Prestress non-circular shield structure and construction method thereof

Abstract

The invention relates to a prestressed non-circular shield structure and a construction method thereof, and belongs to the technical field of pipe jacking tunnel structures. The shield structure comprises pipe joints, a middle partition wall and a prestress system. The pipe joint comprises a first pipe joint sub-block and a second pipe joint sub-block which are completely consistent in structural form; the prestress system is divided into an annular prestress system and a longitudinal prestress system. In the construction process, the first pipe joint block and the second pipe joint block are assembled into a pipe joint through center rotation and a longitudinal joint face positioning rod, and an annular prestress system is applied; and then the multiple pipe joints are spliced into continuous pipe joints in a staggered joint splicing mode and through circular seam surface rebated tenons, a longitudinal prestress system is applied, and finally a middle partition wall is installed in the middle of the pipe joints to form the shield structure. The mechanical properties such as bearing capacity, rigidity, toughness, recoverability and crack resistance of the shield structure can be effectively improved, structural diseases such as water leakage, sedimentation and large deformation are reduced, the later operation and maintenance cost is reduced, and the use amount of steel bars is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of pipe-jacking tunnel structures, and particularly to a prestressed non-circular shield structure and a construction method thereof. Background Technique

[0002] The pipe-jacking technology is a non-excavation pipe-laying construction technology used for municipal construction. Its advantages are that it has little or no impact on the surrounding environment, requires a small construction site, and produces little noise. Moreover, it can operate deep underground, which is an incomparable advantage of open-cut buried pipes.

[0003] The pipe segment is the lining structure of the pipe-jacking structure. With the increase in the excavation cross-section size, it is restricted by transportation conditions, and some pipe segments begin to adopt a segmented design. The existence of pipe segment joints reduces the overall performance of the pipe segments. After the pipe-jacking structure is subjected to soil and water loads or surrounding construction disturbance loads, it is prone to increase structural deformation, generate structural cracks, joint leakage and other diseases, affecting the durability and long-term operation stability of the pipe-jacking structure.

[0004] CN109519175A discloses a rectangular pipe-jacking and a construction method thereof. The rectangular pipe-jacking includes a plurality of pipe segments that are sequentially aligned, stacked and fixed to each other. Each pipe segment includes an outer frame layer and an inner frame layer that are both in a rectangular frame shape; there is a gap between the outer frame layer and the inner frame layer, and the gap forms a cavity layer. A plurality of reinforcing plates for strengthening the connection strength between the outer frame layer and the inner frame layer are arranged at intervals in the cavity layer; the outer ends of the reinforcing plates are fixedly connected to the inner wall surface of the outer frame layer, and the inner ends of the reinforcing plates are fixedly connected to the outer surface of the inner frame layer; prestressed holes are respectively arranged at the four corners of the cavity; tenons and mortises that cooperate with each other are respectively arranged at both ends of the pipe segment, and adjacent pipe segments are connected by mortise and tenon joints through the cooperation of the tenons and the mortises; a concrete layer is filled in the cavity and the gap between adjacent pipe segments.

[0005] CN103061782A discloses an earth pressure balance rectangular pipe-jacking pipe segment for a large-section motor vehicle tunnel. Taking the direction of pipe-jacking as the forward direction, radial grouting holes penetrating the pipe wall are arranged at intervals along the circumferential direction in the middle of the outer wall surface of the pipe-jacking pipe segment. Hoisting holes are arranged in the middle of the four surfaces of the pipe-jacking pipe segment. Radial thixotropic mud grouting holes penetrating the pipe wall are arranged at intervals along the circumferential direction in the front part of the outer wall surface of the pipe-jacking pipe segment; the top of the pipe-jacking pipe segment is arched, and the four corners of the cross-section of the pipe segment are all arc chamfer structures. The invention also discloses a construction method of the pipe-jacking pipe segment.

[0006] CN116163744A discloses a rectangular pipe jacking curved segment, a manufacturing method, and a curved segment assembly for use in curved pipe jacking projects. The rectangular pipe jacking curved segment has a flat top plate, a bottom plate, and curved side walls. The segment comprises a concrete frame, which serves as the outer frame of the concrete curved segment; internal steel components disposed within the concrete frame, comprising a conventional steel cage disposed within the flat top and bottom plates, and a steel bar disposed within the curved side walls. The steel bar is formed by vertically sequentially joining n sections of identical steel (n≥2) at an angle θ (θ<90°) and welding the joints. The angle θ represents the welding angle.

[0007] Traditional pipe-jacking structures generally have the problem of longitudinal seam misalignment caused by insufficient assembly precision. This type of misalignment not only causes local stress concentration, but also significantly weakens the integrity and waterproof performance of the structure. Especially when subjected to complex water and soil loads, ordinary pipe-jacking structures are prone to mechanical defects such as insufficient axial force and excessive deformation due to the lack of effective prestressed system support, resulting in a significant increase in the amount of steel bars used, making it difficult to balance economy and structural rationality. In addition, existing prestressed pipe-jacking structures have obvious shortcomings in the regulation of longitudinal stiffness. When encountering special working conditions such as ground unloading, the structure's longitudinal settlement control ability is insufficient, which easily leads to the risk of uneven settlement. It is worth noting that the traditional prestressed system has defects in the design of duct sealing. Conventional PVE positioning rods have limited shear resistance and high installation costs. At the same time, the limited installation space of the intermediate partition wall makes it difficult to coordinate the optimization of its functional zoning and bearing capacity. The above technical bottlenecks seriously restrict the application efficiency of pipe-jacking structures in complex engineering environments.

[0008] 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

[0009] To address the shortcomings of existing technologies, the present invention provides a prestressed non-circular shield structure and its construction method. The shield structure utilizes a circumferential prestressing system and positioning rods for circumferential connection, a longitudinal prestressing system and mortise and tenon connections for longitudinal connection, and a central partition wall for segmentation. This invention effectively improves the shield structure's circumferential and longitudinal stiffness and shear strength, reduces longitudinal joint misalignment, reduces the amount of steel required, alleviates structural defects such as water seepage, settlement, and large deformation during tunnel operation, and reduces subsequent operational and maintenance costs. Furthermore, because the shield structure is more rationally stressed, the amount of steel required can be significantly reduced.

[0010] The present invention discloses a prestressed non-circular shield structure, which includes: a pipe segment configured as a reinforced concrete or steel fiber concrete structure in the shape of a rectangular prism, including a first pipe segment block and a second pipe segment block; a middle partition wall configured as a flat plate structure; and a prestressing system including a circumferential prestressing system and a longitudinal prestressing system. The first pipe segment block and the second pipe segment block can be assembled to form a pipe segment by means of central rotation, and the assembled pipe segment can be applied with the circumferential prestressing system; a plurality of pipe segments can be assembled with staggered joints and applied with the longitudinal prestressing system; and the middle partition wall can be installed between the first pipe segment block and the second pipe segment block in each pipe segment.

[0011] According to a preferred embodiment, the first pipe segment block and / or the second pipe segment block are configured with side plates of different lengths on both sides, and positioning rods and first positioning grooves with matching dimensions are respectively arranged on the two longitudinal joint surfaces; longitudinal bosses and longitudinal grooves are respectively arranged at the middle and both sides positions on the two circumferential joint surfaces, and tooth grooves penetrating longitudinally are arranged.

[0012] According to a preferred embodiment, a plurality of circumferential prestressing ducts are arranged along the circumferential width direction of the first pipe segment block and / or the second pipe segment block, annular grooves are arranged at the ends of the circumferential prestressing ducts, and the circumferential prestressing ducts include a circumferential segment located at the center of the pipe segment cross-section, a lifting segment close to the longitudinal joint surface, and independent segments respectively connected to the longitudinal joint surface and the arc-shaped tensioning groove at both ends.

[0013] According to a preferred embodiment, after the pipe segment assembly is completed, the circumferential segment of the first pipe segment block is connected to the circumferential segment of the second pipe segment block, the independent segment of the first pipe segment block is connected to the lifting segment of the second pipe segment block, and the lifting segment of the first pipe segment block is connected to the independent segment of the second pipe segment block, finally forming a circumferential prestressing duct that penetrates along the circumferential direction of the pipe segment.

[0014] According to a preferred embodiment, the circumferential prestressing duct is a through duct that surrounds the pipe segment for one circle, and is lifted from the central cross-section of the pipe segment and led out from the inner arc surface in a cross manner near the tensioning position, and an arc-shaped tensioning groove is arranged on the part led out from the inner arc surface.

[0015] According to a preferred embodiment, two longitudinal prestressing ducts penetrating the longitudinal boss and the longitudinal groove are arranged at the middle position of the first pipe segment block and / or the second pipe segment block, and first longitudinal tensioning grooves and second longitudinal tensioning grooves are arranged at both ends of the two longitudinal prestressing ducts.

[0016] According to a preferred embodiment, the circumferential prestressed system and the longitudinal prestressed system can respectively adopt a bonded tensioning scheme and a non-bonded tensioning scheme, wherein when the circumferential prestressed system adopts a bonded tensioning scheme, an exhaust hole is set at the top position of the circumferential prestressed channel on the first pipe segment block and / or the second pipe segment block; when the longitudinal prestressed system adopts a bonded tensioning scheme, a grouting hole is set on the first pipe segment block and / or the second pipe segment block, which passes through the inner arc surface to the longitudinal prestressed channel.

[0017] According to a preferred embodiment, a reinforcement plate and a plurality of positioning pins are provided at the bottom of the tooth groove of the first pipe section block and / or the second pipe section block, the thickness of the middle partition wall is smaller than the width of the tooth groove, and a plurality of second positioning grooves matching the positioning pins are provided at the bottom of the middle partition wall.

[0018] The present invention also discloses a construction method of a prestressed non-circular shield structure, which comprises the following steps:

[0019] Assembling the first pipe segment block and the second pipe segment block into a pipe segment;

[0020] A pipe segment is selected as the first pipe segment, and the circumferential prestressed strand is passed through it in sequence and tensioned and anchored at both ends. Then, the first longitudinal prestressed strand is passed through the first longitudinal tensioning groove of the first pipe segment and anchored at one end.

[0021] Before assembling the second pipe segment, insert the first longitudinal prestressed strand of the first pipe segment into the second longitudinal tensioning groove of the second pipe segment, and insert the second longitudinal prestressed strand through the first longitudinal tensioning groove of the second pipe segment and anchor one end;

[0022] Assemble the second pipe segment and tension and anchor the two ends of the circumferential prestressed strand, and then tension and anchor the unanchored end of the first longitudinal prestressed strand;

[0023] Before assembling the third pipe segment, insert the second longitudinal prestressed strand into the second longitudinal tensioning groove of the third pipe segment, and insert the first longitudinal prestressed strand into the first longitudinal tensioning groove of the third pipe segment and anchor one end;

[0024] The third pipe segment is assembled and both ends of the annular prestressed strand are tensioned and anchored, and then the second longitudinal prestressed strand is tensioned and anchored.

[0025] According to a preferred embodiment, the construction method further comprises the following steps:

[0026] After the tunnel is completed, the middle partition wall is installed and the gap between the middle partition wall and the tooth groove is filled.

[0027] The present invention has the following beneficial technical effects:

[0028] 1. The present invention can provide additional axial force and radial force for the shield structure by applying circumferential prestress, making it a self-stabilizing structural system. Furthermore, mechanical properties such as structural bearing capacity, stiffness, toughness, recoverability, and crack resistance can be greatly improved, reducing joint cracking and water leakage at the longitudinal joint surface.

[0029] 2. The present invention applies longitudinal prestress to the shield structure in a sequential lap joint manner, ensuring that all segments are in a state of longitudinal prestress after assembly, guaranteeing longitudinal structural safety. At the same time, the longitudinal prestress and the concave-convex tenon jointly serve as connectors for the circumferential joint surface, effectively improving the longitudinal stiffness and deformation resistance of the shield structure, reducing longitudinal settlement and water leakage at the circumferential joint surface.

[0030] 3. The present invention can change the force pattern of the shield structure, increase the axial force of the shield structure and reduce deformation, making the structural force more reasonable. On the premise of meeting the design requirements, the amount of steel bars used can be significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the front view of the prestressed non-circular shield structure provided by the present invention;

[0032] Figure 2 is the side view of the prestressed non-circular shield structure provided by the present invention;

[0033] Figure 3 is the structural schematic diagram of the first segment block provided by the present invention;

[0034] Figure 4 is Figure 3 the schematic diagram of the A-A cross-section of

[0035] Figure 5 is Figure 3 the schematic diagram of the B-B cross-section of

[0036] Figure 6 is Figure 3 the schematic diagram of the C-C cross-section of

[0037] Figure 7 is the structural schematic diagram of the middle partition wall provided by the present invention;

[0038] Figure 8A 、 8B 、8C, 8D are the flowcharts of the construction method of the present invention;

[0039] Figure 9 is the axial force distribution diagram of the prestressed non-circular shield structure and the ordinary jacking pipe structure under soil and water loads;

[0040] Figure 10 is the bending moment distribution diagram of the prestressed non-circular shield structure and the ordinary jacking pipe structure under soil and water loads;

[0041] Figure 11 It is the horizontal deformation distribution diagram of the prestressed non-circular shield structure and the ordinary pipe jacking structure under the soil and water load;

[0042] Figure 12 It is the vertical deformation distribution diagram of the prestressed non-circular shield structure and the ordinary pipe jacking structure under the soil and water load;

[0043] Figure 13 It is the longitudinal top settlement comparison diagram of the prestressed non-circular shield structure and the ordinary pipe jacking structure under the unloading condition;

[0044] Figure 14 It is the longitudinal bottom settlement comparison diagram of the prestressed non-circular shield structure and the ordinary pipe jacking structure under the unloading condition.

[0045] List of reference numerals

[0046] 100: Pipe segment; 101: First pipe segment block; 102: Second pipe segment block; 103: Middle partition wall; 104: Circumferential prestressing system; 105: Longitudinal prestressing system; 201: Positioning rod; 202: First positioning groove; 203: Longitudinal boss; 204: Longitudinal groove; 205: Tooth groove; 301: Circumferential prestressing duct; 302: Circumferential section; 303: Lifting section; 304: Independent section; 305: Arc-shaped tensioning groove; 306: Annular groove; 400: Longitudinal prestressing duct; 401: First longitudinal tensioning groove; 402: Second longitudinal tensioning groove; 403: Grouting hole; 404: Vent hole; 501: Reinforcement plate; 502: Positioning pin; 503: Second positioning groove; 600: Circumferential prestressing strand; 601: First longitudinal prestressing strand; 602: Second longitudinal prestressing strand; 1000: Second pipe segment; 10000: Third pipe segment. Detailed implementation manners

[0047] The following is a detailed description with reference to the accompanying drawings.

[0048] Figure 1 and Figure 2 show the front view and side view of the prestressed non-circular shield structure.

[0049] The present invention discloses a prestressed non-circular shield structure, which includes a pipe segment 100, a middle partition wall 103 and a prestressing system.

[0050] Preferably, the pipe segment 100 is an independent ring unit of the shield structure, which is configured as a quasi-rectangular structure and can be prefabricated in a factory using reinforced concrete or steel fiber concrete. Further, the cross-section of the pipe segment 100 of the quasi-rectangular structure is composed of several smooth and derivable curves, forming a closed contour similar to a rectangle. The four corners of the quasi-rectangular structure are rounded corners with the same or similar radius of curvature, and the straight segments at the top and around can also be set as arcs with a radius of curvature greater than that of the rounded corners according to needs. The combination of the rounded corners and arcs of the quasi-rectangular structure can reduce the stress concentration at the corners after the circumferential prestressed strands 600 are tensioned, facilitating stress transfer and ensuring structural safety. The pipe segment 100 may include a first pipe segment block 101 and a second pipe segment block 102. Preferably, the first pipe segment block 101 and the second pipe segment block 102 can adopt exactly the same structural form. Therefore, the following will mainly describe the first pipe segment block 101 in detail.

[0051] Preferably, the middle partition wall 103 is a flat plate structure with the same width as the ring width of the pipe segment 100. For the strata with good geotechnical conditions around the shield structure, the middle partition wall 103 is mainly used for separating the two sides and functional zoning, reducing the vibration and noise during train operation, and can be made of energy-absorbing materials such as thin corrugated plates and shock-absorbing plates without being used as a load-bearing structure to improve the driving comfort. For the strata with poor geotechnical conditions around the shield structure, in addition to meeting the above functions, the middle partition wall 103 also serves as a load-bearing structure and needs to share the stratum pressure at the top and sides of the tunnel, and its thickness and reinforcement need to meet the design requirements.

[0052] Preferably, the prestress system can provide additional internal forces for the shield structure, which includes a circumferential prestress system 104 and a longitudinal prestress system 105. Among them, the circumferential prestress system 104 can provide an axial force along the tangential direction of the pipe segment 10 and a radial force pointing to the center of the circle, and the longitudinal prestress system 105 can provide an axial force along the ring width direction of the pipe segment 100 and vertical shear bearing capacity.

[0053] Preferably, during the construction of the shield structure, first fix the second pipe segment block 102 at the bottom, then hoist the first pipe segment block 101 and fix it with the second pipe segment block 102 by rotating 180° around the center to complete the assembly of the pipe segment 100; then apply the circumferential prestress system 104 to the pipe segment 100, and at this time the pipe segment 100 can bear the water and soil loads; then adopt the staggered joint assembly scheme to assemble the subsequent pipe segments 100, and apply the longitudinal prestress system 105 in turn by overlapping; finally, after the shield structure is completely penetrated, the middle partition wall 103 can be installed at one time in the middle position of the pipe segment 100 to form the shield structure.

[0054] Preferably, the specific operation of lapping and applying the longitudinal prestressing system 105 may include: first, tensioning and anchoring the pipe segment 100 and the second pipe segment 1000, and then tensioning and anchoring the second pipe segment 1000 and the third pipe segment 10000, and sequentially circulating to complete the application of the longitudinal prestress of the entire shield structure.

[0055] Figures 3 - 6 The structural schematic diagram of the first pipe segment block 101 is shown.

[0056] Preferably, to achieve the staggered assembly of the pipe segment 100 and improve the overall structural stiffness and waterproof performance, the side plates on both sides of the first pipe segment block 101 are configured with different lengths. After the first pipe segment block 101 and the second pipe segment block 102 are assembled into the pipe segment 100, the longitudinal joint surfaces of the same pipe segment 100 and adjacent pipe segments 100 are not in the same plane.

[0057] Preferably, to ensure the assembly accuracy of the pipe segment 100, a protruding (concrete) positioning rod 201 is provided on one side of the longitudinal joint surfaces on both sides of the first pipe segment block 101, and a first positioning groove 202 matching the size of the positioning rod 201 is provided on the other side. Compared with the traditional PVE positioning rod, the (concrete) positioning rod 201 can be directly precast on the structural longitudinal joint surface, with lower cost, better shear resistance, and no need for installation.

[0058] Preferably, to improve the shear bearing capacity of the circumferential joints of the pipe segment 100 and increase the longitudinal stiffness, concave and convex tenons are respectively provided on the circumferential joint surfaces on both sides of the pipe segment 100, which include a longitudinal boss 203 and a longitudinal groove 204, and the size or quantity of the concave and convex tenons can be adjusted according to the buried depth of the shield structure. Generally, only one concave and convex tenon with a larger size can be provided at the middle position of the circumferential joint surface, and multiple concave and convex tenons can be provided at the middle and both sides of the circumferential joint surface when the formation conditions are poor. The calculation formula for the size of the concave and convex tenon is as follows:

[0059] ∑0.7f t b i h j >∑γ i h i ,

[0060] In the formula, f t is the design value of the tensile strength of concrete or steel fiber concrete; b i is the width of the i-th concave and convex tenon; h j is the height of the j-th concave and convex tenon; γ i is the unit weight of the i-th layer of overburden above the shield structure; h i is the thickness of the i-th layer of overburden above the shield structure.

[0061] Preferably, to position and fix the middle partition wall 103, longitudinal through grooves 205 are designed on the inner surfaces in the middle of the first pipe segment block 101 and the second pipe segment block 102.

[0062] Figures 4 - 6 Shows a schematic cross-section of the circumferential prestressed duct 301 of the first pipe segment block 101. As Figures 2 - 6 shown, the first pipe segment block 101 is provided with multiple circumferential prestressed ducts 301 along the circumferential width direction. The spacing between the circumferential prestressed ducts 301 and their distances from the structural boundaries should meet the design requirements of prestressed concrete structures. Annular grooves 306 are provided at the ends of the circumferential prestressed ducts 301 located on the longitudinal joint surface. An annular water-swellable gasket is placed in the annular groove 306, which can seal the circumferential prestressed duct 301 and ensure that the durability of the prestressed strands after tensioning meets the service life requirements. The annular groove 306 is located at the end of the longitudinal joint surface of the circumferential prestressed duct 301, that is, an annular groove 306 is provided at the end of the circumferential prestressed duct 301. It is recommended that the outer diameter of the annular groove 306 be 15 mm larger than the outer diameter of the prestressed duct 301, and the depth is recommended to be about 5 mm. An annular water-swellable gasket (the swelling rate after contacting water can be close to 400%) is placed in the annular groove 306. It is recommended that the inner diameter of the annular gasket be 5 mm larger than the outer diameter of the circumferential prestressed duct 301, the outer diameter is recommended to be slightly smaller than the outer diameter of the annular groove 306, such as 1 mm smaller, and the thickness should be greater than 5 mm, preferably 6 - 7 mm.

[0063] Preferably, for the pipe segment 100, the circumferential prestressed duct 301 is a through-hole that surrounds the pipe segment 100 for one circle, and is lifted from the central section of the pipe segment 100 and led out from the inner arc surface in a cross-over manner near the tensioning position. An arc-shaped tensioning groove 305 is provided in the part led out from the inner arc surface to provide the tensioning and anchoring space for the circumferential prestressed strands 600. Since the tensioning position of the circumferential prestressed duct 301 is set near the longitudinal joint surface, there will be two ducts at the same section of each circumferential prestressed duct 301 on the first pipe segment block 101 near the arc-shaped tensioning groove 305, such as Figure 4 the right side of Figure 5On the left side. The two independent duct segments include the first duct composed of the circumferential segment 302 located at the center of the cross-section of the pipe segment 100 and the lifting segment 303 close to the longitudinal joint surface, and the second duct formed by the independent segment 304 whose two ends are respectively connected to the longitudinal joint surface and the arc-shaped tensioning groove 305. The independent segment 304 is a straight duct, perpendicular to the tensioning surface of the arc-shaped tensioning groove 305, and the length of the independent segment 304 is recommended to be greater than 1 m; there is a large included angle between the circumferential segment 302 and the independent segment 304, and a large-curvature duct segment, that is, the lifting segment 303, is required to connect them. The radius of curvature of the lifting segment 303 is related to many factors such as the curvature of the pipe segment 100 in this area, the length of the independent segment 304, and the duct diameter, and targeted design is required. Generally speaking, the radius of curvature of the lifting segment 303 should be greater than 1 m. The lifting height of the lifting segment 303 can be obtained after determining the length of the independent segment 304 and the radius of curvature of the lifting segment 303. The purpose of setting the radius of curvature of the lifting segment 303 (greater than 1 m) is to prevent stress concentration in this area after the circumferential prestressed strands 600 are tensioned. Considering that the length of the independent segment 304 needs to be greater than 1 m, the position of the lifting segment 303 close to the joint surface may also include a section (straight section) of the independent segment 304.

[0064] Preferably, since the structural forms of the first pipe segment block 101 and the second pipe segment block 102 are exactly the same, after being assembled into the pipe segment 100 by central rotation of 180°, the circumferential segment 302 of the first pipe segment block 101 is connected to the circumferential segment 302 of the second pipe segment block 102, the independent segment 304 of the first pipe segment block 101 is connected to the lifting segment 303 of the second pipe segment block 102, and the lifting segment 303 of the first pipe segment block 101 is connected to the independent segment 304 of the second pipe segment block 102, finally forming the circumferential prestressed duct 301 that runs through the pipe segment 100 in the circumferential direction.

[0065] Preferably, considering that the misalignment during the jacking pipe assembly will cause a docking tolerance between the independent segment 304 and the lifting segment 303, the cross-sectional area of the circumferential prestressed duct 301 should be greater than 3 times the cross-sectional area of the circumferential prestressed strands 600. The large area difference between the two gives sufficient misalignment space, and the misalignment caused by the assembly will not affect the cable-pulling efficiency of the circumferential prestressed strands 600. In addition, the circumferential prestress can greatly increase the pressure on the longitudinal joint surface of the shield structure, and the design of the positioning rod 201 can reduce the assembly error, and the misalignment amount of the longitudinal joint surface is smaller.

[0066] Preferably, the longitudinal prestressed ducts 400 of the first pipe segment block 101 are arranged at the concave-convex tenons in the middle of the circumferential joint surface and are 2 ducts running through longitudinally. To meet the tensioning of the longitudinal prestress, the first longitudinal tensioning grooves 401 and the second longitudinal tensioning grooves 402 need to be provided at the longitudinal convex platforms 203 and longitudinal grooves 204 at the concave-convex tenons. The structural dimensions of the first longitudinal tensioning groove 401 and the second longitudinal tensioning groove 402 are the same and are circular or square grooves.

[0067] Preferably, both the circumferential prestressing system 104 and the longitudinal prestressing system 105 can adopt the bonded tensioning scheme and the unbonded tensioning scheme. When the circumferential prestressing system 104 adopts the bonded tensioning scheme, an exhaust hole 404 needs to be arranged at the top position of the circumferential prestressing duct 301 of the first pipe segment block 101. Grouting is carried out by the arc-shaped tensioning groove 305. The gas in the circumferential prestressing duct 301 is first discharged from the exhaust hole 404 at the top, and finally the slurry is discharged from the exhaust hole 404, indicating that the grouting is completed. When the longitudinal prestressing system 105 adopts the bonded tensioning scheme, grouting holes 403 penetrating from the inner arc surface to the longitudinal prestressing duct 400 need to be arranged on the first pipe segment block 101. The grouting holes 403 should be located at both ends of the longitudinal prestressing duct 400, and the grouting holes 403 can also serve as exhaust holes.

[0068] Preferably, a plurality of pipe segments 100 are used as a longitudinal prestressing section longitudinally in the prestressed non-circular shield structure. Among them, during the grouting process, grouting is carried out from the first grouting hole 403 of the longitudinal prestressing section, and the last grouting hole 403 is used for exhausting, and the multiple intermediate grouting holes 403 are blocked.

[0069] Figure 7 The structural schematic diagram of the middle partition wall 103 is shown. A plurality of second positioning grooves 503 are arranged on both the upper and lower surfaces of the middle partition wall 103. The middle partition wall 103 is installed in the tooth groove 205 of the first pipe segment block 101. A reinforcing plate 501 and a plurality of positioning pins 502 are arranged at the bottom of the tooth groove 205 of the first pipe segment block 101. The reinforcing plate 501 can disperse the load of the middle partition wall 103 on the bottom of the tooth groove 205 and avoid damaging the longitudinal prestressing duct 400. The functions of the second positioning groove 503 and the positioning pin 502 are to position and fix the middle partition wall 103.

[0070] Preferably, the height of the middle partition wall 103 is lower than the net distance between the upper and lower tooth grooves 205 of the pipe segment 100, the thickness of the middle partition wall 103 is less than the width of the tooth groove 205, and at the same time, the convex height on one side of the tooth groove 205 is relatively low to ensure that the middle partition wall 103 has sufficient installation space.

[0071] The present invention also discloses a construction method of a prestressed non-circular shield structure, and through this construction method, the above-mentioned prestressed non-circular shield structure can be obtained. Preferably, the construction method may include the following steps:

[0072] S1. Batch prefabricate the first pipe segment block 101 and the second pipe segment block 102 in the factory, including steel reinforcement cage processing, installation of the circumferential prestressing duct 301, installation of the longitudinal prestressing duct 400, concrete pouring, curing, etc. Before the pipe segments 100 are assembled, an annular gasket is installed in the annular groove 306;

[0073] S2. Fix the second pipe segment block 102 at the bottom. After hoisting the first pipe segment block 101 and rotating it 180° around the center, position and fix it to the second pipe segment block 102 through the positioning rod 201 and the first positioning groove 202 to complete the assembly of the pipe segment 100.

[0074] S3. As Figure 8A , successively thread the circumferential prestressing ducts 301 with the circumferential prestressing strands 600. Perform tensioning and anchoring at both ends using a two-way synchronous graded tensioning scheme to complete the application of circumferential prestress to the pipe segment 100. Then, thread the first longitudinal prestressing strand 601 through the first longitudinal tensioning groove 401 of the pipe segment 100 and anchor it at one end. Among them, the length of the first longitudinal prestressing strand 601 needs to be greater than the sum of twice the circumferential width of the pipe segment 100 and the reserved length for anchoring.

[0075] S4. As Figure 8B , before assembling the second pipe segment 1000, thread the first longitudinal prestressing strand 601 of the pipe segment 100 through the second longitudinal tensioning groove 402 of the second pipe segment 1000, and thread the second longitudinal prestressing strand 602 through the first longitudinal tensioning groove 401 of the second pipe segment 1000 and anchor it at one end. Among them, the second longitudinal prestressing strand 602 has the same length as the first longitudinal prestressing strand 601.

[0076] S5. As Figure 8C , the second pipe segment 1000 is positioned and fixed to the pipe segment 100 through the longitudinal boss 203 and the longitudinal groove 204 to complete the assembly of the second pipe segment 1000. Then, perform tensioning and anchoring at both ends of the circumferential prestressing strands 600 of the second pipe segment 1000. Then, perform tensioning and anchoring of the first longitudinal prestressing strand 601 on the circumferential joint surface where the second pipe segment 1000 does not contact the pipe segment 100 to complete the application of longitudinal prestress between the pipe segment 100 and the second pipe segment 1000.

[0077] S6. As Figure 8D , before assembling the third pipe segment 10000, thread the second longitudinal prestressing strand 602 through the second longitudinal tensioning groove 402 of the third pipe segment 10000, and thread the first longitudinal prestressing strand 601 through the first longitudinal tensioning groove 401 of the third pipe segment 10000 and anchor it at one end.

[0078] S7. Assemble the third pipe segment 10000 and perform tensioning and anchoring at both ends of the circumferential prestressing strands 600. Then, perform tensioning and anchoring at the unanchored end of the second longitudinal prestressing strand 602 to complete the application of longitudinal prestress between the second pipe segment 1000 and the third pipe segment 10000.

[0079] S8. Repeat steps S6 and S7 to complete the construction of subsequent pipe segments 100.

[0080] After the tunnel is through, install the middle partition wall 103 and fill the gap between the middle partition wall 103 and the tooth groove 205.

[0081] Preferably, if the bonded tensioning scheme is adopted, after the tunnel is through, grout the circumferential prestressed duct 301 and the longitudinal prestressed duct 400 in sequence, and install the middle partition wall 103 and fill the gap between the middle partition wall 103 and the tooth groove 205. If the unbonded tensioning scheme is adopted, directly install the middle partition wall 103 and fill the gap between the middle partition wall 103 and the tooth groove 205 after the tunnel is through.

[0082] The following shows the comparison of the mechanical properties between the prestressed non-circular shield structure of the present invention and the ordinary pipe jacking structure under the water and soil load conditions. The "prestressed non-circular shield structure" mentioned below all refers to the prestressed non-circular shield structure of the present invention.

[0083] Use midas software to establish three-dimensional solid models of the ordinary pipe jacking structure and the prestressed non-circular shield structure. The width of the pipe sections of the ordinary pipe jacking structure and the prestressed non-circular shield structure is 13m, the height is 8.7m, the thickness is 0.7m, and the width of the section is 1.5m. The model has a total of 10 pipe sections. The longitudinal joint surface of the ordinary pipe jacking structure is connected by 2 M30 bolts, and the longitudinal joint surface is connected by 8 M30 bolts; each circumferential prestressed duct of the prestressed non-circular shield structure uses 6 prestressed steel strands of 15.2mm, with an area of 840mm 2 , and each longitudinal prestressed duct uses 8 prestressed steel strands of 15.2mm, with an area of 1120mm 2 , and the tension control stress is 1320MPa for both. Positioning rods 201 and male and female tenons are respectively set on the longitudinal joint surface and the circumferential joint surface.

[0084] Both the ordinary pipe jacking structure and the prestressed non-circular shield structure adopt C50 concrete, with an elastic modulus of 3.45×10 7 kN / m 2 , a Poisson's ratio of 0.2, and a unit weight of 25kN / m 3 . The normal stiffness coefficient of the circumferential joint surface and the longitudinal joint surface is 1×10 6 , the tangential stiffness coefficient is 1×10 5 , the contact error is 0mm, and the friction coefficient is 0.3. The prestressed steel strands adopt the bonded tensioning scheme, the friction coefficient of the prestressed duct wall is 0.2, the influence coefficient of the local deviation per meter of the prestressed duct on friction is 0.0015, the deformation of the tensioning end anchor and the shrinkage value of the prestressed steel bar are 6mm, and the elastic modulus of the prestressed steel strand is 195GPa.

[0085] The buried depth of the pipe jacking structure is 10 m. Uniform loads of 0.2 MPa are applied to the upper and lower parts of the ordinary pipe jacking structure and the prestressed non-circular shield structure, and uniform loads of 0.12 MPa are applied to the left and right sides. The interaction between the pipe jacking structure and the stratum is simulated by foundation springs, with a normal stiffness of 900 kN / m and a tangential stiffness of 300 kN / m for the foundation springs.

[0086] The loading process of the ordinary pipe jacking structure under soil and water loads is as follows: ① Establish a three-dimensional solid model of a multi-ring ordinary pipe jacking structure; ② Apply the surrounding loads simultaneously.

[0087] The loading process of the prestressed non-circular shield structure under soil and water loads is as follows: ① Establish a three-dimensional solid model of a multi-ring prestressed non-circular shield structure; ② Establish circumferential prestressed strands and apply tensile control stress; ③ Establish longitudinal prestressed strands and apply tensile control stress; ④ Apply the surrounding loads simultaneously.

[0088] Figure 9 and Figure 10 respectively show the axial force and moment distributions of the prestressed non-circular shield structure and the ordinary pipe jacking structure under soil and water loads. The axial force of the ordinary pipe jacking structure under soil and water loads is between 1778.9 kN and 1227.8 kN, and the axial force of the prestressed non-circular shield structure is between 2203.1 kN and 2998.9 kN; the moment of the ordinary pipe jacking structure under soil and water loads is between -1194.1 kN·m and 664.5 kN·m, and the moment of the prestressed non-circular shield structure is between -1215.3 kN·m and 736.8 kN·m. Compared with the ordinary pipe jacking structure, the axial force of the prestressed non-circular shield structure increases by 70.6%, and the moment increases by 7.4%.

[0089] Figure 11 and Figure 12 show the deformation distributions in the horizontal and vertical directions of the prestressed non-circular shield structure and the ordinary pipe jacking structure under soil and water loads. The maximum deformations in the horizontal direction of the ordinary pipe jacking structure and the prestressed non-circular shield structure under soil and water loads are 14.2 mm and 10.2 mm respectively, and the deformations in the vertical direction are 19.7 mm and 18.3 mm respectively. Compared with the ordinary pipe jacking structure, the deformation in the horizontal direction of the prestressed non-circular shield structure decreases by 28.2%, and the deformation in the vertical direction decreases by 7.1%. In addition, there is an obvious offset at the longitudinal joint surface of the ordinary pipe jacking structure.

[0090] Based on the axial force and moment distributions of the prestressed non-circular shield structure and the ordinary pipe jacking structure under soil and water loads, the reinforcement calculation is carried out using the current national standard "Code for Design of Concrete Structures" GB / T 50010. The reinforcement areas of the main bars on the inner and outer sides of the prestressed non-circular shield structure are 9651 mm 2 and 2290 mm 2。The cross-sectional areas of the main longitudinal reinforcement bars on the inner and outer sides of the ordinary pipe jacking structure are 11259 mm 2 and 4084 mm 2 respectively. Compared with the ordinary pipe jacking structure, the cross-sectional area of the main longitudinal reinforcement bars of the prestressed non-circular shield structure is reduced by 22.2%.

[0091] That is, the axial force of the prestressed non-circular shield structure is greater, the deformation is smaller, and the steel consumption is lower, with a more reasonable stress form than the ordinary pipe jacking structure. At the same time, the design of the longitudinal joint surface positioning rod 201 and the higher pressure provided by the circumferential prestress for the longitudinal joint surface can effectively reduce the dislocation amount of the longitudinal joint surface, which is beneficial to improving the waterproof performance of the structure.

[0092] The following shows the comparison of the mechanical properties between the prestressed non-circular shield structure of the present invention and the ordinary pipe jacking structure under the unloading condition. The "prestressed non-circular shield structure" mentioned below all refers to the prestressed non-circular shield structure of the present invention.

[0093] Under the unloading condition, the design parameters, surrounding water and soil loads of the prestressed non-circular shield structure and the ordinary pipe jacking structure are the same as those in the previous text.

[0094] The loading process of the ordinary pipe jacking structure under the unloading condition is as follows: ① Establish a three-dimensional solid model of a multi-ring ordinary pipe jacking structure; ② Apply the surrounding loads simultaneously; ③ Reduce the foundation spring stiffness within the range of 90° at the bottom of the middle four-ring pipe jacking structure to 0 and reduce the load to 0.1 MPa.

[0095] The loading process of the prestressed non-circular shield structure under the unloading condition is as follows: ① Establish a three-dimensional solid model of a multi-ring prestressed non-circular shield structure; ② Establish circumferential prestressed strands and apply the tensile control stress; ③ Establish longitudinal prestressed strands and apply the tensile control stress; ④ Apply the surrounding loads simultaneously; ⑤ Reduce the foundation spring stiffness within the range of 90° at the bottom of the middle four-ring pipe jacking structure to zero and reduce the load to 0.1 MPa.

[0096] Figure 13 and Figure 14 show the longitudinal top and bottom settlements of the prestressed non-circular shield structure and the ordinary pipe jacking structure under the unloading condition. Under the unloading condition, the maximum settlements of the prestressed non-circular shield structure and the ordinary pipe jacking structure are both at the middle position in the longitudinal direction. The maximum top settlements are 0.26 mm and 1.68 mm respectively, and the maximum bottom settlements are 2.90 mm and 6.65 mm respectively. Compared with the ordinary pipe jacking structure, the maximum top settlement of the prestressed non-circular shield structure is reduced by 84.5%, and the maximum bottom settlement is reduced by 56.4%.

[0097] That is, the prestressed non-circular shield structure has higher longitudinal stiffness and can significantly reduce the longitudinal settlement of the pipe jacking structure.

[0098] By comparing the mechanical properties of the prestressed non-circular shield structure of the present invention and the ordinary jacking pipe structure under water and soil load conditions and unloading conditions, it can be seen that:

[0099] 1. The hoop prestressing system 104 and the longitudinal prestressing system 105 of the present invention offset the active effects of external loads by applying precompression, directly leading to a significant increase in axial force and bending moment. The hoop prestressing strands (six 15.2 mm strands per ring) create a continuous compressive stress field in the hoop, while the longitudinal prestressing strands (eight 15.2 mm strands per ring) establish a precompression state in the longitudinal direction by tensioning and controlling the stress (1320 MPa). This precompression allows the structure to share external loads through internal prestressing when subjected to water and soil loads, thereby increasing the axial force to 2203.1 kN to 2998.9 kN (a 70.6% increase compared to conventional pipe jacking structures). Furthermore, the uniform distribution of prestress reduces local stress concentrations, expanding the bending moment range from -1194.1 kN·m to 664.5 kN·m to -1215.3 kN·m to 736.8 kN (a 7.4% increase). Further analysis shows that the longitudinal prestressing system 105 significantly improves the longitudinal stiffness of the structure under unloaded conditions through the synergistic effect of the anchorage ends and the foundation springs (tangential stiffness 300 kN / m). This reduces top settlement from 1.68 mm to 0.26 mm (an 84.5% decrease) and bottom settlement from 6.65 mm to 2.90 mm (a 56.4% decrease). This increased stiffness is attributed to the longitudinal prestressing strands' ability to constrain structural deformation. The design of the anchorage deformation and shrinkage (6 mm) at the tensioning end optimizes prestress transfer efficiency and ensures the continued effect of prestress throughout the structure's lifecycle.

[0100] 2. The center rotation assembly method adopted by the prestressed non-circular shield structure of the present invention and the design of the longitudinal seam surface positioning rod 201, the first positioning groove 202, the longitudinal boss 203, and the longitudinal groove 204 are controlled by geometric constraints and contact surface stiffness (normal stiffness 1×10 6 , tangential stiffness 1×10 5), significantly reducing the uneven settlement at the joints. Due to the insufficient stiffness of the bolt connection method (2 M30 bolts on the longitudinal joint surface and 8 M30 bolts on the circumferential joint surface) in the ordinary pipe-jacking structure, obvious longitudinal joint uneven settlement is likely to occur under load. While in the prestressed non-circular shield structure, through the fitting design of the positioning rod 201 and the groove, the contact pressure on the longitudinal joint surface is homogenized, reducing the maximum horizontal deformation from 14.2 mm to 10.2 mm (a decrease of 28.2%). In addition, the design of the convex platform and groove on the circumferential joint surface further reduces the deformation difference in the vertical direction (from 19.7 mm to 18.3 mm) by increasing the anti-slip ability of the contact surface (friction coefficient 0.3). This improvement in geometric accuracy not only enhances the integrity of the structure but also effectively prevents the formation of water seepage paths by reducing the small displacements at the joints, thus improving the waterproof performance.

[0101] 3. The design of the lifting section 303 and the independent section 304 of the present invention improves the uniformity of the prestress distribution by optimizing the layout path of the prestressed strands. Specifically, in the lifting section 303, by adjusting the relative position of the strands and the concrete, the pre-compressive stress is more concentrated in the tensile area, while in the independent section 304, stress concentration is avoided by reducing the local deviation of the ducts (influence coefficient 0.0015 / m). This optimization directly reduces the tensile demand of the concrete, reducing the main reinforcement area from the inner side of 11259 mm² and the outer side of 4084 mm² in the ordinary pipe-jacking structure to the inner side of 9651 mm² and the outer side of 2290 mm² in the prestressed structure (a decrease of 22.2%). At the same time, the design of the annular groove 306 enhances the bond force between the prestressed strands and the concrete (elastic modulus 195 GPa), improving the prestress transfer efficiency and increasing the axial force from 1778.9 kN in the ordinary structure to 2203.1 kN. This result shows that the geometric optimization of the prestressed ducts and the matching of material properties are the key factors for achieving structural lightweight and economy.

[0102] 4. The middle partition wall 103 with a flat plate structure of the present invention forms a synergistic effect with the prestress system by providing lateral restraint. The rigid structure of the middle partition wall 103 (C50 concrete, elastic modulus 3.45×10 7 kN / m²) disperses the local acting force of the soil and water load laterally, reducing the deformation difference in the vertical direction (from 19.7 mm to 18.3 mm). The realization of this effect depends on the combined action of the middle partition wall 103 and the prestressed strands: the circumferential prestressed strands 600 limit the lateral displacement of the middle partition wall 103 through the compressive stress field, while the middle partition wall 103 enhances the stability of the prestress system in the reverse direction through rigid support. This two-way restraint mechanism is particularly significant under the unloading condition. For example, when the stiffness of the bottom foundation spring drops to 0, the lateral stiffness of the middle partition wall 103 can still maintain the integrity of the structure, thus controlling the longitudinal settlement at a low level.

[0103] It should be noted that the above specific embodiments are exemplary. Those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also fall within the scope of the disclosure of the present invention and within the protection scope of the present invention. Those skilled in the art should understand that the description and drawings of the present invention are illustrative and do not constitute a limitation to the claims. The protection scope of the present invention is defined by the claims and their equivalents. The description of the present invention contains multiple inventive concepts. For example, "preferably" or "according to a preferred embodiment" indicate that the corresponding paragraphs disclose an independent concept. The applicant reserves the right to file divisional applications based on each inventive concept. Throughout the text, the features guided by "preferably" are only optional ways and should not be understood as being necessarily provided. Therefore, the applicant reserves the right to waive or delete the relevant preferred features at any time.

Claims

1. A prestressed non-circular shield structure, characterized in that It includes: A pipe section (100), which is configured as a rectangular-like reinforced concrete or steel fiber concrete structure, and includes a first pipe section block (101) and a second pipe section block (102); A middle partition wall (103), which is configured as a flat plate structure; A prestressing system, which includes a circumferential prestressing system (104) and a longitudinal prestressing system (105), wherein, The first pipe section block (101) and the second pipe section block (102) can be assembled to form the pipe section (100) by means of central rotation, and the assembled pipe section (100) can be applied with the circumferential prestressing system (104); multiple pipe sections (100) can be assembled with staggered joints and applied with the longitudinal prestressing system (105); the middle partition wall (103) can be installed between the first pipe section block (101) and the second pipe section block (102) in each pipe section (100).

2. The prestressed non-circular shield structure according to claim 1, wherein The first pipe section block (101) and / or the second pipe section block (102) are configured with side plates of different lengths on both sides, and positioning rods (201) and first positioning grooves (202) with matching dimensions are respectively arranged on both longitudinal joint surfaces; longitudinal bosses (203) and longitudinal grooves (204) are respectively arranged at the middle and both sides of both circumferential joint surfaces, and tooth grooves (205) penetrating longitudinally are arranged.

3. The prestressed non-circular shield structure according to claim 1, wherein The first pipe section block (101) and / or the second pipe section block (102) are provided with multiple circumferential prestressing ducts (301) along the circumferential width direction. Annular grooves (306) are arranged at the ends of the circumferential prestressing ducts (301). The circumferential prestressing ducts (301) include a circumferential section (302) located at the center of the cross-section of the pipe section (100), a lifting section (303) close to the longitudinal joint surface, and independent sections (304) whose two ends are respectively connected to the longitudinal joint surface and the arc-shaped tensioning groove (305).

4. The prestressed non-circular shield structure according to claim 3, characterized in that, After the pipe section (100) is assembled, the circumferential section (302) of the first pipe section block (101) is connected to the circumferential section (302) of the second pipe section block (102), the independent section (304) of the first pipe section block (101) is connected to the lifting section (303) of the second pipe section block (102), and the lifting section (303) of the first pipe section block (101) is connected to the independent section (304) of the second pipe section block (102), finally forming a circumferential prestressing duct (301) that penetrates circumferentially along the pipe section (100).

5. The prestressed non-circular shield structure according to claim 3, wherein, The circumferential prestressing duct (301) is a through duct that surrounds the pipe section (100) for one circle, and is lifted from the central cross-section of the pipe section (100) and led out from the inner arc surface in a cross manner near the tensioning position, and an arc-shaped tensioning groove (305) is arranged at the part led out from the inner arc surface.

6. The prestressed non-circular shield structure according to claim 1, characterized in that, The first pipe section block (101) and / or the second pipe section block (102) are provided with two longitudinal prestressing ducts (400) that penetrate the longitudinal boss (203) and the longitudinal groove (204) at the middle position, and first longitudinal tensioning grooves (401) and second longitudinal tensioning grooves (402) are arranged at both ends of the two longitudinal prestressing ducts (400).

7. The prestressed non-circular shield structure according to claim 3 or 6, characterized in that The circumferential prestressing system (104) and the longitudinal prestressing system (105) can respectively adopt a bonding tensioning scheme and a non-bonding tensioning scheme, wherein when the circumferential prestressing system (104) adopts the bonding tensioning scheme, an exhaust hole (404) is provided at the top position of the circumferential prestressing channel (301) on the first pipe segment block (101) and / or the second pipe segment block (102); when the longitudinal prestressing system (105) adopts the bonding tensioning scheme, a grouting hole (403) is provided on the first pipe segment block (101) and / or the second pipe segment block (102) and passes through the inner arc surface to the longitudinal prestressing channel (400).

8. The prestressed non-circular shield structure according to claim 1, wherein A reinforcing plate (501) and a plurality of positioning pins (502) are provided at the bottom of the tooth groove (205) of the first pipe segment block (101) and / or the second pipe segment block (102); the thickness of the middle partition wall (103) is smaller than the width of the tooth groove (205); and a plurality of second positioning grooves (503) matching the positioning pins (502) are provided at the bottom of the middle partition wall (103).

9. A construction method for a prestressed non-circular shield structure, characterized in that, It includes the following steps: Assembling the first pipe segment block (101) and the second pipe segment block (102) into a pipe segment (100); A pipe segment (100) is selected as a first pipe segment, and the circumferential prestressed strand (600) is sequentially inserted therein and tensioned and anchored at both ends, and then the first longitudinal prestressed strand (601) is inserted through the first longitudinal tensioning groove (401) of the first pipe segment and anchored at one end; Before assembling the second pipe section (1000), the first longitudinal prestressed strand (601) of the first pipe section is inserted into the second longitudinal tensioning groove (402) of the second pipe section (1000), and the second longitudinal prestressed strand (602) is inserted into the first longitudinal tensioning groove (401) of the second pipe section (1000) and anchored at one end; Assembling the second pipe segment (1000) and tensioning and anchoring the two ends of the circumferential prestressed strand (600), and then tensioning and anchoring the unanchored end of the first longitudinal prestressed strand (601); Before assembling the third pipe section (10000), the second longitudinal prestressed strand (602) is inserted into the second longitudinal tensioning groove (402) of the third pipe section (10000), and the first longitudinal prestressed strand (601) is inserted into the first longitudinal tensioning groove (401) of the third pipe section (10000) and anchored at one end; The third pipe section (10000) is assembled and both ends of the circumferential prestressed strand (600) are tensioned and anchored, and then the second longitudinal prestressed strand (602) is tensioned and anchored.

10. The construction method according to claim 9, characterized in that, It also includes the following steps: After the tunnel is opened, the middle partition wall (103) is installed, and the gap between the middle partition wall (103) and the tooth groove (205) is filled.

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