Underground space large-section parallel pipe jacking structure and construction method thereof

Abstract

This invention relates to the field of pipe jacking construction technology, and discloses a large-section parallel pipe jacking structure for underground space and its construction method, comprising multiple first pipe sections, multiple second pipe sections, and multiple frame columns; the first and second pipe sections are arranged side by side, and each first pipe section includes a top segment, an outer segment, a bottom segment, and an inner segment connected circumferentially in sequence, with the inner segment detachably connected to the top and bottom segments; multiple frame columns are arranged in the first and second pipe sections and are longitudinally spaced, with the portion of the top segment corresponding to the frame column forming a top precast beam segment, and a top post-cast beam segment provided between the top precast beam segment and the upper end of the frame column, forming a top composite beam; a first tension steel strand runs through the top precast beam segments of the multiple first pipe sections and the top precast beam segments of the multiple second pipe sections, and a second tension steel strand runs through the top post-cast beam segments of the multiple first pipe sections and the top post-cast beam segments of the multiple second pipe sections.

Description

Technical Field

[0001] This invention relates to the field of pipe jacking construction technology, and in particular to a large-section parallel pipe jacking structure for underground spaces and its construction method. Background Technology

[0002] In recent years, the pipe jacking method has been commonly used in the construction of urban rail transit systems for the main structure of large-section subway stations. Pipe jacking is a trenchless technology that does not damage existing pipelines and structures during construction and has minimal impact on surface traffic and the surrounding environment.

[0003] For example, Chinese invention patent application CN116025376A, published on April 28, 2023, discloses a structural system and construction method for a double-tunnel combined pipe jacking tunnel railway station. This structural system includes: a first and second pipe jacking tube arranged adjacent to each other, a reinforced concrete notched top beam, a reinforced concrete notched bottom beam, a central column, and a central plate. Each pipe jacking tube is C-shaped, with two pipe jacking tubes arranged horizontally adjacent to each other and their openings facing each other. Each pipe jacking tube is formed by several pipe jacking rings connected longitudinally. Each pipe jacking ring includes a precast segment top plate, a precast segment bottom plate, a precast segment outer wall, and a supporting beam; the central column is used to connect the top and bottom ends of the openings of the two pipe jacking tubes together; the reinforced concrete notched top beam is used to connect the top joints of the two pipe jacking tubes together; and the reinforced concrete notched bottom plate is used to connect the bottom joints of the two pipe jacking tubes together.

[0004] However, in the existing structural system of the double-tunnel combined pipe jacking tunnel station, when the top beam is connected to the top joint of the two pipes, the top beam protrudes downwards and occupies the internal space of the pipe section, making it difficult to form a flat-top large space; in addition, it is difficult to reliably connect the subsequently poured top beam to the top of the two pipes, resulting in poor integrity of the structural system composed of the two pipes. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that when the existing top beam is connected to the top joint of the two jacking pipes, the top beam protrudes downwards and occupies the internal space of the pipe section, making it difficult to form a flat-top large space; in addition, it is difficult to reliably connect the top beam of the subsequently poured top beam to the top of the two jacking pipes, resulting in poor integrity of the structural system composed of the two jacking pipes.

[0006] To address the aforementioned technical problems, this invention provides a technical solution for a large-section parallel pipe jacking structure in underground spaces:

[0007] The underground space large-section parallel pipe jacking structure includes multiple first pipe sections, multiple second pipe sections, and multiple frame columns. Multiple first pipe sections are connected in sequence along the longitudinal direction to form a first longitudinal channel, and multiple second pipe sections are connected in sequence along the longitudinal direction to form a second longitudinal channel.

[0008] The first pipe section and the second pipe section have the same structure and are arranged side by side. The first pipe section includes a top pipe segment, an outer pipe segment, a bottom pipe segment and an inner pipe segment connected in sequence in the circumferential direction. The inner pipe segment is detachably connected to the top pipe segment and the bottom pipe segment respectively.

[0009] Multiple frame columns are arranged in the first pipe section and the second pipe section and are distributed at intervals along the longitudinal direction. The top pipe segment corresponding to the frame column forms a top precast beam segment. A top post-cast beam segment is provided between the top precast beam segment and the upper end of the frame column. The top precast beam segment and the top post-cast beam segment form a top composite beam.

[0010] A first tension steel strand is connected through the top precast beam segments of the plurality of first pipe sections and the top precast beam segments of the plurality of second pipe sections. A second tension steel strand is connected through the top post-cast beam segments of the plurality of first pipe sections and the top post-cast beam segments of the plurality of second pipe sections.

[0011] Furthermore, the portion of the bottom segment corresponding to the frame column forms a bottom precast beam segment, and a bottom post-cast beam segment is provided between the bottom precast beam segment and the lower end of the frame column. The bottom precast beam segment and the bottom post-cast beam segment form a bottom composite beam.

[0012] A first tension steel strand is connected through the bottom precast beam segments of the plurality of first pipe sections and the bottom precast beam segments of the plurality of second pipe sections. A second tension steel strand is connected through the bottom post-cast beam segments of the plurality of first pipe sections and the bottom post-cast beam segments of the plurality of second pipe sections.

[0013] Furthermore, the first tensioning steel strand is a negative moment prestressed steel strand, and the longitudinal middle part of the first tensioning steel strand is arched outward; the second tensioning steel strand is a positive moment prestressed steel strand, and the second tensioning steel strand is extended horizontally along the longitudinal direction.

[0014] Furthermore, multiple first tensioning steel strands are arranged at intervals along the longitudinal direction, and multiple second tensioning steel strands are arranged at intervals along the longitudinal direction, with the first tensioning steel strands and the second tensioning steel strands partially overlapping.

[0015] Furthermore, at least two of the first tensioning steel strands are arranged side by side in the top precast beam segment and the bottom precast beam segment, and at least two of the second tensioning steel strands are arranged side by side in the top post-cast beam segment and the bottom post-cast beam segment, and the number of the first tensioning steel strands is greater than the number of the second tensioning steel strands.

[0016] Furthermore, the top composite beam is a T-shaped composite beam, and the top post-cast beam segment is located in the lower middle part of the top precast beam segment, with the lower side of the top precast beam segment flush with the lower surface of the top tube segment.

[0017] Furthermore, the bottom composite beam is an L-shaped composite beam, and the bottom post-cast beam segment is located at the upper end of the bottom precast beam segment, with the upper side of the bottom precast beam segment flush with the upper surface of the bottom segment.

[0018] Furthermore, corrugated pipes are pre-embedded inside the top precast beam segment, the bottom precast beam segment, the top post-cast beam segment, and the bottom post-cast beam segment, respectively, and the first tensioning steel strand and the second tensioning steel strand are respectively inserted through the corrugated pipes.

[0019] Furthermore, the lateral distance between the frame column and the outer tube segment is D1, and the lateral distance between the frame column and the inner tube segment is D2, satisfying D2≤D1≤3*D2; a temporary steel column can be detachably installed between the top tube segment and the bottom tube segment.

[0020] To address the aforementioned technical problems, this invention provides a technical solution for the construction of large-section parallel pipe jacking structures in underground spaces:

[0021] The construction method for large-section parallel pipe jacking structures in underground spaces includes the following steps:

[0022] S1. When prefabricating tunnel segments, corrugated pipes are pre-embedded in the top and bottom tunnel segments respectively;

[0023] S2. Before jacking, the first and second pipe sections are spliced ​​and assembled, and temporary steel columns are installed inside the first and second pipe sections.

[0024] S3. The first and second pipe sections are jacked up using a dual-tunnel parallel method.

[0025] S4. After the jacking is completed, the first tension steel strand is connected through the corrugated pipes of the top and bottom segments, negative bending moment prestress is applied to the first tension steel strand, it is anchored and grouted within 24 hours.

[0026] S5. Remove the temporary steel columns and inner segments inside the first and second pipe sections;

[0027] S6. Tie the reinforcing bars of the top and bottom post-cast beam segments, and pre-embed the corrugated pipes, the second tension steel strands, and the fixed end anchors.

[0028] S7. Pour concrete for the top and bottom post-cast beam segments. After the concrete strength, modulus of elasticity and age meet the standards, apply positive bending moment prestress to the second tensioned steel strand, anchor it and grout within 24 hours.

[0029] S8. Perform post-casting anchor sealing treatment on the tensioning slots of the top and bottom post-cast beam segments.

[0030] Compared with the prior art, the beneficial effects of the parallel pipe jacking structure and construction method for large cross-section underground space of the present invention are as follows: The parallel pipe jacking structure for large cross-section underground space adopts a structural design of multiple first pipe sections, multiple second pipe sections and multiple frame columns. Multiple first pipe sections are connected in sequence along the longitudinal direction to form a first longitudinal channel, and multiple second pipe sections are connected in sequence along the longitudinal direction to form a second longitudinal channel. The first pipe sections and second pipe sections are arranged in parallel, and the parallel jacking of the two pipe sections reduces the impact of ground disturbance and improves construction efficiency. After the jacking construction, the inner pipe segments of the first pipe section and the inner pipe segments of the second pipe section can be removed, so that the first longitudinal channel and the second longitudinal channel are connected to form a large cross-section overall space.

[0031] In this structure, multiple frame columns are set within the first and second pipe sections and spaced longitudinally. The portion of the top pipe segment corresponding to the frame columns forms a precast top beam segment. A post-cast top beam segment is provided between the precast top beam segment and the upper end of the frame column, forming a composite top beam. The post-cast top beam segment connects the top segments of the multiple first and second pipe sections into a longitudinally continuous load-bearing structure, ensuring reliable connection between the composite top beam and the top pipe segments. Compared to existing structures where the top beam is connected to the top of both jacking pipes, this jacking pipe structure reliably connects the multiple first and second pipe sections through internal composite top beams. The precast top beam segment, as part of the top pipe segment, avoids the downward protrusion of longitudinal beams that would occupy internal space within the pipe section, thus creating a flat-topped large space and improving the clearance of the underground structure.

[0032] In addition, first tension steel strands are used to connect the top precast beam segments of multiple first pipe sections and the top precast beam segments of multiple second pipe sections. Second tension steel strands are also used to connect the top post-cast beam segments of multiple first pipe sections and the top post-cast beam segments of multiple second pipe sections. By applying prestress to the top precast beam segments of multiple pipe sections using the first tension steel strands and to the top post-cast beam segments of multiple pipe sections using the second tension steel strands, the longitudinal integrity of the pipe jacking structure is improved. The prestressed structure has a strong load-bearing capacity and can reduce reinforcement requirements while meeting the load-bearing capacity requirements during stress system transformation. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the cross-section of the large-section parallel pipe jacking structure in the underground space without the temporary steel columns being removed, as described in this embodiment of the invention.

[0034] Figure 2 This is a schematic cross-sectional view of the large-section parallel pipe jacking structure in the underground space in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the longitudinal section of the large-section parallel pipe jacking structure in the underground space in an embodiment of the present invention;

[0036] In the diagram: 1-First pipe section, 10-First longitudinal channel, 11-Top pipe segment, 111-Top precast beam segment, 112-Top post-cast beam segment, 12-Outer pipe segment, 13-Bottom pipe segment, 131-Bottom precast beam segment, 132-Bottom post-cast beam segment, 14-Inner pipe segment, 15-Top composite beam, 16-Bottom composite beam, 2-Second pipe section, 20-Second longitudinal channel, 3-Frame column, 40-Corrugated pipe, 41-First tensioning steel strand, 42-Second tensioning steel strand, 43-Fixed end anchor, 5-Temperature steel column. Detailed Implementation

[0037] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0038] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise" used to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] like Figures 1 to 3As shown in the figure, an underground space large-section parallel pipe jacking structure according to an embodiment of the present invention includes multiple first pipe sections 1, multiple second pipe sections 2, and multiple frame columns 3. The multiple first pipe sections 1 are connected in sequence along the longitudinal direction to form a first longitudinal channel 10, and the multiple second pipe sections 2 are connected in sequence along the longitudinal direction to form a second longitudinal channel 20. The first pipe sections 1 and the second pipe sections 2 have the same structure and are arranged side by side. The first pipe section 1 includes a top pipe segment 11, an outer pipe segment 12, a bottom pipe segment 13, and an inner pipe segment 14 connected in sequence around the circumference. The inner pipe segment 14 is detachably connected to the top pipe segment 11 and the bottom pipe segment 13, respectively.

[0042] Multiple frame columns 3 are arranged in the first pipe section 1 and the second pipe section 2 and are distributed longitudinally at intervals. The top pipe segment 11 corresponding to the frame column 3 forms the top precast beam segment 111. The top precast beam segment 111 and the top post-cast beam segment 112 are provided between the top precast beam segment 111 and the upper end of the frame column 3. The top precast beam segment 111 and the top post-cast beam segment 112 form the top composite beam 15. The top precast beam segments 111 of the multiple first pipe sections 1 and the top precast beam segments 111 of the multiple second pipe sections 2 are connected through the first tension steel strand 41. The top post-cast beam segments 112 of the multiple first pipe sections 1 and the top post-cast beam segments 112 of the multiple second pipe sections 2 are connected through the second tension steel strand 42.

[0043] The underground space large-section parallel pipe jacking structure adopts a structural design of multiple first pipe sections 1, multiple second pipe sections 2, and multiple frame columns 3. Multiple first pipe sections 1 are connected longitudinally to form a first longitudinal channel 10, and multiple second pipe sections 2 are connected longitudinally to form a second longitudinal channel 20. The first pipe sections 1 and the second pipe sections 2 are arranged side by side. The parallel jacking of the two pipe sections reduces the impact of ground disturbance and improves construction efficiency. After the jacking construction, the inner pipe segments 14 of the first pipe section 1 and the inner pipe segments 14 of the second pipe section can be removed, so that the first longitudinal channel 10 and the second longitudinal channel 20 are connected to form a large-section overall space.

[0044] In this structure, multiple frame columns 3 are arranged longitudinally and spaced apart within the first pipe section 1 and the second pipe section 2. The portion of the top pipe segment 11 corresponding to the frame column 3 forms a precast top beam segment 111. A post-cast top beam segment 112 is provided between the precast top beam segment 111 and the upper end of the frame column 3. The precast top beam segment 111 and the post-cast top beam segment 112 together form a top composite beam 15. The post-cast top beam segment 112 connects the top pipe segments 11 of the multiple first pipe sections 1 and the multiple top pipe segments 2 into a longitudinally continuous load-bearing structure, ensuring good reliability of the connection between the top composite beam 15 and the top pipe segments 11. Compared to existing structures where the top beam is connected to the top of both jacking pipes, this jacking pipe structure reliably connects the multiple first pipe sections 1 and the multiple second pipe sections 2 through the internal top composite beam 15. The precast top beam segment 111, as part of the top pipe segment 11, avoids the downward protrusion of the longitudinal beam occupying the internal space of the pipe section, thus creating a flat-topped large space and improving the clearance of the underground structure.

[0045] In addition, a first tension steel strand 41 is connected through the top precast beam segments 111 of multiple first pipe sections 1 and the top precast beam segments 111 of multiple second pipe sections 2, and a second tension steel strand 42 is connected through the top post-cast beam segments 112 of multiple first pipe sections 1 and the top post-cast beam segments 112 of multiple second pipe sections 2. Prestressing is applied to the top precast beam segments 111 of multiple pipe sections through the first tension steel strand 41, and prestressing is applied to the top post-cast beam segments 112 of multiple pipe sections through the second tension steel strand 42. This improves the longitudinal integrity of the jacking pipe structure. The prestressed structure has a strong load-bearing capacity and can reduce reinforcement while meeting the load-bearing capacity requirements during stress system transformation.

[0046] In this embodiment, the portion of the bottom segment 13 corresponding to the frame column 3 forms a bottom precast beam segment 131. A bottom post-cast beam segment 132 is provided between the bottom precast beam segment 131 and the lower end of the frame column 3. The bottom precast beam segment 131 and the bottom post-cast beam segment 132 form a bottom composite beam 16. A first tension steel strand 41 is connected through the bottom precast beam segments 131 of the multiple first pipe sections 1 and the bottom precast beam segments 131 of the multiple second pipe sections 2. A second tension steel strand 42 is connected through the bottom post-cast beam segments 132 of the multiple first pipe sections 1 and the bottom post-cast beam segments 132 of the multiple second pipe sections 2.

[0047] Similarly, the bottom segments 13 of multiple first pipe sections 1 and the top segments 11 of multiple second pipe sections 2 are connected by the bottom post-cast beam segment 132 to form a longitudinally continuous load-bearing structure, and the connection between the bottom composite beam 16 and the bottom segments 13 has good reliability. Prestress is applied to the bottom precast beam segment 131 of multiple pipe sections by the first tensioning steel strand 41, and prestress is applied to the bottom post-cast beam segment 132 of multiple pipe sections by the second tensioning steel strand 42, which improves the longitudinal integrity of the jacking structure. The prestressed structure has strong load-bearing capacity and can reduce reinforcement while meeting the load-bearing capacity requirements when the stress system is transformed.

[0048] Specifically, the first tensioning steel strand 41 is a negative moment prestressed steel strand, with its longitudinal middle section arched outwards; the second tensioning steel strand 42 is a positive moment prestressed steel strand, extending horizontally along the longitudinal direction. The negative moment steel strand generates a continuous longitudinal anti-arching effect in the pipe jacking structure, while the positive moment steel strand constructs a horizontal prestressing field. Together, they form a three-prestressed equilibrium system. The negative moment steel strand enhances the shear resistance of the pipe section, while the positive moment steel strand strengthens the mid-span bending resistance. This dual prestressing system significantly increases the concrete pressure reserve, ensuring an effective extension of the structure's design life.

[0049] like Figure 3 As shown, multiple first tensioning steel strands 41 and multiple second tensioning steel strands 42 are spaced apart longitudinally, with the first tensioning steel strands 41 and 42 partially overlapping. This longitudinal overlap of the two types of steel strands effectively improves the longitudinal continuity of the entire pipe jacking structure. At least two first tensioning steel strands 41 are arranged side-by-side in the top precast beam segment 111 and the bottom precast beam segment 131, and at least two second tensioning steel strands 42 are arranged side-by-side in the top post-cast beam segment 112 and the bottom post-cast beam segment 132, with the number of first tensioning steel strands 41 exceeding the number of second tensioning steel strands 42. At least two first tensioning steel strands 41 and at least two second tensioning steel strands 42 can generate balanced and reliable prestress among multiple pipe sections.

[0050] In this embodiment, the top composite beam 15 is a T-shaped composite beam, and the top post-cast beam segment 112 is located at the lower middle of the top precast beam segment 111, with the lower side of the top precast beam segment 111 flush with the lower surface of the top segment 11. Furthermore, the bottom composite beam 16 is an L-shaped composite beam, and the bottom post-cast beam segment 132 is located at the upper end of the bottom precast beam segment 131, with the upper side of the bottom precast beam segment 131 flush with the upper surface of the bottom segment 13. The T-shaped and L-shaped composite beams provide a larger bearing area, which can improve the load-bearing capacity of the top composite beam 15 and the bottom composite beam 16, while avoiding the top precast beam segment 111 and the bottom precast beam segment 131 occupying the internal space of the pipe section, ensuring that the clearance of the underground structure meets the requirements.

[0051] In addition, corrugated pipes 40 are pre-embedded inside the top precast beam segment 111, the bottom precast beam segment 131, the top post-cast beam segment 112, and the bottom post-cast beam segment 132. The first tensioning steel strand 41 and the second tensioning steel strand 42 are respectively installed through the corrugated pipes 40. The lateral distance between the frame column 3 and the outer tube segment 12 is D1, and the lateral distance between the frame column 3 and the inner tube segment 14 is D2, satisfying D2≤D1≤3*D2; a temporary steel column 5 is detachably installed between the top tube segment 11 and the bottom tube segment 13. The frame column 3 is located in the tube segment and is closer to the inner tube segment 14, which reduces the lateral cantilever length of the top tube segment 11. The two frame columns 3 play a balanced supporting role in the large cross-sectional space, ensuring the load-bearing reliability of the entire jacking structure.

[0052] The construction method for the above-mentioned large-section parallel pipe jacking structure in underground space includes the following steps:

[0053] S1. When prefabricating the segments, corrugated pipes 40 are pre-embedded in the top segment 11 and the bottom segment 13 respectively.

[0054] S2. Before jacking, assemble the first pipe section 1 and the second pipe section 2, and install temporary steel columns 5 inside the first pipe section 1 and the second pipe section 2, such as... Figure 1 As shown, the temporary steel column 5 plays a role in strengthening the support inside the pipe section.

[0055] S3. The first pipe section 1 and the second pipe section 2 are jacked up using a dual-tunnel parallel method.

[0056] S4. After the jacking is completed, the first tension steel strand 41 is connected through the corrugated pipe 40 of the top segment 11 and the bottom segment 13, negative bending moment prestress is applied to the first tension steel strand 41, it is anchored and grouted within 24 hours.

[0057] S5. Remove the temporary steel columns 5 and inner segments 14 inside the first pipe section 1 and the second pipe section 2.

[0058] S6. Tie the reinforcing bars of the top post-cast beam segment 112 and the bottom post-cast beam segment 132, and pre-embed the corrugated pipe 40, the second tension steel strand 42 and the fixed end anchor 43.

[0059] S7. Pour concrete for the top post-cast beam segment 112 and the bottom post-cast beam segment 132. After the concrete strength, elastic modulus and age meet the standards, apply positive bending moment prestress to the second tensioned steel strand 42, anchor it and grout it within 24 hours.

[0060] S8. Perform post-casting and anchoring treatment on the tensioning slots of the top post-cast beam segment 112 and the bottom post-cast beam segment 132.

[0061] The specific embodiments of the construction method for the large-section parallel pipe jacking structure in underground space of the present invention are the same as the specific embodiments of the construction method for the large-section parallel pipe jacking structure in underground space of the present invention, and will not be repeated here.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A parallel pipe jacking structure with a large cross-section in underground space, characterized in that, It includes multiple first pipe sections, multiple second pipe sections, and multiple frame columns. The multiple first pipe sections are connected in sequence along the longitudinal direction to form a first longitudinal channel, and the multiple second pipe sections are connected in sequence along the longitudinal direction to form a second longitudinal channel. The first pipe section and the second pipe section have the same structure and are arranged side by side. The first pipe section includes a top pipe segment, an outer pipe segment, a bottom pipe segment and an inner pipe segment connected in sequence in the circumferential direction. The inner pipe segment is detachably connected to the top pipe segment and the bottom pipe segment respectively. Multiple frame columns are arranged in the first pipe section and the second pipe section and are distributed at intervals along the longitudinal direction. The top pipe segment corresponding to the frame column forms a top precast beam segment. A top post-cast beam segment is provided between the top precast beam segment and the upper end of the frame column. The top precast beam segment and the top post-cast beam segment form a top composite beam. A first tension steel strand is connected through the top precast beam segments of the plurality of first pipe sections and the top precast beam segments of the plurality of second pipe sections. A second tension steel strand is connected through the top post-cast beam segments of the plurality of first pipe sections and the top post-cast beam segments of the plurality of second pipe sections.

2. The underground space large-section parallel pipe jacking structure according to claim 1, characterized in that, The bottom segment corresponding to the frame column forms a bottom precast beam segment, and a bottom post-cast beam segment is provided between the bottom precast beam segment and the lower end of the frame column. The bottom precast beam segment and the bottom post-cast beam segment form a bottom composite beam. A first tension steel strand is connected through the bottom precast beam segments of the plurality of first pipe sections and the bottom precast beam segments of the plurality of second pipe sections. A second tension steel strand is connected through the bottom post-cast beam segments of the plurality of first pipe sections and the bottom post-cast beam segments of the plurality of second pipe sections.

3. The underground space large-section parallel pipe jacking structure according to claim 2, characterized in that, The first tensioned steel strand is a negative moment prestressed steel strand, and the longitudinal middle part of the first tensioned steel strand is arched outward; the second tensioned steel strand is a positive moment prestressed steel strand, and the second tensioned steel strand is extended horizontally along the longitudinal direction.

4. The underground space large-section parallel pipe jacking structure according to claim 3, characterized in that, Multiple first tensioning steel strands are arranged at intervals along the longitudinal direction, and multiple second tensioning steel strands are arranged at intervals along the longitudinal direction, with the first tensioning steel strands and the second tensioning steel strands partially overlapping.

5. The underground space large-section parallel pipe jacking structure according to claim 3, characterized in that, At least two first tensioning steel strands are arranged side by side in the top precast beam segment and the bottom precast beam segment, and at least two second tensioning steel strands are arranged side by side in the top post-cast beam segment and the bottom post-cast beam segment, and the number of first tensioning steel strands is greater than the number of second tensioning steel strands.

6. The underground space large-section parallel pipe jacking structure according to claim 3, characterized in that, The top composite beam is a T-shaped composite beam, and the top post-cast beam segment is located in the lower middle part of the top precast beam segment. The lower side of the top precast beam segment is flush with the lower surface of the top tube segment.

7. The underground space large-section parallel pipe jacking structure according to claim 3, characterized in that, The bottom composite beam is an L-shaped composite beam, and the bottom post-cast beam segment is located at the upper end of the bottom precast beam segment. The upper side of the bottom precast beam segment is flush with the upper surface of the bottom tube segment.

8. The underground space large-section parallel pipe jacking structure according to claim 3, characterized in that, Corrugated pipes are pre-embedded inside the top precast beam segment, the bottom precast beam segment, the top post-cast beam segment, and the bottom post-cast beam segment, respectively, and the first tensioning steel strand and the second tensioning steel strand are respectively installed through the corrugated pipes.

9. The underground space large-section parallel pipe jacking structure according to claim 1, characterized in that, The lateral distance between the frame column and the outer tube segment is D1, and the lateral distance between the frame column and the inner tube segment is D2, satisfying D2≤D1≤3*D2; a temporary steel column can be detachably installed between the top tube segment and the bottom tube segment.

10. A construction method for a large-section parallel pipe jacking structure in underground space as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. When prefabricating tunnel segments, corrugated pipes are pre-embedded in the top and bottom tunnel segments respectively; S2. Before jacking, the first and second pipe sections are spliced ​​and assembled, and temporary steel columns are installed inside the first and second pipe sections. S3. The first and second pipe sections are jacked up using a dual-tunnel parallel method. S4. After the jacking is completed, the first tension steel strand is connected through the corrugated pipes of the top and bottom segments, negative bending moment prestress is applied to the first tension steel strand, it is anchored and grouted within 24 hours. S5. Remove the temporary steel columns and inner segments inside the first and second pipe sections; S6. Tie the reinforcing bars of the top and bottom post-cast beam segments, and pre-embed the corrugated pipes, the second tension steel strands, and the fixed end anchors. S7. Pour concrete for the top and bottom post-cast beam segments. After the concrete strength, modulus of elasticity and age meet the standards, apply positive bending moment prestress to the second tensioned steel strand, anchor it and grout within 24 hours. S8. Perform post-casting anchor sealing treatment on the tensioning slots of the top and bottom post-cast beam segments.

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