Freezing repair method for shield segment in water-rich sand layer

Abstract

The invention belongs to the technical field of shield segment repair, and discloses a freezing repair method for a shield segment in a water-rich sand layer, which comprises the following steps of: constructing a repair well on the outer side of a damaged shield segment close to a shield tunnel; freezing holes are constructed in the repair well, then freezing pipes are connected for freezing construction, and a freezing curtain corresponding to the damaged shield segment is formed; after the frozen curtain reaches the design strength, the frozen state is kept, and frozen soil around the damaged segment is manually chiseled away; the positioned damaged shield segment is repaired, and it is determined that the repairing effect reaches the expected state; and removing the freezing pipe to release the freezing state, and then backfilling and repairing the well to the ground elevation. According to the method, under the condition that normal use of an existing tunnel is not affected, the damaged shield segment can be rapidly and effectively repaired, the construction risk of constructors is reduced, economic losses can be rapidly, safely, scientifically and reasonably reduced, a new repairing method is provided for the field of underground tunnel engineering, and the method is suitable for application and popularization.

Description

Technical Field

[0001] The present invention relates to the technical field of shield segment repair, and particularly to a freezing repair method for shield segments in a water-rich sand layer. Background Art

[0002] The shield method is the main method for tunnel excavation nowadays. Shield tunnel segments are precast concrete components installed on the inner wall of the tunnel during the tunneling process of the shield machine. They are the innermost barrier of the tunnel, bearing the functions of resisting soil pressure, groundwater pressure, and some special loads, and affecting the waterproof performance and durability of the tunnel. When the shield tunnel is located in a water-rich sand layer, the sand layer has low stability and is extremely prone to water and sand seepage of the installed segments of the shield tunnel under the action of groundwater.

[0003] The existing repair of shield tunnel segments generally adopts methods such as grouting reinforcement, internal repair, or shaft repair; however, it is difficult to fundamentally solve the problem of water and sand seepage by using ordinary grouting reinforcement measures; and for segment repair or replacement construction, it is necessary to chisel the damaged position of the segment. When chiseling and repairing from the inside of the tunnel, traffic needs to be blocked for support and repair, with a long construction time and great construction difficulty, seriously affecting the normal use of the tunnel; when repairing from the outside of the tunnel by constructing a repair shaft, it is easy to cause water and sand gushing when chiseling the damaged segment in a water-rich sand layer, and it is difficult to ensure the safety of construction personnel. Therefore, how to thoroughly repair or replace the shield tunnel segments in a water-rich sand-bearing stratum while ensuring project safety and the safety of construction personnel has important practical significance.

[0004] Therefore, the present invention discloses a freezing repair method for shield segments in a water-rich sand layer to solve the above technical problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a freezing repair method for shield segments in a water-rich sand layer to solve the problems existing in the prior art.

[0006] To achieve the above purpose, the present invention provides the following solution: The present invention provides a freezing repair method for shield segments in a water-rich sand layer, including the following steps:

[0007] Locate the damaged shield segments on the existing tunnel, and construct a repair shaft on the outside of the damaged shield segments adjacent to the shield tunnel;

[0008] Construct freezing holes from the inside of the repair shaft, and then connect the freezing pipes for freezing construction to form a freezing curtain corresponding to the damaged shield segments;

[0009] After the freezing curtain reaches the design strength, maintain the freezing state, and manually chisel the frozen soil around the damaged segments;

[0010] Repair the damaged shield segments that have been located and ensure that the repair effect has reached the expected state;

[0011] Remove the frozen pipe to release the frozen state, and then backfill the repair well to the ground level.

[0012] Preferably, in the step of constructing a repair well, a repair well enclosure structure is first constructed at the located repair well position for enclosure to facilitate subsequent repair well excavation construction, and then a dewatering well is constructed to reduce the impact of groundwater.

[0013] Preferably, a water-stop curtain is provided on the outer side of the underground area of the repair well enclosure structure.

[0014] Preferably, a base full-floor reinforcement is constructed at the bottom of the repair well, a repair well lining structure is constructed above the base full-floor reinforcement, and the repair well lining structure is distributed on the inner wall of the repair well.

[0015] Preferably, a plurality of repair well support structures are arranged in the repair well, and the plurality of repair well support structures are longitudinally distributed in the repair well.

[0016] Preferably, in the step of constructing the freezing holes, it is also necessary to simultaneously construct a number of temperature measuring holes and pressure relief holes arranged at intervals. The temperature measuring holes are used to measure the temperature of the frozen soil, and the pressure relief holes are used to release the pressure generated during the freezing process.

[0017] Preferably, in the step of manually chiseling away the frozen soil, the freezing pipes around the frozen soil are retained and maintained in a frozen state, and then the freezing pipes in the middle corresponding to the damaged shield segment are removed, and then the soil is manually removed to form a maintenance channel that is convenient for repairing the damaged shield segment.

[0018] Preferably, a working platform is provided at the bottom end of the maintenance passage for facilitating construction, and a supporting structure for reinforcement is provided in the maintenance passage.

[0019] Preferably, in the process of repairing the damaged shield segments, if the damage to the damaged shield segments is not serious, the damaged shield segments are sealed or grouting is performed; if the damage to the damaged shield segments is serious, the damaged shield segments are replaced as a whole.

[0020] Preferably, in the steps of removing the frozen pipe to thaw the freezing state and then backfilling the repair well to the ground elevation, the frozen hole after removing the frozen pipe is backfilled with prefabricated cement mortar, and after the prefabricated cement mortar reaches a set strength, the backfill material is used to backfill the repair well and maintenance channel.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects: The present invention discloses a freezing repair method for shield segments in a water-rich sand layer. First, the damaged segments are located and a repair well is constructed outside them to provide an operating space for subsequent repair work. By constructing the repair well from the outside of the tunnel, the influence on the normal use of the tunnel during internal repair is avoided, ensuring the continuous traffic capacity of the existing tunnel and reducing the interference to traffic or other tunnel use functions. Then, freezing holes are constructed from within the repair well and freezing pipes are connected for freezing construction to form a freezing curtain, effectively suppressing the fluidity of the soil in the water-rich sand layer, enhancing the self-stability of the soil, greatly reducing the risk of water and sand gushing during construction, ensuring the safety of construction personnel, and reducing potential safety hazards during the construction process. When the freezing curtain reaches the designed strength, the frozen soil around the damaged segments is removed to create conditions for repairing the segments, providing a construction space for repairing the damaged shield segments. By removing the frozen soil around the damaged segments to form a working platform, it is convenient to comprehensively inspect and repair the damaged segments, reducing the construction difficulty. Then, the damaged segments are repaired and the effect is confirmed. Whether it is by plugging, grouting treatment, or replacing the whole piece, it can effectively repair the damaged segments according to the degree of damage, solve the problems of water and sand seepage, and improve the waterproof performance and structural stability of the tunnel. Finally, the freezing pipes are removed and the repair well is backfilled to restore the ground condition. The freezing pipes are removed and the repair well is backfilled to the ground elevation, restoring the construction site to the state before construction, reducing the long-term impact on the surrounding environment, avoiding the restriction of the repair well on the surrounding land use, and ensuring the subsequent normal use of the site.

[0022] The present invention can quickly and effectively repair damaged shield segments without affecting the normal use of the existing tunnel, reduce the construction risk of construction personnel, quickly, safely, scientifically, and reasonably reduce economic losses, provide a new repair method for the field of underground tunnel engineering, and is suitable for popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0024] Figure 1 is a flow chart of the freezing repair method for shield segments in the water-rich sand layer of the present invention;

[0025] Figure 2 is a top view of the repair well of the present invention;

[0026] Figure 3 is of the present invention Figure 2 a schematic cross-sectional view taken along line A-A in;

[0027] Figure 4 is a schematic diagram of the arrangement of freezing pipes of the present invention;

[0028] Figure 5 This is a schematic diagram of a damaged shield working platform of the present invention;

[0029] Figure 6 This is a schematic diagram of the backfill state of the repair well of the present invention;

[0030] In the figure: 1. Existing tunnel; 2. Repair well; 3. Dewatering well; 4. Repair well enclosure structure; 5. Damaged shield segments; 6. Repair well support structure; 7. Repair well lining structure; 8. Base full-floor reinforcement; 9. Water-stop curtain; 10. Frozen pipe; 11. Frozen reinforcement; 12. Working platform; 13. Soil removal; 14. Support structure; 15. Repaired shield segments; 16. Backfill material. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Reference Figures 1-6 As shown, this embodiment provides a method for repairing frozen shield segments in water-rich sand layers, comprising the following steps:

[0034] Locate the damaged shield segment 5 on the existing tunnel 1, and construct a repair well 2 on the outer side of the damaged shield segment 5 adjacent to the shield tunnel;

[0035] A freezing hole is constructed in the repair well 2, and then a freezing pipe 10 is connected to perform freezing construction to form a freezing curtain corresponding to the damaged shield segment 5;

[0036] When the freezing curtain reaches the designed strength, keep it frozen and manually remove the frozen soil around the damaged segment;

[0037] Repair the damaged shield segment 5 located, and ensure that the repair effect reaches the expected state;

[0038] The frozen pipe 10 is removed to release the frozen state, and then the repair well 2 is backfilled to the ground level.

[0039] The present invention discloses a freezing repair method for shield segments in a water-rich sand layer. First, the damaged segments are located and a repair well 2 is constructed outside them to provide an operating space for subsequent repair work. By constructing the repair well 2 from outside the tunnel, the normal use of the tunnel during internal repair is avoided, ensuring the continuous traffic capacity of the existing tunnel 1 and reducing interference with traffic or other tunnel use functions. Then, freezing holes are constructed from within the repair well 2 and freezing pipes 10 are connected for freezing construction to form a freezing curtain, effectively suppressing the fluidity of the soil in the water-rich sand layer, enhancing the self-stability of the soil, greatly reducing the risk of water and sand gushing during construction, ensuring the safety of construction personnel, and reducing potential safety hazards during construction. When the freezing curtain reaches the design strength, the frozen soil around the damaged segments is chiseled away to create conditions for repairing the segments, providing a construction space for repairing the damaged shield segments 5. By chiseling away the frozen soil around the damaged segments to form a working platform 12, it is convenient to comprehensively inspect and repair the damaged segments, reducing the construction difficulty. Then, the damaged segments are repaired and the effect is confirmed. Whether it is by plugging, grouting treatment, or replacing the whole segment, the damage degree of the segments can be effectively repaired, solving the problems of water and sand seepage and improving the waterproof performance and structural stability of the tunnel. Finally, the freezing pipes 10 are removed and the repair well 2 is backfilled to restore the ground condition. Removing the freezing pipes 10 and backfilling the repair well 2 to the ground elevation restores the construction site to its pre-construction state, reducing the long-term impact on the surrounding environment, avoiding restrictions on the use of the surrounding land by the repair well 2, and ensuring the subsequent normal use of the site. The present invention can quickly and effectively repair the damaged shield segments 5 without affecting the normal use of the existing tunnel 1, reducing the construction risk for construction personnel, quickly, safely, scientifically, and reasonably reducing economic losses, and providing a new repair method for the field of underground tunnel engineering, which is suitable for popularization and use.

[0040] In a further optimized solution, in the step of constructing the repair well 2, first, a repair well enclosure structure 4 is constructed at the located position of the repair well 2 for enclosure, facilitating the subsequent excavation construction of the repair well 2. Then, a dewatering well 3 is constructed to reduce the influence of groundwater. Since the construction is carried out in a water-rich sand layer, when constructing the repair well 2, the dewatering well 3 is first constructed at the located position to reduce the influence of groundwater, effectively lowering the groundwater level and reducing the interference of groundwater on the construction of the repair well 2, such as avoiding the problem of water gushing during construction. Then, the repair well enclosure structure 4 is constructed outside the selected position for enclosure, providing a safety enclosure for the subsequent excavation construction of the repair well 2, ensuring the stability of the surrounding soil during construction and preventing collapse accidents.

[0041] For the further optimized solution, a water-stop curtain 9 is provided on the outer side of the repair well retaining structure 4 located in the underground area. By setting the water-stop curtain 9 on the outer side of the repair well retaining structure 4 located in the underground area, the infiltration of groundwater into the construction area of the repair well 2 is further prevented, the waterproof effect is enhanced, and in coordination with the dewatering well 3 and the retaining structure, the construction of the repair well 2 is ensured to be carried out in a dry and stable environment.

[0042] For the further optimized solution, a full-bottom foundation reinforcement 8 is constructed at the bottom end of the repair well 2, and a repair well lining structure 7 is constructed above the full-bottom foundation reinforcement 8. The repair well lining structure 7 is distributed on the inner wall of the repair well 2. Constructing a full-bottom foundation reinforcement at the bottom end of the repair well 2 enhances the bearing capacity of the foundation at the bottom of the repair well 2 and prevents the repair well 2 from settling during construction and use; above the full-bottom foundation reinforcement and on the side wall of the repair well 2, the repair well lining structure 7 is constructed. The lining structure is distributed on the inner wall of the repair well 2, which plays a role in protecting and strengthening the inner wall of the repair well 2 and improves the overall stability of the repair well 2.

[0043] For the further optimized solution, a number of repair well support structures 6 are provided in the repair well 2, and the number of repair well support structures 6 is longitudinally distributed in the repair well 2. By setting a number of longitudinally distributed repair well support structures 6 in the repair well 2, the well wall of the repair well 2 can be effectively supported, preventing the well wall from deforming or collapsing due to soil pressure during construction, and further ensuring construction safety.

[0044] In summary, the construction process of the repair well 2 is as follows:

[0045] On the tunnel side close to the damaged segment and on the outer side adjacent to the tunnel retaining structure, the construction of the repair well retaining structure 4 is carried out. The construction scope of the repair well retaining structure 4 should be larger than the scope of the damaged segment; ensure that the damaged segment can be smoothly transported out of the repair well 2;

[0046] The water-stop curtain 9 is constructed on the outer side of the repair well retaining structure 4 to ensure that groundwater will not have an adverse impact on the construction scope. At the same time, at the inner side base of the repair well retaining structure 4, the full-bottom foundation reinforcement 8 is constructed to ensure the stability and bearing capacity of the foundation; the full-bottom foundation reinforcement of the repair well 2 adopts full-bottom MJS reinforcement; the water-stop curtain 9 of the repair well 2 adopts wall joint MJS water-stop curtain 9;

[0047] A number of dewatering wells 3 are constructed around the repair well 2 to lower the water level in the foundation pit of the repair well 2;

[0048] The excavation of the foundation pit of the repair well 2 starts from the excavation of the surface soil while constructing the first repair well support structure 6, and the repair well support structure 6 is constructed successively while excavating the soil from the surface to the lower layer; after excavating to the base, manual bottom cleaning is carried out, and the excavator is used in cooperation with manual labor to level the base, and the foundation trench is inspected and accepted; after the foundation trench is inspected and accepted, the concrete cushion is poured in time, and the concrete cushion jointly constitutes the repair well lining structure 7.

[0049] For a further optimized solution, during the step of constructing freezing holes for construction, a number of temperature measurement holes and pressure relief holes arranged at intervals need to be constructed synchronously. The temperature measurement holes are used to measure the temperature of the frozen soil mass, and the pressure relief holes are used to release the pressure generated during the freezing process. When constructing the freezing holes for construction, the temperature measurement holes and pressure relief holes arranged at intervals are constructed synchronously. The temperature measurement holes can monitor the temperature of the frozen soil mass in real time, providing a basis for judging the freezing effect and ensuring that the frozen curtain reaches the designed strength; the pressure relief holes can release the pressure generated during the freezing process in a timely manner, avoiding damage to the soil mass or the freezing pipes 10 caused by excessive pressure.

[0050] In summary, the process of freezing construction is specifically as follows:

[0051] Design the thickness and shape of the frozen curtain based on the position and size of the damaged segment. The freezing range should be reasonably selected to ensure the smooth progress of subsequent construction;

[0052] To control soil and water loss in the stratum, an orifice sealing device must be adopted to prevent adverse situations such as water inrush and quicksand during drilling, and grouting should be carried out in a timely manner after the hole is formed to control stratum settlement; when constructing the freezing holes for construction, temperature measurement holes, pressure relief holes and temperature control holes should be arranged simultaneously. The construction methods of the temperature measurement holes, pressure relief holes and temperature control holes are the same as those of the freezing holes for construction;

[0053] Arrange the freezing pipes 10. The freezing pipes 10 should be pre-piped before being lowered into the freezing holes to ensure the concentricity of the freezing pipes 10; after arranging the freezing pipes 10, the gap between the freezing pipes 10 and the hole mouth pipes should be sealed with leak-proof materials;

[0054] While drilling the holes for construction, a freezing station is set up and installed on the ground synchronously. After the drilling construction is completed, it can be transferred to the freezing device installation stage, and then the soil mass is strengthened and frozen for operation; the freezing liquid is connected to the freezing pipes 10 through pipelines from the freezing station and via the repair well 2 to form a frozen reinforcement body 11.

[0055] During the freezing period, a concrete partition wall and a safety protection wall are constructed in the repair well 2, and a safety door is installed on the protection wall.

[0056] For a further optimized solution, during the step of manually chiseling the frozen soil mass, the freezing pipes 10 around the frozen soil mass are retained and maintained in the frozen state, and then the freezing pipes 10 corresponding to the damaged shield segments 5 in the middle are removed, and then the chiseled soil mass 13 is manually removed to form a maintenance passage for facilitating the repair of the damaged shield segments 5. When manually chiseling the frozen soil mass, retaining the freezing pipes 10 around and maintaining the frozen state can stabilize the surrounding soil mass, maintain the freezing strength and prevent water inrush and quicksand; removing the freezing pipes 10 corresponding to the damaged shield segments 5 in the middle and then manually removing the chiseled soil mass 13 to form a maintenance passage facilitates the repair operation of the damaged segments.

[0057] For a further optimized solution, a working platform 12 for facilitating construction is provided at the bottom end of the maintenance passage, and a support structure 14 for reinforcement is arranged in the maintenance passage. The working platform 12 is provided at the bottom end of the maintenance passage, providing a stable operating space for construction workers and facilitating the repair work; the support structure 14 is arranged in the passage to reinforce the maintenance passage, prevent the passage from collapsing during the repair process, and ensure the safety of construction workers.

[0058] In summary, the process of manually chiseling the frozen soil mass is as follows:

[0059] When the thickness detection of the frozen wall meets the design requirements, the next step of construction can be carried out. It is confirmed that the strength of the frozen curtain is achieved through the pre-arranged temperature measurement holes. At the same time, the pressure relief hole detection should be carried out before construction to confirm the rising value of the water pressure in the pressure relief hole;

[0060] Maintain the frozen state, chisel the soil mass around the damaged shield segment 5. According to the size of the damaged shield segment 5, reasonably select the range of the chiseled frozen reinforcement 11 to leave a construction space for repairing or replacing the damaged shield segment 5. The damaged shield segment 5 should be clearly exposed in the maintenance passage formed by chiseling the frozen soil to facilitate the next step of construction; because the soil mass is in a frozen state during the chiseling construction, the fluidity of the water-rich sand layer soil mass can be inhibited, the self-stability of the soil mass can be stabilized, and accidents such as quicksand, piping, and even collapse of the water-rich sand layer soil mass can be avoided;

[0061] The working platform 12 in the maintenance passage is laid on the ground and is a construction platform pre-erected during the freezing period, providing a working surface for manually chiseling the frozen reinforced soil mass and facilitating construction; at the same time, a support structure 14 for preventing the thaw settlement of the frozen soil mass is arranged in the maintenance passage; at the same time, when chiseling the soil mass around the damaged shield segment 5, it is excavated in sequence from the repair well enclosure structure 4 to the damaged shield segment 5; when chiseling the soil mass around the damaged shield segment 5, it is excavated from the outside of the tunnel to the shield segment and from top to bottom in sequence; when a freezing pipe 10 is encountered during the excavation process, it is protected, and the exposed freezing pipe 10 is thermally insulated;

[0062] The chiseled frozen soil mass is transported out of the repair well 2 to the ground surface to avoid affecting the construction.

[0063] For a further optimized solution, during the process of repairing the damaged shield segment 5, when the damage of the damaged shield segment 5 is not serious, plugging or grouting treatment is carried out on the damaged shield segment 5; when the damage of the damaged shield segment 5 is serious, the damaged shield segment 5 is replaced as a whole. According to the damage degree of the damaged shield segment 5, different repair methods are adopted, which can repair the segment more reasonably and efficiently, ensure the repair effect, thoroughly solve problems such as water seepage and sand leakage, and also reduce the maintenance cost. Specifically, when the damage is not serious, plugging or grouting is carried out, and when the damage is serious, replacing as a whole can thoroughly solve the problems of water seepage and sand leakage. As for whether replacement is needed, it can be determined according to the tunnel shield tunnel environment and usage status. For details, please refer to the appendix Figure 515 of the repaired shield segments.

[0064] In one embodiment of the present invention, repair or replacement construction is carried out based on a working platform 12 formed by chiseling out the frozen reinforced soil; the working platform 12 is formed by pouring concrete after chiseling out the frozen reinforced body 11; and the repair materials or replacement shield segments are transported from the repair well 2.

[0065] To further optimize the solution, in the step of removing the freezing pipe 10 to release the freezing state and then backfilling the repair well 2 to the ground elevation, the freezing hole after removing the freezing pipe 10 is backfilled with prefabricated cement mortar, and after the prefabricated cement mortar reaches a set strength, the backfill material 16 is used to backfill the repair well 2 and the maintenance channel. After removing the freezing pipe 10, backfilling the freezing hole with prefabricated cement mortar can prevent stratum cavitation and ensure soil stability; after it reaches a set strength, the backfill material 16 is used to backfill the repair well 2 and the maintenance channel; soil deformation caused by premature backfilling is avoided, and the stability of the structure after repair is ensured.

[0066] In summary, the process of backfilling the repair well 2 to the ground elevation is as follows:

[0067] After the damaged shield segment 5 is repaired, the frozen pipes 10 are removed in layers and groups, from top to bottom, by artificial partial thawing. Hot brine is circulated in the freezer to melt the frozen soil around the frozen pipes 10 to 30-50 mm. Two jacks are set on the trough wall to push the frozen pipes 10 outward horizontally. It is better to remove the frozen pipes 10 within the range of the working platform 12, and other frozen pipes 10 abandoned in the stratum should be filled.

[0068] After the frozen pipe 10 is removed, the safety door is removed as compactly as possible to reduce the exposure time of the excavation surface;

[0069] The backfill construction of the repair well 2 is carried out in batches. First, the working platform 12 and the supporting structure 14 used for repairing the pipe segments should be removed, and then the supporting structure in the repair well 2 should be removed simultaneously during the backfilling of subsequent batches. The backfilling of the repair well 2 should be carried out quickly to avoid the risk of water and sand gushing due to thawing of the frozen reinforced soil after the freezing pipe 10 is pulled out. The materials for backfilling the repair well 2 should be selected reasonably to ensure the overall stability of the tunnel structure.

[0070] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0071] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A freezing repair method for shield segments in a water-rich sand layer, characterized in that The following steps are involved: Locating a damaged shield segment (5) on an existing tunnel (1), and constructing a repair well (2) outside the damaged shield segment (5) adjacent to the shield tunnel; A freezing hole is constructed in the repair well (2), and then a freezing pipe (10) is connected to perform freezing construction to form a freezing curtain corresponding to the damaged shield segment (5); When the freezing curtain reaches the designed strength, keep it frozen and manually remove the frozen soil around the damaged segment; Repairing the located damaged shield segment (5) and ensuring that the repair effect reaches the expected state; The frozen pipe (10) is removed to release the frozen state, and then the repair well (2) is backfilled to the ground level.

2. The freezing repair method for shield segments in water-rich sand strata according to claim 1, characterized in that: In the step of constructing the repair well (2), a repair well enclosure structure (4) is first constructed at the located repair well (2) to provide enclosure to facilitate subsequent excavation and construction of the repair well (2), and then a dewatering well (3) is constructed to reduce the impact of groundwater.

3. The freezing repair method for shield segments in water-rich sand layers according to claim 2, characterized in that: The repair well enclosure structure (4) is provided with a water-stop curtain (9) outside the underground area.

4. The freezing repair method for shield segments in water-rich sand layers according to claim 2, characterized in that: A base full-chamber reinforcement body (8) is constructed at the bottom end of the repair well (2), a repair well lining structure (7) is constructed above the base full-chamber reinforcement body (8), and the repair well lining structure (7) is distributed on the inner wall of the repair well (2).

5. The freezing repair method for shield segments in water-rich sandy strata according to claim 4, characterized in that: A plurality of repair well support structures (6) are arranged in the repair well (2), and the plurality of repair well support structures (6) are longitudinally distributed in the repair well (2).

6. The freezing repair method for shield segments in water-rich sand strata according to claim 1, wherein: In the step of constructing the freezing holes, it is also necessary to simultaneously construct a number of temperature measuring holes and pressure relief holes set at intervals. The temperature measuring holes are used to measure the temperature of the frozen soil, and the pressure relief holes are used to release the pressure generated during the freezing process.

7. The freezing repair method of the shield segment in the water-rich sand layer according to claim 1, characterized in that: In the step of manually chiseling away the frozen soil, the freezing pipes (10) around the frozen soil are retained and maintained in a frozen state, and then the freezing pipes (10) in the middle corresponding to the damaged shield segment (5) are removed, and then the chiseled soil (13) is manually removed to form a maintenance channel that is convenient for repairing the damaged shield segment (5).

8. The freezing repair method of the shield segment in the water-rich sand layer according to claim 7, characterized in that: A working platform (12) is arranged at the bottom end of the maintenance passage for facilitating construction, and a supporting structure (14) is arranged in the maintenance passage for reinforcement.

9. The freezing repair method for shield segments in water-rich sand strata according to claim 1, characterized in that: In the process of repairing the damaged shield segment (5), if the damaged shield segment (5) is not seriously damaged, the damaged shield segment (5) is sealed or grouting is performed; if the damaged shield segment (5) is seriously damaged, the damaged shield segment (5) is replaced as a whole.

10. The freezing repair method of the shield segment in the water-rich sand layer according to claim 1, characterized in that: In the step of removing the freezing pipe (10) to release the freezing state and then backfilling the repair well (2) to the ground level, the freezing hole after removing the freezing pipe (10) is backfilled with prefabricated cement mortar, and after the prefabricated cement mortar reaches a set strength, the backfill material (16) is used to backfill the repair well (2) and the maintenance channel.

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