Small TBM (pipe jacking) prestress back-leaning structure and construction method thereof

Abstract

The invention relates to the technical field of pipe jacking engineering, in particular to a pipe jacking prestress back leaning structure and a construction method thereof. A pipe jacking prestress back leaning structure comprises a back leaning wall, the back leaning wall is of a reinforced concrete structure and used for being arranged outside a preset starting end of a pipe jacking tunnel, the first side face of the back leaning wall faces the preset starting end, the plane where the first side face is located is perpendicular to the axis of the preset starting end, and the second side face of the back leaning wall is back to the preset starting end; the distance between the first side surface and the second side surface is gradually reduced from bottom to top; and the anchor cable is a prestressed steel beam, one end of the anchor cable penetrates through the rear wall, and the other end of the anchor cable extends into the slope where the preset starting end is located. The device overcomes the defects that in the prior art, when a construction site is limited, a starting well is difficult to build, and pushing counter force cannot be provided for jacking construction of the pipe jacking machine.

Description

Technical Field

[0001] The invention relates to the technical field of pipe jacking engineering, and in particular to a small TBM (pipe jacking) prestressed backing structure and a construction method thereof. Background Art

[0002] With the sustained and stable economic growth, pipe jacking technology has also developed rapidly in line with the times. Pipe jacking and dark excavation technology has gradually been applied to the construction of underground projects such as street crossings, subway entrances and exits, underground integrated pipe galleries, vehicle tunnels, subway stations, underground commercial streets, etc. At present, the application of this technology in the development of shallow underground space in cities in my country has received more and more attention and attention. When the pipe jacking machine is working, the pipe jacking machine and the jack are installed in the working well, and the thrust provided by the jack is used to push the pipe jacking machine and the new pipeline into the ground section by section, and the excavated soil is discharged from the ground through the excavation system. This process is repeated until the entire pipeline is laid.

[0003] In fact, not all pipe jacking projects have the conditions for building a working shaft. For example, in prosperous urban areas, due to the densely populated buildings (structures), the construction site is small and limited. When crossing the high embankments of municipal roads, highways, railways and other structures, the burying depth of the pipe is too small, and there is very little soil behind it. It is difficult to build a starting shaft if there is an existing foundation pit or basement of a building (structure). There is no structure to support the jack and it cannot provide a pushing reaction force for the jacking construction of the pipe jacking machine. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art that when the construction site is limited, it is difficult to build a starting well and cannot provide a pushing reaction force for the jacking construction of a pipe jacking machine, and to provide a small TBM (pipe jacking) prestressed back-supporting structure and a construction method thereof.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a prestressed backrest structure for a jacking pipe, comprising:

[0007] A rear wall, which is a reinforced concrete structure and is used to be arranged outside the predetermined starting end of the jacking tunnel, wherein a first side surface of the rear wall faces the predetermined starting end, a plane where the first side surface is located is perpendicular to the axis of the predetermined starting end, a second side surface of the rear wall faces away from the predetermined starting end, and a distance between the first side surface and the second side surface gradually decreases from bottom to top;

[0008] Anchor cable: The anchor cable is a prestressed steel bundle. One end of the anchor cable passes through the rear wall, and the other end extends into the slope where the predetermined starting end is located.

[0009] If a back wall is set outside the starting end, the back wall can provide recoil force to the jack of the jacking machine, so that the jacking machine receives enough recoil force to move forward. The back wall is a reinforced concrete structure with excellent concrete compression performance. It can ensure the rigidity and strength of the back wall as much as possible, and can withstand the reaction force of the jack as much as possible without being damaged. The first side is perpendicular to the axis of the starting end, so the eccentricity of the pressure of the back wall on the jack can be avoided as much as possible, which affects the accuracy of jacking and thus affects the quality of the jacking tunnel. The distance between the second side and the second side gradually decreases from bottom to top, and the second side is an inclined surface, which enhances the strength of the back wall. One end of the anchor cable passes through the back wall, and the other end is anchored to the slope where the predetermined starting end is located. The anchor cable is a prestressed steel bundle, which can increase the force of the back wall toward the predetermined starting end and avoid the device being damaged by the reaction force of the jack as much as possible.

[0010] Preferably, it also includes a stress dispersion component, which is connected to the second side of the rear wall, and the contact area between the stress dispersion component and the second side is larger than the cross-sectional area of ​​the anchor cable, and the anchor cable is anchored to the rear wall through the stress dispersion component.

[0011] The stress dispersion member can be a steel plate or a lattice structure. Because the anchor cable needs to pass through the rear wall, and the anchor cable is a prestressed component, a stress dispersion member is provided, and the contact area between the stress dispersion member and the second section is larger than the cross-sectional area of ​​the cable anchor, so that the retraction force of the anchor cable can be evenly transmitted to the rear wall through the stress dispersion member, and the stress concentration at the anchoring point of the cable anchor can be avoided as much as possible, which is beneficial to protecting the structural integrity of the rear wall.

[0012] Preferably, the stress dispersing member is a lattice structure, and the anchor cable passes through the intersection of the lattice structure and is anchored to the rear wall.

[0013] The anchor cable passes through the intersection of the lattice and is connected to the rear wall, which can not only better disperse the stress and reduce local stress concentration, but also the intersection has higher local strength and can better withstand the tension of the anchor cable.

[0014] Preferably, the anchor cables include a plurality of anchor guide tubes corresponding to the number of anchor cables are provided against the rear wall, the plurality of anchor guide tubes are symmetrically arranged along the vertical center line of the second side surface, the plurality of anchor guide tubes are spaced apart along the height direction of the rear wall, and the angle between the anchor cables and the horizontal direction gradually increases from top to bottom.

[0015] The anchor guide tubes are arranged symmetrically along the vertical center line of the second side surface. When the jack applies pressure to the rear wall, uneven force on both ends of the rear wall is avoided as much as possible, thereby avoiding damage to the rear wall as much as possible, which is conducive to extending the service life of the rear wall. The angle between the anchor cable and the horizontal direction gradually increases from top to bottom, and the spacing between the two anchor cables of the box girder is increased as much as possible to avoid the group anchor effect caused by too small cable anchor spacing, which reduces the bearing capacity of a single cable anchor.

[0016] In a second aspect, the present invention provides a construction method of a prestressed back-support structure, which is used to construct the above-mentioned prestressed back-support structure for a jacking pipe, and comprises the following steps:

[0017] S1. The steel bars against the rear wall are arranged at the predetermined position, and a template is arranged outside the steel bars against the rear wall; anchor holes for anchoring cables are drilled at the slope where the predetermined starting end is located;

[0018] S2, put one end of the anchor cable into the anchor hole and inject grout into the anchor hole; pass the other end of the anchor cable through the steel bar against the wall and cover it with a protective tube, the length of the protective tube matches the distance between the first side surface and the second side surface, and fix the anchor cable;

[0019] S3, after pouring, against the wall;

[0020] S4. After the concrete strength of the rear wall reaches 80% of the design value, the anchor cables are tensioned and locked to complete the construction of the jacking pipe prestressed rear structure.

[0021] In step S1, anchor holes are drilled, and in step S2, one end of the anchor cable is anchored and grouting is injected into the anchor hole, and the other end passes through the steel bars of the rear wall and is covered with a protective sleeve. When pouring the rear wall, the disturbance to the anchor cable can be reduced as much as possible, so as to avoid adverse effects on the quality of the anchor cable and the rear wall during subsequent tensioning. Tensioning the anchor cable can increase the force toward the predetermined starting end of the rear wall, and avoid the situation where the device is damaged by the reaction force of the jack as much as possible. When pouring the rear wall, the anchor cable is tensioned again, so that the resilience of the anchor cable is transmitted more evenly to the rear wall as much as possible. This construction method can provide the rear wall for the pipe jacking machine while minimizing the interference with the construction of the pipe jacking machine, and avoid the deviation of the actual constructed pipe jacking tunnel compared with the designed pipe jacking tunnel as much as possible.

[0022] Preferably, step S3 further comprises backfilling a jacking area between the rear wall and the predetermined starting end, wherein the top surface of the jacking area is higher than the jacking platform.

[0023] In order to ensure the structural stability of the rear wall as much as possible, the bottom surface of the rear wall is lower than the bottom of the predetermined starting end. The jacking area is backfilled in front of the rear wall, and the top surface of the jacking area is higher than the jacking platform to avoid affecting the work of the jacking machine.

[0024] Preferably, step S1 further comprises arranging a stress dispersion component on a second side surface that is against the rear wall; in step S2, one end of the anchor cable is fixed to a side of the stress dispersion component that is away from the second side surface through an anchor pad.

[0025] The anchor cable is anchored to the stress dispersion member to avoid stress concentration as much as possible.

[0026] Preferably, step S4 comprises the following steps:

[0027] S41. Pre-tension the anchor cables of each hole according to 0.1Nt to 0.2Nt, where Nt is the design value of the axial tension of the anchor cables after tensioning;

[0028] S42, tension the anchor cable in each hole three times at 0.7Nt;

[0029] S43, tension the anchor cable in each hole twice at 0.4Nt;

[0030] S44, loosen the anchor cable, and when the tension of the anchor cable is detected to be Nt, grouting is performed in the gap between the anchor cable and the grouting blind hole, and the slurry strength of the grouting is measured. When the slurry strength of the grouting is greater than or equal to 15MPa, lock the anchor cable.

[0031] Preferably, after step S4, the following steps are further included:

[0032] S5. A guide rail is arranged above the jacking area along the axis of the predetermined starting end, the guide rail is used for the advancement of the pipe jacking machine, a back steel plate is arranged on the first side of the rear wall, a jack bracket is arranged on the side of the back steel plate facing the predetermined starting end, and a jack is installed;

[0033] S6. The pipe jacking machine pushes the pipe through the jack.

[0034] Because the reaction force of the jack will act on the first side of the rear wall, but the action area of ​​the jack is limited, which will cause stress concentration on the rear wall and easily damage the rear wall structure. Therefore, a back steel plate is provided, and the jack bracket is connected to the back steel plate, so that the force applied by the jack to the rear wall can be applied to the rear wall as evenly as possible through the back steel plate, thereby reducing stress concentration as much as possible and protecting the structural integrity of the rear wall.

[0035] Preferably, in step S1, anchor holes are drilled in the slope by using a soil drill.

[0036] Compared with the water drilling method, the soil drilling method can avoid the occurrence of hole collapse as much as possible.

[0037] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0038] 1. A prestressed back-support structure for a jacking pipe of the present invention comprises a back-support wall and an anchor cable. The back-support wall is arranged outside the starting end, and the first side surface of the back-support wall facing the starting end is perpendicular to the axis of the starting end, so as to avoid as much as possible the eccentricity of the pressure of the back-support wall on the jack, which affects the precision of the jacking and thus affects the quality of the jacking pipe tunnel; the back-support wall is a reinforced concrete structure, and the concrete has excellent compressive performance, which can ensure the rigidity and strength of the back-support wall as much as possible, and can withstand the reaction force of the jack as much as possible without being damaged; the second side surface is an inclined surface, which can enhance the strength of the back-support wall; one end of the anchor cable passes through the back-support wall, and the other end is anchored to the slope where the predetermined starting end is located, and the anchor cable is a prestressed steel bundle, which can increase the force of the back-support wall toward the predetermined starting end, and avoid as much as possible the situation that the device is damaged by the reaction force of the jack. This device overcomes the shortcomings of the prior art that when the construction site is limited, it is difficult to build a starting shaft, and it cannot provide a jacking reaction force for the jacking construction of the jacking machine.

[0039] 2. A construction method of a prestressed back-support structure, used for constructing the above-mentioned prestressed back-support structure for a jacking pipe, first set the steel bars and formwork for the back-support wall, and drill anchor holes in the slope, anchor cables, one end of the anchor cables is respectively set in the anchor holes, and the other end is set with steel bars passing through the back-support wall, the back-support wall is cast, and when the strength of the back-support wall reaches 80% of the design value, the anchor cables are tensioned and locked again to complete the construction of the prestressed back-support structure for the jacking pipe. This construction method can provide a back-support wall for the jacking machine while minimizing the interference with the construction of the jacking machine, and avoid the deviation of the jacking tunnel actually constructed compared with the designed jacking tunnel as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the position of a prestressed back-support structure of a jacking pipe of the present invention;

[0041] Figure 2 It is a structural schematic diagram of the second side surface of the present invention which is against the rear wall;

[0042] Figure 3 is a schematic diagram of the lattice structure of the present invention;

[0043] Figure 4 It is a flow chart of a construction method of a prestressed backrest structure of the present invention;

[0044] Icons: 1-back wall, 101-lattice structure, 102-anchor guide pipe, 2-anchor cable, 3-jacking area, 4-jacking platform, 5-jacking pipe section. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with specific embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0046] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are all expressions based on the orientation or position relationship shown in the drawings, or are the orientation or position relationship when the invented product / equipment / device is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.

[0047] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0048] In addition, the expressions “first”, “second”, “third”, etc., which appear in the terms, are merely used to distinguish the description of the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0049] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0050] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0051] Example 1

[0052] like Figures 1 to 3 As shown, a prestressed back-supporting structure of a jacking pipe adopted in this embodiment comprises:

[0053] A rear wall 1 is a reinforced concrete structure and is used to be arranged outside a predetermined starting end of the jacking tunnel. A first side surface of the rear wall 1 faces the predetermined starting end, a plane where the first side surface is located is perpendicular to an axis of the predetermined starting end, a second side surface of the rear wall 1 faces away from the predetermined starting end, and a distance between the first side surface and the second side surface gradually decreases from bottom to top;

[0054] Anchor cable 2 is a prestressed steel bundle, one end of which passes through the rear wall 1 and the other end extends into the slope where the predetermined starting end is located.

[0055] A rear wall 1 is set outside the starting end, and the rear wall 1 can provide recoil force to the jack of the jacking machine, so that the jacking machine receives enough recoil force to move forward. The rear wall 1 is a reinforced concrete structure, and the concrete has excellent compressive performance. It can ensure the rigidity and strength of the rear wall 1 as much as possible, and can withstand the reaction force of the jack as much as possible without being damaged. The first side is perpendicular to the axis of the starting end, so the pressure eccentricity of the rear wall 1 on the jack can be avoided as much as possible, which affects the accuracy of jacking and thus affects the quality of the jacking tunnel. The distance between the second side and the second side gradually decreases from bottom to top, and the second side is an inclined surface, which enhances the strength of the rear wall 1. One end of the anchor cable 2 passes through the rear wall 1, and the other end is anchored to the slope where the predetermined starting end is located. The anchor cable 2 is a prestressed steel bundle, which can increase the force of the rear wall 1 toward the predetermined starting end, and avoid the situation where the device is damaged by the reaction force of the jack as much as possible.

[0056] like Figure 2 and Figure 3As shown, it also includes a stress dispersion member, which is connected to the second side surface of the rear wall 1, and the contact area between the stress dispersion member and the second side surface is greater than the cross-sectional area of ​​the anchor cable 2, and the anchor cable 2 is anchored to the rear wall 1 through the stress dispersion member. The stress dispersion member can be a steel plate or a lattice 101. Because the anchor cable 2 needs to pass through the rear wall 1, and the anchor cable 2 is a prestressed component, a stress dispersion member is provided, and the contact area between the stress dispersion member and the second section is greater than the cross-sectional area of ​​the cable anchor, so that the retraction force of the anchor cable 2 can be evenly transmitted to the rear wall 1 through the stress dispersion member, and the stress concentration at the anchoring point of the cable anchor can be avoided as much as possible, which is conducive to protecting the structural integrity of the rear wall 1. The stress dispersion member is a lattice 101, and the anchor cable 2 passes through the intersection of the lattice 101 and is anchored to the rear wall 1. The anchor cable 2 passes through the intersection of the lattice 101 and is connected to the rear wall 1, which can not only better disperse the stress and reduce the local stress concentration, but also the intersection has a higher local strength, which can better withstand the tension of the anchor cable 2. The stress dissipation element can also be replaced by a steel plate.

[0057] like Figure 1 As shown, the anchor cables 2 include a plurality of anchor guide tubes 102 corresponding to the number of anchor cables 2 are disposed against the rear wall 1, and the plurality of anchor guide tubes 102 are symmetrically arranged along the vertical center line of the second side surface, as shown in FIG. Figure 3 As shown, a plurality of anchoring guide tubes 102 are arranged at intervals along the height direction of the rear wall 1, and the angle between the anchor cable 2 and the horizontal direction gradually increases from top to bottom. Figure 1 The arrow indicates the travel direction of the pipe jacking machine.

[0058] The anchoring guide tube 102 is symmetrically arranged along the vertical center line of the second side surface. When the jack applies pressure to the rear wall 1, uneven force at both ends of the rear wall 1 can be avoided as much as possible, thereby avoiding damage to the rear wall 1 as much as possible and helping to extend the service life of the rear wall 1.

[0059] This structure is also suitable for small TBM (Small Tunnel Boring Machine). Small TBM is a small device used for underground tunnel excavation, suitable for tunnel excavation tasks with smaller diameters. The diameter of a small TBM is usually less than or equal to 3m. Compared with large shield machines, small TBMs have higher flexibility and adaptability, and are suitable for scenes such as urban underground pipe networks, drainage systems, and cable tunnels.

[0060] Example 2

[0061] like Figure 4 As shown, a construction method of a prestressed backrest structure is used to construct a jacking pipe prestressed backrest structure as described in Example 1, comprising the following steps:

[0062] S1, setting the steel bars of the rear wall 1 at a predetermined position, setting a template outside the steel bars of the rear wall 1, and arranging the stress dispersion member on the second side surface of the rear wall 1; drilling an anchor hole for anchoring the cable anchor in the slope at the predetermined starting end by using a soil drill;

[0063] S2, put one end of the anchor cable 2 into the anchor hole, and inject grout into the anchor hole, fix one end of the anchor cable 2 to the side of the stress dispersion component facing away from the second side through the anchor pad, and fix one end of the anchor cable 2 to the side of the stress dispersion component facing away from the second side through the anchor pad; pass the other end of the anchor cable 2 through the steel bar against the wall 1 and cover it with a protective tube, the length of the protective tube matches the distance between the first side and the second side, and fix the anchor cable 2;

[0064] S3, pouring the rear wall 1, and backfilling the jacking area 3 between the rear wall 1 and the predetermined starting end, the top surface of the jacking area 3 is higher than the jacking platform 4;

[0065] S4. After the concrete strength of the back wall 1 reaches 80% of the design value, the anchor cable 2 is tensioned and locked to complete the construction of the jacking pipe prestressed back structure:

[0066] Step S4 is specifically as follows:

[0067] S41, pre-tensioning the anchor cable 2 of each hole according to 0.1Nt-0.2Nt, where Nt is the design value of the axial tension of the anchor cable 2 after tensioning;

[0068] S42, tension the anchor cable 2 in each hole three times at 0.7Nt;

[0069] S43, tension the anchor cable in each hole twice at 0.4Nt;

[0070] S44, loosen the anchor cable 2, and when the tension force of the anchor cable 2 is detected to be Nt, grouting is performed in the gap between the anchor cable 2 and the grouting blind hole, and the grouting slurry strength is measured. When the grouting slurry strength is greater than or equal to 15 MPa, lock the anchor cable 2;

[0071] S5, a guide rail is arranged above the jacking area 3 along the axis of the predetermined starting end, the guide rail is used for the advancement of the pipe jacking machine, a back steel plate is arranged on the first side of the rear wall 1, a jack bracket is arranged on the side of the back steel plate facing the predetermined starting end, and a jack is installed;

[0072] S6. The pipe jacking machine uses a jack to push the pipe forward. During the pipe jacking construction, the pipe is normally pushed into the soil layer at least once for every 1 meter.

[0073] In step S1, anchor holes are drilled, and in step S2, one end of the anchor cable is anchored and grouting is injected into the anchor hole, and the other end passes through the steel bars of the rear wall and is covered with a protective sleeve. When pouring the rear wall, the disturbance to the anchor cable can be reduced as much as possible, so as to avoid adverse effects on the quality of the anchor cable and the rear wall during subsequent tensioning. Tensioning the anchor cable can increase the force toward the predetermined starting end of the rear wall, and avoid the situation where the device is damaged by the reaction force of the jack as much as possible. When pouring the rear wall, the anchor cable is tensioned again, so that the resilience of the anchor cable is transmitted more evenly to the rear wall as much as possible. This construction method can provide the rear wall for the pipe jacking machine while minimizing the interference with the construction of the pipe jacking machine, and avoid the deviation of the actual constructed pipe jacking tunnel compared with the designed pipe jacking tunnel as much as possible.

[0074] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A prestressed backrest structure for a jacking pipe, characterized in that: Include: A rear wall (1) is a reinforced concrete structure, and is used to be arranged outside a predetermined starting end of a jacking tunnel, a first side surface of the rear wall (1) faces the predetermined starting end, a plane where the first side surface is located is perpendicular to the axis of the predetermined starting end, a second side surface of the rear wall (1) faces away from the predetermined starting end, and a distance between the first side surface and the second side surface gradually decreases from bottom to top; The anchor cable (2) is a prestressed steel bundle, one end of the anchor cable (2) penetrates the rear wall (1), and the other end extends into the slope where the predetermined starting end is located.

2. A prestressed backrest structure for jacking pipe according to claim 1, characterized in that: It also includes a stress dispersion component, which is connected to the second side surface of the rear wall (1), the contact area between the stress dispersion component and the second side surface is larger than the cross-sectional area of ​​the anchor cable (2), and the anchor cable (2) is anchored to the rear wall (1) through the stress dispersion component.

3. A prestressed backrest structure for jacking pipe according to claim 2, characterized in that: The stress dispersing member is a lattice structure (101), and the anchor cable (2) passes through the intersection of the lattice structure (101) and is anchored to the rear wall (1).

4. A prestressed backrest structure for a jacking pipe according to any one of claims 1 to 3, characterized in that: The anchor cables (2) include a plurality of anchor guide tubes (102) corresponding to the number of the anchor cables (2) are arranged on the rear wall (1), the plurality of anchor guide tubes (102) are symmetrically arranged along the vertical center line of the second side surface, the plurality of anchor guide tubes (102) are spaced apart along the height direction of the rear wall (1), and the angle between the anchor cables (2) and the horizontal direction gradually increases from top to bottom.

5. A construction method for a prestressed backrest structure, characterized in that: The method for constructing a prestressed pipe backing structure as claimed in any one of claims 1 to 4 comprises the following steps: S1, setting the steel bars of the rear wall (1) at a predetermined position, and setting a template on the outside of the steel bars of the rear wall (1); drilling an anchor hole for anchoring a cable anchor at the side slope where the predetermined starting end is located; S2, placing one end of the anchor cable (2) into the anchor hole and injecting grout into the anchor hole; passing the other end of the anchor cable (2) through the steel bar against the wall (1) and covering it with a protective tube, the length of which matches the distance between the first side surface and the second side surface, and fixing the anchor cable (2); S3, after pouring, against the wall (1); S4. After the concrete strength of the rear wall (1) reaches 80% of the design value, the anchor cable (2) is tensioned and locked to complete the construction of the jacking pipe prestressed rear structure.

6. A construction method for a prestressed backrest structure according to claim 5, characterized in that: Step S3 also includes backfilling a jacking area (3) between the rear wall (1) and the predetermined starting end, wherein the top surface of the jacking area (3) is higher than the jacking platform (4).

7. The construction method of a prestressed backrest structure according to claim 5, characterized in that: Step S1 further comprises arranging a stress dispersing member on a second side surface of the rear wall (1); in step S2, one end of the anchor cable (2) is fixed to a side of the stress dispersing member facing away from the second side surface via an anchor pad.

8. A construction method for a prestressed backrest structure according to any one of claims 5 to 7, characterized in that: Step S4 is specifically as follows: S41, pre-tensioning the anchor cable (2) of each hole according to 0.1Nt to 0.2Nt, wherein Nt is the design value of the axial tension of the anchor cable (2) after tensioning; S42, tensioning the anchor cable (2) in each hole three times at 0.7 Nt; S43, tensioning the anchor cable (2) in each hole twice at 0.4 Nt; S44, loosen the anchor cable (2), and when the tension of the anchor cable (2) is detected to be Nt, grouting is performed in the gap between the anchor cable (2) and the grouting blind hole, and the slurry strength of the grouting is measured. When the slurry strength of the grouting is greater than or equal to 15 MPa, lock the anchor cable (2).

9. A construction method for a prestressed backrest structure according to any one of claims 5 to 7, characterized in that: After step S4, the following steps are further included: S5, a guide rail is arranged above the jacking area (3) along the axis of the predetermined starting end, the guide rail is used for the advancement of the pipe jacking machine, a back steel plate is arranged on the first side of the rear wall (1), a jack bracket is arranged on the side of the back steel plate facing the predetermined starting end, and a jack is installed; S6. The pipe jacking machine pushes the pipe through the jack.

10. A construction method for a prestressed backrest structure according to any one of claims 5 to 7, characterized in that: In step S1, anchor holes are drilled in the slope by using a soil drill.

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