Flood-resistant anchorage structure and construction method of low T-beam flood bridge

Abstract

The invention discloses a flood-resistant anchoring structure and construction method of a low T-beam flooded bridge, including structures such as bridge piers, cap beams, manufacturing, low T-beams, wet joints, pavement layers, sidewalks and railings. An anchor rod connected by anchoring is mainly provided between the wet joint and the cap beam. The anchor rod is composed of an upper anchor rod pre-buried in the wet joint, a lower anchor rod pre-buried in the cap beam, and a spring respectively connected to the upper and lower anchor rods, and the spring is located between the bottom of the wet joint and the top of the cap beam. The structure can improve the flood-resistant horizontal dynamic water pressure of the bridge, increase the stability of the bridge deck system, improve the durability of the bridge, etc. The calculation method provided by the invention has clear principles, is practical and easy to implement, and can be used as a design basis and construction guidance for the flood-resistant anchoring structure of the low T-beam flooded bridge, and improves safety and quality performance. Therefore, the invention has structural characteristics such as simple structure, convenient construction, low cost, safety and reliability, and has high economic and social benefits in combination with corresponding construction methods.

Description

Technical Field

[0001] The invention relates to the field of bridge construction, and in particular to a flood-resistant anchoring structure of a low T-beam flooded bridge and a construction method. Background Art

[0002] A large number of flooded bridges are built on rural roads, tourist roads and other roads with low traffic volume. The bridge elevation is designed according to the normal water level. During floods, water is allowed to intermittently overflow the bridge bearings or bridge decks. The bridge railings can be transparent, foldable or retractable to reduce flood resistance. The bridge deck of a flooded bridge is generally a small and medium span of 8m to 20m. A hollow slab structure is used for 8m to 16m, and a T-beam structure is used for spans above 16m. In order to increase the flood resistance stability of the bridge deck structure, anchor rods are often used to anchor the bridge deck to the cap beam. Hollow slab bridge decks have defects such as web cracks and concrete spalling at hinge joints, which affect their use function. At the same time, the anchoring effect of hollow slab bridge decks is poor; the T-beam structure is high, the retaining area is large, and the T-beam end steel bars are densely distributed, making it difficult to arrange anchor rods. In recent years, short T-beam structures have been widely used to replace hollow slabs and traditional T-beam structures. This short T-beam structure is particularly suitable for flooded bridges. Therefore, short T-beam flooded bridges also urgently need to develop suitable flood-resistant anchoring structures. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a low T-beam flood bridge anti-flood anchoring structure and construction method which is simple in structure, convenient in construction, low in cost, safe and reliable.

[0004] The technical problem of the present invention is achieved through the following technical solutions:

[0005] A flood-resistant anchoring structure for a low T-beam flood bridge, comprising a plurality of supports installed on a cap beam of a bridge pier and a plurality of prefabricated low T-beams arranged on the plurality of supports, each low T-beam being provided with a plurality of cross beams, and mutually connected wet joints being provided between the plurality of cross beams of the plurality of low T-beams, a bridge deck pavement layer being cast on the plurality of low T-beams, and sidewalks and railings being installed, an anchor rod being provided between each of the wet joints and the cap beam for anchoring connection, the anchor rod being composed of an upper anchor rod pre-buried in the wet joint, a lower anchor rod pre-buried in the cap beam, and springs respectively connecting the upper and lower anchor rods, and the spring being located between the bottom of the wet joint and the top of the cap beam.

[0006] The short T-beam, wet joint, anchor rod, bridge deck pavement, sidewalk and railing are collectively referred to as the bridge deck system. When the flood just overflows the highest part of the sidewalk, the bridge deck system is subject to the maximum vertical buoyancy, which is simplified to the uniformly distributed load q sy At this time, the horizontal bridge is subjected to horizontal dynamic water pressure F sx It is also the largest; assuming that the bridge deck is under the action of its own weight, vertical buoyancy and horizontal hydrodynamic pressure, a span of short T-beam rotates slightly clockwise with the support center of the farthest short T-beam as the fulcrum Angle, according to the principle of force balance and elasticity theory, the following calculation formula is obtained:

[0007] Formula 1:

[0008] The calculation formula for the bridge deck system and anchor force is as follows:

[0009]

[0010]

[0011] Formula 2:

[0012] The stress and diameter of the upper and lower anchor rods are calculated as follows:

[0013]

[0014] Formula 3:

[0015] The compression of the compression spring under the bridge deck load is not less than the maximum compression of the support. , and the spring does not produce plastic deformation when it is pulled under the horizontal hydrodynamic pressure of the flood. The relevant parameters of the spring are calculated as follows:

[0016] When the spring is compressed

[0017]

[0018] ,

[0019] When the spring is stretched

[0020]

[0021] When the spring is compressed Substituting into the above formula needs to satisfy

[0022]

[0023] In formula 2 As in formula 3 When the values ​​are close, the diameter of the spring wire is the same as the diameter of the upper and lower anchor rods. , if the difference between the two is large, take the value according to the calculated result;

[0024] The symbols in Formula 1, Formula 2 and Formula 3 are defined as:

[0025] ——respectively the length of one span of the bridge and the full width of the bridge deck, ;

[0026] ——respectively, the spacing of anchors buried in wet joints, the horizontal distance from the center of the first anchor on the water-facing side to the center of the support of the short T-beam side beam, the horizontal distance from the center of the support of the short T-beam side beam on the water-facing side to the water-facing side, and the width of the block in the transverse direction of the bridge. ;

[0027] ——respectively the diameter of the anchor rod, the middle diameter of the spring, and the diameter of the spring wire material, ;

[0028] ——respectively the spring pitch, clearance, elongation under maximum load, and effective number of turns, , , , dimensionless;

[0029] ——Water blocking height of bridge superstructure, ;

[0030] ——respectively, the height of the block, the height of the support, the height of the water-facing surface of the bridge deck, the total length of the anchor rod, the length of the upper anchor rod buried in the wet joint, the height of the spring from the bottom of the wet joint to the top of the cap beam, and the length of the lower anchor rod buried in the cap beam. ;

[0031] ——are the cross-sectional area of ​​the anchor rod and the horizontal cross-sectional area of ​​the support, ;

[0032] ——The number of anchor rods for the wet joint and a cap beam on one side of a span low T beam. There are n anchor rods at each end of a span low T beam, numbered C 1 , C 2 , C 3 , ..., C i , ..., C n ;

[0033] ——The rotation angle of a span bridge deck system with the farthest short T-beam support as the fulcrum when subjected to horizontal hydrodynamic pressure, ;

[0034] ——are the buoyancy and horizontal water dynamic pressure on the bridge deck system, ;

[0035] ——respectively, the horizontal hydrodynamic pressure, the horizontal reaction force of the cap beam end block, and the horizontal friction resistance of the support, ;

[0036] ——are the elastic modulus of the support, the cross-sectional area of ​​the support, and the pressure of the support, respectively. ;

[0037] ——Respectively The tension of the anchor rod, ;

[0038] ——are the shear force and moment of the anchor rod. The main force of the anchor rod is tension, and the shear force and moment have little effect. In order to simplify the calculation, it is assumed that the shear force and moment of each anchor rod are the same. At the same time, the influence of the transverse slope of the bridge deck is ignored when calculating the moment of the support bottom of the first short T-beam on the water-facing surface. ;

[0039] ——One span at both ends of the bridge deck The total moment on the anchor rod is: ;

[0040] ——The weight of water, ;

[0041] ——Design flood velocity, ;

[0042] ——The acceleration due to gravity is equal to 9.81, ;

[0043] ——Friction coefficient between the bottom of the short T-beam and the support;

[0044] ——respectively the weight and volume of the bridge deck system, ;

[0045] ——respectively the bending stiffness of the block in the water-facing direction, the shear stiffness of the support, and the shear deformation modulus of the spring, ;

[0046] ——Elastic modulus of upper and lower anchor rods, ;

[0047] ——respectively are the tensile stress and allowable tensile stress of the straight segment anchor rod, ;

[0048] ——are the shear stress and allowable shear stress of the spring, ;

[0049] ——The maximum compression spring deformation under the maximum combined bridge deck load, ;

[0050] ——Maximum tensile deformation and allowable tensile deformation of the spring, .

[0051] The bridge piers and cap beams are the lower structure of the flood bridge and are reinforced concrete structures; the blocks are reinforced concrete structures and are arranged at both ends of the top of the cap beam.

[0052] The short T-beam is a prestressed concrete structure. The short T-beam is divided into two structural forms: a side beam and a middle beam. A bridge deck is composed of two side beams and multiple middle beams.

[0053] The crossbeam is a transverse connection structure of the short T-beam. There is no crossbeam on the outside of the side beam, but there are crossbeams on both sides of the middle beam. The crossbeam of each short T-beam has a certain width and is assembled and connected by the wet joint. Crossbeams are provided at both ends of the short T-beam, and 3 to 4 crossbeams are arranged along the span direction.

[0054] The wet joint is made of high-grade concrete, and the prefabricated short T-beam cross beams are connected in pairs to form a transverse connection of multiple short T-beams.

[0055] The anchor rod is made of ordinary steel, stainless steel or weathering steel. The anchor rod is set in the wet joint of the crossbeam of the short T-beam at the ends of a span. The upper anchor rod is welded to the steel bars in the wet joint, and the lower anchor rod is welded to the steel bars in the cap beam. The spring is a compression spring. The two ends of the spring are firmly welded to the lower end of the upper anchor rod and the upper end of the lower anchor rod. The maximum compression of the spring including the clearance is not less than the maximum compression of the support of the bridge deck system under the combined load of the vehicle. The maximum stretching of the spring must meet the maximum deformation requirement.

[0056] The bearing is a rubber bearing, and depending on the span, number of spans and connection structure of the bridge deck system, a plate rubber bearing or a polytetrafluoroethylene plate sliding plate bearing is used.

[0057] The bridge deck pavement is a reinforced concrete structure. After multiple supports, multiple prefabricated low T-beams, wet joints and anchor rods are installed, the bridge deck pavement is poured on the multiple prefabricated low T-beams, and then the sidewalks and railings are installed. Finally, the springs are firmly welded to the upper anchor rod and the lower anchor rod respectively.

[0058] A construction method for a low T-beam flood bridge anti-flood anchoring structure comprises the following steps:

[0059] Step 1: Research, testing and calculation

[0060] ① Investigate, drill and measure the geographical, geological and hydrological conditions of the project site to obtain data on engineering geology, flood design frequency and flow rate;

[0061] ② Determine the bridge span, number of spans, foundation and lower connection, and the connection structure of the low T-beam bridge deck system;

[0062] ③ Calculate the anchor rod size according to Formula 1 to Formula 3, optimize the spring parameters according to the characteristics of the rubber bearing, design the low T-beam flood bridge and propose the materials and construction process requirements;

[0063] Step 2: Foundation and substructure construction

[0064] ①Measure and stake out the bridge position and pile foundation;

[0065] ②Construct pile foundations and piers according to design requirements;

[0066] ③Construct cap beam: install cast-in-place bracket and formwork for cap beam, tie cap beam reinforcement including block reinforcement and support pad reinforcement, expose 1cm to 2cm of the upper end of the lower anchor rod from the top of the cap beam for spring welding, weld the lower anchor rod to other reinforcements firmly, pour cap beam concrete, cover with geotextile and perform concrete curing;

[0067] Step 3: Prefabrication of short T beams

[0068] ①Level the low T-beam prefabrication site and make the low T-beam prefabrication template;

[0069] ② Tie ordinary steel bars and prestressed steel bars of short T-beams;

[0070] ③ Casting of short T-beams, using automatic spraying for curing;

[0071] ④ After the short T-beam concrete reaches the specified strength, use the double-control program to tension the prestressed steel bars and promptly grout the prestressed steel bar holes;

[0072] Step 4: Bridge deck construction

[0073] ① Installation of low T beams: Prefabricated low T beams are installed by means of lifting holes through the beam bottom or by using a bridge erection machine. During the transportation, lifting and installation of low T beams, attention should be paid to maintaining the lateral stability of the beam. After erection, effective measures should be taken to strengthen temporary lateral support, and flange plates and beam wet joint steel bars should be welded in time to increase the stability and integrity of the beam.

[0074] ②Support installation: adjust the position of each low T-beam 5cm to 10cm above the support pad stone. After each low T-beam is in the correct position, place the support and drop the beam accurately;

[0075] ③ Installation of upper anchor rod: 1cm to 2cm of the lower end of the upper anchor rod is exposed at the bottom of the wet joint for spring welding, and the upper anchor rod and the wet joint steel bar are welded firmly;

[0076] ④ Casting wet joints: installing wet joint formwork, casting wet joint concrete, and curing;

[0077] ⑤ Pour the hinged concrete of the flange plate of the low T beam and ensure that the concrete is cured;

[0078] ⑥ Pouring bridge deck concrete, installing sidewalks and railings;

[0079] ⑦ Welding spring: After the bridge deck structure is completed, the spring will be welded firmly to the lower end of the upper anchor rod and the upper end of the lower anchor rod. If the reserved length of the lower end of the upper anchor rod and the upper end of the lower anchor rod is too long, it can be cut to the appropriate length and then welded. If there is misalignment, make appropriate adjustments to the upper anchor rod and the lower anchor rod before cutting the reserved length of the lower end of the upper anchor rod and the lower anchor rod.

[0080] Compared with the prior art, the present invention mainly provides a flood-resistant anchoring structure for a low T-beam flooded bridge, which has the following advantages: first, the low T-beam combines the advantages of traditional hollow slabs and T-beams, and is particularly suitable for flooded bridges. The use of anchor rods to fix the connection between the wet joint of the crossbeam and the cap beam can effectively improve the horizontal dynamic water pressure of the bridge against floods and increase the stability of the bridge deck system; second, the use of an anchor rod-spring system, that is, a compressible spring is set in the anchor rod, so that the bridge deck system is under the combined load of vehicles and the compression of the rubber bearing and the anchor rod The compression deformation is synchronized, overcoming the shortcomings of the traditional anchoring of the anti-flood structure of the bridge deck structure, avoiding damage to the anchoring point and concrete destruction, and improving the durability of the bridge; thirdly, the welding connection between the spring in the anchor rod and the upper anchor rod and the lower anchor rod is arranged after the completion of the bridge deck system, eliminating the stress of the bridge deck system in the later construction of the anchor rod-spring system, and enhancing the durability of the anchor rod-spring system; fourthly, the calculation method provided has a clear principle, is practical and easy to implement, and can be used as a design basis and construction guide for the anti-flood anchoring structure of the short T-beam flood bridge, improving the safety and quality performance. Therefore, the present invention is a low T-beam flood bridge anti-flood anchoring structure with simple structure, convenient construction, low cost, safety and reliability, which, combined with the corresponding construction method, has high economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 It is a schematic diagram of the structural elevation of the present invention.

[0082] Figure 2 for Figure 1 AA cross-section diagram.

[0083] Figure 3 This is the bridge deck force diagram.

[0084] Figure 4 Schematic diagram of the anchor rod structure.

[0085] Figure 5 This is the force diagram of the anchor rod. DETAILED DESCRIPTION

[0086] The embodiments of the present invention will be described in detail below with reference to the above-mentioned drawings.

[0087] like Figure 1~Figure 5 Indicates: 1. bridge pier, 2. cap beam, 21. block, 3. short T beam, 4. cross beam, 41. wet joint, 5. support, 6. anchor rod, 61. upper anchor rod, 62. lower anchor rod, 63. spring, 7. bridge deck pavement, 8. sidewalk, 9. railing.

[0088] Flood-resistant anchorage structure and construction method of low T-beam flood bridge, such as Figure 1 As shown, the flood-proof anchoring structure of the low T-beam flood bridge mainly includes a plurality of supports 5 installed on the cap beam 2 of the bridge pier 1 and a plurality of prefabricated low T-beams 3 arranged on the plurality of supports, each low T-beam is provided with a plurality of cross beams 4, and mutually connected wet joints 41 are provided between the plurality of cross beams 4 of the plurality of low T-beams 3, and an anchor rod 6 is provided between each wet joint and the cap beam 2 for anchoring connection, and the anchor rod is composed of three parts: an upper anchor rod 61 embedded in the wet joint 41, a lower anchor rod 62 embedded in the cap beam 2 and a spring 63 respectively connecting the upper and lower anchor rods, and the spring is located between the bottom of the wet joint 41 and the top of the cap beam 2.

[0089] After the multiple bearings 5, multiple prefabricated low T beams 3 and wet joints 41 are completed, the bridge deck pavement 7 is poured on the multiple prefabricated low T beams 3, the sidewalk 8 and the handrail 9 are installed, and finally the spring 63 between the upper anchor rod 61 and the lower anchor rod 62 is welded to complete the whole span of the bridge deck. Except for the final welding of the spring 63 between the upper anchor rod 61 and the lower anchor rod 62, the rest of the multi-span bridge deck is completed in the above order or simultaneously, and the mutual connection of each span, such as the installation of the expansion joint or the construction of the continuous structure of the bridge deck, is carried out.

[0090] The bridge piers 1 and cap beam 2 are the lower structure of the flood bridge and are reinforced concrete structures; the blocks 21 are reinforced concrete structures and are arranged at both ends of the top of the cap beam 2 to limit the slippage and slight rotation of the bridge deck system.

[0091] The short T-beam 3 is a prestressed concrete structure, which combines the advantages of traditional hollow slabs and T-beams, and is particularly suitable for flooded bridges. Short T-beam flooded bridges are generally constructed by prefabrication and installation. The short T-beam 3 is divided into two structural forms: side beams and middle beams. A bridge deck is composed of two side beams and multiple middle beams. The cross beam 4 is a transverse connection structure of the short T beam. There is no cross beam on the outside of the side beam, and there are cross beams 4 on both sides of the middle beam. The cross beams 4 of each short T beam 3 are left with a certain width and are assembled and connected by wet joints 41. Both ends of the short T beam 3 are provided with cross beams 4, and 3 to 4 cross beams are arranged along the span direction. The wet joint 41 is a high-grade concrete, and the cross beams 4 are connected in pairs to form a transverse connection of multiple short T beams 3.

[0092] The anchor rod 6 is made of ordinary steel, stainless steel or weathering steel. The anchor rod 6 is arranged in the wet joint 41 of the crossbeam 4 of the short T-beam 3 at the ends of both sides of a span. The upper anchor rod 61 is welded to the steel bars in the wet joint 41, and the lower anchor rod 62 is welded to the steel bars in the cap beam 2. The spring 63 is a compression spring. The two ends of the spring 63 are firmly welded to the lower end of the upper anchor rod 61 and the upper end of the lower anchor rod 62. The maximum compression amount of the spring 63 including the clearance is not less than the maximum compression amount of the support 5 of the bridge deck system under the combined load of the vehicle. The maximum stretching amount of the spring 63 must meet the maximum deformation requirement.

[0093] The bearing 5 is a rubber bearing. Depending on the span, number of spans and the connection structure of the bridge deck system, a plate-type rubber bearing or a polytetrafluoroethylene plate sliding plate bearing is used.

[0094] The bridge deck pavement layer 7 is a reinforced concrete structure. After the installation of multiple supports 5, multiple prefabricated low T-beams 3, wet joints 41, and anchor rods 6 is completed, the bridge deck pavement layer 7 is poured on the multiple prefabricated low T-beams 3, and then the sidewalk 8 and railings 9 are installed. Finally, the spring 63 is firmly welded to the upper anchor rod 61 and the lower anchor rod 62 respectively.

[0095] The short T-beam 3, wet joint 41, anchor rod 6, bridge deck pavement 7, sidewalk 8 and railing 9 are collectively referred to as the bridge deck system. When the flood just overflows the highest part of the sidewalk, the bridge deck system is subject to the maximum vertical buoyancy, which is simplified to the uniformly distributed load q sy At this time, the horizontal bridge is subjected to horizontal dynamic water pressure F sx It is also the largest; assuming that the bridge deck is under the action of its own weight, vertical buoyancy and horizontal hydrodynamic pressure, a span of short T-beam rotates slightly clockwise with the support center of the farthest short T-beam as the fulcrum Angle, according to the principle of force balance and elasticity theory, the following calculation formula is obtained:

[0096] Formula 1:

[0097] The calculation formula for the bridge deck system and anchor force is as follows:

[0098]

[0099]

[0100] Formula 2:

[0101] The stress and diameter of the upper and lower anchor rods are calculated as follows:

[0102]

[0103] Formula 3:

[0104] The compression of the compression spring under the bridge deck load is not less than the maximum compression of the support. , and the spring does not produce plastic deformation when it is pulled under the horizontal hydrodynamic pressure of the flood. The relevant parameters of the spring are calculated as follows:

[0105] When the spring is compressed

[0106]

[0107] ,

[0108] When the spring is stretched

[0109]

[0110] When the spring is compressed Substituting into the above formula needs to satisfy

[0111]

[0112] In formula 2 As in formula 3 When the values ​​are close, the diameter of the spring wire is the same as the diameter of the upper and lower anchor rods. , if the difference between the two is large, take the value according to the calculated result;

[0113] The symbols in Formula 1, Formula 2 and Formula 3 are defined as:

[0114] ——respectively the length of one span of the bridge and the full width of the bridge deck, ;

[0115] ——respectively the spacing of anchor rods 6 embedded in the wet joint 41, the horizontal distance from the center of the first anchor rod on the water-facing surface to the center of the support of the short T-beam side beam, the horizontal distance from the center of the support of the short T-beam side beam on the water-facing surface to the water-facing surface, and the width of the stopper 21 in the transverse direction of the bridge, ;

[0116] ——respectively the diameter of the anchor rod 6, the middle diameter of the spring, and the diameter of the spring wire material, ;

[0117] ——respectively the pitch, clearance, elongation under maximum load and effective number of turns of spring 63, , , , dimensionless;

[0118] ——Water blocking height of bridge superstructure, ;

[0119] ——respectively, the height of the stopper 21, the height of the support 5, the height of the water-facing surface of the bridge deck, the total length of the anchor rod 6, the length of the upper anchor rod 61 buried in the wet joint 41, the height of the spring 63 from the bottom of the wet joint 41 to the top of the cap beam 2, and the length of the lower anchor rod 62 buried in the cap beam 2, ;

[0120] ——are the cross-sectional area of ​​the anchor rod 6 and the horizontal cross-sectional area of ​​the support 5, ;

[0121] ——The number of anchor rods for the wet joint 41 on one side of a span of short T-beam 3 and a cap beam 2. There are n anchor rods at each end of a span of short T-beam 3, numbered C 1 , C 2 , C 3 , ..., C i , ..., C n ;

[0122] ——The rotation angle of a span bridge deck system with the farthest short T-beam support as the fulcrum when subjected to horizontal hydrodynamic pressure, ;

[0123] ——are the buoyancy and horizontal water dynamic pressure on the bridge deck system, ;

[0124] ——respectively are the horizontal hydrodynamic pressure, the horizontal reaction force of the end block 21 of the cap beam 2, and the horizontal friction resistance of the support 5, ;

[0125] ——are respectively the elastic modulus of support 5, the cross-sectional area of ​​support 5, and the pressure on the support, ;

[0126] ——Respectively Tension of anchor rod 6, ;

[0127] ——are the shear force and moment of anchor rod 6. The main force of anchor rod 6 is tension, and the shear force and moment have little effect. In order to simplify the calculation, it is assumed that the shear force and moment of each anchor rod are the same. At the same time, the influence of the transverse slope of the bridge deck is ignored when calculating the moment at the bottom of the support 5 of the first short T-beam 3 on the water-facing surface. ;

[0128] ——One span at both ends of the bridge deck The total moment of anchor rod 6 is: ;

[0129] ——The weight of water, ;

[0130] ——Design flood velocity, ;

[0131] ——The acceleration due to gravity is equal to 9.81, ;

[0132] ——Friction coefficient between the bottom of the short T-beam and the support 5;

[0133] ——respectively the weight and volume of the bridge deck system, ;

[0134] ——are the bending stiffness of the block 21 in the water-facing direction, the shear stiffness of the support 5, and the shear deformation modulus of the spring 63, respectively. ;

[0135] ——Elastic modulus of upper and lower anchor rods, ;

[0136] ——respectively the tensile stress and allowable tensile stress of the straight segment anchor rod 6, ;

[0137] ——respectively the shear stress and allowable shear stress of spring 63, ;

[0138] ——The maximum compression spring deformation under the maximum combined bridge deck load, ;

[0139] ——The maximum tensile deformation and allowable tensile deformation of spring 63, .

[0140] The construction method of the flood-resistant anchoring structure of the low T-beam flood bridge mainly includes the following steps:

[0141] Step 1: Research, testing and calculation

[0142] ① Investigate, drill and measure the geographical, geological and hydrological conditions of the project site to obtain data on engineering geology, flood design frequency and flow rate;

[0143] ② Determine the bridge span, number of spans, foundation and lower connection, and the connection structure of the low T-beam bridge deck system;

[0144] ③ Calculate the anchor rod size according to Formula 1 to Formula 3, optimize the spring parameters according to the characteristics of the rubber bearing, design the low T-beam flood bridge and propose the materials and construction process requirements;

[0145] Step 2: Foundation and substructure construction

[0146] ①Measure and stake out the bridge position and pile foundation;

[0147] ②Construct pile foundations and piers according to design requirements;

[0148] ③ Construction of cap beam 2: Install cast-in-place brackets and formwork for the cap beam, tie cap beam reinforcement including block reinforcement and support pad reinforcement, expose 1cm to 2cm of the upper end of the lower anchor rod from the top of the cap beam for spring welding, weld the lower anchor rod to other reinforcements firmly, pour cap beam concrete, cover with geotextile and perform concrete curing;

[0149] Step 3: Prefabrication of short T beams

[0150] ①Level the low T-beam prefabrication site and make the low T-beam prefabrication template;

[0151] ② Tie ordinary steel bars and prestressed steel bars of short T-beams;

[0152] ③ Casting of short T-beam 3, using automatic spraying for curing;

[0153] ④ After the short T-beam concrete reaches the specified strength, use the double-control program to tension the prestressed steel bars and promptly grout the prestressed steel bar holes;

[0154] Step 4: Bridge deck construction

[0155] ① Installation of low T beams: The prefabricated low T beams 3 are installed by means of lifting holes through the beam bottom or by means of a bridge erection machine. During the transportation, lifting and installation of the low T beams, attention should be paid to maintaining the lateral stability of the beam body. After erection, effective measures should be taken to strengthen temporary lateral support, and flange plates and beam wet joint steel bars should be welded in time to increase the stability and integrity of the beam body.

[0156] ②Support installation 5: Adjust the position of each low T-beam 5cm to 10cm above the support pad stone. After each low T-beam is in the correct position, place the support and accurately drop the beam;

[0157] ③ Installation of upper anchor rod 61: 1cm to 2cm of the lower end of the upper anchor rod is exposed at the bottom of the wet joint 41 for spring welding, and the upper anchor rod 61 and the steel bar of the wet joint 41 are welded firmly;

[0158] ④ Casting wet joints: installing wet joint formwork, casting wet joint concrete, and curing;

[0159] ⑤ Pour the hinged concrete of the flange plate of the low T beam and ensure that the concrete is cured;

[0160] ⑥ pouring bridge deck paving concrete, installing sidewalk 8 and railing 9;

[0161] ⑦ Welding spring: After the bridge deck structure is completed, the spring 63 is welded firmly to the lower end of the upper anchor rod 61 and the upper end of the lower anchor rod 62. If the reserved length of the lower end of the upper anchor rod and the upper end of the lower anchor rod is too long, it can be cut to a suitable length and then welded. If there is misalignment, the upper anchor rod and the lower anchor rod should be properly adjusted before cutting the reserved length of the lower end of the upper anchor rod and the lower anchor rod.

[0162] The above description is only a specific embodiment of the present invention. Those skilled in the art should understand that any structural design similar to this embodiment should be included in the protection scope of the present invention.

Claims

1. A flood-resistant anchoring structure for a low T-beam flood bridge, comprising a plurality of supports (5) installed on a cap beam (2) of a bridge pier (1) and a plurality of prefabricated low T-beams (3) arranged on the plurality of supports, each low T-beam being provided with a plurality of cross beams (4), the plurality of cross beams (4) of the plurality of low T-beams (3) being provided with mutually connected wet joints (41), a bridge deck pavement layer (7) being cast on the plurality of low T-beams (3), a sidewalk (8) and a handrail (9) being installed, Features An anchor rod (6) is provided between each wet joint (41) and the cap beam (2) for anchoring connection. The anchor rod is composed of an upper anchor rod (61) pre-buried in the wet joint (41), a lower anchor rod (62) pre-buried in the cap beam (2), and a spring (63) respectively connecting the upper and lower anchor rods, and the spring is located between the bottom of the wet joint (41) and the top of the cap beam (2).

2. The low T-beam flood bridge anti-flood anchoring structure according to claim 1, Features The short T-beam (3), wet joint (41), anchor rod (6), bridge deck pavement (7), sidewalk (8) and railing (9) are collectively referred to as the bridge deck system. When the flood just overflows the highest point of the sidewalk (8), the bridge deck system is subject to the maximum vertical buoyancy, which is simplified to a uniformly distributed load q sy At this time, the horizontal bridge is subjected to horizontal dynamic water pressure F sx It is also the largest; assuming that the bridge deck is under the action of its own weight, vertical buoyancy and horizontal hydrodynamic pressure, a span of short T-beam (3) rotates slightly clockwise with the center of the support (5) of the farthest short T-beam as the fulcrum Angle, according to the principle of force balance and elasticity theory, the following calculation formula is obtained: Formula 1: The force calculation formula of the bridge deck system and anchor rod (6) is as follows: Formula 2: The stress and diameter of the upper anchor rod (61) and the lower anchor rod (62) are calculated as follows: Formula 3: Under the action of the bridge deck system load, the compression amount of the compression spring (63) is not less than the maximum compression amount of the support. , and the spring (63) does not produce plastic deformation when subjected to tension under the horizontal hydrodynamic pressure of the flood, the relevant parameters of the spring (63) are calculated as follows: When the spring is compressed ， When the spring is stretched When the spring is compressed Substituting into the above formula needs to satisfy In formula 2 As in formula 3 When the values ​​are close, the diameter of the spring wire is the same as the diameter of the upper and lower anchor rods. , if the difference between the two is large, take the value according to the calculated result; The symbols in Formula 1, Formula 2 and Formula 3 are defined as: ——respectively the length of one span of the bridge and the full width of the bridge deck, ; ——respectively the spacing of anchor rods (6) embedded in the wet joint (41), the horizontal distance from the center of the first anchor rod on the water-facing side to the center of the support of the short T-beam side beam, the horizontal distance from the center of the support of the short T-beam side beam on the water-facing side to the water-facing side, and the width of the stopper (21) in the transverse direction of the bridge, ; ——are the diameter of the anchor rod (6), the mid-diameter of the spring, and the diameter of the spring wire material, respectively. ; ——are the pitch, clearance, elongation under maximum load and number of effective turns of the spring (63), respectively, , , , dimensionless; ——Water blocking height of bridge superstructure, ; ——respectively, the height of the stopper (21), the height of the support (5), the height of the water-facing surface of the bridge deck, the total length of the anchor rod (6), the length of the upper anchor rod (61) embedded in the wet joint (41), the height of the spring (63) from the bottom of the wet joint (41) to the top of the cap beam (2), and the length of the lower anchor rod (62) embedded in the cap beam (2), ; ——are the cross-sectional area of ​​the anchor rod (6) and the horizontal cross-sectional area of ​​the support (5), ; ——The number of anchor rods used to anchor the wet joint (41) on one side of a short T-beam (3) and a cap beam (2). There are n anchor rods at each end of a short T-beam (3) and they are numbered C. 1 , C 2 , C 3 , ..., C i , ..., C n ; ——The rotation angle of a span bridge deck system with the farthest short T-beam support as the fulcrum when subjected to horizontal hydrodynamic pressure, ; ——are the buoyancy and horizontal water dynamic pressure on the bridge deck system, ; ——are the horizontal hydrodynamic pressure, the horizontal reaction force of the end stopper (21) of the cap beam (2), and the horizontal friction resistance of the support (5), respectively. ; ——are respectively the elastic modulus of the support (5), the cross-sectional area of ​​the support (5), and the pressure on the support, ; ——Respectively Tension of the anchor rod (6), ; ——are the shear force and moment of the anchor rod (6). The anchor rod (6) is mainly subjected to tension, and the shear force and moment have little influence. In order to simplify the calculation, it is assumed that the shear force and moment of each anchor rod are the same. At the same time, the influence of the transverse slope of the bridge deck is ignored when calculating the moment at the bottom of the support (5) of the first short T-beam (3) on the water-facing surface. ; ——One span at both ends of the bridge deck The total moment on the anchor rod (6) is: ; ——The weight of water, ; ——Design flood velocity, ; ——The acceleration due to gravity is equal to 9.81, ; ——friction coefficient between the bottom of the short T-beam and the support (5); ——respectively the weight and volume of the bridge deck system, ; ——are respectively the bending stiffness of the stopper (21) in the water-facing direction, the shear stiffness of the support (5), and the shear deformation modulus of the spring (63), ; ——Elastic modulus of upper and lower anchor rods, ; ——respectively the tensile stress and allowable tensile stress of the straight segment anchor rod (6), ; ——respectively the shear stress and allowable shear stress of the spring (63), ; ——The maximum compression spring deformation under the maximum combined bridge deck load, ; ——maximum tensile deformation and allowable tensile deformation of the spring (63), .

3. The low T-beam flood bridge anti-flood anchoring structure according to claim 2, Features The bridge piers (1) and cap beams (2) are the lower structure of the flooded bridge and are reinforced concrete structures; the stoppers (21) are reinforced concrete structures and are arranged at both ends of the top of the cap beam (2).

4. The low T-beam flood bridge anti-flood anchoring structure according to claim 1, Features The short T-beam (3) is a prestressed concrete structure. The short T-beam is divided into two structural forms: a side beam and a middle beam. A single-span bridge deck is composed of two side beams and multiple middle beams.

5. The low T-beam flood bridge anti-flood anchoring structure according to claim 1, Features The cross beam (4) is a transverse connection structure of the short T beam (3). There is no cross beam on the outside of the side beam, and there are cross beams (4) on both sides of the middle beam. The cross beam (4) of each short T beam (3) has a certain width and is assembled and connected by the wet joint (41). Both ends of the short T beam (3) are provided with cross beams (4), and 3 to 4 cross beams are arranged along the span direction.

6. The low T-beam flood bridge anti-flood anchoring structure according to claim 1, Features The wet joint (41) is made of high-grade concrete, and is used to connect prefabricated short T-beam crossbeams in pairs to form a transverse connection of multiple short T-beams (3).

7. The low T-beam flood bridge anti-flood anchoring structure according to claim 1, Features The anchor rod (6) is made of ordinary steel, stainless steel or weathering steel. The anchor rod (6) is arranged in the wet joint of the crossbeam of the short T-beam (3) at the ends of both sides of a span. The upper anchor rod (61) is welded to the steel bars in the wet joint (41), and the lower anchor rod (62) is welded to the steel bars in the cap beam (2). The spring (63) is a compression spring. The two ends of the spring are firmly welded to the lower end of the upper anchor rod (61) and the upper end of the lower anchor rod (62). The maximum compression amount of the spring (63) including the clearance is not less than the maximum compression amount of the bearing of the bridge deck system under the combined load of the vehicle. The maximum stretching amount of the spring (63) must meet the maximum deformation requirement.

8. The low T-beam flood bridge anti-flood anchoring structure according to claim 1, Features The bearing (5) is a rubber bearing. Depending on the span, number of spans and the connection structure of the bridge deck system, a plate-type rubber bearing or a polytetrafluoroethylene plate sliding plate bearing is used.

9. The low T-beam flood bridge anti-flood anchoring structure according to claim 1, Features The bridge deck pavement layer (7) is a reinforced concrete structure. After the installation of multiple supports (5), multiple prefabricated low T-beams (3), wet joints (41), and anchor rods (6), the bridge deck pavement layer (7) is poured on the multiple prefabricated low T-beams (3), and then the sidewalk (8) and the handrail (9) are installed. Finally, the spring (63) is firmly welded to the upper anchor rod (61) and the lower anchor rod (62).

10. A construction method for the flood-resistant anchoring structure of a low T-beam flood bridge according to any one of claims 1 to 9, Features The construction method comprises the following steps: Step 1: Research, testing and calculation ① Investigate, drill and measure the geographical, geological and hydrological conditions of the project site to obtain data on engineering geology, flood design frequency and flow rate; ② Determine the bridge span, number of spans, foundation and lower connection, and the connection structure of the low T-beam bridge deck system; ③ Calculate the anchor rod size according to formula 1 to formula 3, optimize the spring parameters according to the characteristics of the rubber bearing, design the low T-beam flood bridge and propose the materials and construction process requirements; Step 2: Foundation and substructure construction ①Measure and stake out the bridge position and pile foundation; ②Construct pile foundations and piers according to design requirements; ③ Construction of the cap beam (2): installing cast-in-place support and formwork for the cap beam, tying the cap beam reinforcement including the block reinforcement and the support pad reinforcement, leaving the upper end of the lower anchor rod (62) exposed 1 cm to 2 cm from the top of the cap beam for spring welding, firmly welding the lower anchor rod (62) to other reinforcements, pouring the cap beam concrete, covering it with geotextile and curing the concrete; Step 3: Prefabrication of short T beams ① Level the low T beam (3) prefabrication site and make the low T beam prefabrication template; ② Tie ordinary steel bars and prestressed steel bars of short T-beams; ③ Casting the short T-beam (3) and using automatic spraying for curing; ④ After the short T-beam concrete reaches the specified strength, use the double-control program to tension the prestressed steel bars and promptly grout the prestressed steel bar holes; Step 4: Bridge deck construction ① Installation of low T beams: Prefabricated low T beams (3) are installed by using lifting holes through the beam bottom or by using a bridge erection machine. During the transportation, lifting and installation of low T beams, attention should be paid to maintaining the lateral stability of the beam. After installation, effective measures should be taken to strengthen temporary lateral support, and flange plates and beam wet joint steel bars should be welded in time to increase the stability and integrity of the beam. ②Support installation: adjust the position of each low T-beam 5cm to 10cm above the support pad stone. After each low T-beam is in the correct position, place the support and accurately drop the beam; ③ Installation of the upper anchor rod: 1 cm to 2 cm of the lower end of the upper anchor rod (61) is exposed at the bottom of the wet joint (41) for welding the spring (63), and the upper anchor rod (61) and the steel bar of the wet joint (41) are welded firmly; ④ Casting wet joints: Install the wet joint (41) formwork, cast wet joint concrete, and cure it properly; ⑤ Pour the hinged concrete of the flange plate of the low T beam and ensure that the concrete is cured; ⑥ Pouring bridge deck paving concrete, installing sidewalks (8) and railings (9); ⑦ Welding spring (63): After the bridge deck structure is completed, the spring is welded firmly to the lower end of the upper anchor rod (61) and the upper end of the lower anchor rod (62). If the reserved length of the lower end of the upper anchor rod and the upper end of the lower anchor rod is too long, it can be cut to a suitable length before welding. If there is misalignment, the upper anchor rod and the lower anchor rod are properly adjusted before cutting the reserved length of the lower end of the upper anchor rod and the lower anchor rod.

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