Long tunnel rapid construction method using short steps for full cross section

Abstract

The application discloses a kind of long big tunnel utilizes short step to carry out the rapid construction method of full section, comprising the following steps: S1: by excavator, site is simultaneously flattened, and the wind pipe, water pipe of excavation face is installed in place, and the illumination equipment of face is normal;S2: the excavation height of upper step is 7-8 meters, the excavation height of lower step is 3-3.5 meters, and upper and lower steps are staggered for 8-12 meters, and lower step is staggered 3-5 meters on left and right sides, and upper and lower steps are synchronously advanced;S3: by excavator, hole residue of upper step is scooped to lower step, then residue is discharged in lower step;S4: after section inspection is qualified, according to the order of lower step first and then upper step, initial spraying closure is sequentially completed;S5: after initial spraying is completed, upper and lower steps are simultaneously constructed, and finally, according to the order of lower step first and then upper step, secondary spraying concrete closure is sequentially completed.Not only the tunnel safety management level is improved, and safety risk is reduced, but also the tunnel construction efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of initial support for tunnel construction, and in particular relates to a method for rapidly constructing a long tunnel across its entire section by using short steps. Background Art

[0002] A long tunnel is one with a large cross-section. The Bazi Tunnel is 5,471 meters long, with a maximum burial depth of approximately 210 meters and a designed longitudinal slope of 30‰, making it a large, long and cross-section tunnel. The tunnel has 100 meters of Grade III surrounding rock, accounting for 1.8%, 4,750 meters of Grade IV, accounting for 86.8%, and 583 meters of Grade V, accounting for 11.4%. The tunnel faces dangerous rockfall at the entrance, and the tunnel traverses gently dipping strata, weak sections, and unfavorable geological conditions such as the axis of a syncline. If traditional long-step excavation methods were used, the upper steps would each be over 30 meters long, intersecting and interfering with the lower steps and invert construction, leading to delayed invert progress and excessive safety step distances. Summary of the Invention

[0003] The present invention intends to provide a method for rapid construction of a long tunnel using short steps for the entire section, which not only improves the tunnel safety management level and reduces safety risks, but also improves tunnel construction efficiency.

[0004] To this end, the technical solution adopted by the present invention is: a method for rapid construction of a long tunnel using short steps for full section, comprising the following steps:

[0005] S1: Construction preparation;

[0006] The site was leveled using an excavator, and the air ducts and water pipes on the excavated face were installed in place. The lighting equipment on the face was functioning properly.

[0007] S2: excavation of upper and lower steps simultaneously;

[0008] The excavation height of the upper step is 7-8 meters, and the excavation height of the lower step is 3-3.5 meters. The upper and lower steps are staggered by 8-12 meters, and the left and right sides of the lower step are staggered by 3-5 meters. The upper and lower steps are advanced synchronously, with each cycle advancing 3 meters, and one arch frame is erected every meter.

[0009] S3: slag is discharged simultaneously on the upper and lower steps;

[0010] The excavator removes the slag from the upper step to the lower step, and then removes the slag together on the lower step. During the slag removal process, some slag is reserved for building passages for the upper and lower steps. At the same time, the excavator clears dangers and under-excavates the tunnel face and arch ring of the upper step. When removing dangerous rocks from the tunnel face, the excavator controls the tunnel face slope ratio to ensure that the slope ratio requirement is less than 1:0.1.

[0011] S4: continuous initial spraying of up and down steps;

[0012] After the cross-section inspection is qualified, the wet spraying manipulator is stopped on the upper and lower step channels, and the initial spraying and sealing is completed in the order of first going down the step and then going up the step;

[0013] S5: Primary support for both upper and lower steps;

[0014] After the initial spraying is completed, the upper and lower steps are erected at the same time, and then the construction of the advance small guide tube, anchor rod and steel mesh is carried out at the same time. Finally, the wet spraying robot is stopped on the upper and lower step passages, and the re-spraying concrete sealing is completed in the order of first the lower step and then the upper step.

[0015] As a preferred embodiment of the above scheme, excavation in S2 includes drilling, charging, blasting, ventilation, smoke exhaust and dust reduction, and when excavating on the upper steps, an excavation platform with three steps is equipped.

[0016] It is further preferred that in S5, the construction of the stand, the advance small conduit, the anchor rod and the steel mesh is carried out simultaneously on the upper and lower steps, and the construction of the advance small conduit and the anchor rod is achieved in conjunction with the excavation stand with three steps.

[0017] Further preferably, when erecting the arch, the joints at the lower end of the arch are each provided with a protective device, the protective device comprising a top plate, side plates, and a bottom plate, the top plate and the side plates, and the side plates and the bottom plate being hinged, the top plate, the side plates, and the bottom plate being able to be combined to form a U-shaped structure that fits the arch joint, the top plate having a rectangular notch at one end away from the joint that fits the arch, the side plates having a rib in the middle for abutting the side of the arch joint, and the bottom plate having a pull ring at one end away from the joint. When in use, the top plate, the side plates, and the bottom plate can be combined to form a U-shaped structure that is then directly snapped onto the arch joint.

[0018] Further preferably, the side panels are hinged to the left and right sides respectively with a first wing panel and a second wing panel blocking the corresponding side surfaces of the joint.

[0019] Further preferably, the rib is vertically arranged in the middle of the side plate and both upper and lower ends are arranged as inclined surfaces, and the abutting surface of the rib is provided with an arc-shaped protrusion for reducing friction.

[0020] Further preferably, the method further comprises the following steps:

[0021] S6: Invert construction;

[0022] After the upper and lower steps are constructed 40-50 meters forward, the construction of the invert arch begins. During the construction of the invert arch, a trestle is built above the invert arch construction section. The invert arch construction includes invert arch excavation, invert arch slag removal, invert arch initial spraying, invert arch initial support, invert arch filling and invert arch secondary lining construction;

[0023] S7: Tunnel secondary lining construction;

[0024] After 50-70 meters of invert construction, the secondary lining construction of the tunnel begins using the secondary lining trolley.

[0025] It is further preferred that when the upper and lower steps are slag-discharging, the invert arch reinforcement binding, filling and secondary lining casting construction are carried out; when the upper and lower steps are initially sprayed or re-sprayed, the invert arch, filling and secondary lining casting construction are carried out; when the upper and lower steps are drilled, the arch frame is installed and the anchor rods are constructed, the invert arch excavation, invert arch, filling and secondary lining casting construction are carried out.

[0026] More preferably, the dimensions of the up and down stair passage built in S3 are 15 meters in length and 6 meters in width.

[0027] It is further preferred that when concrete spraying is being carried out on the upper and lower steps, the excavation platforms are transported to the rear of the upper and lower step passages by a loader.

[0028] Beneficial effects of the present invention:

[0029] 1) The two-step method is used for construction of surrounding rock of different grades to reduce the time of construction method conversion when the surrounding rock changes; and the length of the upper and lower steps is consistent, which facilitates the flexible conversion of equipment and is conducive to the effectiveness of the equipment, thus facilitating the implementation of full-section construction using the step method.

[0030] 2) Drilling and blasting are performed simultaneously on the upper and lower steps. After blasting, the upper and lower steps are staggered 8-12 meters apart. The excavator is used to scrape the slag from the upper step to the lower step, and then the slag is removed together on the lower step. After the removal of the slag, the upper and lower steps are erected and operated in parallel. The upper and lower steps are sprayed simultaneously. This allows for step-by-step flow operations and full-section construction, which not only improves tunnel safety management and reduces safety risks, but also increases tunnel construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a longitudinal section view of the short step during construction of the present invention.

[0032] Figure 2 It is a cross-sectional view of the short step in the present invention.

[0033] Figure 3 It is a longitudinal section view of the present invention during full-section construction.

[0034] Figure 4 It is an expanded view of the protection device in the present invention.

[0035] Figure 5 It is a structural schematic diagram of the protection device in the present invention.

[0036] Figure 6 This is an expanded view of the protective device of the present invention with wing panels added.

[0037] Figure 7Structure diagram of wing plate for protection device in the application.

[0038] Figure 8 Exploded view of protection device in the application (without rib plate).

[0039] Figure 9 Structure diagram of rib plate for protection device in the application.

[0040] Figure 10 Assembly front view of protection device in the application.

[0041] Figure 11 Use diagram of protection device in the application.

[0042] Figure 12 Cross-sectional view of simultaneous anchor drilling at upper and lower steps.

[0043] Figure 13 Tunnel construction longitudinal section view at upper and lower steps during slagging.

[0044] Figure 14 Tunnel construction longitudinal section view at upper and lower steps during initial support shotcrete.

[0045] Figure 15 Tunnel construction longitudinal section view at upper and lower steps during initial support without shotcrete. DETAILED DESCRIPTION

[0046] The application will be further described below by examples and in conjunction with the drawings:

[0047] As shown in the drawings, a long tunnel uses short steps for full cross-section rapid construction method, mainly including the following steps: Figures 1-15

[0048] First step: construction preparation. Level the site with an excavator to ensure a flat and solid ground without the risk of equipment overturning, and install the wind pipe and water pipe on the excavation surface, and ensure that the lighting equipment on the surface is normal.

[0049] Second step: simultaneous excavation of upper and lower steps. The excavation height of the upper step is 7-8 meters, and the excavation height of the lower step is 3-3.5 meters. The upper step is in front, and the lower step is behind, and the upper and lower steps are staggered by 8-12 meters, and the left and right sides of the lower step are staggered by 3-5 meters. The upper and lower steps are pushed forward synchronously, with a cycle of 3m per time and 1 arch frame per meter. Specifically, it includes simultaneous drilling construction of upper and lower steps, and simultaneous charging, blasting, ventilation, smoke and dust removal of upper and lower steps. During drilling construction, 1 arch frame is erected per meter with a cycle of 3m per time, and 14 air guns are provided for the upper step and 4 air guns are provided for the lower step. In order to facilitate the drilling construction and charging of the upper step, an excavation rack with three steps is provided.​

[0050] Step 3: Simultaneous slag removal on the upper and lower steps. The excavator removes the slag from the upper step to the lower step, where it is then removed simultaneously. During the slag removal process, some slag is reserved for constructing a passageway between the upper and lower steps. The passageway is 15 meters long and 6 meters wide, facilitating the operation of large-scale machinery. Simultaneously, the excavator clears hazards and addresses under-excavation on the upper step's face and arch ring. While clearing dangerous rock from the face, the excavator controls the face slope to ensure it is less than 1:0.1 to prevent inverted overhangs.

[0051] Step 4: Continuous initial spraying of the upper and lower steps. After the cross-section inspection is qualified, the wet spraying robot will stop on the upper and lower step channels and complete the initial spraying and sealing in the order of first going down the step and then going up the step.

[0052] Step 5: Initial support of the upper and lower steps simultaneously. This includes the construction of the frame, advance small guide tubes, anchor rods, and re-spraying concrete.

[0053] While the initial spraying is in progress, the loader prepares to transport the platform and arch. After the initial spraying is complete, the loader transports the platform and arch to the upper and lower steps, with the upper and lower steps working simultaneously and in parallel. During erection, each arch is equipped with a protective device at the lower joint. This device protects the steel arch joints, minimizing damage during lowering the steps or inverting the arch, thus facilitating the connection between the two arches.

[0054] The protective device is mainly composed of a top plate A, a side plate B and a bottom plate C. The top plate A and the side plate B, as well as the side plate B and the bottom plate C are all hinged, and a rotatable shaft can be used. The top plate A, the side plate B and the bottom plate C can be combined to form a 匚-shaped structure that fits the arch frame joint. A rectangular opening that fits the arch frame is provided at one end of the top plate A away from the connection. When in use, the arch frame is inserted into the opening of the top plate A, and the side plates B and the bottom plate C are fitted with the arch frame joint in turn, and sand and gravel are used to fill the outside of the 匚-shaped structural protective device formed. Since the protective device can be combined to form a 匚-shaped structure that fits the arch frame joint, it can replace the transmission concrete pads as the foundation of the bottom of the steel arch frame, thereby reducing the number of concrete pads used and thus reducing costs.

[0055] Since the opening of the top plate A is tightly fitted with the arch frame, and a rib 1 is provided in the middle of the side plate B for abutting against the side of the arch frame joint for limiting position, the strength of the overall structure is enhanced.

[0056] A pull ring 2 is provided at one end of the base plate C, away from the connection. The pull ring 2 can be a hole set in the base plate C, or a circular ring installed on the bottom surface of the base plate C. During the construction of the lower step or invert arch, the protective device needs to be leaked out during blasting or slag removal. The pull ring 2 can be used to quickly remove the protective device.

[0057] In order to make the protective device fit with the arch frame, the top plate A, side plate B and bottom plate C are rectangular steel plates, and the length and width of the top plate A and bottom plate C match the length and width of the arch frame joint. The height of the side plate B is higher than the thickness of the arch frame joint, so that after the protection is installed, space can be left for the arch frame joint to connect with the next joint.

[0058] As needed, the left and right sides of the side panel B can also be hinged with a first wing panel D and a second wing panel E respectively, which block the corresponding sides of the joint to protect the two sides of the arch joint.

[0059] Preferably, the rib 1 is vertically arranged in the middle of the side panel B and has inclined surfaces at both ends to facilitate the covering of the top panels A and B. At the same time, the abutting surface of the rib 1 is provided with an arc-shaped protrusion to reduce friction, avoid additional damage to the abutting surface of the joint, and facilitate the quick removal of the protective device.

[0060] After the erection of the scaffolding was completed, the construction of the small lead pipes, anchor rods, and steel mesh for the upper and lower steps was carried out simultaneously. The construction of the small lead pipes and anchor rods for the upper step was carried out by excavating the scaffolding. Forty small lead pipes were installed for the upper step, each 4.5 meters long, and 45 anchor rods were installed for the upper step, with 10 air guns deployed. For 25 anchor rods for the lower step, with two air guns deployed.

[0061] After the arch installation and advance support construction are completed, the re-spraying concrete operation is immediately carried out, and each cycle of spraying concrete is 45m 3 A wet spraying robot was used on site and was parked on the upper and lower steps. The sprayed concrete was sealed in the order of descending the steps first and then ascending them.

[0062] Step 6: Invert construction. Construction of the invert begins 40-50 meters after the upper and lower steps have been constructed. During invert construction, a trestle is built above the invert construction section. Invert construction includes invert excavation, invert slag removal, initial injection, initial support, filling, and secondary lining.

[0063] Step 7: Secondary lining construction of the tunnel. After the invert arch is constructed for 50-70 meters, the secondary lining trolley is used to start the secondary lining construction of the tunnel.

[0064] During the entire construction process, in order to further ensure safe construction, when the upper and lower steps are discharging slag, the slag trucks frequently go back and forth on the trestle, so during this period, the arch construction area is mainly used for steel bar binding, filling and secondary lining construction. Figure 13 When the upper and lower steps are initially sprayed or re-sprayed, the amount of sprayed concrete used in each cycle is small and the time for each truck of sprayed concrete is long, so the utilization rate of the trestle is low. All construction processes except the invert arch excavation can be carried out simultaneously during the construction process, such as Figure 14As shown. When drilling up and down the steps, installing arches, anchor rod construction, the trestle is basically not used, this period is the golden construction period, all processes can be constructed, inverted arch excavation construction can be carried out in this golden construction period, such as Figure 15 As shown.

Claims

1. A method for rapid construction of a long tunnel using short steps for full-section construction, characterized in that: It includes the following steps: S1: Construction preparation; Level the site with an excavator. Meanwhile, install the air ducts and water pipes at the excavation face, and ensure that the lighting equipment at the face is normal. S2: Excavate the upper and lower benches simultaneously. The excavation height of the upper bench is 7 - 8 meters, and the excavation height of the lower bench is 3 - 3.5 meters. The upper and lower benches are staggered by 8 - 12 meters, and the left and right sides of the lower bench are staggered by 3 - 5 meters. The upper and lower benches are advanced synchronously, with a cyclic advance of 3m each time, and 1 arch frame is erected per meter. S3: Muck out from the upper and lower benches simultaneously. Use an excavator to rake the muck from the upper bench to the lower bench, and then muck out together from the lower bench. During the raking process, reserve part of the muck for building the passage between the upper and lower benches. Meanwhile, the excavator performs danger removal and under-excavation treatment on the upper bench face and arch ring. When clearing the dangerous rocks at the face, the excavator controls the slope ratio of the face to ensure that the slope ratio requirement is less than 1:0.

1. S4: Conduct continuous initial spraying on the upper and lower benches. After the section inspection is qualified, stop the wet shotcreting manipulator on the passage between the upper and lower benches, and complete the initial spraying and sealing in sequence, starting from the lower bench and then the upper bench. S5: Conduct initial support on the upper and lower benches simultaneously. After the initial spraying is completed, erect the frames on the upper and lower benches simultaneously, and then conduct the construction of advance small ducts, anchor bolts, and wire mesh sheets simultaneously. Finally, stop the wet shotcreting manipulator on the passage between the upper and lower benches, and complete the re-spraying of concrete and sealing in sequence, starting from the lower bench and then the upper bench.

2. The method for rapid construction of a long tunnel using short steps across the entire section according to claim 1, characterized in that: In S2, the excavation includes drilling, charging, blasting, ventilation, smoke exhaust, and dust reduction. When excavating the upper bench, an excavation bench with three levels is equipped.

3. The method for rapid construction of a long tunnel using short steps for full-section construction according to claim 1, characterized in that: In S5, during the construction of erecting the frames, advance small ducts, anchor bolts, and wire mesh sheets, they are all carried out simultaneously on the upper and lower benches, and the construction of advance small ducts and anchor bolts is realized in cooperation with an excavation bench with three levels.

4. The method for rapid construction of a long tunnel using short steps for full-section construction according to claim 1, characterized in that: When erecting the frames, protective devices are provided at the joints at the lower ends of the arch frames. The protective devices include a top plate (A), side plates (B), and a bottom plate (C). The top plate (A) and the side plates (B) are hinged, and the side plates (B) and the bottom plate (C) are also hinged. The top plate (A), side plates (B), and bottom plate (C) can enclose into a U-shaped structure that fits the arch frame joint. A rectangular notch for cooperating with the arch frame is provided at one end of the top plate (A) away from the connection. A rib plate (1) is provided in the middle of the side plate (B) for abutting against the side of the arch frame joint. A pull ring (2) is provided at one end of the bottom plate (C) away from the connection.

5. The method for rapid construction of a long tunnel using short steps for full-section construction according to claim 4, characterized in that: On the left and right of the side plate (B), a first wing plate (D) and a second wing plate (E) that block the corresponding sides of the joint are respectively hinged.

6. The method for rapid construction of a long tunnel using short steps across the entire section according to claim 4, characterized in that: The rib plate (1) is vertically arranged in the middle of the side plate, and both the upper and lower ends are provided with inclined surfaces. An arc-shaped protrusion for reducing friction is provided on the abutting surface of the rib plate (1).

7. The method for rapid construction of a long tunnel using short steps for full section construction according to claim 1, characterized in that: It also includes the following steps: S6: Invert construction; Start the invert construction after the upper and lower benches have advanced 40 - 50 meters forward. When conducting the invert construction, a trestle is built above the invert construction section. The invert construction includes invert excavation, invert muck out, invert initial spraying, invert initial support, invert filling, and invert secondary lining construction. S7: Tunnel secondary lining construction; After the invert construction has advanced 50 - 70 meters, start the tunnel secondary lining construction with a secondary lining trolley.

8. The method for rapid construction of a long tunnel using short steps for full-section construction according to claim 7, characterized in that: When the slag is discharged from the upper and lower steps, the invert arch reinforcement binding, filling and secondary lining casting construction are carried out; when the upper and lower steps are initially sprayed or re-sprayed, the invert arch, filling and secondary lining casting construction are carried out; when the upper and lower steps are drilled, the arch frame and anchor rods are installed, the invert arch excavation, invert arch, filling and secondary lining casting construction are carried out.

9. The method for rapid construction of a long tunnel using short steps for full-section construction according to claim 1, characterized in that: The dimensions of the up and down stair passage built in S3 are 15 meters long and 6 meters wide.

10. The method for rapid construction of a long tunnel using short steps for full-section construction according to claim 2 or 3, characterized in that: When concrete spraying is being carried out on the upper and lower steps, the excavation platforms are transported to the rear of the upper and lower step passages by loaders.

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