Construction treatment method for horseshoe-shaped standard section of composite waterproof coating

Abstract

The invention discloses a construction treatment method for a horseshoe-shaped standard section of a composite waterproof coating. The method comprises the steps that advance support treatment operation is carried out on arch surrounding rock; construction treatment operation of a small grouting guide pipe is carried out on the arch surrounding rock; the excavation section is divided into the upper half section and the lower half section, and the upper half section is excavated firstly according to the sequence from top to bottom; performing primary support on the upper half section to form an upper half section primary support layer; the lower half section is excavated; performing primary support on the lower half section to form a lower half section primary support layer; a tunnel inverted arch waterproof layer is installed on the lower half section initial supporting layer at the bottom of the tunnel, and secondary lining construction is conducted; and secondary lining construction is carried out on a tunnel arch wall at the top of the tunnel, and a composite waterproof layer is installed between the tunnel arch wall and the secondary lining at the top of the tunnel. According to the method, the waterproof performance is stable, and the durability and safety of the tunnel are improved.

Description

Technical Field

[0001] This invention relates to the field of tunnel waterproofing construction and treatment, and in particular to a method for constructing a horseshoe-shaped standard cross-section with a composite waterproof coating. Background Technology

[0002] The bench excavation method in tunnel construction is a commonly used excavation technique, particularly suitable for rock formations with poor stability. The core of the bench excavation technique is to excavate the tunnel cross-section in layers, forming a stepped shape, to improve construction safety and efficiency.

[0003] In tunnel excavation, creating various required cross-sectional shapes such as rectangles, ellipses, horseshoe shapes, double circles, and triple circles is an essential technical means. Among these, horseshoe-shaped cross-sections are most commonly used, especially in railway and highway tunnel construction. The characteristics of a horseshoe-shaped cross-section include: 1. The top of the horseshoe-shaped cross-section is arc-shaped, similar to the upper part of a horseshoe, which helps to distribute pressure and improve structural stability. 2. Structural stability: Due to its arched upper design, the horseshoe-shaped cross-section can better withstand the pressure of the overlying rock and soil, providing better structural stability. 3. Space utilization: Compared to circular cross-sections, horseshoe-shaped cross-sections provide more space in the vertical direction, which can improve space utilization in certain situations.

[0004] Studies have found that common construction methods in existing technologies often involve applying a simple waterproof coating directly after the support is completed, followed by secondary lining construction. This method cannot ensure the waterproofness of the horseshoe-shaped standard cross-section, thus affecting the quality of waterproofing and even construction safety. Summary of the Invention

[0005] The purpose of this invention is to provide a method for constructing a horseshoe-shaped standard cross-section of a composite waterproof coating, which solves the aforementioned technical problems pointed out in the prior art.

[0006] This invention provides a method for constructing a horseshoe-shaped standard cross-section of a composite waterproof coating, comprising the following steps:

[0007] S1. Perform advanced support treatment on the arch surrounding rock: carry out grouting small pipe construction treatment on the arch surrounding rock;

[0008] S2. Circular excavation of the upper section with core soil: Divide the excavation section into an upper section and a lower section. In the order of top to bottom, first excavate the upper section (then excavate the lower section in step S4).

[0009] S3. Implement initial support on the upper half section to form an initial support layer for the upper half section, and then construct a wall on this basis to form a tunnel arch wall.

[0010] S4. Excavate the lower half of the cross section;

[0011] S5. Implement initial support on the lower half of the cross section to form the initial support layer of the lower half of the cross section;

[0012] S6. At the bottom of the tunnel, above the initial support layer of the lower half section, install the tunnel invert waterproof layer and carry out secondary lining construction.

[0013] S7. Secondary lining construction shall be carried out at the tunnel arch wall at the top of the tunnel, and a composite waterproof layer shall be installed between the tunnel arch wall and the secondary lining at the top.

[0014] Preferably, as one possible implementation, the composite waterproof layer includes a waterproof membrane (or waterproof film) and a buffer layer.

[0015] Preferably, as one possible implementation, the waterproof membrane is coated with a composite waterproof coating.

[0016] Preferably, as one possible implementation, the composite waterproof coating is a quick-setting rubber asphalt waterproof coating.

[0017] Preferably, as one possible implementation, the construction treatment operation of grouting small guide pipes for the surrounding rock of the arch includes the following steps:

[0018] S11. Conduct grouting tests;

[0019] S12. Perform drilling and small guide pipe installation operations;

[0020] S13. Perform grouting treatment;

[0021] S14. After grouting is completed, the holes are sealed to prevent grout backflow and ensure stable and long-lasting grouting effect.

[0022] Preferably, as one possible implementation, the grouting test includes: conducting a grouting test in a similar stratum outside the tunnel before formal grouting to determine whether the current grouting parameters are reasonable; if reasonable, continuing with subsequent operations.

[0023] The drilling and small guide pipe installation process is as follows: Before drilling, the hole position is measured and marked out. If the current hole position measuring instrument determines that the position is accurate, after drilling, high-pressure air or water is used to clean and blow away the sand, dust and accumulated water inside the hole.

[0024] The grouting process is as follows: before grouting, the working face is sealed with sprayed concrete to prevent grout leakage; the accumulated material inside the pipe is flushed out first, and then grouting is performed; the grouting sequence is from bottom to top, and the grout is mixed with a mixer.

[0025] Preferably, as one possible implementation method, the initial support includes:

[0026] S31: Shotcrete: Concrete is sprayed onto the excavated surface using a spraying device to form a concrete protective layer.

[0027] S32: Implement steel support treatment: Use steel pipes, angle steel components, or other steel components to provide arch support or horizontal bracing.

[0028] S33: Anchor bolt support treatment operation: Drill holes on the excavation surface, insert anchor bolts, and inject cement grout to fix them;

[0029] S34: Steel mesh support treatment operation: Cover the excavation surface with steel mesh to enhance the integrity of the structure and combine with the shotcrete protective layer;

[0030] Compared with the prior art, the embodiments of the present invention have at least the following technical advantages:

[0031] The method for constructing a horseshoe-shaped standard cross-section of a composite waterproof coating according to an embodiment of the present invention has at least the following technical advantages:

[0032] Firstly, advanced support methods are chosen, which involve injecting grout into the arch to reinforce the surrounding rock and improve its self-stabilizing ability. Simultaneously, this effectively controls large tunnel deformation under high ground stress conditions, reducing cavern deformation. In weak and fractured surrounding rock, advanced small-diameter pipe grouting support can improve the stability of the surrounding rock and reduce the risk of collapse.

[0033] Then, the upper half of the tunnel is excavated in a ring shape, leaving the core soil: by excavating in stages, disturbance to the surrounding rock is reduced, and the tunnel cross-section is gradually formed. The retention of the core soil helps to maintain the stability of the excavation face and prevents premature stress release from causing collapse.

[0034] Then comes the initial support of the upper section: the construction of initial support, such as shotcrete, anchor bolts, steel mesh, and steel frames, provides a temporary stable structure for the tunnel. The initial support of the upper section can effectively control the deformation of the surrounding rock and prevent problems such as cracking and spalling of the shotcrete in the initial support.

[0035] The lower section excavation then proceeds: excavation continues in the lower half of the tunnel to provide space for subsequent initial support and lining construction. Then, initial support for the lower section is implemented: this provides temporary stability to the lower section, preventing deformation and collapse of the surrounding rock.

[0036] Then comes the construction of the tunnel invert waterproofing layer and secondary lining: The construction of the invert helps to close into a stable support system, improving the bearing capacity of the tunnel bottom. The construction of the waterproofing layer can effectively prevent groundwater seepage and protect the tunnel structure from water damage. At the same time, the secondary lining, as a permanent structure, improves the durability and safety of the tunnel. Simultaneously, secondary lining construction is carried out at the tunnel arch wall at the top of the tunnel, and a composite waterproofing layer is installed between the tunnel arch wall and the top secondary lining; this composite waterproofing layer helps to improve the waterproofing effect of the lining and the overall tunnel. Attached Figure Description

[0037] Figure 1 This is an overall flowchart of a construction treatment method for a horseshoe-shaped standard cross-section of a composite waterproof coating provided in Embodiment 1 of the present invention;

[0038] Figure 2 This is a schematic diagram illustrating a specific step in the construction treatment method for a horseshoe-shaped standard cross-section of a composite waterproof coating provided in Embodiment 1 of the present invention;

[0039] Figure 3 This is a schematic diagram illustrating another specific step in the construction treatment method for a horseshoe-shaped standard cross-section of a composite waterproof coating provided in Embodiment 1 of the present invention.

[0040] Figure 4 This is a cross-sectional schematic diagram of a construction treatment method for a horseshoe-shaped standard cross-section of a composite waterproof coating provided in Embodiment 1 of the present invention.

[0041] Figure 5 This is a longitudinal cross-sectional schematic diagram of a horseshoe-shaped standard cross-section construction treatment method for a composite waterproof coating provided in Embodiment 1 of the present invention.

[0042] Labels: Small guide pipe 10; Upper half section 11; Lower half section 12; Initial support layer of upper half section 13; Initial support layer of lower half section 14; Waterproof layer of tunnel invert arch 15; Waterproof layer of tunnel arch wall 16; Core soil 17; Anchor bolt 18; Construction joint A. Detailed Implementation

[0043] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0044] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0045] See Figure 1Embodiment 1 of the present invention provides a method for constructing a horseshoe-shaped standard cross-section of a composite waterproof coating, comprising the following steps:

[0046] S1. Perform advanced support treatment on the arch surrounding rock: carry out grouting small pipe 10 construction treatment on the arch surrounding rock;

[0047] S2. Circular excavation of the upper section with core soil: Divide the excavation section into an upper section 11 and a lower section 12. In the order of top to bottom, first excavate the upper section 11 (then excavate the lower section 12 in step S4) and leave core soil 17.

[0048] S3. Initial support is provided on the upper half section 11 to form the initial support layer 13 of the upper half section, and the tunnel arch wall is constructed on this basis.

[0049] S4. Excavate the lower half of the cross section;

[0050] S5. Implement initial support on the lower half of the cross section to form the initial support layer 15 of the lower half of the cross section;

[0051] S6. At the bottom of the tunnel, above the initial support layer of the lower half section, install the tunnel invert waterproof layer 15 and carry out secondary lining construction.

[0052] S7. Secondary lining construction shall be carried out at the tunnel arch wall at the top of the tunnel, and a composite waterproof layer (i.e., tunnel arch wall waterproof layer 16) shall be installed between the tunnel arch wall and the secondary lining at the top.

[0053] Analysis of the main construction procedures of the horseshoe-shaped standard cross-section construction method for the above-mentioned composite waterproof coating reveals that: in step S1, advanced support is used to reinforce the surrounding rock by injecting grout into the arch, thereby improving its self-stabilizing ability. Simultaneously, it effectively controls large tunnel deformation under high ground stress conditions, reducing cavern deformation. In weak and fractured surrounding rock, advanced small-diameter pipe grouting support can improve the stability of the surrounding rock and reduce the risk of collapse.

[0054] Then, the upper half of the tunnel is excavated in a ring shape, leaving the core soil: by excavating in stages, disturbance to the surrounding rock is reduced, and the tunnel cross-section is gradually formed. The retention of the core soil helps to maintain the stability of the excavation face and prevents premature stress release from causing collapse.

[0055] Then comes the initial support of the upper section: the construction of initial support, such as shotcrete, anchor bolts, steel mesh, and steel frames, provides a temporary stable structure for the tunnel. The initial support of the upper section can effectively control the deformation of the surrounding rock and prevent problems such as cracking and spalling of the shotcrete in the initial support.

[0056] The lower section excavation then proceeds: excavation continues in the lower half of the tunnel to provide space for subsequent initial support and lining construction. Initial support for the lower section is implemented: similar to step S3 above, providing temporary stability to the lower section and preventing deformation and collapse of the surrounding rock.

[0057] During the execution of S6, the construction of the tunnel invert waterproofing layer and secondary lining is carried out: the construction of the invert helps to close into a stable support system, improving the bearing capacity of the tunnel bottom. The construction of the waterproofing layer effectively prevents groundwater seepage and protects the tunnel structure from water damage. At the same time, the secondary lining, as a permanent structure, improves the tunnel's durability and safety. During the execution of S7, secondary lining construction is carried out at the tunnel arch wall at the top of the tunnel, and a composite waterproofing layer is installed between the tunnel arch wall and the top secondary lining; this composite waterproofing layer helps to improve the waterproofing effect of the lining and the overall tunnel.

[0058] It needs to be explained that pre-support technology, specifically the use of small guide pipes, is a technique in tunnel construction primarily used for reinforcing weak and fractured rock strata. Pre-support small guide pipes are a highly effective auxiliary construction method for stabilizing the excavation face. During construction, the small guide pipes reinforce loose rock strata, and after grouting, they enhance the stability of loose and weak surrounding rock. This contributes to the stability of the surrounding rock after excavation and during the initial support period, preventing rock instability and eventual collapse.

[0059] The tunnel invert waterproofing layer, located at the bottom of the tunnel, is an important component of the tunnel structure. Its function is to form an integral part of the tunnel together with the secondary lining, increasing structural stability, and also providing waterproofing. The invert waterproofing layer is typically placed on top of the initial support at the tunnel bottom, below the secondary lining, and consists of a waterproof membrane (or waterproof liner) and a buffer layer; this structure is called a composite waterproofing layer.

[0060] The waterproofing layer for tunnel arch walls is typically installed in the arch wall section of the tunnel, located between the initial support and the secondary lining. This waterproofing layer consists of a waterproof membrane (or waterproof liner) and a buffer layer, forming a so-called composite waterproofing layer. The main function of the arch wall waterproofing layer is to prevent groundwater from seeping into the tunnel interior, protecting the tunnel structure from water damage. During construction, the waterproofing layer should be applied to the surface of the initial support. If there is significant seepage on the surface, drainage facilities should be added to prevent water accumulation due to recesses in the waterproofing layer, which could affect the construction of the secondary lining.

[0061] Preferably, as one possible implementation, the composite waterproof layer includes a waterproof membrane (or waterproof liner) and a buffer layer. The waterproof membrane is coated with a composite waterproof coating.

[0062] Preferably, as one possible implementation, the composite waterproof coating is a quick-setting rubber asphalt waterproof coating.

[0063] The aforementioned quick-setting rubber asphalt waterproof coating comprises two components: Agent A and Agent B. Agent A is a quick-setting liquid rubber waterproof and seepage-proof emulsion, composed of anionic rubber emulsion and emulsified asphalt. The rubber emulsion includes chloroprene latex, styrene-butadiene latex, or carboxylated styrene-butadiene latex, all of which are water-based spray materials. Agent B is a curing agent, a 5.0%–30.0% aqueous solution prepared from metal salt electrolytes. This spray-applied quick-setting rubber asphalt waterproof coating is the main waterproof coating in the previously filed patent application; its components have been disclosed and will not be repeated here.

[0064] See Figure 2 The construction operation of grouting small guide pipes for the surrounding rock of the arch includes the following steps:

[0065] S11. Conduct grouting tests;

[0066] S12. Perform drilling and small guide pipe installation operations;

[0067] S13. Perform grouting treatment;

[0068] S14. After grouting is completed, the holes are sealed to prevent grout backflow and ensure stable and long-lasting grouting effect.

[0069] It should be noted that the use of small-diameter grouting pipes is a common technique in tunnel or underground engineering, primarily used to reinforce weak or fractured surrounding rock, improve its stability, and prevent collapse. During the grouting process, if grout leaks from other holes (cross-flow), simultaneous grouting should be performed, or the leaking holes should be plugged promptly. After grouting is completed, the grouting effect should be checked; if it does not meet the requirements, additional grouting should be carried out.

[0070] Preferably, as one possible implementation, the grouting test includes: conducting a grouting test in a similar stratum outside the tunnel before formal grouting to determine whether the current grouting parameters are reasonable; if reasonable, continuing with subsequent operations.

[0071] The drilling and small guide pipe installation process is as follows: Before drilling, the hole position is measured and marked out. If the current hole position measuring instrument determines that the position is accurate, after drilling, high-pressure air or water is used to clean and blow away the sand, dust and accumulated water inside the hole.

[0072] The grouting process is as follows: before grouting, the working face is sealed with sprayed concrete to prevent grout leakage; the accumulated material inside the pipe is flushed out first, and then grouting is performed; the grouting sequence is from bottom to top, and the grout is mixed with a mixer.

[0073] It should be noted that: Grouting design requires the collection of data on soil properties, gradation, porosity, permeability coefficient, and moisture content before construction, taking into account environmental water sources, adjacent structures, and groundwater conditions. Based on this data, the grouting slurry (such as cement grout or chemical grout) is selected, the setting time is determined, and the grouting mix design is carried out. Simultaneously, grouting parameters such as pipe diameter, pipe length, pipe spacing, grouting pressure, grouting radius, and grouting volume are determined.

[0074] Grouting Test: Before formal grouting, a grouting test should be conducted in a similar stratum outside the tunnel to verify the appropriateness of the grouting equipment selection and configuration, and the rationality of the grouting parameters. The grouting test results should be carefully recorded, and the grouting entity should be excavated for verification to obtain data such as the actual grouting radius, soil consolidation time, and strength, which will serve as the basis for determining the grouting parameters.

[0075] Conduit processing: The conduit must be processed by a professional workshop on site. The grouting hole is drilled using a drilling machine, and a φ6 pipe clamp is welded to the tail end. It can only be used after passing the inspection by quality inspectors.

[0076] Drilling and installing guide pipes: Before drilling, the hole position must be measured and laid out using instruments to ensure accuracy. Drilling must be carried out according to the layout, and a directional frame must be used to control the drilling orientation so that the external insertion angle of the hole meets the design requirements. After drilling, the hole must be cleaned with high-pressure air and water to remove sand, dust, and accumulated water. All drilled holes must be inspected after completion, and any unqualified holes must be re-drilled.

[0077] Grouting: Before grouting, spray concrete to seal the working face to prevent grout leakage. For steel pipes that have been forcibly driven in, flush out any accumulated debris before grouting. Grouting should proceed from bottom to top. The grout can be mixed using a mixer or manually. Appropriate cementitious grout should be selected based on project requirements and mixed thoroughly. Grouting equipment should be calibrated regularly to ensure precise control of grouting pressure and volume. After grouting, seal the holes to prevent grout backflow and ensure stable and long-lasting grouting results.

[0078] See Figure 3 The implementation of initial support (the treatment process for initial support at the tunnel top or bottom is the same and will not be described again) includes:

[0079] S31: Shotcrete: Concrete is sprayed onto the excavated surface using a spraying device to form a concrete protective layer.

[0080] S32: Implement steel support treatment: Use steel pipes, angle steel components, or other steel components to provide arch support or horizontal bracing.

[0081] S33: Anchor bolt support treatment operation: Drill holes on the excavation surface, insert anchor bolts, and inject cement grout to fix them;

[0082] S34: Steel mesh support treatment operation: Cover the excavation face with steel mesh to enhance the integrity of the structure and combine with the shotcrete protective layer; the treatment process for the initial support of the tunnel top or bottom is the same as described above, and will not be repeated here.

[0083] It should be noted that step S31, shotcreting, involves applying concrete to the excavated surface using a spraying device to form a protective layer. The technical characteristics of these specific implementation steps are: rapid construction and effective enhancement of the excavated surface strength.

[0084] The above step S32 steel support: uses steel pipes, angle steel, or other steel components for support, usually set up in an arched or horizontal bracing manner. The technical characteristics of the above specific implementation steps: provides strength and stability, suitable for large excavation faces.

[0085] Step S33, anchor bolt support, involves drilling holes in the excavation face, inserting anchor bolts, and injecting cement grout for fixation. The technical characteristics of these specific implementation steps are: stabilizing the soil and rock mass and increasing the anti-sliding capacity of the excavation face.

[0086] Step S34: Steel mesh support. A steel mesh is placed over the excavation surface to enhance the overall structural integrity. Technical characteristics of this specific implementation step: It can be used in conjunction with shotcrete to improve the support effect. S35: Timber support can also be selectively applied: Timber is used as a support material, typically for small-scale excavations. Technical characteristics of this specific implementation step: Low cost, but limited load-bearing capacity, suitable for temporary support.

[0087] See Figure 4 and Figure 5 The above-mentioned method for constructing a horseshoe-shaped standard cross-section of a composite waterproof coating according to an embodiment of the present invention is illustrated in a construction site. Figure 4 The diagram illustrates the cross-sectional view of the construction process, however... Figure 5 This is a schematic diagram of the longitudinal section of the construction process.

[0088] Figure 4 The diagram illustrates the structure of the upper half section 11, the lower half section 12, the initial support layer of the upper half section 13, the initial support layer of the lower half section 14, the waterproof layer of the tunnel invert arch 15, the waterproof layer of the tunnel arch wall 16, as well as the core soil 17, the corner anchor bolt 18, and the construction joint A.

[0089] The invention provides a method for constructing a horseshoe-shaped standard cross-section of a composite waterproof coating. After implementation, the waterproof performance and structural stability are significantly improved.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art can modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for applying a composite waterproofing coating to a horseshoe-shaped standard section, characterized in that, The method comprises the following steps: S1, performing a pre-supporting treatment operation on the arch surrounding rock: performing a construction treatment operation of a grouting small pipe on the arch surrounding rock; S2, ring excavation of the upper half section with core soil: the excavation section is divided into the upper half section and the lower half section, and the upper half section is excavated first according to the sequence of upper first and lower second; S3, performing initial support on the upper half section to form an initial support layer of the upper half section, and then constructing a wall to form a tunnel arch wall; S4, excavating the lower half section; S5, performing initial support on the lower half section to form an initial support layer of the lower half section; S6, installing a tunnel inverted arch waterproof layer and performing secondary lining construction above the initial support layer of the lower half section at the bottom position of the tunnel; S7, performing secondary lining construction at the tunnel arch wall at the top position of the tunnel, and installing a composite waterproof layer between the tunnel arch wall and the secondary lining at the top.

2. The method of claim 1, wherein the composite waterproof coating is applied to the horse-shoe shaped standard section in a thickness of 0.5 to 1.5 mm. The composite waterproof layer comprises a waterproof plate and a buffer layer.

3. The method of claim 2, wherein the composite waterproof coating is applied to the horse-shoe shaped standard section in a thickness of 0.5 to 1.5 mm. The waterproof plate is coated with a composite waterproof coating.

4. The method of claim 3, wherein the composite waterproof coating is applied to the horse-shoe shaped standard section in a thickness of 0.5 to 1.5 mm. The composite waterproof coating is a rapid-setting rubber asphalt waterproof coating. The rapid-setting rubber asphalt waterproof coating comprises two components of A agent and B agent; the A agent component is a rapid-setting liquid rubber waterproof and anti-seepage material emulsion composed of an anionic rubber emulsion and emulsified asphalt; the rubber emulsion comprises chloroprene latex, styrene-butadiene latex or carboxyl styrene-butadiene latex, and is a water-based spraying material; the B agent component is a curing agent, which is a water solution with a concentration of 5.0%-30.0% prepared from a metal salt electrolyte.

5. The method of claim 1, wherein the composite waterproof coating is applied in a horse-shoe shaped standard cross-section. The construction treatment operation of the grouting small pipe on the arch surrounding rock comprises the following steps: S11, performing a grouting test; S12, performing a drilling and small pipe treatment operation; S13, performing a grouting treatment operation; S14, after grouting is completed, performing a hole sealing treatment to avoid backflow of the slurry.

6. The method of claim 5, wherein the composite waterproof coating is applied to the horse-shoe shaped standard section in a thickness of 0.5 to 1.5 mm. The grouting test comprises: before formal grouting, performing a grouting test on a similar stratum outside the hole to determine whether the current grouting parameters are reasonable; if they are reasonable, the subsequent operations are continued to be performed; The drilling and small pipe treatment operation: before drilling, hole position measurement and lofting are performed, and if the current hole position measurement instrument determines that the position is accurate; after drilling is completed, high-pressure air or water is used for cleaning to blow away the sand dust and accumulated water in the hole; The grouting treatment operation: before grouting, the masonry face is closed by spraying concrete to prevent slurry leakage; the accumulated material in the pipe is flushed first, and then grouting is performed; the grouting sequence is from bottom to top, and the slurry is stirred by a mixer.

7. The method of claim 6, wherein the composite waterproof coating is applied in a horse-shoe shaped standard cross-section. The initial support comprises: S31, spraying concrete: spraying concrete onto the excavation surface by a spraying device to form a layer of concrete protective layer; S32, performing a steel support treatment operation: supporting in an arch shape or using a steel pipe, angle steel structural member or the like to support in a cross bracing mode; S33, an anchor rod support treatment operation: drilling a hole in the excavation surface, inserting an anchor rod, and injecting cement slurry for fixation; S34, a steel mesh support treatment operation: covering a steel mesh on the excavation surface to enhance the integrity of the structure and combine with the sprayed concrete protective layer.

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