Construction method of building end wall of separate repair tunnel

Abstract

The present invention discloses a construction method for building a tunnel end wall, aiming to solve the problems of difficult joint handling, difficult section template support and poor stability in the construction of the end wall of two single-line tunnels in a large-section double-track tunnel, difficult to ensure the contour surface of the reserved opening, complicated procedures, and difficult technology. The present invention uses two lining trolleys to cooperate with + scaffolding to build the end wall of two single-line tunnels in a large-section double-track tunnel, which reduces the construction process, improves the construction progress, and avoids safety risks; two-line lining trolleys are used to support the tunnel opening of the separate repair tunnel, and the lining of the opening in each tunnel is cast with the end wall as a whole, reducing the joints at the opening, and the integrity and waterproof effect of the concrete are good; two lining trolleys are used as the support template at the repair opening, and the reserved opening has a good molding effect; using a combined support system of two lining trolleys + scaffolding, the overall support system is simple to implement, and the support system has good strength, rigidity, and stability.

Description

Technical Field

[0001] The invention relates to the technical field of tunnels, and in particular to a construction method for building an end wall of a divided tunnel. Background Art

[0002] Based on the requirements of relevant planning, design and engineering construction, some tunnel projects need to divide two single-track tunnels through a double-track tunnel at some node locations, and the exposed part of the lining connection between the two single-track tunnels with different spans needs to be equipped with a head wall; the existing construction method is to support the two single-track tunnels at the designed position and then manually chisel away the end wall. Since the cross-sectional height at the division point is as high as more than 20m, the amount of scaffolding and chiseling work is large and the construction safety risk is high; and the construction sequence is often to carry out the end wall concrete construction after the lining of the two single-track tunnels is completed. There are many problems such as difficult to handle joints, difficulty in supporting large-section formwork and poor stability, difficulty in ensuring the contour surface of reserved openings, complicated construction procedures, and difficult construction technology.

[0003] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0004] The purpose of the present invention is to provide a method for building a tunnel end wall to solve the problems in the prior art of building a large-section double-track tunnel into two single-track tunnel end walls, such as difficult joint treatment, difficulty in supporting large-section formwork and poor stability, difficulty in ensuring the contour surface of reserved openings, complicated construction procedures, and difficult construction technology.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A construction method for building a tunnel end wall is designed, comprising the following steps:

[0007] (1) The cross section of the double-track tunnel extends forward from the boundary mileage to the design thickness of the end wall. At the same time, the cross section of the double-track tunnel is enlarged to allow the single-track lining trolley to travel within the inner contour of the double-track tunnel cross section lining;

[0008] (2) Before the end wall is constructed, the cross-section lining of the double-track tunnel is constructed to the front section of the end wall. The two single-track tunnels are then reserved for a certain length of end lining and subsequent overall construction of the end wall.

[0009] (3) The two single-track tunnel lining trolleys move to the end wall position and are positioned and locked firmly according to the measurement;

[0010] (4) After tying the required steel bars for the end wall according to the design, the end formwork and the end wall formwork are installed based on the two single-track tunnel lining trolleys. The end wall formwork is fixed by internal and external bracing;

[0011] (5) After fixing is completed, pour the lining and end wall;

[0012] (6) After the concrete reaches the required strength, the formwork is removed and the surface is polished and maintained in time after removal of the formwork.

[0013] In step (4), in order to ensure that the lining end surface is flat, each template is sealed with bamboo plywood inside and wooden board outside.

[0014] In step (4), the template is fixed by welding an I-beam on a trolley to fix the wooden board, and seamless steel pipes are used to reinforce the waterproof board frame as diagonal braces.

[0015] In the step (4), a casting hole and an exhaust hole are pre-buried at the arch top position of the end wall.

[0016] In the step (5), two delivery pumps are used for pouring at the same time, and the pouring windows and the pouring holes of the vault of two single-track tunnel lining trolleys are poured symmetrically in layers and compartments from bottom to top.

[0017] In step (5), when the concrete is poured to the height of the top of the trolley, the pumping pipe is moved to the reserved pumping pipe of the end wall template, and poured upward in sequence according to the layered symmetry principle. When it is 2m away from the highest point, the delivery pipe is connected to the reserved pouring pipe of the arch; the pouring of the arch is considered to be completed when concrete flows out of the exhaust pipe.

[0018] Compared with the prior art, the main beneficial technical effects of the present invention are:

[0019] (1) The original construction method of manually chiseling away the end wall after supporting the two single-track tunnels at the designed position was changed to supporting the end wall thickness through multiple excavations of the double-track section. This eliminated the work of supporting the two-track tunnels and the pneumatic pick chiseling work for the subsequent scaffolding erection, reduced the construction procedures, improved the construction progress, and avoided the safety risks of erecting tall scaffolding.

[0020] (2) Two-line lining trolleys are used to support the tunnel openings of the separate repair tunnels. The lining of the tunnel openings in each tunnel is cast in an integrated manner with the end wall, which reduces the joints at the tunnel openings and improves the integrity and waterproofing effect of the concrete.

[0021] (3) Using two lining trolleys and supporting formwork at the repair opening, the reserved opening has a good forming effect.

[0022] (4) The combined support system of two lining trolleys and scaffolding is used. The overall support system is simple to construct and has good strength, rigidity and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic construction plane diagram of the end wall position originally designed in the embodiment of the present invention.

[0024] Figure 2 It is a schematic diagram of the optimized end wall construction section in an embodiment of the present invention.

[0025] Figure 3 This is a construction plan diagram of the end wall originally designed in an embodiment of the present invention.

[0026] Figure 4 This is a diagram of the optimized end wall construction plan in an embodiment of the present invention.

[0027] Figure 5 This is a diagram showing the effect of the end wall formwork after installation and reinforcement in an embodiment of the present invention.

[0028] Figure 6 The following are on-site photos of the pouring process of the end wall in the embodiment of the present invention.

[0029] Figure 7 This is a site photo of the end wall after it is built in the embodiment of the present invention.

[0030] In the above figure, 1 is the tunnel of Line II, 2 is the tunnel of Line I, 3 is the clean rock column at the bifurcation, 4 and 5 are the head walls, 6 is the clean rock column at the bifurcation, 7 and 8 are the head walls, 9 is the top surface of the inner rail, 10 is the separately cast end wall, and 11 is the integrally cast end wall. DETAILED DESCRIPTION

[0031] The specific implementation modes of the present invention are described below in conjunction with the accompanying drawings and examples. However, the following examples are only used to illustrate the present invention in detail and do not limit the scope of the present invention in any way.

[0032] Example: Construction of the end wall of a tunnel

[0033] 1. Project Overview

[0034] The exit portal section of Gaoligong Mountain Tunnel is set as a double-track station section and tunnel. It is built into two single-track tunnels, Line Ⅰ and Line Ⅱ, from D1K226+295. A retaining wall is set at the exposed part of the lining connection of different spans between the two single-track tunnels. The thickness of the retaining wall is 0.8m. After the excavation and support of Line Ⅰ and Line Ⅱ, the thickness of the end wall is removed by manual jackhammer, and then the same level of masonry as the lining is used for integral pouring.

[0035] 2. Construction method

[0036] (1) Excavation at the end wall

[0037] As the section height at the repair site reaches 20m, the scaffolding and excavation work is large and the safety risk is high. During construction, the double-line section is extended from the dividing mileage forward to the end wall thickness (0.8m), and the excavation of the Line I and Line II tunnels within the end wall thickness range and the excavation of the end wall excavation are converted into double-line section excavation.

[0038] (2) Lining construction at the end wall

[0039] The original design was to carry out the end wall concrete construction after the lining of Line I and Line II was completed (see Figure 1 , Figure 3 ), the main problems of this plan include difficult joint treatment, difficulty in supporting large-section formwork, poor stability and quality, difficulty in ensuring the contour surface of reserved openings, complicated construction procedures and great construction difficulty.

[0040] After in-depth research on the existing construction problems, the original design was optimized to two lining trolleys + scaffolding to solve the construction problem of the end wall of two single-track tunnels in a large-section double-track tunnel (see Figure 2 , Figure 4 ).

[0041] The construction method is as follows:

[0042] Step 1: The double-track section extends forward from the boundary mileage by the thickness of the end wall (0.8m). Since the original design of the inner contour section of the lining of Lines I and II invades the double-track section, if the lining trolleys of Lines I and II are used as supporting templates, the double-track section needs to be enlarged to allow the single-track lining trolley to move into the inner contour surface of the double-track section lining.

[0043] Step 2: Before constructing the end wall, first construct the double-line section lining to the front section of the end wall, and then construct the lining of the reserved repair section of line I, the 1.0m lining of the reserved end of the repair section of line II, and the end wall as a whole.

[0044] Step 3: The lining trolleys of Line I and Line II move to D1K226+295 (end wall position) and are positioned according to the measurement and the screws are locked securely.

[0045] Step 4: After tying the steel bars according to the design, install the end formwork and end wall formwork based on the lining trolleys of line I and line II. The end wall formwork is fixed by internal and external bracing. To ensure the flatness of the lining end surface, bamboo plywood is used inside and wooden boards are used outside to block the wooden boards. The wooden boards are fixed by welding I-beams on the trolleys, and seamless steel pipes are used to reinforce the waterproof board pedestals. Due to the large cross-section, the pouring holes and exhaust holes are pre-buried at the end wall arch position. See the fixing effect and pre-buried pipes. Figure 5 .

[0046] Step 5: After the reinforcement is completed, the lining and end wall are poured. Two delivery pumps are used for pouring at the same time. The pouring windows of the lining trolleys of Line I and Line II and the pouring holes of the arch are poured symmetrically from bottom to top in layers and compartments. When the concrete is poured to the height of the top of the trolley, the pumping pipe can be moved to the reserved pumping pipe of the end wall template, and poured upward in sequence according to the principle of layered symmetry. When it is 2m away from the highest point, the delivery pipe is connected to the reserved pouring pipe of the arch. The pouring is considered completed when concrete flows out of the exhaust pipe during the arch pouring. For the pouring process, see. Figure 6 .

[0047] Step 6: After the concrete reaches 75% strength, remove the formwork and polish and maintain the surface in time. Figure 7 .

[0048] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. However, those skilled in the art will appreciate that, without departing from the concept of the present invention, the specific parameters in the above embodiments may be changed, or related components, structures and materials may be replaced by equivalents, thereby forming multiple specific embodiments, which are all within the common variation range of the present invention and will not be described in detail one by one here.

Claims

1. A construction method for building a tunnel end wall, characterized in that: The steps include: (1) The design thickness of the double-track tunnel section extending from the boundary mileage forward to the end wall is 0.8m. When using two single-track tunnel lining trolleys as supporting templates, the double-track tunnel section is enlarged at the same time to allow the single-track lining trolley to travel within the inner contour surface of the double-track tunnel section lining; (2) Before the construction of the end wall, the lining of the double-track tunnel section is constructed to the front section of the end wall. The two single-track tunnels are then reserved for the repair section lining, with 1.0m of end lining and subsequent end wall overall construction reserved, so as to achieve the integrated casting of the end lining and end wall of the two single-track tunnels; (3) The two single-track tunnel lining trolleys move to the end wall position and are positioned and locked firmly according to the measurement; (4) After tying the required steel bars for the end wall according to the design, the end formwork and the end wall formwork are installed based on the two single-line tunnel lining trolleys. The end wall formwork is fixed by internal and external bracing. The formwork is fixed by welding the I-beam on the trolley to fix the wooden board, and seamless steel pipes are used to reinforce the waterproof board pedestal; (5) After fixing is completed, pour the lining and end wall; (6) After the poured concrete reaches the specified strength, the formwork shall be removed and the surface shall be polished and maintained in time.

2. The construction method for building the end wall of a separate repair tunnel according to claim 1, characterized in that: In step (4), in order to make the lining end surface flat, each template is sealed with bamboo plywood inside and wooden board outside.

3. The construction method for building the end wall of a separate repair tunnel according to claims 1 and 2 is characterized in that: In the step (4), a casting hole and an exhaust hole are pre-buried at the arch top position of the end wall.

4. The construction method for building the end wall of a separate tunnel according to claim 1, characterized in that: In the step (5), two delivery pumps are used for pouring at the same time, and the pouring windows and the pouring holes of the vault of two single-track tunnel lining trolleys are poured symmetrically in layers and compartments from bottom to top.

5. The construction method for building the end wall of a separate tunnel according to claim 4, characterized in that: In step (5), when the concrete is poured to the height of the top of the trolley, the pumping pipe is moved to the reserved pumping pipe of the end wall template, and poured upward in sequence according to the layered symmetry principle. When the distance from the highest point is 2 to 3 meters, the delivery pipe is connected to the reserved pouring pipe of the arch; the pouring of the arch is completed when concrete flows out of the exhaust pipe.

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