Bridge-lining combined structure with tunnel spanning function and construction method thereof

Abstract

The present invention relates to a bridge-lining combined structure with a tunnel spanning function and a construction method thereof, and belongs to the field of bridge-tunnel structures. It includes a bridge deck, and supporting longitudinal beams are fixed on both sides of the width direction below the bridge deck, and a plurality of transversely arranged supporting crossbeams are fixed on the lower end surface of the bridge deck. The supporting crossbeams are evenly spaced, and the two ends of the supporting crossbeams are respectively passed through the supporting longitudinal beams and fixedly connected with the tunnel primary support steel frame in the tunnel as a whole. The inner side of the tunnel primary support steel frame is the tunnel secondary lining, and the transverse steel bars of the tunnel secondary lining are anchored in the supporting longitudinal beams. The end supporting crossbeams are located at the two ends of the space to be spanned in the tunnel, and the end supporting crossbeams are fixedly connected with the supporting longitudinal beams as a whole. The supporting longitudinal beams are extended to a certain length to the non-bridge span sections in the tunnels at both ends and placed on the surrounding rock, and the tunnel pile foundation in the tunnel is arranged at the intersection of the end supporting crossbeams and the supporting longitudinal beams. The structure has greater rigidity and stability than the traditional tunnel bridge structure.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel engineering and structural engineering, and relates to a bridge-lining combined structure with a tunnel spanning function and a construction method thereof. Background Art

[0002] Sometimes in tunnel engineering, there are situations where you need to cross structures (such as other tunnels) or special obstacles (such as underground caverns) at close range. In this case, a bridge structure is usually set up in the tunnel to cross these obstacles. Traditional tunnel bridge structures have the following problems:

[0003] 1. If the longitudinal length of the space spanned by the tunnel exceeds the cross-sectional width of the tunnel, the load of the tunnel lining will be fully transferred to the bridge structure, causing the beams close to the arch foot of the tunnel lining to be subjected to great stress, while the beams in the middle far from the tunnel lining will only bear the load of the car, resulting in uneven load distribution of the entire structure and unreasonable stress;

[0004] 2. When the span of the bridge in the tunnel is large, the load transferred to the bridge by the tunnel lining will be very large. The traditional bridge structure uses a simply supported beam or simply supported plate, which requires a large cross-section and reinforcement, and is very expensive;

[0005] 3. The pile foundation in the tunnel is subject to a large load at the part close to the arch foot of the tunnel lining, while the pile foundation in the middle far away from the tunnel lining only bears the load of the car. The load distribution is very uneven, the foundation force is unreasonable, and a large cap is required to distribute the load. In addition, a large number of pile foundations are required, while some pile foundations are subject to relatively small forces, resulting in great engineering waste. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a bridge-lining combined structure with a tunnel spanning function and a construction method thereof, so as to be used in dark-excavated tunnels that require spanning in the tunnel.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A bridge-lining combined structure with a tunnel crossing function comprises a bridge deck, supporting longitudinal beams are fixed on both sides of the width direction below the bridge deck, a plurality of transversely arranged supporting cross beams are fixed on the lower end face of the bridge deck, the supporting cross beams are evenly spaced, both ends of the supporting cross beams respectively pass through the supporting longitudinal beams and are fixedly connected with the tunnel primary support steel frame in the tunnel as a whole, the inner side of the tunnel primary support steel frame is the tunnel secondary lining, the transverse steel bars of the tunnel secondary lining are anchored in the supporting longitudinal beams, the end supporting cross beams are located at the two ends of the space to be crossed in the tunnel, the end supporting cross beams and the supporting longitudinal beams are fixedly connected as a whole, and the tunnel pile foundation in the tunnel is arranged at the intersection of the end supporting cross beams and the supporting longitudinal beams.

[0009] Furthermore, the supporting longitudinal beams extend to the non-bridge span sections in the tunnel at the bottom of the tunnel on both sides and are supported on the surrounding rock.

[0010] Furthermore, the length of the supporting longitudinal beam extending into the rock mass at the bottom of the tunnel on both sides is 0.6B, where B is the span of the space to be crossed.

[0011] Furthermore, the spacing of the supporting cross beams corresponds to the spacing of the primary supporting steel frames of the tunnel, and the spacing of the supporting cross beams is an integer multiple of the spacing of the primary supporting steel frames of the tunnel.

[0012] The construction method of the bridge-lining combined structure with tunnel spanning function mainly includes the following steps:

[0013] S1: The primary support steel frame and secondary lining of the tunnel are constructed according to the traditional tunnel construction method, and steel bars and steel section joints are reserved at the arch feet of the primary support steel frame and the secondary lining of the tunnel respectively;

[0014] S2: Tunnel pile foundation in the construction tunnel;

[0015] S3: Construction support longitudinal beams and support cross beams;

[0016] S4: dig out a space for the bridge deck above the supporting longitudinal beams and the supporting cross beams, and pour concrete in the space to form the bridge deck; wherein: when the space to be crossed under the tunnel is constructed after the tunnel, the specific steps of S3 are:

[0017] Excavate the space required for the bridge span structure in the tunnel, including the space for the supporting longitudinal beams to extend into the tunnels at both ends, and the space for the end supporting cross beams, which are located between the pouring spaces of the two supporting longitudinal beams at the tunnel pile foundation; install the steel structure of the supporting cross beams, and weld them to the reserved steel joints of the arch foot of the tunnel primary support steel frame;

[0018] The steel bars of the supporting longitudinal beam are installed in the excavated space of the supporting longitudinal beam, so that the steel bars of the supporting longitudinal beam and the steel bar joints reserved for the arch foot of the secondary lining of the tunnel are fixed as a whole through the tunnel foot locking anchor rod, and the steel bars of the end supporting cross beam are installed in the space of the end supporting cross beam, so that the two ends of the steel bars of the end supporting cross beam are respectively welded to the steel bars of the supporting longitudinal beam as a whole, and concrete is poured in the space of the supporting longitudinal beam and the space of the end supporting cross beam to form a reinforced concrete beam; when the spanning space has been formed, the specific steps of S3 are:

[0019] First, dig the space of the supporting longitudinal beam on one side and quickly pour concrete to form the supporting longitudinal beam. The steel bars of the supporting longitudinal beam are placed in the space of the supporting longitudinal beam. At the same time, the supporting cross beam and the steel joint are pre-buried in the supporting longitudinal beam.

[0020] Then, the space of the supporting longitudinal beam on the other side is excavated and concrete is quickly poured to form the supporting longitudinal beam. The steel bars of the supporting longitudinal beam are placed in the space of the supporting longitudinal beam. Meanwhile, the supporting cross beam and the steel joint are pre-buried in the supporting longitudinal beam. The steel bars of the end supporting cross beam are installed in the space of the end supporting cross beam, and concrete is poured in the space of the end supporting cross beam to form a reinforced concrete beam.

[0021] Construct the steel structure of the remaining supporting crossbeam in the middle part between the two supporting longitudinal beams and weld it into a whole with the steel joint of the supporting crossbeam embedded in the supporting longitudinal beam.

[0022] Furthermore, the tunnel pile foundation adopts a manual hole digging process. After the holes are dug manually, the steel bars of the tunnel pile foundation are placed, and then concrete is poured into the holes to form four tunnel pile foundations for support.

[0023] Furthermore, when the space to be crossed under the tunnel is constructed after the tunnel is built, step S5 is also included: constructing the crossing space under the tunnel, directly excavating the surrounding rock to the edge of the bridge span structure, without taking other support measures.

[0024] The beneficial effects of the present invention are:

[0025] 1. The main load-bearing structural support beam of the bridge span system is connected to the secondary lining of the tunnel as a whole, which greatly improves the stiffness and bearing capacity of the support beam, and solves the problem that the traditional tunnel bridge structure uses an independent bridge structure with unreasonable load bearing, requires a larger section and reinforcement, is difficult to implement and has a high cost;

[0026] 2. The supporting crossbeam is connected to the tunnel primary support steel frame as a whole, so that the entire span structure can be locked on the surrounding rock with the help of the tunnel locking anchor rods and system anchor rods on the tunnel lining, further improving the stress of the span structure and solving the problem of insufficient stiffness and bearing capacity of the traditional tunnel bridge structure when subjected to a large load transmitted by the lining;

[0027] 3. By extending the supporting longitudinal beams to both ends, the elastic foundation beams on both sides and the tunnel pile foundation bear the load together, which greatly reduces the load on the pile foundation and improves its stress. This avoids the problem that the traditional tunnel bridge structure needs to use a large number of pile foundations to meet the bearing capacity requirements, and the stress between the pile foundations is very uneven, resulting in a large engineering waste;

[0028] 4. The entire bridge span system is organically combined with the tunnel lining system, which has greater rigidity and stability than the traditional tunnel bridge structure and greatly improves the economic efficiency.

[0029] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0031] Figure 1 A schematic diagram of the cross-sectional structure of the invention;

[0032] Figure 2 A top view created for the present invention;

[0033] Figure 3 It is a schematic diagram of the longitudinal section structure created by the present invention.

[0034] Reference numerals:

[0035] 1. Bridge deck; 2. Supporting longitudinal beams; 3. Supporting cross beams; 4. End supporting cross beams; 5. Tunnel locking anchor rods; 6. Tunnel secondary lining; 7. Tunnel surrounding rock; 8. Tunnel primary support steel frame; 9. Tunnel pile foundation; 10. Spanning structures. DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0037] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0038] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0039] See also Figure 1 to Figure 3 It is a bridge-lining combined structure with tunnel crossing function, including a bridge deck 1, with supporting longitudinal beams 2 fixed on both sides of the width direction below the bridge deck 1, and a plurality of transversely arranged supporting crossbeams 3 fixed on the lower end surface of the bridge deck 1. The supporting crossbeams 3 are evenly spaced, and the two ends of the supporting crossbeams 3 pass through the supporting longitudinal beams 2 and are fixedly connected with the tunnel primary support steel frame 8 in the tunnel as a whole. The tunnel primary support steel frame 8 is close to the inner wall of the tunnel to play a supporting role, and the inner side of the tunnel primary support steel frame 8 is the tunnel secondary lining 6. The outer side of the tunnel is the tunnel surrounding rock. Below the bridge deck 1 is the spanned structure 10, and both sides of the bridge deck 1 extend to the tunnel surrounding rock.

[0040] The end support beams 4 are located at both ends of the space to be spanned in the tunnel. They are concrete structural beams that are consolidated into one with the support longitudinal beams 2 and are used to transfer loads laterally at the ends.

[0041] The tunnel pile foundation 9 in the tunnel is arranged at the intersection of the end support cross beam 4 and the support longitudinal beam 2, and there are four piles in total, which are used to support the entire span structure. The tunnel pile foundation 9 adopts a reinforced concrete cast-in-place pile with a circular cross section.

[0042] The supporting longitudinal beam 2 spans the space to be spanned in the tunnel, that is, spans the spanned structure 10. The supporting longitudinal beam 2 is a reinforced concrete beam, which can be a rectangular section or a box section. It is located at the foot of the tunnel secondary lining 6 and serves as the main force-bearing structure of the bridge span. The transverse steel bars of the tunnel secondary lining 6 are anchored into the supporting longitudinal beam through the tunnel foot anchor rod 5, so that the supporting longitudinal beam 2 is connected to the upper tunnel secondary lining 6 as a whole. The steel bar anchorage length meets the requirements of relevant specifications.

[0043] The supporting longitudinal beam 2 extends a certain length into the tunnel surrounding rock at the bottom of the tunnel on both sides, so that the supporting longitudinal beam 2 becomes a continuous beam structure, and the beams within the side spans at both ends become elastic foundation beams, which can share the load of the tunnel pile foundation.

[0044] The supporting cross beam 3 is located between the two supporting longitudinal beams 2 and is used to distribute the bridge deck load. The supporting cross beam 3 is a steel structure beam and can be made of H-shaped steel or I-shaped steel.

[0045] Both ends of the support beam 3 pass through the support longitudinal beam 2 and are welded to form a whole with the tunnel primary support steel frame 8. Welding is carried out by means of weld connection, bolt connection, etc.

[0046] The bridge deck 1 is located on the supporting longitudinal beams 2 and the supporting cross beams 3, and is used to directly bear the live load. It is a reinforced concrete slab.

[0047] All exposed steel structure components must be treated with anti-corrosion.

[0048] Specific embodiments:

[0049] The supporting longitudinal beam 2 spans the spanned structure 10 in the tunnel, with a span of 16m. The supporting longitudinal beam 2 is a C40 reinforced concrete beam with a rectangular cross section and a cross-sectional size of 3000mm×2000mm. The supporting longitudinal beam 2 is set at the foot of the tunnel secondary lining 6 as the main force-bearing structure of the bridge span. The transverse steel bars of the tunnel secondary lining 6 are anchored into the supporting longitudinal beam 2, so that the supporting longitudinal beam 2 is connected to the tunnel secondary lining 6 above as a whole. The steel bar anchorage length is 30D (D is the steel bar diameter).

[0050] The supporting longitudinal beam 2 extends 0.6B into the rock mass at the bottom of the tunnel on both sides, where B is a span of 16m, making the supporting longitudinal beam 2 a continuous beam structure, and the beams within the side spans at both ends become elastic foundation beams, which can share the load of the tunnel pile foundation.

[0051] The end support beam 4 is a C40 concrete structural beam with a rectangular cross section and a cross-sectional size of 2000mm×2000mm. The end support beam 4 is consolidated into one with the supporting longitudinal beam 2 and is used to transfer the end load laterally.

[0052] The tunnel pile foundation 9 adopts a circular cross-section C30 reinforced concrete cast-in-place pile with a diameter of 1.5m.

[0053] The supporting cross beam 3 is a steel structure beam made of HW400 steel. The spacing of the supporting cross beam 3 corresponds to the spacing of the tunnel primary support steel frame 8. The spacing of the tunnel primary support steel frame 8 is 1m, and the spacing of the supporting cross beam 3 is 2m.

[0054] The two ends of the supporting beam 3 are welded to the tunnel primary support steel frame 8 by using fillet welds.

[0055] The bridge deck is C40 reinforced concrete slab with a thickness of 300mm.

[0056] The specific construction method created by the present invention is divided into two types:

[0057] The first method is to build the tunnel first, and then build the space under the tunnel after the tunnel.

[0058] In the first step, the primary support steel frame 8 and the secondary lining 6 of the tunnel are constructed according to the traditional tunnel construction method, steel bars and steel section joints are reserved at the arch feet of the primary support steel frame 8 and the secondary lining 6 of the tunnel, and tunnel locking anchor rods 5 for fixing are prepared.

[0059] The second step is to construct the tunnel pile foundation 9 in the tunnel. The tunnel pile foundation 9 is generally constructed by manual digging. After the manual digging, the steel bars of the tunnel pile foundation 9 are placed, and then concrete is poured into the hole to form four tunnel pile foundations 9 for support.

[0060] The third step is to excavate the space required for the bridge span structure in the tunnel, including the space for the supporting longitudinal beams 2 to extend into the tunnels at both ends, and the space for the end supporting cross beams 4. The position of the end supporting cross beams 4 is located between the pouring spaces of the two supporting longitudinal beams 2 at the position of the tunnel pile foundation 9.

[0061] The fourth step is to install the steel structure of the supporting beam 3 so that it is welded to the reserved steel joint of the arch foot of the tunnel primary support steel frame 8 as a whole.

[0062] The fifth step is to install the steel bars of the supporting longitudinal beam 2 in the space of the excavated supporting longitudinal beam 2, so that the steel bars of the supporting longitudinal beam 2 and the steel bar joints reserved at the arch foot of the tunnel secondary lining 6 are fixed as a whole through the tunnel locking anchor rod 5, and install the steel bars of the end supporting cross beam 4 in the space of the end supporting cross beam 4, so that the two ends of the steel bars of the end supporting cross beam 4 are respectively welded to the steel bars of the supporting longitudinal beam 2 as a whole, and concrete is poured in the space of the supporting longitudinal beam 2 and the space of the end supporting cross beam 4 respectively to form a reinforced concrete beam.

[0063] In the sixth step, a space for the bridge deck 1 is dug out above the supporting longitudinal beam 2 and the supporting cross beam 3, and concrete is poured in the space to form the bridge deck 1.

[0064] The seventh step is to construct the span space under the tunnel by directly excavating the surrounding rock to the edge of the span structure without taking other support measures.

[0065] The second downward crossing space has been formed.

[0066] The first step is to construct the tunnel primary support steel frame 8 and the tunnel secondary lining 6 of the tunnel according to the traditional tunnel construction method, reserve steel bars and steel joints at the arch feet of the tunnel primary support steel frame 8 and the tunnel secondary lining 6, and prepare the tunnel locking anchor rods 5.

[0067] The second step is to construct the tunnel pile foundation 9 in the tunnel. The tunnel pile foundation 9 is generally constructed by manual digging. After the manual digging, the steel bars of the tunnel pile foundation 9 are placed, and then concrete is poured into the hole to form four tunnel pile foundations 9 for support.

[0068] The third step is to first excavate the space of the supporting longitudinal beam 2 on a single side and quickly pour concrete to form the supporting longitudinal beam 2. The steel bars of the supporting longitudinal beam 2 are placed in the space of the supporting longitudinal beam 2. At the same time, the supporting cross beam 3 and the steel joint are pre-embedded in the supporting longitudinal beam 2.

[0069] The fourth step is to excavate the space of the supporting longitudinal beam on the other side and quickly pour concrete to form the supporting longitudinal beam 2. The steel bars of the supporting longitudinal beam 2 are placed in the space of the supporting longitudinal beam 2. At the same time, the supporting cross beam 3 and the steel joint are pre-buried in the supporting longitudinal beam 2. The steel bars of the end supporting cross beam 4 are installed in the space of the end supporting cross beam 4, and concrete is poured in the space of the end supporting cross beam 4 to form a reinforced concrete beam.

[0070] The fifth step is to construct the steel structure of the remaining supporting cross beam 3 in the middle part between the two supporting longitudinal beams 2, and weld it to the steel joint of the supporting cross beam 3 embedded in the supporting longitudinal beam 2 to form a whole;

[0071] In the sixth step, a space for the bridge deck 1 is dug out above the supporting longitudinal beam 2 and the supporting cross beam 3, and concrete is poured in the space to form the bridge deck 1.

[0072] The present invention combines the traditional bridge structure set in the tunnel with the lining structure of the tunnel to form a lining structure with a bridge span function, or a bridge span structure with a lining function. Such a combined structure has two technical features: 1) The main force-bearing structure supporting longitudinal beam 2 of the bridge span system is connected to the secondary lining 6 of the tunnel as a whole, thereby increasing the rigidity of the supporting longitudinal beam 2, so that the supporting longitudinal beam 2 does not need a large cross-section and reinforcement to withstand the large surrounding rock load transmitted by the tunnel surrounding rock. 2) The supporting crossbeam 3 of the steel structure is welded to the tunnel primary support steel frame 8 as a whole, and the entire bridge span structure can be locked on the surrounding rock with the help of the locking foot anchor rod and the system anchor rod on the secondary lining 6 of the tunnel, so that the bridge span structure becomes a semi-elastic foundation beam, thereby suppressing the deformation of the supporting longitudinal beam 2 and improving the force of the bridge span structure. Since the primary support lining and the secondary lining of the tunnel are generally separated, the primary support generally adopts a shotcrete + steel frame + anchor rod structure and is close to the surrounding rock; while the secondary lining generally adopts a reinforced concrete structure and is separated from the primary support structure. Therefore, the above technical points are, on the one hand, to combine the bridge span structure with the tunnel secondary lining 6, and on the other hand, to combine the bridge span structure with the tunnel primary support steel frame 8 through the supporting crossbeam 3 of the steel structure.

[0073] The present invention also optimizes the stress form of the supporting longitudinal beam 2 of the main load-bearing member in the bridge span structure. By extending the supporting longitudinal beam 2 to both ends, elastic foundation beams on both sides are formed to bear the load together with the tunnel pile foundation, which greatly reduces the load on the pile foundation and improves the foundation stress. On the other hand, the internal force of the beam is also reduced (the beam is optimized from a simply supported beam to a continuous beam with elastic support on the side span, and the bending moment is greatly reduced).

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A bridge-lining combined structure with tunnel spanning function, characterized by: The invention comprises a bridge deck (1), wherein supporting longitudinal beams (2) are respectively fixed on both sides of the width direction below the bridge deck (1), and a plurality of transversely arranged supporting cross beams (3) are fixed on the lower end surface of the bridge deck (1), wherein the supporting cross beams (3) are evenly spaced, and the two ends of the supporting cross beams (3) respectively pass through the supporting longitudinal beams (2) and are fixedly connected to the tunnel primary support steel frame (8) in the tunnel as a whole, wherein the inner side of the tunnel primary support steel frame (8) is the tunnel secondary lining (6), and the transverse steel bars of the tunnel secondary lining (6) are anchored in the supporting longitudinal beams (2), and the end supporting cross beams (4) are located at the two ends of the space to be spanned in the tunnel, and the end supporting cross beams (4) and the supporting longitudinal beams (2) are fixedly connected as a whole, and the tunnel pile foundation (9) in the tunnel is arranged at the intersection of the end supporting cross beams (4) and the supporting longitudinal beams (2).

2. The bridge-lining combined structure with tunnel spanning function according to claim 1 is characterized in that: The supporting longitudinal beam (2) extends to the non-bridge span section in the tunnel on both sides and is supported on the surrounding rock.

3. The bridge-lining combined structure with tunnel spanning function according to claim 2 is characterized in that: The length of the supporting longitudinal beam (2) extending into the rock mass at the bottom of the tunnel on both sides is 0.6B, where B is the span of the space to be crossed.

4. The bridge-lining combined structure with tunnel spanning function according to claim 1 is characterized in that: The spacing of the supporting cross beams (3) corresponds to the spacing of the tunnel primary support steel frames (8), and the spacing of the supporting cross beams (3) is an integer multiple of the spacing of the tunnel primary support steel frames (8).

5. A construction method for a bridge-lining combined structure with a tunnel spanning function, characterized in that The following steps are involved: S1: constructing the tunnel primary support steel frame (8) and the tunnel secondary lining (6) of the tunnel according to the conventional tunnel construction method, and reserving steel bars and steel section joints at the arch feet of the tunnel primary support steel frame (8) and the tunnel secondary lining (6); S2: Tunnel pile foundation in the construction tunnel; S3: construction support longitudinal beam (2) and support transverse beam (3); S4: digging out a space for the bridge deck (1) above the supporting longitudinal beam (2) and the supporting cross beam (3), and pouring concrete in the space to form the bridge deck (1); wherein: when the space to be crossed under the tunnel is constructed after the tunnel, the specific steps of S3 are: Excavating the space required for the bridge span structure in the tunnel, including the space for the supporting longitudinal beam (2) to extend into the tunnels at both ends, and also including the space for the end supporting cross beam (4), the position of the end supporting cross beam (4) being located between the pouring spaces of the two supporting longitudinal beams (2) at the position of the tunnel pile foundation (9); installing the steel structure of the supporting cross beam (3) so that it is welded to the reserved steel joint of the arch foot of the tunnel primary support steel frame (8) as a whole; The steel bars of the supporting longitudinal beam (2) are installed in the space of the excavated supporting longitudinal beam (2), so that the steel bars of the supporting longitudinal beam (2) and the steel bar joints reserved at the arch foot of the tunnel secondary lining (6) are fixedly connected as a whole through the tunnel foot locking anchor rod (5), and the steel bars of the end supporting cross beam (4) are installed in the space of the end supporting cross beam (4), so that the two ends of the steel bars of the end supporting cross beam (4) are respectively welded to the steel bars of the supporting longitudinal beam (2) as a whole, and concrete is poured in the space of the supporting longitudinal beam (2) and the space of the end supporting cross beam (4) to form a reinforced concrete beam; when the spanning space has been formed, the specific steps of S3 are: First, a space for the supporting longitudinal beam (2) on a single side is excavated and concrete is quickly poured to form the supporting longitudinal beam (2), steel bars of the supporting longitudinal beam (2) are placed in the space for the supporting longitudinal beam (2), and at the same time, a supporting cross beam (3) and a steel joint are pre-buried in the supporting longitudinal beam (2); Then, a space for the supporting longitudinal beam (2) on the other side is excavated and concrete is quickly poured to form the supporting longitudinal beam (2), wherein the steel bars of the supporting longitudinal beam (2) are placed in the space for the supporting longitudinal beam (2), and the supporting cross beam (3) and the steel joint are pre-buried in the supporting longitudinal beam (2); the steel bars of the end supporting cross beam (4) are installed in the space for the end supporting cross beam (4), and concrete is poured in the space for the end supporting cross beam (4) to form a reinforced concrete beam; The steel structure of the remaining supporting cross beam (3) in the middle part between the two supporting longitudinal beams (2) is welded to form a whole with the steel joint of the supporting cross beam (3) embedded in the supporting longitudinal beam (2).

6. The construction method of a bridge-lining combined structure with tunnel spanning function according to claim 5 is characterized in that: The tunnel pile foundation (9) is formed by a manual hole digging process. After the holes are dug manually, the steel bars of the tunnel pile foundation (9) are placed in the holes. Then, concrete is poured into the holes to form four tunnel pile foundations (9) for support.

7. The construction method of a bridge-lining combined structure with tunnel spanning function according to claim 5, characterized in that: When the space to be crossed under the tunnel is constructed after the tunnel is built, step S5 is also included: constructing the crossing space under the tunnel, directly excavating the surrounding rock to the edge of the bridge span structure, without taking other support measures.

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