CN216786789U - Multi-span simply supported prestressed bridge span in tunnel - Google Patents

Abstract

The utility model relates to a multi-span simply supported prestressed bridge span in a tunnel, wherein a tunnel inverted arch is loaded above a bridge girder, and a post-cast force transfer layer is arranged between the bridge girder and the tunnel inverted arch; supporting cushions are arranged below two ends of the bridge main beam, a capping beam is arranged below the supporting cushions, and the bottom of the capping beam is supported by a plurality of hole piles supported on bedrock; the bottom surface system conversion layer is arranged below the bridge span part of the bridge girder, the bottom plate cross support layer is arranged below the bottom surface system conversion layer, and the soft foundation is arranged below the bottom plate cross support layer. The method solves the problem of tunnel construction under the condition of a weak foundation, and the construction process does not need to adopt large-scale mechanical construction and a multi-pile-foundation construction scheme on the weak foundation, thereby greatly reducing the construction difficulty and the construction cost.

Description

Multi-span simply supported prestressed bridge span in tunnel

Technical Field

The utility model relates to the technical field of road building construction, in particular to a multi-span simply supported prestressed bridge span in a tunnel.

Background

The weak foundation is a bad foundation, has the defects of low strength, high compressibility and the like, brings the consequences of poor stability of the foundation, deformation of the foundation, settlement of the foundation and the like, and in order to meet the design requirements, the construction on the weak foundation has the following method: 1. arranging a reinforced concrete pile foundation or a steel pipe pile below the building, wherein the lower end of the pile foundation directly props against a foundation stratum, and the building is sufficiently supported; 2. excavating soft foundation soil, and replacing the soft foundation soil with harder sandy soil from other places to obtain a foundation with higher strength; 3. adding curing agents such as cement and the like into the deep layer of the soft foundation and stirring to reform the soft foundation into foundation soil with certain strength; 4. and (4) processing the foundation by using a tamping machine or a rolling machine.

The tunnel belongs to long and narrow structural style, and when there is weak foundation, the tunnel can appear lasting settlement deformation, bears great load. The soft foundation problem of the tunnel needs to solve the safety during construction and the reliability during operation. Due to the limitation of construction space, the soft foundation treatment of the tunnel can only adopt small-sized equipment, usually can only adopt miniature steel pipe piles, jet grouting piles and bridge span structures. The bearing capacity of the single pile of the miniature steel pipe pile is small, and the arrangement is small and dense, so the processing cost is high. The jet grouting pile has poor geological adaptability, is not practical for geological conditions such as boulders, soft plastic clay and the like, and has large jet grouting disturbance and high safety risk. Generally speaking, the bridge span structure cost is low, and durability and reliability superiority are outstanding, because the long-term load in weak foundation section tunnel is huge, the bridge span generally can only accomplish the biggest span of 15 meters in the tunnel, has restricted the application range of bridge span structure, and little bridge span structure need set up more basis, has brought the difficulty for the construction, because there is safe risk in the foundation excavation, and construction safety has reduced. The prestressed bridge span structure is applied in a tunnel without pertinence, and the main reason is that a closed space is formed in the tunnel, and a deformation space required when prestress is applied cannot be provided. Bridge span structure mainly adopts cast-in-place concrete structure in the tunnel at present, adopts prestressed concrete bridge span structure increase span in the tunnel, reduces the risk that bearing structure construction brought, reduces the engineering cost that weak basis was dealt with in the tunnel, and is very urgent.

Disclosure of Invention

The utility model aims to provide a multi-span simply-supported prestressed bridge span in a tunnel, which solves the problem of tunnel construction under the condition of a weak foundation in the prior art, does not need to adopt large-scale mechanical construction in the construction process, does not need to adopt excessive pile foundation construction schemes on the weak foundation, greatly reduces the construction difficulty and reduces the construction cost.

In order to achieve the purpose, the technical scheme of the utility model is as follows:

a multi-span simply supported prestressed bridge span in a tunnel is characterized in that a tunnel inverted arch is loaded above a bridge girder, and a post-cast force transfer layer is arranged between the bridge girder and the tunnel inverted arch; supporting pads are arranged below two ends of the main bridge beam, a cover beam is arranged below the supporting pads, and the bottom of the cover beam is supported by a plurality of hole piles supported on bedrock; the lower part of the bridge span part of the bridge girder is a bottom system conversion layer, the lower part of the bottom system conversion layer is a bottom plate cross support layer, and the lower part of the bottom plate cross support layer is a soft foundation.

Two side surfaces of the bridge girder are side system conversion layers, and the outer side surfaces of the side system conversion layers are connected with side primary supports.

The middle of the bridge girder is divided into a left span and a right span along the inside of the center line of the tunnel, and a girder intermediate system conversion layer is arranged between the two spans.

And each span of the bridge girder is provided with a bottom system conversion operation space.

The bottom plate transverse supporting layer is a bottom supporting system formed by steel plates and section steel concrete.

And two ends of the bridge girder are provided with prestress applying operation spaces.

The supporting pad is made of felt.

The construction method of the multi-span simply supported prestressed bridge span in the tunnel comprises the following steps:

(1) casting a bridge span structure in situ;

(1-1) carrying out roof truss-by-roof truss excavation on the tunnel, adding a steel frame locking anchor rod in the excavation process, excavating the space of a bridge span structure, and constructing a bottom plate cross support layer in time;

(1-2) constructing a pile foundation of the hole pile at a preset position in a manual hole digging mode, wherein the steel pipe dado is required to follow all the time in the hole digging process, and the pile foundation is supported on bedrock; then constructing a cover beam of the bridge span structure on the hole pile, and arranging a felt on the top of the cover beam as a beam body supporting surface;

(1-3) welding the bottom plate cross support layer with the side primary supports on the two sides to form a whole;

(1-4) paving a sand layer on the bottom plate cross brace layer to serve as a system conversion layer, and placing a steel plate on the top of the sand layer;

(1-5) forming a lateral system conversion layer between the lateral primary supports and the conventional support templates on the primary support sides close to the two ends of the tunnel;

(1-6) forming a lateral mold of the beam intermediate system conversion layer by adopting a conventional supporting template in the bottom system conversion space, and forming the beam intermediate system conversion layer by adopting steel plates, steel bars and the like at the positions between beams;

(1-7) binding reinforcing steel bars and reserving prestressed pipelines on the left and right side beam bodies of the bridge girder in sequence, respectively pouring and then maintaining, and forming a bridge by bridge span joints;

(2) switching a prestress application system;

(2-1) removing the supporting templates and steel bars of the lateral system transfer layer and the beam intermediate system transfer layer to form free spaces between the lateral surfaces and the beams;

(2-2) adopting a manual operation method, adopting high-pressure water to impact a sand layer in the bottom system conversion layer, and timely removing gravel to enable the bottom system conversion layer to form a free space; then checking the free space cleaning conditions of the bottom, the side faces, the beam spaces and the end heads, and supplementing and cleaning the omitted places;

(3) application of prestressing force

(3-1) applying operation spaces by utilizing the prestress at two ends of the bridge span structure, applying the prestress according to design, paying attention to the application condition of the prestress constantly in the application process, checking the deformation and cracking conditions of the beam body in time, stopping applying the prestress if the deformation and cracking conditions are abnormal, applying a head sealing section, and wrapping the prestressed anchor head in concrete;

(4) conversion of a permanent bridge span structure;

(4-1) adopting high-strength cement mortar, and grouting and pouring free spaces formed by the side system conversion layer and the bottom system conversion layer in a pressure pouring mode to ensure that the beam body is tightly connected with the bottom support system and the side primary support;

and (4-2) pumping concrete into the prestress application operation space for filling, wherein a gap is formed between the pumped concrete and the beam body sealing anchor, and the gap is filled by adopting flocculent asphalt.

And (4-3) filling the prestressed construction spaces at the two ends of the abutment with concrete to form an inverted arch foundation.

And (4-4) finally, sequentially constructing a post-cast force transfer layer and a tunnel secondary lining above the bridge girder.

The structural principle of the utility model is as follows:

the bottom plate cross bracing layer of the multi-span simply-supported prestressed bridge span provides a foundation plane located above the surface of a soft foundation, and two ends of the bottom plate cross bracing layer are fixed on a primary support steel frame, so that a temporary safety space is provided for bridge span structure construction.

A bottom system conversion layer is formed between the bridge girder and the cross brace layer and is poured by back mud jacking, so that the formed system conversion layer, the bridge girder above and the cross brace layer below are tightly attached without gaps, the weight of the bridge girder above can be completely and uniformly transferred to the cross brace layer, finally the bearing capacity is dispersed into the bottom foundation and surrounding rocks on two sides, and the settlement caused by the uneven pressure generated on the weak foundation is avoided.

A side system conversion layer is formed between the bridge girder and the primary supports on the two sides, and on one hand, the side system conversion layer provides flat surface contact for the two sides of the bridge girder, so that the stability of the bridge girder is better; on the other hand, the side system conversion layer is poured by back grouting, the bridge girder is tightly and fixedly connected with the primary supports on the two sides, and part of pressure of the bridge girder is transferred to surrounding rocks on the two sides through the side system conversion layer, so that excessive pressure on a weak foundation is further reduced.

The function of the beam intermediate system conversion layer is as follows: the left part and the right part of the bridge girder are separately poured, prestress is separately applied, and the beam intermediate system conversion layer provides deformation space for the left part and the right part; the construction is more convenient.

The utility model has the advantages that:

1. the utility model realizes the connection between the bottom surface of the main bridge and the cross supporting layer and the weak foundation through the bottom surface system conversion layer, and provides supporting force for the pouring of the prestressed bridge span structure, thereby avoiding overlarge deformation in the bridge pouring process and ensuring the bridging of the bridge span structure.

2. According to the utility model, through the arrangement of the bottom and side conversion layers, the free deformation of the bridge span structure under the action of the prestress during the construction prestress is ensured, the effective application of the prestress is ensured, and the generation of constraint stress is avoided.

3. The bottom system conversion layer, the side system conversion layer and the beam intermediate system conversion layer which are finally formed by the method are subjected to grouting after the prestressed construction of the bridge girder, so that the bottom system conversion layer, the side system conversion layer and the beam intermediate system conversion layer are completely matched and fixed without gaps with the prestressed bridge girder, the prestressed bridge girder is completely attached to and not separated from the surrounding structure, and the method has good effects in the aspects of firmness, shock absorption and the like.

Description of the drawings:

FIG. 1 is a schematic longitudinal sectional view of the present invention;

FIG. 2 is a schematic cross-sectional structure of the present invention;

the serial numbers and component names in the figures are: 1. a tunnel inverted arch; 2. post-pouring a force transfer layer; 3. a bridge girder; 4. a bottom surface system conversion layer; 5. a floor cross-brace layer; 6. a support pad; 7. a capping beam; 8. pile holes; 9. invert bed rock; 10. a beam intermediate transfer layer; 11. a side system conversion layer; 12. and (5) primary supporting on the side surface.

Detailed Description

Example 1

A multi-span simply supported prestressed bridge span in a tunnel is characterized in that a tunnel inverted arch 1 is loaded above a bridge girder 3, and a post-cast force transfer layer 2 is arranged between the bridge girder 3 and the tunnel inverted arch 1; supporting pads 6 are arranged below two ends of the bridge main beam 3, a cover beam 7 is arranged below the supporting pads 6, and the bottom of the cover beam 7 is supported by a plurality of hole piles 8 supported on bedrock; the lower part of the bridge span part of the bridge girder 3 is a bottom system conversion layer 4, the lower part of the bottom system conversion layer 4 is a bottom plate cross bracing layer 5, and the lower part of the bottom plate cross bracing layer 5 is a soft foundation.

Two side surfaces of the bridge girder 3 are side system conversion layers 11, and the outer side surfaces of the side system conversion layers 11 are connected with side primary supports 12.

The middle of the bridge main beam 3 is divided into a left span and a right span along the center line of the tunnel, and a beam intermediate system conversion layer 10 is arranged between the two spans.

And a bottom system conversion operation space is arranged at each span of the bridge girder 3.

The bottom plate cross bracing layer 5 is a bottom bracing system formed by steel plates and steel reinforced concrete.

And prestress applying operation spaces are arranged at two ends of the bridge girder 3.

The supporting pad 6 is made of felt.

Claims (7)

1. A multi-span simply supported prestressed bridge span in a tunnel is characterized in that a tunnel inverted arch (1) is loaded above a bridge girder (3), and a post-cast force transfer layer (2) is arranged between the bridge girder (3) and the tunnel inverted arch (1); supporting pads (6) are arranged below two ends of the bridge main beam (3), a cover beam (7) is arranged below the supporting pads (6), and the bottom of the cover beam (7) is supported by a plurality of hole piles (8) supported on bedrock; a bottom system conversion layer (4) is arranged below a bridge span part of the bridge girder (3), a bottom plate cross support layer (5) is arranged below the bottom system conversion layer (4), and a soft foundation is arranged below the bottom plate cross support layer (5).

2. The multi-span simple-supported prestressed bridge span in a tunnel according to claim 1, wherein two lateral surfaces of the main bridge (3) are lateral system conversion layers (11), and the lateral surfaces of the lateral system conversion layers (11) are connected with lateral primary supports (12).

3. The multi-span simple-supported prestressed bridge span in a tunnel according to claim 1, wherein the middle of the main bridge (3) is divided into a left span and a right span along the center line of the tunnel, and a bridge body system conversion layer (10) is arranged between the two spans.

4. The multi-span simple-supported prestressed bridge span in a tunnel according to claim 1, wherein: and each span of the bridge girder (3) is provided with a bottom system conversion operation space.

5. The multi-span simple-supported prestressed bridge span in a tunnel according to claim 1, wherein: the bottom plate cross bracing layer (5) is a bottom bracing system formed by steel plates and steel reinforced concrete.

6. The multi-span simple-supported prestressed bridge span in a tunnel according to claim 1, wherein: and two ends of the bridge girder (3) are provided with prestress applying operation spaces.

7. The multi-span simple-supported prestressed bridge span in a tunnel according to claim 1, wherein: the supporting pad (6) is made of felt.

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