A method of treating a tunneling soil cave

Abstract

This application relates to a method for treating karst caves in tunnels, belonging to the field of underground structure engineering technology. The method includes dividing the existing tunnel floor slab into multiple construction sections; in the current construction section, multiple construction holes are opened in the floor slab using a skip-section method, with the size of the construction holes configured to provide operational space for rebar splicing and waterproofing layer repair; grouting is performed into the soil beneath the existing tunnel through the construction holes; after the grouting is deemed satisfactory, the floor slab rebar and waterproofing layer at the construction holes are repaired; after completing the treatment of the current construction section, the process is repeated in the next construction section until all construction sections are treated. By opening relatively large construction holes and specifically configuring sufficient operational space for rebar splicing and waterproofing layer repair, even if the floor slab rebar is cut during construction, standardized splicing operations and waterproofing layer restoration can still be performed using this space.

Description

Technical Field

[0001] This application relates to the field of underground structure engineering technology, and in particular to a method for treating karst caves in tunnels. Background Technology

[0002] With the rapid development and utilization of underground space in my country, underground rail transit facilities in urban centers are becoming increasingly dense. However, the increasing intensity of underground space development has led to more and more new municipal tunnels, subway station sections, underground pipelines, and other infrastructure interacting with existing rail transit facilities. In limestone areas, some newly constructed tunnels must run parallel to existing tunnels due to route constraints, making the treatment of karst caves in the new tunnels a challenge.

[0003] Traditional methods for treating karst caves require drilling numerous vertical boreholes on the ground, including exploration holes, grouting holes, and ventilation holes. Since the new tunnel is located beneath an existing tunnel, these boreholes must be drilled through the existing tunnel floor. The borehole diameter is 100-200 mm, with the densest arrangement being a staggered pattern with a 2-meter spacing. The existing tunnel reinforcement is typically arranged in two layers, horizontally and vertically, with a spacing of 150 mm. In actual construction, it is difficult for the boreholes used for karst cave treatment to avoid the existing reinforcement, easily cutting off the floor slab reinforcement and damaging the waterproofing layer. Due to the small diameter of the boreholes, the cut floor slab reinforcement and waterproofing layer are difficult to repair, severely weakening the structural safety and durability of the existing tunnel. If the existing tunnel floor is completely demolished and repaired, it would completely disrupt traffic, severely impacting public transportation, and incurring enormous costs and a long construction period. Summary of the Invention

[0004] This application provides a method for treating karst caves in tunnels, which solves the technical problems in related technologies where small-diameter drilling easily cuts through steel bars and is difficult to repair when treating karst caves in existing tunnel floor slabs, affecting structural safety, while the overall demolition of the floor slab leads to traffic disruption and huge costs.

[0005] A method for treating karst caves in tunnels is provided, comprising: dividing the existing tunnel floor into multiple construction sections; in the current construction section, opening multiple construction holes in the floor using a skip-section method, wherein the size of the construction holes is configured to provide operating space for rebar splicing and waterproofing layer repair; grouting the soil below the existing tunnel through the construction holes; after the grouting is deemed satisfactory, repairing the floor rebar and waterproofing layer at the construction holes; after completing the treatment of the current construction section, switching to the next construction section and repeating the above steps until all construction sections are treated.

[0006] In some embodiments, the floor of the existing tunnel is divided into multiple construction sections, specifically including: setting up temporary barriers in the left and right tunnels of the existing tunnel so that two half-width construction sections are formed in each tunnel.

[0007] In some embodiments, one half of the construction section within each tunnel is designated as a temporary construction section, and the other half is designated as a temporary traffic diversion section.

[0008] In some embodiments, multiple construction holes are opened on the base plate in the current construction section using a skip-section method. Specifically, this includes: conducting detailed and supplementary exploration of karst caves in the current construction section; determining the opening position of the construction holes based on the location of the karst caves revealed by the exploration results; and opening multiple construction holes at the determined opening positions.

[0009] In some embodiments, the plurality of construction holes include pre-drilling holes and post-drilling holes. Grouting is performed on the soil below the existing tunnel through the pre-drilling holes, and then grouting is performed on the soil below the existing tunnel through the post-drilling holes.

[0010] In some embodiments, the construction hole is rectangular in shape, and the side length of the construction hole ranges from 1.5 meters to 2.5 meters.

[0011] In some embodiments, grouting is performed on the soil beneath the existing tunnel through the construction hole, specifically including: drilling a probing hole in the construction hole to detect the boundary of the karst cave; drilling a venting hole in the construction hole to expel air from the karst cave; and drilling a grouting hole in the construction hole to inject grouting material into the soil beneath the existing tunnel to fill the karst cave.

[0012] In some embodiments, the probing holes, venting holes, and grouting holes are drilled using vertical drilling and / or oblique drilling methods.

[0013] In some embodiments, the repair of the bottom slab reinforcement and waterproof layer at the construction hole includes: cleaning the hole opening to identify and expose the ends of the reinforcement bars; welding the exposed reinforcement bars with equal strength; applying a second waterproof layer at the construction hole, wherein the repair material of the waterproof layer is consistent with the original waterproof layer material of the existing tunnel; and pouring concrete to restore the bottom slab.

[0014] In some embodiments, the method further includes: during the construction of the karst cave treatment project, real-time monitoring of the settlement and deformation data of the existing tunnel; when the settlement and deformation data exceeds a preset threshold, suspending construction and taking reinforcement measures.

[0015] The beneficial effects of the technical solution provided in this application include: This application provides a method for treating karst caves in tunnels, dividing the existing tunnel floor into multiple construction sections and opening large-sized construction holes in the current section. This large-sized design is specifically configured to provide ample operating space for rebar splicing and waterproofing layer repair. During construction, grout is injected into the soil below through the construction holes. Once qualified, the floor rebar and waterproofing layer at the hole are immediately repaired, and then the process is repeated in the next section. By opening large-sized construction holes and specifically configuring ample operating space for rebar splicing and waterproofing layer repair, even if the floor rebar is cut during construction, technicians can use this space to perform standardized splicing operations and waterproofing layer restoration. This avoids the defects of traditional small-diameter drilling, which cannot avoid dense rebar mesh, resulting in the cutting of rebar and damage to the waterproofing layer, which is difficult to repair. This significantly ensures the structural safety and durability of the existing tunnel. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall process provided for an embodiment of this application; Figure 2 A flowchart illustrating step 2 is provided for an embodiment of this application; Figure 3 A flowchart illustrating step 3 is provided for an embodiment of this application; Figure 4 This is a flowchart illustrating step 4, provided as an embodiment of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] This application provides a method for treating karst caves in tunnels, which can solve the technical problems in related technologies where small-diameter drilling easily cuts through steel bars and is difficult to repair when treating karst caves in existing tunnel floor slabs, affecting structural safety, while the overall demolition of the floor slab leads to traffic disruption and huge costs.

[0020] Reference Figure 1-4 A method for treating karst caves in tunnels, comprising: S1: The existing tunnel floor slab is divided into multiple construction sections. This is achieved by setting up temporary barriers along the centerline of the left and right tunnels, creating two half-width construction sections within each tunnel. These two half-width sections can be constructed separately. One half-width section within each tunnel is designated as a temporary construction section, and the other as a temporary traffic diversion section. Specifically, the two adjacent half-width sections of the two tunnels are designated as temporary traffic diversion sections. During construction, the temporary construction section can be constructed first, while the temporary traffic diversion section provides traffic diversion, ensuring that at least half of the road surface remains open for vehicle passage throughout the construction period. This avoids complete traffic disruption caused by the complete removal of the floor slab, significantly reducing social impact and economic losses. Furthermore, by limiting the scope of each construction operation, the unconstructed half-width of the floor slab can continue to bear the loads from the tunnel superstructure and vehicle dynamic loads, maintaining the overall structural stability and load-bearing capacity of the existing tunnel during construction and preventing the risk of settlement due to large-scale floor slab failure.

[0021] S2: In the current construction section, multiple construction holes are drilled in the base slab using a skip-work method. The size of these holes is configured to provide operational space for rebar splicing and waterproofing layer repair. This skip-work method ensures an effective load transfer path in areas without holes, preventing abrupt changes in stiffness or stress concentration caused by continuous drilling. Furthermore, the construction holes, providing space for rebar splicing and waterproofing layer repair, are used to create additional repair space, thus transforming unavoidable structural damage in traditional methods into repairable temporary damage. This approach avoids the structural safety hazards caused by small-diameter drilling that cuts off rebar and cannot be repaired, ensuring that the structural bearing capacity of the repaired base slab is not lower than the original level. Secondly, it provides reliable conditions for waterproofing repair.

[0022] Specifically: In the current construction section, multiple construction holes are opened on the base plate using a skip-work method, including: S20: Conduct detailed and supplementary exploration of karst caves in the current construction section. The detailed and supplementary exploration eliminates the uncertainty of underground geological conditions, provides accurate data support for subsequent construction, avoids blind construction due to unclear geology, and controls the risk of missed or ineffective grouting from the source. S21: Based on the location of the karst caves revealed by the survey results, the opening positions of the construction holes are determined. The opening positions are determined according to the survey results to ensure that the construction holes are only set in the necessary areas where there is a risk of karst caves. This minimizes the number of openings in the existing tunnel floor, effectively protects the structural integrity of the floor in areas that do not require treatment, and significantly reduces the weakening of the overall rigidity of the tunnel due to excessive openings. Furthermore, the combination of survey and skip-section method further optimizes the distribution of openings and avoids stress concentration. S22: Multiple construction holes were drilled at the designated locations to ensure a high degree of alignment between the grouting channel and the spatial position of the karst cave, improving the density and efficiency of the grout filling and preventing grouting blind spots caused by hole position deviations. In summary, this scheme effectively balances the contradiction between engineering reinforcement needs and existing structural protection while ensuring the quality of karst cave treatment, reducing material waste and construction costs, and achieving a balance of safety, economy, and efficiency. It is particularly suitable for existing operational tunnels sensitive to structural deformation.

[0023] Furthermore, in this step, multiple construction holes are involved, including pre-drilling and post-drilling. Grouting is performed on the soil beneath the existing tunnel through the pre-drilling holes, followed by grouting through the post-drilling holes. Dividing the construction holes into pre-drilling and post-drilling groups and implementing step-by-step grouting achieves phased release of construction risks and multiple guarantees for structural safety. Secondly, it ensures grouting quality and controllability. Step-by-step grouting avoids the superposition of grouting pressure and grout cross-flow caused by simultaneous operation of multiple holes, ensuring the orderly diffusion and filling of grout in the soil, improving the compaction of the karst cave treatment. Simultaneously, the pre-drilling section can serve as a test section, verifying the rationality of parameters by monitoring tunnel settlement and deformation during the grouting process. If abnormalities are found, the subsequent construction plan can be adjusted in a timely manner. Finally, it reserves emergency remedial space. If the pre-drilling effect is not up to standard, the post-drilling holes can serve as supplementary grouting channels for secondary reinforcement, providing redundant means for quality remediation. In summary, this solution significantly improves the safety, reliability, and quality control of existing tunnel reinforcement construction under complex geological conditions.

[0024] In this application, the construction hole is rectangular in shape, with a side length ranging from 1.5 meters to 2.5 meters. The rectangular shape conforms to the orthogonal grid arrangement of the existing tunnel floor reinforcement, facilitating the alignment and welding of the cut sections of the reinforcement. Furthermore, the straight edges are more conducive to the standardized overlapping and sealing of the waterproof membrane compared to a circular shape, reducing the risk of leakage. The side length range of 1.5 to 2.5 meters is set based on the critical values ​​of ergonomic working space requirements and the structural mechanical bearing capacity limits. First, the lower limit of 1.5 meters ensures that workers have sufficient internal operating space to easily complete the equal-strength welding of the reinforcement and the multi-layer application of the waterproof layer, completely overcoming the defect in the prior art where small-diameter holes could not be repaired, leading to structural weakening. Second, the upper limit of 2.5 meters limits the degree of weakening of the floor slab stiffness by a single hole, preventing stress concentration, local collapse, or excessive deformation due to excessively large openings, thus ensuring the tunnel's load-bearing capacity and operational safety during construction.

[0025] S3: After the construction hole is opened, this application involves grouting into the soil beneath the existing tunnel through the construction hole. The specific steps include: S30: Drill edge detection holes inside the construction hole to detect the boundary of the karst cave. S31: Ventilation holes are drilled in the construction hole to allow air to escape from the karst cave. S32: Grouting holes are drilled in the construction hole, and grouting material is injected into the soil below the existing tunnel through the grouting holes to fill the karst cavities.

[0026] By arranging boreholes with different functions within a single construction hole space, a dual guarantee mechanism for grouting quality and structural safety is constructed. The edge probing hole is used to accurately delineate the spatial boundary of the karst cave, solving the technical problem of unclear grouting range and avoiding grout loss or filling of blind spots. The venting hole uses a gas discharge channel to eliminate air resistance in the hole, ensuring that the grout fully fills the dead corners of the karst cave under gravity and pressure, and at the same time serves as a visual indicator of grouting fullness, stopping as soon as grout is seen. The grouting hole focuses on efficient grout delivery.

[0027] In this application, the exploration holes, ventilation holes, and grouting holes are installed using vertical drilling and / or inclined drilling. This combination of vertical and inclined drilling enables precise treatment of irregular karst cavities. The vertical drilling offers the advantages of the shortest path, minimal construction deviation, and high efficiency. It serves as the main channel for rapid direct grouting reinforcement of the soil directly below, ensuring rapid restoration of the foundation's bearing capacity and contributing significantly to construction efficiency. The inclined drilling expands the detection and grouting range, reaching areas inaccessible to vertical drilling, such as lateral extensions, bottom depressions, and top air pockets, effectively eliminating grouting dead zones and ensuring unobstructed air release. The synergistic effect of this combination is that vertical drilling ensures both construction efficiency and the quality of the main filling, while the inclined drilling addresses the issue of the integrity of the filling in irregular karst cavities. This combination method makes full use of the operating space provided by the large-sized construction holes, and the drilling angle ratio can be dynamically adjusted according to the survey results. This significantly improves the grouting density and uniformity, prevents differential settlement caused by local incomplete filling, and avoids the risk of concentrated grouting pressure that may be caused by a single drilling method. It comprehensively improves the reliability and structural safety of the soil reinforcement under the existing tunnel.

[0028] S4: After the grouting treatment is deemed satisfactory, the bottom slab reinforcement and waterproof layer at the construction hole shall be repaired, specifically including: S40: Clean the opening to identify and expose the ends of the reinforcing bars; S41: Perform equal-strength welding on exposed reinforcing bars; S42: A second waterproof layer is applied at the construction hole, and the repair material of the waterproof layer is the same as the original waterproof layer material of the existing tunnel. S43: Pour concrete to restore the base slab.

[0029] Cleaning the boreholes removed concrete debris and rust, ensuring the cleanliness of the welded interface and providing a foundation for the quality of subsequent connections. The core function of equal-strength welding is to restore the mechanical transmission path of the reinforcing bars, ensuring that the yield strength and tensile strength at the repair site are not lower than the original design standards. This avoids the potential for permanent weakening of the structural bearing capacity caused by small-diameter drilled and cut reinforcing bars that cannot be repaired. The secondary application of consistent materials utilizes the chemical compatibility and thermal expansion coefficient matching of the same waterproofing material to ensure seamless overlap and long-term bonding reliability of the new and old waterproofing layers, eliminating the risk of interface leakage caused by material differences. Pouring concrete restores the geometric integrity, rigidity, and durability of the base slab.

[0030] The combined effects of this step are significant: it not only fully restores the safety and durability of the existing tunnel structure, avoiding the risks of subsequent settlement, cracking or leakage caused by improper repair, but also verifies the necessity of providing operating space through large-sized construction holes, proves the reversibility and reliability of the method under the premise of ensuring operational safety, achieves the technical goal of non-destructive repair of existing structures through engineering reinforcement, and significantly improves the service life and maintenance economy of existing tunnels.

[0031] S5: After completing the processing of the current construction section, this application switches to the next construction section and repeats the above steps until all construction sections are processed. First, temporary barriers are set up at the center lines of the left and right tunnels of the existing tunnel, dividing each tunnel into two half-sections of construction. The two adjacent half-sections of construction are divided into temporary construction sections, and the remaining half-section is used as a temporary traffic diversion section. Then, detailed exploration and supplementary exploration of karst caves are carried out in the temporary construction sections. Based on the exploration results, the preliminary construction holes are opened in a skip-section manner. Vertical or oblique exploration holes, ventilation holes and grouting holes are drilled through the holes for grouting. After the grouting is qualified, the hole openings are cleaned to expose the ends of the reinforcing bars. The reinforcing bars are welded with equal strength, a second waterproof layer of the same material as the original is laid, and concrete is poured to restore the bottom slab. After all the initial construction holes have been repaired, subsequent construction holes will be opened in the remaining locations of the section. The drilling, grouting, and bottom slab repair steps described above will be repeated to complete the full-section treatment of the current temporary construction section. Subsequently, the temporary barriers will be removed to switch traffic diversion. The repaired temporary construction section will be opened as a traffic diversion route, while the original temporary traffic diversion section will be closed as a new temporary construction section. The above steps will be repeated in the same order: first, complete the drilling and grouting repair of the initial construction holes, and then complete the drilling and grouting repair of the subsequent construction holes. This process will continue until all construction sections have been treated. Finally, all temporary facilities will be removed to restore normal tunnel operation.

[0032] The method for treating karst caves in this application also includes: real-time monitoring of the settlement and deformation data of the existing tunnel during the construction of the karst cave treatment project; when the settlement and deformation data exceeds a preset threshold, construction is suspended and reinforcement measures are taken. Using the structural response of the existing tunnel as a constraint on construction progress, and by monitoring the settlement and deformation data in real time, the subtle impacts of construction disturbances such as grouting pressure and bottom slab openings on the tunnel structure can be captured in a timely manner, achieving quantifiable risk management. The benefits of suspending construction and taking reinforcement measures when the data exceeds the preset threshold are significant: First, a quantifiable safety red line is established, avoiding the blind reliance on experience-based judgments and ensuring that tunnel deformation is strictly controlled within the allowable range of design specifications, preventing cumulative deformation from causing structural damage; second, the timely suspension mechanism buys valuable time for risk management, prevents the situation from worsening, and ensures that reinforcement measures can be effectively implemented.

[0033] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0034] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0035] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method of treating a solution cave, comprising: It includes: The existing tunnel floor was divided into multiple construction sections; In the current construction section, multiple construction holes are opened on the base plate using a skip-work method. The size of the construction holes is configured to provide operating space for rebar splicing and waterproofing layer repair. Grouting is performed into the soil beneath the existing tunnel through the construction hole; After the grouting treatment is deemed satisfactory, the bottom slab reinforcement and waterproof layer at the construction hole shall be repaired. After completing the processing of the current construction section, switch to the next construction section and repeat the above steps until all construction sections have been processed.

2. A method of treating a solution cave according to claim 1, wherein: The existing tunnel floor is divided into multiple construction sections, specifically including: Temporary barriers were set up in the left and right tunnels of the existing tunnel to create two half-width construction sections in each tunnel.

3. The method for treating karst caves in tunnels as described in claim 2, characterized in that: One half of the construction section within each tunnel will be designated as a temporary construction section, and the other half as a temporary traffic diversion section.

4. The method for treating karst caves in tunnels as described in claim 1, characterized in that: In the current construction section, multiple construction holes are opened on the base plate using a skip-work method, specifically including: Conduct detailed and supplementary investigations of karst caves within the current construction area; Based on the location of the karst caves revealed by the survey results, the location of the construction hole can be determined. Multiple construction holes are made at the determined opening locations.

5. The method for treating karst caves in tunnels as described in claim 4, characterized in that: The multiple construction holes include pre-drilled holes and post-drilled holes. Grouting is performed on the soil below the existing tunnel through the pre-drilled holes, and then grouting is performed on the soil below the existing tunnel through the post-drilled holes.

6. The method for treating karst caves in tunnels as described in claim 4, characterized in that: The construction hole is rectangular in shape, and the side length of the construction hole ranges from 1.5 meters to 2.5 meters.

7. The method for treating karst caves in tunnels as described in claim 1, characterized in that: Grouting is performed into the soil beneath the existing tunnel through the construction hole, specifically including: Exploration holes are drilled inside the construction hole; these exploration holes are used to detect the boundary of the karst cave. Ventilation holes are drilled inside the construction hole to allow air to escape from the slurry cave. Grouting holes are drilled in the construction hole, and grouting material is injected into the soil below the existing tunnel through the grouting holes to fill the karst cavities.

8. The method for treating karst caves in tunnels as described in claim 7, characterized in that: The probing holes, venting holes, and grouting holes are drilled using vertical drilling and / or oblique drilling methods.

9. The method for treating karst caves in tunnels as described in claim 1, characterized in that: Repairing the bottom slab reinforcement and waterproofing layer at the construction hole, specifically including: Clean the opening to identify and expose the ends of the reinforcing bars; Exposed reinforcing bars are welded with equal strength. A second waterproof layer is applied at the construction hole, and the repair material of the waterproof layer is the same as the original waterproof layer material of the existing tunnel. Pour concrete to restore the base slab.

10. The method for treating karst caves in tunnels as described in claim 1, characterized in that: Also includes: During the construction of the karst cave treatment project, the settlement and deformation data of the existing tunnel were monitored in real time. When the settlement deformation data exceeds the preset threshold, construction is suspended and reinforcement measures are taken.

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