Bearing platform structure suitable for large-span bridge under soft soil foundation condition

Abstract

The utility model relates to a bearing platform structure suitable for a long-span bridge under the soft soil foundation condition, which comprises a plurality of pile foundations arranged in a plurality of rows and a plurality of columns at intervals; the reinforced concrete bottom plate and the pile foundation are poured into a whole through reserved steel bars at the top of the pile foundation, and the reinforced concrete bottom plate is provided with a plurality of transverse prestressed steel bars and longitudinal prestressed steel bars which are vertically arranged; the bearing platform is located in the center of the reinforced concrete bottom plate. The height of the supporting beams is equal to that of the bearing platform, the height of the supporting beams is equal to that of the bearing platform, the supporting beams comprise the first supporting beams and the second supporting beams, and the first supporting beams and the second supporting beams form a grid structure; the reinforced concrete top plate is located above the bearing platform and the supporting beam and connected into a whole through reserved steel bars at the top of the bearing platform and the top of the supporting beam. The size and performance of the pile foundation are optimized by improving the stress state of the pile foundation, the diameter of the pile foundation of a large-span bridge under the same load condition is effectively reduced, and therefore input and construction time of special drilling equipment are reduced.

Description

Technical Field

[0001] This application relates to the field of bridge construction, and in particular to a pier structure suitable for long-span bridges under soft soil foundation conditions. Background Technology

[0002] With the rapid development of transportation networks and urban infrastructure, bridge structures and spans are constantly expanding. The widespread application of long-span suspension bridges, cable-stayed bridges, and arch bridges has led to increasingly larger bridge spans, placing higher demands on the bearing capacity of the foundation. Bridge construction faces even greater challenges, especially in areas with soft soil foundations or deep rock formations.

[0003] According to the "Code for Design of Highway Bridge and Culvert Foundations" (JTG 3363-2019), the settlement of pile foundations in soft soil foundations needs to be controlled within L / 1500 (L is the bridge span). Although traditional large-diameter pile foundations (d≥2.5m) have high bearing capacity, they have a long construction period (the construction period for a single φ4m pile is ≥15 days) and cause serious vibration and noise pollution.

[0004] In soft soil foundations, traditional pile foundation construction methods often require large-diameter, long piles to meet the bridge's bearing capacity requirements. However, this method not only necessitates specialized drilling equipment but can also significantly increase pile foundation costs and extend the construction period. Furthermore, uneven settlement and insufficient bearing capacity in soft soil foundations pose potential risks to the long-term stability and safety of the bridge. Summary of the Invention

[0005] This application provides a pier cap structure suitable for long-span bridges under soft soil foundation conditions, in order to solve the problem in related technologies that the use of large-diameter, long-pile-length piles leads to a significant increase in pile foundation costs and a significant extension of construction period.

[0006] Firstly, a pier cap structure suitable for long-span bridges under soft soil foundation conditions is provided, including:

[0007] Pile foundations, wherein multiple pile foundations are arranged at intervals in multiple rows and columns;

[0008] The reinforced concrete base slab is cast integrally with the pile foundation by pre-reserved steel bars at the top of the pile foundation. The reinforced concrete base slab is provided with multiple transverse prestressed steel bars and longitudinal prestressed steel bars arranged perpendicularly to each other.

[0009] The foundation is located at the center of the reinforced concrete base slab.

[0010] The support beam has the same height as the pier and the same height as the pier. It includes a first support beam and a second support beam. Multiple first support beams and second support beams form a grid structure.

[0011] A reinforced concrete top slab is located above the foundation and the supporting beam, and is connected as a whole by reserved steel bars at the top of the foundation and the supporting beam.

[0012] In some embodiments, the spacing between adjacent piles is not less than four times the pile diameter.

[0013] In some embodiments, the diameter of the pile foundation is 0.8 to 2.0 m.

[0014] In some embodiments, the intersection of the first support beam and the second support beam is collinear with the axis of the pile foundation.

[0015] In some embodiments, the wall thickness of the support beam is not less than the diameter of the pile foundation.

[0016] In some embodiments, the support beam is a lattice beam.

[0017] Secondly, a construction method for the pier cap structure of a long-span bridge under soft soil foundation conditions is provided, including the following steps:

[0018] Based on the bridge structural design, calculate and determine the number and diameter of piles that meet the bearing capacity of the pile foundation, the size of the pile cap and the design of the supporting beam frame, and the design of the prestressed steel reinforcement of the reinforced concrete base slab.

[0019] Construction of pile foundations, with steel reinforcement reserved at the top of the pile foundations;

[0020] A reinforced concrete base slab is constructed at the top of the pile foundation, and transverse and longitudinal prestressed steel bars are installed and tensioned.

[0021] A solid intermediate foundation was cast in place in the middle of the reinforced concrete base slab.

[0022] Construct supporting beams around the central solid foundation;

[0023] A reinforced concrete slab is cast in place on top of the foundation and supporting beams;

[0024] Construct bridge piers or towers on top of reinforced concrete slabs.

[0025] In some embodiments, the prestressed steel bars of the reinforced concrete base slab are constructed using the post-tensioning method, and grouting is performed after tensioning is completed.

[0026] In some embodiments, the support beam is constructed using prefabricated reinforced concrete in a factory and assembled on-site.

[0027] Thirdly, a bridge is provided, including the aforementioned abutment structure suitable for long-span bridges under soft soil foundation conditions.

[0028] This application provides a pier cap structure suitable for long-span bridges on soft soil foundations. Compared to conventional pier caps, the grid-structured support beams around the pier cap increase the contact area between the pier cap and the pile foundation by approximately 3-4 times. With the same pile diameter and spacing, the number of piles can be increased by 3-4 times. Therefore, the bearing capacity requirement of a single pile is reduced by 1 / 4 to 1 / 3 compared to conventional designs. With a fixed pile length, the bearing capacity of a single pile is directly proportional to the pile diameter, effectively reducing the pile diameter. Using smaller diameter piles instead of larger diameter piles allows for mature pile construction technology, higher construction quality precision, and exponentially reduced construction time (a 1.5m diameter pile of the same length can be completed in one day, but a 4m diameter pile requires more than half a month). It also reduces the investment in large drilling rigs and other equipment (the daily rental cost of a large drilling rig is several times or even tens of times that of a regular drilling rig), while avoiding problems such as vibration and mud pollution that may occur during large-diameter pile construction.

[0029] By tensioning transverse and longitudinal prestressed steel bars in a reinforced concrete base slab to bear the loads transferred from the superstructure to the pile cap and pile foundation, the stress state of the pile foundation will change as follows under prestressing:

[0030] (1) Improve the stress distribution of pile foundation

[0031] The prestressed tendons at the bottom of the pile cap generate compressive stress in the pile foundation, which offsets part of the tensile stress caused by external loads; and this compressive stress can be evenly distributed in the pile body and surrounding soil, reducing local stress concentration in the pile foundation.

[0032] (2) Resisting the punching shear force of the pile foundation

[0033] Prestressed tendons can guide the load to be transferred more evenly to the pile foundation, optimize the load transfer path, and reduce local stress concentration. At the same time, the prestressed stress field formed in the foundation slab of the prestressed tendons can effectively offset the shear stress caused by the punching shear load of the pile foundation and improve the shear strength of the concrete of the foundation slab.

[0034] (3) Enhance the friction between piles and soil

[0035] Prestressing makes the contact between the pile and the surrounding soil tighter, increasing the effective stress between the pile and the soil. This increased effective stress also raises the friction coefficient at the pile-soil interface, thus enhancing friction. Therefore, the bearing capacity per unit pile surface area is increased. Under the same load conditions, the required pile-soil contact area can be reduced, allowing for the use of smaller diameter piles, significantly reducing construction costs and time.

[0036] (4) Reduce the settlement of pile foundations

[0037] Prestressing can reduce the settlement of pile foundations under load and increase the stiffness of the pile foundations; and the reduction in settlement means that the deformation of the pile foundations is smaller and the stress distribution of the soil is more uniform.

[0038] Therefore, this application expands the contact area between the pile cap and the pile foundation by setting up a grid-structured support beam around the pile cap, allowing multiple small-diameter pile foundations to share the load. At the same time, a reinforced concrete base slab is set at the bottom of the pile cap and the support beam. The reinforced concrete base slab, through transverse and longitudinal prestressed steel bars, evenly distributes the upper load to the pile foundation, reducing local stress concentration. Through the synergistic effect of the grid-structured support beam, the prestressed steel bars set in the reinforced concrete base slab, and the small-diameter pile foundations, a complete stress optimization system is formed to improve the stress state of the pile foundation, thereby optimizing the size and performance of the pile foundation. This effectively reduces the pile foundation diameter of long-span bridges under the same load conditions, thereby reducing the investment in special drilling equipment and construction time. It has a great promoting effect on cost reduction and efficiency improvement in the construction of long-span bridges, especially in areas with soft soil foundations or deep rock strata. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A schematic diagram of the elevation structure of a pier cap for a long-span bridge under soft soil foundation conditions, provided as an embodiment of this application;

[0041] Figure 2 This is a schematic diagram of the plan structure of a pier cap for a long-span bridge under soft soil foundation conditions, provided as an embodiment of this application.

[0042] In the diagram: 1. Pile foundation; 2. Reinforced concrete base slab; 21. Transverse prestressed steel bars; 22. Longitudinal prestressed steel bars; 3. Pier; 4. Support beam; 41. First support beam; 42. Second support beam; 5. Reinforced concrete top slab; 6. Pier. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] This application provides a pier cap structure suitable for long-span bridges under soft soil foundation conditions, which can solve the problem of large-diameter, long-pile-length pile foundations used in related technologies, which leads to a significant increase in pile foundation costs and a significant extension of construction period.

[0045] like Figure 1 , Figure 2 As shown, a pier cap structure suitable for long-span bridges under soft soil foundation conditions includes:

[0046] Pile foundation 1, multiple pile foundations 1 are arranged in multiple rows and columns at intervals;

[0047] The reinforced concrete base slab 2 is cast together with the pile foundation 1 by pre-reserved steel bars at the top of the pile foundation 1. The reinforced concrete base slab 2 is provided with multiple transverse prestressed steel bars 21 and longitudinal prestressed steel bars 22 arranged perpendicularly to each other. The prestress control parameter is 0.75fptk.

[0048] Foundation 3 is located at the center of reinforced concrete base slab 2.

[0049] Support beam 4, whose bottom is integrated with the upper surface of reinforced concrete base slab 2, and whose sidewalls are attached to the perimeter of pier 3. The beam height is the same as that of pier 3, including first support beam 41 and second support beam 42. Multiple first support beams 41 and second support beams 42 form a grid structure.

[0050] The reinforced concrete top slab 5 is located above the foundation 3 and the support beam 4, and is connected as a whole by the reserved steel bars at the top of the foundation 3 and the support beam 4.

[0051] Furthermore, the diameter of pile foundation 1 is 0.8 to 2.0 m.

[0052] Furthermore, pile foundation 1 is a friction pile foundation.

[0053] Specifically, the small-diameter friction pile foundation acts directly on the ground. In this embodiment, the diameter is 1.2m. In some optional embodiments, the diameter is consistent with the pile diameter of other small-span bridges on the same route, so as to reuse the drilling equipment and reduce the cost of special equipment.

[0054] A pier cap structure suitable for long-span bridges on soft soil foundations utilizes transverse and longitudinal prestressed steel bars 21 and 22 in a reinforced concrete base slab 2 to bear the loads transmitted from the superstructure, improving the stress distribution of the pile foundation 1. Compressive stress is generated in the prestressed tendons of the pile foundation 1 at the bottom of the pier cap 3, offsetting some of the tensile stress and reducing local stress concentration. The grid support beam 4 increases the contact area between the pier cap 3 and the pile foundation 1, allowing for an increase in the number of pile foundations 1 with the same pile diameter and spacing, thus reducing the bearing capacity requirement of a single pile. For small-diameter piles with reduced perimeter and cross-sectional area, the transverse and longitudinal prestressed steel bars of the reinforced concrete base slab 2 and the grid support beam 4 ensure close contact with the soil, enhancing pile-soil friction. These three elements work together to form a complete stress optimization system, resulting in a more uniform and rational stress distribution throughout the structure. Compared with conventional pile caps, the contact area between pile cap 3 and pile 1 can be increased by about 3-4 times. Under the same pile diameter and pile spacing, the number of piles 1 can be increased by 3-4 times. Therefore, the bearing capacity requirement of a single pile 1 is reduced by 1 / 4 to 1 / 3 compared with conventional design. The formula for calculating the bearing capacity of a single pile 1 of friction type pile foundation is as follows:

[0055]

[0056] K: Safety factor (usually taken as 2);

[0057] u: Pile circumference (u = πd, d is the pile diameter);

[0058] q sik Characteristic value of side friction resistance of the i-th soil layer (provided by the geological report);

[0059] l i : The length of the pile in the i-th soil layer;

[0060] q pk Characteristic value of pile end resistance;

[0061] A p : Pile tip cross-sectional area (A p =πd 2 / 4).

[0062] For friction-type pile foundations, given a fixed pile length, the bearing capacity of a single pile is directly proportional to the pile diameter, which can effectively reduce the pile diameter. This invention, through the synergistic effect of the transverse and longitudinal prestressed steel bars of the reinforced concrete base slab 2 and the grid support beam 4, increases the bearing capacity of a single pile by 30%–40%, allowing the pile diameter to be reduced to φ1.2m and the construction cycle shortened to 3 days per pile. Using smaller diameter pile foundations instead of larger ones offers mature pile foundation construction technology, higher construction quality precision, and exponentially reduced construction time (a 1.2m diameter pile foundation of the same length can be completed in three days, but a 4m diameter pile foundation requires more than half a month). It also reduces the investment in large drilling rigs and other equipment (the daily rental cost of a large drilling rig is several times or even tens of times that of an ordinary drilling rig), while avoiding problems such as vibration and mud pollution that may occur during the construction of large-diameter piles.

[0063] Furthermore, the spacing between adjacent pile foundations 1 shall not be less than 4 times the diameter of pile foundation 1.

[0064] As the area of ​​pile foundation 1 increases, the pile diameter decreases, and the pile spacing increases, the number of pile foundation 1 can be adjusted, and the pile diameter and pile spacing can be optimized so that the pile spacing is ≥4d, thereby reducing the group pile effect and improving the utilization efficiency of the single pile bearing capacity of friction pile foundation 1.

[0065] Furthermore, the cross-sectional area of ​​the reinforced concrete base slab 2 is 1 to 1.5 times that of the cross-sectional area of ​​the foundation 3.

[0066] Specifically, the volume of the support beams 4 around the foundation 3, which is the enlarged part of the foundation, is only 1-1.5 times larger than that of a conventional foundation. Furthermore, the concrete construction of the support beams 4 can be done using precast components. Compared with conventional foundations, the increased material and construction time input of the lattice foundation 3 is much less than that of pile foundations, thus significantly reducing the overall cost and construction time.

[0067] A pier cap structure suitable for long-span bridges under soft soil foundation conditions. This pier cap structure bears the load transferred from the superstructure to the pier cap and pile foundation by tensioning transverse prestressed steel bars 21 and longitudinal prestressed steel bars 22 in a reinforced concrete base slab 2. Under prestressing, the stress state of the pile foundation 1 will change as follows:

[0068] (1) Improve the stress distribution of pile foundation 1

[0069] The prestressed tendons at the bottom of the pile cap 3 generate compressive stress in the pile foundation 1, which offsets part of the tensile stress caused by the external load; and this compressive stress can be evenly distributed to the pile body and the surrounding soil, reducing local stress concentration in the pile foundation 1.

[0070] (2) Resisting the punching shear force of pile foundation 1

[0071] The transverse prestressed steel bars 21 and the longitudinal prestressed steel bars 22 can guide the load to be transferred more evenly to the pile foundation 1, optimize the load transfer path, and reduce local stress concentration. At the same time, the prestress field formed by the prestress in the reinforced concrete base plate 2 at the bottom of the pile cap 21 can effectively offset the shear stress caused by the punching shear load of the pile foundation 1 and improve the shear strength of the reinforced concrete base plate 2 of the pile cap.

[0072] (3) Enhance the friction between piles and soil

[0073] Prestressing makes the contact between the pile and the surrounding soil tighter, increasing the effective stress between the pile and the soil. This increased effective stress also raises the friction coefficient at the pile-soil interface, thus enhancing friction. Therefore, the bearing capacity per unit pile surface area is increased. Under the same load conditions, the required pile-soil contact area can be reduced, allowing for the use of small-diameter piles, significantly reducing construction costs and time.

[0074] (4) Reduce the settlement of pile foundation 1

[0075] Prestressing can reduce the settlement of pile foundation 1 under load and increase the stiffness of pile foundation 1; and the reduction in settlement means that the deformation of pile foundation 1 is smaller and the stress distribution of the soil is more uniform.

[0076] The prestress values ​​of the transverse and longitudinal prestressed steel bars in the reinforced concrete base slab 2 were optimized to match the stiffness of the grid support beam 4, thus enhancing the collaborative work between the reinforced concrete base slab 2, support beam 4, and pile foundation 1. The grid support beam has suitable stiffness (moment of inertia ≥ 0.8m). 4 When combined with prestressed steel bars, the prestressed steel bars can work together better, guiding the load to be evenly transferred to pile foundation 1, thus optimizing the load transfer path. The synergy of the three optimizes the mechanical properties of the entire structural system, and the overall bearing capacity is increased by more than the sum of the effects of each part acting alone, exhibiting nonlinear improvement characteristics.

[0077] Meanwhile, in this embodiment, the prestressed reinforced concrete base slab 2 bears most of the tensile stress, and the concrete around the foundation 3 does not need to be solid. Therefore, the design of the crisscrossing lattice support beams 4 can greatly reduce the amount of concrete used in the foundation 3, and also reduce the difficulty and workload of temperature control for large-volume concrete.

[0078] In this embodiment, the foundation 3 is square. In some alternative embodiments, the foundation can be rectangular, circular, or racetrack-shaped. For ease of construction calculation, a square foundation is preferred.

[0079] Furthermore, piers 6 or bridge towers are installed on the pier cap 3.

[0080] In this embodiment, the support beam 4 is a lattice beam. The lattice structure of the support beam 4 not only enhances the overall stiffness and load-bearing capacity of the support beam, but also optimizes the efficiency of material use and reduces the structural self-weight.

[0081] In some embodiments, the support beam 4 can be prefabricated in a factory. This prefabrication method can significantly improve construction quality and efficiency, reduce on-site construction time and labor costs, and ensure the accuracy and consistency of component dimensions, thereby improving the safety and reliability of the overall project.

[0082] In this embodiment, the intersection of the first support beam 41 and the second support beam 42 is collinear with the axis of the pile foundation 1, ensuring a more direct and efficient force transmission path and improving the stability and durability of the overall structure.

[0083] In this embodiment, the wall thickness of the support beam 4 is not less than the diameter of the pile foundation 1, which enhances the supporting force of the support beam 4 and ensures that it can maintain the integrity and safety of the structure when bearing a large load, thereby extending the service life of the structure.

[0084] A construction method for the pier cap structure of a long-span bridge under soft soil foundation conditions includes the following steps:

[0085] Based on the bridge structural design, calculate and determine the number and diameter of piles that meet the bearing capacity of pile foundation 1, the dimensions of pile cap 3 and the frame design of support beam 4, and the prestressed steel reinforcement design of reinforced concrete base slab 2.

[0086] Construction pile 1, with reinforcement bars reserved at the top of pile 1;

[0087] A reinforced concrete base slab 2 is constructed on top of pile foundation 1, and transverse prestressed steel bars 21 and longitudinal prestressed steel bars 22 are installed and tensioned.

[0088] A solid intermediate foundation 3 is cast in place in the middle of the reinforced concrete base slab 2;

[0089] Construct support beams 4 around the solid central foundation 3;

[0090] A reinforced concrete top slab 5 is cast in place on top of the foundation 3 and the supporting beam 4;

[0091] Construct bridge piers 6 or bridge towers on top of the reinforced concrete top slab 5.

[0092] It should be noted that the reinforced concrete base slab 2 is cast together with the pile foundation 1 by pre-reserved steel bars at the top of the pile foundation 1. It is equipped with longitudinal prestressed steel bars 22 and transverse prestressed steel bars 21, and is constructed using the post-tensioning method. Grouting is performed after tensioning is completed.

[0093] In some alternative embodiments, the support beam 4 is constructed from precast reinforced concrete in a factory and assembled on-site.

[0094] In summary, the pier cap structure provided by this invention optimizes the size and performance of the pile foundation 1 by improving its stress state, effectively reducing the diameter of the pile foundation 1 for long-span bridges under the same load conditions, thereby reducing the investment in special drilling equipment and construction time. Simultaneously, it reduces the amount of concrete used in the pier cap 3 structure and lowers the difficulty of temperature control for large-volume concrete, improving the construction quality of the pier cap 3. The prefabricated assembly construction of the support beam 4 also shortens the construction period and improves construction quality. Therefore, this invention greatly promotes cost reduction and efficiency improvement in the construction of long-span bridges, especially those in areas with soft soil foundations or deep rock strata.

[0095] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0096] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0097] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A pier cap structure suitable for long-span bridges under soft soil foundation conditions, characterized in that, include: Pile foundations (1), multiple pile foundations (1) are arranged in multiple rows and columns at intervals; The reinforced concrete base slab (2) is cast together with the pile foundation (1) by the reserved steel bars at the top of the pile foundation (1). The reinforced concrete base slab (2) is provided with multiple transverse prestressed steel bars (21) and longitudinal prestressed steel bars (22) arranged perpendicularly to each other. The foundation (3) is located at the center of the reinforced concrete base slab (2); The support beam (4) has the same height as the pier (3) and includes a first support beam (41) and a second support beam (42). Multiple first support beams (41) and second support beams (42) form a grid structure. The reinforced concrete top slab (5) is located above the foundation (3) and the support beam (4) and is connected as a whole by the reserved steel bars at the top of the foundation (3) and the support beam (4).

2. The pier cap structure for long-span bridges under soft soil foundation conditions as described in claim 1, characterized in that: The spacing between adjacent piles (1) shall not be less than 4 times the pile diameter.

3. The pier cap structure for long-span bridges under soft soil foundation conditions as described in claim 1, characterized in that: The cross-sectional area of ​​the reinforced concrete base plate (2) is 1 to 1.5 times that of the cross-sectional area of ​​the foundation (3).

4. The pier cap structure for long-span bridges under soft soil foundation conditions as described in claim 1, characterized in that: The pile foundation (1) is a friction pile foundation.

5. The pier cap structure for long-span bridges under soft soil foundation conditions as described in claim 1, characterized in that: The diameter of the pile foundation (1) is 0.8 to 2.0 m.

6. The pier cap structure for long-span bridges under soft soil foundation conditions as described in claim 1, characterized in that: The intersection of the first support beam (41) and the second support beam (42) is collinear with the axis of the pile foundation (1).

7. The pier cap structure for long-span bridges under soft soil foundation conditions as described in claim 1, characterized in that: The wall thickness of the supporting beam (4) is not less than the diameter of the pile foundation (1).

8. The pier cap structure for long-span bridges under soft soil foundation conditions as described in claim 1, characterized in that: The supporting beam (4) is a lattice beam.

9. The pier cap structure for long-span bridges under soft soil foundation conditions as described in claim 1, characterized in that: The platform (3) is square or rectangular.

10. The pier cap structure for long-span bridges under soft soil foundation conditions as described in claim 1, characterized in that: Bridge piers (6) or bridge towers are installed on the pier (3).

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