Large-diameter steel lining construction method in narrow and limited space

Abstract

The invention discloses a construction method for a large-diameter steel lining in a narrow limited space. The construction method comprises the following steps: measuring and setting out the axis and elevation of a steel pipe transportation track; mounting a track on a tunnel bottom plate according to a survey lofting result; the steel pipe is hoisted to the track, steel wheels arranged on the steel pipe are matched with the track, and the steel pipe is dragged to a mounting position in the hole along the track through a traction mechanism; after the steel pipe is conveyed to the installation position, the steel pipe mileage and elevation are adjusted to the designed mileage and the designed elevation; after the mileage and elevation of the steel pipe are adjusted in place, the steel wheel and the track are welded and fixed, and meanwhile the steel pipe is fixed through a plurality of anchoring points evenly distributed in the circumferential direction; welding circumferential welding seams of the steel pipe by adopting a single-side welding and double-side forming welding process; carrying out nondestructive testing on a welding seam after the steel pipe is welded; and steel pipe joint coating corrosion prevention. According to the method, construction interference is reduced, construction efficiency is improved, construction progress is accelerated, potential safety hazards are reduced, and cost is saved by optimizing steel pipe in-hole transportation and welding processes.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel lining construction, and in particular to a large-diameter steel lining construction method in a narrow and confined space. Background Art

[0002] In the construction of hydraulic pressure water tunnels, when the caverns entering and exiting the mountain are shallowly buried, or the surrounding rock has developed cracks and poor integrity, adding steel linings becomes a necessary measure to ensure the safety of the project. The main function of the steel lining is to make the steel pipes, concrete linings and mountain rocks as steel linings bear the internal water pressure together, thereby improving the safety of the tunnel. After taking steel lining reinforcement, it can eliminate the internal water seepage caused by concrete cracks, effectively improve water delivery efficiency and reduce operating costs, eliminate the adverse consequences caused by internal water seepage, and ensure the stability of the mountain and avoid the instability of the tunnel inlet and outlet buildings.

[0003] However, the implementation of large-diameter steel lining construction in a narrow and confined space environment has always been a major challenge in the project. Past construction methods often rely on a large amount of manual operation and relatively simple mechanical assistance, lacking systematicity and efficiency. For example, in the transportation of steel pipes, relatively primitive and inefficient handling methods may be used, which is not only inefficient but also easy to cause damage to the steel pipes. In terms of adjusting the elevation axis and fixing the steel lining, it may rely on experience and rough tools, making it difficult to ensure accuracy and stability. The welding process may also be relatively traditional, resulting in unstable welding quality and low efficiency, while increasing safety risks in construction.

[0004] Traditional construction methods lack accurate measurement and planning, resulting in chaotic construction processes, serious interference during construction, and greatly reduced efficiency. A high proportion of manual operations makes the construction progress susceptible to human factors and it is difficult to ensure accuracy. Complex and cumbersome procedures and inefficient operation methods not only delay the construction period, but also increase costs. At the same time, there are deficiencies in safety measures during the construction process, which poses a greater safety threat to construction workers. Summary of the invention

[0005] The purpose of the present invention is to solve the problems existing in the construction of large-diameter steel linings in narrow and confined spaces, and to provide a large-diameter steel lining construction method in a narrow and confined space. The method reduces construction interference, improves construction efficiency, speeds up construction progress, reduces safety hazards and saves costs by optimizing the transportation and welding process in the steel pipe hole.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention provides a large-diameter steel lining construction method in a narrow confined space, comprising the following steps:

[0008] Step 1: Use the construction site measurement control network to lay out the axis and elevation of the steel pipe transportation track;

[0009] Step 2: According to the measurement and layout results, a track is installed on the tunnel floor, and the track extends axially from the designed mileage of the steel pipe to the outside of the tunnel entrance;

[0010] Step 3: Lift the steel pipe onto the track, make the steel wheel on the steel pipe cooperate with the track, and use the traction mechanism to pull the steel pipe along the track to the installation position in the hole;

[0011] Step 4: After the steel pipe is transported to the installation location, adjust the mileage and elevation of the steel pipe to the designed mileage and elevation;

[0012] Step 5: After the mileage and elevation of the steel pipe are adjusted to the correct position, the steel wheel is welded and fixed to the track, and the steel pipe is fixed through multiple anchor points evenly distributed along the circumference;

[0013] Step 6: Weld the circumferential weld of the steel pipe using a single-sided welding and double-sided forming welding process;

[0014] Step 7: After the steel pipe is welded, perform nondestructive testing on the weld;

[0015] Step 8: Patching and anti-corrosion of steel pipes.

[0016] As a preferred embodiment of the present invention, in step 1, a measurement control network is set up at the construction site, and a total station is used to perform measurement and construction control to accurately lay out the axis and elevation of the steel pipe transportation track.

[0017] As a preferred embodiment of the present invention, in step 2, two rails are arranged side by side and are installed and fixed by a rail base embedded in the concrete of the tunnel floor.

[0018] As a preferred embodiment of the present invention, the traction mechanism in step three includes a winch, a guide pulley and a steel strand, the steel strand is placed in the guide pulley, one end of the steel strand is wound around the winch, and the other end is connected to the steel pipe.

[0019] As a preferred embodiment of the present invention, when adjusting the elevation of the steel pipe in step four, multiple support plates are symmetrically welded on the steel pipe, and jacks are respectively set to support the support plates. The steel pipe is lifted up by adjusting multiple jacks at the same time to adjust the steel pipe to the designed elevation.

[0020] As a preferred embodiment of the present invention, in step five, after the steel pipe is adjusted to the designed elevation, the steel wheel is welded and fixed to the rail, and multiple anchor points are symmetrically arranged on the cross section of the steel pipe, and the threaded steel anchoring depth is not less than 1.5m.

[0021] As a preferred embodiment of the present invention, in step six, tack welding is first performed when welding the steel pipe. The tack weld should be located more than 30 mm from the end of the weld, have a length of more than 50 mm, a spacing of 100 to 400 mm, and a thickness not greater than 1 / 2 of the formal weld thickness and not greater than 8 mm.

[0022] As a preferred embodiment of the present invention, before welding the steel pipe in step 6, all scales, rust, oil stains and other debris within 50 to 100 mm on both sides of the intended welding surface and the groove should be removed, and welding can only be carried out after passing the inspection.

[0023] As a preferred embodiment of the present invention, nondestructive testing is performed 48 hours after the steel pipe welding is completed in step seven. The nondestructive testing adopts ultrasonic flaw detection, and the nondestructive flaw detection sampling rate of the steel pipe weld is 100%.

[0024] As a preferred embodiment of the present invention, the steel pipe patching anti-corrosion in step eight includes internal anti-corrosion and external anti-corrosion; the internal anti-corrosion adopts manual rolling of solvent-free epoxy anti-corrosion coating, the coating thickness is not less than 600μm, and the adhesion is not less than 10Mpa; the external anti-corrosion adopts manual rolling of solvent-free epoxy anti-corrosion coating, the coating thickness is not less than 1000μm, and the adhesion is not less than 10Mpa.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] The present invention adopts the in-tunnel traction method of track + steel wheel + winch, combined with precise steel pipe transportation track axis measurement and layout and jack fine-tuning of steel pipe elevation, which greatly improves construction efficiency, shortens construction period, and ensures high precision of steel pipe installation; through the application of non-disassembly steel wheels and optimized steel pipe fixing method, construction delays caused by complicated procedures are avoided and costs are effectively reduced; through the use of single-sided welding and double-sided forming welding technology, high efficiency is demonstrated in confined spaces, construction safety risks are reduced, and welding quality is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0028] Figure 1 It is a flow chart of the large diameter steel lining construction method in a narrow confined space of the present invention;

[0029] Figure 2 This is a schematic diagram of the steel pipe out-hole transportation in the present invention;

[0030] Figure 3 It is a schematic diagram of traction in a steel pipe hole in the present invention;

[0031] Figure 4 It is a cross-sectional schematic diagram of the steel pipe in the present invention located in the hole;

[0032] Figure 5 For the present invention Figure 4 A is an enlarged schematic diagram.

[0033] Marks and corresponding parts names in the attached drawings:

[0034] 1- winch, 2- guide pulley, 3- steel strand, 4- track, 5- steel pipe, 51- stiffening ring, 52- steel wheel, 6- flatbed transport vehicle, 7- truck crane, 8- rail base. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0037] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0038] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0039] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0040] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0041] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces), unless otherwise clearly and specifically defined.

[0042] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0043] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0044] Please refer to Figures 1 to 5 , a large-diameter steel lining construction method in a narrow confined space provided in an embodiment of the present application comprises the following steps:

[0045] Step 1: Use the construction site measurement control network to lay out the axis and elevation of the steel pipe transportation track;

[0046] Step 2: According to the measurement and layout results, a track 4 is installed on the tunnel floor, and the track 4 extends axially from the designed mileage of the steel pipe to the outside of the tunnel entrance;

[0047] Step 3: hoist the steel pipe 5 onto the track 4, and make the steel wheel 52 provided on the steel pipe 5 cooperate with the track 4, and use the traction mechanism to pull the steel pipe 5 along the track 4 to the installation position in the hole;

[0048] Step 4: After the steel pipe 5 is transported to the installation location, adjust the mileage and elevation of the steel pipe to the designed mileage and elevation;

[0049] Step 5: After the mileage and elevation of the steel pipe are adjusted to the desired position, the steel wheel 52 is welded and fixed to the track 4, and the steel pipe 5 is fixed by multiple anchor points evenly distributed along the circumference;

[0050] Step 6: Weld the circumferential weld of the steel pipe using a single-sided welding and double-sided forming welding process;

[0051] Step 7: After the steel pipe is welded, perform nondestructive testing on the weld;

[0052] Step 8: Patching and anti-corrosion of steel pipes.

[0053] In this embodiment, the in-tunnel traction method of track + steel wheel + winch is adopted, combined with precise measurement and layout of the steel pipe transportation track axis and fine-tuning of the steel pipe elevation by jack, which greatly improves the construction efficiency, shortens the construction period, and ensures the high precision of steel pipe installation; the application of non-disassembly steel wheels and optimized steel pipe fixing methods avoids construction delays caused by complex procedures and effectively reduces costs; the single-sided welding and double-sided forming welding process is adopted, which shows high efficiency in confined spaces, reduces construction safety risks, and significantly improves welding quality.

[0054] According to some embodiments of the present application, in step 1, a measurement control network is set up at the construction site, and a total station is used for measurement and construction control to accurately lay out the axis and elevation of the steel pipe transportation track. By laying out the axis and elevation of the steel pipe transportation track, preparations are made for the subsequent track installation, so that after the steel pipe is transported along the track to the installation location, its elevation does not deviate much from the design elevation, thereby reducing the time for adjusting the steel pipe elevation.

[0055] The function of the survey control network in this embodiment is to control the three-dimensional position (plane position and elevation) of the construction area. The survey control network is the basis for construction layout, project completion, building settlement observation, and future building reconstruction and expansion. The characteristics, accuracy, layout principles and layout forms of the survey control network must meet the requirements of the construction itself.

[0056] According to some embodiments of the present application, in the step 2, two rails 4 are arranged side by side and are fixed by a rail base 8 embedded in the tunnel floor concrete. By embedding the rail base 8 during the pouring of the tunnel floor concrete, the embedded position of the rail base 8 needs to be determined according to the axis and elevation of the steel pipe transport track laid out to ensure that after the rail 4 is installed on the rail base 8, its axis and elevation meet the requirements.

[0057] In this embodiment, the track 4 is made of 38kg / m steel rails and installed on the rail base 8 in the concrete of the water tunnel floor. The two tracks 4 are welded together using φ20 steel bars, and the steel bar spacing is 1.5m. The tunnel floor concrete is C25 reinforced concrete. Before pouring the floor, embedded dowel bars are connected to the rail base 8 to prevent subsequent track axis and elevation changes caused by pouring the floor.

[0058] According to some embodiments of the present application, the traction mechanism in step 3 includes a winch 1, a guide pulley 2 and a steel strand 3, wherein the steel strand 3 is placed in the guide pulley 2, one end of the steel strand 3 is wound around the winch 1, and the other end is connected to the steel pipe 5. When the steel pipe is transported in a tunnel, the steel pipe 5 is first hoisted onto the track 4 at the tunnel entrance, and a 10t winch 1, a guide pulley 2 and a steel strand 3 are arranged at an appropriate position in the tunnel, and then the winch 1 drives the steel strand 3 to be reeled, thereby using the steel strand 3 to pull the steel pipe 5 along the track 4 to the installation position.

[0059] It should be noted that in this embodiment, DN3200, Q345R steel pipe 5 is used, with a wall thickness of 20mm and a single section length of 4.0m. The steel pipe 5 has stiffening rings 51 on the outer circle near both ends, and two steel wheels 52 are symmetrically installed on each stiffening ring 51 near the bottom plate of the tunnel. When traction is carried out, the steel wheels 52 roll along the track 4. The steel pipe is transported to the tunnel entrance by a 20t flatbed transporter 6, and a 25t truck crane 7 is used to unload the steel pipe manually.

[0060] According to some embodiments of the present application, when adjusting the elevation of the steel pipe in step 4, multiple support plates are symmetrically welded on the steel pipe 5, and jacks are respectively provided to support the support plates, and the steel pipe 5 is lifted up by adjusting multiple jacks at the same time, so that the steel pipe 5 is adjusted to the designed elevation. By symmetrically arranging multiple jacks, it is convenient to lift up the steel pipe in a narrow space, thereby facilitating the adjustment of the elevation of the steel pipe.

[0061] Specifically, after the steel pipe 5 is transported to the installation position, the mileage of the steel pipe is adjusted to the designed mileage (±5mm), and then four support plates are symmetrically welded on the two stiffening rings 51 of the steel pipe 5. Four spiral jacks are placed under the support plates, and four people operate the jacks at the same time to lift the steel pipe 5 simultaneously and slowly, so that the steel pipe 5 is adjusted to the designed elevation (±2cm).

[0062] According to some embodiments of the present application, in step 5, after the steel pipe 5 is adjusted to the design elevation, the steel wheel 52 is welded and fixed to the track 4, and multiple anchor points are symmetrically set on the cross section of the steel pipe, and the anchor depth of the threaded steel is not less than 1.5m. By welding and fixing the steel wheel to the track, the steel wheel can be prevented from moving along the track; at the same time, by forming multiple anchor points symmetrically on the cross section of the steel pipe, the position of the steel pipe can be further fixed, ensuring that the position of the steel pipe remains unchanged during subsequent welding.

[0063] In this embodiment, after the steel pipe is adjusted to the design elevation, the steel wheel 52 is welded and fixed to the track 4. At the same time, 8 anchor points are symmetrically set on the cross section of the stiffening ring, and the anchor depth of φ28 threaded steel is not less than 1.5m. Of course, according to the actual situation, anchor rods can be set in advance on the tunnel wall according to the distribution position. When fixing the steel pipe, it is only necessary to use steel bars to weld the anchor rods and the steel pipe, which can further improve the construction efficiency in narrow spaces.

[0064] According to some embodiments of the present application, before welding the steel pipe in step six, all oxide scales, rust, oil stains and other debris within 50 to 100 mm on all welded surfaces and both sides of the groove should be cleaned up, and the welding slag on the surface of each layer of welding metal should be carefully cleaned up. All welding slag should be cleaned up before welding the next layer, and welding can only be carried out after inspection and approval.

[0065] According to some embodiments of the present application, in the step six, tack welding is first performed when welding the steel pipe. The position of the tack weld should be more than 30 mm away from the end of the weld, its length should be more than 50 mm, the spacing should be 100-400 mm, and the thickness should not be greater than 1 / 2 of the thickness of the formal weld and should not be greater than 8 mm. The spot welding electrode uses the same welding rod as the interface welding electrode. The spot welding should be performed symmetrically, and the weld height should be consistent with the thickness of the first layer of weld. The arc starting and arc breaking of the tack welding should be performed within the groove. The joints between layers of multi-layer welding should be staggered. Each weld should be welded continuously at one time. When welding is interrupted for some reason, anti-cracking measures should be taken. Before re-welding, the surface should be cleaned and confirmed to be free of cracks before welding can be continued according to the original process.

[0066] Positioning welds play an important role in welding construction. The distance between the positioning weld and the end of the weld is set to be more than 30mm, which can avoid the positioning weld from having an adverse effect on the quality of the starting and ending ends of the formal weld, and ensure the continuity and stability of the formal weld; a length of more than 50mm helps to provide sufficient connection strength and stability, ensuring that the workpiece will not be displaced significantly during the subsequent welding process; a spacing of 100 to 400mm can ensure the positioning effect while avoiding the positioning welds being too dense and affecting the quality of the formal weld; the thickness is not more than 1 / 2 of the thickness of the formal weld and not more than 8mm, in order to prevent the positioning weld from being too thick and causing large welding stress and deformation during subsequent welding, affecting the quality of the overall welded structure.

[0067] According to some embodiments of the present application, nondestructive testing is performed 48 hours after the steel pipe welding is completed in step 7. The nondestructive testing adopts ultrasonic flaw detection, and the nondestructive flaw detection sampling rate of the steel pipe weld is 100%. Nondestructive testing personnel should undergo professional training, pass the national professional department examination, and obtain a nondestructive testing qualification certificate. The assessment of weld quality should be performed by nondestructive testing personnel of level II or above.

[0068] According to some embodiments of the present application, the steel pipe patching anti-corrosion in step eight includes internal anti-corrosion and external anti-corrosion; the internal anti-corrosion adopts manual rolling of solvent-free epoxy anti-corrosion coating, the coating thickness is not less than 600μm, and the adhesion is not less than 10Mpa; the external anti-corrosion adopts manual rolling of solvent-free epoxy anti-corrosion coating, the coating thickness is not less than 1000μm, and the adhesion is not less than 10Mpa.

[0069] When applying manually, a designated person shall prepare the paint, mix the base material and curing agent of the primer evenly (the temperature of the base material and curing agent should be maintained at 0-50℃ so that the paint can be evenly mixed), and mix according to the method and proportion recommended in the paint manual. The specific requirements are as follows: proportion: YM118 (A): YM118 (B) = 100: 18-25. During the mixing process, attention must be paid to the base material on the barrel wall and the bottom of the barrel. This process should not exceed 3 minutes. Try to avoid mixing of gas during the mixing process.

[0070] Use a sponge roller or scraper to apply the paint after the base material and curing agent have been evenly mixed. The paint needs to be applied in multiple layers and multiple layers. During the process, the interval between the coatings should be controlled according to the paint instructions. The coating thickness should be measured before each layer is applied and the corresponding test records should be made. Apply the paint 3 to 4 times on the inner wall. After the coating is completed, wait for the coating to dry on the surface (dry on the surface means that the anti-corrosion layer is not sticky when touched by a finger, or it is sticky but no paint sticks to the finger).

[0071] According to some embodiments of the present application, after the steel pipe joints are patched and anti-corrosion is completed, concrete backfill is poured between the outer wall of the steel pipe and the tunnel. After the concrete is filled, the steel pipe is firmly wrapped in the concrete, so that the steel pipe, backfill concrete, initial support of the tunnel and mountain rock bear the internal water pressure together, thereby improving the safety of the tunnel. During the backfilling, concrete pouring and backfill grouting are performed in 3 to 4 compartments.

[0072] In the present application, measuring instruments are used for precise layout before track installation, and the track installation position and elevation are determined according to the steel pipe installation elevation and axis. The steel pipe is pulled to the installation position using track + steel wheel + winch. After the steel pipe is pulled to the installation position, a spiral jack is used to fine-tune the steel pipe elevation before welding and fixing it, which greatly improves the construction efficiency and shortens the construction period. At the same time, it ensures the high precision of steel pipe installation and avoids construction workers from working in confined spaces for a long time.

[0073] In this application, a non-disassembly steel wheel is welded to the steel pipe stiffening ring. After the steel pipe is transported to the installation location and the elevation axis is adjusted, the steel wheel is welded to the track to fix the steel pipe. At the same time, combined with the setting of multiple anchor points, delays in construction caused by complex processes such as steel wheel disassembly and steel pipe fixing in a confined space are avoided, effectively reducing costs.

[0074] The water diversion tunnel in this application is 3.7m wide and the outer diameter of the steel pipe is 3.4m (stiffening ring is 10cm). After the steel pipe enters the tunnel, welding operations cannot be performed on the outside of the steel pipe due to limited space. Therefore, a single-sided welding and double-sided forming welding process is adopted, which shows high efficiency in confined space, reduces construction safety risks, and significantly improves welding quality.

[0075] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for constructing a large-diameter steel lining in a narrow confined space, characterized in that: The following steps are involved: Step 1: Use the construction site measurement control network to lay out the axis and elevation of the steel pipe transportation track; Step 2: According to the measurement and layout results, a track is installed on the tunnel floor, and the track extends axially from the designed mileage of the steel pipe to the outside of the tunnel entrance; Step 3: Lift the steel pipe onto the track, make the steel wheel on the steel pipe cooperate with the track, and use the traction mechanism to pull the steel pipe along the track to the installation position in the hole; Step 4: After the steel pipe is transported to the installation location, adjust the mileage and elevation of the steel pipe to the designed mileage and elevation; Step 5: After the mileage and elevation of the steel pipe are adjusted to the correct position, the steel wheel is welded and fixed to the track, and the steel pipe is fixed through multiple anchor points evenly distributed along the circumference; Step 6: Weld the circumferential weld of the steel pipe using a single-sided welding and double-sided forming welding process; Step 7: After the steel pipe is welded, perform nondestructive testing on the weld; Step 8: Patching and anti-corrosion of steel pipes.

2. The method for constructing a large-diameter steel lining in a narrow confined space according to claim 1 is characterized in that: In the step 1, a measurement control network is set up at the construction site, and a total station is used to perform measurement and construction control to accurately lay out the axis and elevation of the steel pipe transportation track.

3. The method for constructing a large-diameter steel lining in a narrow confined space according to claim 1, characterized in that: In the step 2, two rails are arranged side by side and are installed and fixed by a rail base embedded in the concrete of the tunnel floor.

4. The method for constructing a large diameter steel lining in a narrow confined space according to claim 1, characterized in that: The traction mechanism in step three includes a winch, a guide pulley and a steel strand, wherein the steel strand is placed in the guide pulley, one end of the steel strand is wound around the winch, and the other end is connected to a steel pipe.

5. The method for constructing a large diameter steel lining in a narrow confined space according to claim 1, characterized in that: When adjusting the elevation of the steel pipe in step 4, multiple support plates are symmetrically welded on the steel pipe, and jacks are respectively set to support the support plates. The steel pipe is lifted up by adjusting multiple jacks at the same time to adjust the steel pipe to the designed elevation.

6. The method for constructing a large diameter steel lining in a narrow confined space according to claim 1, characterized in that: In the step 5, after the steel pipe is adjusted to the designed elevation, the steel wheel is welded and fixed to the rail. At the same time, multiple anchor points are symmetrically set on the cross section of the steel pipe, and the threaded steel anchoring depth is not less than 1.5m.

7. The method for constructing a large diameter steel lining in a narrow confined space according to claim 1, characterized in that: When welding the steel pipe in step six, positioning welding is first performed. The position of the positioning weld should be more than 30 mm away from the end of the weld, its length should be more than 50 mm, the spacing should be 100-400 mm, and the thickness should not be greater than 1 / 2 of the formal weld thickness and not greater than 8 mm.

8. The method for constructing a large diameter steel lining in a narrow confined space according to claim 7, characterized in that: Before welding the steel pipe in step 6, all oxide scales, rust, oil stains and other debris within 50 to 100 mm on both sides of the intended welding surface and the groove should be removed, and welding can only be carried out after passing the inspection.

9. The method for constructing a large diameter steel lining in a narrow confined space according to claim 1, characterized in that: In the step 7, non-destructive testing is performed 48 hours after the steel pipe welding is completed. The non-destructive testing adopts ultrasonic flaw detection, and the non-destructive flaw detection sampling rate of the steel pipe weld is 100%.

10. The method for constructing a large diameter steel lining in a narrow confined space according to claim 1, characterized in that: The steel pipe patching anti-corrosion in step eight includes internal anti-corrosion and external anti-corrosion; the internal anti-corrosion adopts manual rolling of solvent-free epoxy anti-corrosion paint, the coating thickness is not less than 600μm, and the adhesion is not less than 10Mpa; the external anti-corrosion adopts manual rolling of solvent-free epoxy anti-corrosion paint, the coating thickness is not less than 1000μm, and the adhesion is not less than 10Mpa.

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