Concrete construction method for steel-concrete combined bent cap

Abstract

The invention provides a concrete construction method of a steel-concrete combined cover beam, aiming at a steel box cover beam under the conditions of light weight and complex internal structure, firstly, the performance of concrete is specifically limited, and secondly, in the pouring mode, a plurality of pouring holes are formed in the top surface of a steel box at intervals in the length direction of the steel box, so that the steel-concrete combined cover beam is formed in the top surface of the steel box. A non-pressure hopper is adopted to feed self-compacting concrete into the pouring hole to fill the inner space of the steel box. On the premise that the mechanical property and the volume stability of the concrete are guaranteed, the passing performance of the concrete in a narrow space is improved by adjusting the mixing ratio, and the self-compacting performance of the concrete is improved, so that the concrete can be smoothly and completely filled during construction; and the risk of deformation and damage of the steel box caused by overlarge local pressure due to complex structure of stiffening ribs and steel strands in the steel box and poor trafficability of concrete when a pumping construction mode is used is eliminated, and an unexpected construction effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of construction of capping beams, and particularly to a concrete construction method for a steel-concrete composite capping beam. Background Art

[0002] A capping beam, also known as a coping beam, is an indispensable part of a bridge structure. Its main function is to provide support for the superstructure, disperse and transfer loads to the substructure. At the top of a column-type pier, the capping beam plays a key role in connecting the upper and lower parts of the bridge. Especially in simply supported bridges, the capping beam, as an important component connecting the upper and lower structures, is responsible for effectively transferring the loads of the superstructure to the foundation.

[0003] With the continuous growth of traffic demands in China, the trend in the construction of highway and urban bridges is to increase the number of lanes and widen the bridge deck, which leads to an increase in the number of beam slices in the transverse direction of the bridge. In the face of various terrain restrictions such as overpasses, rivers, and valleys, as well as flood discharge and environmental protection requirements, the transverse spacing and pier height of piers are also increasing continuously. Therefore, in the construction of large bridges, capping beams are increasingly applied in large-span scenarios, and the requirements for their structural design and mechanical properties are also increasing day by day.

[0004] The steel-concrete composite capping beam structure is composed of a steel strip-shaped closed box body, with stiffening rib plates provided inside and outside. Concrete is poured into the box body. Compared with traditional reinforced concrete capping beams, this composite capping beam does not require internal steel bar binding, so it has a lighter self-weight. The closed box body itself serves as a grouting formwork, eliminating the cumbersome steps of steel bar binding and making the manufacturing process more simple and efficient. The concrete is poured into the inner cavity of the closed box body. After its strength is formed, it forms an integral stress-bearing structure with the steel box body. This structure makes full use of the high compressive strength of concrete and the advantages of steel, achieving an optimized combination of materials. The steel box body and the internal concrete work together to bear the load, improving the flexural and tensile ultimate bearing capacity and toughness of the structure, and significantly enhancing the bearing performance of the capping beam. Due to its excellent performance, the steel-concrete composite capping beam can well meet the requirements of high loads, large spans, and high seismic intensities, showing excellent development potential and application prospects.

[0005] When constructing a steel-concrete composite cap beam, concrete is usually poured by pressurized pumping. In this process, a pouring hole is provided at the bottom of one end of the cap beam steel box for connecting the pump pipe, and a slurry pipe is provided at the top surface of the other end. Concrete enters from the pouring hole, and when the concrete emerges from the slurry pipe, the pouring is stopped. However, there are certain challenges in the actual construction of the steel-concrete composite cap beam. Due to the complex internal structure of the steel box, which contains many steel strands and stiffening ribs, when these internal components are too dense, the pressurized pumping pouring process may cause the concrete flow in the box to be blocked. Under the action of high pump pressure, the local pressure of the box may rise sharply. Once the pressure exceeds the design allowable value, it may cause the box to deform, bulge, or even crack the local stiffening ribs, resulting in economic losses.

[0006] Therefore, it is of great significance to develop a concrete construction method suitable for steel-concrete composite cap beams with overly dense internal structures. Summary of the invention

[0007] The purpose of the present invention is to provide a concrete construction method for a steel-concrete composite cap beam, in view of the fact that in the construction process of the prior art steel-concrete composite cap beam, when the internal structure of the cap beam steel box is too densely arranged, the conventional method of pouring concrete by pressurized pumping will cause deformation and bulging of the box chamber, and local stiffening ribs will be cracked. For the steel box under special conditions with complex internal structure, by adjusting the concrete performance and coordinating the pouring method, the concrete can be smoothly filled while ensuring the mechanical properties and volume stability of the concrete during construction, and the risk of deformation and damage of the steel box caused by the use of a pumping construction method for concrete due to the complex structure of the stiffening ribs and steel strands inside the steel box is eliminated, thereby achieving unexpected construction effects.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is: A concrete construction method for a steel-concrete composite cap beam, wherein a plurality of pouring holes are arranged at intervals along the length direction of the steel box top surface; When the height difference between the two ends of the steel box is less than 10cm, the construction includes: Mixing self-compacting concrete; The pouring is carried out in two times, each time using a pressureless hopper, starting from the pouring hole at one end of the steel box to the pouring hole at the other end; When the height difference between the two ends of the steel box is ≥10cm, the construction includes: Mixing self-compacting concrete; Stage 1 pouring: pouring is carried out in two times, each time using a pressureless hopper, starting from the pouring hole at one end of the steel box to the pouring hole at the other end, until the concrete liquid level reaches the lower end level; Stage II pouring: Divide the area between the pouring holes into independent pouring units and pour them one by one in the order from the lower end to the higher end; Among them, the mass ratio of the paste in the self-compacting concrete is ≥50%, the maximum aggregate size is ≤20 mm, the aggregate with a particle size of 10 - 20 mm does not exceed 30% of the total volume, the slump is 250 - 280 mm, and the spread is 600 - 650 mm.

[0009] This application provides a concrete construction method for a steel-concrete composite capping beam, mainly aiming at a steel box with multiple prestressed steel tendons, criss-crossing stiffeners and beam guiding plates arranged inside. The gap spacing inside the steel box is 5 - 20 cm, and the height-thickness ratio of the steel box web is ≥90. For such a special steel box, first, this application makes targeted limitations on the performance of the concrete. The mass ratio of the paste in the self-compacting concrete is ≥50%, the maximum aggregate size is ≤20 mm, the aggregate with a particle size of 10 - 20 mm does not exceed 30% of the total volume, the slump is 250 - 280 mm, and the spread is 600 - 650 mm; secondly, in terms of the pouring method, several pouring holes are arranged at intervals along the length direction of the top surface of the steel box, and a non-pressure hopper is used to pour the self-compacting concrete into the pouring holes to fill the internal space of the steel box. When the two ends of the steel box in the length direction are at different heights, the second-stage unitized sequential pouring is carried out. Through the adjustment of the concrete performance and the cooperation of the pouring method, when the concrete is constructed, on the premise of ensuring the mechanical properties and volume stability of the concrete, it can be successfully filled, eliminating the risk of steel box deformation and damage caused by the complex structure of the stiffeners and steel strands inside the steel box to the pumping construction method of the concrete, and achieving an unexpected construction effect.

[0010] Furthermore, the self-compacting concrete is prepared from the following raw materials by weight: 340 - 400 parts of cement, 750 - 800 parts of sand, 500 - 550 parts of small stones with a particle size of 5 - 10 mm, 400 - 450 parts of stones with a particle size of 10 - 20 mm, 30 - 60 parts of fly ash, 160 - 165 parts of water, 6 - 8 parts of water reducer, 40 - 45 parts of expansion agent.

[0011] Furthermore, the self-compacting concrete also includes 1 - 2 parts of water retention agent, 1 - 2 parts of air-entraining agent, and 2 - 3 parts of defoaming agent.

[0012] Furthermore, the spacing between adjacent pouring holes is ≤4 m. Preferably, the spacing between adjacent pouring holes is 3 - 4 m.

[0013] Further, exhaust holes are provided between adjacent perfusion holes. The provision of exhaust holes can better discharge gas and improve the compactness of the top. Preferably, a number of exhaust holes are spaced between adjacent perfusion holes. Preferably, the aperture of the exhaust holes is 1-2 cm. The distance between two adjacent exhaust holes is 0.8-1.2 m.

[0014] Further, the diameter of the perfusion holes is 10-20 cm.

[0015] Further, the non-pressure hopper is a V-shaped hopper; the passing time of the self-compacting concrete in the non-pressure hopper is 10-20 s. The passing time through the V-shaped hopper is a method for testing the properties of concrete, and 10-20 seconds is the performance index. The passing time can indirectly reflect the workability and passing performance of the concrete. The passing time of the self-compacting concrete in the non-pressure hopper is an important index for controlling the properties of the concrete.

[0016] Further, during perfusion, the self-compacting concrete is placed into the hopper, and the hopper is lifted by a crane to the perfusion hole for discharging.

[0017] Further, when perfusion is carried out in two times, For the first perfusion, each perfusion hole is perfused to the middle position. When the perfusion of the last perfusion hole is completed, the height of the concrete in the box chamber is 20-30 cm away from the height of the perfusion hole; For the second perfusion, the hopper returns to the initial perfusion hole for pouring. When it is full, the perfusion hole is immediately blocked, and then it is moved to the next perfusion hole until all the perfusion holes are blocked.

[0018] Using the perfusion method provided by the present application, the concrete can be smoothly and densely poured into the steel box. The construction is convenient, the time cost can be effectively saved, and the compactness of the formed concrete is high, the effect is good, and there will be no bulging or other deformation conditions.

[0019] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are: The present application provides a concrete construction method for a steel-concrete composite capping beam, mainly aiming at a steel box with multiple prestressed steel bundles, criss-crossing stiffeners and cable guiding plates arranged inside. The gap spacing inside the steel box is 5-20 cm, and the height-thickness ratio of the steel box web is ≥90. For such a steel box under special conditions, firstly, the present application makes targeted limitations on the performance of the concrete. The mass ratio of the paste in the self-compacting concrete is ≥50%, the maximum aggregate particle size is ≤20 mm, the aggregate with a particle size of 10-20 mm does not exceed 30% of the total volume, the slump is 250-280 mm, and the spread is 600-650 mm. Secondly, in terms of the pouring method, a number of pouring holes are arranged at intervals along the length direction of the top surface of the steel box. The self-compacting concrete is introduced into the pouring holes through a non-pressure hopper to fill the internal space of the steel box. When the two ends of the steel box in the length direction are at different heights, the second-stage sequential pouring in sub-units is carried out. Through the adjustment of the concrete performance and the cooperation of the pouring method, when the concrete is constructed, on the premise of ensuring the mechanical properties and volume stability of the concrete, it can be successfully filled, eliminating the risk of steel box deformation and damage caused by the complex structure of the stiffeners and steel strands inside the steel box to the pumping construction method of the concrete, and achieving an unexpected construction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the steel box structure for pouring concrete using the pressure pumping method.

[0021] Figure 2 Diagram of the bulging situation of the steel box during the pressure pumping of concrete.

[0022] Figure 3 Diagram of the internal situation of the steel box.

[0023] Figure 4 Schematic diagram of the steel box structure provided by the present application.

[0024] Figure 5 Field construction drawing of pouring concrete in the embodiment.

[0025] Figure 6 Construction drawing of pouring concrete using a hopper in the embodiment.

[0026] Figure 7 Schematic diagram of the method situation of using the present invention for concrete construction in another embodiment.

[0027] ICON: 1 - Pouring hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The present invention will be described in detail below with reference to the accompanying drawings.

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. 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.

[0030] Unless otherwise specified, in the description of the specific embodiments of the present invention, the expression terms indicating the orientation or positional relationship, such as "upper", "lower", "left", "right", "center", "inner", "outer", etc., are all based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the invention product / device / equipment is usually placed. These terms of orientation or positional relationship are only for the convenience of describing the solution of the present invention or simplifying the description in the specific embodiments, so as to facilitate technicians to quickly understand the solution, rather than indicating or implying that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, it should not be construed as a limitation of the present invention.

[0031] In addition, if terms such as "horizontal", "vertical", "hanging", "parallel" appear, it does not mean that the corresponding device / component / element is required to be absolutely horizontal or vertical or hanging or parallel, but can be slightly inclined or have a deviation. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. Or, it can be simply understood that the corresponding device / component / element is arranged in the directions of "horizontal", "vertical", "hanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the solution of the present invention.

[0032] In addition, the expressions such as "first", "second", "third", etc. in the terms are only used to distinguish the description of the same or similar components, and should not be understood as emphasizing or implying the relative importance of specific components.

[0033] In addition, in the description of the embodiments of the present invention, "several", "multiple", "a number of" represent at least 2. It can be any situation such as 2, 3, 4, 5, 6, 7, 8, 9, etc., or even more than 9.

[0034] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0035] In the prior art, when constructing a steel-concrete composite cap beam, concrete is usually poured by pressurized pumping. In this process, a pouring hole is provided at the bottom of one end of the cap beam steel box for connecting a pump pipe, and a slurry pipe is provided at the top surface of the other end. Concrete enters from the pouring hole, and when the concrete emerges from the slurry pipe, the pouring is stopped. However, in the actual construction of the steel-concrete composite cap beam, there are certain challenges. Due to the complex internal structure of the steel box, which contains many steel strands and stiffening ribs, when these internal components are too dense, the pressurized pumping pouring process may cause the concrete to flow obstructed in the box. Under the action of higher pump pressure, the local pressure of the box may rise sharply. Once the pressure exceeds the design allowable value, it may cause the box to deform, bulge, or even crack the local stiffening ribs, resulting in economic losses.

[0036] Specifically, the complex internal structure of the steel box is defined as: multiple prestressed steel strands, criss-crossing stiffening ribs and guide plates are arranged inside the steel box; the gap spacing inside the steel box is 5 to 20 cm; the height-to-thickness ratio of the steel box web is ≥90.

[0037] The present invention provides a concrete construction method for a steel-concrete composite cap beam, wherein a plurality of pouring holes are arranged at intervals along the length direction of the steel box top surface; When the height difference between the two ends of the steel box is less than 10cm, the construction includes: Mixing self-compacting concrete; The pouring is carried out in two times, each time using a pressureless hopper, starting from the pouring hole at one end of the steel box to the pouring hole at the other end; When the height difference between the two ends of the steel box is ≥10cm, the construction includes: Mixing self-compacting concrete; Stage 1 pouring: pouring is carried out in two times, each time using a pressureless hopper, starting from the pouring hole at one end of the steel box to the pouring hole at the other end, until the concrete liquid level reaches the lower end level; Phase 2 pouring: Divide the area between the pouring holes into independent pouring units and pour them one by one in the order from the short end to the high end; Among them, the mass ratio of the paste in the self-compacting concrete is ≥50%, the maximum aggregate size is ≤20 mm, the aggregate with a particle size of 10 - 20 mm does not exceed 30% of the total volume, the slump is 250 - 280 mm, and the spread is 600 - 650 mm.

[0038] This application provides a concrete construction method for a steel-concrete composite capping beam. It is mainly aimed at a steel box with multiple prestressed steel bundles, criss-crossing stiffeners and beam guiding plates arranged inside. The gap spacing inside the steel box is 5 - 20 cm, and the height-thickness ratio of the steel box web is ≥90. For such a special steel box, first, this application specifically limits the performance of the concrete. The mass ratio of the paste in the self-compacting concrete is ≥50%, the maximum aggregate size is ≤20 mm, the aggregate with a particle size of 10 - 20 mm does not exceed 30% of the total volume, the slump is 250 - 280 mm, and the spread is 600 - 650 mm. Secondly, in terms of the pouring method, a number of pouring holes are arranged at intervals along the length direction of the top surface of the steel box. The self-compacting concrete is fed into the pouring holes through a non-pressure hopper to fill the internal space of the steel box. If the two ends of the steel box in the length direction are at different heights, then the second-stage unit-by-unit sequential pouring is carried out. Through the adjustment of the concrete performance and the cooperation of the pouring method, when the concrete is constructed, on the premise of ensuring the mechanical properties and volume stability of the concrete, it can be successfully filled, eliminating the risk of steel box deformation and damage caused by the complex structure of the stiffeners and steel strands inside the steel box to the concrete pumping construction method, and achieving an unexpected construction effect.

[0039] In some embodiments, the self-compacting concrete is prepared from the following raw materials by weight: 340 - 400 parts of cement, 750 - 800 parts of sand, 500 - 550 parts of small stones with a particle size of 5 - 10 mm, 400 - 450 parts of stones with a particle size of 10 - 20 mm, 30 - 60 parts of fly ash, 160 - 165 parts of water, 6 - 8 parts of water reducer, and 40 - 45 parts of expansion agent. Prepared according to the provided concrete formula, it is easier to prepare self-compacting concrete, achieving good pouring performance and completing the pouring under non-pressure state with excellent effects.

[0040] In some embodiments, the self-compacting concrete further includes 1 - 2 parts of water retention agent, 1 - 2 parts of air-entraining agent, and 2 - 3 parts of defoaming agent.

[0041] In some embodiments, the spacing between adjacent pouring holes is ≤4 m. Preferably, the spacing between adjacent pouring holes is 3 - 4 m.

[0042] In some embodiments, exhaust holes are provided between adjacent perfusion holes. The provision of exhaust holes can better discharge gas and improve the top compactness. Preferably, a number of exhaust holes are spaced between adjacent perfusion holes. Preferably, the aperture of the exhaust holes is 1-2 cm. The spacing between two adjacent exhaust holes is 0.8-1.2 m.

[0043] In some embodiments, the diameter of the perfusion holes is 10-20 cm.

[0044] In some embodiments, the non-pressure hopper is a V-shaped funnel; the passing time of the self-compacting concrete in the non-pressure hopper is 10-20 s. The passing time of the V-shaped funnel is a method for detecting the performance of concrete, and 10-20 seconds is the performance index. The passing time can indirectly reflect the workability and the passing performance of the concrete. The passing time of the self-compacting concrete in the non-pressure hopper is an important index for controlling the performance of the concrete.

[0045] In some embodiments, during perfusion, the self-compacting concrete is placed into the hopper, and the hopper is lifted by a crane to the perfusion hole for discharging.

[0046] In some embodiments, when perfusion is carried out in two times, For the first perfusion, each perfusion hole is perfused to the middle position. When the perfusion of the last perfusion hole is completed, the height of the concrete in the box chamber is 20-30 cm away from the height of the perfusion hole; For the second perfusion, the hopper returns to the initial perfusion hole for pouring. When it is full, the perfusion hole is immediately blocked, and then it is moved to the next perfusion hole until all the perfusion holes are blocked.

[0047] By using the perfusion method provided by the present application, the concrete can be smoothly and densely poured into the steel box. The construction is convenient, the time cost can be effectively saved, and the density of the formed concrete is high, the effect is good, and there will be no bulging or other deformation conditions.

[0048] Therefore, the following detailed description is made according to the specific situation of a certain construction site: As Figures 1-3 shown, in a certain construction site, the maximum height of the capping beam is 3.7 m, the thickness of the capping beam is only 44 cm. There are 36 prestressed steel bundles arranged in the space with a thickness of only 44 cm, and there are criss-crossing stiffening ribs and beam guiding plates. The gap spacing in the steel box is 5-20 cm, and the height-to-thickness ratio of the steel box web is ≥90.

[0049] Tests have shown that for the concrete in the steel-concrete composite capping beam prepared with a C40 capping beam and pier column concrete formula that meets industry standards, when it is poured using the pressurized pumping method, a pouring hole 1 is provided at the bottom of one end of the capping beam steel box to connect the pump pipe, and a slurry overflow pipe is provided at the top surface position of the other end of the capping beam steel box. The concrete enters from the position of the pouring hole 1, and the pouring stops when the concrete emerges from the position of the slurry overflow pipe. However, during the construction of the steel-concrete composite capping beam, it is found that due to the relatively complex internal structure of the steel box, there are a large number of steel strands and stiffeners, and the internal structure of the steel box is too dense. The steel plate used for this type of capping beam is only 1.8 - 2.0 cm, and the out-of-plane stiffness of this structural form is weak. Using the pressurized pumping pouring process is extremely likely to cause bulging deformation of the capping beam web and cracking of local stiffeners, resulting in economic losses.

[0050] As Figures 4-5 shown, for the steel box under such special conditions, firstly, the performance of the concrete is specifically limited in this application. Secondly, in terms of the pouring method, a number of pouring holes 1 are arranged at intervals along the length direction of the top surface of the steel box, and a non-pressure hopper is used to introduce self-compacting concrete into the pouring holes 1 to fill the internal space of the steel box. Through the adjustment of the concrete performance and the cooperation of the pouring method, when the concrete is constructed, on the premise of ensuring the mechanical properties and volume stability of the concrete, it can be smoothly filled, eliminating the risk of steel box deformation and damage caused by the complex structure of the internal stiffeners and steel strands of the steel box when using the pumping construction method for the concrete.

[0051] The specific operation is as follows: Adjust self-compacting concrete with special performance requirements. The specific concrete formula is shown in Table 1.

[0052] In the self-compacting concrete, the mass ratio of the paste is ≥50%, the maximum aggregate particle size is ≤20 mm, the aggregate with a particle size of 10 - 20 mm does not exceed 30% of the total volume, the slump is 250 - 280 mm, and the spread is 600 - 650 mm.

[0053] Table 1 Raw material formula of self-compacting concrete Unit (parts)

[0054] Mix sand, gravel, cement, fly ash, and expansion agent evenly by mass, take half of the amount of water, add it and mix to obtain a mixture. Mix the water-reducing agent, water-retaining agent, air-entraining agent, defoaming agent and the remaining amount of water evenly by mass, add it to the mixture, and stir evenly to obtain the concrete mixture. The workability slump of the mixture is controlled at 250 - 280 mm, the spread is 600 - 650 mm, and the passing time through the V-funnel is controlled within 10 - 20 s.

[0055] A number of perfusion holes 1 are arranged at intervals along the length direction of the top surface of the steel box. The distance between adjacent perfusion holes 1 is 3 - 4 m, and the diameter of the perfusion hole 1 is 10 - 20 cm. Preferably, exhaust holes are arranged between adjacent perfusion holes. Arranging exhaust holes can better discharge gas and improve the top compactness. Preferably, a number of exhaust holes are arranged at intervals between adjacent perfusion holes. Preferably, the aperture of the exhaust hole is 1 - 2 cm. The distance between two adjacent exhaust holes is 0.8 - 1.2 m.

[0056] Transport the concrete mixture from the tanker to the pouring site, place the concrete into the hopper, and use a crane to lift the hopper to the pouring hole for discharging. The discharging is carried out from one end of the box body to the other end. The discharging is carried out in sequence from the perfusion hole 1 at one end of the box body to the perfusion hole 1 at the other end, and two rounds of perfusion are carried out.

[0057] In the first round, each perfusion hole 1 is perfused to the middle position. When the perfusion of the last perfusion hole 1 is completed, the height of the concrete in the box chamber is 20 - 30 cm away from the height of the perfusion hole 1. In the second round, the hopper returns to the initial perfusion hole 1 for pouring. When it is filled, immediately block the perfusion hole 1, and then move to the next perfusion hole 1 until all perfusion holes 1 are blocked.

[0058] Practice has proved that by using the concrete construction method provided by the present invention, on the premise of ensuring the mechanical properties and volume stability of the concrete, it can be successfully filled, and the risk of deformation and damage of the steel box caused by the complex structure of the stiffeners and steel strands inside the steel box to the concrete pumping construction method can be eliminated.

[0059] At the same time, through a large number of experimental explorations by the inventor, when the concrete performance does not meet the following conditions, the perfusion work of the concrete in the steel box cannot be successfully completed, and there will be problems such as unqualified concrete work performance, or accumulation and blockage during the perfusion process.

[0060] Concrete conditions: The mass ratio of the paste in the self - compacting concrete ≥ 50%, the maximum aggregate size ≤ 20 mm, the aggregate with a particle size of 10 - 20 mm does not exceed 30% of the total volume, the slump is 250 - 280 mm, and the spread is 600 - 650 mm.

[0061] In some embodiments, such as Figure 7 The heights at both ends of the super - large - span steel box in the length direction are different. During the concrete construction, a two - stage perfusion process is adopted. The spatial pouring sequence is layered and block - by - block pouring, and the pouring direction is from the low side to the high side. Specifically, it is carried out in the order of ① - ⑨ in Figure 7 for pouring.

[0062] Stage 1: The rapid perfusion and filling stage, pouring unit ① and unit ②.

[0063] In this stage, the amount of concrete poured inside the steel box is small, and the evolution of air bubbles is not much. The soil flow rate is fast and the filling performance is excellent, so most of the internal volume of the steel box can be quickly filled in a relatively short time.

[0064] In the first stage, the pouring is carried out in two layers, and the height of each layer of pouring is half of the water head height at the low end of the capping beam, about 1 - 1.2 m.

[0065] The specific operation process is as follows: Along the length direction of the steel box, a number of perfusion holes 1 are arranged at intervals on the top surface of the steel box. The distance between adjacent perfusion holes 1 is 3 - 4 m, and the diameter of the perfusion hole 1 is 10 - 20 cm. The concrete mixture is transported to the pouring site by a tank truck, the concrete is discharged into the hopper, and the hopper is lifted to the pouring hole by a crane for discharging. The discharging is carried out from one end of the box body to the other end. The discharging is carried out in sequence from the perfusion hole 1 at one end of the box body to the perfusion hole 1 at the other end, and two rounds of perfusion are carried out. In the first round, each perfusion hole 1 is perfused to the middle position. When the last perfusion hole 1 is perfused, the height of the concrete in the box chamber is about 1 - 1.2 m. In the second round, the hopper returns to the initial perfusion hole 1 for pouring. When it is full, the perfusion hole 1 is immediately blocked, and then it is moved to the next perfusion hole 1 until all the perfusion holes 1 are blocked.

[0066] Preferably, the corresponding perfusion holes can be flexibly selected according to the concrete flow situation for perfusion to make the surface of the concrete in the box self-leveling. When the concrete starts to overflow from the low-side slurry overflow pipe, it indicates that the concrete water head height basically reaches the top surface of the low side of the capping beam, marking the end of the perfusion process in the first stage and entering the second stage.

[0067] Stage Two: The stage of pouring and compacting each block at the top, pouring units ③ - ⑨.

[0068] In this stage, the range between each perfusion hole is divided into independent pouring units, and each unit is poured and compacted one by one in the pouring order from the low end to the high end. For example, when pouring unit ⑥, continuously pour concrete into perfusion hole E. During the perfusion process, use a low-frequency vibrating vibrator to assist in vibrating to make the concrete around the perfusion hole flow and compact in the narrow space at the top. As Figure 7 shown, when fresh concrete continuously emerges from perfusion hole D and the air vent between perfusion holes D and E for 3 - 5 minutes, it is considered that unit ⑥ is basically poured and compacted, and perfusion hole D is blocked to prevent continuous pollution of the capping top surface by the continuous overflow from perfusion hole D. After that, pour and compact each unit from the low end to the high end one by one.

[0069] In the second stage, it is most difficult to compact the concrete in the highest area of the bent cap because the space inside the box is narrow at this time, the bubble discharge speed is insufficient, and it is very difficult to compact the top cavity, which is also the pouring area that takes the longest time. Therefore, in this pouring process, the number of exhaust holes is increased in the high side area of the bent cap to assist the rapid discharge of bubbles and improve the pouring density. The technical key points of the pouring process in the final stage are as follows: (1) When pouring into the last unit ⑩, continuously pour concrete into the pouring hole I, and use a low-frequency vibrator around the pouring hole to assist the flow and compaction of the concrete in the middle area between the two pouring holes. When fresh concrete continuously emerges from the pouring hole H for 3 - 5 minutes, block the pouring hole H and continue to pour concrete from the pouring hole I.

[0070] (2) After slurry oozes out from the pouring hole I, observe whether the slurry overflow pipe oozes out slurry. If slurry oozes out, stop pouring after fresh concrete continuously emerges for 3 - 5 minutes and consider that the inside of the bent cap box is basically filled; if the slurry overflow pipe never oozes out slurry, connect the pump pipe to the slurry overflow pipe and inject slurry into the slurry overflow pipe, and observe whether the pouring hole I continuously oozes out slurry. If the pouring hole I continuously oozes out slurry for 3 - 5 minutes, stop pouring and consider that the inside of the bent cap box is basically filled. If the pouring hole I does not ooze out slurry, immediately stop pouring and do not continue pumping. Use local injection of grouting materials to assist in compaction. When pumping into the slurry overflow pipe, since the inside of the box is in a relatively filled state, the pumping pressure control should be as small as possible, just slightly larger than the hopper pouring pressure.

[0071] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A concrete construction method for a steel-concrete composite cap beam, characterized in that: On the top surface of the steel box, a number of pouring holes are arranged at intervals along its length; When the height difference between the two ends of the steel box is less than 10cm, the construction includes: Mixing self-compacting concrete; The pouring is carried out in two times, each time using a pressureless hopper, starting from the pouring hole at one end of the steel box to the pouring hole at the other end; When the height difference between the two ends of the steel box is ≥10cm, the construction includes: Mixing self-compacting concrete; Stage 1 pouring: pouring is carried out in two times, each time using a pressureless hopper, starting from the pouring hole at one end of the steel box to the pouring hole at the other end, until the concrete liquid level reaches the lower end level; Phase II pouring: Divide the area between the pouring holes into independent pouring units and pour them one by one in the order from the short end to the high end; Among them, the mass proportion of the slurry in the self-compacting concrete is ≥50%, the maximum aggregate particle size is ≤20mm, the aggregate with a particle size of 10-20mm does not exceed 30% of the total volume, the slump is 250-280mm, and the expansion is 600-650mm.

2. The concrete construction method of the steel-concrete composite cap beam according to claim 1, characterized in that: The self-compacting concrete is prepared by including the following raw materials in parts by weight: 340-400 parts of cement, 750-800 parts of sand, 500-550 parts of 5-10mm small gravel, 400-450 parts of 10-20mm gravel, 30-60 parts of fly ash, 160-165 parts of water, 6-8 parts of water reducer, and 40-45 parts of expansion agent.

3. The concrete construction method of the steel-concrete composite cap beam according to claim 2, characterized in that: Self-compacting concrete also includes 1-2 parts of water retaining agent, 1-2 parts of air entraining agent, and 2-3 parts of defoaming agent.

4. The concrete construction method of the steel-concrete composite cap beam according to claim 1, characterized in that: The distance between adjacent injection holes is ≤4m.

5. The concrete construction method of the steel-concrete composite cap beam according to claim 4, characterized in that: The distance between adjacent injection holes is 3-4m.

6. The concrete construction method of the steel-concrete composite cap beam according to claim 4, characterized in that: Vent holes are arranged between adjacent injection holes.

7. The concrete construction method of the steel-concrete composite cap beam according to claim 1, characterized in that: The diameter of the perfusion hole is 10 to 20 cm.

8. The concrete construction method of the steel-concrete composite cap beam according to claim 1, characterized in that: The pressureless hopper is a V-shaped funnel; the time for the self-compacting concrete to pass through the pressureless hopper is 10-20 seconds.

9. The concrete construction method of the steel-concrete composite cap beam according to any one of claims 1 to 8, characterized in that: During pouring, the self-compacting concrete is discharged into the hopper, and a crane is used to lift the hopper to the pouring hole for discharge.

10. The concrete construction method of the steel-concrete composite cap beam according to claim 9, characterized in that: When the perfusion is performed twice, For the first pouring, each pouring hole is poured to the middle position. When the last pouring hole is poured, the height of the concrete in the box is 20-30cm away from the height of the pouring hole. For the second pouring, the hopper returns to the initial pouring hole for pouring. When it is full, the pouring hole is immediately sealed and then moved to the next pouring hole until all the pouring holes are sealed.

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