Construction method for repairing shield tunnel

Abstract

The invention discloses a construction method for repairing a shield tunnel, which comprises the following steps: S1, carrying out emergency treatment on tunnel collapse, and controlling the tunnel collapse and submerging range; s2, selecting a new tunnel line to avoid the original collapsed tunnel, and fitting a section tunnel flat and vertical section line; s3, an open cut vertical shaft is arranged in the tunnel collapse area, an open cut method is adopted for construction, excavation is conducted step by step, and a supporting structure is erected step by step; s4, the open cut vertical shaft is connected with the intact shield tunnel; s5, carrying out obstacle clearing processing on underground obstacles; s6, when the open cut vertical shaft is constructed, a shield tunneling machine is newly started at the receiving end of the tunnel, and construction is conducted according to a new line of the tunnel; and S7, after open cut shaft construction is completed, a new starting shield tunneling machine is received, and repairing of the whole shield tunnel is completed. According to the method, on the basis that the existing tunnel is fully utilized, ex-situ repair of the collapsed tunnel can be rapidly and economically achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of shield tunnels, and particularly relates to a construction method for repairing shield tunnels. Background Art

[0002] At present, with the rapid development of domestic rail transit and in various cross-river tunnel projects, the shield tunneling method has an increasing proportion in tunnel projects due to its advantages such as high speed, high safety, and little impact. Especially in water-rich soft soil and sandy soil strata, such strata have characteristics such as high confined water head and strong formation permeability, and shield tunnels are often the first choice for tunnel construction methods. During tunnel construction, various construction links are highly risky, and a slight mistake will cause serious consequences. Especially in water-rich soft soil or sandy layers, the rich groundwater and granular sandy soil in the strata require high safety for tunnel construction.

[0003] With the wide application of shield tunnels in China, safety construction accidents of shield tunnels caused by various reasons emerge in an endless stream. In severe cases, it can cause the collapse and abandonment of the entire tunnel, posing a great safety impact on the surrounding environment and buildings.

[0004] During the construction of shield tunnels in water-rich and sand-rich geological conditions, due to various reasons, the high confined water outside is likely to penetrate the sealing brush at the tail of the shield machine, resulting in the influx of external sandy soil and groundwater into the shield machine. When the sealing brush is not blocked in time, the external sandy soil and groundwater will flood the entire shield machine and the previously completed shield tunnel, and the ground will collapse due to soil erosion above the tunnel. Among them, some tunnels collapse due to soil erosion and uneven stress around, resulting in the collapse of the upper part of the tunnel structure, which further causes the ground to collapse.

[0005] Tunnel engineering is a high-risk underground project. Different from ground engineering, tunnel engineering has characteristics such as irreversibility and difficulty in repair. After the collapse of some shield tunnels in water-rich soft soil or sandy layers, due to the uniqueness of the line, there are characteristics such as high cost and long construction period for engineering repair. If in-situ repair is adopted, there are characteristics such as large excavation depth, wide excavation range, and many underground obstacles for open-cut tunnels, and it is easily restricted by various surrounding buildings. On the premise of meeting the design of rail transit lines, the alternative repair plan of building a new bypass tunnel becomes the preferred plan, especially in projects with large burial depth, tight construction period, and limited site conditions.

[0006] In the existing public technologies, a construction method for repairing the collapse of a shield tunnel with the publication number CN118242106A is proposed. Its main content includes setting a section of open-cut tunnel after winding between the starting end of the tunnel and the collapsed area of the tunnel to connect to the starting shield machine at the receiving end of the tunnel. The length of the open-cut tunnel in this technology is relatively large and is suitable for the case where the distance between the collapsed area of the shield tunnel and the starting end of the tunnel is small. When the distance between the collapsed area of the shield tunnel and the starting end of the tunnel is large and the tunnel burial depth is large, if the open-cut tunnel scheme is still adopted, it will greatly increase the open-cut difficulty, project quantity, and investment. Therefore, it is necessary to study a more economical and less risky repair method. Summary of the Invention

[0007] The present invention is proposed to solve the above deficiencies, aiming to provide a construction method for repairing a shield tunnel. Based on making full use of the existing tunnel, this method can quickly and economically achieve the off-site repair of the collapsed tunnel.

[0008] To achieve the above objectives, the present invention adopts the following solutions:

[0009] A construction method for repairing a shield tunnel includes the following steps:

[0010] S1: Carry out emergency treatment on the tunnel collapse to control the scope of tunnel collapse and flooding;

[0011] S2: Select a new tunnel route to avoid the original collapsed tunnel and fit the horizontal and vertical section lines of the interval tunnel;

[0012] S3: Set up an open-cut shaft in the tunnel collapse area, construct by the open-cut method, gradually excavate, and gradually erect the support structure;

[0013] S4: Connect the open-cut shaft to the intact shield tunnel;

[0014] S5: Clear the underground obstacles;

[0015] S6: While constructing the open-cut shaft, newly start a shield machine at the receiving end of the tunnel and construct according to the new tunnel route;

[0016] S7: After the construction of the open-cut shaft is completed, receive the newly started shield machine to complete the repair of the entire shield tunnel.

[0017] As a preferred implementation manner, in step S1, the emergency treatment of the tunnel collapse is specifically as follows: construct a plain concrete or reinforced concrete sealing wall at a set safety distance from the collapse point; after the collapse is stable, vertically drill holes on the ground for grouting to fill the shield tunnel and the shield machine.

[0018] As a preferred implementation manner, in step S3, the support structure of the open-cut shaft includes a diaphragm wall and multiple internal supports.

[0019] As a preferred embodiment, in step S3, when excavating the shaft support structure in a trench above the existing tunnel, the inside of the existing tunnel is backfilled densely with plain concrete or reinforced concrete, and the width is not less than 3 m; when excavating the diaphragm wall trench, a geological drill or a full-rotation full-casing drill is used to pass through the existing intact shield tunnel.

[0020] As a preferred embodiment, in step S4, the connection between the open-cut shaft and the intact shield tunnel is specifically as follows: the soil between the open-cut shaft and the intact shield tunnel is frozen and reinforced.

[0021] As a preferred embodiment, in step S4, the freezing reinforcement is carried out by vertical ground freezing reinforcement or horizontal in-tunnel freezing.

[0022] As a preferred embodiment, in step S5, when removing underground obstacles, a full-casing full-rotation drill is used for ground cleaning, and the underground obstacles within the casing range are removed and then backfilled with concrete; the casings constructed successively form an overlap within the range of 100 - 150 mm to complete the removal of all underground obstacles.

[0023] As a preferred embodiment, in step S6, after the construction of the open-cut shaft is completed, the lower half of the open-cut shaft is backfilled with plain concrete.

[0024] As a preferred embodiment, in step S6, when the newly built shield tunneling machine enters the backfilled open-cut shaft, secondary grouting is carried out multiple times on the segment grouting holes to seal the soil around the segments.

[0025] As a preferred embodiment, in step S6, after the soil around the segments is sealed, the local concrete backfill is excavated, the shield tunneling machine is hoisted out, and after casting the in-situ circular tunnel, the entire open-cut shaft is backfilled, and the repair of the entire shield tunnel is completed.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] First, the present invention solves the problem of repairing tunnel collapses under complex geological environment conditions. When a shield tunnel in water-rich soft soil or sandy layer collapses, in-situ repair has the characteristics of high cost and long construction period. Therefore, it is necessary to study a method for quickly and economically repairing collapsed shield tunnels, that is, selecting an alternative repair plan of constructing a new bypass tunnel. The various methods in this invention have the characteristics of fast construction speed and high engineering quality guarantee. In addition, this technology is not limited to the rail transit industry, but can also be used in the repair projects of shield tunnels in the municipal, highway, water conservancy and other industries.

[0028] Second, in the emergency treatment stage of the present invention, a plain concrete or reinforced concrete plugging wall is quickly built outside the safe distance from the collapse point to form a physical isolation barrier, control the spreading range of the collapse, prevent secondary disasters, and create a closed space condition for subsequent grouting reinforcement. By using vertical ground drilling to grout and fill the shield tunnel and the shield machine, the soil around the collapse can be reinforced, and the stability of the tunnel structure can be improved.

[0029] Third, the construction of the present invention adopts the open-cut shaft method, and only excavates in a local area, with less impact on surface buildings and traffic facilities. Compared with the open-cut tunnel scheme, the open-cut difficulty, engineering quantity, and investment will be greatly reduced, and the collapsed shield tunnel can be repaired quickly and economically.

[0030] Fourth, the present invention sets an open-cut shaft in the collapse area and freezes and reinforces the soil between the open-cut shaft and the intact shield tunnel, which can effectively control the surface settlement and prevent adverse effects on the surrounding environment and buildings.

[0031] Fifth, when the shield machine advances into the interior of the backfilled open-cut shaft, multiple secondary groutings are carried out through the segment grouting holes to plug the soil around the segments and prevent water and soil from seeping into the tunnel, ensuring the safety of the construction process.

[0032] Sixth, while constructing the open-cut shaft, the present invention restarts the shield machine at the tunnel receiving end and advances according to the new route, realizing parallel operation of multiple processes, shortening the construction period, and improving the construction efficiency.

[0033] Seventh, during the construction of the open-cut shaft, when forming a trench above the existing tunnel, the geological drilling rig or the full-rotation full-casing drilling rig process is used to pass through the existing intact shield tunnel, avoiding damage to the existing tunnel structure and ensuring the safety of the existing tunnel.

[0034] Eighth, the present invention uses a full-casing full-rotation drilling rig for ground obstacle clearance, which can accurately remove underground obstacles to ensure that there are no obstacles affecting the shield machine during the propulsion process; the casing overlapping method (within the range of 100 - 150 mm) is used to ensure the complete removal of obstacles and prevent omission problems during construction. Description of the Drawings

[0035] Figure 1 is the plan layout diagram for tunnel collapse repair;

[0036] Figure 2 is the longitudinal section layout diagram for tunnel collapse repair;

[0037] Figure 3 is the plan schematic diagram of tunnel collapse;

[0038] Figure 4 is the longitudinal section schematic diagram of tunnel collapse;

[0039] Figure 5 It is a plan schematic diagram of an open-cut shaft.

[0040] Figure 6 It is a plan schematic diagram of the obstacle clearing for the open-cut shaft and the tunnel.

[0041] Figure 7 It is a longitudinal section schematic diagram of the first construction stage of a specific embodiment.

[0042] Figure 8 It is a plan schematic diagram of the first construction stage of a specific embodiment.

[0043] Figure 9 It is a plane curve element diagram of the newly built subway tunnel in the second construction stage of a specific embodiment.

[0044] Figure 10 It is a longitudinal section schematic diagram of the third construction stage of a specific embodiment.

[0045] Figure 11 It is a longitudinal section schematic diagram of the fourth construction stage of a specific embodiment.

[0046] Figure 12 It is a longitudinal section schematic diagram of the fifth construction stage of a specific embodiment.

[0047] Figure 13 It is a longitudinal section schematic diagram of the sixth construction stage of a specific embodiment.

[0048] In the figure: Open-cut shaft 1, open-cut support structure 1-1, open-cut internal support structure 1-2, obstacle clearing tunnel 2, full casing full rotation obstacle clearing 2-1, newly built shield tunnel 3, right-line new starting shield machine 3-1, starting end of the subway station 4, receiving end of the subway station 5, right-line tunnel 6, right-line shield machine 6-1, right-line collapsed tunnel 6-2, right-line intact tunnel 6-3, right-line tunnel filling 6-4, sealing wall 6-5, left-line tunnel 7, ground vertical drilling 8, curve radius R, transition curve length Ls, tangent length Lt. Detailed implementation manners

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0050] It should be understood that the attached drawings are only for illustrative purposes and should not be construed as a limitation of this patent; for better illustration of this embodiment, some components in the attached drawings may be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the attached drawings may be omitted. The positional relationships described in the attached drawings are only for illustrative purposes and should not be construed as a limitation of this patent.

[0051] The construction method for repairing a shield tunnel of the present invention includes the following steps:

[0052] S1: Emergency treatment of tunnel collapse

[0053] Carry out emergency treatment on the tunnel collapse to control the scope of tunnel collapse and flooding; as Figures 1 - 2 shown in the plan layout drawing for tunnel collapse repair and the longitudinal section layout drawing for tunnel collapse repair, and as Figures 3 - 4 shown in the schematic plan drawing of tunnel collapse and the schematic plan drawing of tunnel collapse.

[0054] Specifically, after the tail seal brush of the shield machine fails and the surrounding soil and water pour into the shield main body and the tunnel, the soil and water outside the tunnel pour into the tunnel. Due to the uneven force on the segment structure of the shield tunnel, the segment structure is extremely prone to collapse. After the tunnel collapses, in order to control the scope of tunnel collapse and flooding, a plain concrete or reinforced concrete plugging wall 6-5 should be built at a set safe distance from the collapse point. The collapsed tunnel is filled with sand, groundwater, and cavities. After the collapse stabilizes, vertical holes 8 are drilled on the ground for grouting to fill the shield tunnel and the shield machine to prevent cavities from remaining.

[0055] S2: Selection of new tunnel route

[0056] Select a new tunnel route to avoid the original collapsed tunnel and fit the horizontal and vertical section lines of the interval tunnel; specifically, the selection of the new tunnel route mainly follows the idea of winding around to avoid the original collapsed tunnel, and at the same time, consider not affecting the construction of another tunnel. Specifically in the design of the horizontal curve, while considering the turning radius of the shield machine equipment, it is necessary to determine the minimum curve radius, the length of the transition curve, and the length of the tangent between curves according to comprehensive factors such as vehicle type, terrain conditions, running speed, and environmental requirements, as long as it meets the requirements for the route in the "Code for Design of Subways". If it is applied to other municipal engineering, highway engineering, and water conservancy projects, it only needs to meet the relevant industry requirements for the route.

[0057] S3: Setting of open-cut shaft

[0058] Set an open-cut shaft 1 in the tunnel collapse area, and use the open-cut method for construction, gradually excavating and gradually erecting the support structure; as Figure 5 shown, the open-cut shaft 1 is provided with an open-cut support structure 1-1 and an open-cut internal support structure 1-2.

[0059] The selection of the open-cut shaft mainly involves the selection of the open-cut scope. Based on the principles of speed and safety and on the basis of making full use of the existing intact tunnel, it needs to be specifically determined in combination with the planar scope (including the plugging wall) of the existing intact shield tunnel, the size selection of the open-cut shaft, etc. The specific technical requirements are as follows:

[0060] a. Selection of the open-cut shaft

[0061] When selecting the open-cut shaft 1, it is necessary to determine it in combination with the planar position of the existing tunnel line and requirements such as in-tunnel backfill plugging.

[0062] Specifically, when selecting the open-cut shaft, a certain position of the complete tunnel can be selected to retain as much of the complete tunnel as possible. If all the existing long-distance intact tunnels are excavated, it is technically feasible, but there are problems such as long construction period and poor economic and technical indicators. Therefore, when a tunnel collapse occurs in the middle of the tunnel, it is necessary to consider adopting the scheme of adding an open-cut shaft in the middle of the tunnel.

[0063] When retaining as much of the complete tunnel as possible, the support structure of the open-cut shaft needs to cut into the complete tunnel, and the following problems need to be solved: 1) When constructing the diaphragm wall trench, it is necessary to consider the measures for temporary plugging in the tunnel. Otherwise, there will be voids on both sides in the tunnel and the diaphragm wall trench cannot be constructed; it can be solved by backfilling plain concrete in the tunnel.

[0064] 2) The connection problem between the open-cut shaft and the existing complete shield tunnel. After the open-cut shaft is completed, there is a gap of about 0.5m - 1.0m between the open-cut shaft and the existing intact tunnel. It is necessary to take measures to connect the open-cut shaft and the intact tunnel;

[0065] When located in a water-rich sand stratum, generally measures such as vertical ground freezing reinforcement or horizontal in-tunnel freezing need to be adopted for connection. When located in other strata, it is necessary to make a comprehensive judgment in combination with the specific stratum and groundwater distribution.

[0066] b. Technical scheme of the open-cut shaft

[0067] Most of the content of the technical scheme of the open-cut shaft is the same as that of the conventional open-cut foundation pit. The main support structures of the open-cut shaft 1 are the diaphragm wall and multiple internal supports.

[0068] In addition, when constructing the trench of the open-cut support structure above the existing tunnel, it is necessary to backfill the existing tunnel with plain concrete or reinforced concrete densely, and the width is generally not less than 3m.

[0069] When constructing the diaphragm wall trench, the geological drilling rig or the full-rotation full-casing drilling rig process can be used to quickly and safely pass through the existing complete shield tunnel.

[0070] After clearing the underground obstacles within the trench construction scope, the diaphragm wall can be completed by using the conventional trench construction equipment.

[0071] For the open-cut shaft to handle the segments within the excavation range, mechanical excavation and manual excavation inside the open-cut shaft are mainly adopted. Meanwhile, the segment bolts are removed inside the tunnel, and finally the segments are hoisted and removed one by one.

[0072] In addition, to reduce the construction risk during the reception of the newly built shield tunnel at the open-cut shaft in the later stage, the diaphragm wall steel bars or structural steel bars within the cutting range of the shield tunnel are replaced with glass fiber bars, and the process of manually breaking through the portal is cancelled.

[0073] S4: Connect the open-cut shaft to the intact shield tunnel

[0074] The technical solution for connecting the open-cut shaft to the intact shield tunnel needs to be judged in combination with the specific strata. When there are problems such as low formation strength and groundwater leakage around the shield tunnel, measures such as ground vertical freezing reinforcement or in-tunnel horizontal freezing can be adopted to freeze and reinforce the soil between the open-cut shaft and the shield tunnel, so as to create a safe working environment for the mined excavation and complete the connection of the open-cut shaft and the intact shield tunnel.

[0075] S5: Clear the underground obstacles

[0076] When selecting the new tunnel route, since the newly built shaft is located within the range of the existing intact tunnel, the open-cut shaft and the newly built shield tunnel will inevitably encounter the original shield tunnel in the later stage. The segment structure of the original shield tunnel will have a direct impact on the construction of the open-cut shaft 1 and the newly built shield tunnel 3. Therefore, it is necessary to clear the underground obstacles in advance.

[0077] Such as Figure 6 As shown, during the obstacle clearing, a full casing full-rotation drilling rig can be used in the obstacle clearing tunnel 2 for full casing full-rotation obstacle clearing 2-1 ground cleaning. After removing the underground obstacles within the casing range, low-strength concrete is backfilled; the casings constructed successively form an overlap within the range of 100 - 150 mm to ensure 100% clearing of the underground obstacles.

[0078] S6: Reception of the newly built shield

[0079] While the open-cut shaft is under construction, a new shield machine is launched at the tunnel reception end and constructed according to the new tunnel route;

[0080] Specifically, while the open-cut shaft is under construction, the right-line new shield machine 3-1 can be launched at the reception end 5 of the originally planned subway station; when the open-cut shaft 1 is constructed, the lower half of the open-cut shaft is backfilled with low-strength concrete; when the newly built shield tunnels into the open-cut shaft, secondary grouting is carried out multiple times on the segment grouting holes to seal the surrounding soil. After the sealing is completed, the local low-strength concrete backfill is excavated and removed, the shield machine is hoisted out, and after casting a circular tunnel section, the entire open-cut shaft is backfilled.

[0081] S7: After the open-cut shaft construction is completed, a new shield machine will be received to complete the repair of the entire shield tunnel.

[0082] The specific implementation process of the present invention is further described below in conjunction with specific embodiments.

[0083] In this embodiment, the subway station starting end 4 and the subway station receiving end 5 serve as the tunnel starting end and the tunnel receiving end of the left-line tunnel 7 and the right-line tunnel 6, respectively. The right-line tunnel 6 collapses, and the right-line complete tunnel 6-3 is behind the collapsed right-line tunnel 6-2, and the right-line shield machine 6-1 is in front of the collapsed right-line tunnel 6-2. The right-line tunnel filling material 6-4 is filled in the collapsed right-line tunnel 6-2.

[0084] Phase 1: Figure 7 and Figure 8 As shown, a blocking wall 6-5 is built in the tunnel, and the tunnel and the shield machine are filled after the scope of tunnel collapse is determined by ground exploration, geophysical scanning and other means to prevent the upper soil from collapsing due to loose filling inside.

[0085] The second stage: Figure 9 As shown, the horizontal and vertical sections of the interval tunnel are fitted to meet the operational requirements.

[0086] The third stage: Figure 10 As shown, a full-casing, full-rotation drilling rig is used on the ground to clear underground obstacles.

[0087] Stage 4: Figure 11 As shown, 1) an open-cut shaft 1 is set near the blocking wall, and the open-cut method is adopted for construction, and the excavation and support structure are gradually set up. 2) While the open-cut shaft 1 is being constructed, the right-line new starting shield machine 3-1 can be started at the originally planned subway station receiving end 5.

[0088] Stage 5: Figure 12 As shown, during the construction of the open-cut shaft 1, the new starting shield machine 3-1 of the right line is constructed according to the adjusted new line; after the construction of the open-cut shaft 1 is completed, the dark excavation connection with the right-line complete tunnel 6-3 is completed, and the blocking wall 6-5 of the right-line tunnel is removed; the lower half of the open-cut shaft 1 is backfilled with plain concrete to create safe receiving conditions for the new starting shield machine 3-1 of the right line.

[0089] Stage 6: Figure 13 As shown, when the newly built shield tunneling reaches the backfilled open-cut shaft 1, multiple secondary grouting is performed on the grouting holes of the segments to seal the soil around the segments. When the sealing is completed, the backfilled concrete backfill body is partially excavated, the shield machine is hoisted out, and after a circular tunnel is cast in place, the entire open-cut shaft is backfilled.

[0090] Phase 7: At this point, the entire shield tunnel repair is completed.

[0091] The above embodiments are merely examples of the technical solutions of the present invention. The present invention is not limited to the contents described in the above embodiments, but is subject to the scope defined by the claims. Any modification, supplement or equivalent replacement made by a person skilled in the art based on the embodiment is within the scope of protection required by the claims of the present invention.

Claims

1. A construction method for repairing a shield tunnel, characterized in that: The following steps are involved: S1: Carry out emergency treatment for tunnel collapse and control the scope of tunnel collapse and flooding; S2: Select a new tunnel route to avoid the original collapsed tunnel and fit the horizontal and vertical section of the interval tunnel; S3: Set up an open-cut shaft in the tunnel collapse area, adopt open-cut construction, excavate gradually, and gradually erect support structures; S4: Connect the open-cut shaft with the intact shield tunnel; S5: Clear underground obstacles; S6: While the open-cut shaft is being constructed, a new shield machine is started at the receiving end of the tunnel to construct along the new tunnel route; S7: After the open-cut shaft construction is completed, a new shield machine will be received to complete the repair of the entire shield tunnel.

2. The construction method for repairing a shield tunnel according to claim 1, characterized in that: In step S1, the emergency treatment of tunnel collapse is specifically as follows: building a plain concrete or reinforced concrete blocking wall at a safe distance set from the collapse point; and vertically drilling holes on the ground and injecting grout to fill the shield tunnel and the shield machine after the collapse is stabilized.

3. The construction method for repairing a shield tunnel according to claim 2, characterized in that: In step S3, the support structure of the open-cut shaft includes an underground continuous wall and multiple internal supports.

4. The construction method for repairing a shield tunnel according to claim 3 is characterized in that: In step S3, when the support structure of the open-cut vertical shaft is trenched above the existing tunnel, the existing tunnel hole is backfilled with plain concrete or reinforced concrete to be dense, with a width of not less than 3m; when the ground-connected wall is trenched, a geological drill or a full-rotation full-casing drill is used to penetrate the existing complete shield tunnel.

5. The construction method for repairing a shield tunnel according to claim 4, characterized in that: In the step S4, the connection between the open-cut shaft and the intact shield tunnel is specifically: freezing and reinforcing the soil between the open-cut shaft and the intact shield tunnel.

6. The construction method for repairing a shield tunnel according to claim 5, characterized in that: In step S4, the freezing reinforcement adopts vertical freezing reinforcement on the ground or horizontal freezing in the cave.

7. The construction method for repairing a shield tunnel according to claim 6, characterized in that: In step S5, when clearing underground obstacles, a full-casing fully rotary drilling rig is used to clean the ground, and the underground obstacles within the casing range are taken out and backfilled with concrete; the casings constructed successively form an overlap within the range of 100 to 150 mm, completing the complete clearing of the underground obstacles.

8. The construction method for repairing a shield tunnel according to any one of claims 1 to 7, characterized in that: In step S6, after the open-cut shaft construction is completed, the lower half of the open-cut shaft is backfilled with plain concrete.

9. The construction method for repairing a shield tunnel according to claim 8, characterized in that: In step S6, after the newly built shield tunneling reaches the inside of the backfilled open-cut shaft, multiple secondary groutings are performed on the grouting holes of the segments to seal the soil around the segments.

10. The construction method for repairing a shield tunnel according to claim 9, characterized in that: In step S6, after the soil around the pipe segment is sealed, the concrete backfill body is partially excavated and the shield machine is hoisted out. After the circular tunnel is cast in place, the entire open-cut shaft is backfilled, and the entire shield tunnel is repaired.

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