Method for manufacturing special pipe sections for mechanical connection of access channels

Abstract

The application discloses a preparation method of a special pipe piece of a mechanical method connecting channel, and comprises the following steps: 1) four reinforced concrete pipe pieces are respectively prefabricated; 2) fiber fillers and whiskers are mixed into concrete raw materials to obtain concrete mixture, and the fiber concrete pipe piece is prefabricated by using the concrete mixture to perform pouring forming; 3) two fiber concrete pipe pieces are spliced, and then the two fiber concrete pipe pieces are spliced with four reinforced concrete pipe pieces to form a pipe ring, a corrugated pipe and a first corrugated pipe embedded in the pipe ring form a connected annular hole, a prestressed tendon is penetrated through the annular hole, and after the prestressed tendon is tensioned and anchored by using an anchoring tooth block, the special pipe piece of the mechanical method connecting channel is prepared. The overall rigidity, compressive strength, bending strength, stability, durability, bearing capacity and deformation resistance of the fiber concrete pipe piece are improved, and the technical problem that internal force and deformation are generated at a cutting position of the special pipe piece during cutting construction is effectively solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of tunnel engineering construction. BACKGROUND

[0002] In the continuous development of mechanized engineering, the use of shield method or pipe jacking method and other full-mechanical process to excavate the connecting passage instead of mine method excavation is the development trend of tunnel engineering. The mechanical method connecting passage construction refers to the method of cutting the main tunnel segment by pipe jacking method or shield method, then excavating and assembling the segment, and cutting the segment at the other end of the tunnel to complete the receiving.

[0003] The mechanical method connecting passage construction method is to pre-leave a special three-ring through-seam special segment at the portal position of the main tunnel connecting passage construction as a cuttable portal. In the cutting process, the cutting method of "half-cut on both sides + full-cut in the middle" is adopted. The three-ring segment has a ring width of 1.5m, and the thickness is the same as that of the ordinary segment, which is 350mm. The three-ring assembly method is through-seam assembly, and the other segments of the main tunnel adopt staggered joint assembly method. The purpose of using special ring is to maintain the stability of the main tunnel structure during cutting, and also effectively resist the additional stress generated by the portal during cutting. The mechanical method connecting passage construction method becomes the first choice of non-frozen construction method to meet the safety, convenience, economy and efficiency.

[0004] At present, the construction methods of the connecting passage mainly include open cut method, mine method, freezing and underground excavation method, pipe jacking method, etc. For the open cut method, the ground is directly excavated at the surface and supported by a support structure to the designed elevation, and then the soil is backfilled. This method is suitable for construction sites with good site conditions and good soil quality, but it is not suitable for crowded cities with dense surrounding buildings. The mine method uses the traditional underground excavation mode to grout the connecting passage construction site for reinforcement. When the connecting passage is excavated by the mine method, the soil within a certain range of the connecting passage position needs to be grouted and reinforced. The reinforcement depth and range are generally large, and the construction period is long. The arch top needs to be reinforced to a large extent, and then the excavation is carried out from the reserved hole position of the special pipe piece in the main tunnel. Then, the soil or rock within the range of the connecting passage is excavated according to the mine method. The advantages of this method are lower cost, smaller ground occupation, shorter time occupation, and shorter construction period. However, the construction risk is high, and strict construction is required. If water and sand inrush occurs in the tunnel, it will have a great impact on the formed tunnel, and in severe cases, it will also cause ground collapse. The working environment is poor, the construction range is small, and the health of the workers is affected. The pipe jacking method is a mechanized construction technology, which also needs to reinforce the stratum at the connecting passage, and then the pipe jacking method is used for construction. During the construction process, although the safety is high, due to the imperfect equipment, the water and soil pressure on the outside of the tunnel during the cutting of the main tunnel pipe piece may cause water inrush in the tunnel. In addition, the rear thrust of the pipe jacking machine will exert additional force on the lining structure of the main tunnel, affecting the safety of the tunnel. In the freezing and underground excavation method, the soil within a certain range around the connecting passage is perforated, and then low-temperature salt water is injected. After the soil reaches a certain bearing capacity, the underground excavation method is used for construction. Although this method has mature technology, improper handling of low-temperature salt water or equipment failure during construction may cause serious safety accidents.

[0005] In order to overcome the many shortcomings of non-mechanical construction methods, mechanical construction technology has been explored and practiced in recent years. According to the type of machinery used, it is generally divided into two categories, namely pipe jacking method and shield method. In general, the pipe jacking method is more commonly used because it requires less construction space and can meet the requirements of narrow space in the main tunnel. The construction efficiency is good. However, existing pipe jacking construction cases are concentrated in good strata, and the soil at the hole needs to be reinforced to have a certain self-stability, which facilitates the removal of the prefabricated pipe piece at the connecting passage hole, and then the pipe jacking is carried out. The construction and reinforcement cost is high, and it has a certain impact on the construction period.

[0006] In summary, compared with the non-mechanical construction method, the mechanical construction method can shorten the construction period to a certain extent, does not need to carry out large-area reinforcement, can reduce the reinforcement cost, and eliminates the structural damage and environmental influence caused by the freezing reinforcement and freezing-thawing.

[0007] In the mechanical construction method, when the pipe segment is directly cut by the pipe jacking machine or the shield machine, the pipe segment structure not only bears the water and soil load pressure, but also generates internal force and deformation to a certain extent at the special pipe segment cutting position, and the existing pipe segment structure has the defects of low rigidity and insufficient anti-deformation capacity. SUMMARY

[0008] The present application aims to provide a preparation method of a mechanical method connecting channel special pipe segment.

[0009] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0010] A preparation method of a mechanical method connecting channel special pipe segment, the special pipe segment comprising four steel reinforced concrete pipe segments connected in a head-to-tail manner, and fiber concrete pipe segments provided with prestressed tendons and connected to both sides of the four steel reinforced concrete pipe segments, the preparation method of the special pipe segment comprising the following steps:

[0011] 1) four steel reinforced concrete pipe segments are respectively prefabricated, anchoring tooth blocks for anchoring the prestressed tendons are made on the steel reinforced concrete pipe segments adjacent to the fiber concrete pipe segments, and a first bellows pipe is pre-buried;

[0012] 2) a fiber filler and a whisker are added to a concrete raw material to obtain a concrete mixture, a steel support provided with a pipe hole and a bellows pipe penetrating through the pipe hole are first placed in a pipe segment mold, and the fiber concrete pipe segments are prefabricated by pouring and forming the concrete mixture;

[0013] 3) two fiber concrete pipe segments of step 2) are assembled, and then assembled with four steel reinforced concrete pipe segments to form a pipe ring, the bellows pipe and the first bellows pipe pre-buried in the pipe ring form a ring-shaped hole, the prestressed tendons penetrate through the ring-shaped hole, and the mechanical method connecting channel special pipe segment is obtained after the prestressed tendons are tensioned and anchored by the anchoring tooth blocks.

[0014] In step 2), the fiber filler is one or more of polypropylene fiber, steel fiber, polyvinyl alcohol fiber and aramid fiber, and the fiber filler is added at 0.1-1% of the mass of the concrete raw material; the whisker is ettringite whisker or calcium sulfate whisker, and the whisker is added at 0.5-2% of the mass of the concrete raw material; in step 3), the prestressed tendons are made of steel strands.

[0015] In step 2), the fiber filler is composed of polypropylene fiber and polyvinyl alcohol fiber in a mass ratio of (1-3):(2-4).

[0016] In step 2), the fiber filler is composed of polypropylene fibers and aramid fibers in a mass ratio of (2-4):(0.5-1).

[0017] In step 2), the polypropylene fibers have a length of 10-16 mm and are composed of three kinds of polypropylene fibers with diameters of 0.04-0.08 mm, 0.1-0.2 mm and 0.4-0.8 mm in a mass ratio of (1-2):(2-4):(1-3).

[0018] In step 2), the polyvinyl alcohol fibers have a length of 5-10 mm.

[0019] In step 2), the aramid fibers have a length of 5-10 mm.

[0020] The corrugated pipe is embedded on the outer side of the fiber concrete segment in the thickness direction. The eccentricity can be appropriately adjusted according to design requirements, and the distance between the corrugated pipe and the outer edge of the segment should not be less than the thickness of the segment protective layer.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The present application adds whiskers and fiber fillers, so that the components of the concrete can jointly act together, and have the characteristics of multiple crack opening, strain hardening under tensile, bending and shear load, thus having the advantages of high toughness and anti-deformation ability, etc. The pre-embedded prestressed reinforcement also improves the overall stiffness, compressive strength, bending strength, stability, durability, bearing capacity, anti-deformation ability and other properties of the fiber concrete segment, effectively solving the technical problem of internal force and deformation at the cutting part of the special segment during cutting construction. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The figure is a structural diagram of the special segment of the present application.

[0024] Among them, 1, 2, 3, 4-steel reinforced concrete segment, 5-anchoring tooth block, 6-steel support, 7, 8-fiber concrete segment, 9-corrugated pipe. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with specific embodiments and drawings.

[0026] A mechanical method connecting channel special segment, such as Figure 1As shown, it is a ring-shaped pipe piece, including reinforced concrete pipe piece 1, reinforced concrete pipe piece 2, reinforced concrete pipe piece 3, reinforced concrete pipe piece 4 connected end to end, fiber concrete pipe piece 8 and fiber concrete pipe piece 7 with embedded prestressed tendon connected with reinforced concrete pipe piece 1 and reinforced concrete pipe piece 4 respectively, the reserved port and the anchoring tooth block 5 are arranged on the reinforced concrete pipe piece 1 and the reinforced concrete pipe piece 4, the prestressed tendon is arranged in the corrugated pipe 9, and the prestressed tendon is tensioned and anchored through the anchoring tooth block 5, and the fiber concrete pipe piece is formed by pouring the concrete raw material mixed with a certain proportion of whisker and artificial synthetic fiber.

[0027] Example 1

[0028] The concrete raw material mainly consists of the following components: cement 705 parts, fly ash 135 parts, quartz sand 545 parts, coal gangue coarse aggregate 75 parts (coal gangue is crushed to a particle size of 10-20 mm), water 195 parts, and polycarboxylic acid water reducer 4 parts. The standards of each raw material meet the standards of the concrete pipe piece raw material.

[0029] The preparation method of the special pipe piece of the mechanical method connecting channel comprises the following steps:

[0030] 1) four reinforced concrete pipe pieces are respectively prefabricated (the above-mentioned concrete raw material composition is adopted, and the prefabrication is carried out by using the existing conventional technology), the reserved port and the anchoring tooth block for anchoring the prestressed tendon are made on the reinforced concrete pipe pieces adjacent to the fiber concrete pipe pieces, and the first corrugated pipe is embedded;

[0031] 2) the coal gangue coarse aggregate, the quartz sand, the cement, the fly ash, the ettringite whisker are premixed, the polycarboxylic acid water reducer is dissolved in water, then the fiber filler (the fiber filler is composed of polypropylene fiber and polyvinyl alcohol fiber at a mass ratio of 3:2) is added, mixed, a fiber filler dispersion liquid is obtained, the fiber filler dispersion liquid is slowly added to the above-mentioned premixed raw material, a concrete mixture is obtained, the steel support 6 with a reserved pipe hole and the corrugated pipe passing through the pipe hole are placed in the pipe piece mold, the concrete mixture is used for pouring, forming, troweling, steam curing, demolding and secondary water curing, and the fiber concrete pipe piece is obtained; the fiber filler is mixed at 0.9% of the mass of the concrete raw material, and the whisker is mixed at 1% of the mass of the concrete raw material;

[0032] 3) the two fiber concrete pipe pieces in step 2) are spliced, and then spliced with the four reinforced concrete pipe pieces to form a pipe ring, the corrugated pipe and the first corrugated pipe embedded in the pipe ring form a continuous ring-shaped hole, the prestressed tendon (steel strand) is penetrated through the ring-shaped hole, and the prestressed tendon is tensioned and anchored by using the anchoring tooth block, and the special pipe piece of the mechanical method connecting channel is prepared.

[0033] In step 2), the length of the polypropylene fiber is 13 mm, which is composed of three kinds of polypropylene fibers with diameters of 0.06 mm, 0.2 mm and 0.6 mm in a mass ratio of 1:2:3; the length of the polyvinyl alcohol fiber is 5 mm. The length of the ettringite whisker is 0.03 mm, and the diameter is 1 µm.

[0034] It is detected that, compared with the concrete segment with no whisker and fiber filler and pre-embedded prestressed reinforcement, the overall rigidity, compressive strength, flexural strength, stability, bearing capacity and anti-deformation capacity of the fiber concrete segment of the embodiment 1 of the present application are greatly improved, and the comprehensive performance is obviously improved.

[0035] Embodiment 2

[0036] The concrete raw materials mainly consist of the following components: cement 700 parts, fly ash 125 parts, quartz sand 505 parts, coal gangue coarse aggregate 90 parts (coal gangue is crushed to a particle size of 10-20 mm), water 180 parts, and polycarboxylic acid water reducer 5 parts. The standards of the raw materials meet the raw material standards of the concrete segment.

[0037] A preparation method of a mechanical method connecting channel special segment, comprising the following steps:

[0038] 1) four reinforced concrete segments are respectively pre-prepared, the anchoring tooth block for anchoring the prestressed reinforcement is prepared on the reinforced concrete segment adjacent to the fiber concrete segment, and a first bellows is pre-embedded;

[0039] 2) the fiber filler (the fiber filler is composed of polypropylene fiber and aramid fiber in a mass ratio of 4:1) and the whisker (calcium sulfate whisker) are mixed into the concrete raw materials according to the method of embodiment 1 to obtain a concrete mixture, the steel support with a reserved pipe hole and the bellows penetrating through the pipe hole are first placed in the segment mold, the concrete mixture is used for casting forming, troweling, steam curing, demolding and secondary water curing to obtain a fiber concrete segment; the fiber filler is mixed in an amount of 0.3% of the mass of the concrete raw materials, and the whisker is mixed in an amount of 0.5% of the mass of the concrete raw materials;

[0040] 3) the two fiber concrete segments of step 2) are spliced, and then spliced with the four reinforced concrete segments to form a pipe ring, the bellows and the first bellows pre-embedded in the pipe ring form a communicating annular channel, the prestressed reinforcement (steel strand) penetrates through the annular channel, and after the prestressed reinforcement is tensioned and anchored by the anchoring tooth block, a mechanical method connecting channel special segment is prepared.

[0041] In step 2), the length of the polypropylene fiber is 10 mm, which is composed of three kinds of polypropylene fibers with diameters of 0.04 mm, 0.1 mm and 0.8 mm in a mass ratio of 2:3:2, and the length of the aramid fiber is 5 mm. The length of the calcium sulfate whisker is 0.1 mm, and the diameter is 3 µm.

[0042] The overall rigidity, compressive strength, flexural strength, stability, bearing capacity and deformation resistance of the fiber concrete segment of Example 2 are greatly improved, and the comprehensive performance is obviously improved, compared with the concrete segment without the whisker and fiber filler and with the pre-embedded prestressed reinforcement.

[0043] Example 3

[0044] The difference between this example and Example 1 is that the cellulose filler added is polypropylene fiber and aramid fiber, and the mass ratio of the two is 3:1, the fiber filler is mixed at 0.6% of the mass of the concrete raw materials, and the calcium aluminate whisker is mixed at 1.5% of the mass of the concrete raw materials.

[0045] The overall rigidity, compressive strength, flexural strength, stability, bearing capacity and deformation resistance of the fiber concrete segment of Example 3 are greatly improved, and the comprehensive performance is obviously improved, compared with the concrete segment without the whisker and fiber filler and with the pre-embedded prestressed reinforcement.

[0046] Example 4

[0047] The difference between this example and Example 2 is that the cellulose filler added is polypropylene fiber and polyvinyl alcohol fiber, and the mass ratio of the two is 1:3, the fiber filler is mixed at 0.2% of the mass of the concrete raw materials, and the calcium sulfate whisker is mixed at 0.5% of the mass of the concrete raw materials.

[0048] The overall rigidity, compressive strength, flexural strength, stability, bearing capacity and deformation resistance of the fiber concrete segment of Example 4 are greatly improved, and the comprehensive performance is obviously improved, compared with the concrete segment without the whisker and fiber filler and with the pre-embedded prestressed reinforcement.

[0049] Example 5

[0050] The difference between this example and Example 2 is that the cellulose filler added is aramid fiber and polyvinyl alcohol fiber, and the mass ratio of the two is 2:1, the fiber filler is mixed at 0.5% of the mass of the concrete raw materials, and the calcium sulfate whisker is mixed at 0.9% of the mass of the concrete raw materials.

[0051] The overall rigidity, compressive strength, flexural strength, stability, bearing capacity and deformation resistance of the fiber concrete segment of Example 5 are greatly improved, and the comprehensive performance is obviously improved, compared with the concrete segment without the whisker and fiber filler and with the pre-embedded prestressed reinforcement.

[0052] Example 6

[0053] The embodiment is different from the embodiment 1 in that the cellulose filler added is steel fiber and polyvinyl alcohol fiber, the mass ratio of the two is 3:1, the fiber filler is mixed in 0.8% of the mass of the concrete raw materials, and the calcium sulfate whisker is mixed in 1.2% of the mass of the concrete raw materials.

[0054] It is detected that compared with the concrete pipe segment without the whisker and the fiber filler and the concrete pipe segment with the embedded prestressed reinforcement, the overall rigidity, the compressive strength, the bending strength, the stability, the bearing capacity and the anti-deformation capacity of the fiber concrete pipe segment of the embodiment 6 are greatly improved, and the comprehensive performance is obviously improved.

Claims

1. A method for producing a special pipe section for a mechanical tieback channel, characterized in that The special pipe piece comprises four reinforced concrete pipe pieces connected head to tail, fiber concrete pipe pieces provided with prestressed tendons and connected to two sides of the four reinforced concrete pipe pieces respectively, and a preparation method of the special pipe piece, comprising the following steps: 1) four reinforced concrete pipe pieces are respectively prefabricated, anchor teeth blocks for anchoring prestressed tendons are made on the reinforced concrete pipe pieces adjacent to the fiber concrete pipe pieces, and a first bellows pipe is pre-buried; 2) a fiber filler and a whisker are mixed in concrete raw materials to obtain a concrete mixture, a steel support provided with a pipe hole and a bellows pipe penetrating through the pipe hole are first placed in a pipe piece mold, and the fiber concrete pipe piece is prefabricated by pouring and forming with the concrete mixture; 3) two fiber concrete pipe pieces in step 2) are spliced, and then spliced with four reinforced concrete pipe pieces to form a pipe ring, the bellows pipe and the first bellows pipe pre-buried in the pipe ring form a communicating annular channel, the prestressed tendon penetrates through the annular channel, and the mechanical method connection channel special pipe piece is prepared after the prestressed tendon is tensioned and anchored by the anchor teeth blocks; In step 2), the fiber filler is one or more than two of polypropylene fiber, steel fiber, polyvinyl alcohol fiber and aramid fiber, and the fiber filler is mixed in an amount of 0.1-1% of the mass of the concrete raw materials; the whisker is ettringite whisker or calcium sulfate whisker, and the whisker is mixed in an amount of 0.5-2% of the mass of the concrete raw materials; in step 3), the prestressed tendon is made of steel strand.

2. The method of claim 1, wherein the method further comprises the step of: In step 2), the fiber filler is composed of polypropylene fiber and polyvinyl alcohol fiber in a mass ratio of (1-3):(2-4). ​ 3. The method of claim 1, wherein the method further comprises the step of: In step 2), the fiber filler is composed of polypropylene fiber and aramid fiber in a mass ratio of (2-4):(0.5-1). ​ 4. The method of claim 1, 2 or 3, wherein the method further comprises the step of: In step 2), the length of the polypropylene fiber is 10-16 mm, which is composed of three kinds of polypropylene fibers with diameters of 0.04-0.08 mm, 0.1-0.2 mm and 0.4-0.8 mm in a mass ratio of (1-2):(2-4):(1-3). ​ 5. The method of claim 1 or 2, wherein the special pipe section is a mechanical-joint contact tunnel pipe section. In step 2), the length of the polyvinyl alcohol fiber is 5-10 mm.

6. The method of claim 1 or 3, wherein the special pipe section is a mechanical-joint contact tunnel pipe section. In step 2), the length of the aramid fiber is 5-10 mm.

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