WO2023061002A1 - 一种大断面隧道施工方法及支护结构 - Google Patents

一种大断面隧道施工方法及支护结构 Download PDF

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Publication number
WO2023061002A1
WO2023061002A1 PCT/CN2022/109414 CN2022109414W WO2023061002A1 WO 2023061002 A1 WO2023061002 A1 WO 2023061002A1 CN 2022109414 W CN2022109414 W CN 2022109414W WO 2023061002 A1 WO2023061002 A1 WO 2023061002A1
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tunnel
tunnels
section
section tunnel
constructed
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PCT/CN2022/109414
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English (en)
French (fr)
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高波
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中建三局第一建设工程有限责任公司
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Publication of WO2023061002A1 publication Critical patent/WO2023061002A1/zh

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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/04—Lining with building materials
    • E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/14—Lining predominantly with metal
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/38—Waterproofing; Heat insulating; Soundproofing; Electric insulating
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
    • E21D9/001—Improving soil or rock, e.g. by freezing; Injections

Definitions

  • the invention relates to the technical field of roadbed construction, in particular to a large-section tunnel construction method and a supporting structure.
  • the construction of large-section tunnels in related technologies is basically a construction method of step-by-step excavation combined with step-by-step lining, or a step-by-step excavation combined with the overall construction method.
  • the lining construction method divides a large-section tunnel into several small-section tunnels and excavates them step by step.
  • This construction method needs to set up more temporary supports, which only play a temporary stabilizing role and need to be removed later, resulting in huge waste, affecting the efficiency of on-site construction operations, and prolonging the construction period.
  • the present application proposes a large-section tunnel construction method, which solves the problem of low on-site construction efficiency caused by adopting the large-section tunnel construction method in the related art.
  • the large-section tunnel construction method of the present invention comprises:
  • Step S1 excavating multiple advance tunnels at intervals along the circumferential direction of the large-section tunnel to be constructed
  • Step S2 reinforcing the preceding tunnel
  • Step S3 excavating a subsequent tunnel between multiple preceding tunnels
  • Step S4 reinforcing the backward tunnel, and connecting the backward tunnel with the preceding tunnel to form the initial support structure of the large-section tunnel to be constructed;
  • Step S5 excavating the rock mass within the support range of the initial support structure to construct a large-section tunnel.
  • step S2 includes:
  • Step S21 setting positioning ribs on the wall of the preceding tunnel
  • Step S22 setting the advance support reinforcement in the advance tunnel, and connecting the advance support reinforcement with the positioning reinforcement
  • Step S23 pouring concrete into the preceding tunnel.
  • positioning bars are set in the leading tunnel to ensure the installation accuracy of the supporting steel bars in advance, so as to ensure the supporting effect of the initial supporting structure;
  • a reinforced concrete structure is formed to further improve the supporting effect of the primary support structure.
  • step S4 includes:
  • Step S41 performing roughening treatment on the concrete at the junction of the preceding tunnel and the following tunnel, so that the positioning ribs are partially located in the following tunnel;
  • Step S42 setting the rear support reinforcement in the rear tunnel, and connecting the rear support reinforcement with the positioning reinforcement
  • Step S43 pouring concrete into the backward tunnel.
  • the positioning bars are partially located in the following tunnel, which facilitates the binding and fixing of the rear supporting steel bars and the positioning bars, but also makes the handover
  • the leading tunnel at the position is formed with a rough surface, which is convenient for the close connection of the pouring concrete of the leading tunnel and the following tunnel, and improves the supporting effect of the primary support structure.
  • step S21 includes: according to the position of the steel bars of the primary support structure of the large-section tunnel to be constructed, setting out stakeout positioning points on the wall of the preceding tunnel, and setting up positioning ribs at the stakeout positioning points.
  • the positioning ribs are used for the installation and positioning of the primary support structure, thereby ensuring that the steel bars of the primary support structure can be installed in the tunnel walls of the preceding tunnel and the following tunnel according to the preset position, thereby ensuring that the primary support structure Effective support for large-section tunnels to ensure that the subsequent one-time excavation of large-section tunnels can be successfully implemented.
  • step S5 includes:
  • Step S51 whether the step distance meets the requirements of the working space
  • Step S52 performing secondary lining operation.
  • the tunnel can be further reinforced through the secondary lining operation to avoid the problem of collapse after the section is hollowed out, thereby meeting the construction design requirements of the tunnel and the requirements of on-site safe construction.
  • step S5 includes:
  • Step S51 whether the step distance meets the requirements of the working space
  • Step S52 whether the initial support structure can meet the force requirements
  • step S5 further includes step S53 of performing decoration, and step S53 is after step S52.
  • the decoration work can make the tunnel more beautiful, so as to meet the design requirements of its appearance quality. Thus ensuring that it can be put into use normally in the later stage.
  • Step S21 includes:
  • Step S41 includes:
  • the release agent can also be painted on the surface. After the excavation of the tunnel is completed, the backing board can be directly removed as a whole, which further improves the construction efficiency, and the removed backing board can be recycled and reused. Reduced construction costs.
  • Embossed lines can be set on the contact end surface of the backing plate and the preceding tunnel, so that after the backing plate is dismantled and chiseled off, the leading tunnel will form a rough surface on the concrete surface at the junction, and there is no need to gouging it again.
  • step S212 includes:
  • a steel plate is arranged at one end of the positioning rib, and after the concrete is poured in the tunnel ahead, the steel plate is pre-embedded in the preceding tunnel, and after the concrete is poured in the subsequent tunnel, the positioning rib part is pre-embedded in the subsequent tunnel, which improves the initial Structural strength of the supporting structure.
  • the steel plate can also limit the displacement of the positioning ribs, avoiding the displacement or inclination of the positioning ribs on the backing plate, and ensuring the installation accuracy of the positioning ribs.
  • the supporting steel bars in advance can be directly welded with the steel plate to realize the indirect connection with the positioning bars, which improves the efficiency of welding construction.
  • a large-section tunnel construction method provided by the present invention has at least the following beneficial effects:
  • the subsequent tunnel and the preceding tunnel are connected to form a large section to be constructed
  • the rock mass within the support range of the initial support structure is excavated to construct a large-section tunnel.
  • the large-section tunnel construction method adopted in this application does not need to set up and remove temporary support in the large-section tunnel, which improves the construction efficiency and reduces the workload of on-site staff. Risks of on-site construction work and construction costs.
  • this application adopts the method of first supporting and then excavating, which makes the construction safer.
  • the present invention also proposes a large-section tunnel support structure constructed by the above-mentioned method, including:
  • a plurality of advanced tunnels arranged at intervals along the circumference of the large-section tunnel to be constructed.
  • a plurality of backward tunnels are arranged between the plurality of preceding tunnels, and are connected with the preceding tunnels to form a supporting structure of the large-section tunnel to be constructed.
  • a large-section tunnel support structure provided by the present invention has at least the following beneficial effects:
  • the support structure of the present application is a permanent reinforced concrete support structure arranged outside the large-section tunnel. Compared with the temporary support structure in the traditional large-section tunnel, the structural strength is high, the support effect is good, there is no need to dismantle it later, and the construction is safer, which can significantly improve the construction efficiency of the large-section tunnel.
  • Fig. 1 has shown the structural representation of large-section tunnel construction method of the present invention
  • Fig. 2 has shown the sectional structure schematic diagram of the uncast concrete of the primary support structure of the large-section tunnel of the present invention
  • Figure 3 shows a large sample diagram of node A in Figure 2;
  • Fig. 4 has shown the structural schematic diagram of the leading support reinforcement and the positioning bar of the leading tunnel in Fig. 2;
  • Fig. 5 shows the schematic diagram of the effect after pouring concrete in the preceding tunnel in Fig. 4;
  • Fig. 6 has shown the structure schematic diagram after the advance support reinforcement in Fig. 3 is connected with the rear support reinforcement and the tunnel pours concrete first;
  • Fig. 7 shows the structural schematic view of the preceding tunnel in Fig. 6 after removing the concrete at its junction with the following tunnel and pouring concrete into the following tunnel;
  • Fig. 8 has shown the cross-sectional structure schematic diagram after the primary support structure of the large-section tunnel of the present invention pours concrete among Fig. 2;
  • Fig. 9 shows the cross-sectional schematic view after the secondary lining construction of the large-section tunnel of the present invention is completed
  • Fig. 10 shows a structural schematic diagram of backing plates and steel boxes at the junction of the leading tunnel and the trailing tunnel in Fig. 6;
  • Fig. 11 has shown the structural representation that backing plate is removed among Fig. 10 and construction has back row supporting reinforcement;
  • Fig. 12 has shown the structure schematic diagram after being poured with concrete in the backward tunnel in Fig. 11;
  • Fig. 13 is the three-dimensional structure schematic diagram of the backing plate and the steel box on the backing plate in Fig. 10;
  • Fig. 14 is a three-dimensional enlarged structural schematic diagram of a plurality of positioning ribs arranged on a steel box in Fig. 13;
  • Fig. 15 shows a partial three-dimensional structural schematic diagram of another embodiment of the primary support structure of the large-section tunnel of the present invention.
  • Fig. 16 is a schematic diagram of the structure of the through tunnel and the leading tunnel in Fig. 15 with reinforcing bars;
  • Fig. 17 is a structural schematic view of a section of the through tunnel and the preceding tunnel in Fig. 16 after pouring concrete.
  • the invention provides a large-section tunnel construction method, comprising the following steps:
  • Step S1 excavating a plurality of advance tunnels at intervals along the circumferential direction of the large-section tunnel to be constructed.
  • Step S2 reinforce the preceding tunnel.
  • Step S3 excavating a subsequent tunnel between multiple preceding tunnels.
  • step S4 the backward tunnel is reinforced, and the backward tunnel is connected with the preceding tunnel to form an initial support structure of the large-section tunnel to be constructed.
  • Step S5 excavating the rock mass within the support range of the initial support structure to construct a large-section tunnel.
  • the large-section tunnel construction method adopted in this application does not require additional provision of temporary supports, which reduces the workload of on-site staff and saves construction costs.
  • on-site workers do not need to additionally erect and remove temporary supports, which reduces the risk of on-site construction operations and meets the requirements for on-site safe construction operations.
  • rock mass in the embodiments includes rock or soil mass.
  • step S1 may also include:
  • Step S01 processing the opening and side slope of the large-section tunnel to be constructed.
  • Step S02 setting up the working platform.
  • the diameter of each passing tunnel 10 is generally 1.8 meters to 3 meters, and the specific diameter is designed according to the requirements of manual operation space and design thickness.
  • the shape of the backward tunnel 20 does not need to be excavated in a circular shape, because excavating the backward tunnel 20 in a circular shape will inevitably lead to the construction of the preceding tunnel.
  • the preceding tunnel 10 has a relatively large amount of reinforced concrete demolition work, which is not conducive to improving construction efficiency. It is only necessary to ensure that the rear support reinforcement bars 32 of the rear tunnel 20 can be overlapped with the advance support reinforcement bars 31 of the advanced tunnel 10 that has been constructed, but the concrete surface at the junction of the first tunnel 10 and the rear tunnel 20 must be Chisel to ensure the effective moment of inertia area of the primary support structure of the large-section tunnel.
  • the initial support structure of the large-section tunnel in this embodiment includes the initial support reinforced concrete structure, specifically including the initial support steel bar 30 and the initial support concrete, wherein the initial support steel bar 30 includes the first support Steel bars 31, positioning bars 40 and rear supporting bars 32.
  • the primary support concrete includes the concrete poured in the preceding tunnel 10 and the concrete poured in the trailing tunnel 20 .
  • step S2 the specific steps for reinforcing the leading tunnel 10 in step S2 include:
  • Step S21 setting positioning ribs on the wall of the preceding tunnel. Specifically, according to the position of the steel bars of the initial support structure of the large-section tunnel to be constructed, setting out positioning points on the wall of the preceding tunnel 10, and setting up positioning ribs 40 at the setting out points.
  • Step S22 setting the advance support reinforcement in the advance tunnel, and connecting the advance support reinforcement with the positioning reinforcement.
  • Step S23 pouring concrete into the preceding tunnel.
  • Step S4 includes:
  • step S41 the concrete at the junction of the preceding tunnel and the following tunnel is roughened, so that the positioning ribs are partially located in the following tunnel.
  • the junction of the leading tunnel 10 and the trailing tunnel 20 needs to chisel out a certain width of concrete to form a concrete chisel area 50, increasing the concrete and the trailing tunnel 10.
  • the effective connection area of the poured concrete of the tunnel 20 is not limited to be very large.
  • Step S42 setting the rear support reinforcement in the rear tunnel, and connecting the rear support reinforcement with the positioning reinforcement.
  • Step S43 pouring concrete into the backward tunnel.
  • Step S5 includes:
  • Step S51 whether the step distance meets the requirements of the working space.
  • Step S52 performing secondary lining operation.
  • the tunnel can be further strengthened through the secondary lining operation to avoid the problem of collapse after the section is hollowed out, so as to meet the construction design requirements of the tunnel and the requirements of site safety construction.
  • Step S5 includes:
  • Step S51 whether the step distance meets the requirements of the working space.
  • Step S52 whether the initial support structure can meet the force requirements.
  • Step S5 also includes step S53 of performing decoration and decoration work, and step S53 is after step S52.
  • the decoration work can make the tunnel more beautiful, so as to meet the design requirements of its appearance quality. Thus ensuring that it can be put into use normally in the later stage.
  • the tunnel 10 ahead may be constructed by using pipe jacking.
  • the on-site construction efficiency of large-section tunnel construction can be further improved, and the cost of on-site construction can be reduced, so as to meet the requirements of cost reduction and efficiency increase of on-site construction operations.
  • the preceding tunnel 10 is a circular tunnel. Of course, it can be set to other shapes such as ellipse according to the actual situation.
  • the diameter of the leading tunnel 10 is between 1.8m and 3m, and the economic benefits are more obvious when the excavation cross-sectional area of the large-section tunnel is greater than 250m 2 .
  • step S21 may include:
  • the backing plate 60 is preferably an easy-to-cut foam board or an easy-to-remove concrete formwork.
  • a release agent can be applied on the backing plate 60 .
  • Embossed lines can be provided on the end surface of the backing plate 60 in contact with the poured concrete of the preceding tunnel 10 , so that when the backing plate 60 is removed or chiseled off, the end surface at the junction of the leading tunnel 10 and the following tunnel 20 is a rough surface.
  • the positioning ribs 40 can be directly inserted into corresponding positions of the foam board.
  • the backing plate 60 is a concrete formwork
  • positioning holes can be provided on the concrete formwork in advance to facilitate the insertion of the positioning ribs 40 .
  • step S212 includes:
  • Step S41 includes:
  • this application also proposes a large-section tunnel support structure constructed using the above method, including:
  • a plurality of advanced tunnels 10 are arranged at intervals along the circumferential direction of the large-section tunnel to be constructed.
  • a plurality of backward tunnels 20 are arranged between the plurality of preceding tunnels 10 and connected with the preceding tunnels 10 to form a support structure for a large-section tunnel to be constructed.
  • the leading tunnel 10 and the trailing tunnel 20 constructed along the circumferential direction of the large-section tunnel to be constructed can adopt the warehouse jumping construction technique.
  • multiple tunnels 10 ahead and tunnels 20 behind can be constructed simultaneously.
  • the number of the leading tunnel 10 and the trailing tunnel 20 are designed to be 6 respectively, and then the large-section to be constructed can be The three preceding tunnels 10 are constructed synchronously at equal intervals in the circumferential direction of the tunnels, and then the remaining three preceding tunnels 10 are constructed synchronously.
  • the same method can be used to construct the three backward tunnels 20 at equal intervals and simultaneously, and then construct the remaining three backward tunnels 20 synchronously.
  • adopting the method of synchronous skipping construction can greatly improve the construction efficiency of large-section tunnels and shorten the construction period.
  • a large-section tunnel construction method includes the following steps:
  • Step S01 processing the opening and side slope of the large-section tunnel to be constructed.
  • Step S02 setting up the working platform.
  • Step S1 excavating a plurality of preceding tunnels 10 with circular radial sections at intervals along the circumferential direction of the large-section tunnel to be constructed.
  • Step S2 reinforce the preceding tunnel.
  • the setting out positioning point is set on the wall of the tunnel 10 in advance
  • the positioning rib 40 is set at the setting out positioning point, so that the positioning rib 40 is inserted in the leading tunnel 10 on the cave wall.
  • the advance support reinforcement bar 31 is arranged in the advance tunnel 10, and the advance support reinforcement bar 31 is bound and connected with the positioning rib 40 or fixed by welding.
  • the setting position or direction of the preliminary support reinforcement 31 is designed according to the setting position or direction of the initial support reinforcement 30 of the large-section tunnel to be constructed.
  • concrete is gradually poured into the leading tunnel 10 from inside to outside.
  • a construction section of 10-20 meters is used, and a blocking plate is installed at the end of each construction section, and concrete is poured section by section from the inside to the outside.
  • Step S3 when the concrete of the preceding tunnel has solidified to meet the design requirements, excavate the subsequent tunnel between the multiple preceding tunnels.
  • a backward tunnel 20 is arranged between every two preceding tunnels 10 .
  • the positioning ribs 40 can also play a role in positioning and guiding the excavation of the backward tunnel 20 .
  • the positioning ribs 40 can be used as The reference object avoids the deviation of the excavation direction of the backward tunnel 20, and the length of the positioning rib 40 can also be used as a reference object for the excavation diameter of the backward tunnel 20, so as to prevent the excavation diameter of the backward tunnel 20 from being too large or too small, and The connection between the advance support reinforcement bar 31 in the advance tunnel 10 and the rear support reinforcement bar 32 in the rear tunnel 20 is ensured.
  • step S4 the backward tunnel is reinforced, and the backward tunnel is connected with the preceding tunnel to form an initial support structure of the large-section tunnel to be constructed.
  • the concrete at the junction of the preceding tunnel 10 and the following tunnel 20 is roughened, and the positioning ribs 40 are partially located in the excavated but not poured following tunnel 20 .
  • the rear support reinforcement 32 is arranged in the rear tunnel 20 , and the rear support reinforcement 32 is connected with the positioning rib 40 .
  • the rear support reinforcement 32, the positioning reinforcement 40 and the advance support reinforcement 31 together constitute the primary support reinforcement 30 of the primary support structure.
  • the rear support reinforcement 32 is constructed in the same way as the advance support reinforcement 31, and can be constructed ahead of time outside the tunnel, and can also be bound on site in the tunnel.
  • both the preceding support reinforcement bar 31 and the rear support reinforcement bar 32 in this embodiment can be understood as a support reinforcement cage arranged along the length direction of the tunnel.
  • the construction method of pouring concrete in the backward tunnel 20 is the same as the concrete pouring method in the preceding tunnel 10, and both can adopt segmental pouring construction.
  • Step S5 excavating the rock mass within the support range of the initial support structure to construct a large-section tunnel.
  • the secondary lining construction is not necessary. If the primary support structure can meet the force requirements, the secondary lining construction is not required. If the primary support structure does not meet the force requirements, the secondary lining operation is carried out.
  • a construction step of the backing plate 60 is also included.
  • the backing plate 60 is preferably a foam board
  • the backing plate 60 is laid along the length direction of the tunnel 10 ahead, and a plurality of steel plates or steel boxes welded by steel plates are arranged at intervals along the length direction of the backing plate 60 70.
  • the bottom steel plate of the steel box 70 is welded with a plurality of positioning ribs 40, and the plurality of positioning ribs 40 keep a distance.
  • the top steel plate of the steel box 70 is provided with an opening 71, and the two side ends of the steel box 70 pass through.
  • One of the installation methods of the positioning rib 40 of the present embodiment is: first pass the backing plate 60 to drill holes on the wall of the tunnel 10 ahead, the depth of the hole and the distance between adjacent drilling holes are based on the length and relative distance of the positioning rib 40.
  • the spacing between adjacent positioning ribs 40 is designed.
  • the positioning rib 40 is inserted into the borehole of the wall of the preceding tunnel 10 , preferably making the bottom steel plate of the steel box 70 abut against the backing plate 60 .
  • the second installation method of the positioning rib 40 of this embodiment is: without drilling holes on the wall of the tunnel 10 ahead, the positioning rib 40 can be inserted on the backing plate 60, and the bottom steel plate of the steel box 70 can abut on the The backing plate 60 can also keep a certain distance from the backing plate 60 .
  • the concrete wraps the steel box 70, and the through side end of the steel box 70 or the opening 71 of the top steel plate facilitates the pouring of concrete into the steel box 70, so that the steel box 70 is firmly pre-buried in the tunnel 10 ahead.
  • the backing plate 60 can also be used as a template, and an embossed pattern is set on the contact surface between the backing plate 60 and the pouring concrete of the tunnel 10 ahead, and a release agent is applied.
  • the backing plate 60 can be used as a reference for the excavation of the backward tunnel 20 to ensure the excavation direction and diameter of the backward tunnel 20 .
  • the end face of the backing plate 60 facing away from the preceding tunnel 10 is completely exposed in the backward tunnel 20 .
  • the foam board can be quickly and easily removed to expose the positioning rib 40 and the concrete surface of the tunnel 10 ahead, and the concrete surface is roughened.
  • embossed textures are provided on the concrete contact surface between the backing plate 60 and the preceding tunnel 10, the chiseling process can be omitted.
  • the backing plate 60 is a formwork
  • the formwork can be directly removed. Because the mold release agent is applied, the backing plate 60 is more convenient to remove, and the backing plate 60 after removal can be reused after turnover, reducing construction costs.
  • the rear support reinforcement 32 in the tunnel 20 is constructed so that the rear support reinforcement 32 is bound or welded to the positioning reinforcement.
  • the rear support reinforcement 32 can also be directly connected to the Steel case 70 is welded and fixed.
  • the construction of the initial support structure of the large-section tunnel is completed, and the rock mass within the support range of the initial support structure can be excavated at one time to complete the construction of the large-section tunnel. construction.
  • the large-section tunnel support structure includes:
  • a plurality of advanced tunnels 10 are arranged at intervals along the circumferential direction of the large-section tunnel to be constructed.
  • a plurality of through tunnels 80 are arranged between the plurality of preceding tunnels 10, and are connected with the preceding tunnels 10 to form a supporting structure of a large-section tunnel to be constructed.
  • the through-tunnel 80 between two adjacent preceding tunnels 10 includes a plurality of through-units 81 arranged along its length direction, and the two adjacent through-units 81 of each through-tunnel 80 are spaced apart or connected.
  • FIG. 15 is a schematic diagram after the first through unit 81 of the through tunnel 80 is excavated and formed and communicated with the adjacent preceding tunnel 10 .
  • Figure 16 shows that the first through unit 81 is supported with a through support reinforcement 33, and the leading tunnel 10 adjacent to it is also supported with a corresponding length of advance support reinforcement 31, in order to facilitate the subsequent through unit 81
  • the preceding support reinforcement bar 31 supported each time is not easy to be too long, preferably the length is equal to the length of the penetration support reinforcement bar 33 supported in the first penetration unit 81 .
  • the advance support reinforcement 31 is bound or welded to the through support reinforcement 33 .
  • FIG. 17 is a schematic structural view of the first through unit 81 and the preceding tunnel 10 adjacent to the first through unit 81 after pouring concrete. After the concrete poured in the first through unit 81 reaches the design strength, the next through unit 81 can be excavated. It should be noted that the next penetrating unit 81 may be connected to the first penetrating unit 81 , or may keep a distance from the first penetrating unit 81 .
  • Through-tunnels 80 are excavated at intervals along the circumferential direction of the large-section tunnel to be constructed, and each through-tunnel 80 communicates with two adjacent preceding tunnels 10 in the circumferential direction.
  • each through-tunnel 80 is excavated in sections, for example, the length of each through-tunnel 80 is 100 meters, and it is divided into 10 through-units 81 from inside to outside, and the length of each through-unit 81 is 10 meters, of course , and other lengths are also possible.
  • the through tunnels 80 are excavated section by section from the inside to the outside, and each through tunnel 80 excavates one through unit 81 each time.
  • the advance support reinforcement 31 is constructed in the advance tunnel 10 .
  • each penetration unit 81 After the excavation of each penetration unit 81 is completed, the penetration support reinforcement 33 is supported in the penetration unit 81 , and the penetration support reinforcement 33 is bound or welded to the advance support reinforcement 31 in the adjacent preceding tunnel 10 .
  • the construction of the through support steel bars 33 in the first through unit 81 of all through tunnels 80 is completed, concrete is poured into the preceding tunnel 10, and the pouring length is the length of the first through unit 81. It should be noted that this During the section pouring construction, it is necessary to set the pouring baffle at the corresponding position.
  • the excavation of the second through-unit 81 and the corresponding construction of the through-support reinforcement bars 33 in the second through-unit 81 are carried out, and the construction is carried out step by step from the inside to the outside until all the through-units 81 construction completed.
  • the initial support structure of the large-section tunnel in this embodiment includes the initial support reinforced concrete structure, specifically including the initial support steel bar 30 and the initial support concrete, wherein the initial support steel bar 30 includes the first support Reinforcing bar 31 and through support reinforcing bar 33.
  • the primary support concrete includes the concrete poured in the preceding tunnel 10 and the concrete poured in the through tunnel 80 .
  • the initial support structure of this embodiment includes a plurality of support units arranged along the length direction of the large-section tunnel, each support unit is a ring support structure, and each support unit includes The through units 81 of reinforced concrete structure and the preceding tunnel 10 are distributed alternately.
  • the construction method of this embodiment can not only further improve the construction efficiency, but also can improve the strength of the primary support structure, especially effectively improve the binding quality of the primary support steel bars 30 .

Abstract

本发明提供了一种大断面隧道施工方法及支护结构。方法包括：步骤S1，沿拟施工大断面隧道的周向间隔开挖多个先行隧道；步骤S2，对先行隧道进行加固；步骤S3，开挖多个先行隧道之间的后行隧道；步骤S4，对后行隧道进行加固，并且使后行隧道与先行隧道连接以构成拟施工大断面隧道的初期支护结构；步骤S5，对初期支护结构的支护范围内的岩体进行开挖以施工出大断面隧道。支护结构，包括多个先行隧道，沿拟施工大断面隧道的周向间隔设置；多个后行隧道，设置在多个先行隧道之间。本申请采用的大断面隧道施工方法无需额外在大断面隧道内搭设和拆除临时支护，提高了施工效率，降低了现场工作人员的工作量、现场施工作业的风险以及施工成本。

Description

一种大断面隧道施工方法及支护结构 技术领域
本发明涉及路基的施工技术领域，特别地涉及一种大断面隧道施工方法及支护结构。
背景技术
目前，城市地下空间的开发越来越多，且断面也越来越大，相关技术中的大断面隧道施工基本为分步开挖结合分步衬砌的施工方式，或为分步开挖结合整体衬砌的施工方式，将大断面隧道分成若干小断面的隧道分步进行开挖，工艺虽然较为成熟，但其缺点十分明显。该种施工方式需要设置较多的临时支护，临时支护只起到临时稳定作用，后期需要拆除，造成巨大浪费，影响了现场施工作业的效率，也延长了施工周期。
因此，现有大断面隧道施工方式存在施工效率低，施工周期长的问题。
发明内容
针对上述现有技术中的问题，本申请提出了一种大断面隧道施工方法，解决了采用相关技术中的大断面隧道施工方式导致的现场施工效率低的问题。
本发明的大断面隧道施工方法，包括：
步骤S1，沿拟施工大断面隧道的周向间隔开挖多个先行隧道；
步骤S2，对先行隧道进行加固；
步骤S3，开挖多个先行隧道之间的后行隧道；
步骤S4，对后行隧道进行加固，并且使后行隧道与先行隧道连接以构成拟施工大断面隧道的初期支护结构；
步骤S5，对初期支护结构的支护范围内的岩体进行开挖以施工出大断面隧道。
在一个实施方式中，步骤S2包括：
步骤S21，在先行隧道的洞壁设置定位筋；
步骤S22，在先行隧道内设置先行支护钢筋，并使先行支护钢筋与定位筋连接；
步骤S23，向先行隧道内浇注混凝土。
通过本实施方式，在先行隧道内设置定位筋，以确保先行支护钢筋的安装精度，以保证初期支护结构的支护效果；在先行隧道内设置先行支护钢筋后浇注混凝土，使先行隧道形成钢筋砼结构，进一步提升初期支护结构的支护效果。
在一个实施方式中，步骤S4包括：
步骤S41，对先行隧道与后行隧道的交接处的混凝土进行凿毛处理，使定位筋局部位于后行隧道内；
步骤S42，在后行隧道内设置后行支护钢筋，并且使后行支护钢筋与定位筋连接；
步骤S43，向后行隧道内浇注混凝土。
通过本实施方式，通过对先行隧道与后行隧道的交接处的混凝土进行凿毛处理，不仅使定位筋局部位于后行隧道内，便于后行支护钢筋与定位筋的绑扎固定，而且使交接处的先行隧道形成有毛面，便于先行隧道与后行隧道的浇注混凝土紧密连接，提高初期支护结构的支护效果。
在一个实施方式中，步骤S21包括：根据拟施工大断面隧道的初期支护结构的钢筋位置，在先行隧道的洞壁设置放样定位点，并在放样定位点设置定位筋。
通过本实施方式，定位筋用于初期支护结构的安装定位，从而确保初期支护结构的钢筋能够按照预设的位置安装在先行隧道和后行隧道的洞壁内，进而确保初期支护结构对大断面隧道的有效支撑，以确保后续大断面隧道的一次性开挖作业能够成功地实施。
在一个实施方式中，步骤S5包括：
步骤S51，步距是否满足作业空间的要求；
若是，则进行防水施工；
步骤S52，进行二次衬砌作业。
通过本实施方式，通过二次衬砌作业可进一步地加固隧道，避免其由于断面挖空后塌方的问题出现，从而满足隧道的施工设计要求以及现场安全施工的要求。
在一个实施方式中，步骤S5包括：
步骤S51，步距是否满足作业空间的要求；
若是，则进行防水施工；
步骤S52，初期支护结构是否能够满足受力要求；
若是，则不进行二次衬砌作业；
若否，则进行二次衬砌作业。
通过本实施方式，在满足隧道施工设计的前提下，可减少施工作业的程序，从而提高了现场施工作业的效率，同时节约了施工成本。
在一个实施方式中，步骤S5还包括进行装饰装修作业的步骤S53，步骤S53在步骤S52之后。
通过本实施方式，装饰装修作业能够使隧道更加的美观，从而满足其外观质量设计要求。进而确保其后期能够正常地投入使用。
在一个实施方式中，
步骤S21包括：
S211，对先行隧道拟与后行隧道交接处铺设垫板；
S212，在垫板上插设定位筋；
步骤S41包括：
S411，凿除垫板，使定位筋局部位于后行隧道内；
S412，对先行隧道与后行隧道的交接处的混凝土进行凿毛处理。
通过本实施方式，通过提前在先行隧道拟与后行隧道交接处铺设垫板，后期施工后行隧道时，无需凿除交接处的先行隧道的混凝土结构，只需凿除交接处的垫板即可，大大提高了施工效率，降低了工作强度。另外，铺设垫板时，还可在其表面涂刷脱模剂，后行隧道开挖完成后，可直接整体拆除垫板，进一步提高了施工效率，且拆除的垫板可周转再次使用，也降低了施工成本。垫板与先行隧道的接触端面可设置压花纹路，使垫板被拆除后凿除后，先行隧道在交接处的混凝土表面形成毛面，无需对其再进行凿毛施工。
在一个实施方式中，步骤S212包括：
S212a，在定位筋的一端设置钢板；
S212b，将定位筋的另一端插入垫板内。
通过本实施方式，在定位筋的一端设置钢板，先行隧道浇注混凝土后，钢板被预埋在先行隧道内，而后行隧道浇注混凝土后，定位筋部分被预埋在后行隧道内，提高了初期支护结构的结构强度。另外，钢板也可限制定位筋的位移量，避免定位筋在垫板上位移或倾斜，保证定位筋的安装精度。另外，先行支护钢筋可直接与钢板焊接实现其与定位筋的间接连接，提高了焊接施工效率。
上述技术特征可以各种适合的方式组合或由等效的技术特征来替代，只要能够达到本发明的目的。
本发明提供的一种大断面隧道施工方法，与现有技术相比，至少具备有以下有益效果：
通过沿拟施工的大断面隧道周向间隔开挖并加固先行隧道，并且在相邻的两个先行隧道之间开挖并加固后行隧道，使后行隧道与先行隧道连接构成拟施工大断面隧道的初期支护结构后，再对初期支护结构的支护范围内的岩体进行开挖以施工出大断面隧道。相比于传统的隧道支护结构而言，本申请中采用的大断面隧道施工方法无需额外在大断面隧道内搭设和拆除临时支护，提高了施工效率，降低了现场工作人员的工作量、现场施工作业的风险以及施工成本。另外，相比于现有的大断面隧道的先开挖后支护的方式而言，本申请采用先支护后开挖的方式，施工更安全。
本发明还提出一种利用上述方法施工出的大断面隧道支护结构，包括：
多个先行隧道，沿拟施工大断面隧道的周向间隔设置；以及
多个后行隧道，设置在多个先行隧道之间，且与先行隧道连接以构成拟施工大断面隧道的支护结构。
本发明提供的一种大断面隧道支护结构，与现有技术相比，至少具备有以下有益效果： 本申请的支护结构是设置在大断面隧道外的永久钢筋砼支护结构，相比于传统的大断面隧道内的临时支护结构而言，结构强度高，支护效果好，后期无需拆除，施工也更安全，可明显提高大断面隧道的施工效率高。
附图说明
在下文中将基于实施例并参考附图来对本发明进行更详细的描述。其中：
图1显示了本发明的大断面隧道施工方法结构示意图；
图2显示了本发明大断面隧道的初期支护结构未浇注混凝土的断面结构示意图；
图3显示了图2中的节点A的大样图；
图4显示了图2中的先行隧道的先行支护钢筋及定位筋的结构示意图；
图5显示了图4中的先行隧道浇注混凝土后的效果示意图；
图6显示了图3中的先行支护钢筋与后行支护钢筋连接且先行隧道浇注混凝土后的结构示意图；
图7显示了图6中的先行隧道凿除其与后行隧道交接处的混凝土并且后行隧道浇注混凝土后的结构示意图；
图8显示了图2中本发明的大断面隧道的初期支护结构浇注混凝土后的断面结构示意图；
图9显示了本发明的大断面隧道二次衬砌施工完成后的断面示意图；
图10显示了图6中先行隧道与后行隧道交接处还设置有垫板和钢箱的结构示意图；
图11显示了图10中垫板拆除并施工有后行支护钢筋的结构示意图；
图12显示了图11中后行隧道内浇注有混凝土后的结构示意图；
图13为图10中垫板及垫板上的钢箱的立体结构示意图；
图14为图13中一个钢箱上设置多个定位筋的立体放大结构示意图；
图15显示了本发明大断面隧道的初期支护结构的另一种实施方式的局部立体结构示意图；
图16为图15中的贯通隧道和先行隧道内支设有钢筋的结构示意图；
图17为图16中一段贯通隧道和先行隧道浇注有混凝土后的结构示意图。
在附图中，相同的部件使用相同的附图标记。附图并未按照实际的比例。
附图标记：
10、先行隧道；20、后行隧道；30、初期支护钢筋；31、先行支护钢筋；32、后行支护钢筋；33、贯通支护钢筋；40、定位筋；50、混凝土凿除区；60、垫板；70、钢箱；71、开口；80、贯通隧道；81、贯通单元。
具体实施方式
下面将结合附图1至附图17对本发明作进一步说明。
本发明提供了一种大断面隧道施工方法，包括以下步骤：
步骤S1，沿拟施工大断面隧道的周向间隔开挖多个先行隧道。
步骤S2，对先行隧道进行加固。
步骤S3，开挖多个先行隧道之间的后行隧道。
步骤S4，对后行隧道进行加固，并且使后行隧道与先行隧道连接以构成拟施工大断面隧道的初期支护结构。
步骤S5，对初期支护结构的支护范围内的岩体进行开挖以施工出大断面隧道。
根据上述步骤，通过沿拟施工的大断面隧道周向间隔开挖并加固先行隧道10，并且在相邻的两个先行隧道10之间开挖并加固后行隧道20，使后行隧道20与先行隧道10连接构成拟施工大断面隧道的初期支护结构后，再对初期支护结构的支护范围内的岩体进行开挖以施工出大断面隧道。这样避免了相关技术中采用大断面分成若干小断面进行挖掘的方式所导致的临时支护较多，后期拆除麻烦的问题。从而提高了大断面隧道施工的效率。
本申请中采用的大断面隧道施工方法无需额外设置临时支护，这样降低了现场工作人员的工作量，节约施工成本。同时，现场工作人员无需额外的搭设和拆除临时支架，降低了现场施工作业的风险，满足现场安全施工作业的要求。
需要说明的是，实施例中的岩体包括岩石或土体。
需要说明的是，在实施步骤S1前，还可以包括：
步骤S01，对拟施工的大断面隧道的洞口及边坡进行处理。
步骤S02，搭设作业台架。其中，搭设作业台架时，要做好防护，使每一个单独作业的圆形的先行隧道10有独立的作业环境，减少作业面之间的干扰。在实施步骤S1时，每个贯通的先行隧道10的洞径一般为1.8米至3米，具体的洞径结合人工操作空间及设计厚度的要求进行设计。
需要说明的是，在开挖成型的先行隧之间的后行隧道20时，后行隧道20的形状不必再按圆形开挖，因为按圆形开挖后行隧道20，必然导致先行施工的先行隧道10有较大量的钢筋砼破除工作，不利于提高施工效率。只需保证后行隧道20的后行支护钢筋32可与已施工的先行隧道10的先行支护钢筋31进行搭接即可，但要将先行隧道10与后行隧道20交接处的砼表面凿毛，以保证大断面隧道的初期支护结构的有效惯性矩面积。
需要说明的是，本实施例中的大断面隧道的初期支护结构包括初期支护钢筋砼结构，具体包括初期支护钢筋30和初期支护混凝土，其中，初期支护钢筋30包括先行支护钢筋31、定位筋40以及后行支护钢筋32。初期支护混凝土包括先行隧道10内浇注的混凝土以及后行隧道20内浇注的混凝土。
具体的，步骤S2中对先行隧道10进行加固的具体步骤包括：
步骤S21，在先行隧道的洞壁设置定位筋。具体为，根据拟施工大断面隧道的初期支护结构的钢筋位置，在先行隧道10的洞壁设置放样定位点，并在放样定位点设置定位筋40。
步骤S22，在先行隧道内设置先行支护钢筋，并使先行支护钢筋与定位筋连接。
步骤S23，向先行隧道内浇注混凝土。
步骤S4包括：
步骤S41，对先行隧道与后行隧道的交接处的混凝土进行凿毛处理，使定位筋局部位于后行隧道内。为了提高先行隧道10与后行隧道20的连接效果，先行隧道10与后行隧道20交接处需要凿除一定的宽度的混凝土，形成混凝土凿除区50，增大先行隧道10的混凝土与后行隧道20浇注的混凝土的有效连接面积。
步骤S42，在后行隧道内设置后行支护钢筋，并且使后行支护钢筋与定位筋连接。
步骤S43，向后行隧道内浇注混凝土。
步骤S5包括：
步骤S51，步距是否满足作业空间的要求。
若是，则进行防水施工。
步骤S52，进行二次衬砌作业。
根据上述步骤，通过二次衬砌作业可进一步地加固隧道，避免其由于断面挖空后塌方的问题出现，从而满足隧道的施工设计要求以及现场安全施工的要求。
需要说明的是，当大断面隧道的初期支护结构满足受力要求时，可不进行衬砌作业。在此基础上，可对施工方法步骤进行调整，具体如下：步骤S5包括：
步骤S51，步距是否满足作业空间的要求。
若是，则进行防水施工。
步骤S52，初期支护结构是否能够满足受力要求。
若是，则不进行二次衬砌作业。
若否，则进行二次衬砌作业。
步骤S5还包括进行装饰装修作业的步骤S53，步骤S53在步骤S52之后。
根据上述步骤，装饰装修作业能够使隧道更加的美观，从而满足其外观质量设计要求。进而确保其后期能够正常地投入使用。
具体地，在一个实施例中，当满足顶管施工条件时，可采用顶管对先行隧道10进行施工。这样可进一步地提高大断面隧道施工的现场施工效率，降低现场施工的成本，从而满足现场施工作业降本增效的要求。
具体地，在一个实施例中，先行隧道10为圆形隧道。当然可根据实际情况，将其设置成椭圆等其他形状。
具体地，在一个实施例中，先行隧道10的洞径在1.8m至3m之间，大断面隧道的开挖断面面积大于250m 2时经济效益较为明显。
在一个实施例中，步骤S21可包括：
S211，对先行隧道拟与后行隧道交接处铺设垫板。其中，垫板60优选为易凿除的泡沫板或易拆除的混凝土模板。当垫板60为混凝土模板时，为了脱模方便，可在垫板60上涂刷脱模剂。垫板60与先行隧道10的浇注混凝土接触的端面可以设置压花纹路，从而当垫板60被拆除或凿除后，先行隧道10与后行隧道20交接处的端面为毛面。
S212，在垫板上插设定位筋。当垫板60为泡沫板时，定位筋40可直接插在泡沫板的相应位置。当垫板60为混凝土模板时，可提前在混凝土模板上设置定位孔，以便于定位筋40插入。
在一个实施例中，步骤S212包括：
S212a，在定位筋的一端设置钢板。
S212b，将定位筋的另一端插入垫板内。
步骤S41包括：
S411，凿除垫板，使定位筋局部位于后行隧道内。
S412，对先行隧道与后行隧道的交接处的混凝土进行凿毛处理。
基于本发明的方法，本申请还提出一种利用上述方法施工出的大断面隧道支护结构，包括：
多个先行隧道10，沿拟施工大断面隧道的周向间隔设置；以及
多个后行隧道20，设置在多个先行隧道10之间，且与先行隧道10连接以构成拟施工大断面隧道的支护结构。
需要说明的是，本实施例的沿拟施工大断面隧道的周向施工的先行隧道10和后行隧道20可以采用跳仓法施工工艺。其中，先行隧道10和后行隧道20均可同步施工多个。比如，根据拟施工大断面隧道的径向断面的周长以及先行隧道10和后行隧道20的洞径设计先行隧道10和后行隧道20的数量分别为6个，则可沿拟施工大断面隧道的周向等间距均匀的同步施工3个先行隧道10，再同步施工剩余的3个先行隧道10。同理，可采用同样的方法，等间距均匀的同步施工3个后行隧道20，再同步施工剩余的3个后行隧道20。相比于依次顺序施工6个先行隧道10和6个后行隧道20而言，采用上述同步跳仓施工的方式可大大提高大断面隧道的施工效率，缩短施工工期。
下面阐述本申请的三个完整的实施例：
实施例一
如图1至图9所示，一种大断面隧道施工方法，包括以下步骤：
步骤S01，对拟施工的大断面隧道的洞口及边坡进行处理。
步骤S02，搭设作业台架。
步骤S1，沿拟施工大断面隧道的周向间隔开挖多个径向断面为圆形的先行隧道10。
步骤S2，对先行隧道进行加固。具体的：根据拟施工大断面隧道的初期支护结构的钢筋位置，在先行隧道10的洞壁设置放样定位点，并在放样定位点设置定位筋40，使定位筋40插设在先行隧道10的洞壁上。在先行隧道10内设置先行支护钢筋31，并使先行支护钢筋31与定位筋40绑扎连接或焊接固定。先行支护钢筋31的设置位置或方向根据拟施工的大断面隧道的初期支护钢筋30的设置位置或方向进行设计。
先行支护钢筋31与定位筋40连接后，向先行隧道10内由里向外逐步浇注混凝土。具体的，以10-20米为一个施工段，每个施工段的末端设置封堵板，由里向外逐段浇注混凝土。
需要说明的是，在大断面隧道施工前，已经完成了其开挖尺寸以及其初期支护结构的设计，即在大断面隧道施工前，先行隧道10的开挖位置、开挖洞径、开挖间隔、先行支护钢筋31的位置和方向、定位筋40的位置和数量均已经完成设计。
步骤S3，当先行隧道的混凝土凝固达到设计要求后，开挖多个先行隧道之间的后行隧道。每两个先行隧道10之间设置一个后行隧道20。后行隧道20开挖过程中，定位筋40还可起到定位引导后行隧道20开挖的作用。由于多个定位筋40是沿先行隧道10的长度方向分布，且沿先行隧道10长度方向的相邻定位筋40的间距可能是一定的，因此开挖后行隧道20时，定位筋40可作为参照物，避免后行隧道20开挖方向偏移，定位筋40的长度也可作为后行隧道20开挖洞径的参照物，避免后行隧道20开挖洞径过大或过小，以及保证先行隧道10内先行支护钢筋31和后行隧道20内后行支护钢筋32的连接。
步骤S4，对后行隧道进行加固，并且使后行隧道与先行隧道连接以构成拟施工大断面隧道的初期支护结构。
具体的：对先行隧道10与后行隧道20的交接处的混凝土进行凿毛处理，并且使定位筋40局部位于已开挖未浇注的后行隧道20内。
在后行隧道20内设置后行支护钢筋32，并且使后行支护钢筋32与定位筋40连接。后行支护钢筋32、定位筋40及先行支护钢筋31共同构成初期支护结构的初期支护钢筋30。后行支护钢筋32与先行支护钢筋31施工方式一样，可在隧道外提前施工完成，也可在隧道内现场绑扎施工。实际上，本实施例的先行支护钢筋31和后行支护钢筋32均可理解为沿隧道长度方向设置的支护钢筋笼。
后行支护钢筋32施工完成后，向后行隧道20内浇注混凝土。后行隧道20内浇注混凝土的施工方式与先行隧道10内混凝土浇注方式相同，可均采用分段浇注施工。
步骤S5，对初期支护结构的支护范围内的岩体进行开挖以施工出大断面隧道。
大断面隧道成型后，判断其步距是否满足作业空间的要求。
若是，则进行防水施工。然后再进行二次衬砌作业。最后进行装饰装修作业。
当然，二次衬砌施工是非必须的，若初期支护结构可以满足受力要求，则可不进行二次衬砌施工，若若初期支护结构不满足受力要求，则进行二次衬砌作业。
实施例二
如图10至图14所示的一种大断面隧道施工方法，本实施例的施工方法与实施例一大致相同，区别在于：
还包括垫板60的施工步骤。
具体的，在先行隧道10的洞壁上施工定位筋40前，先在先行隧道10拟与所述后行隧道20交接处铺设垫板60。再将定位筋40穿过垫板60。作为本实施例的优选方案，垫板60优选为泡沫板，垫板60沿先行隧道10的长度方向铺设，沿垫板60的长度方向间隔设置有多个钢板或由钢板焊接而成的钢箱70。钢箱70的底端钢板上焊接有多个定位筋40，多个定位筋40保持间距，钢箱70的顶端钢板上设置有开口71，钢箱70的两个侧端贯通。
本实施例的定位筋40的安装方式之一是：先穿过垫板60在先行隧道10的洞壁上钻孔，钻孔的孔深和相邻钻孔间距根据定位筋40的长度和相邻定位筋40的间距而设计。将定位筋40穿过垫板60后插入先行隧道10的洞壁的钻孔内，优选的使钢箱70的底端钢板抵接在垫板60上。
本实施例的定位筋40的安装方式之二是：无需在先行隧道10的洞壁上钻孔，将定位筋40插在垫板60上即可，钢箱70的底端钢板可抵接在垫板60上，也可与垫板60保持一定的间距。
先行隧道10浇注混凝土时，混凝土包裹钢箱70，钢箱70的贯通的侧端或其顶端钢板的开口71便于浇注混凝土进入钢箱70内，使钢箱70牢固的预埋在先行隧道10的浇注混凝土内。垫板60还可作为模板使用，在垫板60与先行隧道10浇注混凝土接触面设置压花纹路并涂刷脱模剂。
相应的，在开挖后行隧道20的过程中，垫板60可作为后行隧道20开挖的参照物，以保证后行隧道20的开挖方向和洞径。当后行隧道20开挖完成后，垫板60背对先行隧道10的端面完全暴露在后行隧道20内。
若垫板60为泡沫板，可快速轻松的凿除泡沫板，以露出定位筋40和先行隧道10的混凝土面，并对该混凝土面进行凿毛处理。当然，若垫板60与先行隧道10的混凝土接触面设置有压花纹路，可省去凿毛处理工艺。
若垫板60为模板，可直接拆除模板，由于涂刷有脱模剂，垫板60拆除较方便，拆除后的垫板60可周转后再次使用，降低施工成本。
垫板60凿除或拆除后，施工后行隧道20内的后行支护钢筋32，使后行支护钢筋32与定位钢筋绑扎或焊接固定，当然，后行支护钢筋32也可直接与钢箱70焊接固定。
后行支护钢筋32施工完成后，向后行隧道20内浇注混凝土，混凝土填满后行隧道20且包裹后行支护钢筋32、定位筋40和钢箱70的局部。
待后行隧道20内浇注混凝土达到设计要求后，大断面隧道的初期支护结构施工完成，可对该初期支护结构的支护范围内的岩体进行一次性开挖，完成大断面隧道的施工。
实施例三
如图15至图17所示，大断面隧道支护结构，包括：
多个先行隧道10，沿拟施工大断面隧道的周向间隔设置；以及
多个贯通隧道80，设置在多个先行隧道10之间，且与先行隧道10连接以构成拟施工大断面隧道的支护结构。其中，相邻两个先行隧道10之间的贯通隧道80包括沿其长度方向排列的多个贯通单元81，每个贯通隧道80的相邻两个贯通单元81保持间距或相连接。
如图15所示，相邻两个先行隧道10之间的拟施工的贯通隧道80被分为多个沿其长度方向排列的贯通单元81。其中，图15所示为该贯通隧道80的第一个贯通单元81被开挖成型并与相邻的先行隧道10连通后的示意图。
图16所示为该第一个贯通单元81内支设有贯通支护钢筋33，并且与其相邻的先行隧道10内也支设有相应长度的先行支护钢筋31，为了便于后续贯通单元81的开挖，每次支设的先行支护钢筋31不易过长，优选为长度等于该第一个贯通单元81内支设的贯通支护钢筋33的长度。先行支护钢筋31与贯通支护钢筋33绑扎或焊接固定。
图17所示为第一个贯通单元81及与该第一个贯通单元81相邻的先行隧道10内浇注有混凝土后的结构示意图。待该第一个贯通单元81浇注的混凝土达到设计强度后，可进行下一个贯通单元81的开挖。需要说明的是，下一个贯通单元81可以是与该第一个贯通单元81相连接，也可以是与该第一个贯通单元81保持间距。
本实施例的大断面隧道的施工方法，与实施例一大致相同，区别在于：
沿拟施工大断面隧道的周向间隔开挖多个先行隧道10。
沿拟施工大断面隧道的周向间隔开挖贯通隧道80，每个贯通隧道80连通该周向上的相邻的两个先行隧道10。其中，每个贯通隧道80分段开挖，比如，每个贯通隧道80的长度为100米，将其由内向外分为10个贯通单元81，每个贯通单元81的长度为10米，当然，也可以是其他长度。由内向外逐段开挖贯通隧道80，每个贯通隧道80每次开挖一个贯通单元81。
根据每个贯通单元81的长度，在先行隧道10内施工先行支护钢筋31。
每个贯通单元81开挖完成后，在该贯通单元81内支设贯通支护钢筋33，并将贯通支护钢筋33与相邻的先行隧道10内的先行支护钢筋31绑扎或焊接固定。待所有贯通隧道80的 第一个贯通单元81内的贯通支护钢筋33施工完成后，向先行隧道10内浇注混凝土，浇注长度为第一个贯通单元81的长度，需要说明的是，这种分段浇注施工时需要在相应的位置设置浇筑挡板。待混凝土达到凝固设计要求后，进行第二个贯通单元81的开挖以及相应的第二个贯通单元81内的贯通支护钢筋33的施工，依次由内向外逐段施工，直至所有的贯通单元81施工完成。
需要说明的是，本实施例中的大断面隧道的初期支护结构包括初期支护钢筋砼结构，具体包括初期支护钢筋30和初期支护混凝土，其中，初期支护钢筋30包括先行支护钢筋31以及贯通支护钢筋33。初期支护混凝土包括先行隧道10内浇注的混凝土以及贯通隧道80内浇注的混凝土。
可以理解的是，本实施例的初期支护结构包括沿大断面隧道的长度方向排列的多个支护单元，每个支护单元为环形支护结构，每个支护单元包括沿其周向交替分布的钢筋砼结构的贯通单元81和先行隧道10。
相比于实施例一而言，本实施例的施工方法不仅可以进一步提高施工效率，而且可以提高初期支护结构的强度，尤其是有效提升初期支护钢筋30的绑扎质量。
在本发明的描述中，需要理解的是，术语“上”、“下”、“底”、“顶”、“前”、“后”、“内”、“外”、“左”、“右”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。
虽然在本文中参照了特定的实施方式来描述本发明，但是应该理解的是，这些实施例仅仅是本发明的原理和应用的示例。因此应该理解的是，可以对示例性的实施例进行许多修改，并且可以设计出其他的布置，只要不偏离所附权利要求所限定的本发明的精神和范围。应该理解的是，可以通过不同于原始权利要求所描述的方式来结合不同的从属权利要求和本文中所述的特征。还可以理解的是，结合单独实施例所描述的特征可以使用在其他所述实施例中。

Claims (10)

  1. 一种大断面隧道施工方法，其特征在于，包括：
    步骤S1，沿拟施工大断面隧道的周向间隔开挖多个先行隧道；
    步骤S2，对所述先行隧道进行加固；
    步骤S3，开挖多个所述先行隧道之间的后行隧道；
    步骤S4，对所述后行隧道进行加固，并且使所述后行隧道与所述先行隧道连接以构成所述拟施工大断面隧道的初期支护结构；
    步骤S5，对所述初期支护结构的支护范围内的岩体进行开挖以施工出所述大断面隧道。
  2. 根据权利要求1所述的大断面隧道施工方法，其特征在于，所述步骤S2包括：
    步骤S21，在所述先行隧道的洞壁设置定位筋；
    步骤S22，在所述先行隧道内设置先行支护钢筋，并使所述先行支护钢筋与所述定位筋连接；
    步骤S23，向所述先行隧道内浇注混凝土。
  3. 根据权利要求2所述的大断面隧道施工方法，其特征在于，所述步骤S4包括：
    步骤S41，对所述先行隧道与所述后行隧道的交接处的混凝土进行凿毛处理，使所述定位筋局部位于所述后行隧道内；
    步骤S42，在所述后行隧道内设置后行支护钢筋，并且使所述后行支护钢筋与所述定位筋连接；
    步骤S43，向所述后行隧道内浇注混凝土。
  4. 根据权利要求2所述的大断面隧道施工方法，其特征在于，所述步骤S21包括：根据所述拟施工大断面隧道的初期支护结构的钢筋位置，在所述先行隧道的洞壁设置放样定位点，并在所述放样定位点设置所述定位筋。
  5. 根据权利要求1所述的大断面隧道施工方法，其特征在于，所述步骤S5包括：
    步骤S51，步距是否满足作业空间的要求；
    若是，则进行防水施工；
    步骤S52，进行二次衬砌作业。
  6. 根据权利要求1所述的大断面隧道施工方法，其特征在于，所述步骤S5包括：
    步骤S51，步距是否满足作业空间的要求；
    若是，则进行防水施工；
    步骤S52，所述初期支护结构是否能够满足受力要求；
    若是，则不进行二次衬砌作业；
    若否，则进行二次衬砌作业。
  7. 根据权利要求5或6所述的大断面隧道施工方法，其特征在于，所述步骤S5还包括进行装饰装修作业的步骤S53，所述步骤S53在所述步骤S52之后。
  8. 根据权利要求3所述的大断面隧道施工方法，其特征在于，
    所述步骤S21包括：
    S211，对所述先行隧道拟与所述后行隧道交接处铺设垫板；
    S212，在所述垫板上插设所述定位筋；
    所述步骤S41包括：
    S411，凿除所述垫板，使所述定位筋局部位于所述后行隧道内；
    S412，对所述先行隧道与所述后行隧道的交接处的混凝土进行凿毛处理。
  9. 根据权利要求8所述的大断面隧道施工方法，其特征在于，所述步骤S212包括：
    S212a，在所述定位筋的一端设置钢板；
    S212b，将所述定位筋的另一端插入所述垫板内。
  10. 一种利用如权利要求1至9中任一项所述方法施工出的大断面隧道支护结构，其特征在于，包括：
    多个先行隧道，沿拟施工大断面隧道的周向间隔设置；以及
    多个后行隧道，设置在所述多个先行隧道之间，且与所述先行隧道连接以构成所述拟施工大断面隧道的支护结构。
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