Method for repairing a cutter head during tunneling with a shield machine

Abstract

The application discloses a cutter head repairing method in a tunneling process of a shield machine, and belongs to the technical field of shield construction, and solves the problems that an existing method does not construct an active stability system for a working face and a soil bin environment, and lacks accurate detection and regulation means for large-scale poses of a cutter head, the method comprising the following steps: dividing a shield soil bin and a working face area into multiple operation layers, layer-by-layer cleaning of the working face and grading fixation of the cutter head, synchronous control of multiple horizontal displacement oil cylinders for adjusting the pose of the cutter head by a hydraulic pump station, taking out broken wires by using a welding auxiliary pulling or a counterbore tapping process, resuming tunneling after completing a main drive pressure maintaining test and cutter head operation verification, and in-situ repairing of the shield machine after a major structural failure such as cutter head falling in a tunneling process, without the need of withdrawing the shield machine from the tunnel or adding a ground vertical shaft, and meanwhile, secondary disturbance to surrounding strata is avoided, thereby providing systematic technical support for safe and continuous pushing of shield construction under complex geological conditions.

Description

Technical Field

[0001] This invention belongs to the field of tunnel boring machine (TBM) construction technology, specifically relating to a method for repairing the cutterhead during the tunneling process of a TBM. Background Technology

[0002] With the continuous advancement of urban rail transit and underground space development and construction, shield tunneling has become the mainstream construction method for urban subways, integrated utility tunnels, and river-crossing tunnels. Shield machines excavate long distances in complex and ever-changing geological environments. As the core component for direct rock-breaking excavation, the cutterhead endures high-intensity, high-frequency mechanical loads and geological wear for a long time. Its structural integrity and operational reliability are directly related to the safety, efficiency, and cost of the entire shield construction.

[0003] During shield tunneling, cutterhead system failures mainly manifest in the following ways: First, when tunneling in cohesive soil layers, the cutterhead panel and cutters are easily covered by clay, forming mud cakes or clogging, leading to abnormally high cutterhead torque and a sharp drop in tunneling efficiency. Second, when traversing unfavorable strata such as hard rock, boulders, and dense gravel, cutter wear, breakage, and even detachment become prominent issues, which can severely damage the cutterhead structure. Third, in composite strata such as soft upper layers and hard lower layers, the cutterhead bears non-uniform loads, which can easily lead to serious mechanical failures such as fatigue fracture of cutterhead connecting bolts, failure of cutterhead segment connections, and damage to drive disc bolts. In extreme cases, even cutterhead detachment accidents may occur.

[0004] Currently, conventional methods for handling shield tunneling machine cutterhead failures mainly include: performing pressurized opening inspection and partial cutter replacement after shutdown; conducting cutterhead repairs at ground shafts or connecting passages within the tunnel; and removing the entire shield machine from the tunnel and returning it to the factory for maintenance. However, all of these methods have significant limitations: pressurized opening operations can only address localized problems at the cutter level and cannot resolve damage to the main cutterhead structure; setting up shafts or connecting passages for repairs requires additional engineering measures, resulting in long construction periods and high costs; and removing the shield machine from the tunnel and returning it to the factory for maintenance involves complex procedures such as equipment dismantling, hoisting and transportation, and travel between the tunnel and the outside, which not only leads to long-term project shutdowns but also incurs huge secondary entry costs. Furthermore, the movement of the shield machine can easily cause secondary disturbances to the surrounding strata, leading to safety risks such as ground subsidence and deformation of nearby buildings and structures.

[0005] Chinese patent CN116021228B discloses a method for repairing the central area of ​​a tunnel boring machine (TBM) cutterhead. The method includes: repair preparation; repairing the water injection nozzles and mud / foam injection holes; repairing welded cutting tools; repairing the replaceable scraper holder; and repairing the cutter box and panel. The beneficial effect of this invention is that the TBM cutterhead central area repair method, through repair preparation, repair of the water injection nozzles, mud / foam injection holes, repair of welded cutting tools, repair of the scraper holder, and repair of the cutter box and panel, allows for the repair of the central area of ​​the TBM cutterhead inside the tunnel, avoiding the need for surface excavation and saving costs. However, existing methods lack the ability to handle overall structural failures of the cutterhead (especially failures in the connection between the cutterhead and the drive disc, and overall cutterhead detachment). Furthermore, an active stabilization system for the tunnel face and soil chamber environment has not been established. When performing repair work in high-risk strata, it is difficult to effectively block external water and soil pressure, easily inducing tunnel face instability or the risk of water and sand inrush. Simultaneously, there is a lack of precise detection and control methods for the large-scale position and orientation of the cutterhead. Relying solely on manual experience for welding repair makes it difficult to guarantee the alignment and installation accuracy of the repaired cutterhead, failing to meet the high standard requirement of overall cutterhead reset. To address these issues, we propose a cutterhead repair method during tunnel boring machine (TBM) excavation. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for repairing the cutterhead during tunnel boring machine (TBM) excavation. This method solves the problem of existing methods lacking the ability to handle structural failures of the cutterhead as a whole (especially failures in the connection between the cutterhead and the drive disc, and overall cutterhead detachment). Furthermore, it lacks an active stabilization system for the tunnel face and soil chamber environment, making it difficult to effectively block external water and soil pressure when performing repair operations in high-risk strata, easily inducing tunnel face instability or the risk of water and sand inrush. Simultaneously, it lacks precise detection and control methods for the large-scale position and orientation of the cutterhead, relying solely on manual experience for welding repair, which makes it difficult to guarantee the alignment and installation accuracy of the repaired cutterhead, failing to meet the high standard requirement of overall cutterhead repositioning.

[0007] This invention is implemented as follows: a method for repairing the cutterhead during tunnel boring machine (TBM) excavation, the method comprising: The tunnel boring machine's tunneling parameters are acquired in real time, and it is determined whether the tunneling parameters exceed the preset abnormal parameter threshold. If the tunneling parameters exceed the preset abnormal parameter threshold, the tunnel boring machine is stopped for pre-processing. For the ground reinforcement treatment at the location where the tunnel boring machine stops, a drilled pile reinforcement system is constructed in front of and around the cutterhead; Based on the top-down, segmented advancement rule, the shield tunnel soil chamber and face area are divided into multiple working layers. The face is cleaned in layers and the cutterhead is fixed in stages. Temporary fixing steel and support platform are welded between the cutterhead and the shield tunnel soil chamber wall. Remove the temporary fixed steel section, install multiple horizontal pushing cylinders on the support platform, and use the hydraulic pump station to synchronously control the multiple horizontal pushing cylinders to adjust the attitude of the cutter head; Open an operating through hole at the corresponding position on the cutter head flange, rotate the drive disc to align the broken bolt with the through hole, and remove the broken wire by welding-assisted extraction or countersinking and tapping process, and simultaneously replace and pre-tighten the new bolt. Precisely align the cutterhead flange with the drive disc flange, install the locating pins and connecting bolts and tighten them to the designed torque. After completing the main drive pressure holding test and cutterhead operation verification, resume tunneling.

[0008] Preferably, the method for constructing a bored pile reinforcement system in front of and around the cutterhead includes: Multiple water-stopping rings were installed at the circumferential ring segments where the tunnel boring machine was stopped, and low-strength excavable filling mortar was filled into the tunnel soil chamber. A borehole pile array is laid in front of and above the tunnel boring machine (TBM), and the TBM is reinforced by the borehole pile array. The borehole pile array includes type A, type B, type C, type D, and type E borehole piles. Among them, type A borehole piles include A1-A8, type B borehole piles include B1-B17, type C borehole piles include C1-C8, and type D borehole piles include D1-D8. The diameter of the borehole piles is 1m. After the pile foundation in the empty pile area is completed, C20 concrete is backfilled. A steel casing is buried in the stratum area above the type E borehole piles. The bottom of the steel casing is embedded in the stable bearing layer for more than 1 meter, and the top of the steel casing is higher than the stratum above it for more than 1 meter. A triangular stiffening steel plate is welded to the outside of the steel casing. The stiffening steel plate has a top 5-8cm, a bottom 12-18cm, a height of 8-12cm, and a thickness of 1.5-2.5cm. The bottom of the B1-B17 bored piles is reinforced with an 11m long glass fiber reinforced steel cage. The C1-C8 and D1-D8 bored piles are reinforced with additional steel cages on the outside. The steel bars of the C1-C8 and D1-D8 bored piles are anchored into the upper part to form an extension plate, which is then placed on the B-type bored piles.

[0009] Preferably, the excavable filling mortar comprises the following raw materials in parts by weight: 30-50 parts cement, 300-400 parts fly ash, 450-550 parts yellow sand, 120-150 parts bentonite, 8-15 parts expanding agent, 1-10 parts sodium gluconate, 2-4 parts crack-resistant fiber, 1-5 parts citric acid, and 450-500 parts mixing water. Among them, the crack-resistant fiber is a blend of polypropylene fiber and PVA fiber, with a mass ratio of polypropylene fiber to PVA fiber of 1:1-2:1.

[0010] Preferably, the method for preparing the excavable filling mortar includes: Take fly ash, bentonite and expansion agent and put them into a zero-gravity mixer. Dry mix for 5-8 minutes at a speed of 40-60 r / min to obtain the first premix. 60%-70% of the total mixing water is injected into the reactor. The reactor is started and rotated at 500-700 r / min. Sodium gluconate and citric acid are added in sequence and dispersed for 3-5 minutes to ensure that the additives are fully dissolved and dispersed, thus obtaining the second premix. The first premixed material and cement are simultaneously added into the reactor and stirred and dispersed for 8-10 minutes to form a uniform slurry. Yellow sand and crack-resistant fibers are added at a speed of 30-50 r / min and stirred for 5-8 minutes. Then the remaining mixing water is added and stirred at low speed for 10-15 minutes to mature, thus obtaining excavable filling mortar.

[0011] Preferably, the method for filling the shield tunnel soil chamber with low-strength excavable mortar includes: By pre-embedding an earth pressure sensor array in the earth chamber partition, the pressure distribution cloud map of each direction in the shield earth chamber is obtained based on the earth pressure sensor array, and the low-pressure area and high-pressure area of ​​the shield earth chamber are identified. Ultrasonic ranging was used to obtain the actual gap distribution between the back of the cutterhead and the soil chamber partition. A fluid model of the shield soil chamber filling space was constructed. Based on the fluid model of the filling space and the pressure distribution cloud map, the process of injecting and diffusing excavable filling mortar was simulated by computational fluid dynamics. A multi-objective optimization function for injecting excavable filling mortar is constructed with constraints such as minimum injection hole point, maximum injection pressure limit, and minimum injection hole point pressure difference. The particle optimization algorithm is used to solve the multi-objective optimization function and output the optimal injection scheme. To obtain the optimal injection scheme, inject excavable filling mortar into injection holes arranged along the circumference of the soil chamber based on the optimal injection scheme. The injection rate at a single point is 0.5-1m. 3 / h.

[0012] Preferably, the method for layered cleaning of the working face and graded fixing of the cutterhead includes: Phase 1: Clearing the upper empty chamber area of ​​the tunnel face and establishing the first support. Clear the backfill material in the upper 2m range of the No. 1 area inside the shield tunnel's soil chamber. After clearing, weld the first support platform cross brace, the No. 1 fixed steel section and the No. 2 fixed steel section of the cutterhead to the shield tunnel soil chamber wall and the cutterhead. At the same time, weld 4 Q355B material hoist lifting points to the shield tunnel soil chamber wall and the cutterhead as load-bearing and adjustment support points for subsequent operations. Then clear the backfill material in the No. 2 area inside the shield tunnel soil chamber. Subsequently, use a combination of steel bars, square timber or round timber to support the soil between piles within a 120° range of the 10-2 point on the arch top. One end of the steel bar is welded to the bottom support structure of the A-type bored pile, and the other end is driven into the B-type bored pile for no less than 200mm and welded and fixed. The gaps are sealed with quick-hardening cement to prevent mud and slag from falling from the arch top and behind. The middle part of the steel bar is welded to the main reinforcement of the bottom of the corresponding C-type and D-type bored piles. The second stage involves cleaning the backfill material in areas 3 and 4 within a 1.26m range between the cutterhead and the pile. After completion, the second support platform cross brace, the cutterhead fixed steel section 3, and the cutterhead fixed steel section 4 are welded to form a rigid connection between the cutterhead and the second support platform. The third stage: clean the backfill material in areas 5 and 6 within 1.26m between the cutterhead and the pile, and weld the horizontal and vertical supports of the third, fourth and fifth support platforms in sequence to form a 5-layer stepped support platform system. The design bearing capacity of each support platform is ≥80t. The support components are prefabricated in sections on the ground and assembled and welded in the compartment using box-shaped cross-section profiles. Phase 4: Clean up Area 7 within 1.26m of the excavation cutterhead and the B-type bored pile using water drills and pneumatic picks. Then clean up the backfill material in Area 8 of the excavation face. Weld the diagonal braces of the first, second, and third support platforms to form a combined support system of horizontal, diagonal, and vertical braces, so that the cutterhead can be stably constrained in three-dimensional space. The first, second, third, fourth, and fifth support platforms are made of Q355B material. Each support platform includes horizontal braces, diagonal braces, and vertical braces. The horizontal braces are made of Q355B material with a box-shaped cross-section, measuring 400mm×400mm×35mm×35mm. The length of each piece is manufactured in sections according to the inner diameter of the soil chamber. After being transported by personnel, they are assembled and welded inside the soil chamber. The vertical braces are also made of Q355B material with a box-shaped cross-section, measuring 300mm×300mm×16mm×16mm. The vertical braces are equipped with wedge-shaped adjustment steel plates or spiral adjustment supports to achieve fine-tuning of the support platform height, adapting to the support requirements under different cutterhead postures.

[0013] Preferably, the method of adjusting the cutter head posture by synchronously controlling multiple horizontal thrust cylinders through a hydraulic pump station includes: Four sets of horizontal pushing cylinders are evenly arranged in the circumference of the cutter head. Each set of horizontal pushing cylinders has a pushing and pulling force of not less than 50 tons and a stroke of 600-800mm. Inclination sensors, pressure sensors and displacement sensors are installed at the ends of the horizontal pushing cylinders. A three-dimensional laser scanner is installed in the circumference of the cutter head, and a strain sensor array is installed on the support platform. Based on the cutterhead design parameters, actual cutterhead detachment measurement parameters, and 3D scanning point cloud data of the shield tunnel soil chamber, a digital twin model of cutterhead-platform-cylinder is constructed. Based on the digital twin model, the attitude adjustment process of the cutterhead from the current attitude to the target attitude is simulated. The initial thrust distribution ratio, action timing and limit displacement threshold of each horizontal pushing cylinder are iteratively optimized to generate the optimal adjustment path. Based on the optimal adjustment path, the adjustment control command is triggered. The horizontal pushing cylinder responds to the adjustment control command, and multiple sets of horizontal pushing cylinders are controlled based on adaptive fuzzy PID control. Multi-source monitoring data are collected in real time, and the multi-source monitoring data are adaptively fused based on the Kalman filter algorithm to output an adaptive fused data stream. The adaptive fused data stream is linearly embedded and position encoded to obtain an encoded data stream. Load the encoded data stream, extract the spatiotemporal fusion features of the encoded data stream through a multi-head self-attention mechanism, perform global credential pooling on the spatiotemporal fusion features, and output the global pose feature vector. Based on the global feature vector recognition analysis of attitude using a dual-branch fully connected regression network, the actual output state of the horizontal pushing cylinder and the current pose of the cutter head are output. The current pose of the cutter head includes the horizontal offset, vertical offset, and rotational deviation. A coupling mapping relationship is established between the output state of the horizontal pushing cylinder and the change of the cutterhead pose. The coupling mapping adopts a residual network structure based on physical priors. The deviation between the target pose of the cutterhead and the current pose of the cutterhead is used as input. By solving the inverse problem of the coupling mapping, the target output increment of each cylinder is generated, and the target output increment is converted into a hydraulic pump station control command.

[0014] Preferably, the dual-branch fully connected regression network includes a pose regression branch and an output regression branch, with both branches sharing a bottom-level feature extraction layer. The bottom-level feature extraction layer adopts a 5-layer fully connected structure with the number of neurons being 512, 256, 128, 64, and 32 respectively. The activation function is the ReLU function, and the batch normalization layer is inserted after each hidden layer. The dropout ratio is set to 0.3. The loss function is the weighted mean square error. The dual-branch fully connected regression network is trained using a transfer learning strategy. First, a large-scale labeled sample is generated in a digital twin simulation environment for pre-training, and then a small sample is used for fine-tuning in the field. During fine-tuning, the parameters of the first 3 layers of the bottom-level feature extraction layer are frozen, and only the upper regression head and the last 2 feature extraction layers are optimized.

[0015] Preferably, the method for removing broken wires using welding-assisted extraction or countersinking tapping includes: Based on the inspection results upon entering the warehouse, broken wires are classified into three categories according to their fracture morphology: Category I broken wires: the fracture surface is exposed and the thread is not obviously stuck; Category II broken wires: the fracture surface is recessed or the thread is corroded and stuck; Category III broken wires: the root of the broken wire is broken or the thread is stripped. For Class I broken wires, a pneumatic impact wrench is used to directly apply force to the exposed end of the broken wire, using high-frequency impact force to overcome static friction and directly unscrew the broken wire; For Class II broken wires, select a standard hexagonal nut with a nominal diameter 1-2 sizes smaller than the original bolt as the welding base material. Place the nut above the broken wire end face, ensuring that the inner hole of the nut is coaxial with the broken wire. Use a segmented back-welding method to weld a fillet weld from the inside of the nut to the broken wire end face. The weld height should not be less than 0.7 times the nut wall thickness, and the cooling time should not be less than 5 minutes. After welding, use a hydraulic torque wrench or a pneumatic impact wrench to turn the nut and drive the broken wire out as a whole. For Class II process failures or Class III wire breakages, a magnetic drill is used to drill a process hole with a diameter of 80-120mm at the center of the broken wire. The hole depth penetrates the thickness of the cutter head flange and the remaining section of the broken wire. The process hole is then enlarged using a countersunk end mill until the hole diameter is 1-2mm larger than the bolt thread root diameter. The remaining broken wire and rusted threads in the hole are removed. The enlarged hole wall is then tapped with a tap to re-machine a trapezoidal or triangular thread that meets the tolerance requirements, restoring the threaded connection function. After thread repair and processing, once the broken thread is removed or the thread is reconstructed, use a wire brush to clean the iron filings inside the threaded hole, apply molybdenum disulfide grease, and use a go gauge and no-go gauge to inspect the thread accuracy. Only after passing the inspection can a new bolt be installed.

[0016] Preferably, the method for precisely aligning the cutterhead flange and the drive disc flange includes: The cutter head is moved to the vicinity of the drive disc flange by a horizontal thrust cylinder, and initial alignment is achieved by the cooperation between the outer edge guide cone surface of the cutter head and the corresponding cone surface of the drive disc. Insert 4-6 tapered locating pins between the blade disc flange and the drive disc flange. The diameter of the small end of the locating pin is 2-3mm smaller than the diameter of the bolt hole, and the taper is 1:20-1:50. The precise concentric positioning of the blade disc and the drive disc is achieved by hammering the locating pins. After the locating pins are installed, insert the connecting bolts according to the diagonal alternation and graded loading principle and tighten them initially. Then, use a hydraulic tensioner or hydraulic torque wrench to tighten them in three progressive stages of 30%-60%-100% of the design value. After each stage of tightening, use a marker to mark the relative position of the bolt head and the flange face to ensure that the tightening process is traceable.

[0017] Compared with the prior art, the embodiments of this application have the following main advantages: The present invention proposes a method for repairing the cutterhead during tunnel boring machine (TBM) excavation. This method achieves early warning of faults and pre-shutdown procedures by real-time monitoring of TBM excavation parameters, effectively preventing further damage to the cutterhead. By constructing a reinforced system of bored piles in front of and around the cutterhead, a retaining structure combining plain and rough piles is built. Combined with water-stop rings and low-strength excavable mortar, this forms an active stabilization system for the tunnel face and soil chamber environment, effectively blocking external water and soil pressure and significantly reducing the risk of face instability or water and sand inrush. Furthermore, by dividing the TBM soil chamber and tunnel face area into multiple working layers and employing a top-down, segmented, and cross-flow operation strategy for layered cleaning and graded fixing, multiple support platforms and inclined bracing are constructed between the cutterhead and the TBM soil chamber wall. The combined support system provides stable three-dimensional spatial constraints for the cutterhead. Multiple horizontally moving hydraulic cylinders are installed on the support platform, and based on digital twin pre-simulation, adaptive fuzzy PID control, and a dual-branch fully connected regression network, precise detection and intelligent control of the cutterhead's large-scale posture are achieved, ensuring that the horizontal, vertical, and angular deviations of the cutterhead meet high-precision reset requirements. A four-stage progressive broken wire removal process—intelligent material identification, graded energy welding, and micro-damage precision repair—combined with precise positioning using conical locating pins and graded progressive bolt tightening technology, ensures precise alignment and reliable connection between the cutterhead flange and the drive disc flange. Finally, through main drive pressure holding tests and cutterhead operation verification, the overall performance of the tunnel boring machine (TBM) is ensured to return to design requirements after repair. In summary, this invention enables in-situ repair of TBMs after major structural failures such as cutterhead detachment during tunnel excavation, eliminating the need for the TBM to exit the tunnel or add a surface shaft. This significantly shortens downtime, reduces maintenance costs, and avoids secondary disturbance to the surrounding strata, providing a systematic technical guarantee for the safe and continuous advancement of TBM construction under complex geological conditions.

[0018] In this embodiment of the invention, when preparing low-strength, controllable-expansion, excavable filling mortar, the micro-filling effect of fly ash and bentonite, and the bridging effect of polypropylene / PVA hybrid fibers are utilized. While ensuring high fluidity and volume stability of the mortar, the 28-day strength is precisely controlled within the easily excavable range of 0.5-2.0 MPa. This ensures sufficient self-support for maintaining face stability and avoids difficulties in manual and mechanical excavation during later cleaning due to excessive strength. Simultaneously, based on the pressure distribution cloud map of the soil chamber and ultrasonic ranging, a fluid model of the filling space is constructed. Combined with computational fluid dynamics simulation and particle optimization algorithm, an optimal injection scheme is generated. An intelligent injection method with multi-point synchronous, layered grouting and adaptive rate control is adopted, with the single-point injection rate strictly controlled within 0.5-1 m. 3 / h, effectively prevents deformation or sealing failure of the soil chamber partition caused by excessive local pressure, meets the requirements of face stability and soil chamber sealing during construction, and ensures efficient excavation and cleaning with conventional pneumatic picks in the later stage, significantly improving the safety and work efficiency of in-situ repair of the tunnel boring machine cutterhead.

[0019] In this embodiment of the invention, when adjusting the cutterhead posture by synchronously controlling multiple horizontal thrust cylinders through a hydraulic pump station, a precise cutterhead posture control system is constructed by uniformly arranging four sets of high-thrust horizontal thrust cylinders along the circumference of the cutterhead and integrating an array of multi-source sensors for tilt angle, pressure, and displacement. This is combined with three-dimensional laser scanning of the cutterhead and strain monitoring of the support platform. First, a digital twin model of the cutterhead-platform-cylinder system is constructed based on the cutterhead design parameters, actual drop measurement data, and three-dimensional point cloud of the soil chamber. Through simulation and iterative optimization, the initial thrust distribution, action sequence, and limit displacement threshold of each cylinder are determined, generating the optimal adjustment path as the control benchmark. Then, an adaptive fuzzy PID master-slave synchronous control architecture is adopted, using Kalman filtering to fuse multi-source monitoring data, and through linear... After sex-based embedding and positional encoding, a multi-head self-attention mechanism is used to extract spatiotemporal fusion features. After global average pooling, a two-branch fully connected regression network synchronously outputs the cutterhead pose (horizontal offset, vertical offset, and rotational deviation) and the actual output state of the hydraulic cylinders. The network adopts a pre-training-fine-tuning transfer learning strategy to improve its generalization ability in small sample scenarios. Finally, a physical prior-based residual network coupling mapping is established. By solving the inverse problem, the target output increment of each hydraulic cylinder is generated and converted into hydraulic pump station control commands. This achieves millimeter-level accurate detection and adaptive correction control of the large-scale pose of the cutterhead, effectively solving the problem of pose recovery after the cutterhead falls off in the limited space of the tunnel. It significantly improves the accuracy and efficiency of the cutterhead in-situ reset and ensures the alignment and connection reliability of the cutterhead and the drive plate after repair. Attached Figure Description

[0020] Figure 1 A schematic diagram illustrating the implementation process of the cutterhead repair method during tunnel boring machine excavation is shown.

[0021] Figure 2 A schematic diagram of the cutterhead structure of a tunnel boring machine in an embodiment of the present invention is shown.

[0022] Figure 3 A plan view of the bored pile reinforcement system in an embodiment of the present invention is shown.

[0023] Figure 4 A schematic diagram of the steel casing installation in an embodiment of the present invention is shown.

[0024] Figure 5 A schematic diagram of the support platform during layered cleaning of the face and graded fixing of the cutterhead is shown in an embodiment of the present invention.

[0025] Figure 6 The diagram shows the first stage of cleaning during the layered cleaning of the face and the grading and fixing of the cutterhead.

[0026] Figure 7The diagram shows the second-stage cleaning process during the layered cleaning of the face and the graded fixing of the cutterhead.

[0027] Figure 8 The diagram shows the third stage of cleaning during the layered cleaning of the face and the graded fixing of the cutterhead.

[0028] Figure 9 The diagram shows the fourth stage of cleaning during the layered cleaning of the face and the graded fixing of the cutterhead.

[0029] Figure 10 The diagram shows the fourth-stage diagonal and vertical bracing fixtures used during the layered cleaning of the face and the graded fixing of the cutterhead.

[0030] Figure 11 A schematic diagram illustrating the implementation process of a method for adjusting the cutter head posture by synchronously controlling multiple horizontal thrust cylinders through a hydraulic pump station is shown.

[0031] Figure 12 A schematic diagram of the installation position of the horizontal pushing cylinder in an embodiment of the present invention is shown. Detailed Implementation

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0033] Existing methods lack the ability to handle overall structural failures of the cutterhead. Furthermore, they lack an active stabilization system for the tunnel face and soil chamber environment. When performing repair work in high-risk strata, it is difficult to effectively block external water and soil pressure, easily inducing face instability or water and sand inrush risks. Simultaneously, there is a lack of precise detection and control methods for the large-scale position and orientation of the cutterhead. Relying solely on manual experience for welding repair makes it difficult to guarantee the alignment and installation accuracy of the repaired cutterhead, failing to meet the high standards required for overall cutterhead reset. To address these issues, we propose a cutterhead repair method during tunnel boring machine (TBM) excavation. In short, the method first acquires the TBM's tunneling operating parameters in real time, determines whether these parameters exceed preset abnormal parameter thresholds, and if so, initiates a repair process. If the operating parameters exceed the preset abnormal threshold, the tunnel boring machine (TBM) is shut down for pre-processing. Ground reinforcement is applied to the TBM shutdown area, and a reinforced pile system is constructed in front of and around the cutterhead. The TBM's soil chamber and face area are divided into multiple working layers. Layered cleaning of the face and graded fixing of the cutterhead are performed. Temporary fixing steel sections and support platforms are welded between the cutterhead and the TBM soil chamber wall. Multiple horizontal pushing cylinders are installed on the support platform. The hydraulic pump station synchronously controls the horizontal pushing cylinders to adjust the cutterhead's attitude and rotate the drive disc to align the broken bolt with the through hole. The broken bolt is removed using welding-assisted extraction or countersinking tapping. New bolts are replaced and pre-tightened simultaneously. Positioning pins and connecting bolts are installed and tightened to the designed torque. After completing the main drive pressure test and cutterhead operation verification, tunneling resumes. The present invention proposes a method for repairing the cutterhead during tunnel boring machine (TBM) excavation. This method achieves early warning of faults and pre-shutdown procedures by real-time monitoring of TBM excavation parameters, effectively preventing further damage to the cutterhead. By constructing a reinforced system of bored piles in front of and around the cutterhead, a retaining structure combining plain and rough piles is built. Combined with water-stop rings and low-strength excavable mortar, this forms an active stabilization system for the tunnel face and soil chamber environment, effectively blocking external water and soil pressure and significantly reducing the risk of face instability or water and sand inrush. Furthermore, by dividing the TBM soil chamber and tunnel face area into multiple working layers and employing a top-down, segmented, and cross-flow operation strategy for layered cleaning and graded fixing, multiple support platforms and inclined bracing are constructed between the cutterhead and the TBM soil chamber wall. The combined support system provides stable three-dimensional spatial constraints for the cutterhead. By installing multiple horizontally moving hydraulic cylinders on the support platform, and based on digital twin pre-simulation, adaptive fuzzy PID control, and a dual-branch fully connected regression network, the system achieves precise detection and intelligent control of the cutterhead's large-scale posture, ensuring that the horizontal offset, vertical offset, and angular deviation of the cutterhead meet the high-precision reset requirements. A four-stage progressive broken wire removal process—intelligent material recognition, graded energy welding, and micro-damage precision repair—combined with precise positioning using conical locating pins and graded progressive bolt tightening technology, ensures accurate alignment and reliable connection between the cutterhead flange and the drive disc flange. Finally, through main drive pressure holding tests and cutterhead operation verification, the system ensures that the overall performance of the tunnel boring machine is restored to design requirements after repair.In summary, this invention enables in-situ repair of shield tunneling machines after major structural failures such as cutterhead detachment occur during tunnel excavation. It eliminates the need for the shield tunneling machine to exit the tunnel or to construct additional ground shafts, significantly reducing downtime and maintenance costs. At the same time, it avoids secondary disturbance to the surrounding strata, providing a systematic technical guarantee for the safe and continuous advancement of shield tunneling under complex geological conditions.

[0034] This invention provides a method for repairing the cutterhead during the tunneling process of a tunnel boring machine. Figure 1 The diagram illustrates the implementation process of a cutterhead repair method during tunnel boring machine (TBM) excavation. The cutterhead repair method specifically includes: S10: Real-time acquisition of tunneling parameters of the tunnel boring machine (TBM), determining whether the parameters exceed preset abnormal thresholds. If the parameters exceed these thresholds, the TBM is shut down for pre-processing. These parameters include, but are not limited to, cutterhead torque, cutterhead speed, drive motor current and temperature, main bearing sealing grease pressure, total thrust, pressure and stroke difference of each hydraulic cylinder group, propulsion speed, multi-point pressure and pressure gradient of the soil chamber, screw conveyor torque and speed, excavated soil volume, soil temperature, TBM pitch and roll angles, and tail shield clearance. The determination of whether the parameters exceed the preset abnormal thresholds does not rely solely on static comparison of a single value, but employs a triple-judgment logic of static threshold limitation, dynamic trend analysis, and correlation coupling verification: First, a safe upper limit is set for the absolute values ​​of the cutterhead drive torque and total thrust. When real-time data exceeds this physical threshold... A Level 1 alarm is triggered under extreme conditions; then, the rate of change of the above parameters per unit time is monitored. If the thrust or torque suddenly drops or fluctuates violently without external disturbance, it is judged as a Level 2 anomaly. Most importantly, through the correlation and coupling verification logic, the theoretical mapping relationship between the drive current and the cutterhead speed and torque is compared in real time. When a decrease in drive system energy consumption is detected but a surge in cutterhead axial movement or attitude loss is detected, it is judged that the cutterhead and drive disc have suffered structural failure (such as bolt breakage or complete detachment), thereby accurately triggering a shutdown preprocessing command within milliseconds to avoid secondary disasters caused by delayed shutdown. The tunnel boring machine adopts a composite cutterhead, with a total weight of approximately 560T, a digging diameter of 7080mm, a cutterhead speed of 0-2.2rpm, and a cutterhead opening ratio of 40%. The maximum thrust is 560T, the maximum tunneling speed can reach 80mm / min, and the minimum horizontal turning radius is 250m. Figure 2 The diagram shows a schematic of the cutterhead structure of a tunnel boring machine in an embodiment of the present invention. The cutterhead adopts a four-main-beam combined with a four-panel structure. The cutterhead excavation diameter is φ7080mm, the overall opening rate is 40%, and the openings are evenly distributed. The cutterhead is equipped with 4 central double-roll cutters, 35 front roll cutters, 17 welding tear cutters, 44 scrapers, 8 sets of side scrapers, and 8 diameter-maintaining cutters.

[0035] S20, for the ground reinforcement treatment at the location where the tunnel boring machine stops, a drilled pile reinforcement system is constructed in front of and around the cutterhead; S30, based on the top-down, segmented advancement rule, divides the shield tunnel soil chamber and face area into multiple working layers, performs layered cleaning of the face and graded fixing of the cutterhead, and welds temporary fixing steel and support platform between the cutterhead and the shield tunnel soil chamber wall. S40, remove the temporary fixed steel section, install multiple horizontal pushing cylinders on the support platform, and adjust the cutter head posture by synchronously controlling multiple horizontal pushing cylinders through the hydraulic pump station; S50, an operating through hole is opened at the corresponding position of the cutter head flange. The drive disc is rotated to align the broken bolt with the through hole. The broken bolt is removed by welding-assisted extraction or countersinking and tapping process. At the same time, a new bolt is replaced and pre-tightened. S60: Precisely align the cutterhead flange with the drive disc flange, install the locating pins and connecting bolts and tighten them to the designed torque, and resume tunneling after completing the main drive pressure holding test and cutterhead operation verification.

[0036] This invention provides a method for constructing a bored pile reinforcement system in front of and around the cutterhead. Figure 3 This invention illustrates a plan view of the bored pile reinforcement system in an embodiment of the invention. The method for constructing the bored pile reinforcement system in front of and around the cutterhead specifically includes: S101, multiple water-stopping rings are installed at the circumferential ring segments where the tunnel boring machine stops, and low-strength excavable filling mortar is filled into the tunnel soil chamber. Before constructing the bored pile reinforcement system in front of and around the cutterhead, the surrounding environment of the reinforcement area and the strata in front of the cutterhead are analyzed. Along the tunnel direction, the presence and burial depth of shared pipelines such as communication lines and cables are investigated. After the construction area is fenced off, further manual excavation is conducted to clarify the routes of communication lines and cables within the construction area. During construction, communication lines and cables are excavated and protected, with dedicated personnel monitoring the process, and a coordination mechanism is established with the property owner. Next, the condition of the tunnel face is analyzed, and the outward protrusion data of the tunnel face needs to be obtained.

[0037] S102, a drilled pile array is laid in front of and above the tunnel boring machine, and the tunnel boring machine is reinforced by the drilled pile array. The drilled pile array includes type A drilled piles, type B drilled piles, type C drilled piles, type D drilled piles, and type E drilled piles. Among them, type A drilled piles include A1-A8 drilled piles, type B drilled piles include B1-B17 drilled piles, type C drilled piles include C1-C8 drilled piles, and type D drilled piles include D1-D8 drilled piles. The diameter of the drilled piles is 1m. After the pile foundation in the empty pile area is completed, C20 concrete is backfilled. A steel casing is buried in the stratum area above the type E drilled piles. The bottom of the steel casing is embedded in the stable bearing layer for more than 1 meter, and the top of the steel casing is higher than the stratum above it for more than 1 meter. A triangular stiffening steel plate is welded to the outside of the steel casing. The stiffening steel plate has a top 5-8cm, a bottom 12-18cm, a height of 8-12cm, and a thickness of 1.5-2.5cm. in, Figure 4 The diagram shows the installation of the steel casing in an embodiment of the present invention. After the steel casing is lowered, it is 10cm above the ground. After the steel casing is buried, the opening is sealed by welding with steel mesh. The remaining 90cm is welded after all pile positions are completed. Before entering the silo, eight triangular steel plates (trapezoidal steel plates, 5cm at the top, 15cm at the bottom, 10cm high, and 2cm thick) are welded to the outside of the steel casing, and the other side is tightly attached to the ground to prevent the steel casing from sinking.

[0038] The bottom of S103 and B1-B17 bored piles is reinforced with an 11m long glass fiber reinforced steel cage. The C1-C8 and D1-D8 bored piles are reinforced with additional steel cages on the outside. The steel bars of the C1-C8 and D1-D8 bored piles are anchored into the upper part to form an extension plate and placed on the B-type bored piles.

[0039] In this embodiment of the invention, a reinforcing cage is placed outside the C-type bored pile for reinforcement. Since the main function of this reinforcing cage is tensile strength, the following formula is used for calculation: The self-weight of a single pile is G = 25 * 3.14 * 0.5 * 0.5 * 16 = 314 kN. The diameter of the reinforcing bar is 20 mm. The bearing capacity of a single reinforcing bar is fy * As = 360 * 314.2 / 1000 = 113 kN. The number of bars is 1.1 * 1.35 * 314 / 113 = 4.12 (not considering cracks). This project uses Ø20 mm threaded steel for the main reinforcement, φ8 mm @ 400 mm for the stirrups, and Ø18 mm steel for the reinforcing hoops. A 0.4 m cap plate is installed on the top of all piles to hold the pile body in place. Direct settlement monitoring points are embedded on the top surface of the cast-in-place pile concrete. The monitoring data dynamically guides the construction within the pile. The vertical monitoring points are located at piles A2 and A5.

[0040] In this embodiment of the invention, the excavable filling mortar comprises the following raw materials in parts by weight: 30-50 parts cement, 300-400 parts fly ash, 450-550 parts yellow sand, 120-150 parts bentonite, 8-15 parts expansion agent, 1-10 parts sodium gluconate, 2-4 parts crack-resistant fiber, 1-5 parts citric acid, and 450-500 parts mixing water. Among them, the crack-resistant fiber is a blend of polypropylene fiber and PVA fiber, with a mass ratio of polypropylene fiber to PVA fiber of 1:1-2:1.

[0041] The method for preparing excavable filling mortar includes: S201, take fly ash, bentonite and expansion agent into a zero-gravity mixer, dry mix for 5-8 minutes at a speed of 40-60 r / min to obtain the first premix; S202, inject 60%-70% of the total mixing water into the reactor, start the reactor, the reactor speed is 500-700 r / min, add sodium gluconate and citric acid in sequence, and disperse for 3-5 minutes to fully dissolve and disperse the additives to obtain the second premix; S203: The first premixed material and cement are simultaneously added into the reactor and stirred and dispersed for 8-10 minutes to form a uniform slurry. Yellow sand and crack-resistant fibers are added at a speed of 30-50 r / min and stirred for 5-8 minutes. Then, the remaining mixing water is added and stirred at low speed for 10-15 minutes to prepare excavable filling mortar.

[0042] In this embodiment of the invention, the method of filling the shield tunnel soil chamber with low-strength excavable mortar includes: S301 uses an earth pressure sensor array pre-embedded in the earth pressure chamber partition to obtain pressure distribution cloud maps of all directions in the shield earth chamber based on the earth pressure sensor array, and identifies the low-pressure and high-pressure areas in the shield earth chamber. S302 uses ultrasonic ranging to obtain the actual gap distribution between the back of the cutterhead and the soil chamber partition, and constructs a fluid model of the shield soil chamber filling space. Using the fluid model of the filling space and the pressure distribution cloud map as priors, it combines computational fluid dynamics simulation to simulate the injection and diffusion process of excavable filling mortar. S303, with the minimum injection hole point, the maximum injection pressure limit, and the minimum injection hole point pressure difference as constraints, constructs a multi-objective optimization function for excavable filling mortar injection, and uses a particle optimization algorithm to solve the multi-objective optimization function to output the optimal injection scheme; S304. Obtain the optimal injection scheme. Based on the optimal injection scheme, inject excavable filling mortar into injection holes arranged along the circumference of the soil chamber. The injection rate at a single point is 0.5-1m. 3 / h.

[0043] In this embodiment of the invention, when preparing low-strength, controllable-expansion, excavable filling mortar, the micro-filling effect of fly ash and bentonite, and the bridging effect of polypropylene / PVA hybrid fibers are utilized. While ensuring high fluidity and volume stability of the mortar, the 28-day strength is precisely controlled within the easily excavable range of 0.5-2.0 MPa. This ensures sufficient self-support for maintaining face stability and avoids difficulties in manual and mechanical excavation during later cleaning due to excessive strength. Simultaneously, based on the pressure distribution cloud map of the soil chamber and ultrasonic ranging, a fluid model of the filling space is constructed. Combined with computational fluid dynamics simulation and particle optimization algorithm, an optimal injection scheme is generated. An intelligent injection method with multi-point synchronous, layered grouting and adaptive rate control is adopted, with the single-point injection rate strictly controlled within 0.5-1 m. 3 / h, effectively prevents deformation or sealing failure of the soil chamber partition caused by excessive local pressure, meets the requirements of face stability and soil chamber sealing during construction, and ensures efficient excavation and cleaning with conventional pneumatic picks in the later stage, significantly improving the safety and work efficiency of in-situ repair of the tunnel boring machine cutterhead.

[0044] This invention provides a method for layered cleaning of the face tunnel and graded fixing of the cutterhead, wherein... Figure 5 This diagram illustrates a support platform for layered cleaning and graded fixing of the cutterhead at the working face, as shown in an embodiment of the present invention. It should be noted that the support platform refers to a five-layered stepped support platform system consisting of a first support platform, a second support platform, a third support platform, a fourth support platform, and a fifth support platform. The method for layered cleaning and graded fixing of the cutterhead at the working face specifically includes: S401, Phase 1: Clearing the empty area above the working face and establishing the first support. Figure 6This diagram illustrates the first stage of cleaning during the layered cleaning of the tunnel face and the graded fixing of the cutterhead. The process involves cleaning the backfill material in the upper 2m area of ​​the shield tunnel's soil chamber, specifically area #1. After cleaning, the first support platform cross brace, cutterhead #1 fixing steel, and #2 fixing steel are welded to the shield tunnel's soil chamber wall and cutterhead. Simultaneously, four Q355B material hoist lifting points (30mm thick steel plates) are welded to the shield tunnel's soil chamber wall and cutterhead to serve as load-bearing and adjustment fulcrums for subsequent operations. Then, the backfill material in area #2 of the shield tunnel's soil chamber is cleaned, followed by the cleaning of point 10-2 on the arch. Within a 120° range, the soil between piles is supported by a combination of steel bars, square timber, or round timber. One end of the steel bar is welded to the bottom support structure of the type A bored pile, and the other end is driven into the type B bored pile at least 200mm and welded in place. Gaps are sealed with quick-setting cement to prevent mud and debris from falling from the arch and behind. The middle of the steel bar is welded to the main reinforcement of the bottom of the corresponding type C or type D bored pile. To ensure the stability of the soil above the arch during cutterhead repositioning, steel bars, square timber, or round timber are used to support and protect the soil between piles within a 120° range at points 10-2 on the arch. The bottom support of the type A bored piles mainly prevents mud and debris from falling from the arch and behind; the soil support between the type C and type D bored piles mainly prevents the top soil between piles from falling; and the soil support between the type B bored piles mainly prevents the front soil between piles from falling. Simultaneously, the spacing of the steel bars is adjusted according to the actual site conditions, and welded reinforcement is added as necessary. Square timber is 100cm long * 9.5cm wide * 9.5cm high; round timber is 52cm long * 63mm in diameter; long strips are 400cm long * 9cm wide * 3.5cm high, and should be cut according to site requirements.

[0045] S402, Phase Two: Cleaning the backfill material in areas 3 and 4 within a 1.26m range between the cutterhead and the piles. Area 4 is the area within 1.1m of the shield tunnel excavation face. The volume of backfill material in area 3 is approximately 6.6 cubic meters, while the volume of backfill material in area 4 is approximately 6.8 cubic meters. Figure 7 The diagram shows the second stage of cleaning during the layered cleaning of the face and the graded fixing of the cutterhead. After completion, the second support platform cross brace, the cutterhead #3 fixed steel and #4 fixed steel are welded to form a rigid connection between the cutterhead and the second support platform. S403, Phase 3: Cleaning the backfill material in areas 5 and 6 within a 1.26m range between the cutterhead and the piles. Area 6 is located 2.9m below the excavation surface of the soil chamber. The volume of backfill material in area 5 is approximately 12.1 cubic meters, and the volume of backfill material in area 6 is approximately 17.8 cubic meters. Figure 8 The diagram shows the third stage of cleaning during the layered cleaning of the face and the graded fixing of the cutterhead. The third, fourth, and fifth support platforms are welded in sequence with horizontal and vertical supports to form a 5-layer stepped support platform system. Each support platform is designed to have a load-bearing capacity of ≥80t. The support components are prefabricated in sections on the ground and assembled and welded inside the chamber using box-shaped cross-section profiles. S404, Phase 4: The 1.26m area between the cutterhead and the B-type bored pile (Area 7) is cleared using water-cooled drills and pneumatic picks. Then, the backfill material in Area 8 of the excavation face is cleared. Area 7 has a volume of approximately 15.3 cubic meters, while Area 8 has a volume of approximately 12.5 cubic meters. The first, second, and third support platforms are welded with diagonal braces to form a combined horizontal, diagonal, and vertical brace support system, providing stable constraint to the cutterhead in three-dimensional space. Figure 9 The diagram illustrates the fourth stage of cleaning during the layered cleaning process at the face of the cutting tool and the grading and fixing of the cutterhead. Figure 10 This diagram illustrates the fourth-stage diagonal and vertical bracing fixtures used during the layered cleaning process at the face of the cutting head and the graded fixing of the cutterhead. Figure 10 In the diagram, diagonal braces 1, 2, and 3 correspond to the diagonal braces of the first support platform, the second support platform, and the third support platform, respectively. The first, second, third, fourth, and fifth support platforms are made of Q355B material. Each support platform includes horizontal braces, diagonal braces, and vertical braces. The horizontal braces are made of Q355B material with a box-shaped cross-section, measuring 400mm×400mm×35mm×35mm. The length of each piece is manufactured in sections according to the inner diameter of the soil chamber. After being transported by personnel, they are assembled and welded inside the soil chamber. The vertical braces are also made of Q355B material with a box-shaped cross-section, measuring 300mm×300mm×16mm×16mm. The vertical braces are equipped with wedge-shaped adjustment steel plates or spiral adjustment supports to achieve fine-tuning of the support platform height, adapting to the support requirements under different cutterhead postures.

[0046] In this embodiment of the invention, excavation must be carried out strictly according to the predetermined excavation depth and range to ensure that the surrounding soil structure is not damaged. During the cleaning of the shield tunneling earth chamber, soil, stones, and other debris should be thoroughly removed to ensure the interior of the earth chamber is clean and tidy, providing at least 500mm of working face space in front of the tunnel face to facilitate subsequent cutterhead repositioning. For safety during the cleaning and initial work within the shield tunneling earth chamber, and to prevent the cutterhead from moving or falling again, the cutterhead must be secured. Based on the site conditions, four points are selected to firmly weld the cutterhead to the earth chamber wall, and the lower support platform is used to fix the cutterhead flange directly below.

[0047] This invention provides a method for adjusting the cutter head posture by synchronously controlling multiple horizontal thrust cylinders using a hydraulic pump station. Figure 11 A schematic diagram illustrating the implementation process of a method for adjusting the cutter head posture by synchronously controlling multiple horizontal thrust cylinders via a hydraulic pump station is shown. The method specifically includes: The S501 comprises four sets of horizontally moving hydraulic cylinders evenly arranged around the circumference of the cutter head. Each set of cylinders has a pushing / pulling force of no less than 50 tons and a stroke of 600-800 mm. Inclination sensors, pressure sensors, and displacement sensors are installed at the ends of the cylinders. A 3D laser scanner is circumferentially mounted on the cutter head, and a strain sensor array is installed on the support platform. The four sets of horizontally moving hydraulic cylinders are designated as Horizontal Moving Cylinder 1, Horizontal Moving Cylinder 2, Horizontal Moving Cylinder 3, and Horizontal Moving Cylinder 4. These cylinders can be installed on the first, second, third, and fourth support platforms, respectively. Figure 12 A schematic diagram of the installation position of the horizontal pushing cylinder in an embodiment of the present invention is shown; S502 constructs a digital twin model of cutterhead-platform-cylinder based on cutterhead design parameters, actual cutterhead detachment measurement parameters, and 3D scanning point cloud data of shield tunnel soil chamber. Based on the digital twin model, it simulates the attitude adjustment process of the cutterhead from the current attitude to the target attitude, iteratively optimizes the initial thrust distribution ratio, action timing and limit displacement threshold of each horizontal pushing cylinder, generates the optimal adjustment path, and triggers adjustment control commands based on the optimal adjustment path. S503, the horizontal push cylinder responds to the adjustment control command, and multiple sets of horizontal push cylinders are controlled based on adaptive fuzzy PID control. Multi-source monitoring data is collected in real time, and the multi-source monitoring data is adaptively fused based on the Kalman filter algorithm to output an adaptive fused data stream. The adaptive fused data stream is linearly embedded and position encoded to obtain an encoded data stream. S504 loads the encoded data stream, extracts the spatiotemporal fusion features of the encoded data stream through a multi-head self-attention mechanism, performs global credential pooling on the spatiotemporal fusion features, and outputs a global pose feature vector. S505, based on a dual-branch fully connected regression network, identifies and analyzes the global feature vector of the attitude, and outputs the actual output state of the horizontal pushing cylinder and the current position of the cutter head. The current position of the cutter head includes the horizontal offset, vertical offset, and rotational deviation. The dual-branch fully connected regression network includes a pose regression branch and an output regression branch, with both branches sharing a bottom-level feature extraction layer. The bottom-level feature extraction layer adopts a 5-layer fully connected structure with 512, 256, 128, 64, and 32 neurons respectively. The activation function is the ReLU function, and the batch normalization layer is inserted after each hidden layer. The dropout ratio is set to 0.3. The loss function is the weighted mean square error. The dual-branch fully connected regression network is trained using a transfer learning strategy. First, a large number of labeled samples are generated in a digital twin simulation environment for pre-training, and then small samples are used for fine-tuning in the field. During fine-tuning, the parameters of the first 3 layers of the bottom-level feature extraction layer are frozen, and only the upper regression head and the last 2 feature extraction layers are optimized.

[0048] S506, Establish the coupling mapping relationship between the output state of the horizontal pushing cylinder and the change of the cutter head pose. The coupling mapping adopts a residual network structure based on physical priors. The deviation between the target pose of the cutter head and the current pose of the cutter head is used as input. By solving the inverse problem of the coupling mapping, the target output increment of each cylinder is generated, and the target output increment is converted into a hydraulic pump station control command.

[0049] In this embodiment of the invention, when adjusting the cutterhead posture by synchronously controlling multiple horizontal thrust cylinders through a hydraulic pump station, a precise cutterhead posture control system is constructed by uniformly arranging four sets of high-thrust horizontal thrust cylinders along the circumference of the cutterhead and integrating an array of multi-source sensors for tilt angle, pressure, and displacement. This is combined with three-dimensional laser scanning of the cutterhead and strain monitoring of the support platform. First, a digital twin model of the cutterhead-platform-cylinder system is constructed based on the cutterhead design parameters, actual drop measurement data, and three-dimensional point cloud of the soil chamber. Through simulation and iterative optimization, the initial thrust distribution, action sequence, and limit displacement threshold of each cylinder are determined, generating the optimal adjustment path as the control benchmark. Then, an adaptive fuzzy PID master-slave synchronous control architecture is adopted, using Kalman filtering to fuse multi-source monitoring data, and through linear... After sex-based embedding and positional encoding, a multi-head self-attention mechanism is used to extract spatiotemporal fusion features. After global average pooling, a two-branch fully connected regression network synchronously outputs the cutterhead pose (horizontal offset, vertical offset, and rotational deviation) and the actual output state of the hydraulic cylinders. The network adopts a pre-training-fine-tuning transfer learning strategy to improve its generalization ability in small sample scenarios. Finally, a physical prior-based residual network coupling mapping is established. By solving the inverse problem, the target output increment of each hydraulic cylinder is generated and converted into hydraulic pump station control commands. This achieves millimeter-level accurate detection and adaptive correction control of the large-scale pose of the cutterhead, effectively solving the problem of pose recovery after the cutterhead falls off in the limited space of the tunnel. It significantly improves the accuracy and efficiency of the cutterhead in-situ reset and ensures the alignment and connection reliability of the cutterhead and the drive plate after repair.

[0050] This invention provides a method for removing broken wires using welding-assisted extraction or countersinking and tapping processes. The method specifically includes: S601, based on the inspection results upon entry into the warehouse, broken wires are classified into three categories according to their fracture morphology: Category I broken wires: the fracture surface is exposed and the thread is not obviously stuck. These broken wires are usually caused by overload shearing, the thread pair is relatively intact, and the removal is the easiest; Category II broken wires: the fracture surface is recessed or the thread is corroded and stuck. This is mostly caused by the coupling effect of long-term electrochemical corrosion and fretting wear. There is a dense layer of corrosion products at the thread pair interface, and removal requires overcoming significant frictional resistance; Category III broken wires: the root of the broken wire is broken or the thread is stripped. This is an extreme case of fatigue fracture or thread load failure, and conventional unscrewing methods are completely ineffective. After classification, a portable endoscope and a miniature industrial camera are used to acquire 360° images of each broken wire, recording the fracture surface morphology, recess depth, and damage status of the surrounding base material, establishing a three-dimensional information file of the broken wire to provide a basis for subsequent process selection; S602, for Class I broken wires, uses a pneumatic impact wrench to directly apply to the exposed end of the broken wire, using high-frequency impact force to overcome static friction and directly unscrew the broken wire; For S603, for Class II broken wires, select a standard hexagonal nut with a nominal diameter 1-2 sizes smaller than the original bolt as the welding base material. Place the nut above the broken wire end face, ensuring that the inner hole of the nut is coaxial with the broken wire. Use a segmented back-welding method to weld a fillet weld from the inside of the nut to the broken wire end face. The weld height should not be less than 0.7 times the nut wall thickness, and the cooling time should not be less than 5 minutes. After welding, use a hydraulic torque wrench or a pneumatic impact wrench to turn the nut and drive the broken wire out as a whole. For S604, which addresses Class II process failures or Class III wire breakage, a magnetic drill is used to drill a process hole with a diameter of 80-120mm at the center of the broken wire. The hole depth penetrates the thickness of the cutter head flange and the remaining section of the broken wire. A countersunk end mill is then used to enlarge the process hole until the hole diameter is 1-2mm larger than the bolt thread root diameter. The remaining broken wire and rusted threads in the hole are removed. A tap is then used to tap the wall of the enlarged hole to re-machine a trapezoidal or triangular thread that meets the tolerance requirements, restoring the threaded connection function. S605, Post-Thread Repair Process: After removing broken threads or reconstructing the thread, clean the metal filings from the threaded hole with a wire brush, apply molybdenum disulfide grease, and inspect the thread accuracy using go and no-go gauges. Only after passing the inspection can new bolts be installed. The grease film thickness is 0.05-0.10mm, which reduces the friction coefficient of subsequent bolt insertion and provides long-term rust protection. Before installing new bolts, the thread accuracy is checked again using go and no-go gauges. Only after the go gauge is fully through and the no-go gauge is at stop can the formal connection be made. All repaired threaded holes are numbered and registered, linked to the original broken thread file, forming a traceable maintenance record.

[0051] In this embodiment of the invention, when removing broken wires using welding-assisted extraction or countersinking tapping processes, a progressive repair system based on "morphological grading, thermal de-clamping, and structural reconstruction" is constructed. This effectively overcomes the problems of high-strength fasteners being "unremovable, prone to misalignment, and damaging to the base material" in confined spaces. When removing broken wires, a three-level classification diagnosis based on the broken wire morphology is first used to accurately match differentiated treatment strategies, avoiding secondary damage to the cutter head flange caused by blind operation. Secondly, for stubborn broken wires, a "segmented back-welding method" is used. By controlling the heat input direction and interlayer cooling time, the welding thermal stress is used to destroy the rust and seizure between threads, while also preventing... This prevented the flange body from annealing and deforming due to localized overheating, significantly improving the reliability of the welded reinforcement structure. Finally, for extreme working conditions such as root fracture or stripped threads, an innovative large-diameter drilling and milling and thread reconstruction process was adopted to thoroughly remove the residual stress concentration area of ​​the failed thread and re-establish a high-precision thread pair. This not only restored the connection function but also improved the structural strength of the repair point by increasing the thread bearing area. Combined with subsequent molybdenum disulfide lubrication and go / no-go gauge calibration, the precise application of the new bolt preload was ensured, fundamentally eliminating the risk of undercut and loose tightening during the re-tightening process, and greatly improving the fault tolerance and long-term reliability of the cutter head repair.

[0052] This invention also provides a method for precisely aligning the cutterhead flange and the drive disc flange. The method specifically includes: S701, based on the horizontal pushing hydraulic cylinder, moves the cutter head to the vicinity of the drive plate flange surface. The initial centering is achieved by the cooperation between the outer edge guide cone surface of the cutter head and the corresponding cone surface of the drive plate. After the coarse adjustment is completed, the uniformity of the gap around the cone surface is checked by the feeler gauge. If there is obvious skew, it is eliminated by fine adjustment by the single point hydraulic cylinder. S702, insert 4-6 tapered locating pins between the blade disc flange face and the drive disc flange face. The diameter of the small end of the locating pin is 2-3mm smaller than the diameter of the bolt hole, and the taper is 1:20-1:50. The precise concentric positioning of the blade disc and the drive disc is achieved by hammering the locating pins. After installing the S703 locating pins, insert the connecting bolts according to the diagonal alternating, graded loading principle and tighten them initially. Then, use a hydraulic tensioner or hydraulic torque wrench to tighten them in three progressive stages: 30%-60%-100% of the design value. After each stage of tightening, mark the relative position of the bolt head and flange face with a marker to ensure the tightening process is traceable. After the cutter head is reset and the drive plate is re-tightened, restore the center rotary pipeline and accessories, and perform a pressure holding test on the main drive for a period of time to observe pressure changes. At the same time, a comprehensive inspection of the overall condition after the cutter head is reset is required, including the bolt tightness and the flexibility of the cutter head operation, to ensure that all components are in normal condition and meet the usage requirements.

[0053] In summary, this invention provides a method for repairing the cutterhead during tunnel boring machine (TBM) excavation. This method achieves early warning of faults and pre-shutdown procedures by real-time monitoring of TBM excavation parameters, effectively preventing further damage to the cutterhead. By constructing a reinforced pile system in front of and around the cutterhead, a combined plain and rough pile retaining structure is built, along with water-stop rings and low-strength excavable mortar, forming an active stabilization system for the tunnel face and soil chamber environment. This effectively blocks external water and soil pressure, significantly reducing the risk of face instability or water and sand inrush. Furthermore, by dividing the TBM soil chamber and tunnel face area into multiple working layers and employing a top-down, segmented, and cross-flow operation strategy for layered cleaning and graded fixing, a method is established between the cutterhead and the TBM soil chamber wall. A multi-support platform and a combined diagonal-vertical brace support system were constructed to provide stable three-dimensional spatial constraints for the cutterhead. Multiple horizontally moving hydraulic cylinders were installed on the support platforms, and based on digital twin pre-simulation, adaptive fuzzy PID control, and a dual-branch fully connected regression network, precise detection and intelligent control of the cutterhead's large-scale posture were achieved, ensuring that the horizontal, vertical, and angular deviations of the cutterhead met high-precision reset requirements. A four-stage progressive broken wire removal process—intelligent material identification, graded energy welding, and micro-damage precision repair—was employed, combined with precise positioning using conical locating pins and graded progressive bolt tightening technology, to achieve precise alignment and reliable connection between the cutterhead flange and the drive disc flange. Finally, through main drive pressure holding tests and cutterhead operation verification, the overall performance of the tunnel boring machine was ensured to be restored to design requirements after repair. In summary, this invention enables in-situ repair of shield tunneling machines after major structural failures such as cutterhead detachment occur during tunnel excavation. It eliminates the need for the shield tunneling machine to exit the tunnel or to construct additional ground shafts, significantly reducing downtime and maintenance costs. At the same time, it avoids secondary disturbance to the surrounding strata, providing a systematic technical guarantee for the safe and continuous advancement of shield tunneling under complex geological conditions.

[0054] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of the present invention according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of the present invention. These technical solutions also fall within the scope of protection of the present invention.

Claims

1. A method for repairing the cutterhead during tunnel boring machine excavation, characterized in that, The method includes: The tunnel boring machine's tunneling parameters are acquired in real time, and it is determined whether the tunneling parameters exceed the preset abnormal parameter threshold. If the tunneling parameters exceed the preset abnormal parameter threshold, the tunnel boring machine is stopped for pre-processing. For the ground reinforcement treatment at the location where the tunnel boring machine stops, a drilled pile reinforcement system is constructed in front of and around the cutterhead; Based on the top-down, segmented advancement rule, the shield tunnel soil chamber and face area are divided into multiple working layers. The face is cleaned in layers and the cutterhead is fixed in stages. Temporary fixing steel and support platform are welded between the cutterhead and the shield tunnel soil chamber wall. Remove the temporary fixed steel section, install multiple horizontal pushing cylinders on the support platform, and use the hydraulic pump station to synchronously control the multiple horizontal pushing cylinders to adjust the attitude of the cutter head; Open an operating through hole at the corresponding position on the cutter head flange, rotate the drive disc to align the broken bolt with the through hole, and remove the broken wire by welding-assisted extraction or countersinking and tapping process, and simultaneously replace and pre-tighten the new bolt. Precisely align the cutterhead flange with the drive disc flange, install the locating pins and connecting bolts and tighten them to the designed torque. After completing the main drive pressure holding test and cutterhead operation verification, resume tunneling.

2. The method for repairing the cutterhead during tunnel boring machine excavation as described in claim 1, characterized in that: Methods for constructing bored pile reinforcement systems in front of and around the cutterhead include: Multiple water-stopping rings were installed at the circumferential ring segments where the tunnel boring machine was stopped, and low-strength excavable filling mortar was filled into the tunnel soil chamber. Drilled pile arrays are laid in front of and above the tunnel boring machine, and the tunnel boring machine is reinforced by the drilled pile arrays. The drilled pile arrays include type A drilled piles, type B drilled piles, type C drilled piles, type D drilled piles, and type E drilled piles. Among them, type A drilled piles include drilled piles A1-A8, type B drilled piles include drilled piles B1-B17, type C drilled piles include drilled piles C1-C8, and type D drilled piles include drilled piles D1-D8. The bottom of the B1-B17 bored piles is reinforced with an 11m long glass fiber reinforced steel cage. The C1-C8 and D1-D8 bored piles are reinforced with additional steel cages on the outside. The steel bars of the C1-C8 and D1-D8 bored piles are anchored into the upper part to form an extension plate, which is then placed on the B-type bored piles.

3. The method for repairing the cutterhead during tunnel boring machine excavation as described in claim 2, characterized in that: The excavable filling mortar comprises the following raw materials in parts by weight: 30-50 parts cement, 300-400 parts fly ash, 450-550 parts yellow sand, 120-150 parts bentonite, 8-15 parts expansion agent, 1-10 parts sodium gluconate, 2-4 parts crack-resistant fiber, 1-5 parts citric acid, and 450-500 parts mixing water. Among them, the crack-resistant fiber is a blend of polypropylene fiber and PVA fiber, with a mass ratio of polypropylene fiber to PVA fiber of 1:1-2:

1.

4. The method for repairing the cutterhead during tunnel boring machine excavation as described in claim 3, characterized in that: The method for preparing excavable filling mortar includes: Take fly ash, bentonite and expansion agent and put them into a zero-gravity mixer. Dry mix for 5-8 minutes at a speed of 40-60 r / min to obtain the first premix. 60%-70% of the total mixing water is injected into the reactor. The reactor is started and rotated at 500-700 r / min. Sodium gluconate and citric acid are added in sequence and dispersed for 3-5 minutes to ensure that the additives are fully dissolved and dispersed, thus obtaining the second premix. The first premixed material and cement are simultaneously added into the reactor and stirred and dispersed for 8-10 minutes to form a uniform slurry. Yellow sand and crack-resistant fibers are added at a speed of 30-50 r / min and stirred for 5-8 minutes. Then the remaining mixing water is added and stirred at low speed for 10-15 minutes to mature, thus obtaining excavable filling mortar.

5. The method for repairing the cutterhead during tunnel boring machine excavation as described in claim 4, characterized in that: The method for filling the shield tunnel soil chamber with low-strength excavable mortar includes: By pre-embedding an earth pressure sensor array in the earth chamber partition, the pressure distribution cloud map of each direction in the shield earth chamber is obtained based on the earth pressure sensor array, and the low-pressure area and high-pressure area of ​​the shield earth chamber are identified. Ultrasonic ranging was used to obtain the actual gap distribution between the back of the cutterhead and the soil chamber partition. A fluid model of the shield soil chamber filling space was constructed. Based on the fluid model of the filling space and the pressure distribution cloud map, the process of injecting and diffusing excavable filling mortar was simulated by computational fluid dynamics. A multi-objective optimization function for injecting excavable filling mortar is constructed with constraints such as minimum injection hole point, maximum injection pressure limit, and minimum injection hole point pressure difference. The particle optimization algorithm is used to solve the multi-objective optimization function and output the optimal injection scheme. To obtain the optimal injection scheme, inject excavable filling mortar into injection holes arranged along the circumference of the soil chamber based on the optimal injection scheme. The injection rate at a single point is 0.5-1m. 3 / h.

6. The method for repairing the cutterhead during tunnel boring machine excavation as described in claim 1, characterized in that: The method for layered cleaning of the working face and graded fixing of the cutterhead includes: Phase 1: Cleaning the upper empty chamber area of ​​the tunnel face and establishing the first support. Clean the backfill material in the upper 2m range of the shield tunnel soil chamber in area #1. After cleaning, weld the first support platform cross brace, cutterhead #1 fixed steel and #2 fixed steel to the shield tunnel soil chamber wall and cutterhead. At the same time, weld 4 hoist lifting points made of Q355B material to the shield tunnel soil chamber wall and cutterhead. Then clean the backfill material in area #2 of the shield tunnel soil chamber. The second stage involves cleaning the backfill material in areas 3 and 4 within a 1.26m range between the cutterhead and the pile. After completion, the second support platform cross brace, the cutterhead fixed steel section 3, and the cutterhead fixed steel section 4 are welded to form a rigid connection between the cutterhead and the second support platform. The third stage: clean the backfill material in areas 5 and 6 within a 1.26m range between the cutterhead and the pile, and weld the horizontal and vertical supports of the third, fourth, and fifth support platforms in sequence to form a 5-layer stepped support platform system. Phase 4: Clean up Area 7 within 1.26m of the excavation cutterhead and the B-type bored pile using water drills and pneumatic picks. Then clean up the backfill material in Area 8 of the excavation face. Weld the diagonal braces of the first, second, and third support platforms to form a combined support system of horizontal, diagonal, and vertical braces.

7. The method for repairing the cutterhead during tunnel boring machine excavation as described in claim 6, characterized in that: The method of adjusting the cutter head posture by synchronously controlling multiple horizontal thrust cylinders through a hydraulic pump station includes: Four sets of horizontal pushing cylinders are evenly arranged in the circumference of the cutter head, and tilt sensors, pressure sensors and displacement sensors are installed at the ends of the horizontal pushing cylinders. A three-dimensional laser scanner is installed in the circumference of the cutter head, and a strain sensor array is installed on the support platform. Based on the cutterhead design parameters, actual cutterhead detachment measurement parameters, and 3D scanning point cloud data of the shield tunnel soil chamber, a digital twin model of cutterhead-platform-cylinder is constructed. Based on the digital twin model, the attitude adjustment process of the cutterhead from the current attitude to the target attitude is simulated. The initial thrust distribution ratio, action timing and limit displacement threshold of each horizontal pushing cylinder are iteratively optimized to generate the optimal adjustment path. Based on the optimal adjustment path, the adjustment control command is triggered. The horizontal pushing cylinder responds to the adjustment control command, and multiple sets of horizontal pushing cylinders are controlled based on adaptive fuzzy PID control. Multi-source monitoring data are collected in real time, and the multi-source monitoring data are adaptively fused based on the Kalman filter algorithm to output an adaptive fused data stream. The adaptive fused data stream is linearly embedded and position encoded to obtain an encoded data stream. Load the encoded data stream, extract the spatiotemporal fusion features of the encoded data stream through a multi-head self-attention mechanism, perform global credential pooling on the spatiotemporal fusion features, and output the global pose feature vector. Based on the global feature vector recognition analysis of attitude using a dual-branch fully connected regression network, the actual output state of the horizontal pushing cylinder and the current pose of the cutter head are output. The current pose of the cutter head includes the horizontal offset, vertical offset, and rotational deviation. A coupling mapping relationship is established between the output state of the horizontal pushing cylinder and the change of the cutterhead pose. The coupling mapping adopts a residual network structure based on physical priors. The deviation between the target pose of the cutterhead and the current pose of the cutterhead is used as input. By solving the inverse problem of the coupling mapping, the target output increment of each cylinder is generated, and the target output increment is converted into a hydraulic pump station control command.

8. The method for repairing the cutterhead during tunnel boring machine excavation as described in claim 7, characterized in that: The dual-branch fully connected regression network includes a pose regression branch and an output regression branch, with both branches sharing a bottom-level feature extraction layer. The bottom-level feature extraction layer adopts a 5-layer fully connected structure, and the dual-branch fully connected regression network is trained using a transfer learning strategy.

9. The method for repairing the cutterhead during tunnel boring machine excavation as described in claim 8, characterized in that: The method for removing broken wires using welding-assisted extraction or countersinking tapping processes includes: Based on the inspection results upon entering the warehouse, broken wires are classified into three categories according to their fracture morphology: Category I broken wires: the fracture surface is exposed and the thread is not obviously stuck; Category II broken wires: the fracture surface is recessed or the thread is corroded and stuck; Category III broken wires: the root of the broken wire is broken or the thread is stripped. For Class I broken wires, a pneumatic impact wrench is used to directly apply force to the exposed end of the broken wire, using high-frequency impact force to overcome static friction and directly unscrew the broken wire; For Class II broken wires, select a standard hexagonal nut with a nominal diameter 1-2 sizes smaller than the original bolt as the welding base material. Place the nut above the broken wire end face, ensuring that the inner hole of the nut is coaxial with the broken wire. Use a segmented back-welding method to weld a fillet weld from the inside of the nut to the broken wire end face. The weld height should not be less than 0.7 times the nut wall thickness, and the cooling time should not be less than 5 minutes. After welding, use a hydraulic torque wrench or a pneumatic impact wrench to turn the nut and drive the broken wire out as a whole. For Class II process failures or Class III wire breakages, a magnetic drill is used to drill a process hole with a diameter of 80-120mm at the center of the broken wire. The hole depth penetrates the thickness of the cutter head flange and the remaining section of the broken wire. The process hole is then enlarged using a countersunk end mill until the hole diameter is 1-2mm larger than the bolt thread root diameter. The remaining broken wire and rusted threads in the hole are removed. The enlarged hole wall is then tapped with a tap to re-machine a trapezoidal or triangular thread that meets the tolerance requirements, restoring the threaded connection function. After thread repair and processing, once the broken thread is removed or the thread is reconstructed, use a wire brush to clean the iron filings inside the threaded hole, apply molybdenum disulfide grease, and use a go gauge and no-go gauge to inspect the thread accuracy. Only after passing the inspection can a new bolt be installed.

10. The method for repairing the cutterhead during tunnel boring machine excavation as described in claim 9, characterized in that: The method for precisely aligning the cutterhead flange and the drive disc flange includes: The cutter head is moved to the vicinity of the drive disc flange by a horizontal thrust cylinder, and initial alignment is achieved by the cooperation between the outer edge guide cone surface of the cutter head and the corresponding cone surface of the drive disc. Insert 4-6 tapered locating pins between the blade disc flange and the drive disc flange. The diameter of the small end of the locating pin is 2-3mm smaller than the diameter of the bolt hole, and the taper is 1:20-1:

50. The precise concentric positioning of the blade disc and the drive disc is achieved by hammering the locating pins. After the locating pins are installed, insert the connecting bolts according to the diagonal alternation and graded loading principle and tighten them initially. Then, use a hydraulic tensioner or hydraulic torque wrench to tighten them in three progressive stages of 30%-60%-100% of the design value. After each stage of tightening, use a marker to mark the relative position of the bolt head and the flange face.

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