A kind of high bridge large-span pile cap structure crossing subway station and its construction method

Abstract

This invention discloses a large-span pier structure for an elevated bridge spanning a subway station and its construction method. The structure includes: a horizontally arranged large-span pier beam, at least two vertically arranged pile foundations below the large-span pier beam, elevated piers vertically arranged above the large-span pier beam, an elevated bridge box girder horizontally arranged on the elevated piers, and tensioning anchor cable components. The pile foundations are evenly distributed on both sides of the large-span pier beam, with one pile foundation and the corresponding elevated pier on one side coaxially arranged. The coaxial elevated pier and pile foundation are connected by rigid connectors. Multiple sets of tensioning anchor cable components are arranged inside the large-span pier beam, spaced apart along the longitudinal direction of the large-span pier beam. The tensioning anchor cable components improve the bending resistance of the large-span pier beam. This invention comprehensively considers the loads borne in both the horizontal and longitudinal directions, ensuring the stability and reliability of the large-span pier structure, and can be widely used when bridges span existing underground structures.

Description

Technical Field

[0001] This invention relates to the field of bridge structure design technology, and in particular to a long-span pier structure for an elevated bridge spanning a subway station and its construction method. Background Technology

[0002] As an indispensable public transportation tool for people's daily work and life, the subway has become one of the important ways to alleviate urban traffic pressure. The subway not only provides great convenience for people's travel, but also plays a fundamental role in promoting urban construction and planning. Due to urban space constraints and overall urban layout, subway stations are usually planned in parallel with elevated highways.

[0003] Currently, the main method for combining subway stations with viaducts is to use prestressed pier beams connected to cap beams and column piers to span the subway station structure laterally. Because subways are slender structures, a standard two-level underground island platform station typically has a total width exceeding 18.5m, resulting in a large span for the prestressed pier beams.

[0004] In existing technologies, the elevated piers are located in the middle of the prestressed abutment beams. Loads in both the transverse and longitudinal directions are directly applied to the prestressed abutment beams, making them more susceptible to damage than pile foundations. Because the load-bearing characteristics and mechanical transmission performance of the relevant structures in the two main transverse and longitudinal directions are not comprehensively considered, the middle of the prestressed abutment beam is prone to downward bending under compression, and the ends of the prestressed abutment beam are prone to cracking under shear force. The longitudinal load will directly act on the soil in the elevated bridge construction area. If there are existing structures in this area (such as subway stations, gas pipelines, communication optical cables, etc.), these structures will be at risk of compressive failure. Therefore, it is impossible to protect existing building structures within the construction area. Summary of the Invention

[0005] This invention provides a large-span pier structure for an elevated bridge spanning a subway station and its construction method, in order to overcome the problem of uneven lateral and longitudinal load-bearing in the original large-span pier structure for elevated bridges.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A viaduct with a large span pier structure spanning a subway station is characterized by comprising: a horizontally arranged large span pier beam, at least two vertically arranged pile foundations below the large span pier beam, a viaduct pier vertically arranged above the large span pier beam, a viaduct box girder horizontally arranged on the viaduct pier, and tension anchor cable components. The pile foundations are evenly distributed on both sides of the large span pier beam, with the pile foundations on one side and the corresponding viaduct pier coaxially arranged. The coaxial viaduct pier and pile foundations are connected by rigid connectors. Multiple sets of tension anchor cable components are arranged inside the large span pier beam, and these multiple sets of tension anchor cable components are spaced apart along the longitudinal direction of the large span pier beam. The tension anchor cable components can improve the bending resistance of the large span pier beam.

[0008] Furthermore, the tensioning anchor cable component includes a pre-embedded pipe arranged in the transverse direction of the large-span pier beam, an anchor cable bundle passing through the pre-embedded pipe, and tensioning end anchors and fixed end anchors respectively set at both ends of the anchor cable bundle. One end of the anchor cable bundle passes through the tensioning end anchor, and the other end is fixedly connected to the fixed end anchor. The pre-embedded pipe is set as a straight line and / or a curved line.

[0009] Furthermore, the large-span pier beam is equipped with three sets of tension anchor cable components. The top set is the first set of tension anchor cable components, the bottom set is the third set of tension anchor cable components, and the set between the first and third sets of tension anchor cable components is the second set of tension anchor cable components. The embedded pipes of the first and second sets of tension anchor cable components are set as curved sections, which consist of three horizontal straight sections and two inclined transition sections. The middle horizontal straight section is lower than the horizontal straight sections at both ends. The embedded pipes of the third set of tension anchor cable components are set as straight sections.

[0010] Furthermore, a deformation buffer component is installed between the large-span pier beam and the subway station, which can provide deformation space for the large-span pier beam.

[0011] The deformation buffer is preferably an arched beam, with the arch of the beam facing the large-span pier beam.

[0012] Furthermore, corner reinforcement blocks are installed at the connection between the large-span pier beam and the pile foundation. The corner reinforcement blocks contain horizontal tie bars and multiple diagonal reinforcing bars. The multiple reinforcing bars are arranged in parallel and at intervals. One end of the reinforcing bar is fixedly connected to the large-span pier beam, and the other end is fixedly connected to the pile foundation. One end of the tie bar is fixedly connected to the large-span pier beam, and the other end is connected to the large-span pier beam after passing through multiple reinforcing bars.

[0013] Furthermore, a waterproof structure is provided on the outer periphery of the pile foundation, which is formed by a two-liquid grouting method.

[0014] Furthermore, the bottom of the pile foundation is equipped with enlarged-base piles, which can increase the vertical bearing capacity and pull-out resistance of the pile foundation.

[0015] Furthermore, the top of the pile foundation is provided with a lower groove, and one end of the rigid connector is inserted into the lower groove for fixed connection.

[0016] Furthermore, vibration damping grooves are installed between the subway station and the pile foundation, which can reduce the disturbance to the subway station during construction.

[0017] Furthermore, a steel pipe column is installed at the center of the elevated pier, and the top of the steel pipe column is fixedly connected to the box girder of the elevated bridge.

[0018] Furthermore, the rigid connector preferably includes a steel casting and a lower rib. One end of the steel casting has an upper groove, and the other end is fixedly connected to the lower rib. The steel casting is placed between the pile foundation and the elevated pier column, and the lower rib is fixed to the lower groove at the top of the pile foundation.

[0019] Furthermore, the elevated piers include a first group of elevated piers coaxially arranged with the pile foundation on one side and a second group of elevated piers arranged at any point on the large-span pier beam; the elevated bridge box girder is horizontally arranged on the first group of elevated piers and the second group of elevated piers.

[0020] Furthermore, a first steel pipe column is installed at the center of the first group of elevated piers, with one end of the first steel pipe column fixedly connected to a rigid connector and the other end flush with the top of the first group of elevated piers; a second steel pipe column is installed at the center of the second group of elevated piers, with one end of the second steel pipe column fixed inside the large-span pier beam and the other end flush with the top of the second group of elevated piers.

[0021] A construction method for a long-span pier structure of an elevated bridge spanning a subway station includes the following steps:

[0022] Step (1), construct the pile foundation:

[0023] First, drill pile holes on both sides of the existing subway station that meet the outer diameter of the pile foundation, and maintain the stability of the pile holes by using mud slurry to protect the walls; then, vertically place the steel cage into the pile hole, pour concrete into the steel cage, and obtain the pile foundation after the concrete reaches the design strength; use the pre-supported formwork method to leave a lower groove on the top of the pile foundation, and insert the lower end of the rigid connector into the lower groove.

[0024] Step (two), construct the large-span pier beam:

[0025] The steel reinforcement cage required for the construction of the large-span pier beam is tied above the pile foundation. The tensioning anchor cable components and the large-span pier beam are cast as a whole. A through hole is reserved at the end of the large-span pier beam for the rigid connector to pass through. The upper end of the rigid connector passes through the through hole and extends upward. Concrete is poured into the through hole and the lower groove. After the concrete reaches the required strength, a stable connection is achieved between the rigid connector, the pile foundation and the large-span pier beam.

[0026] Step (3), construct the elevated piers:

[0027] On the large-span pier beam, the steel reinforcement cage required for the elevated pier column is tied and constructed, and concrete is poured into the steel reinforcement cage until the design strength is reached to form the elevated pier column.

[0028] Step (four), install the viaduct box girder:

[0029] The viaduct box girders are selected from precast components. The viaduct box girders are hoisted onto the viaduct piers and inspected and confirmed after installation.

[0030] Furthermore, in step (ii), there are at least three sets of tensioning anchor cable components. After the large-span pier beam is formed, two sets of tensioning anchor cable components are tensioned, with one set having a control stress of 1395MPa and the other set having a control stress of 1310MPa.

[0031] In step (iv), after installation, the remaining tension anchor cable components are tensioned, and the controlled stress is 1310 MPa.

[0032] Furthermore, before step (1), vibration damping trenches are first manually excavated on both sides of the existing subway station.

[0033] Furthermore, in step (i), before pouring concrete into the reinforcing cage, a grouting pipe is lowered between the reinforcing cage and the pile hole. The tail end of the grouting pipe is lowered to the bottom of the pile hole, while the head end remains outside the pile hole. Grout is injected into the bottom of the pile hole through the grouting pipe. After solidification and strength formation, an enlarged-base pile is formed.

[0034] Furthermore, in step (i), while pouring concrete into the reinforcing cage, a two-component grouting process is performed between the pile hole and the reinforcing cage to form a waterproof structure.

[0035] Furthermore, in step (i), while pouring concrete into the steel cage, the corner reinforcement block is constructed using the pre-supported formwork method to ensure that the lower joint of the reinforcing bar of the corner reinforcement block is inserted into the pile foundation, and the tie bar and reinforcing bar are poured into the corner reinforcement block.

[0036] Furthermore, in step (a), after inserting the lower end of the rigid connector into the lower groove, the construction area is excavated manually, the deformation buffer component is installed, and then the soil is backfilled.

[0037] Furthermore, in step (i), after inserting the lower end of the rigid connector into the lower groove, the construction area is excavated manually, the steel arch frame is tied, the space under the arch of the steel arch frame is partitioned with pre-placed gypsum board, and then concrete is poured into the steel arch frame. After the concrete reaches its strength, an arch beam is formed, and the soil is backfilled.

[0038] Furthermore, in step (iii), while binding the steel reinforcement cage required for the construction of the elevated pier, a steel pipe column is set at the center line of the elevated pier, so that one end of the steel pipe column is fixedly connected to the rigid connector and the other end is flush with the top of the elevated pier.

[0039] Beneficial effects:

[0040] First, this application incorporates multiple sets of tensioned anchor cable components within the large-span pier cap beam. By using prestressed tension to offset the load, it improves the bending moment resistance of the large-span pier cap beam. It fully utilizes the prestressed tension of the multiple sets of anchor cable components and the tensile and compressive strength characteristics of the reinforced concrete beam, thereby enhancing the lateral bearing capacity of the large-span pier cap structure and reducing the lateral load borne by the pile foundation. Furthermore, rigid connectors are installed between the elevated piers and the pile foundation, forming a longitudinal structure that directly transmits the load, fully leveraging the excellent bearing capacity of the elevated piers and pile foundation, and reducing the longitudinal load borne by the large-span pier cap beam. The bottom piles compact the soil near the pile foundation, increase the bearing area, and enhance the end bearing capacity of the pile foundation. This increases the vertical bearing capacity and pull-out resistance of the pile foundation, and allows the bearing capacity characteristics of the underlying rock strata to be utilized. The overall structure's lateral and longitudinal bearing capacity is comprehensively considered, and the mechanical properties of the beams and columns are fully combined. This ensures that the large-span pier beams and pile foundations can fully utilize their bearing capacity when supporting the viaduct, avoiding the large-span pier beams bearing all longitudinal loads. Therefore, this solves the problem of unbalanced lateral and longitudinal bearing capacity of the large-span pier structure of the viaduct built above the existing subway station area.

[0041] Secondly, this application adopts a method of integrally casting the tensioned anchor cable component and the large-span pier beam, and then inserting the rigid connector through the pre-reserved through hole at the end of the large-span pier beam into the groove at the bottom of the pile foundation. Concrete is poured between the through hole and the groove at the bottom. After the concrete reaches the required strength, a stable connection is achieved between the tensioned anchor cable component, the rigid connector, the pile foundation, and the large-span pier beam. Then, the steel reinforcement cage required for the elevated pier is tied and constructed, and concrete is poured into the steel reinforcement cage until the design strength is reached to form the elevated pier. Therefore, the construction problem of the connection between the elevated pier, the rigid connector, the pile foundation, the tensioned anchor cable component, and the large-span pier beam is solved. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of a large-span pier structure for an elevated bridge spanning a subway station, according to Embodiment 1 of the present invention.

[0044] Figure 2 This is a schematic elevation section of the tension anchor cable component structure in Embodiment 1 of the present invention. Figure 1 ;

[0045] Figure 3 for Figure 2 Sectional view of section I-I;

[0046] Figure 4 This is a schematic elevation section of the tension anchor cable component structure in Embodiment 1 of the present invention. Figure 2 ;

[0047] Figure 5 for Figure 4 Sectional view of section II-II;

[0048] Figure 6 This is a schematic elevation section of the tension anchor cable component structure in Embodiment 1 of the present invention. Figure 3 ;

[0049] Figure 7 for Figure 6 Sectional view of section III-III;

[0050] Figure 8 This is a schematic diagram of the connection structure of the elevated piers, rigid connectors, and pile foundations.

[0051] Figure 9 Structural diagram of the corner reinforcement block;

[0052] Figure 10 This is a top view of the pile foundation;

[0053] Figure 11 This is a schematic diagram of the vibration damping groove structure.

[0054] 1. Large-span pier beams;

[0055] 2. Pile foundation; 21. Waterproof structure; 22. Expanded base pile; 23. Lower groove;

[0056] 3. Elevated piers; 31. First group of elevated piers; 32. Second group of elevated piers; 33. Steel pipe columns; 331. First steel pipe column; 332. Second steel pipe column; 3311. Supporting steel pipe; 3312. Upper reinforcing bars;

[0057] 4. Tensioning anchor cable components; 41. T1 group tensioning anchor cable components; 42. T2 group tensioning anchor cable components; 43. T3 group tensioning anchor cable components; 411. Anchor cable bundle; 412. Embedded pipe; 4121. Plastic corrugated pipe; 413. Fixing ring; 414. Tensioning end anchor; 415. Fixed end anchor;

[0058] 5. Rigid connector; 51. Steel casting; 52. Lower rib; 53. Upper groove;

[0059] 6. Elevated bridge box girder;

[0060] 7. Deformation buffer components; 71. Arched beams;

[0061] 8. Corner reinforcement block; 81. Tie rod; 811. Left bend section; 812. Right bend section; 82. Reinforcing rib; 821. Upper bend section; 822. Lower bend section;

[0062] 9. Vibration damping groove;

[0063] 10. Subway station. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] Example 1

[0066] Reference Figure 1 A viaduct with a large span pier structure spanning a subway station includes: multiple vertically arranged pile foundations 2, a large span pier beam 1 horizontally arranged on the upper end of the pile foundations, multiple viaduct piers 3 vertically arranged above the large span pier beams, and a viaduct box girder 6 horizontally arranged on the viaduct piers 3; the multiple pile foundations 2 are divided into two rows, and the two rows of pile foundations 2 are distributed on both sides of the length direction of the large span pier beam 1. The multiple pile foundations 2 in the same row are equally spaced along the width direction of the large span pier beam 1, and the two rows of pile foundations 2 and the large span pier beam 1 enclose a space that can accommodate the subway station.

[0067] Multiple elevated piers 3 are divided into two rows, namely the first group of elevated piers 31 and the second group of elevated piers 32. The two rows of elevated piers 3 are located on both sides of the length of the elevated bridge box girder 6, and the multiple elevated piers 3 in the same row are equally spaced along the width of the elevated bridge box girder 6. The first group of elevated piers 31 is located at the edge above the large-span pier cap beam 1. The first group of elevated piers 31 is coaxial with the pile foundation 2 on the corresponding side to avoid the first group of elevated piers 31 generating bending moment on the large-span pier cap beam 1. The second group of elevated piers 32 is located in the middle above the large-span pier cap beam 1, with the elevated bridge box girder 6 fixed at the top. The elevated bridge box girder 6, the large-span pier cap beam 1, the first group of elevated piers 31, and the second group of elevated piers 32 enclose a space that can accommodate a ground-level road. The viaduct box girder 6 is set on top of the viaduct pier 3. The center of gravity of the viaduct box girder 6 falls between the first group of viaduct piers 31 and the second group of viaduct piers 32. The two groups of viaduct piers 3 have stronger load-bearing capacity and good stability.

[0068] Combination Figure 1 and Figure 2 The large-span pier beam 1 is equipped with a tensioning anchor cable component 4. The tensioning anchor cable component 4 includes multiple fixing rings 413 fixed inside the large-span pier beam 1, a pre-embedded pipe 412 fixed inside the large-span pier beam 1, an anchor cable bundle 411 passing through the pre-embedded pipe 412, a tensioning end anchor 414, and a fixed end anchor 415. The tensioning end anchor 414 is located at the left end of the large-span pier beam 1, and the fixed end anchor 415 is located at the right end of the large-span pier beam 1.

[0069] Multiple fixing rings 413 are arranged at intervals along the transverse direction of the large-span pier beam 1. The pre-embedded pipe 412 is preferably a plastic corrugated pipe 4121. One end of the plastic corrugated pipe 4121 is fixedly connected to the fixed end anchor 415, and the other end passes through the fixing ring 413 in sequence and is fixedly connected to the tensioning end anchor 414. Utilizing the flexible characteristics of the plastic corrugated pipe 4121, it is beneficial to pass through the fixing ring 413 to form a straight or curved plastic corrugated pipe 4121.

[0070] One end of the anchor cable bundle 411 is fixedly connected to the fixed end anchor 415, and the other end passes through the plastic corrugated pipe 4121 and the tensioning end anchor 414. The shape of the anchor cable bundle 411 is consistent with the plastic corrugated pipe 4121 through which it passes. When a force is applied to the anchor cable bundle 411, one end of the anchor cable bundle 411 is fixed in place by the fixed end anchor 415, and the other end of the anchor cable bundle 411 moves slowly to the left from the tensioning end anchor 414. When the force is removed, the tensioning end anchor 414 locks the anchor cable bundle 411, thereby adjusting the tension control stress of the anchor cable bundle 411.

[0071] The tension anchor cable component 4 is configured in multiple groups. This application does not limit the number of groups of tension anchor cable components 4. This embodiment uses three groups of tension anchor cable components 4 as an example. The three groups of tension anchor cable components 4 are spaced apart along the longitudinal direction of the large-span pier beam 1. The uppermost group of tension anchor cable components 4 is designated as group T1 tension anchor cable component 41, the middle group as group T2 tension anchor cable component 42, and the lowermost group as group T3 tension anchor cable component 43. The plastic corrugated pipe 4121 of the T1 and T2 groups of tension anchor cable components is curved, while the plastic corrugated pipe 4121 of the T3 group of tension anchor cable components 43 is straight. The curved anchor cable bundle 411 has a positive bending moment at its mid-span section, while the straight anchor cable bundle 411 generates the same amount of prestress at every section of the beam. The tensioning prestress counteracts the load. The straight and curved anchor cable bundles 411 are tensioned in batches, and the tension force of the anchor cable bundles 411 in the T1 group is controlled to be greater than that in the T2 and T3 groups, thus compensating for the prestress loss caused by the elastic compression of concrete in the later batches. Therefore, the tensioning anchor cable component 4 can improve the bending performance of the large-span pier beam 1.

[0072] The upper left corner of the large-span pier beam 1 is set as the origin of the coordinate system. The horizontal direction to the right is the positive direction of the horizontal coordinate, and the vertical direction downward is the positive direction of the vertical coordinate. The specific positions of the projections formed by the anchor bundles 411 corresponding to the three sets of tension anchor components 4 on the vertical section of the large-span pier beam 1 are shown in Table 1, the table of prestressed anchor bundle vertical section curve elements.

[0073] Table 1. Element Table of Elevation Section Curve of Prestressed Anchor Cable Bundle

[0074]

[0075] Combination Figure 2 and Figure 3 The upper left corner of section I-I of the large-span pier beam 1 is set as the origin of the coordinate system. The horizontal direction to the right is the positive direction of the horizontal coordinate, and the vertical direction downward is the positive direction of the vertical coordinate. The vertical coordinates of the projections of the anchor bundles 411 corresponding to the three sets of tension anchor components 4 on the section are shown in Table 2, the table of vertical coordinate elements of the prestressed anchor bundle I-I section.

[0076] Table 2. Longitudinal coordinate elements of prestressed anchor cable bundle I-I section.

[0077]

[0078] Each group of tensioned anchor cable components 4 is equipped with 22 anchor cable bundles 411, which are arranged at intervals of 45cm. The abscissa of the projection of the first anchor cable bundle 411 in each group on section I-I is 52.5cm, and the abscissa of the projection of the 22nd anchor cable bundle 411 in each group on section I-I is 997.5cm.

[0079] Combination Figure 4 and Figure 5 The upper left corner of the II-II section of the large-span pier beam 1 is set as the origin of the coordinate system. The horizontal direction to the right is the positive direction of the horizontal coordinate, and the vertical direction downward is the positive direction of the vertical coordinate. The vertical coordinates of the projections of the anchor bundles 411 corresponding to the three sets of tension anchor components 4 on the section are shown in Table 3, the table of vertical coordinate elements of the prestressed anchor bundle II-II section.

[0080] Table 3. Longitudinal coordinate elements of prestressed anchor cable bundle II-II section.

[0081]

[0082] Each group of tensioned anchor cable components 4 is equipped with 22 anchor cable bundles, with the anchor cable bundles 411 arranged at 45cm intervals. The abscissa of the projection of the first anchor cable bundle 411 in each group on the II-II section is 52.5cm, and the abscissa of the projection of the 22nd anchor cable bundle 411 in each group on the II-II section is 997.5cm.

[0083] Combination Figure 6 and Figure 7 The upper left corner of the III-III section of the large-span pier beam 1 is set as the origin of the coordinate system. The horizontal direction to the right is the positive direction of the horizontal coordinate, and the vertical direction downward is the positive direction of the vertical coordinate. The vertical coordinates of the projections of the anchor bundles 411 corresponding to the three sets of tension anchor components 4 on the section are shown in Table 4, the table of vertical coordinate elements of the prestressed anchor bundles III-III section.

[0084] Table 4. Longitudinal coordinate elements of prestressed anchor cable strands at section III-III

[0085]

[0086] Each group of tensioning anchor cable components 4 is equipped with 22 anchor cable bundles 411, which are arranged at intervals of 45cm. The abscissa of the projection of the first anchor cable bundle 411 in each group on the III-III section is 52.5cm, and the abscissa of the projection of the 22nd anchor cable bundle 411 in each group on the III-III section is 997.5cm.

[0087] The tension control stress of the inner anchor bundle 411 of the T1 group tension anchor component 41 is 1395MPa, the tension control stress of the inner anchor bundle 411 of the T2 group tension anchor component 42 is 1310MPa, and the tension control stress of the inner anchor bundle 411 of the T3 group tension anchor component 43 is 1310MPa.

[0088] Reference Figure 8 A rigid connector 5 is provided between the first set of elevated piers 31 and the coaxial pile foundation 2. The upper end of the rigid connector 5 passes through the large-span pier beam 1 and connects to the first set of elevated piers 31, while the lower end of the rigid connector 5 connects to the upper end of the pile foundation 2. The rigid connector 5 includes a cylindrical steel casting 51 and a lower reinforcing bar 52. The upper end of the steel casting 51 has a cylindrical upper groove 53, and the lower end is welded to the lower reinforcing bar 52. The steel casting 51 is simple to manufacture, has good bearing capacity, strong corrosion resistance, and can reliably connect the pile foundation 2 and the first set of elevated piers 31. The elevated pier column 31; the top of the pile foundation 2 is provided with a cylindrical lower groove 23 that is 5mm larger than the outer diameter of the rigid connector 5, which is conducive to aligning the steel casting 51 with the pile foundation 2; the lower reinforcing bar 52 is set inside the lower groove 23, and the cylindrical steel casting 51 is coaxial with the pile foundation 2 through the lower reinforcing bar 52. Cement is poured into the lower groove 23 to fix the steel casting 51 and the pile foundation 2. The lower reinforcing bar 52 can increase the stress area between the steel casting 51 and the pile foundation 2, reduce the pressure on the end face of the pile foundation 2, and make the connection more reliable.

[0089] In a specific embodiment, refer to Figure 1 The preferred embodiment of the deformation buffer component 7 is:

[0090] A deformation buffer component 7 is installed between the large-span pier beam 1 and the subway station. The deformation buffer component 7 is preferably an arched beam 71, which is constructed within the soil between the large-span pier beam 1 and the subway station facilities. The arched beam 71 is an arch with straight ends and an upward convex middle section, and is located directly below the second set of elevated pier columns 32. When the large-span pier beam 1 bends and deforms downwards, the deformation first acts on the lower arched beam 71. The arched cavity of the arched beam 71 provides deformation space, preventing direct impact on the soil above the subway station and thus protecting the subway station.

[0091] In a specific embodiment, refer to Figure 9 The preferred solution for corner reinforcement block 8 is:

[0092] A corner reinforcement block 8 is provided at the connection between the large-span pier beam 1 and the pile foundation 2. The cross-section of the corner reinforcement block 8 is a figure enclosed by two right-angled sides, an upwardly protruding arc, and a small straight line segment connecting the straight line and the arc. The corner reinforcement block 8 contains a horizontal tie bar 81 and multiple oblique reinforcing bars 82, with the reinforcing bars 82 intersecting at the two right-angled sides. This application does not limit the number of tie bars 81 and reinforcing bars 82; this embodiment uses one tie bar 81 and four reinforcing bars 82 as an example.

[0093] The reinforcing bars 82 are arranged at a 45° angle, with four reinforcing bars 82 arranged in parallel and at intervals. The upper bent section 821 of the reinforcing bars 82 is fixedly connected to the large-span pier beam 1, and the lower bent section 822 is fixedly connected to the pile foundation 2. After prestressing, the distance between the large-span pier beam 1 and the pile foundation 2 increases along the direction of the reinforcing bars 82, causing the reinforcing bars 82 to be under tension. Taking advantage of the fact that the tensile stress of steel bars is better than that of concrete, corner reinforcement blocks 8 of steel-concrete structure are used to reinforce the connection between the large-span pier beam 1 and the pile foundation 2.

[0094] The left-bending section 811 of the tie bar 81 is fixedly connected to the large-span pier beam 1; the horizontal section is connected to the pile foundation 2 after being reinforced with four reinforcing bars 82; and the right-bending section 812 extends from the pile foundation 2 and connects to the large-span pier beam 1. After prestressing tensioning, the bottom of the large-span pier beam 1 is subjected to a positive bending moment and is under compression, causing the tie bar 81 to be under compression. Utilizing the superior compressive strength of steel bars compared to concrete, the tie bar resists the prestress generated near the connection between the large-span pier beam 1 and the pile foundation 2, thus reinforcing the connection between the large-span pier beam 1 and the pile foundation 2.

[0095] In a specific embodiment, combined with Figure 1 and Figure 10 The preferred scheme for pile foundation 2 is:

[0096] A waterproof structure 21 is provided on the outer periphery of the pile foundation 2. The waterproof structure 21 is formed by a double-liquid grouting method. The waterproof structure 21 can prevent the pile foundation 2 from being eroded by groundwater and ensure the reliability of the pile foundation 2.

[0097] In a specific embodiment, combined with Figure 1 and Figure 8 The preferred scheme for pile foundation 2 is:

[0098] The bottom of the pile foundation 2 is provided with an enlarged-base pile 22. The top view projection of the pile foundation 2 is located in the center of the top view projection of the enlarged-base pile 22. The ratio of the diameter of the enlarged-base pile 22 to the diameter of the pile foundation 2 is 2.5. The setting of the enlarged-base pile 22 can increase the vertical bearing capacity and pull-out force of the pile foundation 2.

[0099] In a specific embodiment, combined with Figure 1 and Figure 11 The preferred design for the damping groove 9 is:

[0100] A vibration damping groove 9 is provided between the subway station and the pile foundation 2. The vibration damping groove 9 is a rectangular cavity with an open upper surface. The length of the vibration damping groove 9 is greater than the length of the construction area of ​​the pile foundation 2. A gap is reserved between the vibration damping groove 9 and the pile foundation 2, which is preferably 3m. The vibration damping groove 9 can reduce the disturbance to the subway station during construction.

[0101] In a specific embodiment, combined with Figure 1 and Figure 8 The preferred solution for elevated pier 3 is:

[0102] A steel pipe column 33 is installed at the center of the elevated pier 3, and the top of the steel pipe column 33 is fixedly connected to the box girder 6 of the elevated bridge.

[0103] At the center of the first group of elevated piers 31, a first steel pipe column 331 is installed. The lower end of the first steel pipe column 331 is inserted into the cylindrical upper groove 53 at the top of the rigid connector 5. Concrete is poured into the upper groove 53 to fix the first steel pipe column 331 to the rigid connector 5. The first steel pipe column 331 includes a supporting steel pipe 3311 and an upper rib 3312. The lower end of the supporting steel pipe 3311 is welded to the upper rib 3312. The supporting steel pipe 3311 utilizes the characteristic that the compressive strength of metal is greater than that of concrete to support the pier. The combination of the supporting steel pipe 3311 and the steel-concrete structure improves the longitudinal bearing capacity of the first group of elevated pier columns 31; the upper rib 3312 is set in the upper groove 53, and cement is poured into the upper groove 53 to fix the supporting steel pipe 3311 and the rigid connector 5. The supporting steel pipe 3311 and the rigid connector 5 are coaxial through the upper rib 3312. The upper rib 3312 can increase the force-bearing area between the supporting steel pipe 3311 and the rigid connector 5, reduce the pressure on the end face of the rigid connector 5, and make the connection more reliable.

[0104] At the center of the second group of elevated piers 32, a second steel pipe column 332 is provided. The second steel pipe column 332 includes a supporting steel pipe 3311 and an upper rib 3312. The lower end of the supporting steel pipe 3311 is welded to the upper rib 3312, and the upper rib 3312 is welded and fixed inside the large-span pier beam 1. The second steel pipe column 332 utilizes the characteristic that the compressive strength of metal materials is greater than that of concrete to combine the supporting steel pipe 3311 with the steel-concrete structure to improve the longitudinal bearing capacity of the second group of elevated piers 32, so that the load is directly transferred to the large-span pier beam 1.

[0105] The mechanism of the device in this application:

[0106] When the road surface of the viaduct is loaded, the box girder 6 of the viaduct bears the upper load, and the load is transmitted downward in two parts along the first group of viaduct piers 31 and the second group of viaduct piers 32.

[0107] Part of the load is transmitted downwards in two paths through the first group of elevated piers 31 and the first steel pipe column 331 inside them. One path is transmitted from the first steel pipe column 331 to the pile foundation 2 via the rigid connector 5. The pile foundation 2 then transmits the load to the underground rock layer via the expanded base pile 22. The other path is transmitted from the first elevated pier 31 to the pile foundation 2 via the large span pier beam 1. The pile foundation 2 then transmits the load to the underground rock layer via the expanded base pile 22.

[0108] Another portion of the load is transferred downwards through the second elevated pier column 32 to the large-span pier beam 1, and then from the large-span pier beam 1 downwards along the pile foundations 2 on both sides. Finally, the load is transferred to the underground rock layer through the expanded-base piles 22.

[0109] This increases the load on the longitudinal connection structure formed by the pile foundation 2, the rigid connector 5, and the first elevated pier column 31, while reducing the load on the large-span pier beam 1.

[0110] The load is transmitted downwards through the second elevated pier column 32 to the middle of the large-span pier beam 1, generating a downward negative bending moment. The three sets of tensioned anchor cable components 4 are prestressed and generate a positive bending moment in the middle of the large-span pier beam 1, which cancels out the negative bending moment. The load is then transmitted from the large-span pier beam 1 to the pile foundations 2 on both sides. The load generates a negative shear force at the connection between the large-span pier beam 1 and the pile foundation 2. The three sets of tensioned anchor cable components 4 are prestressed and generate a positive shear force at the connection between the large-span pier beam 1 and the pile foundation 2, which cancels out the negative shear force. This reduces the shear force on both ends of the large-span pier beam 1, preventing cracking at the top of the large-span pier beam 1 and damage to the pile foundation 2.

[0111] By rationally allocating the load transfer path, prestressing tensioning improves the bending moment resistance of the large-span pier beam 1, and prestressing tensioning reduces the shear force at the connection between the large-span pier beam 1 and the pile foundation 2, making full use of the mechanical properties of the large-span pier beam 1 and the pile foundation 2, so that the lateral and longitudinal loads of the large-span pier beam structure of the viaduct can be balanced.

[0112] Example 2

[0113] This embodiment provides a construction method for a long-span pier structure of an elevated bridge spanning a subway station, including the following steps:

[0114] Step (1): Excavate and install vibration damping groove 9:

[0115] Vibration damping trenches were manually excavated on both sides of the existing subway station.

[0116] Step (two), construct pile foundation 2:

[0117] In the proposed construction areas on both sides of the existing subway station, rotary drilling rigs are used to drill pile holes that meet the outer diameter size of double-liquid grouting. During the construction process, forward rotary drilling is adopted, and the stability of the pile holes is maintained by mud slurry wall protection.

[0118] Step (3), construct pile foundation 2:

[0119] One end of the prefabricated steel cage is lifted by a crane and placed vertically into the pile hole. A grouting pipe is then lowered between the steel cage and the pile hole, with the tail end of the grouting pipe lowered to the bottom of the pile hole and the head end left outside the pile hole. Grout is injected into the bottom of the pile hole through the grouting pipe. After solidification and strength formation, an enlarged-base pile 22 is formed.

[0120] Step (four), construct pile foundation 2:

[0121] A cylindrical lower groove 23 is reserved above the steel cage using the pre-supported formwork method; at the same time, the corner reinforcement block 8 is constructed using the pre-supported formwork method to ensure that the lower bent section 822 of the reinforcing bar 82 of the corner reinforcement block 8 is inserted into the steel cage, and the tie bar 81 and the reinforcing bar 82 are poured into the corner reinforcement block 8.

[0122] Step (5), construct pile foundation 2:

[0123] Concrete is poured into the reinforcing cage, and at the same time, double-liquid grouting is performed between the pile hole and the reinforcing cage. After the concrete reaches the design strength, a pile foundation 2 with a waterproof structure 21 on the outer periphery is obtained.

[0124] Step (six), construct deformation buffer component 7:

[0125] The construction area was excavated manually, and the arched beam 71 was tied. The arched space below the arched beam 71 was separated by pre-placed gypsum board. Then, concrete was poured into the arched beam 71. After the concrete reached its strength, the soil was backfilled.

[0126] Step (seven), install rigid connector 5:

[0127] Insert the lower end of the rigid connector 5 into the cylindrical lower groove 23.

[0128] Step (eight), backfill the vibration damping groove 9:

[0129] Plain concrete was used to backfill the vibration damping groove 9.

[0130] Step (nine), construct the large-span pier beam 1:

[0131] The required steel reinforcement cage for the large-span pier beam 1 is tied above the pile foundation 2. The lower end of the steel pipe column 33 is welded to the steel reinforcement cage of the large-span pier beam 1. The welding position is at the steel reinforcement cage of the large-span pier beam 1 corresponding to the center line of the second set of elevated pier columns 32. The three sets of tensioning anchor cable components 4 and the large-span pier beam 1 are cast integrally. A through hole is reserved at the end of the large-span pier beam 1 for the rigid connector 5 to pass through. The lower end of the rigid connector 5 passes through the through hole and is inserted into the lower groove 23. Concrete is poured into the through hole and the lower groove 23. After the concrete reaches the required strength, a stable connection is achieved between the rigid connector 5, the pile foundation 2 and the large-span pier beam 1.

[0132] Step (10), prestressing of the curved anchor cable bundle 411:

[0133] After the large-span pier beam 1 is formed, the concrete pouring age should be no less than 7 days. Tensioning of the T1 and T2 groups of tensioning anchor cables is carried out in batches. The control stress of T1 group tensioning anchor cable component 41 is 1395 MPa, and the control stress of T2 group tensioning anchor cable component 42 is 1310 MPa. The elastic compression of concrete caused by the later batch of prestressing tensioning results in the prestress loss of the earlier batches. For the cast-in-place large-span pier beam 1, the batch tensioning, with the control stress of the earlier batches being higher than that of the later batches, can compensate for the prestress loss caused by the later batches, effectively improving the bending resistance of the large-span pier beam 1. After tensioning, the tensioning anchor cable component 4 is subjected to vacuum grouting using C40 cement. Vacuum grouting forms an integral whole between the prestressed steel bars and the concrete component, creating a unified anchorage; it also isolates the prestressed steel bars from air, placing them in the alkaline environment of the concrete grout, preventing oxidation and corrosion.

[0134] Step (XI), construct elevated pier 3:

[0135] The steel reinforcement cage required for the elevated pier columns 3 is tied and constructed. Simultaneously, a first steel pipe column 331 is installed at the center line of the first group of elevated pier columns 31. The lower end of the first steel pipe column 331 is inserted into the cylindrical upper groove 53 of the rigid connector 5. Concrete is poured into the upper groove 53. After the concrete solidifies, the first steel pipe column 331 is fixedly connected to the rigid connector 5, making the upper end of the first steel pipe column 331 flush with the top of the first group of elevated pier columns 31. Then, concrete is poured into the steel reinforcement cage until it reaches the design strength, forming the first group of elevated pier columns 31 and the second group of elevated pier columns 32.

[0136] Step (12), Install the viaduct box girder 6:

[0137] The viaduct box girder 6 is selected from precast components. The viaduct box girder 6 is hoisted onto the viaduct pier 3, and an inspection and confirmation are carried out after installation.

[0138] Step (thirteen), prestressing of the straight anchor cable bundle 411:

[0139] After installation, tensioning is performed on the T3 group of tensioning anchor cable components 43. The prestress generated at the mid-span of the large-span pier beam 1 counteracts the load, thereby improving the bending moment resistance of the large-span pier beam 1, protecting the subway station, and supporting the viaduct. The control stress for the T3 group of tensioning anchor cable components 43 is 1310 MPa. This process employs dual control of tension amount and tension force, with tension force as the primary factor. The allowable error between the measured and calculated elongation is controlled within ±6%. The tensioning status can be assessed, and if any deviations occur, the cause can be carefully analyzed, corrective measures can be proposed, and tensioning can continue to ensure that the tensioning process conforms to the design and that prestress is applied accurately.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A construction method for a long-span pier structure of an elevated bridge spanning a subway station, characterized in that, The elevated bridge long-span pier structure includes: a horizontally arranged long-span pier beam (1), at least two vertically arranged pile foundations (2) below the long-span pier beam (1), an elevated pier column (3) vertically arranged above the long-span pier beam (1), an elevated bridge box girder (6) horizontally arranged on the elevated pier column (3), and tension anchor cable components (4). The pile foundations (2) are evenly distributed on both sides of the long-span pier beam (1). The pile foundation (2) on one side and the elevated pier column (3) on the corresponding side are coaxially arranged. The coaxial elevated pier column (3) and the pile foundation (2) are connected by a rigid connector (5). Multiple sets of tension anchor cable components (4) are arranged inside the long-span pier beam (1). Multiple sets of tension anchor cable components (4) are spaced apart along the longitudinal direction of the long-span pier beam (1). The tension anchor cable components (4) can improve the bending resistance of the long-span pier beam (1). The elevated piers (3) are arranged in two rows, namely the first group of elevated piers (31) and the second group of elevated piers (32). The first group of elevated piers (31) is located at the edge above the large-span pier beam (1). The elevated piers (3) of the first group of elevated piers (31) are coaxially arranged with the pile foundation (2) on the corresponding side. The second group of elevated piers (32) is located in the middle above the large-span pier beam (1). The upper end of the rigid connector (5) passes through the large-span pier beam (1) and is connected to the first group of elevated piers (31). The lower end of the rigid connector (5) is connected to the upper end of the pile foundation (2). The rigid connector (5) includes a steel casting (51) and a lower reinforcing bar (52). The upper end of the steel casting (51) is provided with an upper groove (53), and the lower end is fixed to the lower reinforcing bar (52). The top of the pile foundation (2) is provided with a lower groove (23), and the lower reinforcing bar (52) is fixed in the lower groove (23). The center of the elevated pier (3) of the first group of elevated piers (31) is provided with a first steel pipe column (331). The top of the first steel pipe column (331) is fixedly connected to the elevated bridge box girder (6), and the lower part is inserted into the upper groove (53) and then fixedly connected. An angle reinforcement block (8) is provided at the connection between the large-span pier beam (1) and the pile foundation (2). The angle reinforcement block (8) is provided with a horizontal tie bar (81) and a plurality of oblique reinforcing bars (82). The plurality of reinforcing bars (82) are arranged in parallel and at intervals. One end of the reinforcing bar (82) is fixedly connected to the large-span pier beam (1) and the other end is fixedly connected to the pile foundation (2). One end of the tie bar (81) is fixedly connected to the large-span pier beam (1), and the other end is connected to the large-span pier beam (1) after passing through a plurality of reinforcing bars (82). The construction method includes the following steps: Step (1), construct the pile foundation (2) First, drill pile holes that meet the outer diameter of the pile foundation (2) on both sides of the existing subway station, and maintain the stability of the pile holes by using mud slurry wall protection; then, vertically place the steel cage into the pile hole, pour concrete into the steel cage, and obtain the pile foundation (2) after the concrete reaches the design strength; use the pre-supported template method to leave a lower groove (23) above the pile foundation (2), and insert the lower end of the rigid connector (5) into the lower groove (23); Step (two), constructing the large-span pier beam (1) The required steel reinforcement skeleton is constructed by binding the large-span pier beam (1) above the pile foundation (2), and the tensioning anchor cable component (4) and the large-span pier beam (1) are cast together. A through hole is reserved at the end of the large-span pier beam (1) for the rigid connector (5) to pass through. The upper end of the rigid connector (5) extends upward after passing through the through hole. Concrete is poured into the through hole and the lower groove (23). When the concrete reaches the strength, the rigid connector (5), the pile foundation (2) and the large-span pier beam (1) are stably connected. Step (3), construct the elevated piers (3) On the large-span pier beam (1), the steel reinforcement cage required for the construction of the elevated pier column (3) is tied and concrete is poured into the steel reinforcement cage until the design strength is reached to form the elevated pier column (3). Step (four), install the viaduct box girder (6) The viaduct box girder (6) is selected from precast components. The viaduct box girder (6) is hoisted onto the viaduct pier (3) and inspected and confirmed after installation.

2. The construction method for a long-span pier structure of an elevated bridge spanning a subway station according to claim 1, characterized in that, The tensioning anchor cable component (4) includes a pre-embedded pipe (412) arranged in the transverse direction of the large span pier beam (1), an anchor cable bundle (411) passing through the pre-embedded pipe (412), a tensioning end anchor (414) and a fixed end anchor (415) respectively set at both ends of the anchor cable bundle (411). One end of the anchor cable bundle (411) passes through the tensioning end anchor (414), and the other end is fixedly connected to the fixed end anchor (415). The pre-embedded pipe (412) is configured as a straight line and / or a curved line.

3. The construction method for a long-span pier structure of an elevated bridge spanning a subway station according to claim 1, characterized in that, A deformation buffer component (7) is provided between the large-span pier beam (1) and the subway station. The deformation buffer component (7) can provide deformation space for the large-span pier beam (1). The deformation buffer component (7) adopts an arched beam (71) which protrudes toward the large-span pier beam (1).

4. The construction method for a long-span pier structure of an elevated bridge spanning a subway station according to claim 1, characterized in that, The outer periphery of the pile foundation (2) is provided with a waterproof structure (21), which is formed by a double-liquid grouting method.

5. The construction method for a long-span pier structure of an elevated bridge spanning a subway station according to claim 1, characterized in that, The bottom of the pile foundation (2) is provided with an enlarged bottom pile (22), which can increase the vertical bearing capacity and pull-out force of the pile foundation (2).

6. The construction method for a long-span pier structure of an elevated bridge spanning a subway station according to claim 1, characterized in that, A damping groove (9) is provided between the subway station and the pile foundation (2), which can reduce the disturbance to the subway station during construction.

7. The construction method for a long-span pier structure of an elevated bridge spanning a subway station according to claim 1, characterized in that, In step (ii), there are at least three sets of tensioning anchor cable components (4). After the large span pier beam (1) is formed, two sets of tensioning anchor cable components (4) are tensioned, with one set having a control stress of 1395MPa and the other set having a control stress of 1310MPa. In step (iv), after installation, the remaining tensioned anchor cable components (4) are tensioned, and the controlled stress is 1310MPa.

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