A classification grading reinforcement method for tunnel portal

Abstract

The application relates to the technical field of tunnel construction, in particular to a classification and grading reinforcement method for a tunnel portal, which comprises the following steps: step S1, acquiring field investigation data, and establishing a tunnel portal section topography and geology parameter model according to the field investigation data; step S2, grading tunnel portal deformation characteristics; step S3, grading tunnel portal deformation control levels; step S4, selecting a tunnel portal deformation treatment scheme according to the grading; step S5, combining different construction methods to formulate multiple alternative treatment schemes; and step S6, determining an optimal scheme based on multi-target optimization. The application has the advantages of strong applicability, high fine degree, high reliability, quantitative analysis and an engineering guiding significance of a comprehensive evaluation system.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, specifically to a method for classifying and reinforcing tunnel entrances. Background Technology

[0002] Currently, the design and construction of tunnel portal sections typically employ empirical and engineering analogy methods. However, there is a lack of understanding of the typical damage characteristics of tunnel portal sections and side / upper slopes under different topographical and geological conditions. Furthermore, there is a lack of evaluation criteria for the rationality of reinforcement measures adopted in design and construction. Consequently, in engineering practice, underestimation of project costs or overly conservative designs are prone to occur. Underestimation of engineering problems can easily lead to accidents such as collapses, surface cracking, and structural damage, while overly conservative designs can result in significantly increased project costs and unnecessary waste. These problems not only increase project costs but also affect tunnel construction safety and schedule. Therefore, how to scientifically and rationally select appropriate reinforcement and treatment measures is a pressing issue that needs to be addressed.

[0003] The technical problem to be solved by this invention is to provide a quantitative, refined, and engineering-guided method for classifying, grading, and optimizing tunnel portal reinforcement and treatment schemes. This method can accurately assess the deformation characteristics of tunnel portals for different types of tunnel portals, thereby balancing other limiting factors such as engineering investment, engineering safety, environment, and ecology, and realizing the evaluation of tunnel portal deformation control schemes, providing a scientific basis for the final determination of tunnel portal reinforcement and treatment schemes. Summary of the Invention

[0004] The purpose of this invention is to provide a method for classifying and reinforcing tunnel entrances to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for classifying and grading reinforcement of tunnel entrances, wherein the method includes the following steps:

[0007] Step S1: Establishment of topographic and geological parameter model:

[0008] Obtain on-site survey data and establish a topographic and geological parameter model of the tunnel entrance section based on the on-site survey data;

[0009] Step S2: Classify the deformation characteristics of the tunnel entrance:

[0010] Based on the established topographic and geological parameter model of the tunnel portal section, and according to the surrounding rock grade, slope gradient, and burial depth, the degree of deformation characteristics of the tunnel portal is divided into four levels from high to low: Level 1, Level 2, Level 3, and Level 4.

[0011] Step S3: Classify the deformation control level at the tunnel entrance:

[0012] Based on the tunnel safety level and the degree of deformation characteristics at the tunnel entrance, the tunnel entrance deformation control level is classified into four levels from high to low: Level 1, Level 2, Level 3 and Level 4.

[0013] Step S4: Select a treatment plan for tunnel portal deformation based on the classification:

[0014] Based on the classification of tunnel portal deformation control level, a tunnel portal deformation reinforcement treatment scheme is selected. The treatment scheme for Level 1 is surface pre-reinforcement and surrounding rock pre-reinforcement, the treatment scheme for Level 2 is surface pre-reinforcement, the treatment scheme for Level 3 is surrounding rock pre-reinforcement, and the treatment scheme for Level 4 is no reinforcement required.

[0015] Step S5: Combining different construction methods, formulate multiple alternative treatment plans:

[0016] Based on the tunnel portal deformation reinforcement treatment scheme, the advantages and disadvantages of different construction techniques and methods are analyzed, and a suitable treatment method is selected for the tunnel portal deformation reinforcement treatment method, and alternative tunnel portal deformation reinforcement treatment schemes are determined.

[0017] Step S6: Determine the optimal solution based on multi-objective optimization:

[0018] By combining various limiting factors, a multi-objective optimization analysis was conducted to complete the optimization analysis of the alternative tunnel portal deformation reinforcement treatment schemes, and a recommended scheme that meets the selection criteria was obtained.

[0019] Furthermore, in step S2:

[0020] When it is determined that the surrounding rock grade has increased, it is confirmed that the integrity and self-stabilizing ability of the surrounding rock have decreased.

[0021] When it is determined that the slope of the side slope increases, it is confirmed that the corresponding burial depth also increases;

[0022] When it is determined that the burial depth is increasing, it is confirmed that the impact on the deformation of the tunnel entrance is decreasing.

[0023] Furthermore, in step S3, the tunnel safety level is divided into five levels: I, II, III, IV, and V, corresponding to five levels: excellent, good, medium, poor, and very poor.

[0024] Furthermore, in step S4:

[0025] Surface pre-reinforcement involves reinforcing the slope at the tunnel entrance to protect its stability.

[0026] Pre-reinforcement of the surrounding rock involves grouting, driving steel pipes, steel plates, and anchor bolts into the strata in front of the tunnel face before tunnel excavation. This forms an arched continuous body on the tunnel cross section, which reinforces the strata in front of the excavation and maintains the stability of the soil in front by utilizing the supporting force of the arched continuous body, thereby reducing the amount of surface settlement.

[0027] Furthermore, in step S5:

[0028] The criteria for evaluating the quality of construction techniques and methods include actual applicability to construction, construction period, reinforcement effect, project cost, and safety and environmental protection.

[0029] Surface pre-reinforcement uses surface grouting, ground anchors, high-pressure shotcrete, retaining walls, anti-slide piles, and anchor cables; surrounding rock pre-reinforcement uses advanced anchors, advanced small guide pipes, and advanced pipe roofs.

[0030] Among them, when the grouting method is adopted, the reinforcement is carried out by the grouting device (1).

[0031] Furthermore, in step S6:

[0032] The limiting factors include engineering economics, structural durability, project importance, ease of construction, and ecological balance.

[0033] Furthermore, the grouting device includes a base plate, on which a mixing shell and a high-pressure pump are fixedly installed on both sides of the upper surface of the base plate, respectively. The interior of the mixing shell is divided into a mixing chamber and an installation chamber by a horizontal plate. The top of the mixing shell is integrally provided with a feeding port. A mixing drum is welded into the mixing chamber. The top opening of the mixing drum is located below the feeding port. A vertical mixing rod is rotatably provided on the inner bottom plate of the mixing drum, and an annular scraper is provided on the inner wall of the mixing drum near the opening. The outer wall of the scraper is in contact with the inner wall of the mixing drum. Both sides of the mixing shell are provided with driving components connected to the upper sides of the scraper to facilitate vertical movement of the scraper to clean the inner wall of the mixing drum. A discharge pipe is provided on one side of the inner bottom plate of the mixing drum. The discharge pipe is located in the installation chamber and passes through the shell wall of the mixing shell and is connected to the input port of the high-pressure pump. The output port of the high-pressure pump is connected to a conveying hose, and a solenoid valve is installed on the discharge pipe.

[0034] Furthermore, the drive assembly includes protective shells disposed on both sides of the stirring shell. Drive motors are bolted inside the two protective shells. The output ends of the two drive motors extend through the top of the protective shells and are connected to lead screws via couplings. Sleeves are fitted on the top of the two lead screws. Connecting plates are connected to the top of the two sleeves. Vertical connecting rods are connected to the lower surface of the two connecting plates on the side away from the sleeves. The bottom ends of the two connecting rods pass through the top plate of the stirring shell and are welded and fixed to both sides of the upper surface of the scraper.

[0035] Furthermore, the two protective shells are welded and fixed to the side wall of the stirring shell and the upper surface of the bottom plate, respectively. The bottom outer wall of the two sleeves is provided with annular grooves along the circumference. Annular plates are fixedly fitted in the two annular grooves. Movable plates are welded to the side of the two annular plates near the stirring shell. Vertical movable grooves are provided on both sides of the stirring shell. The ends of the two movable plates away from the annular plates are inserted into the movable grooves, and the outer wall of the movable plate is in contact with the inner wall of the movable groove and is in a sliding connection.

[0036] Furthermore, a baffle is horizontally provided inside the feeding port, and a rotating shaft is welded to both sides of the baffle. One of the rotating shafts is movably connected to the inner wall of the feeding port, and a control motor is bolted to the outer wall of the feeding port. The output end of the control motor passes through the side wall of the feeding port and is connected to the other rotating shaft through a coupling.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] (1) Strong applicability and high degree of refinement. This invention classifies the degree of deformation characteristics of different tunnel entrances, grades the level of deformation control of tunnel entrances, and further evaluates the advantages and disadvantages of different tunnel entrance deformation reinforcement treatment schemes for different construction methods and other limiting factors. Under the premise of ensuring the control effect, it finds the better treatment scheme and can be applied to the reinforcement treatment of tunnel entrance deformation under various engineering conditions.

[0039] (2) High reliability and quantitative analysis. This invention adopts a hierarchical model and supplements it with correction factors to reasonably adjust the evaluation level. It has high reliability and can analyze the deformation of tunnel entrances under different background conditions, so as to more accurately and reasonably evaluate the deformation control level of tunnel entrances.

[0040] (3) The comprehensive evaluation system has engineering guidance significance. Based on the precise model, this invention conducts multi-objective optimization analysis on engineering economic and other limiting factors, and evaluates each alternative control scheme by quantitative comparison, so as to obtain the optimal scheme under the specified requirements. It balances the relationship between various engineering considerations, takes into account economy, safety and feasibility, and has extremely high guiding significance for the selection of tunnel portal reinforcement and treatment schemes. Attached Figure Description

[0041] Figure 1 This is a flowchart of the present invention;

[0042] Figure 2 This is a schematic diagram of the grouting device in this invention;

[0043] Figure 3 This is a cross-sectional view of the stirring shell in this invention;

[0044] Figure 4 This is a schematic diagram of the baffle structure in this invention;

[0045] Figure 5 This is a schematic diagram of the annular plate in this invention;

[0046] Figure 6 This is a schematic diagram of the annular groove in the present invention;

[0047] Figure 7 This is a schematic diagram of the scraper structure in this invention.

[0048] In the diagram: 1. Grouting device; 101. Base plate; 2. Mixing shell; 201. Horizontal plate; 202. Mixing chamber; 203. Mounting chamber; 204. Control panel; 205. Feed port; 3. Mixing tank; 301. Mixing rod; 302. Scraper; 303. Discharge pipe; 3031. Solenoid valve; 4. Baffle; 401. Rotating shaft; 402. Control motor; 5. Drive assembly; 501. Protective shell; 502. Drive motor; 503. Lead screw; 504. Sleeve; 505. Connecting plate; 506. Connecting rod; 6. Annular groove; 601. Moving plate; 602. Annular plate; 603. Moving groove; 7. High-pressure pump; 701. Material conveying hose. Detailed Implementation

[0049] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0050] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are shown. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0051] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0053] Please see Figures 1 to 7 This invention provides a method for classifying and grading reinforcement of tunnel entrances, comprising the following steps:

[0054] Step S1: Establishment of topographic and geological parameter model:

[0055] Obtain on-site survey data and establish a topographic and geological parameter model of the tunnel entrance section based on the on-site survey data;

[0056] Step S2: Classify the deformation characteristics of the tunnel entrance:

[0057] Based on the established topographic and geological parameter model of the tunnel portal section, and according to factors such as surrounding rock grade, side slope gradient, burial depth, and other special conditions, the degree of deformation characteristics at the tunnel portal is divided into four levels from high to low: Level 1, Level 2, Level 3, and Level 4, as shown in Table 1.

[0058] Table 1 Classification of Deformation Characteristics at Tunnel Entrances

[0059]

[0060] In step S2:

[0061] The higher the grade of the surrounding rock, the worse its integrity and self-stabilizing ability, and the greater its impact on the deformation of the tunnel entrance.

[0062] The steeper the slope of the side slope, the greater the impact on the deformation of the tunnel entrance should be. However, considering that the steeper the slope of the side slope, the greater the corresponding burial depth, the impact on the deformation of the tunnel entrance will be reduced accordingly.

[0063] The greater the burial depth, the smaller the impact on the deformation of the tunnel entrance; depths exceeding 20m have almost no effect on the deformation of the tunnel entrance.

[0064] Other special circumstances refer to adverse geological conditions such as loess strata, expansive soil strata, rock bursts, faults, karst caves, water inrush, landslides, loose strata, high-temperature strata, gas strata, and tunnel bias pressure, which directly classify the degree of deformation at the tunnel entrance as Level 1.

[0065] Step S3: Classify the deformation control level at the tunnel entrance:

[0066] Based on the tunnel safety level and the degree of deformation characteristics at the tunnel portal, the tunnel portal deformation control level is classified into four levels from high to low: Level 1, Level 2, Level 3, and Level 4, as shown in Table 2.

[0067] Table 2 Deformation Control Levels at Tunnel Portals

[0068]

[0069] In step S3, the tunnel safety level is divided into five levels according to the "Research on Safety Level Evaluation of Highway Tunnels" table: I, II, III, IV, and V, corresponding to excellent, good, medium, poor, and very poor, respectively.

[0070] Step S4: Select a treatment plan for tunnel portal deformation based on the classification:

[0071] Based on the classification of tunnel portal deformation control levels, the tunnel portal deformation reinforcement treatment schemes are selected, as shown in Table 3:

[0072] Table 3 Methods for Strengthening and Treating Deformation at Tunnel Entrances

[0073]

[0074] In step S4:

[0075] Surface pre-reinforcement is the reinforcement of the slope at the tunnel entrance to protect its stability; surrounding rock pre-reinforcement refers to the technical measures such as grouting, driving steel pipes, steel plates, and anchor bolts into the strata in front of the tunnel face before tunnel excavation, thereby forming an arched continuous body on the tunnel cross section, which not only reinforces the strata in front of the excavation, but also uses its supporting force to maintain the stability of the soil in front, reducing the amount of surface settlement.

[0076] Step S5: Combining different construction methods, formulate multiple alternative treatment plans:

[0077] Based on the tunnel portal deformation reinforcement treatment scheme, the advantages and disadvantages of different construction techniques and methods are analyzed, and a suitable treatment method is selected for the tunnel portal deformation reinforcement treatment method, and alternative tunnel portal deformation reinforcement treatment schemes are determined.

[0078] In step S5, the evaluation criteria for the quality of construction technology and methods include actual construction applicability, construction period, reinforcement effect, project cost, and safety and environmental protection.

[0079] Surface pre-reinforcement mainly employs surface grouting, ground anchor bolts, high-pressure shotcrete, retaining walls, anti-slide piles, and anchor cables. Surrounding rock pre-reinforcement mainly employs advanced anchor bolts, advanced small guide pipes, and advanced pipe roofs. When using grouting methods, reinforcement is carried out through grouting device 1.

[0080] Step S6: Determine the optimal solution based on multi-objective optimization:

[0081] By combining various limiting factors, a multi-objective optimization analysis was conducted to complete the optimization analysis of the alternative tunnel portal deformation reinforcement treatment schemes, and a recommended scheme that meets the selection criteria and the selection opinion were obtained.

[0082] In step S6, the limiting factors include engineering economics, structural durability, engineering importance, ease of construction, and ecological balance factors.

[0083] Please see Figures 2 to 7 The grouting device 1 includes a base plate 101. A mixing shell 2 and a high-pressure pump 7 are fixedly installed on both sides of the upper surface of the base plate 101. The interior of the mixing shell 2 is divided into a mixing chamber 202 and an installation chamber 203 by a horizontal plate 201. The top of the mixing shell 2 is integrally provided with a feeding port 205. A mixing tank 3 is welded in the mixing chamber 202. The top opening of the mixing tank 3 is located below the feeding port 205. A vertical mixing rod 301 is rotatably provided on the inner bottom plate of the mixing tank 3. The bottom end of the mixing rod 301 passes through the floor of the mixing tank 3 and the horizontal plate 201 in sequence and is connected to a mixing motor through a coupling.

[0084] The stirring motor is bolted to the bottom plate of the mounting cavity 203, and the inner wall of the mixing tank 3 is provided with an annular scraper 302 near the opening. The outer wall of the scraper 302 is in contact with the inner wall of the mixing tank 3. Both sides of the mixing shell 2 are provided with drive components 5 connected to the upper surface of the scraper 302 to facilitate the vertical movement of the scraper 302 to clean the inner wall of the mixing tank 3. A discharge pipe 303 is opened on one side of the inner bottom plate of the mixing tank 3. The discharge pipe 303 is located in the mounting cavity 203 and passes through the shell wall of the mixing shell 2 to be connected to the input port of the high pressure pump 7.

[0085] The output port of the high-pressure pump 7 is connected to a material conveying hose 701, and a solenoid valve 3031 is installed on the discharge pipe 303. The inside of the feeding port 205 is horizontally provided with a baffle 4. Both sides of the baffle 4 are welded with rotating shafts 401. One rotating shaft 401 is movably connected to the inner wall of the feeding port 205. A control motor 402 is bolted to the outer wall of the feeding port 205. The output end of the control motor 402 passes through the side wall of the feeding port 205 and is connected to the other rotating shaft 401 through a coupling.

[0086] When using grouting for reinforcement, the workers move the device to the designated position using the four corner wheels at the bottom of the base plate 101. Then, they start the control motor 402 and the stirring motor through the control panel on the outer wall of the mixing shell 2. The control motor 402 rotates the connected rotating shaft 401 through the rotating output shaft. The rotating shaft 401 drives the baffle 4 to rotate until the horizontal baffle 4 is in a vertical position. At this time, the control motor 402 stops working. The workers then feed the raw materials into the mixing tank 3 through the open feeding port 205. At the same time, the stirring motor drives the stirring rod 301 to rotate and stir the incoming raw materials.

[0087] After a certain amount of raw materials are added, the operator starts the control motor 402 via the control panel 204 to rotate the vertical baffle 4 back to the horizontal state, which closes the feeding port 205, thus controlling the addition of raw materials. After mixing is completed, the control panel 204 opens the solenoid valve 3031 and the high-pressure pump 7. Under the action of the high-pressure pump 7, the mixed slurry enters the high-pressure pump 7 through the discharge pipe 303 and completes the slurry injection operation through the conveying hose 701. When it is necessary to clean the inner wall of the mixing tank 3, the drive component 5 can be started via the control panel 204 to drive the scraper 302 to move vertically along the inner wall of the mixing tank 3 to scrape off the slurry adhering to the inner wall, thereby reducing slurry waste and preventing the slurry from solidifying on the inner wall of the mixing tank 3. The operation is simple and convenient.

[0088] Please see Figure 2 , Figure 3 , Figure 5 , Figure 6 and Figure 7 The drive assembly 5 includes protective shells 501 disposed on both sides of the stirring shell 2. Drive motors 502 are bolted inside the two protective shells 501. The output ends of the two drive motors 502 pass through the top of the protective shells 501 and are connected to lead screws 503 through a coupling. Sleeves 504 are sleeved on the top of the two lead screws 503.

[0089] The inner wall of the sleeve 504 is threadedly engaged with the outer wall of the lead screw 503. The top ends of the two sleeves 504 are connected to the connecting plates 505. The lower surfaces of the two connecting plates 505 away from the sleeves 504 are each connected to a vertical connecting rod 506. The bottom ends of the two connecting rods 506 pass through the top plate of the mixing shell 2 and are welded and fixed to both sides of the upper surface of the scraper 302. The two protective shells 501 are respectively welded and fixed to the side wall of the mixing shell 2 and the upper surface of the bottom plate 101. The bottom outer wall of the two sleeves 504 is provided with an annular groove 6 along the circumference. An annular plate 602 is fixedly fitted in the two annular grooves 6. The side of the two annular plates 602 close to the mixing shell 2 is welded with a movable plate 601. Vertical movable grooves 603 are provided on both sides of the mixing shell 2. The ends of the two movable plates 601 away from the annular plates 602 are inserted into the movable grooves 603, and the outer wall of the movable plate 601 is in contact with the inner wall of the movable groove 603 and is in a sliding connection.

[0090] When cleaning the inner wall of the mixing tank 3, the operator starts the drive motor 502 in the drive assembly 5 through the control panel 204. The drive motor 502 drives the lead screw 503 to rotate. The sleeve 504, which is threadedly connected to the lead screw 503, moves vertically following the rotation of the lead screw 503 under the action of the moving plate 601 and the moving groove 603. The vertically moving sleeve 504 drives the connecting plate 505 to move. The connecting plate 505 drives the scraper 302 to move vertically through the connecting rod 506, thereby completing the cleaning of the inner wall of the mixing tank 3, reducing the waste of slurry, and preventing the slurry from solidifying on the inner wall of the mixing tank 3.

[0091] Operating principle of grouting device 1:

[0092] The operator starts the drive motor 502 in the drive assembly 5 through the control panel 204. The drive motor 502 drives the lead screw 503 to rotate. The sleeve 504, which is threadedly connected to the lead screw 503, moves vertically following the rotation of the lead screw 503 under the action of the moving plate 601 and the moving groove 603. The vertically moving sleeve 504 drives the connecting plate 505 to move. The connecting plate 505 drives the scraper 302 to move vertically through the connecting rod 506. The outer wall of the moving scraper 302 scrapes off the slurry adhering to the inner wall of the mixing tank 3.

[0093] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for classifying and grading reinforcement of tunnel entrances, characterized in that, The method includes the following steps: Step S1: Establishment of topographic and geological parameter model: Obtain on-site survey data and establish a topographic and geological parameter model of the tunnel entrance section based on the on-site survey data; Step S2: Classify the deformation characteristics of the tunnel entrance: Based on the established topographic and geological parameter model of the tunnel portal section, and according to the surrounding rock grade, slope gradient, and burial depth, the degree of deformation characteristics of the tunnel portal is divided into four levels from high to low: Level 1, Level 2, Level 3, and Level 4. Step S3: Classify the deformation control level at the tunnel entrance: Based on the tunnel safety level and the degree of deformation characteristics at the tunnel entrance, the tunnel entrance deformation control level is classified into four levels from high to low: Level 1, Level 2, Level 3 and Level 4. Step S4: Select a treatment plan for tunnel portal deformation based on the classification: Based on the classification of tunnel portal deformation control level, a tunnel portal deformation reinforcement treatment scheme is selected. The treatment scheme for Level 1 is surface pre-reinforcement and surrounding rock pre-reinforcement, the treatment scheme for Level 2 is surface pre-reinforcement, the treatment scheme for Level 3 is surrounding rock pre-reinforcement, and the treatment scheme for Level 4 is no reinforcement required. Step S5: Combining different construction methods, formulate multiple alternative treatment plans: Based on the tunnel portal deformation reinforcement treatment scheme, the advantages and disadvantages of different construction techniques and methods are analyzed, and a suitable treatment method is selected for the tunnel portal deformation reinforcement treatment method, and alternative tunnel portal deformation reinforcement treatment schemes are determined. Step S6: Determine the optimal solution based on multi-objective optimization: By combining various limiting factors, a multi-objective optimization analysis was conducted to complete the optimization analysis of the alternative tunnel portal deformation reinforcement treatment schemes, and a recommended scheme that meets the selection criteria was obtained.

2. The method for classifying and reinforcing tunnel entrances according to claim 1, characterized in that: In step S2: When it is determined that the surrounding rock grade has increased, it is confirmed that the integrity and self-stabilizing ability of the surrounding rock have decreased. When it is determined that the slope of the side slope increases, it is confirmed that the corresponding burial depth also increases; When it is determined that the burial depth is increasing, it is confirmed that the impact on the deformation of the tunnel entrance is decreasing.

3. The method for classifying and grading reinforcement of tunnel entrances according to claim 1, characterized in that: In step S3, the tunnel safety level is divided into five levels: I, II, III, IV, and V, corresponding to five levels: excellent, good, medium, poor, and very poor.

4. The method for classifying and reinforcing tunnel entrances according to claim 1, characterized in that: In step S4: Surface pre-reinforcement involves reinforcing the slope at the tunnel entrance to protect its stability. Pre-reinforcement of the surrounding rock involves grouting, driving steel pipes, steel plates, and anchor bolts into the strata in front of the tunnel face before tunnel excavation. This forms an arched continuous body on the tunnel cross section, which reinforces the strata in front of the excavation and maintains the stability of the soil in front by utilizing the supporting force of the arched continuous body, thereby reducing the amount of surface settlement.

5. A method for classifying and grading reinforcement of tunnel entrances according to claim 1, characterized in that: In step S4: The criteria for evaluating the quality of construction techniques and methods include actual applicability to construction, construction period, reinforcement effect, project cost, and safety and environmental protection. Surface pre-reinforcement uses surface grouting, ground anchors, high-pressure shotcrete, retaining walls, anti-slide piles, and anchor cables; surrounding rock pre-reinforcement uses advanced anchors, advanced small guide pipes, and advanced pipe roofs. Among them, when the grouting method is adopted, the reinforcement is carried out by the grouting device (1).

6. The method for classifying and reinforcing tunnel entrances according to claim 1, characterized in that: In step S6: The limiting factors include engineering economics, structural durability, project importance, ease of construction, and ecological balance.

7. A method for classifying and reinforcing tunnel entrances according to claim 5, characterized in that: The grouting device (1) includes a base plate (101). A mixing shell (2) and a high-pressure pump (7) are fixedly installed on both sides of the upper surface of the base plate (101). The interior of the mixing shell (2) is divided into a mixing chamber (202) and an installation chamber (203) by a horizontal plate (201). The top of the mixing shell (2) is integrally provided with a feeding port (205). A mixing barrel (3) is welded in the mixing chamber (202). The top opening of the mixing barrel (3) is located below the feeding port (205). A vertical stirring rod (301) is rotatably provided on the inner bottom plate of the mixing barrel (3), and an annular scraper is provided on the inner wall of the mixing barrel (3) near the opening. The outer wall of the scraper (302) is in contact with the inner wall of the mixing tank (3). Both sides of the mixing shell (2) are provided with drive components (5) connected to the upper surface of the scraper (302) to facilitate the vertical movement of the scraper (302) to clean the inner wall of the mixing tank (3). A discharge pipe (303) is provided on one side of the inner bottom plate of the mixing tank (3). The discharge pipe (303) is located in the mounting cavity (203) and passes through the shell wall of the mixing shell (2) to be connected to the input port of the high pressure pump (7). The output port of the high pressure pump (7) is connected to a conveying hose (701), and a solenoid valve (3031) is installed on the discharge pipe (303).

8. A method for classifying and grading reinforcement of tunnel entrances according to claim 7, characterized in that: The drive assembly (5) includes protective shells (501) disposed on both sides of the stirring shell (2). Drive motors (502) are bolted inside the two protective shells (501). The output ends of the two drive motors (502) pass through the top of the protective shells (501) and are connected to lead screws (503) via couplings. Sleeves (504) are sleeved on the top of the two lead screws (503). Connecting plates (505) are connected to the top of the two sleeves (504). Vertical connecting rods (506) are connected to the lower surface of the two connecting plates (505) on the side away from the sleeves (504). The bottom ends of the two connecting rods (506) pass through the top plate of the stirring shell (2) and are welded and fixed to both sides of the upper surface of the scraper (302).

9. A method for classifying and grading reinforcement of tunnel entrances according to claim 8, characterized in that: The two protective shells (501) are welded and fixed to the side wall of the stirring shell (2) and the upper surface of the bottom plate (101), respectively. The bottom outer wall of the two sleeves (504) is provided with an annular groove (6) along the circumference. An annular plate (602) is fixedly fitted in each of the two annular grooves (6). A movable plate (601) is welded to the side of the two annular plates (602) near the stirring shell (2). Vertical movable grooves (603) are provided on both sides of the stirring shell (2). The ends of the two movable plates (601) away from the annular plates (602) are inserted into the movable grooves (603), and the outer wall of the movable plate (601) is in contact with the inner wall of the movable groove (603) and is in a sliding connection.

10. A method for classifying and grading reinforcement of tunnel entrances according to claim 7, characterized in that: The feed port (205) is provided with a horizontal baffle (4) inside. A rotating shaft (401) is welded on both sides of the baffle (4). One of the rotating shafts (401) is movably connected to the inner wall of the feed port (205). A control motor (402) is bolted to the outer wall of the feed port (205). The output end of the control motor (402) passes through the side wall of the feed port (205) and is connected to the other rotating shaft (401) through a coupling.

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