Construction method of prestressed shield tunnel contact channel structure

Abstract

The invention discloses a construction method of a prestressed shield tunnel connection channel structure, which comprises the following steps: S1, prefabricating prestressed anchoring duct piece blocks and prestressed common duct piece blocks, splicing into a continuous multi-ring prestressed pipe ring, forming a prestressed shield tunnel structure, arranging a plurality of prestressed ducts positioned in the section in the prestressed pipe ring, and forming a prestressed shield tunnel structure; arranging a prestressed stranded wire; s2, threading and tensioning the prestressed stranded wires in the prestressed ducts at the corresponding positions; s3, the construction position of the connecting channel between the prestressed shield tunnels is determined, the pre-construction area is reinforced firstly, then the prestressed pipe rings are partially cut, notch pipe rings are formed, and notches in the multiple sets of notch pipe rings are combined to form an opening; s4, a soil body between openings of the prestressed shield tunnel provided with the connecting channel is excavated, and a supporting structure is constructed; and S5, after supporting construction is completed, slope surface construction of the connection channel is conducted. The steel consumption can be greatly reduced, the construction cost is saved, and the construction safety and efficiency are improved.

Description

Technical Field

[0001] The invention relates to the technical field of shield tunnels, in particular to a construction method for a prestressed shield tunnel communication channel structure. Background Art

[0002] The shield tunnel communication channel is a horizontal channel set up between two subway tunnels, which plays the role of safe evacuation of passengers, tunnel drainage, fire prevention and fire fighting. According to regulations: two single-track section tunnels should have communication channels, the distance between two adjacent communication channels should not be greater than 600m, and parallel reverse-opening Class A fire doors should be set in the communication channels, and the opening of the door leaves shall not intrude into the limit.

[0003] At present, shield tunnels generally use special lining rings in the connecting passages, mainly including steel pipe segments, steel plate-covered concrete composite pipe segments, steel-concrete-fiber reinforced concrete composite pipe segments, steel pipe-fiber reinforced concrete composite pipe segments, etc. However, the above pipe segment structures have problems such as cumbersome production process, heavy weight, and difficult on-site hoisting, and more steel consumables and high cost. In addition, the existing special lining rings often need to be supported in the tunnel when broken or cut, and the tunnel structure is greatly deformed during construction.

[0004] In addition, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making the present invention, but due to space limitations, not all details and contents are listed in detail. However, this does not mean that the present invention does not have the characteristics of these prior arts. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art to the background technology. Summary of the invention

[0005] The purpose of the present invention is to provide a construction method for a prestressed shield tunnel communication channel structure to solve the problems existing in the prior art.

[0006] To achieve the above object, the present invention provides the following solution: The present invention provides a construction method of a prestressed shield tunnel communication channel structure, comprising the following steps: S1, prefabricate a predetermined number of prestressed anchor segment blocks and prestressed common segment blocks, assemble the prestressed common segment blocks and prestressed anchor segment blocks into a continuous multi-ring prestressed pipe ring in the left and right lines of the tunnel, and form a prestressed shield tunnel structure, arrange multiple prestressed channels located inside the cross section in the prestressed pipe ring, and arrange prestressed strands at predetermined positions according to design requirements; S2, threading and tensioning the prestressed strands in the prestressed duct at the corresponding position according to the design requirements, and then injecting grouting material into the tensioned prestressed duct; S3, determining the construction position of the connecting channel between the prestressed shield tunnels, first reinforcing the pre-construction area, and then cutting one side of the prestressed pipe ring according to the design requirements to form a notched pipe ring, and the notches on several groups of notched pipe rings are combined to form an opening, and the notch portion of the notched pipe ring exposes a predetermined length of prestressed stranded wire; S4, excavate the soil between the openings of the prestressed shield tunnel for setting the communication passage, and construct the supporting structure; S5: After the support construction is completed, the slope construction of the communication channel will be carried out.

[0007] According to the construction method of the prestressed shield tunnel connecting channel structure provided by the present invention, in S1, the prestressed channels of the prestressed pipe ring located within the connecting channel are injected with grouting material according to the arrangement position of the prestressed strands, and the remaining prestressed channels are used as reserved channels.

[0008] According to the construction method of the prestressed shield tunnel communication channel structure provided by the present invention, in S3, a strip-shaped waterproof groove is cut on the side close to the water-facing surface in the thickness direction of the opening, and a sealing gasket that swells when exposed to water is placed in the waterproof groove.

[0009] According to the construction method of the prestressed shield tunnel communication channel structure provided by the present invention, in S4, the communication channel is excavated by an excavator or by a mining method; When excavation is carried out using a roadheader, the supporting structure is the pipe segment; When the mining method is used for excavation, the support structure consists of an outer primary support, a middle waterproof lining and an inner secondary lining.

[0010] According to the construction method of the prestressed shield tunnel communication channel structure provided by the present invention, in S5, the slope is used for drainage, and the slope is herringbone or linear.

[0011] According to the construction method of the prestressed shield tunnel connecting channel structure provided by the present invention, in S4, a segment reinforcement area is set at the connection between the connecting channel and the slot pipe ring, and the segment reinforcement area includes a pre-embedded connecting plate and a pre-embedded anchoring system. The pre-embedded connecting plate is used to fix the uncut prestressed strands, and the pre-embedded anchoring system can re-tension the reserved un-tensioned prestressed duct after the tunnel structure reaches its service life or the structure is subjected to a large disturbance.

[0012] According to the construction method of the prestressed shield tunnel connecting channel structure provided by the present invention, the embedded anchor system is connected to the reserved un-tensioned prestressed channel, and the embedded anchor system includes a tensioning groove, a re-tensioning channel, an anchor pad, a spiral reinforcement and an anchor plate for fixing the re-tensioned prestressed stranded wire.

[0013] According to the construction method of the prestressed shield tunnel communication channel structure provided by the present invention, in S3, the surface is roughened after the opening is formed.

[0014] The present invention discloses the following technical effects: 1. The present invention forms a notched pipe ring by cutting on the prestressed pipe ring, and there is no need to design a special lining ring at the communication channel separately. On the one hand, the design cost and production cycle of the special lining ring are reduced. On the other hand, the notched pipe ring does not require additional steel reinforcement, which can greatly reduce the amount of steel and the weight of the pipe segment blocks, save production costs, and facilitate the assembly of the pipe segments.

[0015] 2. The notched pipe ring of the present invention can effectively improve the integrity, deformation resistance, toughness, ultimate bearing capacity, etc. of the tunnel structure after prestressing, reduce the deformation caused by cutting or destroying the pipe ring, and can reduce a large number of temporary support measures compared to the construction of ordinary shield tunnel connecting channels, thereby improving the structural performance of the pipe segments used in the connecting channel structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a schematic diagram of the connection channel structure of the prestressed shield tunnel in the present invention; Figure 2 For the present invention Figure 1 A schematic diagram of the structure of the AA section; Figure 3 It is a structural schematic diagram of the prestressed pipe ring in the present invention; Figure 4 It is a structural schematic diagram of the notch pipe ring in the present invention; Figure 5 It is a structural schematic diagram of the pipe ring opening in the present invention; Figure 6 It is a schematic diagram of the communication channel structure in the present invention; Figure 7 For the present invention Figure 6 Structural schematic diagram of the AA section; Figure 8 For the present invention Figure 6 A schematic structural diagram of the BB section; Fig. 9 For the present invention Figure 6 A schematic structural diagram of the CC section; Fig.10 It is a schematic diagram of the structure of the segment reinforcement area in the present invention; Fig.11 For the present invention Fig.10 A schematic diagram of the structure of the AA section; Fig.12 It is a three-dimensional numerical model of the common segment communication channel structure in the present invention; Fig.13 A three-dimensional numerical model of the prestressed segment connection channel structure in the present invention; Fig.14 The structure convergence of the common pipe segment communication channel junction and the prestressed pipe segment communication channel junction in the present invention is caused by the cutting opening; Fig.15 is the axial force of the common segment communication channel junction and the prestressed segment communication channel junction after cutting and opening in the present invention; Fig.16 It is the bending moment of the common segment connecting channel junction and the prestressed segment connecting channel junction after cutting and opening in the present invention.

[0018] Among them, 1. Prestressed anchored segment block; 2. Prestressed ordinary segment block; 3. Prestressed pipe ring; 4. Prestressed duct; 5. Notched pipe ring; 6. Reinforcement area. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Reference Figure 1-13 The present invention provides a construction method for a prestressed shield tunnel communication channel structure, comprising the following steps: S1, prefabricate a predetermined number of prestressed anchor segment blocks 1 and prestressed common segment blocks 2, and assemble them into continuous multi-ring prestressed pipe rings 3 through stressed common segment blocks and prestressed anchor segment blocks 1 in the left and right lines of the tunnel to form a prestressed shield tunnel structure. A plurality of prestressed channels 4 located inside the cross section are arranged in the prestressed pipe ring 3, and prestressed strands are arranged at predetermined positions according to design requirements; a plurality of prestressed channels 4 located at the center of the cross section are arranged in the prestressed pipe ring 3, and the prestressed channels 4 need to be embedded before the segment is cast. The material of the prestressed channels 4 can be selected from corrugated pipes, steel pipes, plastic pipes, etc., and the inner diameter needs to be adjusted according to the setting of the prestressed strands. After the prestressed pipe ring 3 is assembled, the prestressed strands are inserted from one end of the anchor groove according to design requirements, and after a circle, they are passed out from the other end of the anchor groove and tensioned; S2, threading and tensioning the prestressed strands in the prestressed duct 4 at the corresponding position according to the design requirements, and then injecting grouting material into the tensioned prestressed duct 4; The prestressed pipe ring 3 can be tensioned with a bond or without a bond. When the tensioning with a bond is selected, grouting material is injected into the prestressed channel 4 from the anchor groove after tensioning is completed. When the tensioning without a bond is selected, prestressed strands with PE are required, and no grouting is required in the prestressed channel 4 after tensioning is completed; during the construction phase, prestressed strands are only set and tensioned in part of the prestressed channels 4, and part of the prestressed channels 4 are reserved channels without tensioning. After design verification, the structural performance of the prestressed pipe ring 3 when only two prestressed channels 4 are tensioned can meet the tunnel design requirements, and the reserved multiple prestressed channels 4 are used as reserves so that tensioning can be performed when the tunnel structure reaches its service life or prestress loss occurs, so as to extend the service life of the tunnel structure; the selection of the prestressed channels 4 tensioned during the construction phase must meet the requirement that the stress distribution of the pipe ring cross section is uniform after tensioning. For example, when the tensioning number is an even number, symmetrically distributed channels are preferred, and when the tensioning number is an odd number, channels located in the middle and symmetrical on both sides are selected; The notched pipe ring 5 adopts a bonding tensioning scheme. After the prestressing tensioning is completed, grouting material needs to be injected into the prestressed channel 4. The bonding tensioning scheme can ensure that the prestressed strands are fully bonded to the prestressed channel 4, improve the safety of the prestressed system, and ensure that the uncut section can still have sufficient prestress after the prestressed strands at the opening are cut, thereby improving the structural safety performance of the notched pipe ring 5; S3, determine the construction position of the communication channel between the prestressed shield tunnels, first reinforce the pre-construction area, and then cut one side of the prestressed pipe ring 3 according to the design requirements to form a notched pipe ring 5, and the notches on several groups of notched pipe rings 5 ​​are combined to form an opening, and the notch portion of the notched pipe ring 5 exposes a predetermined length of prestressed stranded wire; The slot pipe ring 5 can be tensioned by the prestressed channels 4 that are symmetrically distributed on both sides of the pipe segment width direction, and the opening should be located in the middle of the two rings of slot pipe ring 5 to avoid the opening spanning the width direction of the slot pipe ring 5; after the slot pipe ring 5 is cut to form an opening, the prestressed channel 4 with at least one bundle of prestressed strands stretched should be kept intact, and the thickness of the concrete protective layer should be safe, the purpose is to ensure that the slot pipe ring 5 is in a prestressed state to maintain the stability and safety of the tunnel structure. For a single-hole single-line shield tunnel, the opening width is generally less than 2m, and the width of the slot pipe ring 5 with a 2-ring width of 1.5m is 3m, which meets the condition that both the 2-ring slot pipe rings 5 ​​retain at least one bundle of prestressed strands stretched. The opening of the slot pipe ring 5 can be cut into a square shape by a cutting machine, or it can be cut into a circle by a tunnel boring machine; S4, excavate the soil between the openings of the prestressed shield tunnel for setting the communication passage, and construct the supporting structure; S5: After the support construction is completed, the slope construction of the communication channel will be carried out.

[0022] In a further optimized solution, in S1, the prestressed channels 4 of the prestressed pipe ring 3 within the range of the communication channel are injected with grouting material according to the arrangement position of the prestressed strands, and the remaining prestressed channels 4 are used as reserved channels.

[0023] As a further optimization scheme, in S3, a strip-shaped waterproof groove is cut on the side of the opening thickness direction close to the water-facing surface, and a sealing gasket that swells when exposed to water is placed in the waterproof groove.

[0024] To further optimize the scheme, in S4, the communication channel is excavated by an excavator or by the mining method; When excavation is carried out using a roadheader, the supporting structure is the pipe segment; When the mining method is used for excavation, the support structure consists of an outer primary support, a middle waterproof lining and an inner secondary lining.

[0025] The secondary lining of the connecting channel comprises a lining thickening area at both ends of the channel which is thicker and closely attached to the outer surface of the slotted pipe ring 5, and a pipe segment reinforcement area 6 which is connected to the opening of the slotted pipe ring 5. The lining thickening area and the pipe segment reinforcement area 6 are an integral cast structure, which can strengthen the structural performance of the pipe ring at the opening and improve the bearing capacity and deformation resistance of the pipe ring.

[0026] In the further optimized solution, in S5, the slope is used for drainage, and the slope is herringbone or linear.

[0027] In a further optimized solution, in S4, a segment reinforcement area 6 is provided at the connection between the connecting channel and the slotted pipe ring 5. The segment reinforcement area 6 includes a pre-embedded connecting plate and a pre-embedded anchoring system. The pre-embedded connecting plate is used to fix the uncut prestressed strands. The pre-embedded anchoring system can re-tension the reserved un-tensioned prestressed duct 4 after the tunnel structure reaches its service life or the structure is subjected to a large disturbance.

[0028] To further optimize the solution, the embedded anchoring system is connected to the reserved un-tensioned prestressed channel 4, and the embedded anchoring system includes a tensioning groove, a re-tensioning channel, an anchor pad, a spiral reinforcement and an anchor plate for fixing the re-tensioned prestressed strand.

[0029] A segment reinforcement area 6 is arranged at the connection between the communication channel and the slot pipe ring 5. The segment reinforcement area 6 is provided with a pre-embedded sealing gasket, a pre-embedded anchoring system, etc., which can improve the bearing capacity and deformation resistance of the opening of the slot pipe ring 5. The pre-embedded sealing gasket can prevent groundwater from leaking into the tunnel through the connection. The pre-embedded anchoring system can re-tension the reserved prestressed channel 4, thereby effectively extending the service life of the communication channel.

[0030] The embedded connection plate is embedded in the segment reinforcement area 6 in the extension direction of the prestressed strand, and is welded or otherwise fixed to the reserved end of the prestressed strand. The embedded anchoring system includes a tensioning groove, a re-tensioning channel, an anchor pad, a spiral rib, and an anchor plate for fixing the re-tensioned prestressed strand in the extension direction of the untensioned prestressed duct 4. One end of the embedded re-tensioning channel is connected to the untensioned prestressed duct 4, and the other end is connected to the tensioning groove. An anchor pad and spiral rib are embedded at the end, and the bottom of the tensioning groove is a flat circular or square groove. After the communication channel structure reaches its service life, the untensioned prestressed duct 4 can be tensioned after the prestressed strand is inserted, and fixed by an anchor plate. As a reserved reinforcement system for the notch pipe ring 5, the embedded anchoring system can be inserted into the reserved untensioned prestressed duct 4 again to tension the prestressed strand after the tunnel structure reaches its service life or the structure is greatly disturbed. At this time, a bonding or non-bonding tensioning scheme can be selected.

[0031] In a further optimization scheme, in S3, the surface is roughened after the opening is formed.

[0032] The present invention uses MADIS FEA software to establish a three-dimensional numerical model of the common segment connecting channel structure and the prestressed segment connecting channel structure. Since the model is a symmetrical structure, only one side is established for force analysis. The thickness of the two types of segments is 300 mm, the outer diameter is 6400 mm, the width is 1200 mm, and there are 6 rings in total. The annular seams and longitudinal seams of the common segment connecting channel structure are both connected by bolts, and the longitudinal seams of the prestressed segment connecting channel structure are connected by bolts, and the longitudinal seams are connected by prestressed stranded wire. The bolts are 8.8 grade M24, and there are two bundles of prestressed stranded wire, each with an area of ​​560 mm 2 , applying prestress of 1320 MPa. All concrete is C50. The load-structure model is selected, the stratum load considers the soil pressure of twice the hole diameter, the stratum base coefficient is 40 MPa / m, and the structural load is shown in Table 1.

[0033] Table 1 Structural loads , Fig.14The structural convergence of the two types of segments due to the cutting opening is shown. The structural convergence of the prestressed segment communication channel structure due to the cutting opening is significantly smaller than that of the ordinary segment communication channel structure. At the top of the tunnel structure, the radial convergence increment of the ordinary segment communication channel structure is 16.7 mm, and that of the prestressed segment communication channel structure is 15.7 mm, and the convergence value of the prestressed segment communication channel structure is reduced by 5%. At the top of the opening, the radial convergence increment of the ordinary segment communication channel structure is 16.1 mm, and that of the prestressed segment communication channel structure is 12.9 mm, and the convergence value of the prestressed segment communication channel structure is reduced by 19.6%; below the opening, the radial convergence increment of the ordinary segment communication channel structure is 8.9 mm, and that of the prestressed segment communication channel structure is 5.5 mm, and the convergence value of the prestressed segment communication channel structure is reduced by 38.2%.

[0034] Fig.15 and Fig.16 The internal forces of the two types of segments after cutting are shown. After cutting, the maximum bending moment of both types of segments occurs in the section rotated 20° clockwise from the tunnel structure arch. The axial forces of the ordinary segment connecting channel structure and the prestressed segment connecting channel structure in this section are 1128.9kN and 2028.2kN, respectively, and the bending moments are 205.4kN·m and 284.9kN·m, respectively. Through reinforcement calculation, the minimum area of ​​the main reinforcement of the ordinary segment connecting channel structure is 2199mm², and the main reinforcement ratio is 0.61%; the minimum area of ​​the main reinforcement of the prestressed segment connecting channel structure is 1901mm², and the main reinforcement ratio is 0.53%. The reinforcement amount of the prestressed segment connecting channel structure is reduced by 13.6%, and the reinforcement amount is lower.

[0035] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0036] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A construction method for a prestressed shield tunnel communication channel structure, characterized in that: The steps include: S1, prefabricate a predetermined number of prestressed anchor segment blocks (1) and prestressed common segment blocks (2), assemble the common stress segment blocks and prestressed anchor segment blocks (1) into a continuous multi-ring prestressed tube ring (3) in the left and right lines of the tunnel, and form a prestressed shield tunnel structure, arrange a plurality of prestressed channels (4) located inside the cross section in the prestressed tube ring (3), and arrange prestressed strands at predetermined positions according to design requirements; S2, threading and tensioning the prestressed strands in the prestressed duct (4) at the corresponding position according to the design requirements, and then injecting grouting material into the tensioned prestressed duct (4); S3, determining the construction position of the communication channel between the prestressed shield tunnels, first reinforcing the pre-construction area, and then cutting one side of the prestressed pipe ring (3) according to the design requirements to form a notched pipe ring (5), wherein the notches on a plurality of groups of notched pipe rings (5) are combined to form an opening, and the notched portion of the notched pipe ring (5) exposes a predetermined length of prestressed stranded wire; S4, excavate the soil between the openings of the prestressed shield tunnel for setting the communication passage, and construct the supporting structure; S5: After the support construction is completed, the slope construction of the communication channel will be carried out.

2. The construction method of a prestressed shield tunnel communication channel structure according to claim 1, characterized in that: In S1, the prestressed holes (4) of the prestressed pipe ring (3) within the range of the communication channel are injected with grouting material according to the arrangement position of the prestressed strands, and the remaining prestressed holes (4) are used as reserved holes.

3. The construction method of a prestressed shield tunnel communication channel structure according to claim 1, characterized in that: In S3, a strip-shaped waterproof groove is cut on the side of the opening thickness direction close to the water-facing surface, and a sealing gasket that swells when exposed to water is placed in the waterproof groove.

4. The construction method of a prestressed shield tunnel communication channel structure according to claim 1, characterized in that: In S4, the communication channel is excavated by an excavator or by the mining method; When excavation is carried out using a roadheader, the supporting structure is the pipe segment; When the mining method is used for excavation, the support structure consists of an outer primary support, a middle waterproof lining and an inner secondary lining.

5. The construction method of a prestressed shield tunnel communication channel structure according to claim 1, characterized in that: In S5, the slope is used for drainage and the slope is herringbone or linear.

6. The construction method of a prestressed shield tunnel communication channel structure according to claim 1, characterized in that: In S4, a pipe segment reinforcement area (6) is provided at the connection between the connecting channel and the slot pipe ring (5), and the pipe segment reinforcement area (6) includes a pre-buried connection plate and a pre-buried anchoring system. The pre-buried connection plate is used to fix the uncut prestressed strands, and the pre-buried anchoring system can re-tension the reserved untensioned prestressed duct (4) after the tunnel structure reaches its service life or the structure is subjected to a significant disturbance.

7. The construction method of a prestressed shield tunnel communication channel structure according to claim 6, characterized in that: The pre-buried anchoring system is connected to the reserved un-tensioned prestressed duct (4), and the pre-buried anchoring system comprises a tensioning groove, a re-tensioning duct, an anchor pad, a spiral reinforcement, and an anchor plate for fixing the re-tensioned prestressed strand.

8. The construction method of a prestressed shield tunnel communication channel structure according to claim 1, characterized in that: In S3, the surface is roughened after the opening is formed.

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