Staged forming bridge and tunnel combined structure

Abstract

The invention relates to the technical field of building design and construction, in particular to a staged forming bridge and tunnel composite structure which comprises a frame tunnel, gate-type piers and a beam part, a bearing platform is arranged at the bottom of the frame tunnel, a pile foundation is arranged at the bottom of the bearing platform, and the bearing platform and the pile foundation are used for bearing an upper structure; the frame tunnel comprises two side walls and at least one middle wall, and the middle wall is located between the two side walls; the gate-type pier comprises two side buttresses, at least one middle buttress and a cover beam, the middle buttress is located between the two side buttresses, the side buttresses and the middle buttress are used for bearing the cover beam, and the beam part is arranged on the cover beam; the two side buttresses correspond to the two side walls in position, the middle buttresses correspond to the side buttresses in position, and the thickness of the middle buttresses is not larger than that of the middle walls; and a rear support is arranged between the top of the middle buttress and the cover beam, and the rear support is mounted after the gate-type pier and the beam part are loaded. The bridge and tunnel combined structure can effectively reduce occupation of the road width, and balance between structural stability and road space maximization is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of building design and construction, and in particular to a bridge-tunnel combination structure formed in stages. Background Art

[0002] In the process of urban construction, when a road passes through an intersection or railway, it is inevitable to have structures such as overpasses and underpasses. For example, at some busy intersections, the three-layer passages of overpasses, ground roads, and underpasses must ensure complete flow lines, forming a three-layer traffic pattern of air, ground, and underground.

[0003] Under normal construction conditions, the aerial layer often adopts a bridge span structure, and piers and foundations are set under certain span conditions, such as Figure 1 , Figure 2 The standard bridge cross section and pier structure of a certain project are shown; when the underground layer is not buried deep, rectangular frames are often used, such as Figure 3 A schematic diagram of the underpass framework of a certain project is shown.

[0004] In the overlapping section of the underpass frame and the aerial elevated section, there is a need to build the pier and frame tunnel together. In order to adapt to the arrangement of the piers and pile foundations, it is easy to think of a solution to directly combine the piers and the frame (for example Figure 4 , Figure 5 This solution has been used in some urban road construction, but because the bridge pier occupies the center of the road width and does not match the thickness of the wall in the frame, Figure 3 The solution shown or the solution of directly thickening the wall in the frame (for example Figure 6 , Figure 7 As shown in the figure, it will inevitably waste the limited space resources within the road red line. Even in the case of insufficient road construction width or demolition and other conditions, it may have a significant impact on the feasibility and economy of the entire construction plan. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art that a large amount of road width is occupied when constructing three-layer passages of underground, ground and bridge deck, resulting in a waste of road space, and to provide a staged forming bridge-tunnel combination structure.

[0006] In a first aspect, the present invention provides a staged bridge-tunnel composite structure, comprising a frame tunnel, a portal pier, and a beam portion, wherein a cap is provided at the bottom of the frame tunnel, a pile foundation is provided at the bottom of the cap, and the cap and the pile foundation are used to support a superstructure;

[0007] The frame tunnel comprises two side walls and at least one middle wall, wherein the middle wall is located between the two side walls;

[0008] The portal pier comprises two side piers, at least one middle pier and a cap beam, wherein the middle pier is located between the two side piers, the side piers and the middle pier are used to support the cap beam, and the beam portion is arranged on the cap beam;

[0009] The positions of the two side piers correspond to the positions of the two side walls, the position of the middle pier corresponds to the side piers, and the thickness of the middle pier is not greater than the thickness of the middle wall;

[0010] A post-support is arranged between the top of the middle pier and the cap beam, and the post-support is installed after the portal pier and the beam are loaded.

[0011] The staged forming bridge-tunnel combination structure provided by the present invention has a post-mounted support on the middle pier, which can release the bending moment of the middle pier, making it a theoretical axial load-bearing member, ensuring that the force of the middle pier is feasible; on the other hand, by placing the post-mounted support after the portal pier and the beam are loaded with the dead load and live load, the force condition of the middle pier can be actively adjusted according to the actual construction needs, and the limited load-bearing of the middle pier can be achieved. According to the actual construction process, the wall thickness restriction of the portal pier can be used to determine the reasonable design of the middle pier. For example, the thickness of the middle pier can be set to be consistent with the thickness of the middle wall, which effectively reduces the encroachment of the middle pier and the side pier on the road width, and achieves a balance between structural stability and maximum road space.

[0012] The staged forming bridge-tunnel combination structure provided by the present invention makes full use of the characteristics of different structures and integrates the portal piers, frame tunnels, pile foundations and pedestals. The combination of the middle pier and the rear support reduces the stress on the cap beam and the side piers, thereby reducing the height of the cap beam and the size of the side piers, avoiding the problem of occupying additional space due to thickening of the piers, and adapting to the municipal construction needs of three-layer underground, ground and bridge deck passages under complex environmental conditions such as limited net width and net height, greatly saving space and improving space utilization.

[0013] Preferably, the inner side wall of the side wall is aligned with the inner side wall of the side pier.

[0014] Aligning the inner wall of the side pier with the inner wall of the side wall can prevent the side pier from encroaching on the road width and further improve the utilization rate of the road space.

[0015] Preferably, the side wall and the side pier are an integrated structure.

[0016] The side wall and the side pier are set as an integrated structure. For example, the side wall and the side pier are designed as a whole during construction, and the steel bars are tied as a whole and cast together, which can make the staged bridge-tunnel composite structure have higher overall stability. This integrated structure can effectively disperse and transfer loads, avoid the stress concentration problem at the connection point that may occur in the traditional separated structure, and improve the seismic performance and impact resistance of the structure, so as to make the entire bridge-tunnel structure more stable and safe; at the same time, this integrated structure eliminates the connection gap between the side wall and the side pier in the traditional structure, thereby further reducing the occupation of road space, further releasing the use space of roads or other structures, and maximizing the utilization rate of road width.

[0017] Preferably, the number of the middle wall is one.

[0018] Preferably, the capping platforms are provided at the bottom of the middle wall and the side walls, and the pile foundations are provided at the bottom of the capping platforms.

[0019] Capping platforms and pile foundations are set at the bottom of the middle wall and side walls, which can better transfer the force of the portal pier and frame tunnel to the foundation and ensure the stability of the overall structure.

[0020] In a second aspect, the present invention provides a method for forming a bridge-tunnel combination structure in stages, which is used to implement the above-mentioned bridge-tunnel combination structure in stages, comprising the following steps:

[0021] S1: Construction of pile foundation, cap and bottom plate of frame tunnel;

[0022] S2: Construction of the frame tunnel and the lower part of the side piers;

[0023] S3: Construct side piers, cap beams and middle piers, and embed the support embedded parts of the post-installed support on the top of the middle pier;

[0024] S4: After constructing the beam, connect the middle pier and the cap beam through the post-support.

[0025] The method for forming a bridge-tunnel composite structure in stages provided by the present invention is constructed in stages, and the construction of pile foundations, pedestals and frame tunnel bottom plates is arranged in the first stage, providing a stable foundation support structure. In the subsequent stages, the frame tunnel, side piers, middle piers and cap beams are constructed step by step, and finally the middle piers and cap beams are connected by post-supports. On the one hand, the bending moment of the middle pier can be released, making it a theoretical axial load-bearing member, ensuring that the force of the middle pier is feasible; on the other hand, by placing the post-supports after the portal pier and the beam are loaded with constant loads and live loads, the force of the middle pier can be actively adjusted according to the actual construction needs, and the limited load of the middle pier can be achieved. According to the actual construction process, the wall thickness of the portal pier is limited to determine the reasonable design of the middle pier. For example, the thickness of the middle pier can be set to be consistent with the thickness of the middle wall, effectively reducing the encroachment of the middle pier and the side pier on the road width, and achieving a balance between structural stability and maximum road space.

[0026] Preferably, in S1, the pile foundation is constructed by the drilling and grouting method, and the pile head reinforcement is exposed.

[0027] After the pile foundation is constructed by the drilling and pouring method, the pile head steel bars are exposed to the surface, so that the pile foundation and the cap can be effectively connected through the steel bars. In the subsequent construction, the exposed steel bars and the cap concrete can form a stable anchor, improve the overall rigidity and structural strength between the pile foundation and the cap, and ensure the stable support of the superstructure.

[0028] Preferably, the steel bars in the frame tunnel of S2 and the lower part of the side piers are integrally tied and cast together.

[0029] After the steel bars of the frame tunnel and the side piers are tied together as a whole, an interconnected steel skeleton is formed. This setting enables the frame tunnel and the side piers to form an integral structure, improves the overall rigidity and bending resistance after pouring concrete, makes the connection between the frame tunnel and the side piers more solid, and reduces the risk of structural separation and dislocation.

[0030] Preferably, after the load of the S4 middle beam portion is loaded to 50%-100%, the middle pier is connected to the cap beam through a rear support.

[0031] The rear support can be installed after the beam load is set to 50%-100%. The load on the middle pier can be selected according to the actual land use needs during construction and the design requirements of the middle pier, which improves the flexibility of construction and achieves a balance between structural stability and maximization of road space.

[0032] Preferably, after the load of the S4 middle beam portion is loaded to 50% or 100%, the middle pier is connected to the cap beam through a post-mounted support.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The staged forming bridge-tunnel combination structure provided by the present invention has a post-mounted support arranged on the middle pier, which can release the bending moment of the middle pier, making it a theoretical axial force-bearing member, ensuring that the force of the middle pier is feasible; on the other hand, by placing the post-mounted support after the portal pier and the beam are loaded with the dead load and live load, the force of the middle pier can be actively adjusted according to the actual construction requirements to achieve the limited load of the middle pier. According to the actual construction process, the wall thickness of the portal pier is limited to determine the reasonable design of the middle pier. For example, the thickness of the middle pier can be set to be consistent with the thickness of the middle wall, effectively reducing the encroachment of the middle pier on the road width, and achieving a balance between structural stability and maximum road space;

[0035] 2. The staged forming bridge-tunnel combination structure provided by the present invention makes full use of the characteristics of different structures and integrates the portal piers, frame tunnels, pile foundations and caps. The combination of the middle pier and the rear support, on the one hand, realizes the controllable size of the middle pier, and on the other hand, greatly improves the stress on the cap beam and the side piers. By adding the middle pier, the calculated span of the cap beam is reduced, thereby greatly reducing the maximum bending moment and maximum shear force of the cap beam, achieving a significant reduction in the height of the cap beam and the size of the side piers, avoiding the problem of occupying extra space due to the large size of the cap beam and the side piers, and adapting to the municipal construction needs of underground, ground and bridge deck three-layer passages under complex environmental conditions such as limited net width and net height, greatly saving space and improving space utilization;

[0036] 3. The staged forming bridge-tunnel combination structure provided by the present invention changes the mode in which the traditional frame relies on the frame bottom plate to transfer the force of the upper structure. The main force of the upper structure is directly transferred to the abutment and pile foundation through the side and middle piers, which can reduce the thickness of the frame tunnel bottom plate to a certain extent. If the hydrological and geological conditions permit, the reinforced concrete bottom plate of the frame tunnel can also be cancelled, further reducing the number of projects and saving project investment.

[0037] 4. The method for forming a bridge-tunnel composite structure in stages provided by the present invention is constructed in stages, and the construction of pile foundations, pedestals and frame tunnel bottom plates is arranged in the first stage, providing a stable foundation support structure. In subsequent stages, the frame tunnel, side piers, middle piers and cap beams are constructed step by step, and finally the middle piers and cap beams are connected by post-mounted supports. On the one hand, the pile foundation, pedestal, frame tunnel and portal pier are organically combined to avoid the separation of the pedestal and the frame, and the separation of the portal pier and the frame tunnel, which greatly saves the amount of engineering and investment. By placing the post-mounted supports after the portal pier and the beam are loaded with the constant load and live load, the stress condition of the middle pier can be actively adjusted according to the actual construction needs, and the limited load of the middle pier can be achieved, so as to further reduce the pile arrangement of the lower wall in the frame tunnel, and form a reasonable distribution of the stiffness of the wall, column and pile foundation and match the structural design. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of a standard bridge cross section for a project;

[0039] Figure 2 for Figure 1 Schematic diagram of the middle bridge pier;

[0040] Figure 3 A schematic diagram of the underpass framework for a project;

[0041] Figure 4 A cross-sectional diagram of a standard bridge and an underpass frame directly combined and set up for a certain project;

[0042] Figure 5 for Figure 4 Schematic diagram of the middle bridge pier;

[0043] Figure 6 This is a cross-sectional diagram of a project where a standard bridge and a thickened underpass frame are directly combined and set up;

[0044] Figure 7 for Figure 6 Schematic diagram of the middle bridge pier;

[0045] Figure 8 A schematic cross-sectional view of the staged-forming bridge-tunnel combination structure provided in Example 1;

[0046] Fig. 9 for Figure 8 Schematic diagram of the middle bridge pier;

[0047] Fig.10 for Figure 8 The side view after the beam is hidden in the middle;

[0048] Fig.11 This is a schematic diagram of the structure when constructing the pile foundation, cap and bottom plate of the frame tunnel for S1;

[0049] Fig.12 This is a schematic diagram of the structure of S2 when constructing the frame tunnel and the lower part of the side pier;

[0050] Fig.13 Structural diagram of S3 when constructing side piers, cap beams, middle piers, and pre-embedded bearings and embedded parts;

[0051] Fig.14A This is a structural diagram of the constructed beam without installing the rear support.

[0052] Fig. 14B This is a schematic diagram of the structure after the rear support is installed;

[0053] Fig.15 Finite element models constructed for Example 3, Example 4 and Comparative Example 1;

[0054] Fig.16 is the standard load combination-cap beam bending moment diagram in Example 3, unit KN.m;

[0055] Fig.17 is the standard load combination-cap beam shear force diagram in Example 3, unit KN;

[0056] Fig.18 is the standard load combination-mid-pier axial force diagram in Example 3, unit KN;

[0057] Fig.19 is the standard load combination-cap beam bending moment diagram in Example 4, unit KN.m;

[0058] Fig. 20 is the standard load combination-cap beam shear force diagram in Example 4, unit KN;

[0059] Fig.21 is the standard load combination-middle pier axial force diagram in Example 4, unit KN;

[0060] Fig. 22 Schematic diagram of the cross section of the bridge-tunnel combination structure of Comparative Example 1;

[0061] Fig.23 It is the standard load combination-cap beam bending moment diagram in comparative example 1, unit KN.m;

[0062] Fig.24 is the standard load combination-cap beam shear force diagram in comparative example 1, unit KN;

[0063] Fig.25 It is the standard load combination-middle pier axial force diagram in comparative example 1, unit KN;

[0064] Fig.26 Schematic diagram of the cross section of the bridge-tunnel combination structure of Comparative Example 2;

[0065] Fig. 27 Finite element model constructed for comparative example 2;

[0066] Fig.28 It is the standard load combination-cap beam bending moment diagram in comparative example 2, unit KN.m;

[0067] Fig.29 is the standard load combination-cap beam shear force diagram in comparative example 2, unit KN;

[0068] Fig.30 It is the standard load combination-cap beam axial force diagram in comparative example 2, unit KN.

[0069] Markings in the figure:

[0070] 1-frame tunnel, 11-side wall, 12-middle wall, 2-portal pier, 21-side supporting pier, 22-middle supporting pier, 23-cap beam, 3-beam, 4-capping platform, 5-pile foundation, 6-rear support. DETAILED DESCRIPTION

[0071] The present invention is further described in detail below in conjunction with specific embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0072] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are all based on the expression of the orientation or position relationship shown in the drawings, or are the orientation or position relationship when the invented product / equipment / device is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.

[0073] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0074] In addition, the expressions “first”, “second”, “third”, etc., which appear in the terms, are merely used to distinguish the description of the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0075] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0076] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0077] Example 1

[0078] like Figure 8 , Fig. 9 , Fig.10 As shown, this embodiment provides a staged bridge-tunnel composite structure, including a frame tunnel 1, a portal pier 2, and a beam 3. A cap 4 is arranged at the bottom of the frame tunnel 1, and a pile foundation 5 is arranged at the bottom of the cap 4. The cap 4 and the pile foundation 5 are used to support the superstructure. Here, the superstructure can be understood to refer to the load of all structures above the cap 4.

[0079] The frame tunnel 1 includes two side walls 11 and at least one middle wall 12, wherein the middle wall 12 is located between the two side walls 11; Figure 8 As shown, in this embodiment, the frame tunnel 1 adopts a double-hole frame, and only one middle wall 12 is arranged between the two side walls 11.

[0080] The portal pier 2 includes two side piers 21, at least one middle pier 22 and a cap beam 23. The middle pier 22 is located between the two side piers 21. The side piers 21 and the middle pier 22 are used to support the cap beam 23. The beam portion 3 is arranged on the cap beam 23.

[0081] The positions of the two side piers 21 correspond to the positions of the two side walls 11, that is, the side piers 21 are also set at the places where the side walls 11 are set in this embodiment; the position of the middle pier 22 corresponds to the side pier 21. This embodiment adopts a double-hole frame. It can be understood that the number of the corresponding piers 22 in this embodiment is also one, and the middle wall 12 and the middle pier 22 can be set at one-half of the two side walls 11; the thickness of the middle pier 22 is not greater than the thickness of the middle wall 12, and preferably the thickness of the middle pier 22 is equivalent to the thickness of the middle wall 12; preferably, the inner side wall of the side wall 11 in this embodiment can be aligned with the inner side wall of the side pier 21, that is, Fig. 9 As shown, the side support piers 21 are arranged in this way without encroaching on the internal space of the frame tunnel 1, thus preventing the side support piers 21 from encroaching on the road width, and further improving the utilization rate of the road space.

[0082] Preferably, in this embodiment, the side wall 11 and the side pier 21 are an integrated structure. For example, the side wall 11 and the side pier 21 are designed as a whole during construction, and the steel bars are tied as a whole and cast together, which can make the staged bridge-tunnel composite structure have higher overall stability. This integrated structure can effectively disperse and transfer loads, avoid the stress concentration problem at the connection point that may occur in the traditional separated structure, and improve the seismic performance and impact resistance of the structure, so that the entire bridge-tunnel structure is more stable and safe; at the same time, this integrated structure eliminates the connection gap between the side wall 11 and the side pier 21 in the traditional structure, thereby further reducing the occupation of road space, further releasing the use space of roads or other structures, and maximizing the utilization rate of road width.

[0083] A rear support 6 is arranged between the top of the middle pier 22 and the cap beam 23 , and the rear support 6 is installed after the portal pier 2 and the beam portion 3 are loaded.

[0084] Preferably, if Figure 8 As shown, the bottom of the middle wall 12 and the side wall 11 are provided with a cap 4, and the bottom of the cap 4 is provided with a pile foundation 5. The cap 4 and the pile foundation 5 are provided at the bottom of the middle wall 12 and the side wall 11, which can better transfer the force of the portal pier 2 and the frame tunnel 1 to the foundation, ensuring the stability of the overall structure.

[0085] The staged forming bridge-tunnel combination structure provided in this embodiment has a rear support 6 set on the middle pier 22. On the one hand, the bending moment of the middle pier 22 can be released, making it a theoretical axial load-bearing member, ensuring that the force of the middle pier 22 is feasible; on the other hand, by placing the rear support 6 after the portal pier 2 and the beam 3 are loaded with constant load and live load, the force condition of the middle pier 22 can be actively adjusted according to actual construction needs, and the limited load of the middle pier 22 can be achieved. According to the actual construction process, the wall thickness restriction of the portal pier 2 can be used to determine a reasonable design of the middle pier 22. For example, the thickness of the middle pier 22 can be set to be consistent with the thickness of the middle wall 12, so as to effectively reduce the encroachment of the middle pier 22 and the side pier 21 on the road width, and achieve a balance between structural stability and maximum road space.

[0086] The staged forming bridge-tunnel combination structure provided by the present invention makes full use of the characteristics of different structures, and integrates the portal pier 2, frame tunnel 1, pile foundation 5 and pedestal 4. The combination of the middle pier 22 and the rear support 6 reduces the force on the cap beam 23 and the side pier 21, thereby reducing the height of the cap beam 23 and the size of the side pier 21, avoiding the problem of occupying additional space due to thickening of the bridge piers, and adapting to the municipal construction needs of underground, ground and bridge deck three-layer passages under complex environmental conditions such as limited net width and net height, greatly saving space and improving space utilization.

[0087] Example 2

[0088] This embodiment provides a method for forming a bridge-tunnel combination structure formed in stages, which is used to implement the bridge-tunnel combination structure formed in stages provided in Embodiment 1, and includes the following steps:

[0089] S1: Fig.11 As shown, the pile foundation 5 is constructed by drilling and pouring method and the pile head reinforcement is exposed; the cap 4 and the bottom plate of the frame tunnel 1 are constructed;

[0090] After the pile foundation 5 is constructed by the drilling and pouring method, the pile head steel bars are exposed to the surface, so that the pile foundation 5 and the cap 4 can be effectively connected by the steel bars. In the subsequent construction, the exposed steel bars and the concrete of the cap 4 can form a stable anchor, improve the overall rigidity and structural strength between the pile foundation 5 and the cap 4, and ensure the stable support of the upper structure.

[0091] S2: Fig.12 As shown, the entire frame tunnel 1 and the lower part of the side pier 21 are constructed, where the steel bars of the frame tunnel 1 and the lower part of the side pier 21 are tied together and cast together. It can be understood that the lower part of the side pier 21 here refers to the part of the side pier 21 that is slightly higher than the frame tunnel 1;

[0092] After the steel bars of the frame tunnel 1 and the side pier 21 are tied together as a whole, an interconnected steel skeleton is formed. This arrangement enables the frame tunnel 1 and the side pier 21 to form an integral structure, improves the overall rigidity and bending resistance after pouring concrete, makes the connection between the frame tunnel 1 and the side pier 21 more solid, and reduces the risk of separation and dislocation of the structure.

[0093] S3: Fig.13 As shown, the side piers 21 , the cap beam 23 and the middle pier 22 are constructed, and the support embedded parts of the rear support 6 are embedded in the top of the middle pier 22 .

[0094] S4: After constructing the beam portion 3, the middle support 22 and the cap beam 23 are connected by the rear support 6.

[0095] like Fig.14A FIG. 3 shows a schematic diagram of a beam portion 3 having been constructed but without installing a rear support 6. Fig. 14B As shown, the middle pier 22 is connected to the cap beam 23 through the rear support 6;

[0096] Alternatively, after the beam portion 3 is loaded to 50%, the rear support 6 may be installed, and the middle support 22 may be connected to the cap beam 23 through the rear support 6;

[0097] You can also choose to install the rear support 6 after the load on the beam 3 reaches 50%-100%, such as 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, based on actual construction needs, and connect the middle pier 22 with the cap beam 23 through the rear support 6.

[0098] The method for forming a bridge-tunnel composite structure in stages provided in this embodiment is constructed in stages, and the construction of the pile foundation 5, the pedestal 4 and the bottom plate of the frame tunnel 1 is arranged in the first stage, providing a stable foundation support structure. In subsequent stages, the frame tunnel 1, the side piers 21, the middle pier 22 and the cap beam 23 are constructed step by step, and finally the middle pier 22 and the cap beam 23 are connected by the rear support 6. On the one hand, the bending moment of the middle pier 22 can be released, making it a theoretical axial load-bearing member, ensuring that the force of the middle pier 22 is feasible; on the other hand, by placing the rear support 6 after the portal pier 2 and the beam 3 are loaded with constant load and live load, the force condition of the middle pier 22 can be actively adjusted according to actual construction needs, and the limited load of the middle pier 22 can be achieved. According to the actual construction process, the wall thickness restriction of the portal pier 2 is determined to determine a reasonable design of the middle pier 22. For example, the thickness of the middle pier 22 can be set to be consistent with the thickness of the middle wall 12, which effectively reduces the encroachment of the middle pier 22 and the side pier 21 on the road width, and achieves a balance between structural stability and maximum road space.

[0099] Example 3

[0100] Take an actual construction project as an example. The existing streets in this project are narrow and it is necessary to build three-level passages: underground, ground and bridge deck. If the conventional standard bridge is directly combined with the underpass frame, for example Figure 4 As shown, or the standard bridge is directly combined with the underpass frame with thickened middle wall, for example Figure 6 As shown, the total width of the structure reaches 51m, which will cause the road width to encroach on the residential area, making demolition extremely difficult. Therefore, it is necessary to use the staged forming bridge-tunnel composite structure forming method provided in Example 2, and construct the staged forming bridge-tunnel composite structure provided in Example 1, with the cross-sectional dimensions of the cap beam 23 being 3.2×2.8m, the cross-sectional dimensions of the middle pier being 1×0.5m (with the same thickness as the middle wall 12), and the cross-sectional dimensions of the side pier 21 being 3x2.5m, so as to adapt to the three-layer channel structure design scheme under space-constrained conditions.

[0101] By constructing a finite element model for theoretical analysis, the analysis and calculation are performed according to the allowable stress method, such as Fig.15 The finite element model of the three-column portal pier-double-hole frame-pile foundation bridge-tunnel composite structure is shown in the figure. The basic situation of the structure is: the upper structure carried by this pier is a simply supported box beam with a span of 30 meters, and its bridge deck width is 28 meters. The design live load of this bridge is urban-class A live load. The cap beam adopts C50 reinforced concrete, and the pier column adopts C35 concrete.

[0102] For the case where the middle pier 22 bears 100% of the dead load and live load of the beam 3, the internal force is calculated by finite element model. The results are as follows: Fig.16 , Fig.17 , Fig.18 As shown in the figure, it can be seen that the maximum negative bending moment of the cap beam 23 of the present embodiment is -22683KN.m, the maximum shear force of the cap beam 23 is 6173KN, the maximum axial force of the middle pier 22 is 6601KN, and the minimum axial force is 6695KN.

[0103] Example 4

[0104] Different from the third embodiment, the present embodiment is to calculate the internal force by the finite element model for the case where the middle pier 22 bears 50% of the dead load and live load of the beam 3. The finite element model is as follows: Fig.15 The calculation results of internal forces are shown as Fig.19 , Fig. 20 , Fig.21 As shown in the figure, it can be seen that the maximum negative bending moment of the cap beam 23 of the embodiment is -28965KN.m, the maximum shear force of the cap beam 23 is 7164KN, the maximum axial force of the middle pier 22 is 4620KN, and the minimum axial force is 4717KN.

[0105] Comparative Example 1

[0106] Different from Example 3, this comparative example does not have a rear support 6. The cross-sectional schematic diagram of the bridge-tunnel combination structure of this comparative example is as follows: Fig. 22 As shown, during construction, the middle pier 22 in S3 is directly fixed to the cap beam 23, and the rear support 6 is not installed in S4.

[0107] This comparative example adopts the consolidation scheme of the middle pier 22 for finite element analysis and the allowable stress method for analysis. The finite element model is as follows Fig.15 The calculation results of internal forces are shown as Fig.23 , Fig.24 , Fig.25 As shown in the figure, it can be seen that the maximum negative bending moment of the cap beam 23 of the comparative example is -15673KN.m, the maximum shear force of the cap beam 23 is 5062KN, the maximum axial force of the middle pier 22 is 8825KN, and the minimum axial force is 8922KN.

[0108] Comparative Example 2

[0109] Different from Example 3, the comparative example does not have the middle support pier 22 and the rear support 6. The cross-sectional schematic diagram of the bridge-tunnel combination structure of the comparative example is as follows: Fig.26As shown, during construction, the middle support 22 is not constructed in S3, and the rear support 6 is not installed in S4. That is, the finite element model of the double-column portal pier-double-hole frame-pile foundation bridge-tunnel combined structure is constructed in this comparative example. Fig. 27 The calculation results of internal force are shown in Fig.28 , Fig.29 , Fig.30 As shown in the figure, it can be seen that the maximum negative bending moment of the cap beam 23 of the comparative example is -42121 KN.m, and the maximum shear force of the cap beam 23 is 10234 KN.

[0110] In summary, Table 1 shows the calculation results of cap beam strength and cracks for each scheme:

[0111] Table 1 Summary of calculation results of cap beam strength and cracks for each scheme

[0112]

[0113] As can be seen from Table 1, since the comparative example 2 does not use the middle pier 22, its cap beam 23 is subjected to large forces, and the cracks of ordinary reinforced concrete exceed the limit, which does not meet the design requirements.

[0114] Table 2 shows the calculation results of the strength and cracks of the pier 22 in each scheme. As can be seen from Table 2, the concrete compressive stress of Example 1 exceeds the limit and does not meet the design requirements, while Examples 3 and 4 use different post-bearing timings of the middle pier 22, which can effectively adjust the force of the middle pier 22 and determine a reasonable design of the middle pier 22 according to the actual construction process.

[0115] Through comparison, it is found that among the four solutions of Example 3, Example 4, Comparative Example 1 and Comparative Example 2, the bending moment and shear force on the cap beam 23 of Comparative Example 2 are the largest.

[0116] Through comparison, it is also found that among the three schemes of Example 3, Example 4 and Comparative Example 1: the negative bending moment borne by the cap beam 23 of Comparative Example 1 is the smallest among the three schemes, the maximum shear force borne by the cap beam 23 is the smallest among the three schemes, and the axial force of the middle pier 22 is the largest among the three schemes; the negative bending moment borne by the cap beam 23 of Example 4 is the largest among the three schemes, the maximum shear force borne by the cap beam 23 is the largest among the three schemes, and the axial force of the middle pier 22 is the smallest among the three schemes.

[0117] In summary, compared with Comparative Examples 1 and 2, the solution of Example 3 or Example 4 adjusts the size of the rear bearing of the middle pier 22 to make the structure reasonable and feasible, and the sizes of the cap beam 23 and the middle pier 22 controllable to meet the needs of on-site layout.

[0118] Table 2 Summary of calculation results of pier strength and cracks

[0119]

[0120] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A bridge-tunnel combination structure formed in stages, characterized in that: It comprises a frame tunnel (1), a portal pier (2), and a beam portion (3); a cap (4) is arranged at the bottom of the frame tunnel (1); a pile foundation (5) is arranged at the bottom of the cap (4); the cap (4) and the pile foundation (5) are used to support the upper structure; The frame tunnel (1) comprises two side walls (11) and at least one middle wall (12), wherein the middle wall (12) is located between the two side walls (11); The portal pier (2) comprises two side piers (21), at least one middle pier (22) and a cap beam (23), wherein the middle pier (22) is located between the two side piers (21), the side piers (21) and the middle pier (22) are used to support the cap beam (23), and the beam portion (3) is arranged on the cap beam (23); The positions of the two side piers (21) correspond to the positions of the two side walls (11), the position of the middle pier (22) corresponds to the side piers (21), and the thickness of the middle pier (22) is not greater than the thickness of the middle wall (12); A rear support (6) is arranged between the top of the middle pier (22) and the cap beam (23), and the rear support (6) is installed after the portal pier (2) and the beam portion (3) are loaded.

2. The staged-forming bridge-tunnel combination structure according to claim 1 is characterized in that: The inner side wall of the side wall (11) is aligned with the inner side wall of the side pier (21).

3. The staged-forming bridge-tunnel combination structure according to claim 1 is characterized in that: The side wall (11) and the side supporting pier (21) are an integrated structure.

4. The staged-forming bridge-tunnel combination structure according to claim 1 is characterized in that: The number of the middle wall (12) is one.

5. The staged-forming bridge-tunnel combination structure according to claim 1 is characterized in that: The base (4) is disposed at the bottom of the middle wall (12) and the side wall (11), and the pile foundation (5) is disposed at the bottom of the base (4).

6. A method for forming a bridge-tunnel composite structure in stages, characterized in that: The method for implementing the staged forming bridge-tunnel combination structure according to any one of claims 1 to 5 comprises the following steps: S1: Construction of pile foundation (5), cap (4) and bottom plate of frame tunnel (1); S2: Construction of the frame tunnel (1) and the lower part of the side support pier (21); S3: constructing the side piers (21), the cap beam (23) and the middle pier (22), and pre-embedding the support embedded parts of the rear support (6) on the top of the middle pier (22); S4: After constructing the beam portion (3), the middle pier (22) and the cap beam (23) are connected via the rear support (6).

7. The method for forming a bridge-tunnel composite structure in stages according to claim 6, characterized in that: In S1, the pile foundation (5) is constructed by the drilling and pouring method, and the pile head steel bars are exposed.

8. The method for forming a bridge-tunnel composite structure in stages according to claim 6, characterized in that: The steel bars of the frame tunnel (1) and the lower part of the side pier (21) of S2 are integrally tied and cast together.

9. The method for forming a bridge-tunnel composite structure in stages according to claim 6, characterized in that: After the load of the S4 middle beam portion (3) is loaded to 50%-100%, the middle pier (22) is connected to the cap beam (23) through the rear support (6).

10. The method for forming a bridge-tunnel composite structure in stages according to claim 6, characterized in that: After the load of the S4 middle beam portion (3) is loaded to 50% or 100%, the middle pier (22) is connected to the cap beam (23) through the rear support (6).

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