Seamless bridge assembled composite beam-steel pier and underground sliding cap foundation

Abstract

The invention discloses a seamless bridge assembled composite beam-steel pier and underground sliding abutment foundation, which relates to the technical field of seamless bridges and underground abutment foundations, including steel plate beams, concrete bridge decks, composite beams, steel piers, underground abutments, and combined abutments; the concrete bridge deck is connected to the steel plate beam by shear nails to form a composite beam; the steel pier is a steel structure portal pier, including a steel cap beam and a steel pier column; the steel plate beam intersects with the steel cap beam, and the concrete bridge deck on the upper part of the steel plate beam extends to the top of the steel cap beam; the lower part of the steel pier column is connected to the underground abutment, and the sliding abutment is divided into a sliding upper abutment and a sliding lower abutment; rectangular groove slideways are provided at intervals at the bottom of the sliding upper abutment, and rail-type raised sliding strips are provided at intervals at the upper surface of the sliding lower abutment, and the mutual cooperation of the rectangular groove slideway at the bottom of the sliding upper abutment and the rail-type raised sliding strip of the sliding lower abutment allows relative displacement inside the sliding abutment; the invention can be widely used in the construction of multi-span expansion joint-free bridges.

Description

Technical Field

[0001] The invention relates to the technical field of seamless bridges and underground cap foundations, and in particular to an assembled composite beam-steel pier for seamless bridges and an underground sliding cap foundation. Background Art

[0002] In order to avoid the longitudinal deformation of the main beam caused by material creep and temperature changes during bridge construction, expansion joints and expansion devices are often set in the bridge span and the connection between the bridge and the road surface to release the deformation and avoid adverse secondary internal forces in the structure. However, the expansion joints and expansion devices of the bridge will reduce the smoothness of the route and driving comfort during use, and they are easily damaged in the use environment, and it is very difficult to maintain and replace them after damage, and the overall cost is high. After a lot of experimental research and engineering practice, domestic and foreign researchers finally reached a consensus: for small and medium span bridges with smaller spans, directly canceling the expansion joints and expansion devices is an effective way to solve the problem, that is, using a bridge without expansion joints (referred to as a seamless bridge) to achieve seamless and integrated structure of the entire bridge span.

[0003] The advantages of seamless bridges mainly include: (1) During the construction of seamless bridges, there is no need to set expansion joints and expansion devices. In addition, since the side spans are allowed to be larger or the supports between the main beam and the abutment are eliminated, the number of pile foundations required is less than that of traditional bridges, which can save construction costs. (2) The expansion device at the abutment eliminates the defects, which improves driving comfort and speed, can meet the needs of high-speed driving, and reduces the cost of bridge management and maintenance. (3) The integrity, durability, and seismic performance of the bridge are significantly improved. Correspondingly, there are also obvious challenges when seamless bridges use traditional supports, piers, and abutment foundations: (1) The flexibility of the lower structure is affected. (1) The requirements are relatively high. When the span of the bridge is large, the additional internal forces generated by material creep and temperature changes will have a huge impact on the piers; (2) It is necessary to consider the interaction between the pile foundation and the soil on the side of the pile, as well as the reciprocating horizontal deformation of the pile foundation under the action of temperature, which leads to relative looseness of the pile foundation and the soil around the pile. The horizontal deformation of the pile top is the largest, and the stress in the pile increases to form a plastic hinge, thereby reducing its vertical bearing capacity. At the same time, the pile foundation that has undergone horizontal deformation can produce a large additional bending moment under the influence of vertical loads, resulting in a sharp increase in the horizontal displacement of the pile top of the pedestal; (3) The cast-in-place concrete construction method is difficult to meet the requirements for enhancing the integrity of the bridge.

[0004] For medium and large span bridges with large spans, there is currently no precedent for the construction of seamless bridge prefabricated composite beams-steel piers and underground sliding abutment foundation structures, and there are still a large number of problems to be solved in the existing technology. Summary of the invention

[0005] The purpose of the present invention is to provide a seamless bridge prefabricated composite beam-steel pier and underground sliding pedestal foundation structure construction technology. By allowing a certain relative displacement between the upper and lower pedestals of the underground sliding pedestal foundation, the seamless bridge structure can better release the additional internal force caused by material creep and temperature changes, and avoid the adverse interaction between the pedestal pile foundation and the soil on the pile side caused by the deformation of the flexible pile foundation under the action of temperature changes; and further use lubricating materials and related construction processes to reduce the friction burden of the underground sliding pedestal foundation, so that the material performance of the steel pier can be fully exerted and utilized, so that it can be widely used in the construction of multi-span seamless bridges.

[0006] The technical solution of the present invention is: a seamless bridge assembled composite beam-steel pier and underground sliding abutment foundation structure, including a steel plate beam, a concrete bridge deck, a composite beam, a steel pier, an underground abutment, and a composite abutment; shear nails are welded on the steel plate beam, the concrete bridge deck is located above the steel plate beam and is connected through shear nails to form a composite beam; the composite beam is located between two adjacent steel piers, and the steel pier is a steel structure portal pier, including a steel cap beam and a steel pier column; the steel plate beam intersects with the steel cap beam, and the concrete bridge deck on the upper part of the steel plate beam extends to the top of the steel cap beam; the lower part of the steel pier column is connected to the underground abutment, and the underground abutment is divided into an integral abutment and a There are two types of sliding abutments, with only one underground abutment closest to the center of the entire bridge span as an integral abutment, and all other steel piers are sliding abutments; the sliding abutments are divided into sliding upper abutments and sliding lower abutments; the bottom of the sliding upper abutment is provided with rectangular groove slideways at intervals, and the upper surface of the sliding lower abutment is provided with rail-type raised slideways at intervals, and the cooperation between the rectangular groove slideways at the bottom of the sliding upper abutment and the rail-type raised slideways of the sliding lower abutment allows relative displacement inside the sliding abutment; the combined abutment is composed of a buttress-type retaining wall and a steel pier; the concrete bridge deck is seamlessly connected with the abutment slab to achieve a bridge without expansion joints.

[0007] Preferably, the horizontal cross-sections of the sliding upper support platform and the sliding lower support platform are both rectangular in shape, the horizontal and vertical center axes of the two are aligned, and the length and width of the sliding lower support platform are more than 10 cm larger than those of the sliding upper support platform; a baffle is arranged at the edge of the sliding lower support platform to prevent excessive relative displacement between the sliding upper support platform and the sliding lower support platform.

[0008] Preferably, the steel cap beam is provided with a plurality of transverse partitions in the transverse direction of the bridge, the transverse partitions are provided with manual maintenance openings, and vertical stiffening plates and horizontal stiffening plate steel plates are welded to the edges of the manual maintenance openings; supporting stiffening ribs are arranged around the inside of the steel cap beam, and the supporting stiffening ribs are butt-jointed with the horizontal stiffening plate steel plates.

[0009] Preferably, the steel cap beam is provided with an opening corresponding to the steel pier column, the top of the steel pier column extends into the opening of the bottom plate of the steel cap beam, shear nails are arranged inside and outside the steel pier column extending into the steel cap beam, and the bottom of the steel cap beam is filled with concrete, and the concrete height is higher than the top of the steel pier column; a steel boot is welded at the junction of the steel pier column and the bottom of the steel cap beam, the steel boot is a trapezoidal steel plate, and the steel cap beam is fixed on the steel boot.

[0010] Preferably, the steel plate beam is divided into a mid-span section and a cantilever section, and the cantilever section is welded to the steel cap beam longitudinal bridge on both sides; the cantilever section includes an upper flange plate, a web plate and a lower flange plate, wherein the upper flange plate is located above the web plate and the lower flange plate is located below the web plate, and the top surface of the upper flange plate is flush with the top surface of the steel cap beam; the web plate corresponds to the internal cross diaphragm of the steel cap beam; the lower flange plate corresponds to the supporting stiffening rib; the upper flange plate is welded to the mid-span section of the steel plate beam, and the web plate and the lower flange plate are connected to the mid-span section of the steel plate beam using high-strength bolts.

[0011] Preferably, the buttress-type retaining wall has backfill soil above it, and the abutment slab is above the backfill soil; one side of the abutment slab is seamlessly cast-connected to the concrete bridge deck, and the other side is connected to the connecting road surface.

[0012] Preferably, the steel cap beam has a longitudinally penetrating opening, the steel pier can pass through the steel cap beam opening, and the steel cap beam can be lifted to a low position or a high position; a temporary device for lifting the steel cap beam is arranged on the top surface of the steel pier, formed by H-shaped steel, and can be removed after the lifting construction is completed; during construction, the rope is put around the steel ear of the steel cap beam, and the steel cap beam is pulled and lifted to the desired plane position.

[0013] Although the underground sliding cap and steel pier structure described in the present invention enable the seamless bridge to better cope with material creep and temperature change, it is difficult to achieve an ideal smooth sliding surface between the sliding upper cap and the sliding lower cap through design or construction means, so there must be friction resistance along the relative sliding direction, so it is necessary to pay attention to the friction effect of the sliding cap and its influence on the mechanical bearing characteristics of the steel pier column;

[0014] Considering the most unfavorable working condition of static friction, the present invention simplifies the stress condition of the steel pier column into a rigid compression rod model with one end fixed and the other end capable of lateral sliding. The actual load-bearing capacity of a single steel pier column is N’ , the following formula must be satisfied:

[0015]

[0016] in, N’ is the vertical bearing capacity that can be actually utilized when considering sliding friction of the steel pier column. A is the cross-sectional area of ​​a single steel pier, l is the length of the steel pier, Wis the bending section coefficient of the cross section of a single steel pier, f is the static friction coefficient between the sliding upper platform and the sliding lower platform, σ f is the design value of compressive strength of steel pier material;

[0017] Based on this, the actual vertical bearing capacity of the steel pier column can be obtained when considering sliding friction: N’ The calculation expression is:

[0018]

[0019] Due to the existence of friction of the sliding cap, the vertical bearing capacity of the steel pier column cannot be fully utilized to fully support the upper bridge load. Therefore, the reduction factor α is used to represent the effective utilization of the bearing capacity of the steel pier column. The calculation expression is as follows:

[0020]

[0021] Among them, α represents the effective utilization degree of the vertical bearing capacity of the steel pier, N’ is the vertical bearing capacity that can be actually utilized when considering sliding friction of the steel pier column. N The vertical bearing capacity of the steel pier column without considering the sliding friction;

[0022] From the above formula, it can be seen that the reduction factor α of the vertical bearing capacity of the steel pier column and the friction coefficient in the sliding cap are f , Steel Pier Length l , cross-sectional area of ​​a single steel pier A Negatively correlated with the bending section coefficient of a single steel pier W There is a positive correlation;

[0023] In order to avoid excessive impact on the effective utilization of the vertical bearing capacity of the steel pier, in addition to controlling and optimizing the length and cross-sectional geometry of the steel pier, reducing the friction coefficient inside the sliding cap is one of the effective directions. Therefore, during the construction of the underground sliding cap, the process of inlaying PTFE sheets and applying butter PTFE powder can effectively reduce the friction coefficient inside the sliding cap and avoid excessive impact on the utilization of the vertical bearing capacity of the steel pier.

[0024] Therefore, when using the underground sliding cap and steel pier structure described in the present invention, it is necessary to consider optimizing the friction coefficient inside the sliding cap. f , Steel Pier Length l 、Cross-sectional area of ​​steel pier A and bending section coefficient W The comprehensive influence of design parameters such as pressure relief and load-bearing capacity on the vertical bearing capacity of steel piers is considered, and lubricating materials and related processes are combined to reduce the friction in underground sliding caps.

[0025] A construction method for a seamless bridge assembled composite beam-steel pier and underground sliding cap foundation, characterized in that it comprises the following steps:

[0026] S100, Pile foundation construction: Pile position measurement and casing burial are carried out at the designed construction location of the bridge pile foundation. After the casing burial is completed, holes are drilled and pile foundation is poured;

[0027] S200, underground cap construction: underground caps are divided into two types: integral caps and sliding caps. For the whole bridge, only the underground cap closest to the center of the whole span is arranged as an integral cap, which is constructed directly on the pile foundation. First, the foundation pit is dug, the formwork is installed, the steel bars are tied, and the integral cap is cast in place and maintained.

[0028] The sliding cap is divided into the sliding upper cap and the sliding lower cap, which are constructed separately. Before the construction of the sliding lower cap, the cap foundation pit is excavated first, the sliding lower cap template is installed, the sliding lower cap steel bars are tied, the rail-type raised slide bar is fixed, the sliding lower cap concrete is poured, and the curing is carried out; then the sliding upper cap bottom template is installed, the rectangular groove slideway corresponding to the sliding lower cap rail-type raised slide bar is installed to make it fit with the rail-type raised slide bar, the sliding upper cap side template is installed, the sliding upper cap steel bars are tied, the sliding upper cap concrete is poured and cured; the length and width of the sliding lower cap on the horizontal plane are more than 10 cm larger than the sliding upper cap, and a baffle is set at the edge of the sliding lower cap to prevent excessive relative displacement between the sliding upper cap and the sliding lower cap;

[0029] As a preferred embodiment, step S200 also includes: the rectangular groove slideway at the bottom of the sliding upper platform is a steel slideway, and the contact surface with the rail-type raised slide bar of the sliding lower platform is fully polished and smoothed and inlaid with a polytetrafluoroethylene sheet and coated with butter polytetrafluoroethylene powder before installation and casting, so as to reduce the friction between the sliding upper platform and the sliding lower platform;

[0030] S300, Fabrication and installation of steel piers: The steel pier segments are processed and manufactured in the factory, and a part of the steel pier segments are embedded before the concrete of the underground pedestal is poured; after the steel pier segments are transported to the site, they are assembled with the embedded steel pier segments above the underground pedestal and partially filled with concrete.

[0031] S400, Fabrication and installation of steel cap beams: Fabricate steel cap beams in the factory, and reserve installation holes for steel piers; fabricate cantilever segments of steel plate beams and weld them to both sides of the longitudinal bridge of the steel cap beams; set multiple transverse diaphragms in the transverse bridge direction inside the steel cap beams, and the transverse diaphragms are provided with openings for manual maintenance, with vertical stiffening plates and horizontal stiffening plates welded to the edges of the openings; set supporting stiffening ribs inside the steel cap beams to connect with the horizontal stiffening plates at the edges of the transverse diaphragm openings, and set horizontal stiffening ribs around them; after the steel cap beams are prefabricated in the factory and transported to the site, they are hoisted to the predetermined position and connected to the steel piers;

[0032] S500, connection construction between steel pier column and steel cap beam: After the steel cap beam is hoisted and lifted to the predetermined position, the steel cap beam and the steel plate of the steel pier column are welded, and shear nails are arranged around the steel pier column and filled with concrete, and finally the reserved steel pier column channel is closed; after the connection between the steel cap beam and the steel pier column is completed, steel boots are arranged at uniform intervals along the steel pier column at the bottom plate of the steel cap beam; the steel boots are welded to the bottom plate of the steel cap beam and the steel plate of the steel pier column respectively;

[0033] S600, Combined abutment construction: Cast the combined abutment foundation, and after the foundation casting is completed, cast the concrete buttress retaining wall; after the retaining wall casting and maintenance is completed, fill the soil behind the abutment during the roadbed construction, and the soil behind the abutment is partly on the buttress retaining wall.

[0034] S700, Fabrication and installation of steel plate beams: The prefabricated steel plate beam mid-span segment and the upper flange plate of the steel plate beam cantilever segment are welded to each other, and the web plates and lower flange plates of the two are connected with high-strength bolts;

[0035] Preferably, step S700 further includes prefabricating and assembling a plurality of sections in the mid-span of the steel plate beam;

[0036] S800, Prefabrication and installation of concrete bridge deck: The concrete bridge deck is prefabricated in the factory and transported to the site for assembly using a truck crane; the prefabricated concrete bridge deck is erected on the steel plate beam, and the extended steel bars and shear nails welded on the concrete steel plate beam are tied together to form a steel mesh, which is connected into a whole through secondary pouring of concrete on site, completing a seamless, support-free integrated structure of the entire bridge.

[0037] S900, Construction of bridge abutment rear slab: A bridge abutment slab is set above the backfill behind the abutment; one side of the bridge abutment slab is seamlessly cast and connected to the concrete bridge deck, and the other side is connected to the road surface.

[0038] Compared with the prior art, the beneficial effects of the present invention are: first, the mutual cooperation between the rectangular groove slide at the bottom of the sliding upper pedestal and the rail-type raised slide bar of the sliding lower pedestal allows a certain relative displacement inside the sliding pedestal, so that the seamless bridge structure can better release the additional internal force caused by material creep and temperature changes, and avoid the adverse interaction between the underground pedestal pile foundation and the soil on the side of the pile caused by the deformation of the flexible pile foundation under the action of temperature changes; second, combining lubricating materials and related processes to reduce the friction inside the sliding pedestal structure can make full use of the material properties of the steel piers and the underground sliding pedestal. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the full-bridge structure of an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of a sliding platform according to an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the sliding surface of the sliding platform according to an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of a combined abutment according to an embodiment of the present invention;

[0043] Figure numerals: 10-steel cap beam, 17-cantilever segment, 20-steel pier, 21-sliding pedestal, 22-steel pier column, 23-sliding upper pedestal, 24-sliding lower pedestal, 25-integral pedestal, 26-pile foundation, 27-railway type raised slide, 28-rectangular groove slide, 29-baffle, 30-combined beam, 31-steel plate beam, 32-high-strength bolts, 41-buttress retaining wall, 42-abutment foundation, 43-soil, 44-planking, 45-connection pavement, 50-concrete bridge deck. DETAILED DESCRIPTION

[0044] The following is a more detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and the accompanying drawings so that a person skilled in the art can implement the embodiments after reading the description. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] Embodiment 1:

[0046] like Figure 1-4 As shown, a seamless bridge assembled composite beam-steel pier and underground sliding abutment foundation includes: a steel plate beam 31, a concrete bridge deck 50, a composite beam 30, a steel pier 20, an underground abutment, and a composite abutment; shear nails are welded on the steel plate beam 31, the concrete bridge deck 50 is located above the steel plate beam 31 and is connected by shear nails to form a composite beam 30; the composite beam 30 is located between two adjacent steel piers 20, and the steel pier 20 is a steel structure portal pier, including a steel cap beam 10 and a steel pier column 22; the steel plate beam 31 intersects with the steel cap beam 10, and the concrete bridge deck 50 on the upper part of the steel plate beam 31 extends to the top of the steel cap beam 10; the lower part of the steel pier column 22 is connected to the underground abutment, and the underground abutment is divided into an integral abutment 25 and a sliding abutment 2 1, only the underground cap closest to the center of the whole bridge span is set as an integral cap 25, and the rest of the steel piers 20 are all sliding caps 21; the sliding cap 21 is divided into a sliding upper cap 23 and a sliding lower cap 24; the bottom of the sliding upper cap 23 is provided with a rectangular groove slide 28, and the upper surface of the sliding lower cap 24 is provided with a rail-type protruding slide 27; the mutual cooperation of the rectangular groove slide 28 at the bottom of the sliding upper cap 23 and the rail-type protruding slide 27 of the sliding lower cap 24 allows relative displacement inside the sliding cap 21; the combined abutment is composed of a buttress retaining wall 41 and a steel pier 20; the concrete bridge deck 50 is seamlessly connected with the abutment slab 44, so that the whole bridge has no expansion joints.

[0047] In a specific implementation, the horizontal cross-sections of the sliding upper platform 23 and the sliding lower platform 24 are both rectangular in shape, the horizontal and vertical center axes of the two are aligned, and the length and width of the sliding lower platform 24 are 10 cm larger than those of the sliding upper platform 23; and a baffle 29 is set at the edge of the sliding lower platform 24 to prevent excessive relative displacement between the sliding upper platform 23 and the sliding lower platform 24.

[0048] In a specific implementation, the steel cap beam 10 is provided with a plurality of transverse partitions in the transverse direction of the bridge, and the transverse partitions are provided with manual maintenance openings, and vertical stiffening plates and horizontal stiffening plates are welded to the edges of the manual maintenance openings; supporting stiffening ribs are arranged around the inside of the steel cap beam 10, and the supporting stiffening ribs are connected to the horizontal stiffening plates.

[0049] In the specific implementation, the steel cap beam 10 is provided with an opening corresponding to the steel pier column 22. The top of the steel pier column 22 extends into the opening of the bottom plate of the steel cap beam 10. Shear nails are arranged inside and outside the steel pier column 22 extending into the steel cap beam 10. Concrete is filled at the bottom of the steel cap beam 10, and the concrete height is higher than the top of the steel pier column 22. Steel boots are welded at the junction of the steel pier column 22 and the bottom of the steel cap beam 10. The steel boots are made of trapezoidal steel plates, and the steel cap beam 10 is fixed on the steel boots.

[0050] In the specific implementation, the steel plate beam 31 is divided into a mid-span section and a cantilever section 17, and the cantilever section 17 is welded to the steel cap beam 10 on both sides of the longitudinal bridge; the cantilever section 17 includes an upper flange plate, a web plate and a lower flange plate, wherein the upper flange plate is located above the web plate and the lower flange plate is located below the web plate, and the top surface of the upper flange plate is flush with the top surface of the steel cap beam 10; the web plate corresponds to the internal diaphragm of the steel cap beam 10; the lower flange plate corresponds to the supporting stiffening rib; the upper flange plate is welded to the mid-span section of the steel plate beam 31, and the web plate and the lower flange plate are connected to the mid-span section of the steel plate beam 31 using high-strength bolts 32.

[0051] In a specific implementation, the backfill soil 43 is located above the buttress retaining wall 41 , and the abutment slab 44 is located above the backfill soil 43 ; one side of the abutment slab 44 is seamlessly cast and connected to the concrete bridge deck 50 , and the other side is connected to the connecting road surface 45 .

[0052] In a specific implementation, the steel cap beam 10 is hoisted and lifted to the desired position, and the steel pier 22 passes through the opening of the steel cap beam 10; during hoisting, the rope is put on the steel ear of the steel cap beam 10, and the steel cap beam 10 is pulled and lifted to the desired plane position.

[0053] Although the underground sliding cap 21 and the steel pier 20 structure enable the seamless bridge to better cope with material creep and temperature change, it is difficult to achieve an ideal smooth sliding surface between the sliding upper cap 23 and the sliding lower cap 24 through design or construction means, so there must be friction resistance along the relative sliding direction. Therefore, it is necessary to pay attention to the friction effect of the sliding cap 21 and its influence on the mechanical bearing characteristics of the steel pier 22;

[0054] In the specific implementation, the seamless bridge steel pier 22 is made of Q235 steel, and its compressive strength design value is 215MPa. The length of the steel pier 22 is 10m, and the steel pier 22 is a square cross-section with an outer length of 1.2m and a wall thickness of 0.05m. The friction coefficient of the sliding pedestal is tested under the condition that the contact surface is fully polished and smooth. f 0.05; when the contact surface is fully polished and inlaid with PTFE sheet and coated with butter PTFE powder, the friction coefficient is f is 0.04.

[0055] Considering the most unfavorable working condition of static friction, the force condition of the steel pier column 22 is simplified to a rigid compression rod model with one end fixed and the other end capable of lateral sliding. The actual load-bearing capacity of a single steel pier column 22 is N’ , the following formula must be satisfied:

[0056]

[0057] in, N’ is the vertical bearing capacity of the steel pier 22 that can be actually utilized when considering sliding friction, A is the cross-sectional area of ​​a single steel pier 22, l The length of the steel pier 22, W is the bending section coefficient of the cross section of a single steel pier 22, f is the static friction coefficient between the sliding upper platform 23 and the sliding lower platform 24, σ f is the design value of the compressive strength of the steel pier 22 material;

[0058] Based on this, it can be concluded that the actual vertical bearing capacity of the steel pier 22 when considering sliding friction is N’ Calculate the expression:

[0059]

[0060] Due to the friction of the sliding cap 21, the vertical bearing capacity of the steel pier 22 cannot be fully utilized to fully support the upper bridge load. Therefore, the reduction factor α is used to represent the effective utilization of the bearing capacity of the steel pier 22. The calculation expression is as follows:

[0061]

[0062] Among them, α represents the effective utilization degree of the vertical bearing capacity of the steel pier 22, N’ is the vertical bearing capacity of the steel pier 22 that can be actually utilized when considering sliding friction, N In order to ignore the vertical bearing capacity of the sliding friction steel pier 22; therefore:

[0063] The vertical bearing capacity of the steel pier 22 inside the sliding cap 21 is N’ The calculated value is:

[0064]

[0065] The calculated value of the reduction factor α of the utilization degree of the vertical bearing capacity of the steel pier 22 is:

[0066] ;

[0067] Through the above calculations, it can be seen that the internal friction of the sliding cap 21 has a significant adverse effect on the vertical bearing capacity of the steel pier 22.

[0068] In specific implementation, the seamless bridge construction method includes the following steps:

[0069] S100, construction of pile foundation 26: measuring the pile position and burying the casing at the designed construction position of the bridge pile foundation 26, and drilling and pouring the pile foundation 26 after the casing is buried;

[0070] S200, underground cap construction: The underground cap is divided into integral cap 25 and sliding cap 21, which are constructed separately; only the underground cap closest to the center of the whole bridge span is arranged as integral cap 25, which is constructed directly above the pile foundation 26, first digging the foundation pit, installing the formwork, tying the hole steel bar, integrally cast in place, and curing;

[0071] Construction of the sliding cap 21: Before the construction of the sliding lower cap 24, first excavate the underground cap foundation pit, install the sliding lower cap 24 template, tie the sliding lower cap 24 steel bars, fix the rail-type raised slide 27, pour the sliding lower cap 24 concrete, and perform concrete curing; install the sliding upper cap 23 bottom template to form a rectangular groove slide 28 corresponding to the sliding lower cap 24 rail-type raised slide 27; install the sliding upper cap 23 side template, tie the sliding upper cap 23 steel bars, pour the sliding upper cap 23 concrete and maintain it; set a baffle 29 at the edge of the sliding lower cap 24 to prevent the sliding upper cap 23 and the sliding lower cap 24 from excessive displacement.

[0072] In specific implementation: the rectangular groove slideway 28 at the bottom of the sliding upper platform 23 is a steel slideway, and the contact surface with the rail-type raised slide bar 27 of the sliding lower platform 24 is fully polished and smooth before installation and pouring construction, thereby reducing friction;

[0073] S300, fabrication and installation of steel pier column 22: The steel pier column 22 segments are processed and fabricated in the factory, and a part of the steel pier column 22 segments are embedded before the concrete of the underground pedestal is poured; after the steel pier column 22 segments are transported to the site, they are assembled with the pre-embedded steel pier column 22 segments above the underground pedestal and partially filled with concrete.

[0074] S400, fabrication and installation of steel cap beam 10: fabricate steel cap beam 10 in factory, and reserve installation channel for steel pier column 22; fabricate cantilever segment 17 of steel plate beam 31 and weld it to both sides of longitudinal bridge direction of steel cap beam 10; set multiple transverse diaphragms in transverse bridge direction inside steel cap beam 10, and the transverse diaphragms are provided with manual maintenance openings, and vertical stiffening plates and horizontal stiffening plates are welded on the opening edges; support stiffening ribs are provided inside steel cap beam 10 to connect with horizontal stiffening plates on the opening edges of transverse diaphragms, and horizontal stiffening ribs are provided around; after prefabrication in factory and delivery to site, steel cap beam 10 is hoisted to the predetermined position and connected with steel pier column 22;

[0075] S500, connection construction between steel pier column 22 and steel cap beam 10: After the steel cap beam 10 is hoisted and lifted to the predetermined position, the steel cap beam 10 is welded to the steel plate of the steel pier column 22, and shear nails are arranged around the steel pier column 22 and filled with concrete, and finally the reserved steel pier column channel is closed; after the connection between the steel cap beam 10 and the steel pier column 22 is completed, steel boots are arranged at uniform intervals along the steel pier column 22 at the bottom plate of the steel cap beam 10; the steel boots are welded to the bottom plate of the steel cap beam 10 and the steel plate of the steel pier column 22 respectively;

[0076] S600, construction of combined abutment: pouring the abutment foundation 42, pouring the concrete buttress retaining wall 41 after the pouring is completed, and after the pouring and maintenance is completed, the soil 43 behind the abutment is filled during the roadbed construction, and part of the soil 43 behind the abutment is on the buttress retaining wall 41.

[0077] S700, fabrication and installation of steel plate beam 31: the mid-span segment of the prefabricated steel plate beam 31 and the upper flange plate of the cantilever segment 17 are welded to each other, and the web plates and lower flange plates of the two are connected by high-strength bolts 32;

[0078] In the specific implementation, the mid-span section of the steel plate beam 31 is prefabricated and assembled in several sections;

[0079] S800, prefabrication and installation of concrete bridge deck 50: The concrete bridge deck 50 is prefabricated in the factory and transported to the site for assembly using a truck crane; the prefabricated concrete bridge deck 50 is erected on the steel plate beam 31, and the extended steel bars and the shear nails welded on the steel plate beam 31 are tied to form a steel mesh, which is connected into a whole through secondary on-site pouring of concrete, completing a seamless, support-free integrated structure of the entire bridge.

[0080] S900, construction of the bridge abutment slab 44 behind the abutment: a bridge abutment slab 44 is set above the backfill behind the abutment; one side of the bridge abutment slab 44 is seamlessly cast and connected with the concrete bridge deck 50, and the other side is connected with the road surface.

[0081] Example 2

[0082] As an embodiment of the present invention, in a specific implementation: the rectangular groove slideway 28 at the bottom of the sliding upper platform 23 is a steel slideway, and the contact surface with the rail-type raised slide bar 27 of the sliding lower platform 24 is fully polished and smooth and inlaid with a polytetrafluoroethylene sheet and coated with butter polytetrafluoroethylene powder before installation and casting construction, so as to further reduce the internal friction of the sliding platform 21;

[0083] That is, the other conditions and conditions of Example 2 are the same as those of Example 1, except that the vertical bearing capacity of the steel pier 22 inside the sliding base 21 is 10 ... N’ The calculated value is:

[0084]

[0085] The calculated value of the reduction factor α of the utilization degree of the vertical bearing capacity of the steel pier 22 is:

[0086] ;

[0087] Through the above calculations, it can be seen that the adverse effect of the internal friction of the sliding cap 21 on the vertical bearing capacity of the steel pier 22 is still quite significant, but it has been significantly improved compared with Example 1.

[0088] Therefore, by comparing the difference between Examples 1 and 2, it can be seen that when using the sliding cap 21 and steel pier 22 structure of the present invention, attention should be paid to the length of the steel pier. l , cross-sectional area A , bending section coefficient W The comprehensive influence of design parameters such as and so on on the vertical bearing capacity of steel piers, especially the friction coefficient between sliding caps should be paid attention to. f , and combined with lubricating materials and related construction techniques to reduce the friction inside the underground sliding pedestal, so that the material properties of the sliding pedestal 21 and the steel pier 22 structure of the present invention can be fully utilized.

[0089] The above are one or more embodiments of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A seamless bridge assembled composite beam-steel pier and underground sliding cap foundation, characterized by: The seamless bridge comprises a steel plate beam, a concrete bridge deck, a composite beam, a steel pier, an underground cap, and a composite abutment; Shear nails are welded on the steel plate beam, and the concrete bridge deck is located above the steel plate beam and connected by shear nails to form a composite beam; the composite beam is located between two adjacent steel piers, and the steel pier is a steel structure portal pier, including a steel cap beam and a steel pier column; the steel plate beam intersects with the steel cap beam, and the concrete bridge deck on the upper part of the steel plate beam extends to the top of the steel cap beam; the lower part of the steel pier column is connected to the underground pedestal, and the underground pedestal is divided into two types: integral pedestal and sliding pedestal. Only the underground pedestal closest to the center of the entire bridge span is an integral pedestal, and the remaining steel piers are all sliding pedestals; the sliding pedestal is divided into sliding The upper pedestal and the lower pedestal are provided with a sliding type; the bottom of the upper pedestal is provided with rectangular groove slideways at intervals, and the upper surface of the lower pedestal is provided with rail-type raised slideways at intervals. The cooperation between the rectangular groove slideways at the bottom of the upper pedestal and the rail-type raised slideways of the lower pedestal allows relative displacement inside the sliding pedestal; the combined abutment is composed of a buttress-type retaining wall and a steel pier; the concrete bridge deck is seamlessly connected with the abutment slab; the backfill soil is above the buttress-type retaining wall, and the abutment slab is above the backfill soil; one side of the slab is seamlessly cast and connected with the concrete bridge deck, and the other side is connected with the connecting road surface; Considering the most unfavorable working condition of static friction, the force condition of the steel pier column is simplified to a rigid compression rod model with one end fixed and the other end capable of sliding laterally. The actual load-bearing capacity of a single steel pier column is N’ , the following formula must be satisfied: in, N’ is the vertical bearing capacity that can be actually utilized when considering sliding friction of the steel pier column. A is the cross-sectional area of ​​a single steel pier, l is the length of the steel pier, W is the bending section coefficient of the cross section of a single steel pier, f is the static friction coefficient between the sliding upper platform and the sliding lower platform, σ f is the design value of compressive strength of steel pier material; Based on this, the actual vertical bearing capacity of the steel pier column can be obtained when considering sliding friction: N’ The calculation expression is: The reduction factor α is used to represent the effective utilization of the bearing capacity of the steel pier. The calculation expression is as follows: Among them, α represents the effective utilization degree of the vertical bearing capacity of the steel pier, N’ is the vertical bearing capacity that can be actually utilized when considering sliding friction of the steel pier column. N The vertical bearing capacity of the steel pier without considering sliding friction.

2. A seamless bridge assembled composite beam-steel pier and underground sliding cap foundation according to claim 1, characterized in that: The horizontal cross-sections of the sliding upper support and the sliding lower support are both rectangular, the horizontal and vertical center axes of the two are aligned, and the length and width of the sliding lower support are 10 cm larger than those of the sliding upper support; a baffle is set at the edge of the sliding lower support.

3. The seamless bridge assembly type composite beam-steel pier and underground sliding cap foundation according to claim 1, characterized in that: The steel cap beam is provided with a plurality of transverse partitions, each of which is provided with a manual maintenance opening, and vertical stiffening plates and horizontal stiffening plates are welded to the edges of the manual maintenance openings; supporting stiffening ribs are arranged around the interior of the steel cap beam, and the supporting stiffening ribs are butt-jointed with the horizontal stiffening plates.

4. The seamless bridge assembly type composite beam-steel pier and underground sliding cap foundation according to claim 1, characterized in that: The steel cap beam is provided with an opening corresponding to the steel pier column, the top of the steel pier column extends into the opening of the bottom plate of the steel cap beam, shear nails are arranged inside and outside the steel pier column extending into the steel cap beam, and the bottom of the steel cap beam is filled with concrete, and the concrete height is higher than the top of the steel pier column; a steel boot is welded at the junction of the steel pier column and the bottom of the steel cap beam, the steel boot is a trapezoidal steel plate, and the steel cap beam is fixed on the steel boot.

5. The seamless bridge assembly type composite beam-steel pier and underground sliding cap foundation according to claim 1, characterized in that: The steel plate beam is divided into a mid-span section and a cantilever section, and the cantilever section is welded to the steel cap beam longitudinal bridge on both sides; the cantilever section includes an upper flange plate, a web plate and a lower flange plate, wherein the upper flange plate is located above the web plate and the lower flange plate is located below the web plate, and the top surface of the upper flange plate is flush with the top surface of the steel cap beam; the web plate corresponds to the internal cross diaphragm of the steel cap beam; the lower flange plate corresponds to the supporting stiffening rib; the upper flange plate is welded to the mid-span section of the steel plate beam, and the web plate and the lower flange plate are connected to the mid-span section of the steel plate beam using high-strength bolts.

6. The seamless bridge assembly type composite beam-steel pier and underground sliding cap foundation according to claim 1, characterized in that: The steel cap beam has a longitudinal opening, and the steel pier can pass through the opening of the steel cap beam, and the steel cap beam can be lifted to a low position or a high position; a temporary device for lifting the steel cap beam is arranged on the top surface of the steel pier, and is formed by H-shaped steel, and can be removed after the lifting construction is completed; during construction, the rope is put on the steel ear of the steel cap beam, and the steel cap beam is pulled and lifted to the desired plane position.

7. A construction method of a seamless bridge assembled composite beam-steel pier and underground sliding cap, characterized in that: The following steps are involved: S100, Pile foundation construction: Pile position measurement and casing burial are carried out at the designed construction location of the bridge pile foundation. After the casing burial is completed, holes are drilled and pile foundation is poured; S200, underground cap construction: underground caps are divided into two types: integral caps and sliding caps. For the whole bridge, only the underground cap closest to the center of the whole span is arranged as an integral cap, which is constructed directly on the pile foundation. First, the foundation pit is dug, the formwork is installed, the steel bars are tied, and the integral cap is cast in place and maintained. The sliding cap is divided into the sliding upper cap and the sliding lower cap, which are constructed separately. Before the construction of the sliding lower cap, the cap foundation pit is excavated first, the sliding lower cap template is installed, the sliding lower cap steel bars are tied, the rail-type raised slide bar is fixed, the sliding lower cap concrete is poured, and the curing is carried out; then the sliding upper cap bottom template is installed, the rectangular groove slideway corresponding to the sliding lower cap rail-type raised slide bar is installed to make it fit with the rail-type raised slide bar, the sliding upper cap side template is installed, the sliding upper cap steel bars are tied, the sliding upper cap concrete is poured and cured; the length and width of the sliding lower cap on the horizontal plane are more than 10 cm larger than the sliding upper cap, and a baffle is set at the edge of the sliding lower cap to prevent excessive relative displacement between the sliding upper cap and the sliding lower cap; S300, Steel Pier Column Manufacturing and Installation: The factory processes and manufactures steel pier column segments, and a part of the steel pier column segments are embedded before the underground cap concrete is poured; after the steel pier column segments are transported to the site, they are assembled with the pre-embedded steel pier column segments above the underground cap and partially filled with concrete; S400, Fabrication and installation of steel cap beams: Fabricate steel cap beams in the factory, and reserve installation holes for steel piers; fabricate cantilever segments of steel plate beams and weld them to both sides of the longitudinal bridge of the steel cap beams; set multiple transverse diaphragms in the transverse bridge direction inside the steel cap beams, and the transverse diaphragms are provided with openings for manual maintenance, with vertical stiffening plates and horizontal stiffening plates welded to the edges of the openings; set supporting stiffening ribs inside the steel cap beams to connect with the horizontal stiffening plates at the edges of the transverse diaphragm openings, and set horizontal stiffening ribs around them; after the steel cap beams are prefabricated in the factory and transported to the site, they are hoisted to the predetermined position and connected to the steel piers; S500, connection construction between steel pier column and steel cap beam: After the steel cap beam is hoisted and lifted to the predetermined position, the steel cap beam and the steel plate of the steel pier column are welded, and shear nails are arranged around the steel pier column and filled with concrete, and finally the reserved steel pier column channel is closed; after the connection between the steel cap beam and the steel pier column is completed, steel boots are arranged at uniform intervals along the steel pier column at the bottom plate of the steel cap beam; the steel boots are welded to the bottom plate of the steel cap beam and the steel plate of the steel pier column respectively; S600, Combined abutment construction: Cast the combined abutment foundation, and after the foundation is cast, cast the concrete buttress retaining wall; after the retaining wall is cast and maintained, fill the soil behind the abutment during the roadbed construction, and the soil behind the abutment is on the buttress retaining wall; S700, Fabrication and installation of steel plate beams: The prefabricated steel plate beam mid-span segment and the upper flange plate of the steel plate beam cantilever segment are welded to each other, and the web plates and lower flange plates of the two are connected with high-strength bolts; S800, Prefabrication and installation of concrete bridge deck: The concrete bridge deck is prefabricated in the factory and transported to the site for assembly using a truck crane; the prefabricated concrete bridge deck is erected on the steel plate beam, and the protruding steel bars of the prefabricated concrete bridge deck are tied with the shear nails welded on the concrete steel plate beam to form a steel mesh, which is connected into a whole through secondary pouring of concrete on site, completing a seamless and support-free integrated structure of the entire bridge; S900, Construction of bridge abutment rear slab: A bridge abutment slab is set above the backfill behind the abutment; one side of the bridge abutment slab is seamlessly cast and connected to the concrete bridge deck, and the other side is connected to the road surface.

8. The construction method of a seamless bridge assembled composite beam-steel pier and underground sliding cap according to claim 7 is characterized by: Step S200 also includes: the rectangular groove slideway at the bottom of the sliding upper support is a steel slideway, and the contact surface with the rail-type raised slide bar of the sliding lower support is fully polished and smooth before installation and pouring, and Teflon sheets are embedded and coated with butter Teflon powder.

9. The construction method of a seamless bridge assembled composite beam-steel pier and underground sliding cap according to claim 7 is characterized by: Step S700 also includes prefabricating and assembling a plurality of segments in the mid-span of the steel plate beam.

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