Construction structure for treating collapse of top arches of small and medium-sized section tunnels

Abstract

The utility model provides a small and medium-sized section tunnel top arch collapse treatment construction structure which comprises a tunnel, a slag filling area, a sand bag throwing and filling area, a concrete supporting mold and a concrete pouring area. The slag filling area is arranged on the lower half portion of the tunnel top arch collapse area and used as a bottom support. The sand bag throwing and filling area is arranged at the upper half part of the tunnel top arch collapse area, is positioned above the slag filling area, is used as an upper support and is matched with the slag filling area to fill the tunnel section; the concrete supporting mold is arranged with the contour faces of the sand bag throwing and filling area and the slag filling area as supporting faces and serves as a supporting mold for top arch concrete pouring. The concrete pouring area is located above the concrete supporting mold and used for forming a concrete tunnel top arch. According to the structure, original slag materials and abrasive belts serve as supporting assemblies, concrete pouring is completed in cooperation with a concrete supporting mold, the construction period is shortened, and the construction safety risk is reduced.

Description

Technical Field

[0001] This utility model relates to the field of tunnel collapse treatment, specifically, to a construction structure for treating the collapse of the roof arch of a medium-sized tunnel. Background Technology

[0002] The existing method for dealing with tunnel arch collapse is to remove the rock debris from the collapse site to the initial excavation line, promptly carry out initial shotcrete support to seal the support surface, then carry out re-excavation according to the boundary line of the re-excavation line and complete the initial support of the upper half and the arch support of the arch, and then pour concrete for the arch of the collapsed section to form a protective support structure.

[0003] Existing technologies are time-consuming and unsafe. When the upper cavity near the collapse section continues to experience rockfalls and collapses, the surrounding rock is in an extremely unstable state, which can easily cause on-site workers to refuse to work due to concerns about their personal safety.

[0004] To address the safety issues of on-site workers and the problem of excessively long construction periods, it is necessary to improve the existing methods for handling the collapse of the roof arch of small and medium-sized tunnels. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a construction structure for handling the collapse of the roof arch of small and medium-sized tunnels, which offers high safety and a shorter construction period.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is: a construction structure for treating the collapse of the arch of a medium-sized tunnel, including a tunnel, a slag filling area, a sandbag throwing area, a concrete support formwork, and a concrete pouring area.

[0007] The slag filling area is located in the lower half of the tunnel arch collapse area and serves as a bottom support.

[0008] The sandbag filling area is located in the upper part of the tunnel arch collapse area, above the slag filling area, and is used as an upper support to help the slag filling area fill the tunnel cross section.

[0009] The concrete support mold is set with the outline of the sandbag filling area and the slag filling area as the support surface, and serves as the support mold for the pouring of the top arch concrete.

[0010] The concrete pouring area is located above the concrete support mold and is used to form the roof arch of the concrete tunnel.

[0011] Preferably, a retaining wall is installed on the collapsed side of the tunnel near the slag filling area.

[0012] Preferably, the height of the slag retaining wall is lower than the overall height of the slag filling area.

[0013] Preferably, the filling material in the slag filling area is the slag material formed on-site by the collapse.

[0014] Preferably, the overall height of the sandbag filling area is at least one-third of the tunnel height.

[0015] Preferably, the concrete support formwork includes a support mesh formed by connecting several steel bars and steel pipes. The steel pipes are laid along the tunnel axis, with the inner end of the steel pipes reaching the tunnel face. The steel bars are laid on top of the steel pipes and fixed to the steel pipes. The steel bars are bent to a shape consistent with the arc surface of the tunnel arch.

[0016] Preferably, the steel pipe is a φ42-45mm steel pipe, and the spacing between the pipes is at least 30cm.

[0017] Preferably, the reinforcing bar is a φ22-25mm reinforcing bar.

[0018] Preferably, a grouting pipe is pre-embedded in the concrete pouring area, with the lower end of the grouting pipe extending to the concrete support mold and the upper end extending to the upper surface of the concrete pouring area.

[0019] Preferably, the concrete pouring area extends at least to the upper edge of the retaining wall on the side adjacent to the retaining wall.

[0020] This utility model has substantial features and progress compared to the prior art. Specifically, in the case of a collapsed tunnel, this utility model abandons the traditional scaffolding construction method and uses slag and sandbags as the supporting structure for the top arch. Then, formwork is erected at the top and concrete is poured to complete the repair and reinforcement of the top arch. The slag comes from the slag formed by the collapse, which eliminates the process of transporting the slag away from the site. This shortens the construction period and avoids the risk of secondary collapse during the transportation of the slag. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of the construction structure for treating the collapse of the tunnel arch in small and medium-sized sections according to this utility model.

[0022] In the diagram: 1. Tunnel; 2. Slag filling area; 3. Sandbag throwing area; 4. Concrete support formwork; 5. Concrete pouring area; 6. Slag retaining wall; 41. Steel pipe; 42. Reinforcing steel. Detailed Implementation

[0023] The technical solution of this utility model will be further described in detail below through specific embodiments.

[0024] like Figure 1 As shown, a construction structure for treating the collapse of the arch of a medium-sized tunnel includes a tunnel 1, a slag filling area 2, a sandbag throwing area 3, a concrete support formwork 4, and a concrete pouring area 5.

[0025] The slag filling area 2 is located in the lower half of the collapsed area of ​​the tunnel 1 arch and is used as a bottom support. The slag filling area 2 is filled with slag material, which comes from the soil and rocks formed by the collapse. In the specific operation, dump trucks equipped with backhoes can be used to advance the construction from outside the tunnel to inside the tunnel. Loaders and backhoes are used on-site at the tunnel face to backfill the slag. The slag is filled below the arch shoulder using the above-mentioned mechanical method.

[0026] The sandbag filling area 3 is located in the upper part of the tunnel arch collapse area, above the slag filling area 2, and is used as an upper support. It works in conjunction with the slag filling area 2 to fill the tunnel 1 cross section. Due to the required density of the upper support, the slag filling method may have structural deficiencies and operational inconveniences. Therefore, the upper part is filled with sandbags to supplement the upper surface and provide a support foundation for the construction of the concrete support formwork 4.

[0027] The concrete support mold 4 is set with the outline of the sandbag filling area 3 and the slag filling area 2 as the support surface, and serves as the support mold for the pouring of the top arch concrete. Specifically, in this embodiment, cantilevered steel pipes 41 with a diameter of φ42-45mm are set along the tunnel axis with a row spacing of at least 30cm, and the inner end of the steel pipe 41 reaches the tunnel face directly.

[0028] Reinforcing bar 42 is used as reinforcement for poured concrete. Its specifications are φ22-25mm. Unevenly thrown reinforcing bars are adjusted using bamboo poles or reinforcing bar hooks. Specifically, during implementation, one end of the reinforcing bar is bent into a hook shape and hung on a steel pipe. It is pushed manually with a pole, and the reinforcing bar forms an arc using its own weight. The reinforcing bar is bent to a shape consistent with the arc surface of the tunnel arch.

[0029] Workers who are throwing sandbags and laying steel bars must be positioned on stable steel arches that have been installed at the small pile number to ensure work safety.

[0030] The concrete pouring area is located above the concrete support formwork and is used to form the concrete tunnel arch. Specifically, in this embodiment, pumped self-compacting concrete is used. Intermittent pouring is employed during the initial pouring phase to utilize the initial setting of the concrete to seal any gaps in the slag. The concrete pump pipe is erected on the upper platform of the completed arch. Concrete is transported using concrete mixer trucks. The minimum thickness of the poured concrete is not less than 1.5m, and the concrete pouring area extends at least to the upper edge of the retaining wall on the side adjacent to it.

[0031] In other embodiments, to facilitate grouting operations, a grouting pipe 7 is pre-embedded in the concrete pouring area. The lower end of the grouting pipe 7 extends to the concrete support mold 4, and the upper end extends to the upper surface of the concrete pouring area 5.

[0032] In other embodiments, to ensure the safety of the working environment, before the work in the slag filling area 2 is carried out, a retaining wall 6 is set up on the collapsed side of the tunnel 1 near the slag filling area. Specifically, the retaining wall 6 is erected on the outer edge of the slag accumulation area using scaffolding and walkways. To meet the stability requirements of the slag material, long steel pipes are buried as internal tie rods, and short steel pipes are fixed at the buried end of the long steel pipes to achieve a pull-out effect. The tie rods are set up in layers according to the progress of slag filling. Diagonal bracing is set up on the outside of the retaining wall using scaffolding. In addition, to ensure the stability of the retaining wall, the contact parts between the scaffolding and the tunnel sidewall are connected to the existing steel arch frame by spot welding.

[0033] Specifically, in this embodiment, the height of the retaining wall is lower than the overall height of the slag filling area, the slag filling material in the slag filling area is the on-site slag material formed by the collapse, and the overall height of the sandbag filling area is at least one-third of the tunnel height.

[0034] After the above operations are completed and the self-compacting concrete reaches the required strength, the retaining wall and slag will be removed in layers and transported to the slag yard outside the tunnel.

[0035] In addition, due to the over-excavation of the right-side wall caused by the collapse, the cavity of the right-side wall was filled with slag during the backfilling process. This inevitably caused the slag material under the already poured concrete on the right side to fall during the demolition of the slag pile, failing to meet the load-bearing requirements of the concrete arch. Therefore, it was necessary to replace the slag material on the right side. The replacement was carried out by using composite beams welded from 18# I-beams for support and backfilling with concrete. After the poured concrete reached a certain strength, the slag material on the left side was removed first. The slag material on the right side was removed using a segmented excavation, segmented jointing, and segmented backfilling method. After excavating 0.8–1.2m at a time on the right side, composite beams welded from 18# I-beams were installed at the foot of the poured concrete arch. The upper part supported the concrete, and the lower part made close contact with the bottom slab. Steel wedges were added to the top surface of the composite beams near the concrete to ensure close contact. Then, formwork was erected, workers manually placed the beams, and concrete was poured until the replacement was completed.

[0036] This scheme was tested during the construction of the Lianghekou Tunnel. The maximum burial depth of the tunnel is 320m. When the tunnel advance reached 524m, the top arch collapsed. Drawing on the experience of the soil-filling method for arch construction, the "slag-filling method" was used to treat the collapse and a reinforced concrete arch beam was successfully poured. Through monitoring and measurement, all displacements were within the design allowable range, meeting the requirements for the stability of the surrounding rock and safe tunneling, and achieving the expected results.

[0037] Finally, it should be noted that: the preferred embodiments of this patent have been described in detail above, but this patent is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this patent.

Claims

1. A construction structure for treating a tunnel crown collapse of a small and medium cross section, characterized by: The tunnel, the slag filling area, the sandbag filling area, the concrete support mold and the concrete pouring area are included. The slag filling area is arranged at the lower half of the tunnel vault collapse area and is used as the bottom support. The sandbag filling area is arranged at the upper half of the tunnel vault collapse area and is located above the slag filling area and is used as the upper support to fill the tunnel section together with the slag filling area. The concrete support mold is arranged with the profile surface of the sandbag filling area and the slag filling area as the support surface and is used as the support mold for the concrete pouring of the tunnel vault. The concrete pouring area is located above the concrete support mold and is used to form the concrete tunnel vault.

2. The construction structure for treating the collapse of the crown of a small-to-medium cross-section tunnel according to claim 1, characterized in that: The collapse side of the tunnel is arranged with a slag retaining wall near the slag filling area.

3. The construction structure for treating the collapse of the crown of a small-to-medium cross-section tunnel according to claim 2, characterized in that: The height of the slag retaining wall is lower than the overall height of the slag filling area.

4. The construction structure for treating the collapse of the crown of a small-to-medium cross-section tunnel according to claim 1, characterized in that: The slag filling material of the slag filling area is the on-site slag material formed by the collapse.

5. The construction structure for treating the collapse of the crown of a small-to-medium cross-section tunnel according to claim 1, characterized in that: The overall height of the sandbag filling area is at least one third of the height of the tunnel.

6. The small and medium cross-section tunnel crown collapse treatment construction structure according to claim 1, characterized in that: The concrete support mold includes a support net formed by a plurality of steel bars and steel pipes, the steel pipes are laid along the tunnel axis, the inner end of the steel pipes reaches the tunnel face, the steel bars are laid above the steel pipes and are fixed with the steel pipes, and the steel bars are bent to the shape consistent with the circular surface of the tunnel vault.

7. The construction structure for treating the collapse of the crown of a small-to-medium cross-section tunnel according to claim 6, characterized in that: The steel pipes are φ42-45mm steel pipes, and the row distance is at least 30cm.

8. The construction structure for treating the collapse of the crown of a small-to-medium cross-section tunnel according to claim 6, characterized in that: The steel bars are φ22-25mm steel bars.

9. The small and medium cross-section tunnel crown collapse treatment construction structure according to claim 1, characterized in that: The concrete pouring area is pre-buried with a grouting pipe, the lower end of the grouting pipe extends to the concrete support mold, and the upper end of the grouting pipe extends to the upper end surface of the concrete pouring area.

10. The small and medium cross-section tunnel crown collapse treatment construction structure according to claim 1, characterized in that: The concrete pouring area extends at least to the upper edge of the retaining wall on the side near the retaining wall.

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