Disease treatment method suitable for differential settlement of operation immersed tube tunnel foundation

Abstract

The invention relates to the technical field of immersed tunnels, and discloses a differential settlement disease treatment method suitable for an operation immersed tunnel foundation, which comprises the following steps: S1, early-stage preparation work; s2, evaluating an existing immersed tube tunnel disease and a treatment method; s3, the position of a drilled hole in the disease position of the existing immersed tunnel is determined; s4, single-hole grouting pressure is determined through a grouting pressure calculation formula; s5, the number and spacing of directional grouting holes are determined; s6, determining the grouting sequence of the directional grouting holes; s7, directional grouting is conducted, so that the tunnel bottom plate is lifted; and S8, after directional grouting is conducted on the immersed tube tunnel to enable the tunnel bottom plate to be lifted to the designed elevation, part of the immersed tube tunnel is still disengaged. The tunnel foundation is lifted to the designed elevation through directional grouting of the damaged pipe joint, the problem of differential settlement of the tunnel is fundamentally solved, local disengaging of the tunnel bottom plate foundation still exists after directional grouting, local disengaging is solved through bottom plate trepanning grouting, tunnel structure deformation is reduced, and the bearing capacity of the tunnel foundation is improved.

Description

Technical Field

[0001] This invention relates to the field of immersed tunnel technology, specifically to a method for treating uneven settlement defects in the foundation of an operational immersed tunnel. Background Technology

[0002] The immersed tunnel industry has made rapid progress, and it is now among the world's leaders in terms of both the number of tunnels and the technology of tunnel construction.

[0003] Over time, immersed tunnels encounter various problems during use, such as foundation detachment and uneven settlement, due to adverse geological conditions, unfavorable loads, and excessive siltation. Therefore, there are relatively few domestic case studies available on how to repair the foundations of immersed tunnels in cases of foundation detachment and uneven settlement, and related theoretical and technical research is still relatively lagging.

[0004] Traditional repair processes often employ a blind grouting strategy. This method lacks specificity, and the selection of grouting pressure and materials is unscientific. The underlying structural condition is unclear, resources are wasted arbitrarily, and the repair may ultimately only address the symptoms, not the root cause. Such repair methods not only consume significant human and material resources but also increase the risks associated with later maintenance.

[0005] The lack of a rigorous and systematic approach is another major shortcoming of current technology during construction. Many existing technologies lack scientific grouting sequences and parameter selection, resulting in poor filling effects. Especially during secondary grouting, the inability to dynamically monitor and adjust leads to compromised construction safety and efficiency. Consequently, projects often fail to achieve the desired results, increasing safety hazards and subsequent economic costs. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for treating uneven settlement of foundations in operational immersed tunnels. This method solves the problems of existing technologies, which struggle to achieve safe, controllable, and precise lifting and repositioning when dealing with uneven settlement in operational immersed tunnels, and which are prone to leaving behind the risk of foundation voids.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for treating uneven settlement defects in the foundation of an operational immersed tunnel, comprising the following steps:

[0008] S1. Preliminary preparations, including:

[0009] Geological data survey and data collection on existing immersed tunnels;

[0010] Existing hydrological and meteorological monitoring data for the basin where the immersed tunnel is located;

[0011] Monitoring yielded data on uneven settlement of the tunnel;

[0012] Distribution of backfill thickness at the top of the tunnel section in the defective area;

[0013] S2. Assess existing immersed tunnel defects and determine treatment methods;

[0014] S3. Determine the location of boreholes for defects in existing immersed tunnels;

[0015] S4. Determine the grouting pressure for a single hole using the grouting pressure calculation formula;

[0016] S5. Determine the number and spacing of directional drilling and directional grouting holes;

[0017] S6. Clarify the sequence of directional drilling and grouting of directional grouting holes;

[0018] S7. Directional grouting raises the tunnel floor to the design elevation;

[0019] S8. After the immersed tunnel floor is raised to the design elevation by directional grouting, there are still some voids. Grouting is performed on the voided parts of the tunnel floor.

[0020] Preferably, the geological data collection in step S1 mainly includes conducting a survey of the geological conditions within the immersed tunnel area to determine the soil layers and hydrogeological conditions of the construction area; collecting preliminary design and construction drawings of the immersed tunnel, construction data, and clarifying the structural type of the immersed tunnel, foundation depth data, and the thickness of backfilling at the top of the damaged pipe sections.

[0021] Preferably, the quality assessment of the immersed tunnel in step S2 mainly involves a professional quality inspection unit assessing the current quality of the immersed tunnel, checking specific data on foundation settlement, and assessing and identifying the methods for treating foundation defects.

[0022] Preferably, in step S3, the location of the horizontal directional drilling hole is determined by on-site scanning and analysis of the foundation defects of the immersed tunnel;

[0023] Before implementing the plan, the scope of the defects was first detected and analyzed. Then, a hole was drilled at a distance of h1 = 800 mm from the bottom of the tunnel floor to determine the location of the horizontal directional drilling hole.

[0024] 5. A method for treating uneven settlement defects in the foundation of an operational immersed tunnel according to claim 1, characterized in that, in step S4, the distribution of the backfill thickness at the top of the tunnel section at the defect location is analyzed by on-site testing, and the backfill thickness is set to h3>1m, and the dredging thickness is h=1m; and the grouting pressure is obtained.

[0025] The formula for calculating grouting pressure is:

[0026] P = W - R + f;

[0027] The pressure in a single orifice is:

[0028]

[0029] In the formula, P represents the grouting pressure, W represents the weight of the submerged tube, R represents the buoyancy, f represents the weight of the silt, n represents the number of grouting holes, and ρ represents the grouting pressure of a single grouting hole.

[0030] Preferably, the determination of the number and spacing of directional grouting holes in step S5 specifically includes the following steps;

[0031] When the diffusion radius of the grout cannot be determined, the directional grouting hole layout is initially considered based on a diffusion radius of 1.25m. Multi-segment division and segmented grouting are adopted, with each pipe section being 15m long and having two rows of directional grouting holes. Each work platform is responsible for 10 grouting holes, and the spacing between grouting pipes is arranged according to H3 = 1.5m. If the diffusion radius of the grout is insufficient during the actual grouting process, the directional grouting holes are densified for supplementary grouting.

[0032] Preferably, in step S6, the directional grouting adopts the method of grouting the outer side first and then the inner side, and the inner side grouting adopts the method of grouting the wall edge first and then the middle.

[0033] The grouting sequence of the directional grouting holes is from the outside to the inside. The grouting of the outer side adopts the whole grouting method to reinforce the soil of the sinking pipe foundation.

[0034] For internal grouting, the grouting method is to first construct the holes on both sides of the wall and then construct the hole in the center line. The grouting pressure or grouting range of the directional grouting holes on both sides should not be too large. After the holes on both sides are constructed and provide bearing capacity, the grouting pressure can be increased when constructing the directional grouting hole in the center.

[0035] Preferably, in step S7, the directional drilling grouting strictly controls the grouting pressure of a single hole and the amount of uplift of the tunnel floor.

[0036] One-time grouting is adopted, and the grouting pressure of the working platform (3) is controlled within the calculated ρ grouting pressure. During grouting, the pressure is gradually increased from small to large.

[0037] Grouting should be stopped when the amount of elevation of the tunnel floor reaches ±5mm of the design elevation.

[0038] If the design elevation is not reached within ±5mm, continue grouting until the design requirements are met.

[0039] Preferably, in step S8, after directional grouting, there are still local voids in the tunnel floor slab of the immersed tunnel, and it is necessary to open holes in the tunnel floor slab of the local void area for grouting; during grouting, it is still necessary to divide the local void area of ​​the pipe section into multiple segments and grout in segments.

[0040] Preferably, in step S8, three rows of grouting holes are set in the local void area of ​​the tunnel floor slab, one row on each side wall and one row on the center line. The spacing between the grouting holes in each row is arranged at H=2.5m. The grouting holes at the edge of the side wall are H5=50cm away from the water ditch and cable trough. If the grout diffusion radius is insufficient during the actual grouting process, the grouting holes are densified for supplementary grouting.

[0041] This invention provides a method for treating uneven settlement defects in the foundation of an operational immersed tunnel.

[0042] It has the following beneficial effects:

[0043] 1. This invention raises the tunnel foundation to the design elevation by directional grouting of the damaged pipe sections, fundamentally solving the problem of uneven settlement of the tunnel. After directional grouting, there are still local voids in the tunnel bottom slab foundation. Grouting through openings in the bottom slab solves these local voids, reduces tunnel structural deformation, and improves the bearing capacity of the tunnel foundation.

[0044] 2. This invention employs a refined grouting sequence from the outside in, starting with the edges and then moving to the center, combined with real-time monitoring of the lifting volume. This closed-loop control scheme makes the lifting process of large pipe sections precise and safe. It changes the traditional extensive grouting method that relies on construction experience, solving the problems of blind processes that easily lead to over-lifting or uneven lifting, thus causing secondary damage to the structure.

[0045] 3. This invention utilizes a complete technical system encompassing preliminary surveying, mechanical calculations, process monitoring, and precise construction to achieve controllable and precise lifting and repositioning of immersed tunnels. Compared to existing technologies that rely heavily on experience-based estimations and extensive construction methods, this invention solves the problems of difficulty in quantifying the lifting amount and the uncontrollability of the process. Attached Figure Description

[0046] Figure 1 This is a three-dimensional schematic diagram of the grouting process of the present invention;

[0047] Figure 2 This is a schematic diagram of the directional grouting plan of the present invention;

[0048] Figure 3 This is a cross-sectional view of the directional grouting of the present invention;

[0049] Figure 4 This is a schematic diagram of the grouting plan of the base plate of the present invention;

[0050] Figure 5 This is a schematic diagram of the grouting section at the bottom of the pipe according to the present invention.

[0051] The components include: 1. Immersed tunnel; 2. Directional grouting hole; 3. Working platform; 4. Grouting pipe; 5. Bottom slab grouting hole; 6. Tunnel bottom slab; 7. Directional drilling; 8. Cable trench; 9. Local void area; 10. Silt backfill thickness; 11. Dredging thickness; 12. Immersed tunnel foundation. Detailed Implementation

[0052] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] Please see the appendix Figure 1 -Attached Figure 5 This invention provides a method for treating uneven settlement defects in the foundation of an operational immersed tunnel, comprising the following steps:

[0054] S1. Preliminary preparations, including:

[0055] Geological data survey and data collection of existing immersed tunnel 1;

[0056] Existing hydrological and meteorological monitoring data for the basin where immersed tunnel 1 is located;

[0057] Monitoring yielded data on uneven settlement.

[0058] The distribution of siltation thickness of 10 mm at the defective section of the immersed tube foundation was inspected.

[0059] Specifically, the purpose of step S1 in this embodiment is to provide comprehensive and accurate initial parameters for subsequent disease assessment, scheme decision-making, mechanical calculation and construction control through systematic data collection and surveying.

[0060] As a specific implementation of step S1, it is first necessary to conduct geological data surveys and collect engineering data on the existing immersed tunnel 1. For example, this process includes conducting a detailed survey of the geological conditions within the influence range of the immersed tunnel 1 to determine the soil layer distribution, physical and mechanical properties, and hydrogeological conditions of the construction area. This information is the basis for analyzing the interaction between the tunnel foundation 12 and the soil.

[0061] This process also includes collecting preliminary design, construction drawings, and historical construction records for immersed tunnel 1. By organizing and analyzing the above data, key information such as the structural type, geometric dimensions, material properties, foundation depth, and joint type of immersed tunnel 1 can be clarified. This information is necessary for calculating mechanical parameters such as the self-weight W and buoyancy R of the immersed tunnel in subsequent steps.

[0062] Hydrological and meteorological monitoring data were collected for the watershed where the existing immersed tunnel 1 is located. This data was used to analyze the dynamic changes in the water environment where the tunnel is located, such as the impact of flow velocity and tidal level changes on the scouring and siltation of the riverbed, thereby providing support for understanding the causes of defects and predicting the development trend of backfilling.

[0063] Uneven settlement data can be obtained through on-site monitoring. One specific method is to establish high-precision leveling observation points along the longitudinal and transverse directions inside the immersed tunnel 1. Periodic observations are conducted using precision leveling instruments or automated monitoring equipment to obtain precise values ​​of the current settlement of the tunnel floor slab 6, the settlement rate, and the settlement distribution curve along the tunnel axis.

[0064] Finally, the distribution of the backfill thickness 10 at the top of the pipe section at the defective site of the immersed tube foundation 12 was examined.

[0065] S2. Assess the existing immersed tunnel 1 for defects and treatment methods;

[0066] Specifically, in this embodiment, after completing step S1, step S2 is executed, which involves assessing the existing immersed tunnel 1's defects and determining corresponding treatment methods. This step is a crucial link connecting the preliminary survey and the subsequent construction. It directly utilizes the comprehensive database obtained in S1 as input and outputs a clear and executable repair technology path.

[0067] First, a systematic and comprehensive analysis is conducted on all the data collected and monitored in step S1, including geological data, engineering drawings, current structural status, hydrological conditions, and specific data on uneven settlement.

[0068] Subsequently, based on the above comprehensive analysis, the professional quality inspection unit conducted an assessment and evaluation of the overall quality and safety status of the existing immersed tunnel 1. The purpose of this assessment and evaluation was to determine the severity of the current defects and to provide a scientific basis for selecting the most appropriate repair methods.

[0069] Furthermore, the core of this step lies in establishing a decision-making process based on the severity of the damage to determine the subsequent technical solutions to be implemented. This decision-making process is based on the uneven tunnel submersion data obtained from monitoring in S1 and compared with a preset settlement control threshold.

[0070] For example, the settlement control threshold can be set to 5 mm. When the analysis results show that the maximum uneven settlement value of the tunnel floor slab 6 has exceeded the 5 mm threshold, it is determined that the defect has a significant impact on structural safety.

[0071] By performing the above assessment and decision-making steps, the most appropriate repair techniques can be matched according to the actual severity of the disease.

[0072] S3. Determine the location of the borehole at the defect site of the existing immersed tunnel 1.

[0073] Specifically, after completing the defect assessment and method decision in step S2, the embodiment of the present invention proceeds to step S3, which involves determining the borehole location at the defect site in the existing immersed tunnel 1. This step is the precise spatial positioning step for the subsequent directional grouting and lifting process, and its execution result directly determines the success or failure and safety of the lifting operation.

[0074] In one specific implementation, this step first involves analyzing the foundation defects of the immersed tunnel 1 through on-site scanning. For example, before the implementation of the scheme, ground-penetrating radar or other non-destructive testing technologies can be used to scan the defective tunnel segments identified in S2. The purpose is to accurately detect and analyze the specific scope and morphology of the impact of existing foundation settlement defects of the immersed tunnel 1.

[0075] Subsequently, based on the basic defect distribution data obtained from the above-mentioned on-site scanning analysis, the drilling location of directional drilling 7 was determined. That is, the axis of the determined horizontal grouting hole 2 should be located at a predetermined distance h1 below the bottom surface of the tunnel floor slab 6.

[0076] Furthermore, in one embodiment of the present invention, the preset distance h1 is set to 800mm. This distance h1 = 800mm is set based on mechanical considerations regarding the effect of grouting pressure. This distance ensures that the pressure sphere formed by the grout in the foundation soil can act evenly and effectively on the lower surface of the tunnel floor slab 6.

[0077] This distance setting avoids potential localized stress concentration damage to the tunnel floor slab structure caused by grouting points being too close (less than 500mm). Simultaneously, it avoids the problems of low grouting lifting force transmission efficiency and difficulty in precise control of the lifting process caused by grouting points being too far (greater than 1500mm).

[0078] S4. Determine the grouting pressure for a single hole using the grouting pressure calculation formula;

[0079] Specifically, after accurately determining the borehole location in step S3, the embodiment of the present invention proceeds to step S4. This step aims to provide a theoretical mechanical basis and key construction control parameters for subsequent lifting operations by establishing a mechanical equilibrium model and applying the grouting pressure calculation formula.

[0080] The distribution of the backfill thickness 10 at the top of the tunnel section at the defective location was analyzed using on-site testing methods. This test result is derived from step S1 and is a direct application of the data obtained in step S1. In an exemplary working condition, it can be assumed that the measured backfill thickness h3 is greater than 1m, and dredging is planned, with a dredging thickness h of 1m.

[0081] Subsequently, a vertical mechanical equilibrium model of the pipe section to be lifted was established. The physical significance of this model is that the total lifting force P generated by directional grouting must be sufficient to overcome the effective gravity of the immersed pipe in the current environment, that is, the difference between the self-weight W of the immersed pipe and the buoyancy R, and additionally overcome the self-weight R of the silt covering it.

[0082] Based on the above mechanical equilibrium model, the calculation formula for the total grouting lift force is derived as follows:

[0083] P = W - R + f;

[0084] In the formula, P represents the grouting pressure, W represents the weight of the submerged tube, R represents the buoyancy, and f represents the weight of the silt.

[0085] After determining the required theoretical total grouting force P, the average force distributed to a single directional grouting hole 2 is further calculated. The formula for calculating the average force per hole is as follows:

[0086]

[0087] In the formula, n represents the number of grouting holes, and ρ represents the grouting pressure of a single grouting hole.

[0088] S5. Determine the number and spacing of directional grouting holes 2;

[0089] Specifically, after calculating the theoretical grouting force in step S4, the embodiment of the present invention proceeds to step S5. This step aims to determine the specific number and spatial arrangement of the grouting holes 2 used for directional grouting, thereby applying the macroscopic mechanical requirements calculated in step S4.

[0090] Therefore, the arrangement of the directional grouting holes 2 is based on a preliminary theoretical assumption, namely, the design is initially based on the diffusion radius of the grout in the foundation soil being 1.25m.

[0091] To facilitate precise control of the construction process, this step adopts a strategy of multi-segment division and segmented grouting. For example, the damaged pipe segment to be treated is divided into several standard segments along its longitudinal direction, and the length of each segment can be set to 15m.

[0092] Within each 15m standard section, the arrangement of directional grouting holes 2 includes two rows of parallel grouting holes arranged transversely along the tunnel. Within the same row, the longitudinal spacing (H3) between adjacent directional grouting holes 2 is set at 1.5m. This spacing of H3 = 1.5m matches the initially considered diffusion radius of 1.25m, aiming to ensure that the pressure influence range formed by adjacent grouting holes can effectively overlap, thereby creating a continuous and uniform lifting surface below the tunnel floor slab 6.

[0093] Ten grouting pipes 4 can be designed and arranged from the external working platform 3 to grout into the directional grouting hole 2.

[0094] With the above layout scheme, the total number n of directional grouting holes 2 used for the lifting operation can be determined. This number n is a key parameter necessary for the formula to calculate the single-hole grouting pressure ρ in step S4, thus establishing a direct link from engineering layout to mechanical calculation.

[0095] S6. Determine the grouting sequence of directional grouting hole 2;

[0096] Specifically, after completing the arrangement of the directional grouting holes 2 in step S5, the embodiment of the present invention proceeds to step S6. This step aims to clarify the grouting sequence of the directional grouting holes 2, and through a preset construction sequence that conforms to mechanical principles, ensure the safety, stability, and controllability of subsequent lifting operations.

[0097] The general sequence of directional grouting follows the principle of "from the outside to the inside". That is, grouting is first performed on the directional grouting hole 2 located on the outside of the tunnel cross section, and then grouting is performed on the directional grouting hole 2 on the inside.

[0098] Specifically, the outer grouting adopts an integral grouting method. The purpose of this step is to pre-reinforce and improve the soil around and below the immersed tube foundation 12, thereby forming a "retaining structure" with higher strength and lower permeability on the periphery of the raised area. This structure can effectively constrain the diffusion range of the subsequent inner main raised grout and more effectively concentrate the grouting energy on the area below the tunnel floor 6.

[0099] After the outer grouting is completed and an effective enclosure is formed, grouting begins on the inner directional grouting holes 2. The grouting sequence on the inner side further follows the method of first constructing the side wall holes, and then constructing the centerline hole.

[0100] When grouting the directional grouting holes 2 below the inner two sidewalls, the grouting pressure or grouting range should not be too large, as this may damage the existing tunnel floor slab 6 framework. The purpose of this is to avoid the potential damage to the existing immersed tube foundation 12 structural framework due to excessively concentrated or uneven initial lifting force, thereby achieving a gradual loading of the tunnel structure through grouting.

[0101] After the sidewall holes on both sides are completed and effective bearing capacity is formed through grouting, providing stable initial support for the tunnel structure, the directional grouting hole 2 located below the center line of the tunnel is then constructed.

[0102] Since the tunnel has been supported on both sides at this time, the overall stress state of the structure is more favorable. Therefore, when constructing the intermediate directional grouting hole 2, its grouting pressure can be appropriately increased to complete the main lifting task.

[0103] S7. Directional grouting raises the tunnel floor slab 6.

[0104] Specifically, guided by the preset sequence planned in step S6, the embodiment of the present invention then executes step S7. This step is the core execution link of the present invention for repairing uneven settlement defects in the immersed tunnel 1. Its purpose is to accurately raise the settled tunnel floor slab 6 to a predetermined elevation through directional grouting.

[0105] The execution process strictly controls three key parameters: grouting volume, grouting pressure, and tunnel elevation, thus forming a closed-loop feedback control system. The grouting operation adopts a one-time grouting method, that is, the grouting process for a single directional grouting hole 2 is continuous until the control target is achieved.

[0106] During the grouting process, the grouting pressure applied through the grouting pipe 4 is strictly controlled within the construction control value corresponding to the theoretical grouting pressure calculated in step S4. The grouting pressure is applied in a gradually increasing manner to ensure a smooth loading of the tunnel structure and avoid instantaneous impact.

[0107] In sync with the application of grouting pressure, the automated monitoring system deployed in step S1 continuously monitors the lifting of the tunnel floor slab 6 in real time. This real-time monitoring data serves as a feedback signal, used to compare with preset control targets.

[0108] The preset control objective is that when the lifting amount of the tunnel floor slab 6 reaches within the ±5mm tolerance range of its design elevation, the lifting is considered complete. At this point, the control system immediately issues a command to stop the grouting operation of the corresponding grouting hole 2 in that area.

[0109] Furthermore, this embodiment also includes a supplementary adjustment mechanism. If, after a grouting operation, the monitoring system shows that the uplift of the area has not reached the design elevation within ±5mm, a supplementary grouting procedure is initiated to continue grouting the area until the uplift finally meets the design requirements.

[0110] S8. After directional grouting, there is still some void 9 in the immersed tunnel 1. Grouting is performed on the bottom slab 6 at the part of the void 9:

[0111] Specifically, after the directional grouting and lifting operation in step S7 is completed, the embodiment of the present invention proceeds to step S8. This step is a supplementary repair step, the purpose of which is to address any remaining voids 9 that may remain between the immersed tunnel 1 and the newly formed foundation after directional grouting, thereby ensuring that the tunnel foundation receives full and gap-free support.

[0112] When it is detected that there is still a part of void 9 in the immersed tunnel 1 after directional grouting, it is necessary to open a hole in the tunnel bottom slab 6 corresponding to the local void area 9 and carry out filling grouting.

[0113] To ensure precise control of the grouting process, the grouting operation in the local void zone 9 still needs to be divided into multiple sections for the local void areas of the pipe section, and grouting should be carried out in sections to ensure the uniformity and compactness of the grout filling.

[0114] To implement this supplementary grouting, several grouting holes 5 need to be installed on the tunnel floor slab 6. In a specific layout scheme, three rows of grouting holes 5 are installed along the transverse direction of the tunnel in each pipe segment to be treated. These three rows of grouting holes are located one row at the tunnel centerline and one row each near the two sidewalls.

[0115] In the same row, the spacing H between adjacent bottom slab grouting holes 5 along the tunnel longitudinal direction is set at 2.5m. This spacing is designed to ensure that the grout diffusion range of adjacent grouting holes can effectively overlap, thereby achieving complete coverage of the voided area.

[0116] To protect existing facilities inside the tunnel, the location of the grouting hole 5 in the bottom slab at the edge of the sidewall needs to be specially designed. The opening position should maintain a safe clearance of not less than H5 = 50cm from the edge of components such as water ditches and cable trenches 8 inside the tunnel.

[0117] Furthermore, this embodiment also includes an adaptive adjustment mechanism. If the diffusion radius of the grout is found to be insufficient during the actual grouting process, supplementary grouting can be carried out by increasing the density of grouting holes between the original holes to ensure the final filling effect.

Claims

1. A method for treating uneven settlement defects in the foundation of an operational immersed tunnel, characterized in that, Includes the following steps: S1. Preliminary preparations, including: Geological data survey and data collection of existing immersed tunnels (1); Hydrological and meteorological monitoring data of the basin where the immersed tunnel (1) is located; Monitoring yielded data on uneven settlement of the tunnel; Distribution of backfill thickness at the top of the tunnel section (1) with defects; S2. Assess existing immersed tunnel (1) defects and determine treatment methods; S3. Determine the location of the borehole at the defect site of the existing immersed tunnel (1); S4. Determine the grouting pressure for a single hole using the grouting pressure calculation formula; S5. Determine the number and spacing of directional drilling (7) and directional grouting holes (2); S6. Clarify the grouting sequence of directional drilling (7) and directional grouting hole (2); S7. Directional grouting raises the tunnel floor (6) to the design elevation; S8. After the immersed tunnel (1) is raised to the design elevation by directional grouting, there is still some void (9) in the tunnel floor slab (6). Grouting is performed on the void (9) in the tunnel floor slab (6).

2. The method for treating uneven settlement defects in the foundation of an operational immersed tunnel according to claim 1, characterized in that, The geological data collection in step S1 mainly includes conducting a survey of the geological conditions within the scope of the immersed tunnel (1), determining the soil layers and hydrogeological conditions of the construction area; collecting preliminary design and construction drawings of the immersed tunnel (1), construction data, clarifying the structural type of the immersed tunnel (1), foundation burial depth data, and the thickness of backfilling at the top of the damaged pipe section.

3. The method for treating uneven settlement defects in the foundation of an operational immersed tunnel according to claim 1, characterized in that, In step S2, the quality assessment of the immersed tunnel (1) is mainly an assessment of the current quality of the immersed tunnel (1) by a professional quality inspection unit, checking the specific data of foundation settlement, assessing and identifying the defects of the immersed tunnel foundation (12), and determining the treatment method.

4. The method for treating uneven settlement defects in the foundation of an operational immersed tunnel according to claim 1, characterized in that, In step S3, the location of the horizontal directional drilling hole is determined by analyzing the foundation defects of the immersed tunnel (1) through on-site scanning. Before implementing the plan, the scope of the disease was first detected and analyzed by scanning. Then, a hole was drilled at a distance of h1 = 800 mm from the bottom of the tunnel floor (6) to determine the location of the horizontal directional drilling (7) hole.

5. The method for treating uneven settlement defects in the foundation of an operational immersed tunnel according to claim 1, characterized in that, In step S4, the distribution of the backfill thickness (11) at the top of the tunnel section at the defect site is analyzed by on-site testing. The backfill thickness (11) is set to h3>1m, and the dredging thickness is set to (10) with h=1m. The grouting pressure is then determined. The formula for calculating grouting pressure is: P = W - R + f; The pressure in a single orifice is: In the formula, P represents the grouting pressure, W represents the weight of the submerged tube, R represents the buoyancy, f represents the weight of the silt, n represents the number of grouting holes, and ρ represents the grouting pressure of a single grouting hole.

6. The method for treating uneven settlement defects in the foundation of an operational immersed tunnel according to claim 1, characterized in that, The determination of the number and spacing of directional grouting holes (2) in step S5 specifically includes the following steps; When the diffusion radius of the grout cannot be determined, the directional grouting holes (2) are initially arranged according to a diffusion radius of 1.25m. Multiple segments are used for grouting, with each segment consisting of 15m sections and two rows of directional grouting holes (2). Each work platform (3) is designed with 10 grouting holes (2). The spacing between the grouting pipes (2) is arranged according to H3 = 1.5m. If the diffusion radius of the grout is insufficient during the actual grouting process, the directional grouting holes (2) are densified for supplementary grouting.

7. The method for treating uneven settlement defects in the foundation of an operational immersed tunnel according to claim 1, characterized in that, In step S6, directional grouting is performed by grouting the outer side first and then the inner side, and the inner side grouting is performed by grouting the wall edge first and then the middle. The grouting sequence of the directional grouting hole (2) is from the outside to the inside. The grouting of the outside adopts the overall grouting method to reinforce the soil of the sinking pipe foundation (12). The inner grouting adopts the following method: first, make the side wall holes on both sides, and then make the center line hole in the middle. The grouting pressure or grouting range of the directional grouting holes (2) on both sides should not be too large. After the holes on both sides are completed and provide bearing capacity, the grouting pressure can be increased when making the directional grouting hole (2) in the middle.

8. A method for treating uneven settlement defects in the foundation of an operational immersed tunnel according to claim 7, characterized in that, In step S7, the directional drilling (7) grouting strictly controls the grouting pressure of a single hole and the lifting amount of the tunnel floor (6); One-time grouting is adopted, and the grouting pressure of the working platform (3) is controlled within the calculated ρ grouting pressure. During grouting, the pressure is gradually increased from small to large. Grouting should be stopped when the amount of lifting of the tunnel floor slab (6) reaches ±5mm of the design elevation; If the design elevation is not reached within ±5mm, continue grouting until the design requirements are met.

9. A method for treating uneven settlement defects in the foundation of an operational immersed tunnel according to claim 1, characterized in that, In step S8, after directional grouting, the tunnel bottom plate (6) of the immersed tunnel (1) still has local voids (9), and it is necessary to open holes in the tunnel bottom plate (6) of the local void area (9) for grouting. During grouting, it is still necessary to divide the local void area (9) of the pipe section into multiple sections and grout in sections.

10. A method for treating uneven settlement defects in the foundation of an operational immersed tunnel according to claim 1, characterized in that, In step S8, three rows of grouting holes (5) are set in the local void area (9) of the tunnel bottom plate (6). One row is set on each side wall and one row is set on the center line. The spacing of each row of bottom plate grouting holes (5) is arranged at H=2.5m. The grouting holes at the edge of the side wall are 50cm away from the water ditch and cable trough (8). When the grout diffusion radius is insufficient during the actual grouting process, the grouting holes are densified for supplementary grouting.

Images