prevent grout backflow. A water-swellable coil 26 is installed on the outer side of the grouting rod 29. During grouting, grout is injected into the formation through the grouting rod 29, and the grout passes through the check valve 30 into the target area. Simultaneously, the seeping grout or groundwater activates the water-swellable coil 26 on the outer casing 25, causing it to expand rapidly and form a tight seal against the inner wall of the outer casing 25. The grouting rod 29 is composed of several grouting rod units connected together, with adjacent grouting rods 29 connected by rubber threads 28. A screw cap 27 is provided at the lower end of the outer casing 25.

[0035] like Figure 6 , Figure 7 As shown, at the tail of the tunnel boring machine (TBM), a main sealing layer is formed by multiple fixed brush heads 32 and wire brushes 36. Grease is continuously injected into the oil-filled void ring 33 through the oil injection pipe 35 to enhance the sealing effect. During sealing, a flat duckbill-shaped grease gun 38 is connected to the grease injection port 37, and the pressure is controlled by a high-pressure ball valve 39 to replenish special grease into the void ring, effectively preventing the grout 34 from leaking forward. At the same time, grout 34 is injected into the gap at the tail of the TBM through an independent grouting pipe 31 to form a stable mud film, which works in conjunction with the sealing system to form a highly efficient and reliable multi-layer tail sealing system. The wire brush 36 at the tail consists of two steel plates and a steel wire sandwiched between them.

[0036] like Figure 8As shown, during the tunnel boring machine (TBM) excavation, the initial grouting is completed through the prefabricated synchronous grouting port 41 on the tunnel segments. During segment assembly, adjacent segments are fastened together by segment bolts 42 to form a complete ring structure, and auxiliary support is provided for the segments by fixing channel steel 43. If monitoring detects shrinkage or voids in the synchronous grouting slurry, secondary grouting is initiated. During secondary grouting, the follow-up grouting pipe 44 is connected to the synchronous grouting port 41 on the tunnel segment, and pressure grouting is supplemented through the follow-up grouting pipe 44.

[0037] A construction method for a semi-circular grouting shield tunnel in deep silty soil strata includes the following steps: Step 1: In-tunnel semi-ring grouting reinforcement construction: Addressing the insufficient space in the launching shaft, a semi-ring launching method is adopted. Seven negative ring segments are selected for semi-ring assembly, leaving seven complete rings, with space reserved for hoisting. First, semi-ring assembled segments 1 with channeled steel pads 3 are laid at the lower part of the launching space on the inner wall 2 of the shield tail. Simultaneously, a reinforcing ring beam 5 is installed on the outside of the already assembled complete ring assembled segments 4. An arc-shaped steel plate 6 connects the first I-beam 7 and the second I-beam 8 to form a segment support structure. The complete ring assembled segments 4 are placed on the segment support structure, which supports them. Then, C20 plain concrete 9 is poured into the bottom of the semi-ring assembled segments 1 to complete the grouting reinforcement of the semi-ring assembled segments 1 area, improving the local structural stability of the tunnel.

[0038] Step 2, High-efficiency mixing construction of dual-liquid grouting: Water glass and tap water are mixed in an automatic mixing tank; the mixing tank motor 15 drives the mixing tank gear set 10 and drives the mixing tank fan blades 11 to rotate; tap water is introduced into the cylinder of the automatic mixing tank through the tap water inlet 12, and water glass is introduced into the cylinder of the automatic mixing tank through the water glass inlet 13. The tap water and water glass are rapidly mixed in the cylinder by the mixing tank fan blades 11 to obtain a mixed slurry; the mixed slurry is injected into the grouting area; after the automatic mixing tank completes the mixing operation, the slurry outlet 17 is closed, and clean water is introduced into the cylinder through the tap water inlet 12. The mixing tank fan blades are used to stir and rinse the inner wall of the cylinder at high speed. After cleaning, the slurry outlet 17 is opened, and the wastewater is discharged through the slurry outlet 17. Step 3: Integrated Secondary Grouting Construction: The grouting trolley 18 is moved to the grouting work point inside the tunnel to carry out the grouting operation. The grouting trolley 18 integrates a mixer 23 and a grouting pump 24. Cement slurry and water glass are introduced into the mixer 23 through the cement slurry inlet 19 and the water glass inlet 22, respectively. The two slurries are mixed evenly by the mixer 23 to obtain a mixed slurry. The flow rate of the slurry is regulated by the control valves 21 on the cement slurry inlet 19 and the water glass inlet 22. The feed pressure is monitored in real time by the pressure gauge 20. Then, the grouting pump 24 accurately delivers the mixed slurry to the grouting area. The entire system is integrated on the grouting trolley 18, which is easy to move and realizes the integrated operation of slurry preparation, transportation and grouting, improving the efficiency and accuracy of secondary grouting.

[0039] Step 4: Rapid Deep Hole Grouting Construction: The outer casing 25 is pre-embedded within the grouting area. During grouting, the grouting rod 29 with rubber threads 28 is inserted into the outer casing 25, and grout is delivered through the grouting rod 29. The check valve 30 at the front end of the grouting rod 29 prevents grout backflow. After grouting, the water-swellable coil 26 located outside the grouting rod 29 expands upon contact with water, forming a tight seal between the coil and the inner wall of the outer casing 25. The screw cap 27 is then tightened to seal the lower end of the outer casing 25. When tightening the screw cap 27, the lower end of the grouting rod 29 is aligned with the groove at the top of the screw cap 27. The grouting rod 29 rotates at low speed, and through torque transmission, the screw cap 27 is gradually screwed in along the threads of the grouting hole in the segment, achieving a tight seal. By pre-embedding the casing and cooperating with sealing components, precise delivery and subsequent sealing of grouting are achieved, adapting to the anti-seepage and reinforcement requirements of internal grouting and improving the sealing performance and reliability of grouting operations.

[0040] Step 5, Tunnel Boring Machine Tail Sealing Construction: At the tail of the tunnel boring machine, grout 34 is delivered through grouting pipe 31. Impurities are cleaned by a fixed brush head 32 and a wire brush 36 located at the tail of the shield. Grease is then filled into the oil-filled void ring 33 through oil injection pipe 35 to form a sealing layer. During maintenance, the grease injection port 37 of the flat duckbill-shaped grease injection gun 38 is inserted into the bottom of the fixed brush head 32 at the tail of the shield. Grease is injected into the tail of the shield through the high-pressure ball valve 39 on the flat duckbill-shaped grease injection gun 38. The handle 40 on the flat duckbill-shaped grease injection gun 38 is used to assist in the operation, achieving efficient sealing at the tail of the shield and improving the durability and reliability of the tail seal.

[0041] Step Six: Follow-up Secondary Grouting Construction: When the tunnel segment is inside the shield shell of the tunnel boring machine (TBM), holes are drilled at the top of the segment and ball valves are installed, with synchronous grouting ports 41 equipped on the ball valves. During segment assembly, adjacent segments are fastened together by segment bolts 42 to form a complete ring structure. In the three segments about to exit the shield shell, the synchronous grouting ports 41 on the first and second ring segments are connected to synchronous grouting pipes, and the synchronous grouting ports 41 on the third ring segment are connected to water glass pump pipes. During TBM excavation, the ball valves on the segments are opened: cement mortar is injected into the synchronous grouting ports 41 of the first and second ring segments through the synchronous grouting pipes, and water glass slurry is injected into the synchronous grouting ports 41 of the third ring segment through the water glass pump pipes. The two slurries mix and harden behind the segments. After grouting is completed, the ball valves are closed, and the pipes are disassembled and cleaned. After the tunnel segment exits the tail of the tunnel boring machine, if shrinkage or voids are detected in the synchronous grouting slurry during monitoring, secondary grouting is initiated. During secondary grouting, the follow-up grouting pipe 44 is connected to the synchronous grouting port 41 on the tunnel segment, and grouting is supplemented through the follow-up grouting pipe 44. After grouting is completed, the injection of water glass should be stopped first, followed by the injection of cement mortar, to reduce grout leakage.

[0042] Example 2: The semi-circular grouting shield tunnel in the deep silty soil strata was constructed using the aforementioned construction method for semi-circular grouting shield tunnels in the deep silty soil strata.

[0043] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls under the protection of this invention.

Claims

1. A construction method for a semi-circular grouting shield tunnel in deep silty soil strata, characterized in that, Includes the following steps: Step 1: Grouting reinforcement construction of the semi-ring inside the tunnel: In view of the problem of insufficient space in the starting shaft, a semi-ring starting method is adopted; firstly, a semi-ring assembled pipe segment (1) with a channel steel pad (3) is laid in the lower part of the starting space of the inner wall (2) of the shield tail; at the same time, a reinforcing ring beam (5) is set on the outside of the assembled full ring assembled pipe segment (4), and then concrete is poured into the bottom of the semi-ring assembled pipe segment (1) to complete the grouting reinforcement of the area of ​​the semi-ring assembled pipe segment (1); Step 2: Two-component grouting and mixing construction; Step 3, Intensive Secondary Grouting Construction: The grouting trolley (18) is moved to the grouting operation point inside the tunnel to carry out grouting operations; the grouting trolley (18) integrates a mixer (23) and a grouting pump (24). Cement slurry and water glass are introduced into the mixer (23) through the cement slurry inlet (19) and the water glass inlet (22) respectively. The two slurries are mixed evenly by the mixer (23) to obtain a mixed slurry; the flow rate of the slurry is adjusted by the control valves (21) on the cement slurry inlet (19) and the water glass inlet (22). The feed pressure is monitored in real time by the pressure gauge (20), and then the mixed slurry is transported to the grouting area by the grouting pump (24); Step 4: Rapid drilling construction of deep hole grouting: The outer casing (25) is pre-embedded in the grouting construction area. During grouting, the grouting rod (29) with rubber thread (28) is inserted into the outer casing (25). Grout is delivered through the grouting rod (29). The check valve (30) at the front end of the grouting rod (29) is used to prevent grout backflow. After grouting is completed, the water-swellable coil (26) set on the outside of the grouting rod (29) expands when exposed to water, so that the water-swellable coil (26) is tightly fitted with the inner wall of the outer casing (25) to form a seal. The screw cap (27) is tightened to seal the lower end of the outer casing (25). Step 5: Tunnel Boring Machine Tail Sealing Construction; Step 6: Follow-up secondary grouting construction.

2. The construction method for a semi-circular grouting shield tunnel in deep silty soil strata according to claim 1, characterized in that, In step one, the first I-beam (7) and the second I-beam (8) are connected by an arc-shaped steel plate (6) to form a segment support structure. The whole ring assembled segment (4) is placed on the segment support structure, and the whole ring assembled segment (4) is supported by the segment support structure.

3. The construction method for a semi-circular grouting shield tunnel in deep silty soil strata according to claim 1, characterized in that, In step two, water glass and tap water are stirred by an automatic stirring tank. The automatic stirring tank includes a cylinder, and a stirring rod is installed at the shaft of the cylinder. The stirring rod is composed of a shaft and a stirring tank blade (11). A stirring tank motor (15) is fixedly installed at the top edge of the cylinder. A first gear is installed at the motor shaft end of the stirring tank motor (15). The first gear meshes with a second gear set at the upper end of the stirring rod to form a stirring tank gear set (10). When the stirring tank motor (15) rotates, it drives the stirring rod to rotate through the stirring tank gear set (10). A slurry outlet (17) is opened at the bottom of the cylinder, and two independent slurry inlets are set at the top of the cylinder. The two slurry inlets at the top of the cylinder are tap water inlet (12) and water glass inlet (13), which are used for the separate injection of different slurries.

4. The construction method for a semi-circular grouting shield tunnel in deep silty soil strata according to claim 3, characterized in that, In step two, during the two-liquid grouting and mixing construction, the mixing tank motor (15) drives the mixing tank gear set (10) and drives the mixing tank fan blade (11) to rotate; tap water is introduced into the cylinder of the automatic mixing tank through the tap water inlet (12), and water glass is introduced into the cylinder of the automatic mixing tank through the water glass inlet (13). The tap water and water glass are quickly mixed by the mixing tank fan blade (11) in the cylinder to obtain a mixed slurry; the mixed slurry obtained by mixing is injected into the grouting area; after the automatic mixing tank completes the mixing operation, the slurry outlet (17) is closed, and clean water is introduced into the cylinder through the tap water inlet (12). The mixing tank fan blade is used to stir at high speed and rinse the inner wall of the cylinder. After cleaning, the slurry outlet (17) is opened, and the sewage is discharged through the slurry outlet (17).

5. The construction method for a semi-circular grouting shield tunnel in deep silty soil strata according to claim 1, characterized in that, The specific method of step five is as follows: At the tail of the shield machine, grout (34) is delivered through the grouting pipe (31), and impurities are cleaned by the fixed brush head (32) and wire brush (36) set at the tail of the shield. Grease is filled into the oil-filled gap ring (33) through the oil injection pipe (35) to form a sealing layer. During maintenance, the grease injection port (37) of the flat duckbill grease gun (38) is inserted into the bottom of the fixed brush head (32) at the tail of the shield, and grease is injected into the tail of the shield through the high pressure ball valve (39) on the flat duckbill grease gun (38).

6. The construction method for a semi-circular grouting shield tunnel in deep silty soil strata according to claim 5, characterized in that, The wire brush (36) at the tail of the shield consists of two steel plates, one above the other, and a wire sandwiched between the two steel plates.

7. The construction method for a semi-circular grouting shield tunnel in deep silty soil strata according to claim 5, characterized in that, The specific method for step six is ​​as follows: When the segment is inside the shield shell of the tunnel boring machine, a hole is opened at the top of the segment and a ball valve is installed, and a synchronous grouting port (41) is equipped on the ball valve; when the segments are assembled, adjacent segments are fastened together by segment bolts (42) to form a complete ring structure; in the three segments that are about to exit the shield shell, the synchronous grouting ports (41) on the first and second ring segments are connected to the synchronous grouting pipe, and the synchronous grouting port (41) on the third ring segment is connected to the water glass pump pipe; when the shield is excavated, the ball valve on the segment is opened: the synchronous grouting pipe injects cement mortar into the synchronous grouting ports (41) of the first and second ring segments, and the water glass pump pipe fills the synchronous grouting port (41) of the third ring segment with water glass slurry. The two slurries are mixed and hardened behind the segment; when the segment exits the shield tail of the tunnel boring machine, if shrinkage or voids are found in the synchronous grouting slurry during the monitoring process, secondary grouting is started.

8. The construction method for a semi-circular grouting shield tunnel in deep silty soil strata according to claim 7, characterized in that, During secondary grouting, the follow-up grouting pipe (44) is connected to the synchronous grouting port (41) on the segment, and grouting is carried out through the follow-up grouting pipe (44).

9. A semi-circular grouting shield tunnel in deep silty soil strata and its construction method, which is constructed by the construction method of the semi-circular grouting shield tunnel in deep silty soil strata as described in any one of claims 1-8.

Images