A TBM or shield tunnel segment tensioning device and installation method

Abstract

The present invention discloses a tensioning device and construction method for TBM or shield tunnel segments, including precast concrete segments, sub-connecting blocks, mother-connecting blocks, first steel strands and second steel strands; a tensioning space is provided at the central position of the precast concrete segment, a sub-connecting block reserved groove is arranged on one side of the tensioning space, a mother-connecting block reserved groove is arranged on one side of the tensioning space, and both the sub-connecting block reserved groove and the mother-connecting block reserved groove communicate with the tensioning space through steel strand holes; the sub-connecting block is arranged in the sub-connecting block reserved groove, the mother-connecting block is arranged in the mother-connecting block reserved groove, the sub-connecting block of adjacent precast concrete segments is connected to the mother-connecting block, and one end of the first steel strand passes through the sub-connecting block and is fixedly connected in the tensioning space of one of the precast concrete segments, the other end of the first steel strand is connected to one end of the second steel strand, and the other end of the second steel strand passes through the mother-connecting block and is fixedly connected in the tensioning space of another precast concrete segment after being tensioned by a tensioning device.

Description

Technical Field

[0001] The invention belongs to the field of rail transit engineering, and particularly relates to a tensioning device and installation method for segments of a TBM or shield tunnel. Background Art

[0002] In shield or TBM tunnels, precast concrete segments are mostly used for support. The connection of precast concrete segments at the tunnel entrance / exit and connecting passage is prone to looseness. Moreover, during construction in soft strata, the restraint on the segments is weak, and they are prone to looseness after being disturbed, resulting in problems such as segment misalignment and the sealing gasket between segments not being able to fit tightly with the segments.

[0003] Currently, the tensioning device for shield tunnels mechanically tensions with steel strands or threaded steel on the inner side of the tunnel. This tensioning method will make the joint on the side where the segment is close to the surrounding rock larger, and it cannot achieve a good tensioning effect. There will be an angular offset between the tensioned segment and the adjacent non-tensioned segment. In addition, there is also a method of tensioning in the middle of the segment using shear pins and embedded parts. Due to the short length of the shear pins and the absence of an anchorage section, this method cannot achieve a good bending resistance effect, and bolts need to be further increased, resulting in complex assembly. Summary of the Invention

[0004] In order to overcome the above-mentioned deficiencies, the present invention provides a tensioning device and installation method for segments of a TBM or shield tunnel, aiming to solve problems such as the insufficient connection density between segments at the tunnel entrance / exit, connecting passage and soft strata of the shield tunnel, and the weak bending and shear resistance of the segment circumferential joints.

[0005] To achieve the above object, the present invention is realized through the following technical solutions:

[0006] In the first aspect, the tensioning device for segments of a TBM or shield tunnel provided by the embodiment of the present invention includes precast concrete segments, sub-connection blocks, mother-connection blocks, a first steel strand, and a second steel strand;

[0007] Along the axial direction of the precast concrete segment, a tensioning space is provided at the central position of the precast concrete segment. A sub-connection block reserved groove is arranged on one side of the tensioning space, and a mother-connection block reserved groove is arranged on one side of the tensioning space. Both the sub-connection block reserved groove and the mother-connection block reserved groove are communicated with the tensioning space through steel strand holes; the sub-connection block is arranged in the sub-connection block reserved groove, the mother-connection block is arranged in the mother-connection block reserved groove, the sub-connection block of adjacent precast concrete segments is connected to the mother-connection block, and one end of the first steel strand passes through the sub-connection block and is fixedly connected in the tensioning space of one of the precast concrete segments. The other end of the first steel strand is connected to one end of the second steel strand, and the other end of the second steel strand passes through the mother-connection block and is fixedly connected in the tensioning space of another precast concrete segment after being tensioned by a tensioning device.

[0008] As a further technical solution, adjacent precast concrete segments are connected by two sets of tensioning components arranged vertically.

[0009] As a further technical solution, adjacent sub-connecting blocks and mother-connecting blocks are connected by protrusions and grooves.

[0010] As a further technical solution, adjacent sub-connecting blocks and mother-connecting blocks are connected by threads.

[0011] As a further technical solution, both the sub-connecting block and the mother-connecting block are conical, and the taper of the reserved groove of the sub-connecting block is the same as that of the sub-connecting block; the taper of the reserved groove of the mother-connecting block is the same as that of the mother-connecting block.

[0012] As a further technical solution, one end of the first steel strand is fixedly connected to a connecting nut, and the other end is provided with a threaded steel bar, on which a fastening nut and a tensioning backing plate are arranged.

[0013] As a further technical solution, the tensioning backing plate is provided with a grouting hole.

[0014] As a further technical solution, both ends of the second steel strand are provided with threaded steel bars. One end is used to connect with the first steel strand, and the other end is provided with a tensioning backing plate and a fastening nut. The axial force gauge is sleeved on the non-threaded section in the middle of the second steel strand.

[0015] As a further technical solution, the tensioning backing plate is provided with a grouting hole.

[0016] In the second aspect, the present invention also provides a construction method for a TBM or shield tunnel segment tensioning device, as follows:

[0017] Manufacture precast concrete segments;

[0018] Put the sub-connecting block and the mother-connecting block into the reserved grooves of the precast concrete segments respectively. Pass the steel strand of the first tensioning device through the sub-connecting block, and pass the steel strand of the second tensioning device through the mother-connecting block;

[0019] First install the first-ring precast concrete segment. After this ring of precast concrete segment is fixed, install the next ring of precast concrete segment. Before the next ring of precast concrete segment is fixed, use the connecting nut to connect the first steel strand and the second steel strand to make the sub- and mother-connecting blocks between the segment rings nested; after the segment is installed in place, in the tensioning space, install the tensioning backing plate and the fastening nut on the steel strand on one side of the mother-connecting block, tension the steel strand on one side of the sub-connecting block, observe the data of the axial force gauge of the second steel strand, and after achieving the tensioning effect, tighten the fastening nut on one side of the tensioning backing plate to complete the prestress application;

[0020] After the prestress is applied, the tensioning device used to apply the tensile force is removed in sequence. The reserved groove inside the connecting block and the steel strand hole are sealed and grouted through the grouting hole of the tensioning backing plate. After the grouting is completed, it is sealed with a gasket adapted to the grouting hole, and the segment installation is completed.

[0021] The beneficial effects of the above embodiments of the present invention are as follows:

[0022] In this device, the male and female connecting blocks can increase the shear and bending resistance between segment rings and improve the integrity of segment connection. After the segment prestress is tightened using this device, the restraint effect between segments is strengthened. The prestress tightening of this device is carried out inside the segment, which will not cause angular deviation between the tensioned segment and the untensioned segment. After tensioning, the waterproof sealing gasket between segments can be closely attached, reducing the occurrence of water leakage. Sealing and grouting the reserved groove of the connecting block and the steel strand hole can greatly reduce the prestress loss and delay the prestress attenuation. After this device is installed, there is no need to install shear pins and connecting bolts, and the operation is simple and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0024] Figure 1 It is a three-dimensional structure schematic diagram of the precast concrete segment proposed by the present invention;

[0025] Figure 2 It is a two-dimensional structure schematic diagram of the precast concrete segment proposed by the present invention;

[0026] Figure 3 It is a structure schematic diagram of the female connecting block in the present invention;

[0027] Figure 4 It is a structure schematic diagram of the male connecting block in the present invention;

[0028] Figure 5 It is a schematic diagram of the connection state between the segment and the tensioning device proposed by the present invention;

[0029] Figure 6 It is a schematic diagram of the cooperation state of the No. 1 steel strand and the tensioning device;

[0030] Figure 7 It is a schematic diagram of the cooperation state of the No. 2 steel strand and the connecting piece;

[0031] In the figure: The distances or dimensions between each part are exaggerated for showing the positions of each part, and the schematic diagram is only for illustration.

[0032] 1 - Connecting block reserved groove, 2 - Tensioning space, 3 - Strand hole, 4 - Female connecting block, 5 - Male connecting block, 6 - Tensioning device, 7 - Annular rubber gasket, 8 - No. 1 strand, 9 - Fastening nut, 10 - Jack backing plate, 11 - Tensioning jack, 12 - Jack support frame, 13 - Tensioning backing plate, 14 - Tensioning backing plate grouting hole, 15 - Connecting nut, 16 - Axial force gauge, 17 - No. 2 strand. Detailed implementation mode

[0033] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0034] It should be noted that the terms used herein are only for describing specific implementation modes and are not intended to limit the exemplary implementation modes of the present invention. As used herein, unless the present invention clearly states otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof;

[0035] For the convenience of narration, if the words "upper", "lower", "left", and "right" appear in the present invention, they only indicate the same direction as the upper, lower, left, and right directions of the attached drawings themselves, and do not limit the structure. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0036] Term explanation part: The terms "installation", "connection", "connection", "fixation", etc. in the present invention should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection or an electrical connection, it can be a direct connection or an indirect connection through an intermediate medium, it can be an internal connection between two elements, or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] As introduced in the background technology, there are deficiencies in the prior art. In order to facilitate the tightening and close fitting of the segments, make the waterproof seal better play its role, and increase the bending and shear resistance of the segment circumferential joint, a segment tightening device with good bending and shear resistance effects is proposed, which can cancel the segment connection bolts and shear pins, and the operation is simple and convenient.

[0038] In a typical embodiment of the present invention, the tensioning device proposed in this embodiment is arranged at the entrance and exit of the TBM / shield tunnel, the connecting passage and the soft stratum. This device is composed of precast concrete segments, connecting blocks, tensioning devices, etc.

[0039] The connecting block is divided into two parts, namely a protruding part and a recessed part. Here, the protruding part is called the sub-connecting block, and the recessed part is called the mother-connecting block. The connecting block is long conical in shape and can play a role in shear resistance and bending resistance when installed in the segment. The segments required for this device are precast concrete segments, with tensioning spaces, connecting block reserved grooves and steel strand holes left at the upper and lower parts of the segments. The connecting block reserved grooves and steel strand holes penetrate the inside of the segments.

[0040] Before installing the precast special segment, put the mother and son connecting blocks into the reserved grooves of the special precast segment connecting blocks. Further, pass the steel strands through the sub (mother) connecting blocks and the steel strand holes and extend them into the tensioning space. The sub-connecting block is pasted with an annular gasket to prevent the slurry from leaking at the interface. When installing the segments, first install the ring of segments containing the mother-connecting block. After this ring of segments is fixed, install the segments containing the sub-connecting block. When installing each segment, first connect the steel strands of the two sides of the segment with the connecting nuts of the steel strands, and then install the segments containing the sub-connecting block to nest the mother and son connecting blocks to play a role in shear resistance and bending resistance.

[0041] After the segment assembly is completed, fix the end of the steel strand on one side of the sub-connecting block in the tensioning space. When fixing, first install the tensioning backing plate and then install the fastening nut. Further, pass the steel strands on one side of the mother-connecting block through the tensioning backing plate, fastening nut, jack support frame, jack, jack backing plate, and fastening nut in sequence in the tensioning space. Further, apply prestress with two jacks. After reaching the tensioning stress, tighten the inner fastening nut. After the prestress application is completed, remove the outer fastening nut, jack backing plate, jack, and jack support frame in sequence, and perform grouting to seal the inside of the connecting block reserved groove and the steel strand hole through the grouting hole of the tensioning backing plate. After the grouting is completed, seal it with a gasket adapted to the grouting hole to retain the tensioning prestress to a greater extent and achieve close fitting between the segments. Observe the data of the axial force gauge. After achieving the tensioning effect, block the tensioning space with concrete to complete the segment installation.

[0042] The structure of the precast concrete segment disclosed in this embodiment is as Figure 1 , Figure 2 shown. The segment is a precast concrete segment, and tensioning spaces 2, connecting block reserved grooves 1 and steel strand holes 3 are left at both the upper and lower parts of the segment, as Figure 2As shown in the figure, the tensioning space 2 is located at the center of the segment. Connecting block reserved grooves 1 are provided on both the left and right sides of the tensioning space 2. The connecting block reserved grooves 1 on the right and left sides are respectively communicated with the middle tensioning space 2 through steel strand holes 3. The connecting block reserved grooves and the steel strand holes penetrate through the interior of the segment. Moreover, the tensioning space 2, the connecting block reserved grooves 1, and the steel strand holes 3 in the upper part of the segment are symmetrically arranged with the tensioning space 2, the connecting block reserved grooves 1, and the steel strand holes 3 in the lower part of the segment. In this embodiment, prestress is applied in the tensioning space and grouting is carried out in the steel strand holes.

[0043] This embodiment discloses two connecting blocks. As Figure 3 , Figure 4 shown, Figure 3 is the female connecting block, Figure 4 is the male connecting block. The female connecting block 4 is conical, and a groove is provided at its large-diameter end. The male connecting block 5 is also conical, and a protrusion is provided at its large-diameter end. The groove and the protrusion are exactly matched together to realize the connection between the two; moreover, the taper of the female connecting block 4 and the male connecting block 5 is the same as the taper of the connecting block reserved groove 1.

[0044] After the circumferential joints of the shield segments are spliced, due to reasons such as surrounding rock pressure and the self-weight of the segments, misalignment will occur between adjacent segments. In order to make the structure more stable, the segment splicing more tight, and increase the shear and bending resistance of the overall segments. Place the two connecting blocks at the segment joint. The male connecting block and the female connecting block are respectively placed in the connecting block reserved grooves on the left and right sides of the segment. The male connecting block and the female connecting block are nested with each other, and a sealing gasket is pasted on one side of the male connecting block. The male and female connecting blocks are designed to be long conical. After installation, they can play a role in resisting bending and shear, and can greatly improve the stability of the segments.

[0045] It should be further noted that the male and female connecting blocks in this embodiment can be changed from nesting to threaded connection. When connecting two adjacent rings of segments, use steel strands to pass through the reserved holes of the male and female connecting blocks, and further screw the male connecting block into the female connecting block, and then further carry out the assembly of the remaining segments and the prestress application and concrete slurry grouting.

[0046] The schematic diagram of the cooperation state between the tensioning device and the steel strands disclosed in this embodiment is as Figure 6 , Figure 7 shown. In this embodiment, there are two types of tensioning devices. One of the tensioning devices is as Figure 6As shown in the figure, it includes strand 8 of steel No. 1, fastening nut 9 on the right side of the left end of strand 8 of steel No. 1, tensioning backing plate 13, tensioning backing plate grouting hole 14, and connecting nut 15. Among them, jack backing plate 10, tensioning jack 11, jack support frame 12, and the leftmost fastening nut 9 are used to apply pre-tightening force and will be removed later. The right end of strand 8 of steel No. 1 is fixedly connected with connecting nut 15, and this connecting nut 15 is connected with the threaded steel bar at the end of strand 2 of steel. The left end of strand 8 of steel No. 1 is provided with a threaded steel bar. Jack support frame 12 and jack backing plate 10 are sleeved on this threaded end, and the two are connected by jack 11. Fastening nut 9 is installed on the left side of jack backing plate 10, and another fastening nut 9 is installed on the right end of jack support frame 12. Tensioning backing plate 13 is installed on the right side of fastening nut 9. Tensioning backing plate 13 is provided with tensioning backing plate grouting hole 14. A grouting hole is reserved inside the tensioning backing plate. After the prestress is applied, the steel strand hole and the gap of the connecting block can be filled with grout to retain the tension prestress to a greater extent.

[0047] Another kind of steel strand is as Figure 7 shown, including fastening nut 9, tensioning backing plate 13, backing plate grouting hole 14, load cell 16, and strand 17 of steel No. 2. The left end and the right end of strand 17 of steel No. 2 are both threaded steel bars. Tensioning backing plate 13 and fastening nut 9 are installed on the left threaded end and are fixed in the corresponding tensioning space 2 later. The threaded steel bar at the right end of strand 17 of steel No. 2 is connected with the above-mentioned connecting nut 15 to realize the connection between the two steel strands. Load cell 16 is sleeved on the non-threaded section in the middle of strand 17 of steel No. 2.

[0048] As Figure 5 shown, in the tensioning space disclosed in this embodiment, the steel strand (strand 17 of steel No. 2) on one side of sub-connecting block 5 is directly installed with tensioning backing plate 13 and fastening nut 9 and then fixed in the tensioning space, and then connected with strand 8 of steel No. 1. Strand 8 of steel No. 1 passes through mother connecting block 4 and is tensioned by a tensioning device (such as Figure 6 the device shown). During tensioning, the steel strand passes through the tensioning backing plate, fastening nut, jack support frame, jack, jack backing plate, and fastening nut in sequence. Two jacks are used to apply prestress. The tensioning degree is determined according to the reading of the load cell. After tensioning is completed, tighten the fastening nut on one side of the tensioning backing plate to complete the prestress application.

[0049] Furthermore, for the above-mentioned Figure 6 shown tensioning device, the jack support frame, jack, and jack backing plate can also be removed, and the fastening nut is manually turned by a torque wrench in the tensioning space to tension the segment.

[0050] The specific implementation method of the tunnel tightening device is as follows:

[0051] When constructing in the section of the shield tunnel connection passage, this device has the characteristics of good tensioning effect and improving the shear and bending resistance between segment rings compared with traditional tensioning equipment. The overall construction process is as follows:

[0052] (1) Prefabricated concrete segments

[0053] The prefabricated concrete segments are reserved with tapered grooves, tensioning spaces and steel strand holes. Tensioning spaces, connecting block reserved grooves and steel strand holes are left at the upper and lower parts of the segments, and the connecting block reserved grooves and steel strand holes penetrate the inside of the segments.

[0054] (2) Before installing the segments

[0055] Before installing the prefabricated special segments, the male and female connecting blocks are respectively placed into the reserved holes of the special segments. Further, the steel strands pass through the male (female) connecting blocks and extend into the tensioning space through the steel strand holes. The steel strand connectors are connected to the steel strands, and the male connecting block is pasted with an annular gasket.

[0056] (3) When installing the segments

[0057] First, install the first ring of special segments. After this ring of segments is fixed, further install the next ring of segments. Before this ring of segments is fixed, connect the steel strands of the two special segments with connecting nuts. Further, nest the male and female connecting blocks between the segment rings.

[0058] (4) After the segments are installed in place

[0059] After the segments are installed in place, in the tensioning space, install the tensioning pads and fastening nuts on the steel strands on one side of the male connecting block, and tension the steel strands on the side of the female connecting block with a tensioning device. When tensioning, the steel strands pass through the tensioning pads, fastening nuts, jack supports, jacks, jack pads, and fastening nuts in sequence. Apply prestress with two jacks, determine the tensioning degree according to the reading of the axial force gauge, and after tensioning, tighten the fastening nut on one side of the tensioning pad to complete the application of prestress.

[0060] (5) Grouting for sealing

[0061] After the prestress is applied, remove the outer fastening nuts, jack pads, jacks, and jack supports in sequence. Through the grouting hole of the tensioning pad, conduct grouting for sealing inside the connecting block reserved groove and the steel strand hole. After grouting, seal it with a gasket adapted to the grouting hole to retain the tension prestress to the greatest extent and achieve close fitting between the segments. Observe the data of the axial force gauge. After achieving the tensioning effect, block the tensioning space with concrete to complete the installation of the segments.

[0062] This embodiment provides a tensioning device and installation method for segment lining of shield tunnels. Its main structural components are divided into the following three parts. The first part is precast concrete segments. Tensioning spaces, connection block reserved grooves, and steel strand holes are provided at the upper and lower parts of the segments, and the connection block reserved grooves and steel strand holes penetrate the interior of the segments. The second part is a long conical connection block. The connection block is divided into two parts, namely a protruding part and a recessed part. The protruding part is the sub-connection block, and the recessed part is the mother-connection block. The mother and sub-connection blocks are nested with each other to achieve the shear and bending resistance between rings. The third part is a tensioning device, which is composed of a tensioning backing plate, a fastening nut, a jack support frame, a jack, a jack backing plate, an axial force gauge, etc., and is used to tension two adjacent rings of segments and apply prestress. In this device, the combined action of the long conical connection block and the tensioning device enhances the integrity and stability of the precast concrete segments at the tunnel entrance and exit and the connection passage, and solves the problems of loosening at the segment joints and the inability of the segment gaskets to fit tightly with the segments.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A tensioning device for segment of TBM or shield tunnel, characterized in that, It includes precast concrete segments, sub-connecting blocks, mother-connecting blocks, the first steel strand and the second steel strand; Along the axial direction of the precast concrete segment, a tensioning space is provided at the central position of the precast concrete segment. A sub-connecting block reserved groove is arranged on one side of the tensioning space, and a mother-connecting block reserved groove is arranged on one side of the tensioning space. Both the sub-connecting block reserved groove and the mother-connecting block reserved groove communicate with the tensioning space through steel strand holes; the sub-connecting block is arranged in the sub-connecting block reserved groove, the mother-connecting block is arranged in the mother-connecting block reserved groove, the sub-connecting blocks and mother-connecting blocks of adjacent precast concrete segments are connected, and one end of the first steel strand passes through the sub-connecting block and is fixedly connected in the tensioning space of one of the precast concrete segments. The other end of the first steel strand is connected to one end of the second steel strand, and the other end of the second steel strand passes through the mother-connecting block and is fixedly connected in the tensioning space of another precast concrete segment after being tensioned by a tensioning device; Connecting block reserved grooves are arranged on both the left and right sides of the tensioning space. The connecting block reserved grooves on the left and right sides respectively communicate with the middle tensioning space through steel strand holes. The connecting block reserved grooves and the steel strand holes penetrate through the inside of the segment. And the tensioning space, the connecting block reserved grooves and the steel strand holes in the upper part of the segment are symmetrically arranged with the tensioning space, the connecting block reserved grooves and the steel strand holes in the lower part of the segment up and down; One end of the first steel strand is fixedly connected with a connecting nut, and the other end is provided with a threaded steel bar. A fastening nut and a tensioning backing plate are arranged on the threaded steel bar; Both ends of the second steel strand are provided with threaded steel bars. One end is used to be connected with the first steel strand, and the other end is provided with a tensioning backing plate and a fastening nut. An axial force gauge is sleeved on the non-threaded section in the middle of the second steel strand.

2. The TBM or shield tunnel segment tensioning device according to claim 1, characterized in that, Adjacent precast concrete segments are connected by two groups of tensioning components arranged up and down.

3. The TBM or shield tunnel segment tensioning device according to claim 1, characterized in that Adjacent sub-connecting blocks and mother-connecting blocks are connected by protrusions and grooves.

4. The TBM or shield tunnel segment tensioning device according to claim 1, characterized in that, Adjacent sub-connecting blocks and mother-connecting blocks are connected by threads.

5. The TBM or shield tunnel segment tensioning device according to claim 1, characterized in that, The sub-connecting blocks and the mother-connecting blocks are both conical. The taper of the sub-connecting block reserved groove is the same as that of the sub-connecting block; the taper of the mother-connecting block reserved groove is the same as that of the mother-connecting block.

6. The TBM or shield tunnel segment tensioning device according to claim 1, characterized in that, The tensioning backing plate is provided with grouting holes.

7. The construction method of the TBM or shield tunnel segment tensioning device according to any one of claims 1-6, characterized in that, Manufacture precast concrete segments; Put the sub-connecting blocks and the mother-connecting blocks into the reserved grooves of the precast concrete segments respectively. Pass the steel strand of the first tensioning device through the sub-connecting block, and pass the steel strand of the second tensioning device through the mother-connecting block; Install the first ring of precast concrete segments first. After this ring of precast concrete segments is fixed, install the next ring of precast concrete segments. Before the next ring of precast concrete segments is fixed, use the connecting nut to connect the first steel strand and the second steel strand to make the sub- and mother-connecting blocks between the segment rings nested; after the segments are installed in place, in the tensioning space, install the tensioning backing plate and the fastening nut on the steel strand on the side of the mother-connecting block, tension the steel strand on the side of the sub-connecting block, observe the data of the axial force gauge of the second steel strand, and after achieving the tensioning effect, tighten the fastening nut on the side of the tensioning backing plate to complete the prestress application; After the prestress is applied, the tensioning device used for applying the tensile force is removed in sequence. The reserved groove inside the connection block and the steel strand holes are sealed and grouted through the grouting holes of the tensioning backing plate. After the grouting is completed, it is sealed with a gasket adapted to the grouting hole, and the segment installation is completed.

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