Tunnel advance small catheter and its grouting method

Abstract

The application provides a tunnel advanced small catheter and a grouting method thereof, which comprises an advanced small catheter body, a grouting pipe arranged in the inside of the advanced small catheter body, the outer diameter of the grouting pipe is smaller than the inner diameter of the advanced small catheter body, a piston is detachably installed on the front end of the grouting pipe, the piston is sealed and blocked in the inside of the advanced small catheter body, a plurality of grouting holes are arranged on the front end of the piston, the grouting holes are communicated with the grouting pipe, a check valve is arranged in the inside of the piston for controlling the opening and closing of the grouting holes, a limiting device for preventing the piston from being taken out is arranged on the inner wall of the rear end of the advanced small catheter body, and the grouting pipe can pass out of the limiting device. The grouting uniformity is good, the slurry can be gradually and uniformly filled from the hole bottom to the hole opening during grouting, the problem of local grouting insufficiency in the traditional grouting method is avoided, the reinforcement effect of the surrounding rock is effectively improved, and the stability and safety of the tunnel are enhanced.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a tunnel pre-grouting guide pipe and its grouting method. Background Technology

[0002] In tunnel construction, pre-support is one of the key measures to ensure the safety and stability of tunnel excavation. Pre-support grouting with small steel pipes, as an effective method, involves driving small steel pipes into the surrounding rock diagonally above or near the arch of the tunnel face before excavation and then grouting to improve the surrounding rock condition and ensure the stability of the tunnel face. However, existing pre-support grouting pipes and their grouting methods still have some shortcomings in practical applications, such as unstable grouting effects and slow construction progress.

[0003] For example, the traditional grouting process using pre-drilled small guide pipes in tunnels involves installing a grouting pipe at the tail of the guide pipe, allowing the grout to flow from the pipe opening to the bottom of the hole. This presents the following technical challenges: 1. Poor grouting uniformity: The diffusion of grout in the surrounding rock is often uneven, potentially resulting in some areas being fully grouted while others are under-grouted. This leads to inconsistent reinforcement effects, affecting the overall stability of the surrounding rock and failing to fully utilize the support function of the pre-drilled small guide pipe, thus increasing safety risks during tunnel construction. 2. Inaccurate grouting pressure control: It is difficult to precisely control the grouting pressure. If the grouting pressure is too low, the grout cannot effectively penetrate into the fissures of the surrounding rock, failing to achieve the expected reinforcement effect. If the grouting pressure is too high, it may cause splitting and damage to the surrounding rock, not only destroying the original structure of the surrounding rock but also potentially leading to surface heave, tunnel lining deformation, and other problems, seriously affecting the quality of tunnel construction and the safety of the surrounding environment. 3. Slow grouting speed: Traditional grouting techniques have a relatively slow grouting speed, which prolongs the construction time of a single grouting hole, thereby increasing the overall construction cycle of tunnel pre-support. This is detrimental to the efficient progress of tunnel engineering, potentially leading to delays and increased project costs, including equipment rental, labor costs, and management costs. 4. Significant grout waste: Due to uneven grouting and inaccurate pressure control, grout is often over-injected or injected into areas that do not require reinforcement, resulting in significant grout waste and increased construction material costs. Furthermore, improper disposal of waste grout can cause environmental pollution, such as contaminating groundwater and soil. 5. Poor adaptability to complex geological conditions: When encountering complex and variable geological conditions, such as fractured zones, water-rich strata, and weak surrounding rock, traditional grouting techniques struggle to adjust grouting parameters and methods promptly and effectively according to geological conditions. This leads to unsatisfactory grouting results and may even result in grouting failure, posing significant difficulties and safety hazards to tunnel construction. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention aims to provide a tunnel pre-support small guide pipe and its grouting method, so as to achieve uniform and efficient grouting of pre-support, improve the safety of tunnel construction, and ensure the construction progress and quality of pre-support.

[0005] To achieve the above objectives, the present invention proposes a tunnel pre-conduit pipe, comprising a pre-conduit pipe body and a grouting pipe. The grouting pipe is disposed inside the pre-conduit pipe body, and its outer diameter is smaller than the inner diameter of the pre-conduit pipe body. A piston is detachably installed at the front end of the grouting pipe. The piston is sealed inside the pre-conduit pipe body. The front end of the piston is provided with several grouting holes, which communicate with the grouting pipe. A check valve for controlling the opening and closing of each grouting hole is provided inside the piston. A limiting device for preventing the piston from falling out is provided on the inner wall of the rear end of the pre-conduit pipe body, and the grouting pipe can pass through the limiting device.

[0006] In the above scheme: the piston is provided with a grouting port for inserting a grouting pipe, and the grouting port connects the grouting pipe to each grouting hole. Specifically, the grouting port is located at the rear end of the piston, and the grouting pipe is inserted into the grouting port and connects to each grouting hole.

[0007] In the above scheme: the check valve is a spring-loaded check valve, which is located at the connection between the grouting port and the piston. The grouting pressure controls the automatic opening or closing of the spring-loaded check valve. After grouting is completed, the grouting pipe is removed, and the spring-loaded check valve automatically closes the grouting port to prevent grout backflow.

[0008] In the above scheme: the piston is conical, and the grouting hole is located on the conical surface and tip of the piston. The piston can be made of an elastic material, such as rubber, which has a certain degree of flexibility and sealing performance, and can withstand a certain grouting pressure without being damaged.

[0009] In the above scheme, the piston and the grouting pipe are connected by a threaded connection, which makes disassembly convenient.

[0010] In the above scheme: the limiting device is in the shape of a cone frustum, the inner diameter of the limiting device is larger than the outer diameter of the grouting pipe, the limiting device is used to stop the piston to prevent it from falling out, and will not interfere with the passage of the grouting pipe.

[0011] This invention also proposes a grouting method for tunnel pre-conduit pipes. Based on the aforementioned tunnel pre-conduit pipes, the grouting method includes the following steps:

[0012] S1. Determine the installation position and angle of the advance guide pipe at the tunnel face, and use drilling equipment to drill holes at the predetermined positions;

[0013] S2. Insert the pre-drilled guide pipe into the borehole, ensuring that the front end of the pre-drilled guide pipe reaches the design depth and is in close contact with the surrounding rock. At the same time, install a grout stop plug at the pipe opening to seal the gap between the borehole wall and the pre-drilled guide pipe.

[0014] S3. Connect the rear end of the grouting pipe to the grouting equipment and extend the front end of the grouting pipe into the front end of the advanced small guide tube body to ensure that the grout can be injected from the bottom of the borehole.

[0015] S4. Start the grouting equipment. The grout is injected into the gap between the pre-drilled guide pipe and the surrounding rock through the grouting pipe. As the grouting pressure increases, the piston is pushed by the grout and moves the grouting pipe toward the borehole opening. During the movement, the grout continuously fills the gap, achieving uniform grouting.

[0016] S5. When the piston moves to the position of the limit device, stop grouting, remove the grouting pipe, and close the check valve.

[0017] In the above scheme: after the grouting pipe is removed, it is cleaned and inspected, and then used for the grouting operation of the next advanced small guide pipe body. That is, the grouting pipe can be recycled, which helps to save costs.

[0018] The beneficial effects of this invention are:

[0019] 1. Good grouting uniformity: Through the movement of the grouting pipe and piston during the grouting process, the grout can be evenly filled from the bottom of the hole to the opening, avoiding the problem of local incomplete grouting that occurs in traditional grouting methods, effectively improving the reinforcement effect of the surrounding rock, and enhancing the stability and safety of the tunnel.

[0020] 2. High grouting efficiency: Due to the uniform and rapid grouting, the grouting time of a single advanced small guide pipe is greatly shortened compared with traditional grouting technology, thereby improving the construction efficiency of the entire tunnel advanced support, helping to speed up the tunnel construction progress and reduce construction costs.

[0021] 3. Easy to operate: It does not require complicated equipment and processes, is easy to promote and use, and construction personnel can master the technology after simple training. The technical difficulty is low, and it effectively reduces human error in the construction process, improving construction quality and reliability. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] Figure 2 This is a schematic diagram of the connection between the piston and the grouting pipe.

[0025] Figure 3 This is a detailed drawing of the limit device.

[0026] Figure 4 This is a schematic diagram of the initial stage of grouting using advanced small-diameter guide pipes.

[0027] Figure 5 This is a schematic diagram of the grouting process using advanced small guide pipes.

[0028] Figure 6 This is a schematic diagram of the completion of grouting using advanced small-diameter guide pipes. Detailed Implementation

[0029] like Figure 1 As shown in Figure 6, a tunnel pre-conduit pipe mainly consists of a pre-conduit pipe body 1 and a grouting pipe 2. The grouting pipe 2 is located inside the pre-conduit pipe body 1, and its outer diameter is smaller than the inner diameter of the pre-conduit pipe body 1 so that it can move freely within the pre-conduit pipe body 1. Specifically, the pre-conduit pipe body 1 is made of Φ42×4mm hot-rolled seamless steel pipe, and the grouting pipe 2 is made of Φ22×3mm hot-rolled seamless steel pipe.

[0030] A piston 3 is detachably installed at the front end of the grouting pipe 2. The piston 3 is sealed inside the body of the advanced small guide tube 1. The front end of the piston 3 is provided with several grouting holes, which are connected to the grouting pipe 2. A check valve is provided inside the piston 3 to control the opening and closing of each grouting hole 2.

[0031] The inner wall of the rear end of the advanced small guide tube body 1 is provided with a limiting device 4 to prevent the piston 3 from falling out, and the grouting pipe 2 can pass through the limiting device 4.

[0032] Ideally, the piston 3 is provided with a grouting port for the insertion of the grouting pipe 2, and the grouting port connects the grouting pipe 2 to each grouting hole. Specifically, the grouting port is located at the rear end of the piston 3, and the grouting pipe 2 is inserted into the grouting port and connected to each grouting hole.

[0033] Preferably, the check valve is a spring-loaded check valve, located at the connection between the grouting port and the piston 3. The spring-loaded check valve automatically opens or closes based on the grouting pressure. After grouting is complete, the grouting pipe 2 is removed, and the spring-loaded check valve automatically seals the grouting port to prevent backflow of grout.

[0034] Ideally, piston 3 is conical, with the grouting hole located on the conical surface and tip of piston 3. Piston 3 can be made of an elastic material, such as rubber, possessing a certain degree of flexibility and sealing performance, while also being able to withstand a certain grouting pressure without being damaged.

[0035] Ideally, piston 3 and grouting pipe 2 should be connected by thread for easy disassembly.

[0036] Ideally, the limiting device 4 is in the shape of a cone frustum, and the inner diameter of the limiting device 4 is larger than the outer diameter of the grouting pipe 2. The limiting device 4 is used to stop the piston 3 to prevent it from falling out, and will not interfere with the passage of the grouting pipe 2.

[0037] A grouting method for a tunnel pre-conduit pipe, based on the aforementioned tunnel pre-conduit pipe, mainly consists of the following steps:

[0038] S1. Determine the installation position and angle of the advance guide tube at the tunnel face, and use drilling equipment to drill a hole at the predetermined position. The diameter of the hole is slightly larger than the outer diameter of the advance guide tube body 1, generally the outer diameter of the advance guide tube body 1 plus 10-20mm. During the insertion of the advance guide tube body 1, a drilling machine can be used to assist in the hole insertion to ensure that the advance guide tube body 1 is firmly installed.

[0039] S2. Insert the pre-drilled guide pipe into the borehole, ensuring that the tip of the pre-drilled guide pipe reaches the designed depth and is in close contact with the surrounding rock. Simultaneously, install a grout stopper 5 at the pipe opening to seal the gap between the borehole wall and the pre-drilled guide pipe, preventing grout backflow within the gap. Alternatively, after the pre-drilled guide pipe body 1 is installed, connect the grouting pipe 2 to the piston 3 pre-installed inside the pre-drilled guide pipe body 1.

[0040] S3. Connect the rear end of the grouting pipe 2 to the grouting equipment, and extend the front end of the grouting pipe 2 into the inner front end of the pre-guide pipe body 1. The insertion depth is generally 0.5 to 1.0 meters to ensure that the grout can be injected from the bottom of the borehole. The length of the grouting pipe 2 is determined according to the length of the pre-guide pipe body 1. It is necessary to ensure that the grouting pipe 2 can extend from the bottom of the hole to the hole opening, and reserve a certain connection length for connecting the grouting equipment.

[0041] S4. Start the grouting equipment. The grout is injected into the gap between the advanced small guide tube body 1 and the surrounding rock through the grouting pipe 2. As the grouting pressure increases, the piston 3 is pushed by the grout, which drives the grouting pipe 1 to move towards the borehole opening. During the movement, the grout continuously fills the gap, achieving uniform grouting.

[0042] S5. When the piston 3 moves to the position of the limit device 4, stop grouting, remove the grouting pipe 2, and close the check valve. The spring-loaded check valve will automatically close after the grouting pipe 2 is removed.

[0043] Ideally, the grouting pipe 2 should be removed, cleaned, and inspected before being used for the next grouting operation of the advanced small guide pipe body 1. In other words, the grouting pipe 2 can be reused, which helps to save costs.

Claims

1. A grouting method for a tunnel pre-drilling small guide pipe, characterized in that: The tunnel pre-conduit pipe includes a pre-conduit pipe body (1) and a grouting pipe (2). The grouting pipe (2) is located inside the pre-conduit pipe body (1), and its outer diameter is smaller than the inner diameter of the pre-conduit pipe body (1). A piston (3) is detachably installed at the front end of the grouting pipe (2). The piston (3) is sealed inside the pre-conduit pipe body (1). The front end of the piston (3) is provided with several grouting holes. The grouting holes are connected to the grouting pipe (2). A check valve for controlling the opening and closing of each grouting hole is provided inside the piston (3). A limiting device (4) for preventing the piston (3) from falling out is provided on the inner wall of the rear end of the pre-conduit pipe body (1). The grouting pipe (2) can pass through the limiting device (4). The piston (3) is provided with a grouting port for the grouting pipe (2) to be inserted. The grouting port is connected between the grouting pipe (2) and each grouting hole. The check valve is a spring check valve. The spring check valve is set at the connection position between the grouting port and the piston (3). The spring check valve is automatically opened or closed by the grouting pressure. The grouting method includes the following steps: S1. Determine the installation position and angle of the advance guide pipe at the tunnel face, and use drilling equipment to drill holes at the predetermined positions; S2. Insert the pre-drilled guide pipe into the borehole, ensuring that the front end of the pre-drilled guide pipe reaches the design depth and is in close contact with the surrounding rock. At the same time, install a grout stop plug (5) at the pipe opening to seal the gap between the borehole wall and the pre-drilled guide pipe. S3. Connect the rear end of the grouting pipe (2) to the grouting equipment, and extend the front end of the grouting pipe (2) into the front end of the advanced small guide tube body (1) to ensure that the grout can be injected from the bottom of the borehole. S4. Start the grouting equipment. The grout is injected into the gap between the advanced small guide tube body (1) and the surrounding rock through the grouting pipe (2). As the grouting pressure increases, the piston (3) is pushed by the grout, which drives the grouting pipe (2) to move towards the borehole opening. During the movement, the grout continuously fills the gap to achieve uniform grouting. S5. When the piston (3) moves to the position of the limiting device (4), stop grouting, remove the grouting pipe (2), and close the check valve.

2. The grouting method for tunnel pre-conduit pipes according to claim 1, characterized in that: The piston (3) is conical, and the grouting hole is located on the conical surface and tip of the piston (3).

3. The grouting method for tunnel pre-conduit pipes according to claim 1, characterized in that: The piston (3) and the grouting pipe (2) are connected by thread.

4. The grouting method for tunnel pre-conduit pipes according to claim 1, characterized in that: The limiting device (4) is in the shape of a cone frustum, and the inner diameter of the limiting device (4) is larger than the outer diameter of the grouting pipe (2).

5. The grouting method for tunnel pre-conduit pipes according to claim 1, characterized in that: After the grouting pipe (2) is removed, it is cleaned and inspected for use in the grouting operation of the next advanced small guide tube body (1).

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