TBM tunnel collapse treatment method

Abstract

The application discloses a TBM tunnel collapse processing method. It aims to solve the problem of TBM equipment protection and escape processing when TBM tunnel collapses and buries TBM under the action of high water and soil pressure. Through geological detection in the advanced geological detection hole of the TBM tunnel face and drilling in the detection hole, water discharge and pressure reduction can be realized at the same time. And through large-scale multi-angle drilling, the mud layer can be penetrated to form an effective water discharge and pressure reduction path. In addition, after water discharge and pressure reduction through the water discharge hole in the TBM tunnel, the geological detection hole and the parallel pilot hole, high-level grouting is carried out through the geological detection hole to realize transverse reinforcement, which can effectively improve the reinforcement stability and reliability of the surrounding rock. In addition, chemical grouting slurry and cement matrix material are respectively injected in different ranges during grouting reinforcement, so as to form a protective ring similar to a grouting pad on the upper part of the TBM equipment by the chemical slurry, and the surrounding rock is reinforced by the cement matrix material, thereby ensuring the safety of the TBM equipment.

Description

Technical Field

[0001] This invention application relates to the field of TBM construction technology, specifically to a method for handling TBM tunnel collapse. Background Technology

[0002] The water-rich granite fracture zone has undergone significant chemical changes due to long-term erosion by fissure water and air. The increase in highly hydrophilic clay minerals such as montmorillonite, chlorite, and illite-montmorillonite has led to increased water volume in the joints and fissures of the rock mass. This water, mixed with alteration materials, softens and lubricates the rock, reducing frictional resistance and stability between rock blocks. The rock mass exhibits very low strength, highly developed weak structural planes, and an extremely fragmented overall structure with poor self-stabilizing ability. Tunnel excavation will inevitably trigger unfavorable geological formations and debris, causing them to flow into the tunnel and create a debris flow-like disaster.

[0003] In a tunnel boring machine (TBM) construction project under adverse geological conditions, a sudden water inrush occurred during TBM excavation in the main tunnel. The inrush water carried a large amount of fine sand and debris, causing debris accumulation at the tunnel bottom. Furthermore, the cutterhead was filled with fragmented debris, and the cutter holes were blocked by fragmented and breccia-like debris. The main lithology was granite interspersed with quartz. The TBM was forced to stop due to the inrush. During the stoppage, the TBM was pushed backward by the surrounding rock at the tunnel face, and the propulsion cylinders had been fully compressed. The backward reaction force at the tunnel face acted on the support system, indicating significant pressure on the surrounding rock at the tunnel face. Intermittent inrushes occurred at the tunnel face, and linear and streaks of water appeared within the shield tail area. In addition, excessive surrounding rock pressure can lead to initial support collapse in the excavated section and the formation of breaches in localized areas, resulting in mudslides and water inrushes.

[0004] Due to the complex and variable geological environment and high water and soil pressure around the working face, the existing surface drainage and advanced grouting reinforcement methods cannot effectively extricate the TBM from its predicament.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the background technology of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] In view of at least one of the above technical problems, this disclosure provides a method for handling TBM tunnel collapse, which aims to solve the problem of protecting and freeing TBM equipment when a TBM tunnel collapses and buries the TBM under high water and soil pressure.

[0007] According to one aspect of this disclosure, a method for handling TBM tunnel collapse is provided, comprising the following steps: (1) Set up a parallel guide tunnel on one side of the main tunnel, and drill several parallel guide drainage holes in the parallel guide tunnel toward the main tunnel; and open a pipe roof workshop within 180° circumferential range of the arch shield of the main tunnel, and drill several advanced drainage holes toward the working face within 180° range of the arch of the pipe roof workshop. (2) Grouting reinforcement of the pipe roof is carried out in the pipe roof working room, and small pipes with an external insertion angle of not less than 40° are cyclically installed within 180° of the arch of the main tunnel. (3) After the slag in the main tunnel is reinforced, the lower step is excavated. During the excavation of the step, grouting pipes are laid down at an angle to the upper step for grouting reinforcement. After the slag is excavated, the initial support structure including the steel frame support is replaced. A grid steel frame is set up on the inner side of the initial support structure to form a concrete arch wall and a grouting pipe is pre-embedded before the secondary lining is constructed. (4) Drill several advanced geological boreholes at the tail arch of the shield, and conduct TSP surveys at the face of the tunnel. Also, set up geological exploration tunnels on one side of the main tunnel along the tunneling direction. (5) Drill several drainage holes on the left and right sides of the tunnel arch and the tunnel bottom shield tail at the corresponding positions behind the advanced geological borehole; first drill drainage holes perpendicular to the working face and parallel to the working face respectively, and then adjust the drilling angle of the drainage holes according to the obstruction of the drilling of the drainage holes; and determine the adverse geological boundary in conjunction with step (4). (6) After the water is drained and the working face is stabilized, small guide pipes and / or glass fiber pipes are driven into the working face within a 120° range of the shield tail arch for shallow hole grouting reinforcement; glass fiber anchor bolts are used for advance grouting reinforcement of the working face and the surrounding area inside the cutterhead. (7) High-level grouting shall be carried out from the geological exploration tunnel toward the main tunnel, and the radial reinforcement of the high-level grouting shall be no less than the range corresponding to 8m outside the excavation outline of the main tunnel; (8) Drill several radial exploratory holes with a depth of not less than 3m at the arch position corresponding to the rear of the shield tail; (9) Open a small guide hole at the shield tail arch to the front of the cutterhead and excavate in a circumferential manner to release the shield.

[0008] In some embodiments of this disclosure, in step (1), a guide wall is provided at the end face of the working face corresponding to the pipe shed studio, and a steel frame is provided inside the guide wall; the pipe shed studio is supported by steel shotcrete.

[0009] In some embodiments of this disclosure, in step (1), two rings of advanced drainage holes are drilled, with the elevation angles of the two rings of advanced drainage holes being 10-15° and 20-25°, respectively.

[0010] In some embodiments of this disclosure, in step (2), the grouting material for the pipe roof includes cement grout with a water-cement ratio of 0.6:1 to 1:1, cement-water glass double-liquid grout with a volume ratio of 1:0.6 to 1:1, and polyurethane chemical grout; and the pipe roof is grouted in a forward-moving manner, with polyurethane chemical grout injected within at least 5m in front of the tunnel face, and cement grout and / or double-liquid grout injected in the remaining area.

[0011] In some embodiments of this disclosure, in step (3), drainage boards are provided between the initial support and the grid steel frame cast concrete arch wall, and between the grid steel frame cast concrete arch wall and the secondary lining; the side of the grouting pipe close to the surrounding rock is tightly attached to the surrounding rock, and radial grouting is performed on the surrounding rock through the grouting pipe before the secondary lining. After the secondary lining, the grouting pipe is cleaned to make radial drainage holes.

[0012] In some embodiments of this disclosure, in step (4), advanced geological boreholes with an elevation angle of 15 to 20° are drilled at positions 11, 12, 1 and 2 of the shield tail arch.

[0013] In some embodiments of this disclosure, in step (5), at least three drainage holes with an elevation angle of 20 to 25° are drilled corresponding to the tunnel arch; the drainage holes on the left and right sides of the tunnel bottom shield tail have an elevation angle of 10 to 15°.

[0014] In some embodiments of this disclosure, in step (7), several drainage holes are set above the high-level grouting hole before high-level grouting.

[0015] One or more technical solutions provided in the embodiments of this application have at least one of the following technical effects or advantages: 1. By conducting geological exploration ahead of the TBM working face through a geological exploration tunnel and drilling inside the tunnel, water drainage and pressure reduction can be achieved simultaneously.

[0016] 2. Due to severe alteration and mudification caused by adverse geological conditions, large-scale, multi-angle drilling can penetrate the mud layer to form an effective drainage and pressure reduction path.

[0017] 3. After depressurization through drainage holes, geological exploration tunnels, and parallel pilot tunnels inside the TBM tunnel, high-level grouting is then carried out through the geological exploration tunnel to achieve lateral reinforcement, which can effectively improve the reinforcement stability and reliability of the surrounding rock.

[0018] 4. During grouting reinforcement, chemical grout and cement matrix material are injected into different areas respectively. The chemical grout forms a protective ring similar to a grout-stopping pad on the upper part of the TBM equipment, while the cement matrix material achieves the purpose of surrounding rock reinforcement, thereby ensuring the safety of the TBM equipment and avoiding damage. Attached Figure Description

[0019] Figure 1 This is a layout diagram of the parallel pilot tunnel and geological exploration tunnel in one embodiment of this application.

[0020] Figure 2 This is a schematic diagram of the cross-sectional layout of the parallel guide tunnel drainage holes in one embodiment of this application.

[0021] Figure 3 This is a schematic diagram of the cross-sectional layout of the pipe shed working chamber in one embodiment of this application.

[0022] Figure 4 This is a schematic diagram of the layout of high-level grouting holes according to an embodiment of this application.

[0023] Figure 5 This is a schematic diagram of a high-level grouting section according to an embodiment of this application.

[0024] In the above figures, 1 is the parallel pilot tunnel, 2 is the main tunnel, 3 is the geological exploration tunnel, 4 is the boundary of unfavorable geological conditions, 5 is the horizontal pilot drainage hole, 6 is the pipe roof working chamber, and 7 is the high-level grouting hole. Detailed Implementation

[0025] To better understand the technical solution of this application, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] To effectively protect TBM equipment and reasonably and safely handle the collapsed material after a TBM tunnel collapse, this example discloses a method for handling TBM tunnel collapses, which specifically includes the following steps: (1) Set up a parallel guide tunnel on one side of the main tunnel, and drill several horizontal guide drainage holes in the parallel guide tunnel toward the main tunnel; and open a pipe roof workshop within 180° circumferential range of the arch shield of the main tunnel, and drill several advanced drainage holes in the 180° range of the arch of the pipe roof workshop toward the working face.

[0027] This example illustrates a tunnel construction project under adverse geological conditions. During excavation, a sudden gush of turbid water, carrying gravel and fine slag, erupted from the left side of the TBM support shoe. Half an hour later, the entire excavated section experienced turbid, stream-like water discharge carrying slag. Simultaneously, abnormal noises were observed from the steel frame, the reinforcing bars bent, the arch steel frame began to sink and twist, and the already cast concrete section began to crack and peel off, extending towards the tunnel entrance. To address this, temporary support was provided by adding vertical bracing between the tunnel arch and the working platform. To prevent the working platform from sinking under pressure, additional vertical bracing was added between the main beam and the working platform, as well as between the tunnel floor and the main beam. The rear supports were then welded with limiting mechanisms. Specifically, dense HW150 steel vertical bracing, diagonal bracing, and counter-bracing were added above the working platform. HW150 steel or steel pipes were used to support the main beam, the working platform, and the area below the main beam, with longitudinal connections between the bracing elements reinforced. In addition, in this case, steel pipes, square timber, and bagged cement were stacked throughout the tunnel from the tail of the shield to the tail of the deformation section to add escape routes; backfilling work was carried out while adding support.

[0028] Once the site is stable and free of abnormalities, to prevent long-term blockage of the TBM equipment by mud and water due to clogging in the deformation area, the slag is gradually cleared and backfilled towards the working face, while retaining the supports. Considering the water-rich and high-pressure environment under adverse geological conditions, in this embodiment, drainage operations are carried out before slag clearing, dismantling, and backfilling.

[0029] Specifically, in this embodiment, see Figure 1 A parallel pilot tunnel was constructed on one side of the main tunnel. The parallel pilot tunnel was excavated through the alteration zone. (See [reference]). Figure 2 A φ130mm horizontal guide drainage hole is drilled in the parallel guide tunnel towards the main tunnel. In this example, the horizontal guide drainage hole is 35m long and the longitudinal interval is 2m. The horizontal guide drainage hole assists in the drainage of water within the main tunnel area.

[0030] To achieve pressure relief and reinforcement of unfavorable geological conditions, in this example, see... Figure 3A pipe roof workstation was constructed within a 180° circumferential range of the tunnel arch shield, with an excavation height of 2.5m. The workstation was supported by steel-framed shotcrete, with HW150 steel frames spaced 0.9m longitudinally. Adjacent steel frames and supports were connected longitudinally with HW100 steel frames spaced 1m circumferentially, and sealed with 20cm thick C25 shotcrete. Additionally, a 0.5m thick, 180° circumferentially high C25 concrete guide wall was constructed at the end face of the pipe roof workstation corresponding to the tunnel face. To ensure the guide wall's stability and safety, four HW100 steel frames were installed within it, spaced 0.4m longitudinally and 0.3m vertically. Thus, by placing the guide wall close to the tunnel face, it served as a guide and anchoring facility for long pipe roof construction, providing both guidance and support for the pipe roof, and improving its stress distribution. The steel frame installed inside the guide wall is used to install the guide pipe for the pipe shed. The precise determination of the guide pipe angle ensures the accuracy of the subsequent pipe shed angle, and at the same time plays a role in supporting the pipe shed and improving the stress on the pipe shed.

[0031] However, considering the water-rich characteristics of the unfavorable geological body, in order to drain groundwater above the tunnel, reduce surrounding rock pressure, and ensure the effectiveness of subsequent grouting reinforcement, this example involves drilling two rings of eight φ130mm pre-drainage holes within a 180° radius of the arch of the excavated pipe roof working chamber, extending towards the tunnel face. The elevation angles are 15° and 20° respectively, with a circumferential spacing of 1m between each ring of holes, and a hole length of 35m. In other embodiments, the elevation angle of the pre-drainage holes is selected from other angles within the range of 10-15° and 20-25°, depending on the tunnel conditions. Thus, groundwater drainage is initially achieved through the guide drainage holes and pre-drainage holes.

[0032] (2) Grouting reinforcement of pipe roof is carried out in the pipe roof working room, and small pipe advanced support with an external insertion angle of not less than 40° is carried out cyclically within 180° of the arch of the main tunnel.

[0033] After effective drainage is achieved, pipe roof grouting reinforcement is carried out. In this embodiment, a double-layer pipe roof is installed. The inner ring pipe roof is installed within a 160° range of the arch, and the outer pipe roof is installed within a 125° range to the right of the arch. The pipe roof is 45m long and consists of 95 pipes. Specifically, the outer pipe roof is installed from 80° to the right of the arch crown to 45° to the left of the arch crown, with both the inner and outer pipe roofs installed facing forward of the tunnel face. During this process, the pipe roof boreholes can also serve as geological exploration boreholes. Based on the geological conditions revealed by the boreholes, it is determined whether to install advanced pipe roofs from the left arch waist to the arch foot to improve the rigidity of the advanced support pipe roofs and increase their resistance to surrounding rock pressure.

[0034] In this embodiment, the pipe roof orifice pipe is made of hot-rolled seamless steel pipe with an outer diameter of 108mm, a wall thickness of 6mm, and a circumferential center-to-center spacing of 30cm. The orifice pipe is constructed parallel to the centerline of the pipeline, with the external insertion angle controlled within 3°. The pipe roof itself is made of hot-rolled seamless steel pipe with an outer diameter of 76mm, a wall thickness of 4mm, and a circumferential center-to-center spacing of 30cm. Furthermore, in this example, the grouting materials for the pipe roof include cement grout with a water-cement ratio of 0.6:1 to 1:1, cement-water glass double-liquid grout with a volume ratio of 1:0.6 to 1:1, and water-blocking and reinforcing polyurethane chemical grouts. During pipe roof construction, a forward grouting method is used. To protect the TBM equipment area, polyurethane chemical grout is injected within 5m in front of the tunnel face, and cement grout or double-liquid grout is injected in the remaining area. The ratio of double-liquid grout to cement grout is 3:7, and the grouting filling rate is 10%.

[0035] After the pipe roof grouting reinforcement is completed, φ42 small guide pipes with a large outward insertion angle are cyclically installed within a 180° range of the tunnel arch. These small guide pipes are φ42 pipes installed within a 180° range of the tunnel arch, each 5m long, with a circumferential spacing of 0.4m, an outward insertion angle of 45°, and a cyclic installation length of 2m. Similarly, polyurethane chemical grout is injected within the first 5m range, and 1:0.6 to 1:1 cement grout is injected into the remaining range.

[0036] (3) After the slag in the main tunnel is reinforced, the lower step is excavated. During the excavation of the step, grouting pipes are laid down at an angle to the upper step for grouting reinforcement. After the slag is excavated, the initial support structure including the steel frame support is replaced. A grid steel frame is set up on the inner side of the initial support structure to form a concrete arch wall and a grouting pipe is pre-embedded before the secondary lining is constructed.

[0037] After drainage and pipe roof reinforcement, the debris removal operation was carried out. In this case, the left side of the tunnel was filled with collapsed debris, located precisely at the location of the propulsion cylinder, main bearing, and support shoe cylinder. Therefore, grouting reinforcement was first performed on the debris. φ42mm steel pipes were used for grouting, with a depth of 6m and a circumferential length of 8m. Since the area requiring reinforcement was below the work platform, the grouting pipes were installed at a downward angle from the upper step to ensure effective grouting reinforcement of the area. Polyurethane chemical grout was used for this section. After grouting reinforcement, the collapsed debris was excavated using a step-by-step method, with gradual grouting and excavation to restore the initial support structure of the main tunnel TBM. Furthermore, in this case, the right side of the main tunnel did not collapse; therefore, φ42mm steel pipes with a depth of 6m and a circumferential length of 8m were used for cement-water glass double-liquid grout reinforcement.

[0038] After the slag heap is excavated, the initial support structure is replaced based on its deformation. Considering the inability to construct secondary lining in a timely manner, and to ensure the initial support can withstand the long-term load of the surrounding rock, this embodiment employs a structure combining the initial support with a reinforced concrete arch wall. The initial support consists of a full-ring HW150 steel frame reinforced with a spacing of 0.45m per frame and a shotcrete thickness of 22cm. A 60cm thick C30 steel frame reinforced concrete arch wall is installed at the edge of the initial support, with four-limb steel frame reinforcement skeletons spaced 60cm apart on both sides. These reinforcement skeletons are prefabricated outside the tunnel and installed on-site inside, with all components welded together. Thus, the full-ring HW150 steel frame serves as the initial support on the outermost side, while the steel frame reinforced concrete arch wall serves as the reinforcement, ensuring the reliability and safety of the support. Later, a secondary lining was constructed outside the cast-in-place concrete of the grid steel frame. The secondary lining adopted Class V surrounding rock type B composite lining, which is C35 reinforced concrete with a thickness of 35cm.

[0039] In this embodiment, φ100mm PVC grouting pipes are pre-embedded radially within the initial support and the grid-cast concrete arch wall, spaced 1m*1m (circular*longitudinal) in a staggered pattern, with a length of approximately 1.5m. The end of the grouting pipe closest to the surrounding rock surface is pressed tightly against the rock. Thus, before the secondary lining is constructed, radial grouting is performed on the surrounding rock using the pre-embedded grouting pipes, with a grouting reinforcement ring thickness of 5m. This prevents the drainage water before the secondary lining construction from carrying away fine particles from the surrounding rock, which could lead to voids behind the initial support. The voids are filled by supplementary grouting through the grouting pipes.

[0040] In addition, in this embodiment, concave-convex drainage boards are provided between the initial support and the grid steel frame cast-in-place concrete arch wall, and between the grid steel frame cast-in-place concrete arch wall and the subsequent secondary lining. The convex side of the drainage board is closely attached to the initial support or the grid steel frame cast-in-place concrete arch wall. After the radial grouting reinforcement is completed, the grouting hole is swept open again, and radial drainage holes with a depth of 8m are made. In conjunction with the drainage board, the groundwater is finally introduced into the tunnel side ditch for discharge.

[0041] (4) Drill several advanced geological boreholes at the tail arch of the shield, conduct TSP surveys at the face of the tunnel, and set up geological exploration tunnels on one side of the main tunnel along the tunneling direction.

[0042] To identify the boundaries of unfavorable geological conditions and further reduce water pressure, in this embodiment, advanced geological boreholes with an elevation angle of 15-20° and a depth of 30m are drilled at positions 11, 12, 1, and 2 corresponding to the shield tail arch above the TBM main beam. These advanced geological boreholes serve to identify the boundaries of unfavorable geological conditions and also facilitate water pressure reduction. In this embodiment, to accurately identify the boundaries of unfavorable geological conditions, TSP geophysical exploration is conducted at the tunnel face after the advanced geological boreholes are drilled, and this is combined with surface surveys as a basis for judgment.

[0043] In addition, a geological exploration tunnel, 50m long, was set up on the left side of the main tunnel excavation direction, corresponding to 15m in front of the tunnel face. See [link / reference needed]. Figure 1 This allows for geological assessments to be made based on the surrounding rock conditions revealed during the excavation of the geological exploration tunnel. Furthermore, since the geological exploration tunnel is ahead of the trapped TBM, long-distance boreholes can be drilled in the geological exploration tunnel parallel to the main tunnel excavation direction to continue geological exploration.

[0044] (5) Drill several drainage holes on the left and right sides of the tunnel arch and the shield tail at the corresponding position behind the advanced geological borehole; first drill drainage holes perpendicular to the working face and parallel to the working face respectively, and then adjust the drilling angle of the drainage holes according to the obstruction of the drilling; and determine the adverse geological boundary in conjunction with step (4).

[0045] In this example, at least three drainage holes with an elevation angle of 20–25° are drilled in the tunnel arch; the drainage holes on the left and right sides of the tunnel bottom shield tail have an elevation angle of 10–15°. By placing the drainage holes behind the advanced geological boreholes, the height of the borehole from the cutterhead is higher when the drilling position reaches the trapped face, which can achieve high-level drainage and verify the geological conditions at the high level. During the drilling process of the drainage holes, drilling is first carried out perpendicular to the face. When drilling is obstructed, drilling is then carried out parallel to the face. After the drilling is normal and water is produced, drilling is gradually shifted towards the direction perpendicular to the face to gradually explore the adverse geological environment.

[0046] In this case, advanced geological drilling revealed that the adverse geological conditions were mainly concentrated in front of and to the right of the tunnel face. The boreholes showed signs of pressure failure to penetrate, and some boreholes intermittently experienced mud and water inflow. Through drainage holes and geological exploration tunnels, it was revealed that the overall adverse geological conditions were developing from right to left, with a planar width of approximately 40m and a length of approximately 64m.

[0047] (6) After the water is drained and the working face is stable, small guide pipes and / or glass fiber pipes are driven into the working face within a 120° range of the shield tail arch for shallow hole grouting reinforcement; glass fiber anchor bolts are used for advance grouting reinforcement of the working face and the surrounding area inside the cutterhead.

[0048] In this example, small guide pipes are used for shallow hole grouting reinforcement. In other embodiments, due to the relative difficulty of drilling, fiberglass tubes are used to achieve shallow hole grouting reinforcement. In this example, the circumferential spacing of the small guide pipes is 0.5m, the external insertion angle is 16°~20°, the reinforcement depth is 7m, and the grouting material is polyurethane chemical grout. Thus, by reinforcing the arch within a 120° range with polyurethane chemical material, the stability of the surrounding rock is ensured, providing excavation conditions for the subsequent excavation shield to escape.

[0049] In addition, after the overall water discharge from the rear drainage section stabilized and the tunnel face was basically stable, advanced grouting reinforcement was carried out inside the cutterhead for the tunnel face and surrounding area. The reinforcement range was 3m to 5m, the grouting pipe was a fiberglass anchor rod, and the grouting material was a polyurethane chemical material.

[0050] (7) High-level grouting shall be carried out from the geological exploration tunnel toward the main tunnel. The radial reinforcement of the high-level grouting shall be no less than the range corresponding to 8m outside the excavation outline of the main tunnel.

[0051] See Figure 4 and Figure 5 In this embodiment, high-level grouting reinforcement is carried out by drilling holes on the inner side of the geological exploration tunnel and at the tunnel face towards the main tunnel TBM. The reinforcement range along the radial direction of the main tunnel is 8m outside the excavation outline. In this example, the excavation outline is controlled at 8m outside the right arch wall of the line. The high-level grouting adopts the forward curtain grouting method, with a total of 18 rows and 99 grouting holes. Nine rows are arranged in a quincunx pattern on the inner side of the geological exploration tunnel and at the tunnel face. The spacing between the bottom of the horizontal grouting holes is controlled at 3.0-3.5m, and the spacing between the bottom of the vertical grouting holes is controlled at 3.7m. The grout material for the high-level grouting holes is polyurethane chemical grout, and the grouting material for the other holes is 0.6:1 to 1:1 cement grout and 1:0.6 to 1:1 cement-water glass double-liquid grout. The opening and sealing holes use double-liquid grout. The grouting filling rate is 10%, the grouting pressure is 2-3MPa, and the grout diffusion radius is 2.0m.

[0052] To ensure effective grouting and pre-emptive drainage of groundwater, two rows of φ130mm drainage holes, each 30m long and spaced 1m apart laterally, are installed above the high-level grouting holes in this embodiment before the high-level grouting. Furthermore, in this embodiment, high-level grouting of the geological exploration tunnel and pipe roof grouting are initiated simultaneously.

[0053] (8) Drill several radial exploratory holes with a depth of not less than 3m at the arch position corresponding to the rear of the shield tail; In this embodiment, considering that the drilling risk of the rear drainage and the exploratory borehole after the face is stabilized is low, in order to detect whether there are loose and broken bodies behind the initial support, radial exploratory boreholes are drilled at the arch position within 10m behind the shield tail, with a detection depth of not less than 3m and a longitudinal spacing of 2m. Accordingly, reinforcement measures are taken based on the detection results.

[0054] (9) Open a small guide hole at the shield tail arch to the front of the cutterhead and excavate in a circumferential manner to release the shield.

[0055] In the aforementioned steps, fiberglass anchors were installed at the cutterhead cutter holes and slag scraper openings to reinforce the tunnel face with advanced chemical grouting. In order to enable the TBM to escape, a small guide hole was opened at the shield tail arch to the front of the cutterhead and the shield was released by circumferential 180° excavation. The excavation height was 1.5m, and the support was made of HW150 steel with a spacing of 0.9m. C25 concrete was sprayed with a thickness of 20cm.

[0056] During the pipe roof construction, a total of 1107m of φ76 steel pipe was laid, 83.32m³ of polyurethane chemical grout was injected, and 114.64m³ of cement grout was injected. The grouting volume in the adverse geological conditions was approximately 2140m³, with an actual total grouting volume of 197.96m³, resulting in a back-calculated filling rate of 9.3%. Three verification holes were drilled simultaneously, with good drilling results and no sand or mud inflow. The initial water inflow at the working face was approximately 150m³ / h, which decreased to 40m³ / h after the drainage holes were installed. Facing the adverse geological environment of weak, fractured, high-pressure, and water-rich surrounding rock, the treatment and extrication of the TBM collapse area were completed in 7.2 months using the above methods.

[0057] Although some preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0058] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of its inventive concept. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for handling TBM tunnel collapse, characterized in that, Includes the following steps: (1) Set up a parallel guide tunnel on one side of the main tunnel, and drill several parallel guide drainage holes in the parallel guide tunnel toward the main tunnel; and open a pipe roof workshop within 180° circumferential range of the arch shield of the main tunnel, and drill several advanced drainage holes toward the working face within 180° range of the arch of the pipe roof workshop. (2) Grouting reinforcement of the pipe roof is carried out in the pipe roof working room, and small pipes with an external insertion angle of not less than 40° are cyclically installed within 180° of the arch of the main tunnel. (3) After the slag in the main tunnel is reinforced, the lower step is excavated. During the excavation of the step, grouting pipes are laid down at an angle to the upper step for grouting reinforcement. After the slag is excavated, the initial support structure including the steel frame support is replaced. A grid steel frame is set up on the inner side of the initial support structure to form a concrete arch wall and a grouting pipe is pre-embedded before the secondary lining is constructed. (4) Drill several advanced geological boreholes at the tail arch of the shield, and conduct TSP surveys at the face of the tunnel. Also, set up geological exploration tunnels on one side of the main tunnel along the tunneling direction. (5) Drill several drainage holes on the left and right sides of the tunnel arch and the tunnel bottom shield tail at the corresponding positions behind the advanced geological borehole; first drill drainage holes perpendicular to the working face and parallel to the working face respectively, and then adjust the drilling angle of the drainage holes according to the obstruction of the drilling of the drainage holes; and determine the adverse geological boundary in conjunction with step (4). (6) After the water is drained and the working face is stabilized, small guide pipes and / or glass fiber pipes are driven into the working face within a 120° range of the shield tail arch for shallow hole grouting reinforcement; glass fiber anchor bolts are used for advance grouting reinforcement of the working face and the surrounding area inside the cutterhead. (7) High-level grouting shall be carried out from the geological exploration tunnel toward the main tunnel, and the radial reinforcement of the high-level grouting shall be no less than the range corresponding to 8m outside the excavation outline of the main tunnel; (8) Drill several radial exploratory holes with a depth of not less than 3m at the arch position corresponding to the rear of the shield tail; (9) Open a small guide hole at the shield tail arch to the front of the cutterhead and excavate in a circumferential manner to release the shield.

2. The TBM tunnel collapse treatment method according to claim 1, characterized in that, In step (1), a guide wall is set at the end face of the pipe shed working face corresponding to the working face, and a steel frame is set inside the guide wall; the pipe shed working face is supported by steel shotcrete.

3. The TBM tunnel collapse treatment method according to claim 1, characterized in that, In step (1), two rings of advanced drainage holes are drilled, with elevation angles of 10-15° and 20-25° corresponding to the two rings of advanced drainage holes.

4. The TBM tunnel collapse treatment method according to claim 1, characterized in that, In step (2), the grouting materials for the pipe roof include cement grout with a water-cement ratio of 0.6:1 to 1:1, cement-water glass double-liquid grout with a volume ratio of 1:0.6 to 1:1, and polyurethane chemical grout; and the pipe roof is grouted in a forward manner, with polyurethane chemical grout injected within at least 5m in front of the tunnel face, and cement grout and / or double-liquid grout injected in the remaining area.

5. The TBM tunnel collapse treatment method according to claim 1, characterized in that, In step (3), drainage boards are provided between the initial support and the grid steel frame cast concrete arch wall, and between the grid steel frame cast concrete arch wall and the secondary lining. The side of the grouting pipe closest to the surrounding rock is closely attached to the surrounding rock. Before the secondary lining, radial grouting is performed on the surrounding rock through the grouting pipe. After the secondary lining, the grouting pipe is cleaned to make corresponding radial drainage holes.

6. The TBM tunnel collapse treatment method according to claim 1, characterized in that, In step (4), advanced geological boreholes with an elevation angle of 15 to 20° are drilled at positions 11, 12, 1 and 2 of the shield tail arch.

7. The TBM tunnel collapse treatment method according to claim 1, characterized in that, In step (5), at least three drainage holes with an elevation angle of 20 to 25° are drilled in the tunnel arch; the drainage holes on the left and right sides of the tunnel bottom shield tail have an elevation angle of 10 to 15°.

8. The TBM tunnel collapse treatment method according to claim 1, characterized in that, In step (7), several drainage holes are set above the high-level grouting hole before high-level grouting.

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