Tunnel pipe shed construction method

Abstract

The invention relates to the technical field of tunnel construction, and provides a tunnel pipe shed construction method. The tunnel pipe shed construction method comprises the following steps that S1, a guide wall is poured on the arch portion of the outer side of a tunnel design contour line, and a plurality of guide pipes are arranged on the guide wall at intervals in the circumferential direction of the guide wall; s2, shed pipe mounting holes are drilled in the length direction of the guide pipe; s3, shed pipes with grouting holes penetrate through the guide pipes and are placed in the shed pipe mounting holes in a one-to-one correspondence mode; and S4, grouting is conducted on the interior of the shed pipe. The tunnel pipe shed construction method overcomes the defect that in the prior art, a tunnel pipe shed construction method is insufficient in construction precision, and the high-precision tunnel pipe shed construction method is achieved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for constructing a tunnel pipe roof. Background Technology

[0002] Tunnel pipe roof construction is a pre-reinforcement technique used before tunnel excavation to enhance the stability of the tunnel entrance and surrounding rock mass, prevent collapse, and control surface subsidence. It is typically used in tunnel projects in complex environments such as those with poor geological conditions, abundant groundwater, or those requiring tunneling through buildings.

[0003] Existing tunnel pipe roof construction methods suffer from insufficient construction precision, resulting in low construction efficiency and increased construction costs. Summary of the Invention

[0004] This invention provides a tunnel pipe roof construction method to address the shortcomings of insufficient construction accuracy in existing tunnel pipe roof construction methods, thereby achieving a high-precision tunnel pipe roof construction method.

[0005] The tunnel pipe roof construction method provided by this invention includes: A guide wall is cast on the outer arch of the tunnel design outline, and the guide wall is provided with multiple guide pipes at intervals along its circumference; Drill holes for the shed pipe installation along the length of the guide pipe; The shed pipe with grouting holes is passed through the guide pipe and placed into the shed pipe installation hole one by one; Grout is injected into the inside of the shed pipe.

[0006] According to a tunnel pipe roof construction method provided by the present invention, the step of casting a guide wall on the outer arch of the tunnel design outline, wherein the guide wall is provided with a plurality of guide pipes spaced apart along its circumference, includes: According to the tunnel design outline, the predetermined range of its arch is measured and laid out, and the foundation is excavated and treated in stages. Based on the completed foundation, the casting formwork for the guide wall is installed and reinforced. Based on the installed template, multiple guide tubes are sequentially and spaced apart inside the casting template; After the guide tube is fixed, concrete is poured symmetrically into the pouring template and compacted in layers by vibration.

[0007] According to a tunnel pipe roof construction method provided by the present invention, the outer insertion angle of the guide pipe is 1°~3°.

[0008] According to a tunnel pipe roof construction method provided by the present invention, drilling pipe roof installation holes along the length direction of the guide pipe includes: The installation holes of the greenhouse pipes are numbered sequentially; Erect a work platform and install a drilling rig on the work platform; The drill rod is calibrated using a total station to ensure that the axis of the drill rod coincides with the axis of the guide tube, thus ensuring that the drilling direction matches the external insertion angle of the guide tube. Drill holes alternately from the highest point in the middle to the left and right sides; At each predetermined drilling depth, the external insertion angle is checked with an inclinometer. If the deviation exceeds the limit, drilling is paused for grouting or re-drilling correction.

[0009] According to a tunnel pipe roof construction method provided by the present invention, the step of drilling pipe roof installation holes along the length direction of the guide pipe further includes: Use the drill rod and drill bit to repeatedly sweep the hole to remove slag and ensure that the hole diameter and depth meet the requirements to prevent clogging; High-pressure air is used to clean drilling cuttings from the bottom of the hole to the opening to ensure that there are no residual debris inside the hole.

[0010] According to a tunnel pipe roof construction method provided by the present invention, the spacing between the grouting holes is 15cm to 20cm; The diameter of the grouting hole is 10mm to 16mm.

[0011] According to a tunnel pipe roof construction method provided by the present invention, the pipe roof is composed of multiple pipe sections spliced ​​together, the splicing points of two adjacent pipe sections are staggered, and the distance between the splicing points of two adjacent pipe sections is at least 1m.

[0012] According to a tunnel pipe roof construction method provided by the present invention, the end section of the pipe roof is provided with a grout-stopping section.

[0013] According to a tunnel pipe roof construction method provided by the present invention, a support frame is provided inside the pipe roof to improve the rigidity of the pipe roof.

[0014] According to a tunnel pipe roof construction method provided by the present invention, the grouting inside the pipe roof includes: Grouting is performed at intervals from low to high, according to the location of the shed pipe.

[0015] The tunnel pipe roof construction method provided by this invention achieves precise control over the installation position of the pipe roof by casting a guide wall on the outer arch of the tunnel's designed outline and setting multiple guide pipes at circumferential intervals around the guide wall. The guide wall, as a reference structure, ensures that the drilling direction of the pipe roof installation holes is consistent with the tunnel's designed outline, thereby reducing construction errors. Pipe roofs with grouting holes are passed through the guide pipes and placed one-to-one into the corresponding installation holes, further ensuring the positioning accuracy and installation quality of the pipe roofs. In this method, grout is injected into the pipe roofs, filling rock fissures and consolidating the surrounding rock mass, thereby enhancing the stability of the tunnel entrance and surrounding rock mass, preventing collapse, and controlling surface subsidence. This method, through the precise design of the guide wall and guide pipes, effectively improves construction accuracy and efficiency, reduces construction costs, and is suitable for tunnel engineering in poor or complex geological conditions. Attached Figure Description

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

[0017] Figure 1 This is one of the flowcharts of the tunnel pipe roof construction method provided by the present invention; Figure 2 This is the second flowchart of the tunnel pipe roof construction method provided by the present invention; Figure 3 This is the third flowchart of the tunnel pipe roof construction method provided by the present invention. Detailed Implementation

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

[0019] Reference Figures 1 to 3 The tunnel pipe roof construction method provided by the present invention includes the following steps: S1. A guide wall is poured on the outer arch of the tunnel design outline, and multiple guide pipes are spaced apart along the circumference of the guide wall.

[0020] Specifically, a concrete arch support is constructed as a guide wall within a 150° range outside the tunnel's designed outline. The guide wall is made of C20 concrete, with a longitudinal length of 2m and a thickness of 1m. The guide wall foundation should have sufficient bearing capacity of no less than 150 kPa. An I-beam arch frame is embedded within the guide wall, welded integrally with the guide pipe. The guide pipe is a 6mm thick Φ133 seamless steel pipe, fixed with Φ8 coiled steel bars. The circumferential spacing of the guide pipes is 40cm, and accurate installation is required. The guide wall foundation needs to be embedded 50cm into the pipe roof working platform. Before constructing the arch support, excavation is carried out in steps, with the upper step height near the arch support line to meet working height requirements.

[0021] As the positioning pipe for the shed pipe, the accuracy of its planar position, inclination angle, and external insertion angle directly affects the quality of the shed pipe. The positioning of the guide pipe should be accurately determined on the I-beam arch using a total station. The inclination angle of the guide pipe should be set using a leveling rod and a slope plate, and the external insertion angle should be set using the front-to-back difference method. The guide pipe should be firmly welded to the I-beam arch to prevent displacement during concrete pouring.

[0022] S2. Drill the installation hole for the roof pipe along the length of the guide pipe. Specifically, the drill bit of the drilling machine should pass through the guide pipe and drill into the tunnel along the extension line of the guide pipe, so that the installation hole for the roof pipe and the hole in the guide pipe are on the same straight line.

[0023] S3. Pass the shed pipes with grouting holes through the guide pipe and place them one by one into the shed pipe installation holes. The spacing between the grouting holes is 15cm to 20cm; the diameter of the grouting holes is 10mm to 16mm.

[0024] S4. Grouting inside the greenhouse pipe. The grout can be cement grout. After the cement grout is injected into the greenhouse pipe, it is embedded into the inner wall of the installation hole through the grouting hole, thus making the greenhouse pipe more firmly fixed.

[0025] The tunnel pipe roof construction method provided by this invention achieves precise control over the installation position of the pipe roof by casting a guide wall on the outer arch of the tunnel's designed outline and setting multiple guide pipes at circumferential intervals around the guide wall. The guide wall, as a reference structure, ensures that the drilling direction of the pipe roof installation holes is consistent with the tunnel's designed outline, thereby reducing construction errors. Pipe roofs with grouting holes are passed through the guide pipes and placed one-to-one into the corresponding installation holes, further ensuring the positioning accuracy and installation quality of the pipe roofs. In this method, grout is injected into the pipe roofs, filling rock fissures and consolidating the surrounding rock mass, thereby enhancing the stability of the tunnel entrance and surrounding rock mass, preventing collapse, and controlling surface subsidence. This method, through the precise design of the guide wall and guide pipes, effectively improves construction accuracy and efficiency, reduces construction costs, and is suitable for tunnel engineering in poor or complex geological conditions.

[0026] In some embodiments of the present invention, step S1 includes: S1.1. Based on the tunnel design outline, conduct surveying and layout within the predetermined range of its arch to determine the specific location and dimensions of the guide wall. Subsequently, excavate and treat the foundation in stages to ensure that the foundation surface is flat and its bearing capacity meets the design requirements, providing stable support conditions for the subsequent pouring of the guide wall.

[0027] S1.2. Based on the completed foundation, install the casting formwork for the guide wall. The installation of the casting formwork must be strictly based on the measurement and layout results to ensure that it is consistent with the tunnel design outline. After installation, the casting formwork is reinforced to prevent deformation or displacement during concrete pouring, ensuring the geometric dimensions and shape accuracy of the guide wall.

[0028] S1.3. Using the installed template, fix multiple guide pipes sequentially and at intervals inside the pouring template. The fixing positions of the guide pipes must be precisely arranged according to the design requirements to ensure that they are evenly distributed along the circumference of the guide wall and remain parallel to or at a preset angle to the tunnel design outline. The guide pipes can be fixed by welding, bolting, or other reliable methods to ensure that they do not shift during the concrete pouring process.

[0029] S1.4 After the guide pipe is fixed, pour concrete symmetrically into the casting formwork. Concrete pouring must be done in layers, with each layer's thickness controlled within a reasonable range to avoid insufficient concrete density due to excessively rapid pouring. After each layer is poured, use a vibrator to compact the concrete, ensuring full contact between the concrete and the guide pipe and formwork, eliminating internal air bubbles, and improving the overall strength and stability of the guide wall.

[0030] Through the above steps, step S1 achieves precise construction of the guide wall, providing a reliable guiding benchmark for the subsequent installation of the tunnel pipe roof, thereby improving the overall accuracy and efficiency of tunnel pipe roof construction.

[0031] In some possible embodiments, step S1.2 includes: S1.2.1 Bottom Formwork Installation: After excavation of the guide wall and ear wall, a 15cm C20 concrete pad is poured after leveling the bottom. The concrete elevation is strictly controlled during pouring. Four I18 steel arch frames are erected on the concrete pad as bottom formwork supports. The bottom of the steel arch frames is supported by Φ42 steel pipes and I18 I-beams. 5cm thick wooden formwork is laid on the steel arch frames, with a length of not less than 220cm and a width of 30cm. Each wooden plank must be checked with a level; otherwise, steel plates are welded to the bottom formwork for adjustment. The bottom formwork installation must ensure flatness, tight fit, and firmness, and loosening is strictly prohibited.

[0032] S1.2.2 Arch Installation: After the bottom formwork is installed, install two I18 I-beam arch frames with a spacing of 50cm. The two arch frames are connected by longitudinal connecting bars of Φ22 threaded steel. Before installing the I-beams inside the guide wall, a trial assembly should be conducted at the steel reinforcement plant. After the trial assembly is qualified, the on-site installation should be carried out. After installation, the position, arch frame spacing, and verticality should be checked.

[0033] S1.2.3, Guide Pipe Installation: The guide pipes are Φ133×6mm, 1m long, hot-rolled seamless steel pipes, with a circumferential spacing of 40cm, totaling 50 pipes. When laying the pipes, pay attention to controlling the external insertion angle, which should be 1°~3°. Use a total station to determine the planar position on the I-beam frame using the coordinate method. Use a measuring tape to measure the spacing of the orifice pipes, and use the front-to-back difference method to set the external insertion angle of the orifice pipes. The guide pipes should be firmly welded to the I-beam to prevent displacement during concrete pouring. The guide pipes are made of Φ8 steel bars welded to the I-beam, with a length of 60cm.

[0034] S1.2.4 Side Formwork Installation: 15mm bamboo plywood is used for the side formwork, cut to the appropriate size according to the design drawings to ensure the thickness of the guide wall. Φ14 steel bars are used for reinforcement, with the ends of the steel bars directly anchored to the slope surface. The side formwork installation is required to be on the same vertical plane. The outer side of the side formwork is reinforced by welding Φ14 steel bars, and steel pipe diagonal bracing is made on the outer side to ensure the stability of the formwork.

[0035] S1.2.5 Top Formwork Installation: The top formwork of the guide wall is the same as the bottom formwork, both using 5cm wooden boards. The ends of the formwork are closely attached to the slope surface, and the joints between the formwork are tight. The formwork is threaded with tie bars from top to bottom, and then connected with circumferential steel bars. During the installation of the top formwork, pouring holes should be reserved. The reserved holes are 30×30cm in size and spaced 3m apart to facilitate pouring and vibration operations.

[0036] S1.2.6 Concrete Pouring and Curing: C20 concrete is used for the guide wall. During concrete pouring, symmetrical pouring on both sides is required, with a pouring window height difference not exceeding 1m. Concrete vibration should be performed through the pre-reserved holes, with two vibrators simultaneously vibrating from both sides. When pouring to the pre-reserved holes, they should be sealed promptly. The pouring process should be gradual, and the pouring speed should be strictly controlled to prevent formwork bursting or running out. Depending on the actual situation, the foundations on both sides of the arch foot can be poured in advance or simultaneously. The top and side forms should be removed after the guide wall concrete reaches 75% strength, ensuring no chipped edges or corners during removal. The bottom formwork should be removed after the concrete strength reaches 100%. Any defects found on the concrete surface after removal should be promptly repaired and finished. Concrete curing should be carried out according to requirements to ensure concrete strength. The guide holes should be numbered from left to right.

[0037] In some embodiments of the present invention, step S2 includes: S2.1. Number the pipe installation holes sequentially. Based on the design requirements and the layout of the guide pipes, number each pipe installation hole and record its corresponding location information to ensure accurate identification and management of each hole during subsequent construction. Specifically, the holes can be numbered sequentially from left to right (1-50) along the shape of the guide wall, or from right to left (1-50). It should be noted that the number of pipe installation holes is not limited to 50 and can be designed according to the actual situation.

[0038] During the marking process, the specific coordinates and numbers of each pipe installation hole must be determined based on the tunnel design drawings and the layout of the guide pipes. After marking, the holes must be marked on the construction site, and the location information, number, and corresponding design parameters (such as external insertion angle, depth, etc.) of each hole must be recorded in detail in the construction log to facilitate rapid positioning and verification during subsequent construction. Furthermore, care must be taken to avoid duplicate or omitted numbers during the marking process to ensure the uniqueness and accuracy of each hole location.

[0039] S2.2. Erect a working platform and install the drilling rig on it. The erection of the working platform must meet the space and stability requirements for drilling operations to ensure that the drilling rig can operate smoothly during construction.

[0040] The work platform is constructed in two tiers, upper and lower. An excavator is used to level the site, and drilling proceeds from the higher hole position to the lower hole position, using a skip-hole drilling method. First, even-numbered holes are drilled on the upper part of the first platform, and then odd-numbered holes are drilled. The site for the down-the-hole drill should be on a stable foundation to prevent uneven settlement, swaying, or displacement of the drill during drilling, which could affect the drilling quality.

[0041] It should be noted that the construction of the work platform must be designed according to the tunnel cross-sectional dimensions and construction space requirements to ensure that the platform has sufficient load-bearing capacity and stability. After the platform is erected, a safety inspection must be conducted to confirm its stability and safety. The installation position of the drilling rig must be adjusted according to the marked hole positions to ensure that the center line of the drilling rig is aligned with the axis of the guide pipe. After the drilling rig is installed, a trial run must be conducted to check whether its various functions are normal and to ensure stable operation during construction.

[0042] S2.3. Use a total station to calibrate the drill rod so that its axis coincides with the axis of the guide tube, ensuring that the drilling direction matches the external insertion angle of the guide tube. Through precise measurement and adjustment with a total station, correct the angle and position of the drill rod to ensure that it is consistent with the axis of the guide tube, thereby guaranteeing that the drilling accuracy and direction meet the design requirements.

[0043] It should be noted that the calibration process for the total station must be strictly performed according to the measurement specifications. First, set up the total station on a stable measurement benchmark and measure the initial position of the drill rod, recording its deviation from the axis of the guide tube. Based on the measurement results, adjust the angle and position of the drill rod so that its axis coincides with the axis of the guide tube. After calibration, the total station must be used again for verification to ensure that the angle and direction of the drill rod meet the design requirements. If any deviation is found, readjustment is required until the accuracy requirements are met.

[0044] S2.4. Drilling should proceed alternately from the highest point in the middle to the left and right sides. Starting from the highest point in the middle of the tunnel arch, drilling should be carried out symmetrically to both sides, using an alternate-hole drilling method to avoid stress concentration or deformation of the rock mass caused by continuous drilling, thus ensuring the stability of the construction process. That is, drill the holes at odd-numbered positions first, then drill the holes at even-numbered positions. Alternatively, drill the holes at even-numbered positions first, then drill the holes at odd-numbered positions. Drilling should begin at a low speed and low pressure. After the hole has reached 10m, the drilling speed and pressure can be gradually adjusted according to the geological conditions. In areas with good rock quality, the hole can be formed in one go. If hole collapse or drill bit jamming occurs during drilling, it is necessary to follow the casing or inject grout before continuing drilling.

[0045] Starting drilling from the highest point in the middle of the tunnel arch effectively controls the stress distribution in the rock mass during construction, preventing rock deformation or collapse caused by improper drilling sequence. During drilling, the principle of alternating borehole drilling must be strictly followed, meaning odd-numbered boreholes are drilled first, followed by even-numbered boreholes. This sequence reduces interference between adjacent boreholes, ensuring drilling quality and construction safety.

[0046] S2.5. At each predetermined drilling depth, the external insertion angle is checked using an inclinometer. If the deviation exceeds the limit, drilling is paused for grouting or re-drilling correction. During the drilling process, the external insertion angle of the borehole is checked using an inclinometer at regular intervals. If the deviation is found to exceed the allowable range, drilling is stopped immediately, and correction is performed by grouting or readjusting the drill rod position to ensure that the accuracy and direction of the borehole meet the design requirements.

[0047] It should be noted that during drilling, a reasonable inspection interval depth (e.g., once every 1 meter of drilling) must be set according to design requirements and geological conditions. When using an inclinometer to check the borehole's external angle, the inspection data must be recorded and compared with the design value. If a deviation is found to exceed the allowable range, drilling must be stopped immediately, and the cause of the deviation analyzed. For deviations caused by loose rock or groundwater, the rock mass can be reinforced with grout before drilling can continue; for deviations caused by improper drilling rig angle adjustment, the drill rod angle must be readjusted and drilling repeated.

[0048] S2.6. Use the drill rod and drill bit to repeatedly sweep the hole to remove floating debris and ensure that the hole diameter and depth meet the requirements, preventing hole blockage. After drilling is completed, use the drill rod and drill bit to repeatedly sweep the hole to remove floating debris and residue, ensuring that the hole diameter and depth meet the design requirements, and avoiding hole blockage caused by the accumulation of floating debris.

[0049] It should be noted that during the hole cleaning process, a drill bit and drill rod matching the hole diameter must be used, and the hole should be repeatedly cleaned by rotating at a low speed. Care must be taken to control the feed speed of the drill rod during cleaning to avoid damage to the hole wall or accumulation of slag due to excessive speed. After cleaning, the hole diameter and depth must be checked using measuring tools to ensure they meet design requirements. If the hole diameter or depth is found to be insufficient, the hole cleaning or additional drilling must be performed.

[0050] S2.7 Use high-pressure air to clean the drill cuttings from the bottom of the hole to the opening, ensuring that there are no residual debris inside the hole. After cleaning the hole, use high-pressure air to blow from the bottom of the hole to the opening to thoroughly remove the drill cuttings and fine particles inside the hole, ensuring that the hole is clean and free of debris, providing good conditions for the subsequent installation of the shed pipe.

[0051] During high-pressure air cleaning, the air hose must be inserted to the bottom of the hole and moved upwards slowly to ensure that drill cuttings are completely blown out of the hole. Care must be taken to control the air pressure during cleaning to avoid damage to the hole wall or loosening of the rock mass due to excessive pressure. After cleaning, the hole should be inspected using an endoscope or lighting tool to confirm that no debris remains. If drill cuttings are still found, the cleaning process must be repeated until the hole is completely clean.

[0052] Through the above-mentioned detailed steps, step S2 achieved high-precision drilling of the pipe installation holes, ensuring that the drilling direction, diameter and depth met the design requirements, laying the foundation for accurate installation of the pipes, thereby improving the overall quality and efficiency of tunnel pipe roof construction.

[0053] In some embodiments of the present invention, the greenhouse pipe is composed of multiple pipe sections spliced ​​together, with the joints of adjacent pipe sections staggered and the distance between the joints of adjacent pipe sections being at least 1m. A grout-stopping section is provided at the end of the pipe. The greenhouse pipe is made of hot-rolled seamless steel pipe with a wall thickness of not less than 8mm. The length of each pipe section is 4m to 6m, and two pipe sections are connected by threaded connections. Each pipe section at its end has a conical head with a length of 20cm. The pipe sections are connected securely by threaded connections, with each thread being 15cm long. The pipe arrangement for odd-numbered holes is: 2m + 5.8m + 5.8m + 5.8m + 5.8m + 5.8m + 4m, and the pipe arrangement for even-numbered holes is: 4m + 5.8m + 5.8m + 5.8m + 5.8m + 2m. The jacking of the greenhouse pipes employs a combination of a loader and a pipe shed drilling rig. First, a guide hole larger than the diameter of the greenhouse pipe is drilled. Then, a loader, with manual assistance, pushes the pipe forward. Initially, the pipe is fed manually, and later, the drilling rig is used to push it forward until it reaches the bottom of the hole and the designed length.

[0054] The greenhouse pipe sections are threaded on a specialized pipe bed, and grouting holes with a diameter of 10mm to 16mm are drilled around them, spaced 15cm to 20cm apart in a quincunx pattern. A 2m to 3m section without drilling is left at the end to stop the grouting. The pipe head is welded into a conical shape for easy insertion into the holes. To increase the bending resistance and rigidity of the greenhouse pipe, a support frame is added inside the steel pipe. Specifically, the support frame can be a reinforcing cage, consisting of four φ18 main reinforcing bars and fixing rings. The fixing rings are made of φ42 steel pipes, 5cm wide, with a wall thickness of 3.5mm, spaced 100cm apart.

[0055] In some embodiments of the present invention, step S4 includes: S4.1 Construction Preparation. Construction personnel should wear safety helmets, gloves, and waterproof boots. Personnel mixing the grout should wear safety goggles and high-top rubber boots. High-pressure water should be used to flush away debris inside the pipe shed, proceeding from bottom to top. To improve the bending resistance of the steel pipes, a reinforcing cage is added inside the guide pipe. The reinforcing cage consists of four main reinforcing bars and fixing rings. The main reinforcing bars have a diameter of φ18mm. The fixing rings are short pipe sections, welded to the main reinforcing bars, and installed at 1m intervals. The short pipe sections can be connected using 5cm long φ42 steel pipes with a wall thickness of 3.5mm. After installing the perforated steel pipes, grouting pipes and vent pipes are inserted into the steel pipes. The vent pipe must be inserted to the bottom of the hole. The gaps at the hole opening are sealed with concrete to ensure a tight seal.

[0056] S4.2 Grout Mixing. Grouting Material: The grouting material is single-component cement grout. The cement grade should be 425 or higher. The water-cement ratio is generally 0.5:1 to 2:1. The grout-bound stone strength should not be less than M10, and should be adjusted according to site conditions. The water-cement ratio can be slightly higher at the beginning of grouting, and then gradually decreased. The initial grout concentration is determined based on the borehole grout intake. Each batch of grout should be mixed for no less than 10 minutes. The grout should be mixed evenly without lumps or sediment; otherwise, the mixing time should be appropriately extended. The grout can only be injected into the pipe roof after it is evenly mixed. The grout should be mixed and used immediately on site, and should have good fluidity and injectability. When the surrounding rock is fractured and groundwater is abundant, a water glass-water glass two-component grout should be used. When using chemical grout, attention should be paid to corrosion and toxicity prevention.

[0057] S4.3 Grouting. Grouting operations should be carried out strictly in accordance with the operating procedures of the grouting machine. Thorough preparations should be made before grouting, especially the inspection and maintenance of the equipment. Any problems should be promptly addressed to ensure the equipment is in good working order. During grouting, the grouting pipe opening must not be pointed directly at the human body to avoid injury from the high-pressure grout. During the operation, precautions should also be taken to prevent the grouting pipe from bursting and causing injury to construction personnel.

[0058] Before starting grouting, the grouting pipeline system should be carefully inspected, including the mixer, joints, pipe clamps, valves, etc. Any damaged parts should be replaced immediately. Damaged joints and valves must not be used to prevent tripping accidents under high pressure. All pipelines should be connected outside the tunnel beforehand and pressure tested using clean water. During the pressure test, any blockages in the pipeline or leaks at the joints should be addressed to ensure all components of the pipeline system are in good working order.

[0059] The grouting sequence should proceed alternately from low to high and from bottom to top. During the grouting process, all disassembled joints and valves should be cleaned by designated personnel in a timely manner for future use. The grouting pressure of the grouting machine should be controlled at: initial pressure 0.5MPa~1.0MPa, final pressure 2.0MPa~2.5MPa. After the grout is filled, the pressure should be maintained for 15 minutes before stopping the grouting.

[0060] The grouting volume should meet the design requirements, generally 1.5 times the diameter of the borehole cylinder. If the grouting volume exceeds the limit and the pressure requirement is not met, the grout concentration should be adjusted and grouting should continue to ensure that the rock mass around the borehole and the pores around the steel pipe are fully filled. The grouting pipe and grout stop valve should be welded to the tail end of the pre-grouted pipe roof, and an air vent should be reserved. Grouting should be stopped by opening the grout stop valve after the grouting reaches the design final pressure and grouting continues for more than 10 minutes.

[0061] During grouting, grout the odd-numbered holes first, then the even-numbered holes. If the grouting pump pressure suddenly increases, pipe blockage may occur; in this case, the machine should be stopped immediately for inspection, and grouting can only continue after the cause has been identified. If deformation or damage to the support is found during grouting, grouting should be stopped immediately, and measures should be taken. If grout leakage occurs, the leakage holes should be plugged promptly. During grouting construction, on-site technicians should carefully fill out grouting records and analyze and improve the operation as needed. After grouting is completed, all machinery and equipment should be thoroughly cleaned, especially the mixer, grouting pipes, joints, valves, and grouting tanks, for use in subsequent grouting stages. A professional electrician should be on-site during construction to promptly troubleshoot any circuit or electrical equipment malfunctions, ensuring smooth construction.

[0062] 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; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for constructing a tunnel pipe roof, characterized in that, include: A guide wall is cast on the outer arch of the tunnel design outline, and the guide wall is provided with multiple guide pipes at intervals along its circumference; Drill holes for the shed pipe installation along the length of the guide pipe; The shed pipe with grouting holes is passed through the guide pipe and placed into the shed pipe installation hole one by one; Grout is injected into the inside of the shed pipe.

2. The tunnel pipe roof construction method according to claim 1, characterized in that, The method of casting a guide wall on the outer arch of the tunnel design outline, wherein the guide wall is provided with multiple guide pipes spaced apart along its circumference, includes: According to the tunnel design outline, the predetermined range of its arch is measured and laid out, and the foundation is excavated and treated in stages. Based on the completed foundation, the casting formwork for the guide wall is installed and reinforced. Based on the installed template, multiple guide tubes are sequentially and spaced apart inside the casting template; After the guide tube is fixed, concrete is poured symmetrically into the pouring template and compacted in layers by vibration.

3. The tunnel pipe roof construction method according to claim 2, characterized in that, The external insertion angle of the guide tube is 1°~3°.

4. The tunnel pipe roof construction method according to claim 1, characterized in that, Drilling the installation hole for the shed pipe along the length direction of the guide pipe includes: The installation holes of the greenhouse pipes are numbered sequentially; Erect a work platform and install a drilling rig on the work platform; The drill rod is calibrated using a total station to ensure that the axis of the drill rod coincides with the axis of the guide tube, thus ensuring that the drilling direction matches the external insertion angle of the guide tube. Drill holes alternately from the highest point in the middle to the left and right sides; At each predetermined drilling depth, the external insertion angle is checked with an inclinometer. If the deviation exceeds the limit, drilling is paused for grouting or re-drilling correction.

5. The tunnel pipe roof construction method according to claim 4, characterized in that, Drilling the pipe installation hole along the length of the guide tube also includes: Use the drill rod and drill bit to repeatedly sweep the hole to remove slag and ensure that the hole diameter and depth meet the requirements to prevent clogging; High-pressure air is used to clean drilling cuttings from the bottom of the hole to the opening to ensure that there are no residual debris inside the hole.

6. The tunnel pipe roof construction method according to any one of claims 1-5, characterized in that, The spacing between the grouting holes is 15cm to 20cm; The diameter of the grouting hole is 10mm to 16mm.

7. The tunnel pipe roof construction method according to claim 4, characterized in that, The shed pipe is composed of multiple shed pipe sections spliced ​​together, with the splicing points of two adjacent shed pipes staggered, and the distance between the splicing points of two adjacent shed pipes is at least 1m.

8. The tunnel pipe roof construction method according to any one of claims 1-5, characterized in that, The end section of the shed pipe is equipped with a grout-stopping section.

9. The tunnel pipe roof construction method according to any one of claims 1-5, characterized in that, The shed pipe is equipped with an internal support frame, which is used to improve the rigidity of the shed pipe.

10. The tunnel pipe roof construction method according to any one of claims 1-5, characterized in that, The grouting inside the greenhouse pipe includes: Grouting is performed at intervals from low to high, according to the location of the shed pipe.

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