Seabed soft stratum slurry shield machine dismantling face sealing and reinforcing construction method
By using rigid connections between anti-reverse steel plates and pre-embedded steel plates in the shield shell and segments during shield tunneling, and displacement grouting with cement-water glass dual-liquid grout, combined with layered concrete sealing, the risks of leakage and detachment under high water pressure before shield dismantling in soft seabed strata were solved, achieving full closure and permanent sealing of the shield tail gap, thus improving construction safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA RAILWAY TUNNEL GROUP CO LTD
- Filing Date
- 2026-02-27
- Publication Date
- 2026-06-05
AI Technical Summary
In the construction of submarine tunnels, existing reinforcement methods pose risks of segment detachment, shield back-pushing, and water and sand inrush in soft seabed strata with high water pressure and strong permeability. Furthermore, conventional grouting and concrete sealing are not effective and it is difficult to form a reliable and dense sealing body.
The anti-retrograde steel plate is fully welded to the shield shell and the pre-embedded steel plates of the segments to form a rigid self-locking anti-retrograde structure. Combined with the displacement grouting of cement-water glass double liquid grout, a sealing system is formed through radial grouting of the shield body and grouting of the mud-water chamber. Plain concrete and reinforced concrete sealing walls are poured in layers to ensure that the shield tail gap is fully sealed and permanently plugged.
It achieves effective transmission of shield thrust and complete sealing of the shield tail gap, ensuring the compactness of grouting and the permanence of sealing, reducing the risk of leakage during dismantling, and improving construction safety and reliability.
Smart Images
Figure CN122148330A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of tunnel construction technology, specifically relating to a method for pre-reinforcement construction of shield tunneling machines in soft seabed strata with high water pressure and strong permeability. Background Technology
[0002] In the shield tunneling of undersea tunnels, the tunnel lining segments, shield tail, and tunnel face must be reinforced and sealed before dismantling the tunnel boring machine (TBM) inside the tunnel to prevent segment detachment, TBM back-pushing, and water / sand inrush accidents caused by high water pressure. Existing reinforcement methods typically include: grouting to form a water-sealing ring after constructing the segment wall at the TBM's arrival section; using channel steel or structural steel to tighten the segments to prevent back-pushing; filling the shield tail gap with grout; injecting cement slurry or mortar into the slurry chamber to seal the tunnel face; and pouring a concrete sealing wall after dismantling.
[0003] However, the conventional construction methods described above have the following drawbacks in soft, high-water-pressure seabed strata: First, when the channel steel is used to tighten the tunnel segments, the channel steel is prone to torsional deformation due to circumferential stress and cannot completely seal the annular gap between the shield tail and the tunnel segments. Under high water pressure, the tunnel segments may still fall off and the tunnel boring machine may be pushed back, making the dismantling process extremely risky. Second, in highly permeable strata, the grouting slurry is easily lost with seawater, and conventional single grouting is difficult to form a dense seal, resulting in frequent leakage at the tunnel face and shield tail. Third, conventional concrete sealing walls rely solely on the weight of the concrete and its bond with the surrounding rock, without reliable anchoring to the tunnel segments. Under repeated high water pressure, the joints are prone to cracking, and in soft soil strata, formwork is difficult to erect. The top of the sealing wall often forms cavities due to concrete shrinkage and gravity settlement, becoming permanent leakage channels. Therefore, there is an urgent need for a pre-reinforcement construction method specifically designed for soft seabed strata that can systematically solve the above problems and has quantifiable acceptance standards before tunnel boring machine dismantling.
[0004] The information disclosed in this background section is intended only to enhance the understanding of the background technology of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention
[0005] In view of at least one of the above technical problems, this disclosure provides a method for sealing and reinforcing the tunnel face of a slurry shield tunneling machine before dismantling in soft seabed strata, aiming to solve the problems of high water pressure back-pushing, loss of grout due to strong water permeability, cracking of soft soil sealing, and uncontrollable risks of dismantling.
[0006] According to one aspect of this disclosure, a method for sealing and reinforcing the tunnel face of a slurry shield tunneling machine before dismantling in soft seabed strata is provided, comprising the following steps: S1. Re-measurement control network; S2. Special lining section excavation, with pre-embedded arc steel plates in the segments; S3. Confirm downtime; S4. Construct a water-sealing ring and grout behind the pipe segment wall; S5. The anti-reverse steel plate is welded to the pre-embedded steel plate and the shield shell, and an arc-shaped sealing steel plate is welded between adjacent anti-reverse steel plates to close the shield tail gap. S6. Radial grouting of the shield body; grouting after washing the mud and water chamber, with an external grout discharge pipeline at the top to maintain pressure balance inside the chamber during grouting; S7. After acceptance according to the three major standards of reliable limit, leak-proof sealing, and environmental safety, the machine is disassembled in sections. S8. Pour plain concrete in layers; pour reinforced concrete sealing wall and anchor it with steel plates embedded in the pipe segments; leave grouting holes at the top of the wall and fill and seal the holes with grout after curing.
[0007] According to one aspect of this disclosure, the anti-reverse steel plates described in S5 are arranged at uniform intervals along the circumferential direction of the segment and are fully welded to the pre-embedded steel plates and the shield shell with double-sided bevels; after welding, non-destructive testing of the weld is performed; and after welding the arc-shaped sealing steel plates, a sealing test is performed.
[0008] According to one aspect of this disclosure, the grouting described in S4 and S6 uses a cement-water glass dual-liquid grout; in S4, the water sealing ring continuously seals 10 to 15 rings.
[0009] According to one aspect of this disclosure, the slurry chamber grouting in S6 includes: S6.1. Wash the silo until there is no obvious residue on the screen plate; S6.2. Mixing synchronous grouting mortar; S6.3. Grouting in layers from bottom to top; S6.4. The top ball valve is connected to an external slurry discharge pipeline for bypass circulation and mud replacement; S6.5. Voltage stabilization maintenance; S6.6. Check the filling density by opening the ball valve layer by layer; S6.7. An observation hole is opened in front of the screw press for verification.
[0010] According to one aspect of this disclosure, the pre-disassembly acceptance criteria described in S7 include: the weld seam of the anti-reverse steel plate is qualified, and the anti-reverse steel plate and the arc-shaped sealing steel plate are free from deformation and loosening; the shield tail gap sealing test is qualified, there is no water gushing from any hole of the sealing ring, there is no water gushing from the ball valve of the mud and water chamber and mortar overflows from the top, and there is no water in the observation hole in front of the screw compressor; ventilation and gas monitoring meet the standards, and the segments are free from displacement and cracking.
[0011] According to one aspect of this disclosure, the shield body described in S8 is filled with layered cast plain concrete, with roughening between layers, compaction by vibration, and anchor bolts pre-embedded at the bottom of each layer.
[0012] According to one aspect of this disclosure, the reinforced concrete sealing wall described in S8 is equipped with a double-layer steel mesh and tie bars; the formwork is fixed by diagonal tie rods, the bottom tie rod is welded to the shield body, and the upper tie rod is anchored to the pre-embedded anchor rods; the sealing wall anchor bars are welded to the pre-embedded steel plates of the pipe segments; and grouting holes and venting holes are reserved at the top of the wall.
[0013] According to one aspect of this disclosure, after the sealing wall in S8 is cured, the density is tested by pre-reserved grouting holes, and reinforcing material is injected into the voids or leaks, and the holes are sealed after reinforcement.
[0014] According to one aspect of this disclosure, each segment of the special lining section described in S2 is provided with multiple grouting holes, and multiple grouting points can be selected for each ring.
[0015] According to one aspect of this disclosure, after each section of the segmented dismantling machine described in S7 is dismantled, a temporary sealing plate is used to cover the exposed section, and the plate seam is provided with a water-swellable sealant.
[0016] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: 1. Rigid self-locking anti-retrograde structure: The anti-retrograde steel plate is fully welded to the shield shell and the pre-embedded steel plate of the segment, forming an axial rigid force transmission path. The arc-shaped sealing steel plate welded between adjacent steel plates realizes the full closure of the shield tail gap, and directly transmits the shield thrust to the segment structure.
[0017] 2. Displacement grouting principle: The interface deterioration layer is removed by washing the chamber, and the mud in the chamber is replaced layer by layer from bottom to top. The top bypass circulation maintains pressure balance. The filling is driven by grouting pressure rather than gravity, so as to achieve full-section dense sealing of the working face.
[0018] 3. Anchored permanent sealing: The sealing wall is welded and anchored to the pre-embedded steel plate of the pipe segment, so that the temporary structure and the permanent structure form an integral load-bearing system; the formwork is inclined and anchored to utilize the self-supporting capacity of the poured concrete, solving the problem of formwork support in soft soil layers; the grouting hole reserved at the top of the wall enables secondary grouting after pouring, eliminating defects at the top of the sealing body. Attached Figure Description
[0019] Figure 1 This is a flowchart illustrating a construction method for sealing and reinforcing the tunnel face before dismantling a slurry shield tunneling machine in a soft seabed stratum, as described in one embodiment of this application.
[0020] Figure 2 This is a schematic diagram of the pre-embedded arc-shaped steel plate at the end of the pipe segment in one embodiment of this application.
[0021] Figure 3 This is a schematic diagram of the anti-retraction steel plate sealing in one embodiment of this application. Figure 1 .
[0022] Figure 4 This is a schematic diagram of shield tail gap sealing in one embodiment of this application.
[0023] Figure 5 This is a partial enlarged view of the shield tail gap sealing in one embodiment of this application.
[0024] Figure 6 This is a schematic diagram of the concrete pouring process for the shield tunneling machine sealing in one embodiment of this application.
[0025] Figure 7 This is a load transfer diagram in one embodiment of this application.
[0026] In the above figures, 1 is the tunnel segment, 2 is the pre-embedded arc-shaped steel plate, 3 is the shield shell, 4 is the anti-retreat steel plate, 5 is the sealing steel plate, 6 is the sealing device, 61 is the temporary support truss, 62 is the template, 63 is the bolt, 64 is the round steel, 7 is the filling layer, 71 is the shield tail water sealing ring, 72 is the shield body water sealing ring, 73 is the cutterhead grouting filling layer, and 8 is the working face water pressure. Detailed Implementation
[0027] In the description of this application, it should be understood that the terms "upper," "lower," "front," "rear," "top," "bottom," "inner," "outer," "vertical," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and for 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, they should not be construed as limitations on this application. The terms "first," "second," etc., used in this application are used to distinguish the described objects and do not have any sequential or technical meaning. Unless otherwise specified, the terms "connection" and "linkage" used in this application include both direct and indirect connections (linkages).
[0028] Unless otherwise specified, all devices and other components mentioned in the following examples are commercially available products.
[0029] Example:
[0030] This example discloses a method for sealing and reinforcing the tunnel face of a slurry shield tunneling machine before dismantling in soft seabed strata. (See also...) Figure 1 The complete construction process of this method is as follows: S1. Re-measurement of the Measurement Control Network. Before the tunnel boring machine (TBM) arrives, a total station and level are used to re-measure the horizontal and vertical control networks inside the tunnel. The coordinates of the traverse points and the elevations of the leveling points are re-measured and connected with the coordinates of the tunnel portal center to ensure that the TBM's stopping posture deviates from the design axis within the allowable range. By re-measuring the measurement control network, a reliable measurement benchmark is provided for subsequent confirmation of the stopping mileage and precise stopping of the TBM, avoiding the impact of measurement errors on the TBM cutterhead hitting the tunnel portal or excessive deviation in the stopping position, which would affect subsequent reinforcement procedures.
[0031] S2. Excavation of the Special Lined Section. After the production of the special lining section segment rings is completed, the excavation of the special lining section continues. In this embodiment, the special lining section uses steel segments. Each standard block and adjacent block is equipped with 3 grouting holes, for a total of 16 grouting points (corresponding to 16 sets of hydraulic cylinder positions) for the entire ring, providing sufficient channels for subsequent secondary grouting and inspection behind the segment wall. A full-length arc-shaped steel plate is pre-embedded on the jack-facing surface of the last ring of concrete segments for subsequent welding of the anti-retrograde steel plate. During the excavation process, the thrust, torque, and slurry pressure are strictly controlled to ensure smooth passage. The pre-embedded arc-shaped steel plate provides a reliable welding base for the segment anti-retrograde device; the multiple grouting hole design facilitates grouting and effect inspection; the steel segments have high strength and corrosion resistance, making them suitable for highly corrosive seabed environments.
[0032] S3. Confirm the shutdown mileage. The tunnel boring machine (TBM) stops when the cutterhead reaches the designed shutdown mileage. Based on the re-measurement results in S1, the positional relationship between the cutterhead and the tunnel portal is verified to confirm the shutdown location. This step ensures the reasonableness of the distance between the TBM cutterhead and the tunnel portal, preventing the cutterhead from colliding with the portal and reserving sufficient space for subsequent slurry filling, thus ensuring the sealing effect at the tunnel face.
[0033] S4. Construct the sealing ring. Inject cement-water glass dual-liquid grout into the rear wall of the segment through the radial grouting holes. In this embodiment, P.O42.5 grade cement is used, with a water glass concentration of (35Be'-38Be'), a volume ratio of cement:water glass = 1:1, a water-cement ratio of 0.8:1, and the grouting pressure is controlled at 0.3-0.5 MPa. After the grout production is completed, a sample is retained to test the setting time and strength. If the quality does not meet the standards, the grout in the chamber is replaced, and production is restarted. Continuously seal 10-15 rings, and after stabilizing the pressure in each hole until the single-hole grout absorption rate is <0.1L / min, close the ball valve. At the same time as grouting, tighten all bolts on the last 15 rings of the segment. The cement-water glass double-liquid grout has a short setting time (tens of seconds to several minutes) and high early strength, and can quickly form a water-stop curtain under high water pressure and dynamic water conditions, effectively reducing grout loss; continuous multi-ring water-sealing rings form a closed seepage-proof ring, blocking the longitudinal seepage channel behind the pipe segment wall; bolt tightening ensures the integrity of the pipe segment and prevents later displacement.
[0034] S5. Welding of segment anti-retrograde device. For example... Figure 2 , 3 As shown, anti-reverse steel plates are welded onto the arc-shaped steel plates pre-embedded on the jacking surface of the last ring of concrete segments. The anti-reverse steel plates are made of Q235B steel, 30mm thick, and 60 plates are evenly arranged at 6° intervals along the circumference of the segment. Each anti-reverse steel plate has an effective welding length of 216.4mm on the left side and 400mm on the top side, using a double-sided 14mm bevel full weld with a weld height of 14mm. Before welding, the pre-embedded steel plates and the contact surfaces of the shield shell are cleaned of oil and rust. Trial welding is performed first to determine parameters. After formal welding, each weld is subjected to 100% ultrasonic testing. The welds should be free of defects such as porosity, slag inclusions, and incomplete fusion, with a 100% pass rate.
[0035] like Figure 4 , 5 As shown, an arc-shaped sealing steel plate (Q235B, 16mm thick) is welded to the gap between adjacent anti-reverse steel plates, completely covering the annular gap between the shield tail and the tunnel segment. After welding, a 0.4MPa air pressure test is conducted, maintaining the pressure for 5 minutes with no pressure drop and no weld leakage. After all welding is completed, the propulsion cylinders are retracted sequentially to release the thrust. The anti-reverse steel plate, the embedded steel plate, and the shield shell form a rigid, fully welded connection, directly transferring the potential back thrust of the tunnel boring machine to the tunnel segment structure, completely solving the problems of high-water-pressure shield back thrust and segment detachment; the arc-shaped sealing steel plate completely seals the shield tail gap, eliminating the defect of traditional channel steel tensioning failing to seal; dual acceptance through non-destructive testing and sealing tests of the weld ensures the safety and reliability of the limit system.
[0036] S6. Shield tail compaction grouting and slurry chamber grouting and sealing. This includes the following steps: Tail compaction grouting: After welding arc-shaped sealing steel plates between the anti-retreat steel plates, the annular gap between the tail of the shield and the segments is filled. Cement-water glass double liquid grout with the same mix ratio as S4 is injected through the radial grouting holes of the shield body at a grouting pressure of 0.4 MPa to form a water-sealing ring in the shield body, further blocking the seepage channels around the tail of the shield.
[0037] Grouting and sealing of mud and water chamber: S6.1 Washing the slurry tank until no obvious debris remains on the screen: Start the circulation system to circulate and clean the slurry tank. After 2 hours of circulation, no obvious debris remains on the hydrocyclone screen of the slurry station, and the debris and impurities inside the tank are completely removed. The washing process thoroughly removes any residual debris from the tank, creating interface conditions for direct bonding between the mortar and the formation.
[0038] S6.2 Mixing of synchronous grouting mortar: Synchronous grouting uses improved mortar, which is mixed according to the reasonable ratio of cement, sand, fly ash, bentonite and water to improve the adhesion and early strength of the grout; secondary grouting uses fast-setting water glass double-liquid grout to shorten the setting time and reduce grout loss.
[0039] S6.3 Layered grouting from bottom to top: Connect the grouting hose to the grouting port reserved at the 3 o'clock (low position) of the pressure-bearing partition of the mud-water chamber, start the grouting pump, and adopt the layered grouting method from bottom to top.
[0040] S6.4 Top ball valve connected to external slurry discharge pipeline for bypass circulation and slurry replacement: During grouting, a hose is connected to the slurry discharge pipeline outside the top ball valve, and the bypass circulation mode is activated to replace and discharge the slurry in the chamber, maintaining stable pressure within the chamber. The grouting pressure is gradually increased to 1.5 times the soil and water pressure and stabilized for 30 minutes. Grouting is sequentially switched to the 6 o'clock, 9 o'clock, and 12 o'clock (high position) reserved ports, and the grouting port is closed after continuous and dense mortar flows out of the ball valve at each location. Layered grouting from bottom to top avoids air retention at the top, ensuring dense filling of the entire cross-section; the top bypass circulation balances the pressure, using grouting pressure to drive replacement rather than relying on gravity, preventing sudden pressure rises and falls during grouting that could cause ground disturbance; the grouting pressure is actively controlled to 1.5 times the soil and water pressure, which is sufficient to overcome high water pressure without damaging the strata.
[0041] S6.5 Stabilizing Curing: After grouting is completed, allow the mortar to stand for 3 days until it reaches the design strength.
[0042] S6.6 Checking the compactness of the grout by opening the ball valves layer by layer: After the curing period, the ball valves at different heights are opened sequentially from bottom to top to check for leakage and the compactness of the mortar filling. In this embodiment, there was no water flow after the bottom and middle ball valves were opened, and dense mortar flowed out after the top ball valve was opened. There were no air bubbles or water flow, so the grouting was deemed qualified.
[0043] S6.7 Verification via observation hole before screw conveyor: Before dismantling the screw conveyor, open a Φ50mm observation hole in the segment in front of it to confirm that no water is flowing out. Double inspection via valve opening at each point and the observation hole before the screw conveyor makes the sealing effect visible and detectable, eliminating potential leakage risks. If leakage is found, an opening must be made at the top of the silo wall (with a ball valve welded before opening to prevent backflow) to check the filling density. Inject dual-liquid grout or polyurethane reinforcement through pre-set grouting holes until there is no leakage at all points.
[0044] The tunnel boring machine is dismantled in sections according to a preset sequence. Before the first section is dismantled, observation holes are opened in the segments to check the grouting sealing effect. If water inrush is found, emergency sealing materials are used to deal with it immediately. After each section of equipment is dismantled, the exposed shield section is covered with a temporary sealing plate, and the plate joints are sealed with water-swellable sealants.
[0045] Ventilation equipment is installed in the dismantling area to enhance air circulation and reduce ambient humidity, and gas detection equipment is installed to monitor the concentration of harmful gases in real time; oily wastewater generated during dismantling is collected and treated in special containers to avoid corroding the pipe segment sealing structure and equipment.
[0046] In the event of a sudden water inrush, immediately activate the emergency grouting system to inject fast-setting dual-liquid grout through pre-set grouting holes to quickly form a sealing curtain; activate emergency power supply equipment to ensure power supply to the grouting equipment and ensure timely emergency sealing under high water pressure.
[0047] S7. Pre-dismantling acceptance and tunnel boring machine (TBM) segment dismantling. Pre-dismantling acceptance includes the following three major systems of quantitative acceptance: (1) The limiting system is reliable.
[0048] The quality requirements for the welding of the anti-reverse steel plate are as follows: the weld seam passes non-destructive testing with a 100% pass rate, free from defects such as porosity, slag inclusions, and incomplete fusion; before welding, clean the debris from the pre-embedded steel plate of the tunnel segment and the contact surface of the shield shell, and perform trial welding according to the appropriate parameters before formal welding to ensure that the weld seam is smooth and free of sharp edges. The quality requirements for the limiting structure state are as follows: the anti-reverse steel plate is tightly fitted to the pre-embedded steel plate of the tunnel segment and the shield shell without loosening, is evenly distributed in the circumferential direction, and the rigid support system is well formed; through visual inspection and stress observation, there is no deformation or stress concentration, and it can completely replace the tensioning function of the tunnel segment to resist high water pressure thrust.
[0049] (2) The sealing system is leak-free.
[0050] In the shield tail gap sealing, the arc-shaped sealing steel plate completely covers the gap between the shield tail and the segment, and the plate seam is welded tightly; after welding, a water flushing test or air pressure test (the test pressure is adapted to the actual working conditions) is conducted, and there is no water seepage or sand leakage, and there are no abnormal leakage traces at the weld and the steel plate bonding area.
[0051] Regarding the water-sealing ring seal, after the radial grouting holes of the tunnel segments were opened, there was no obvious water inflow, no continuous water flow, and no sand particles were carried out. After the full ring grouting and secondary grouting were completed, all holes were closed, and no continuous leakage was observed through the observation holes. There was no continuous grout absorption phenomenon during the secondary grouting, proving that the water-sealing ring seal was effective. The seal was continuous and intact, without voids or cracks, and the grout was tightly bonded to the tunnel segments and the formation.
[0052] The requirements for grouting the sealing mortar in the mud-water silo are as follows: Use the bypass circulation mode to balance the pressure inside the silo. After the grouting pressure rises to 1.5 times the water and soil pressure, stabilize the pressure. During this period, open ball valves at different heights at fixed intervals to observe and ensure that the mortar fills evenly and replaces the original mud in the silo. After grouting, cure for no less than 3 days as required by the design, until the mortar reaches the design strength. Open the ball valves at different heights of the silo from bottom to top. There should be no water inflow or mud leakage. The top ball valve should overflow with dense, bubble-free mortar. If water leakage is found, a hole should be opened at the top of the silo wall (with a ball valve welded before opening to prevent backflow) to check the filling density. Inject two-component grout or polyurethane reinforcement through the pre-set grouting holes until there is no leakage at all points.
[0053] Before dismantling the screw conveyor, an inspection should be performed. An observation hole should be opened in front of the screw conveyor to confirm that there is no water flowing out and that the grouting sealing effect meets the standards before dismantling.
[0054] (3) Environmental and structural safety.
[0055] Working environment. Ventilation equipment was installed in the dismantling area, ensuring smooth airflow and maintaining humidity within a suitable range. Hazardous gas concentrations were monitored in real-time using portable detectors, and all results met safety limits. The dismantling area was equipped with axial flow fans, and portable detectors for hazardous gases (CH4, H2S, CO) were used for real-time monitoring. Concentrations were below the lower explosive limit and occupational exposure limits. The pipe segments showed no displacement or cracking, and the joint gaskets were intact.
[0056] Working face condition. Debris, oil, and laitance within the shield body and dismantling area have been cleaned, with no water accumulation and no slippery surface posing a risk of corrosion or affecting operational safety. Segmented dismantling and hoisting will be employed. After acceptance, the tunnel boring machine will be dismantled and hoisted in segments in the order of cutterhead—front shield—middle shield—tail shield. After each segment is dismantled, the exposed section will be immediately covered with temporary sealing plates, and water-swellable sealing strips will be applied to the plate seams. Oily wastewater from the dismantling area will be collected in dedicated containers to prevent contamination of the tunnel segments and sealing structures.
[0057] In terms of structural condition, the segments should be free from cracks and displacement, the joint sealing gaskets should be free from damage and detachment, and the circumferential and longitudinal joints should be tightly fitted without any signs of leakage; the shield body should be free from structural deformation and damage, the pressure-bearing diaphragms and chamber walls should be free from rust and leakage, and the key welds should be free from abnormalities.
[0058] This step establishes quantitative acceptance standards for the first time before the disassembly process, upgrading the disassembly permit from experience-based judgment to a technically verifiable and re-verifiable release point, significantly reducing the risk of water and sand inrush caused by blind disassembly; segmented sealing measures prevent leakage caused by excessive exposure time of cross-sections during the disassembly process.
[0059] S8. Construction of the shield body filling and sealing wall, as follows: Figure 6 As shown.
[0060] (1) Plain concrete filling: After dismantling, clean the inside of the shield body of accumulated slag, oil stains, and laitance. Pour C45 plain concrete in layers from the tail of the shield towards the cutterhead. Use an immersion vibrator in a row-and-column manner, with a vibration point spacing of 500mm. Insert the vibrator quickly and withdraw it slowly, vibrating each point for 20-30 seconds until the surface is covered with slurry and no air bubbles. Before pouring each layer, roughen the surface of the lower layer of concrete and clean the laitance and loose aggregate. After each layer is poured, pre-embed a section of anchor rod at the bottom. The anchor rod is made of 25mm round steel and serves as the anchor point for the tie rod of the lower formwork.
[0061] (2) Construction of reinforced concrete sealing wall: After the last layer of plain concrete is poured, formwork is erected 1.2m away from the shield tail. The formwork is made of plywood, with square timber secondary beams and steel pipe main beams. The formwork is fixed by multiple tie rods at an angle. The bottom tie rods are welded to the shield body, and the upper tie rods are anchored to the pre-embedded 25mm round steel. The sealing wall and the plain concrete filling are integrally formed. The last section of the sealing wall formwork is reserved with grouting holes. After the concrete is poured, the filling density is checked. Reinforcing materials are injected into the top voids or leakage areas using grouting equipment. After grouting, the reserved holes are permanently sealed, forming a triple protection of "layered filling + rigid sealing + grouting reinforcement".
[0062] The sealing wall is constructed of reinforced concrete, equipped with double-layer steel mesh and studded reinforcing bars arranged in a staggered pattern. The anchor bars are welded and anchored to the pre-embedded steel plates of the pipe segments. A C45 reinforced concrete sealing wall, 1.2m thick, is poured and integrally formed with the plain concrete infill layer. Grouting holes and vents are pre-reserved at the top of the formwork. Air is expelled through the vents during concrete pouring, and the concrete is vibrated to ensure compaction. The grouting holes are filled with polyurethane foam or other temporary sealing materials for protection. After the concrete pouring is complete, the pre-reserved grouting holes are opened to check the compactness of the concrete filling. If holes or water leakage are found behind the sealing wall, cement grout is used to fill the holes with cement grout. After filling, the pre-reserved grouting holes are permanently sealed.
[0063] (3) Grouting reinforcement after sealing the wall: After 14 days of concrete curing, the density of the sealed wall was tested using ultrasonic testing through the pre-reserved grouting holes. In this embodiment, no voids or water seepage were detected. To prevent shrinkage cracks, cement grout (water-cement ratio 0.5:1) was injected for reinforcement at a pressure of 0.2 MPa and a volume of approximately 0.3 m³. After reinforcement, the pre-reserved grouting holes were permanently sealed.
[0064] like Figure 7 As shown, the concrete was filled after dismantling the machine. The reinforcement of the tunnel segment wall and the shield body was carried out with double-liquid grout. The working face was reinforced with cement mortar. The reinforcement sequence was: tunnel segment water sealing ring, shield body water sealing ring, and cutterhead front sealing. Water pressure was transmitted from the rear to the working face. When the working face was finally reinforced, the water pressure in the chamber was discharged through the connecting pipe of the chamber top connecting valve to the grout discharge pipe.
[0065] A reinforced concrete sealing wall is used to fill the cavities of plain concrete, effectively blocking the leakage path of highly permeable strata. The sealing wall is welded to the pre-embedded steel plates of the tunnel segments with anchor bars, significantly improving the connection stability under high water pressure and avoiding the cracking problems of conventional sealing methods. Grouting holes and vent holes are reserved at the top of the wall. After pouring, the density is tested, and cement grout is injected to reinforce any voids or leakage areas, solving the problem of insufficient compaction at the top of soft soil strata. The plain concrete is filled in layers to ensure density, and the interlayer roughening ensures the bonding surface resistance. Shear capacity; pre-embedded anchor rods provide reliable tie points for subsequent sealing wall formwork; reinforced concrete sealing wall and pipe segment pre-embedded steel plates are welded and anchored to form an integral force system, avoiding joint cracking under high water pressure; formwork inclined anchoring technology utilizes the self-bearing capacity of the poured concrete to solve the problem of soft soil strata without solid foundation for formwork support; pre-reserved grouting holes at the top enable secondary grouting after pouring, completely eliminating void defects at the top of the sealing body caused by concrete settlement and shrinkage, achieving permanent sealing with "zero leakage".
[0066] Although some preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.
[0067] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application is also intended to include such modifications and variations.
Claims
1. A method for sealing and reinforcing the tunnel face before dismantling a slurry shield tunneling machine in soft seabed strata, characterized in that, Includes the following steps: S1. Re-measurement control network; S2. Special lining section excavation, with pre-embedded arc steel plates in the segments; S3. Confirm downtime; S4. Construct a water-sealing ring and grout behind the pipe segment wall; S5. The anti-reverse steel plate is welded to the pre-embedded steel plate and the shield shell, and an arc-shaped sealing steel plate is welded between adjacent anti-reverse steel plates to close the shield tail gap. S6. Radial grouting of the shield body; grouting after washing the mud and water chamber, with an external grout discharge pipeline at the top to maintain pressure balance inside the chamber during grouting; S7. After acceptance according to the three major standards of reliable limit, leak-proof sealing, and environmental safety, the machine is disassembled in sections. S8. Pour plain concrete in layers; pour reinforced concrete sealing wall and anchor it with steel plates embedded in the pipe segments; leave grouting holes at the top of the wall and fill and seal the holes with grout after curing.
2. The method according to claim 1, characterized in that, The anti-reverse steel plates described in S5 are evenly spaced along the circumference of the segment and are fully welded to the pre-embedded steel plates and shield shell with double-sided bevels; after welding, non-destructive testing of the weld is carried out; after welding the arc-shaped sealing steel plates, a sealing test is carried out.
3. The method according to claim 1, characterized in that, The grouting described in S4 and S6 uses cement-water glass dual-liquid grout; in S4, the water sealing ring continuously seals 10 to 15 rings.
4. The method according to claim 1, characterized in that, The grouting of the mud-water chamber described in S6 includes: S6.
1. Wash the silo until there is no obvious residue on the screen plate; S6.
2. Mixing synchronous grouting mortar; S6.
3. Grouting in layers from bottom to top; S6.
4. The top ball valve is connected to an external slurry discharge pipeline for bypass circulation and mud replacement; S6.
5. Voltage stabilization maintenance; S6.
6. Check the filling density by opening the ball valve layer by layer; S6.
7. An observation hole is opened in front of the screw press for verification.
5. The method according to claim 1, characterized in that, The pre-disassembly acceptance standards described in S7 include: the weld seam of the anti-reverse steel plate is qualified, and the anti-reverse steel plate and the arc-shaped sealing steel plate are free from deformation and loosening; the shield tail gap sealing test is qualified, there is no water gushing from any hole of the water sealing ring, there is no water gushing from the ball valve of the mud and water chamber and there is mortar overflowing from the top, and there is no water in the observation hole in front of the screw compressor; ventilation and gas monitoring meet the standards, and there is no displacement or cracking of the segments.
6. The method according to claim 1, characterized in that, The shield body described in S8 is filled with layered plain concrete, with roughening between layers, compaction by vibration, and anchor bolts pre-embedded at the bottom of each layer.
7. The method according to claim 1, characterized in that, The reinforced concrete sealing wall described in S8 is equipped with a double-layer steel mesh and tie bars; the formwork is fixed by diagonal tie rods, the bottom tie rod is welded to the shield body, and the upper tie rod is anchored to the pre-embedded anchor rods; the sealing wall anchor bars are welded to the pre-embedded steel plates of the pipe segments; grouting holes and venting holes are reserved at the top of the wall.
8. The method according to claim 1, characterized in that, After the sealing wall in S8 is cured, the density is tested by pre-reserved grouting holes. Reinforcing material is injected into the voids or leaks, and the holes are sealed after reinforcement.
9. The method according to claim 1, characterized in that, The special lining segment described in S2 has multiple grouting holes for each segment, and multiple grouting points can be selected for each ring.
10. The method according to claim 1, characterized in that, As described in S7, after each section of the machine is dismantled, a temporary sealing plate is used to cover the exposed section, and water-swellable seals are installed at the joints of the plates.