A prestressed non-circular shield structure and its construction method

Abstract

The present invention relates to a prestressed non-circular shield structure and a construction method thereof, and belongs to the technical field of top pipe tunnel structures. The shield structure includes a pipe segment, a middle partition wall and a prestressed system. The pipe segment includes a first pipe segment block and a second pipe segment block with completely identical structural forms; the prestressed system is divided into a circumferential prestressed system and a longitudinal prestressed system. During the construction process, the first pipe segment block and the second pipe segment block are assembled into a pipe segment through central rotation and longitudinal seam surface positioning rods, and a circumferential prestressed system is applied; then, multiple pipe segments are assembled into a continuous pipe segment using staggered seam assembly and circumferential seam surface mortise and tenon, and a longitudinal prestressed system is applied, and finally a middle partition wall is installed in the middle position of the pipe segment to form a shield structure. The present invention can effectively improve the mechanical properties of the shield structure, such as bearing capacity, stiffness, toughness, recoverability, and crack resistance, reduce structural defects such as water leakage, settlement, and large deformation, reduce later operation and maintenance costs, and significantly reduce the amount of steel bars used.

Description

Technical Field

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

[0002] Pipe jacking is a non-excavation, deep-dive pipe laying technique used in municipal construction. Its advantages include minimal or no impact on the surrounding environment, a smaller construction site, and low noise levels. Furthermore, it can penetrate deep underground, a feature unmatched by excavation.

[0003] The pipe segment is the lining structure of the pipe jacking structure. As the size of the excavation section increases, it is restricted by transportation conditions. Some pipe segments begin to adopt a block design. The existence of pipe segment joints reduces the overall performance of the pipe segment. When the pipe jacking structure is subjected to water and soil loads or surrounding construction disturbance loads, it is easy to increase structural deformation, cause structural cracks, joint leakage and other defects, affecting the durability and long-term operational stability of the pipe jacking structure.

[0004] CN109519175A discloses a rectangular top pipe and a construction method thereof, wherein the rectangular top pipe comprises a plurality of pipe sections which are aligned, stacked and fixed to each other in sequence, the pipe sections comprising an outer frame layer and an inner frame layer, both of which are in the shape of a rectangular frame; a gap is provided between the outer frame layer and the inner frame layer, and the gap forms a cavity layer, wherein 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 provided at the four corners of the cavity; matching tenons and mortises are respectively provided at both ends of the pipe section, and adjacent pipe sections are connected by the matching mortise and tenon of the tenons and mortise; the cavity and the gap between adjacent pipe sections are filled with a concrete layer.

[0005] CN103061782A discloses a large-section, rectangular, earth pressure-balanced jacking pipe segment for motor vehicle tunnels. With the jacking direction as the forward direction, the jacking pipe segment has grouting holes radially penetrating the pipe segment's wall at intervals along the circumference in the middle of its outer wall. Hoisting holes are provided in the middle of each of its four faces. Also, radial thixotropic grouting holes penetrating the pipe segment's wall are circumferentially spaced in front of the outer wall. The top of the jacking pipe segment is arched, and all four corners of the cross-section are arc-shaped chamfers. The invention also discloses a construction method for the 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, comprising: a pipe segment configured as a rectangular reinforced concrete or steel fiber concrete structure, comprising a first pipe segment block and a second pipe segment block; a central partition wall configured as a flat plate structure; and a prestressing system comprising 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 central rotation, and the assembled pipe segment can be subjected to a circumferential prestressing system; multiple pipe segments can be assembled in a staggered manner and subjected to a longitudinal prestressing system; and the central 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 two side plates of different lengths, and the longitudinal seam surfaces on both sides are respectively provided with positioning rods and first positioning grooves of matching sizes; the annular seam surfaces on both sides are respectively provided with longitudinal bosses and longitudinal grooves in the middle and on both sides, as well as tooth grooves running through the longitudinal direction.

[0012] According to a preferred embodiment, the first pipe segment block and / or the second pipe segment block are provided with multiple annular prestressed channels along the ring width direction, and annular grooves are provided at the ends of the annular prestressed channels. The annular prestressed channels include an annular section located at the center of the pipe segment cross section, a lifting section close to the longitudinal seam surface, and independent sections with both ends respectively connected to the longitudinal seam surface and the arc-shaped tensioning groove.

[0013] According to a preferred embodiment, after the pipe segments are assembled, the annular section of the first pipe segment block is connected to the annular section of the second pipe segment block, the independent section of the first pipe segment block is connected to the lifting section of the second pipe segment block, and the lifting section of the first pipe segment block is connected to the independent section of the second pipe segment block, ultimately forming an annular prestressed channel that runs through the annular direction of the pipe segment.

[0014] According to a preferred embodiment, the annular prestressed channel is a through channel surrounding the pipe segment, and is lifted from the central section of the pipe segment in a cross manner near the tensioning position and led out from the inner arc surface, and an arc-shaped tensioning groove is provided on the lead-out part of the inner arc surface.

[0015] According to a preferred embodiment, two longitudinal prestressed channels passing through the longitudinal boss and the longitudinal groove are provided in the middle position of the first pipe segment block and / or the second pipe segment block, and a first longitudinal tensioning groove and a second longitudinal tensioning groove are provided at both ends of the two longitudinal prestressed channels.

[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 and radial forces for the shield structure by applying annular prestress, making it a self-stabilizing structural system. As a result, the structural bearing capacity, stiffness, toughness, recoverability, crack resistance and other mechanical properties can be greatly improved, reducing pipe joint cracking and longitudinal seam leakage.

[0029] 2. The present invention applies longitudinal prestress to the shield structure by overlapping each section, which can ensure that all pipe sections are in a longitudinal prestressed state after assembly, thereby ensuring the longitudinal safety of the structure. At the same time, the longitudinal prestress and the mortise and tenon together serve as connecting parts of the annular seam surface, which can effectively improve the longitudinal stiffness and deformation resistance of the shield structure, and reduce longitudinal settlement and water leakage on the annular seam surface.

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

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

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

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

[0034] Figure 4 yes Figure 3 AA cross-sectional diagram;

[0035] Figure 5 yes Figure 3 BB cross-sectional diagram;

[0036] Figure 6 yes Figure 3 Schematic diagram of CC cross section;

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

[0038] Figure 8A 、 8B 8C and 8D are flow charts of the construction method of the present invention;

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

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

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

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

[0043] Figure 13 This is a comparison chart of the longitudinal top settlement of a prestressed non-circular shield structure and a common jacking pipe structure under unloading conditions;

[0044] Figure 14 This is a comparison chart of the longitudinal bottom settlement of the prestressed non-circular shield structure and the ordinary jacking pipe structure under unloading conditions.

[0045] Reference Signs List

[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 channel; 302: Circumferential section; 303: Lifting section; 304: Independent section; 305: Arc tensioning groove ; 306: annular groove; 400: longitudinal prestressed channel; 401: first longitudinal tensioning groove; 402: second longitudinal tensioning groove; 403: grouting hole; 404: exhaust hole; 501: reinforcement plate; 502: positioning pin; 503: second positioning groove; 600: circumferential prestressed strand; 601: first longitudinal prestressed strand; 602: second longitudinal prestressed strand; 1000: second pipe section; 10000: third pipe section. DETAILED DESCRIPTION

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

[0048] Figure 1 and Figure 2 The front and side views of a prestressed non-circular shield structure are shown.

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

[0050] Preferably, the pipe segment 100 is an independent ring unit of the shield structure, configured as a quasi-rectangular structure and can be prefabricated in a factory using reinforced concrete or steel fiber reinforced concrete. Furthermore, the cross-section of the quasi-rectangular pipe segment 100 is composed of several smooth, ductile curves, forming a closed outline similar to a rectangle. The four corners of the quasi-rectangular structure are rounded with the same or similar curvature radius, and the straight segments at the top and surrounding edges can also be configured as arcs with a curvature radius greater than the curvature radius of the rounded corners as needed. The combination of rounded corners and arcs in the quasi-rectangular structure can reduce stress concentration at the corners after the annular prestressed strands 600 are tensioned, facilitating stress transfer and ensuring structural safety. The pipe segment 100 can 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 detailed description will focus primarily on the first pipe segment block 101.

[0051] Preferably, the middle partition wall 103 is a flat plate structure, and its width is the same as the ring width of the pipe segment 100. For strata with relatively good rock and soil conditions surrounding the shield structure, the middle partition wall 103 is primarily used to separate the space on both sides and to partition functions, reducing vibration and noise during train operation. It does not need to be a load-bearing structure, and thinner energy-absorbing materials such as corrugated plates and shock-absorbing plates can be used to improve driving comfort. For strata with relatively poor rock and soil conditions surrounding the shield structure, in addition to fulfilling the above functions, the middle partition wall 103 also serves as a load-bearing structure, sharing the stratum pressure at the top and sides of the tunnel. Its thickness and reinforcement must meet design requirements.

[0052] Preferably, the prestressed system can provide additional internal force for the shield structure, which includes a circumferential prestressed system 104 and a longitudinal prestressed system 105, wherein the circumferential prestressed system 104 can provide axial force along the tangent direction of the pipe segment 100 and radial force pointing to the center of the circle, and the longitudinal prestressed system 105 can provide axial force along the circumferential width direction of the pipe segment 100 and vertical shear bearing capacity.

[0053] Preferably, during the construction of the shield structure, the second pipe segment block 102 at the bottom is first fixed, and then the first pipe segment block 101 is hoisted and fixed to the second pipe segment block 102 by rotating the center 180° to complete the assembly of the pipe segment 100; then the circumferential prestressing system 104 is applied to the pipe segment 100, at which time the pipe segment 100 can withstand water and soil loads; then the staggered assembly scheme is used to assemble the subsequent pipe segments 100, and the longitudinal prestressing system 105 is applied in sequence; finally, after the shield structure is penetrated, the middle partition wall 103 can be installed at the middle position of the pipe segment 100 at one time to form a shield structure.

[0054] Preferably, the specific operation of the overlapping 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 completing the longitudinal prestressing of the entire shield structure in a cycle.

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

[0056] Preferably, in order to achieve staggered assembly of the pipe segment 100 and improve the overall rigidity and waterproof performance of the structure, the side panels 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 seam surfaces of the same pipe segment 100 and the adjacent pipe segments 100 are not in the same plane.

[0057] To ensure accurate assembly of the pipe segment 100, a raised (concrete) locating rod 201 is preferably provided on one side of the longitudinal joint surface of each side of the first pipe segment block 101, and a first locating groove 202 matching the size of the locating rod 201 is provided on the other side. Compared to traditional PVE locating rods, the (concrete) locating rod 201 can be prefabricated directly into the longitudinal joint surface of the structure, resulting in lower cost, better shear resistance, and no installation required.

[0058] Preferably, to enhance the shear bearing capacity and longitudinal stiffness of the annular joint of pipe segment 100, a grooved tenon is provided on each side of the annular joint surface of pipe segment 100. These grooves comprise a longitudinal boss 203 and a longitudinal groove 204. The size and number of these grooves can be adjusted based on the buried depth of the shield structure. Generally, only one larger grooved tenon is provided in the center of the annular joint surface. In poorer ground conditions, multiple grooves can be provided in the center and on both sides of the annular joint surface. The formula for calculating the grooved tenon size is as follows:

[0059] ∑0.7f t b i h j >∑γ i h i ,

[0060] Where, f t b is the design value of tensile strength of concrete or steel fiber concrete; i is the width of the i-th tenon; h j is the height of the j-th tenon; γ i is the weight of the i-th layer of soil above the shield structure; h i is the thickness of the i-th layer of cover soil above the shield structure.

[0061] Preferably, in order to position and fix the middle partition wall 103 , the middle inner surfaces of the first pipe segment block 101 and the second pipe segment block 102 are designed with longitudinally penetrating tooth grooves 205 .

[0062] Figures 4 to 6 FIG. 3 shows a cross-sectional schematic diagram of the annular prestressed channel 301 of the first pipe segment 101. Figures 2 to 6 As shown, the first pipe segment 101 is provided with multiple annular prestressing channels 301 along the annular width. The spacing between these channels and their distance from the structural boundary should meet the design requirements for prestressed concrete structures. Annular grooves 306 are provided at the ends of the annular prestressing channels 301 located on the longitudinal joint surface. Water-expanding annular gaskets are placed in these grooves to seal the annular prestressing channels 301 and ensure 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 seam surface of the annular prestressed channel 301, that is, an annular groove 306 is set at the end of the annular prestressed channel 301. The outer diameter of the annular groove 306 is recommended to be 15 mm larger than the outer diameter of the prestressed channel 301, and the depth is recommended to be about 5 mm. An annular sealing gasket that expands when exposed to water (the expansion rate after contact with water can be close to 400%) is placed in the annular groove 306. The inner diameter of the annular sealing gasket is recommended to be 5 mm larger than the outer diameter of the annular prestressed channel 301, and the outer diameter is recommended to be slightly smaller than the outer diameter of the annular groove 306, such as less than 1 mm. The thickness should be greater than 5 mm, and 6-7 mm is recommended.

[0063] Preferably, for the pipe segment 100, the annular prestressed channel 301 is a through channel that surrounds the pipe segment 100 and is lifted from the central section of the pipe segment 100 in a cross-shaped manner near the tensioning position and led out from the inner arc surface. The inner arc surface lead-out portion is provided with an arc-shaped tensioning groove 305 to provide tensioning and anchoring space for the annular prestressed strands 600. Since the tensioning position of the annular prestressed channel 301 is set near the longitudinal seam surface, two channels will appear on the same cross section of each annular prestressed channel 301 near the arc-shaped tensioning groove 305 on the first pipe segment block 101, such as Figure 4 The right side and Figure 5The two independent channel sections include the first channel consisting of the annular section 302 located at the center of the pipe section 100 cross section and the raised section 303 near the longitudinal joint surface, and the second channel formed by the independent section 304 whose ends are connected to the longitudinal joint surface and the arc-shaped tensioning groove 305. The independent section 304 is a straight channel, perpendicular to the tensioning surface of the arc-shaped tensioning groove 305. The length of the independent section 304 is recommended to be greater than 1m. There is a large angle between the annular section 302 and the independent section 304, and they need to be connected by a channel section with large curvature, namely the raised section 303. The curvature radius of the raised section 303 is related to many factors such as the curvature of the pipe section 100 in the area, the length of the independent section 304, and the channel diameter. It requires targeted design. Generally speaking, the curvature radius of the raised section 303 should be greater than 1m. The lifting height of the raised section 303 can be determined after determining the length of the independent section 304 and the curvature radius of the raised section 303. The curvature radius of raised section 303 (greater than 1m) is set to prevent stress concentration in this area after the hoop prestressed strands 600 are tensioned. Given that the length of independent section 304 must be greater than 1m, raised section 303 may also include a (straight) independent section 304 near the joint surface.

[0064] Preferably, since the structural types of the first pipe segment block 101 and the second pipe segment block 102 are completely identical, after being assembled into the pipe segment 100 by rotating the center 180°, the annular section 302 of the first pipe segment block 101 is connected to the annular section 302 of the second pipe segment block 102, the independent section 304 of the first pipe segment block 101 is connected to the lifting section 303 of the second pipe segment block 102, and the lifting section 303 of the first pipe segment block 101 is connected to the independent section 304 of the second pipe segment block 102, finally forming an annular prestressed channel 301 that runs circumferentially along the pipe segment 100.

[0065] Preferably, the area of ​​the annular prestressing channel 301 should be greater than three times the cross-sectional area of ​​the annular prestressing strands 600, considering that misalignment during pipe jacking assembly can cause alignment tolerances between the independent section 304 and the lifting section 303. This significant difference in area provides ample room for misalignment, ensuring that misalignment during assembly does not affect the threading efficiency of the annular prestressing strands 600. Furthermore, the annular prestressing force significantly increases the pressure on the longitudinal joint surface of the shield structure. The design of the positioning rods 201 reduces assembly errors, minimizing misalignment on the longitudinal joint surface.

[0066] Preferably, the longitudinal prestressing channels 400 of the first pipe segment 101 are located at the rabbet in the middle of the annular joint, forming two longitudinally extending channels. To ensure the tension of the longitudinal prestress, a first longitudinal tensioning groove 401 and a second longitudinal tensioning groove 402 are provided on both the longitudinal boss 203 and the longitudinal groove 204 at the rabbet. The first and second longitudinal tensioning grooves 401 and 402 have identical dimensions and are circular or square.

[0067] Preferably, both the circumferential prestressing system 104 and the longitudinal prestressing system 105 can adopt a bonded tensioning scheme or a non-bonded tensioning scheme. When the circumferential prestressing system 104 adopts the bonded tensioning scheme, an exhaust hole 404 needs to be set at the top position of the circumferential prestressing channel 301 of the first pipe segment block 101. Grouting is performed through the arc-shaped tensioning groove 305. The gas in the circumferential prestressing channel 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, a grouting hole 403 is required to be set on the first pipe segment block 101, which extends from the inner arc surface to the longitudinal prestressing channel 400. The grouting hole 403 should be located at both ends of the longitudinal prestressing channel 400. The grouting hole 403 can also serve as an exhaust hole.

[0068] Preferably, multiple pipe segments 100 are used in the longitudinal direction of the prestressed non-circular shield structure as a longitudinal prestressed section, wherein, during the grouting process, grouting is performed from the first grouting hole 403 of the longitudinal prestressed section, exhaust is performed from the last grouting hole 403, and the multiple grouting holes 403 in the middle are blocked.

[0069] Figure 7 The diagram shows the structure of the middle partition wall 103. Multiple second positioning slots 503 are provided on both the upper and lower surfaces of the middle partition wall 103. The middle partition wall 103 is installed within the tooth groove 205 of the first pipe segment block 101. A reinforcement plate 501 and multiple positioning pins 502 are provided at the bottom of the tooth groove 205 of the first pipe segment block 101. The reinforcement plate 501 distributes the load of the middle partition wall 103 on the bottom of the tooth groove 205, preventing damage to the longitudinal prestressed channel 400. The second positioning slots 503 and positioning pins 502 serve to position and secure 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 section 100, the thickness of the middle partition wall 103 is smaller than the width of the tooth groove 205, and the height of the protrusion 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 for a prestressed non-circular shield structure, by which the above prestressed non-circular shield structure can be obtained. Preferably, the construction method may include the following steps:

[0072] S1. Prefabricate the first pipe segment 101 and the second pipe segment 102 in batches in the factory, including processing the steel cage, installing the annular prestressed duct 301 and the longitudinal prestressed duct 400, pouring concrete, and performing maintenance. Before assembling the pipe segment 100, install an annular sealing gasket in the annular groove 306.

[0073] S2, fix the second pipe segment block 102 at the bottom, hoist the first pipe segment block 101, rotate it 180 degrees, and then position and fix it with 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, such as Figure 8A , each annular prestressed duct 301 is sequentially penetrated by an annular prestressed strand 600, and a bidirectional synchronous graded tensioning scheme is adopted for tensioning and anchoring at both ends to complete the annular prestressing of the pipe segment 100, and then the first longitudinal prestressed strand 601 is penetrated by the first longitudinal tensioning groove 401 of the pipe segment 100 and anchored at one end, wherein the length of the first longitudinal prestressed strand 601 must be greater than twice the sum of the annular width of the pipe segment 100 and the reserved anchoring length;

[0075] S4, such as Figure 8B Before assembling the second pipe segment 1000, insert the first longitudinal prestressed strand 601 of the pipe segment 100 into the second longitudinal tensioning groove 402 of the second pipe segment 1000, and insert the second longitudinal prestressed strand 602 through the first longitudinal tensioning groove 401 of the second pipe segment 1000 and anchor one end thereof. The second longitudinal prestressed strand 602 has the same length as the first longitudinal prestressed strand 601.

[0076] S5, such as Figure 8C The second pipe segment 1000 is positioned and fixed to the pipe segment 100 via the longitudinal boss 203 and the longitudinal groove 204, completing the assembly of the second pipe segment 1000. The two ends of the annular prestressed strands 600 of the second pipe segment 1000 are tensioned and anchored. Then, the first longitudinal prestressed strands 601 are tensioned and anchored on the annular seam surface of the second pipe segment 1000 that is not in contact with the pipe segment 100, completing the application of longitudinal prestress between the pipe segment 100 and the second pipe segment 1000.

[0077] S6, such as Figure 8D Before assembling the third pipe segment 10000, insert the second longitudinal prestressed strand 602 into the second longitudinal tensioning groove 402 of the third pipe segment 10000, and insert the first longitudinal prestressed strand 601 into the first longitudinal tensioning groove 401 of the third pipe segment 10000 and anchor one end thereof;

[0078] S7, assembling the third pipe segment 10000 and tensioning and anchoring the two ends of the circumferential prestressed strand 600, and then tensioning and anchoring the unanchored ends of the second longitudinal prestressed strand 602, completing the application of longitudinal prestress between the second pipe segment 1000 and the third pipe segment 10000;

[0079] S8, repeating steps S6 and S7 to complete the construction of subsequent pipe segments 100;

[0080] S9. 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.

[0081] Preferably, if a bonded tensioning scheme is adopted, after the tunnel is completed, the annular prestressed duct 301 and the longitudinal prestressed duct 400 are sequentially grouted, and the intermediate partition wall 103 is installed and the gap between the intermediate partition wall 103 and the tooth groove 205 is filled. If a non-bonded tensioning scheme is adopted, the intermediate partition wall 103 is directly installed and the gap between the intermediate partition wall 103 and the tooth groove 205 is filled after the tunnel is completed.

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

[0083] Midas software was used to build a 3D solid model of a common pipe jacking structure and a prestressed non-circular shield structure. The pipe segment width of the common 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 is 1.5m. The model has a total of 10 pipe segments. The longitudinal joint surface of the common pipe jacking structure is connected by 2 M30 bolts, and the longitudinal joint surface is connected by 8 M30 bolts. Each annular prestressed channel of the prestressed non-circular shield structure uses 6 15.2mm prestressed strands with an area of ​​840mm. 2 Each longitudinal prestressed channel uses 8 15.2mm prestressed strands with an area of ​​1120mm 2 The tension control stress is 1320MPa. Positioning rods 201 and concave and convex tenons are set on the longitudinal seam surface and the annular seam surface respectively.

[0084] Both the ordinary jacking pipe structure and the prestressed non-circular shield structure use C50 concrete with an elastic modulus of 3.45×10 7 kN / m 2 , Poisson's ratio is 0.2, and the bulk density is 25kN / m 3 The normal stiffness coefficient of the annular seam surface and the longitudinal seam 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 strands are tensioned with a bonded structure. The friction coefficient of the prestressed duct wall is 0.2, and the influence coefficient of local deviation per meter of the prestressed duct on friction is 0.0015. The deformation of the tensioning end anchor and the shrinkage of the prestressed tendon are 6mm. The elastic modulus of the prestressed strands is 195GPa.

[0085] The tunnel jacking structure was buried at a depth of 10m. A uniformly distributed load of 0.2MPa was applied to the top and bottom of both the conventional tunnel jacking structure and the prestressed non-circular shield structure, and a uniformly distributed load of 0.12MPa was applied to the left and right sides. Foundation springs with a normal stiffness of 900kN / m and a tangential stiffness of 300kN / m were used to simulate the interaction between the tunnel jacking structure and the stratum.

[0086] The loading process of the ordinary pipe jacking structure under water and soil loads is as follows: ① Establish a three-dimensional solid model of the multi-ring ordinary pipe jacking structure; ② Apply loads on all four sides at the same time.

[0087] The loading process of the prestressed non-circular shield structure under water and soil 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 tension control stress; ③ Establish longitudinal prestressed strands and apply tension control stress; ④ Apply loads on all sides simultaneously.

[0088] Figure 9 and Figure 10 The axial force and bending moment distributions of a prestressed non-circular shield structure and a conventional pipe-jacking structure under water and soil loads are shown. Under water and soil loads, the axial force of the conventional pipe-jacking structure ranges from 1778.9 kN to 1227.8 kN, while that of the prestressed non-circular shield structure ranges from 2203.1 kN to 2998.9 kN. Under water and soil loads, the bending moment of the conventional pipe-jacking structure ranges from -1194.1 kN·m to 664.5 kN·m, while that of the prestressed non-circular shield structure ranges from -1215.3 kN·m to 736.8 kN·m. Compared to the conventional pipe-jacking structure, the prestressed non-circular shield structure exhibits a 70.6% increase in axial force and a 7.4% increase in bending moment.

[0089] Figure 11 and Figure 12 The horizontal and vertical deformation distributions of the prestressed non-circular shield structure and the conventional jacking pipe structure under water and soil loads are shown. Under water and soil loads, the maximum horizontal deformations of the conventional jacking pipe structure and the prestressed non-circular shield structure are 14.2 mm and 10.2 mm, respectively, and the vertical deformations are 19.7 mm and 18.3 mm, respectively. Compared to the conventional jacking pipe structure, the horizontal deformation of the prestressed non-circular shield structure is reduced by 28.2%, and the vertical deformation is reduced by 7.1%. In addition, the conventional jacking pipe structure has significant misalignment at the longitudinal joint surface.

[0090] Based on the axial force and bending moment distribution of prestressed non-circular shield structure and ordinary jacking pipe structure under water and soil load, the reinforcement calculation is carried out using the current national standard "Concrete Structure Design Standard" GB / T 50010. The inner and outer main reinforcement areas of the prestressed non-circular shield structure are 9651mm 2 and 2290mm 2The inner and outer main reinforcement areas of ordinary jacking pipe structures are 11259mm 2 and 4084mm 2 Compared with the ordinary jacking pipe structure, the main reinforcement area of ​​the prestressed non-circular shield structure is reduced by 22.2%.

[0091] This means that prestressed non-circular shield structures offer greater axial force, less deformation, and lower steel requirements, resulting in a more rational stress distribution than conventional jacking pipe structures. Furthermore, the design of the longitudinal joint positioning rods 201 and the increased pressure provided by the circumferential prestress effectively reduce the amount of longitudinal joint misalignment, thereby improving the structural waterproofing.

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

[0093] The design parameters and surrounding water and soil loads of the prestressed non-circular shield structure and ordinary jacking pipe structure under unloading conditions are consistent with those mentioned above.

[0094] The loading process of the ordinary pipe jacking structure under unloading conditions is as follows: ① Establish a three-dimensional solid model of the multi-ring ordinary pipe jacking structure; ② Apply loads on all four sides simultaneously; ③ The foundation spring stiffness within 90° of the bottom of the middle four-ring pipe jacking structure is reduced to 0, and the load is reduced 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 annular prestressed strands and apply tension control stress; ③ Establish longitudinal prestressed strands and apply tension control stress; ④ Apply loads on all sides at the same time; ⑤ The foundation spring stiffness within 90° of the bottom of the middle four-ring jacking structure is reduced to 0 and the load is reduced to 0.1 MPa.

[0096] Figure 13 and Figure 14 The longitudinal top and bottom settlements of a prestressed non-circular shield structure and a conventional pipe jacking structure under unloading conditions are shown. The maximum settlements of both structures under unloading conditions are located in the middle of the longitudinal direction, with maximum top settlements of 0.26mm and 1.68mm, respectively, and maximum bottom settlements of 2.90mm and 6.65mm, respectively. Compared to the conventional pipe jacking structure, the maximum top settlement of the prestressed non-circular shield structure was reduced by 84.5%, and the maximum bottom settlement was reduced by 56.4%.

[0097] That is, the prestressed non-circular shield structure has higher longitudinal stiffness, which can greatly reduce the longitudinal settlement of the 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 amount of misalignment at the joints. Conventional jacking pipe structures are prone to significant longitudinal misalignment under load due to the insufficient rigidity of their bolted connection method (two M30 bolts on the longitudinal joint surface and eight M30 bolts on the annular joint surface). However, the prestressed non-circular shield structure, through the interlocking design of the positioning rod 201 and the groove, evens out the contact pressure on the longitudinal joint surface, reducing the maximum horizontal deformation from 14.2mm to 10.2mm (a 28.2% reduction). Furthermore, the boss and groove design on the annular joint surface further reduces the vertical deformation difference (from 19.7mm to 18.3mm) by increasing the anti-slip ability of the contact surface (friction coefficient 0.3). This improvement in geometric precision not only improves the integrity of the structure but also effectively prevents the formation of water seepage paths by reducing micro-displacements at the joints, thereby improving waterproofing performance.

[0101] 3. The design of the lifting section 303 and independent section 304 of the present invention improves the uniformity of prestress distribution by optimizing the layout of the prestressed strands. Specifically, the lifting section 303 adjusts the relative position of the strands and concrete to concentrate the prestress in the tensile area, while the independent section 304 avoids stress concentration by reducing local deviation of the duct (influence coefficient 0.0015 / m). This optimization directly reduces the tensile stress demand of the concrete, reducing the main reinforcement area from 11,259 mm² inside and 4,084 mm² outside of a conventional jacking pipe structure to 9,651 mm² inside and 2,290 mm² outside of the prestressed structure (a 22.2% reduction). Furthermore, the annular groove 306 design enhances the bond between the prestressed strands and concrete (elastic modulus 195 GPa), improving prestress transmission efficiency and increasing the axial force from 1,778.9 kN in a conventional structure to 2,203.1 kN. This result shows that the geometric optimization of prestressed ducts and the matching of material properties are key factors in achieving structural lightweight and economical performance.

[0102] 4. The intermediate partition wall 103 of the present invention, which is a flat plate structure, forms a synergistic effect with the prestressed system by providing lateral restraint. The rigid structure of the intermediate partition wall 103 (C50 concrete, elastic modulus 3.45×10 7 kN / m²) disperses the localized forces of water and soil loads laterally, reducing vertical deformation differences (from 19.7 mm to 18.3 mm). This effect is achieved through the combined action of the partition wall 103 and the prestressed strands: the circumferential prestressed strands 600 limit the lateral displacement of the partition wall 103 through a compressive stress field, while the partition wall 103, through rigid support, reversely enhances the stability of the prestressed system. This bidirectional constraint mechanism is particularly significant under unloading conditions. For example, when the base spring stiffness drops to zero, the lateral stiffness of the partition wall 103 can still maintain the integrity of the structure, thereby keeping longitudinal settlement at a low level.

[0103] It should be noted that the above-mentioned specific embodiments are exemplary, and those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also belong to the disclosure scope of the present invention and fall within the protection scope of the present invention. Those skilled in the art should understand that the present invention specification and its drawings are illustrative and do not constitute a limitation on the claims. The scope of protection of the present invention is defined by the claims and their equivalents. The present invention specification contains multiple inventive concepts, such as "preferably" or "according to a preferred embodiment", which means that the corresponding paragraph discloses an independent concept, and the applicant reserves the right to file a divisional application based on each inventive concept. Throughout the text, the features guided by "preferably" are only an optional method and should not be understood as having to be set. Therefore, the applicant reserves the right to abandon or delete the relevant preferred features at any time.

Claims

1. A prestressed non-circular shield structure, characterized in that: It includes: A pipe segment (100) is configured as a rectangular reinforced concrete or steel fiber reinforced concrete structure, comprising a first pipe segment block (101) and a second pipe segment block (102); a middle partition wall (103) configured as a flat plate structure; A prestressing system comprising a hoop prestressing system (104) and a longitudinal prestressing system (105), wherein: The first pipe segment block (101) and the second pipe segment block (102) can be assembled into a pipe segment (100) by central rotation, and the assembled pipe segment (100) can be applied with a circumferential prestressing system (104); multiple pipe segments (100) can be assembled in a staggered manner and applied with a longitudinal prestressing system (105); the middle partition wall (103) can be installed between the first pipe segment block (101) and the second pipe segment block (102) in each pipe segment (100); The first pipe segment block (101) and / or the second pipe segment block (102) are provided with two side plates of different lengths, and the longitudinal seam surfaces on both sides are respectively provided with positioning rods (201) and first positioning grooves (202) of matching sizes; the annular seam surfaces on both sides are respectively provided with concave and convex tenons at the middle and two side positions, which include longitudinal bosses (203) and longitudinal grooves (204), as well as tooth grooves (205) running through in the longitudinal direction. After the first pipe segment block (101) and the second pipe segment block (102) are assembled into a pipe segment (100), the longitudinal seam surfaces of the same pipe segment (100) and the adjacent pipe segments (100) are not in the same plane. The formula for calculating the size of the tenon and mortise is as follows: ∑0.7f t b i h j >∑γ i h i , Where, f t b is the design value of tensile strength of concrete or steel fiber concrete; i is the width of the i-th tenon; h j is the height of the j-th tenon; γ i is the weight of the i-th layer of soil above the shield structure; h i is the thickness of the i-th layer of cover soil above the shield structure.

2. The prestressed non-circular shield structure according to claim 1, characterized in that: The first pipe segment block (101) and / or the second pipe segment block (102) are provided with a plurality of annular prestressed channels (301) along the annular width direction, and an annular groove (306) is provided at the end of the annular prestressed channel (301). The annular prestressed channel (301) includes an annular section (302) located at the center of the cross section of the pipe segment (100), a raised section (303) close to the longitudinal seam surface, and an independent section (304) with two ends respectively connected to the longitudinal seam surface and the arc-shaped tensioning groove (305).

3. The prestressed non-circular shield structure according to claim 2, characterized in that: After the pipe segment (100) is assembled, the annular section (302) of the first pipe segment block (101) is connected to the annular section (302) of the second pipe segment block (102), the independent section (304) of the first pipe segment block (101) is connected to the lifting section (303) of the second pipe segment block (102), and the lifting section (303) of the first pipe segment block (101) is connected to the independent section (304) of the second pipe segment block (102), ultimately forming an annular prestressed channel (301) that is circumferentially connected to the pipe segment (100).

4. The prestressed non-circular shield structure according to claim 2, characterized in that: The annular prestressed channel (301) is a through channel surrounding the pipe segment (100) and is lifted from the central cross section of the pipe segment (100) in a cross manner near the tensioning position and drawn out from the inner arc surface, and an arc-shaped tensioning groove (305) is provided at the drawn-out portion of the inner arc surface.

5. The prestressed non-circular shield structure according to claim 1, characterized in that: Two longitudinal prestressed channels (400) passing through the longitudinal boss (203) and the longitudinal groove (204) are provided at the middle position of the first pipe segment block (101) and / or the second pipe segment block (102), and both ends of the two longitudinal prestressed channels (400) are provided with a first longitudinal tensioning groove (401) and a second longitudinal tensioning groove (402).

6. The prestressed non-circular shield structure according to claim 2 or 5, 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).

7. The prestressed non-circular shield structure according to claim 1, characterized in that: 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).

8. A construction method using the prestressed non-circular shield structure according to any one of claims 1 to 7, 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.

9. The construction method according to claim 8, 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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