CN115652791A - Cast-in-place box girder construction method - Google Patents
Cast-in-place box girder construction method Download PDFInfo
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- CN115652791A CN115652791A CN202211333070.XA CN202211333070A CN115652791A CN 115652791 A CN115652791 A CN 115652791A CN 202211333070 A CN202211333070 A CN 202211333070A CN 115652791 A CN115652791 A CN 115652791A
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Abstract
The invention provides a cast-in-place box girder construction method, which comprises the following steps: foundation treatment, namely backfilling and rolling a foundation pit of a bearing platform in a layered manner; erecting a support, wherein the onshore cast-in-place beam support adopts a full-hall disc buckle type scaffold, and the full-hall disc buckle type scaffold is supported on the hardened foundation; installing a box girder template and steel bars, sequentially completing the installation of a bottom template, a side template, a flange plate template and a box chamber template, and completing the installation of the steel bars and the prestressed pipelines of a bottom plate, a web plate and a diaphragm girder; concrete is poured, the concrete is transported by a concrete tank truck, and a pump truck and a trailer pump are directly distributed, poured and vibrated uniformly; curing the concrete, and immediately covering a plastic film on the top surface after the beam concrete is poured; according to the cast-in-place beam construction method disclosed by the invention, the foundation is compacted to ensure that the compaction degree reaches more than 90%, the full-hall disc-buckled scaffold is adopted at the top of the foundation, the structure is simple, the splicing can be rapidly completed, the bearing capacity is large, the construction is safe and reliable, the control is easy, the danger is reduced, and the reliability is improved.
Description
Technical Field
The invention belongs to the technical field of box girder construction, and particularly relates to a cast-in-place box girder construction method.
Background
The box girder of the reinforced concrete structure is divided into a prefabricated box girder and a cast-in-place box girder, and the cast-in-place box girder is mainly used for a large continuous bridge.
In the prior art, chinese patent application with publication number CN112813791a discloses a support for a cast-in-place box girder and a construction method thereof, wherein the support for the cast-in-place box girder comprises a pile foundation, a cross beam, a support frame and a bailey frame, the bailey frame is supported on the support frame, a support point is located at a web member of the bailey frame, the support frame is arranged on the cross beam, the cross beam is arranged at the upper end of the pile foundation, and the lower end of the pile foundation extends into the ground. The construction method comprises the steps of building a support frame, constructing a pile foundation, installing a cross beam, hoisting the support frame, installing adjacent pile foundations and hoisting a bailey frame.
In the prior art, the Bailey frames are adopted to support the cast-in-place box beam, sand boxes and cross beam systems in the Bailey beam structure are unsafe and difficult to control, and the sand boxes are not horizontal and the cross beams are deformed, so that the Bailey beam frames are inclined and collapsed, and the Bailey beam frames are high in danger.
Therefore, a cast-in-place box girder construction method which is easy to control and reduces the danger needs to be designed to solve the technical problems faced at present.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the cast-in-place box girder construction method which is easy to control and reduces the danger.
The technical scheme of the invention is as follows: the cast-in-place box girder construction method comprises the following steps:
foundation treatment, namely backfilling and rolling a foundation pit of a bearing platform layer by layer to ensure that the compactness of the foundation pit reaches over 90 percent, and hardening the foundation;
the method comprises the following steps of erecting a support, wherein a land cast-in-place beam support adopts full-hall disc buckling type scaffolds which are supported on a hardened foundation, the full-hall disc buckling type scaffolds are arranged along the bridge direction at intervals of 900mm, the cross sections are adjusted according to beam widths, width and pier body forms, and the full-hall disc buckling type scaffolds are pre-pressed according to 120% of load after being finished;
installing a box girder template and steel bars, sequentially completing the installation of a bottom template, a side template, a flange plate template and a box chamber template, and finishing the installation of the steel bars and the prestressed pipelines of a bottom plate, a web plate and a diaphragm girder;
pouring concrete, wherein the concrete is intensively mixed by a mixing station and transported by a concrete tank truck, and a pump truck and a trailer pump directly distribute, pour and vibrate uniformly;
concrete curing, namely immediately covering a plastic film on the top surface after beam concrete pouring is finished, and keeping the surface humidity of the concrete; covering the earthwork cloth after the form is removed, watering to keep the surface of the concrete moist, and maintaining for more than 14 days.
And in the step of foundation treatment, backfilling the interior of the foundation pit of the bearing platform to be flush with the top of the bearing platform through broken stones and yellow sands, and then paving a cement soil layer, a plant-mixed regenerated water-stabilized gravel layer, an anti-crack embedded extrusion type water-stabilized gravel layer and an asphalt concrete layer on the top of the foundation pit in sequence.
The asphalt concrete layer is provided with a Su-25 asphalt concrete layer, a Su-20 asphalt concrete layer and an SMA-13 asphalt mixture layer which are sequentially paved on the top of the anti-crack embedded and extruded type water-stable gravel layer.
The bottom of cement soil layer has been laid and has been moulded the grid, laid polyester cloth between cement soil layer and the plant-mixed regeneration water steady gravel layer, asphalt concrete layer with it inlays crowded type water steady gravel layer to resist has laid polyester cloth between the crack.
The cement soil layer is formed by paving 3.5% of cement soil or lime soil recycled materials.
In the step of installing the box girder template and the reinforcing steel bars, the width of the bottom template is not less than that of the bottom of the box girder, and two sides of the bottom template exceed the turning direction of the bottom girder respectively by at least 5cm.
In the concrete pouring step, direct blanking and layered pouring are adopted during web concrete pouring, webs on two sides are symmetrically and uniformly blanked during blanking so as to avoid uneven load on the template, the layered thickness of the concrete is 30cm, and an inserted vibrator vibrates; when the bottom plate concrete is poured, reserving concrete feed openings at the top of the inner mold along the longitudinal bridge direction at intervals of 4m, after the bottom plate is poured, timely filling the template at the feed openings, and reinforcing and bracing; and (5) compacting and leveling the concrete on the top surface of the box girder.
When the plug-in vibrator vibrates, the vibrating rod of the plug-in vibrator needs to enter and exit the lower layer concrete for 5-10 cm, the moving distance of the vibrating rod is preferably 25-35 cm, and each vibration lasts for 10-15 s.
The bottom template, the side templates and the flange plate templates are all bamboo plywood.
The invention has the beneficial effects that:
(1) According to the cast-in-place beam construction method disclosed by the invention, the foundation is compacted to ensure that the compaction degree of the foundation reaches more than 90%, the full-hall disc buckle type scaffold is adopted at the top of the foundation, the structure is simple, the splicing can be rapidly completed, the bearing capacity is large, the safety and the reliability are high, the control is easy, the danger is reduced, and the reliability is improved;
(2) The cross section is adjusted according to the difference of beam width, framing and pier shaft form, can splice according to corresponding dimensions, uses the flexibility better, and its is small in addition, convenient transportation and stack.
Drawings
Fig. 1 is a flow chart of a method of a cast-in-place box girder construction method in the invention.
Detailed Description
Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the invention, its application, or uses. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It should be noted that: the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values set forth in these embodiments are to be construed as merely illustrative, and not as limitative, unless specifically stated otherwise.
The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element preceding the word covers the element listed after the word, and does not exclude the possibility that other elements are also covered. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
As shown in fig. 1, the cast-in-place box girder construction method includes the following steps:
foundation treatment, namely backfilling and rolling foundation pits of a bearing platform layer by layer to ensure that the compaction degree of the foundation pits reaches more than 90%, hardening the foundation, for example, hardening a C15 concrete cushion layer with the thickness of 15cm, wherein the foundation filling range has a mud pit used in the pile foundation construction process, before filling, mud in the mud pit must be removed, soil and stones are adopted for filling, and the foundation is tamped by layer;
the method comprises the following steps of erecting a support, wherein a land cast-in-place beam support adopts full-hall disc buckling type scaffolds which are supported on a hardened foundation, the full-hall disc buckling type scaffolds are arranged along the bridge direction at intervals of 900mm, the cross sections are adjusted according to beam widths, width and pier body forms, and the full-hall disc buckling type scaffolds are pre-pressed according to 120% of load after being finished;
installing a box girder template and steel bars, sequentially completing the installation of a bottom template, a side template, a flange plate template and a box chamber template, and completing the installation of the steel bars and the prestressed pipelines of a bottom plate, a web plate and a diaphragm girder;
pouring concrete, wherein the concrete is intensively mixed by a mixing station and transported by a concrete tank truck, and a pump truck and a trailer pump directly distribute, pour and vibrate uniformly;
curing the concrete, namely immediately covering a plastic film on the top surface after the beam concrete is poured, and keeping the surface humidity of the concrete; covering the geotextile after the form is removed, sprinkling water to keep the surface of the concrete moist, and maintaining for more than 14 days;
in the embodiment, the foundation is compacted to ensure that the compaction degree of the foundation reaches more than 90 percent, the full-hall disc buckle type scaffold is adopted at the top of the foundation, the structure is simple, the splicing can be rapidly completed, the bearing capacity is large, the safety and the reliability are high, the control is easy, the danger is reduced, and the reliability is improved; the cross section is adjusted according to the difference of beam width, framing and pier shaft form, can splice according to corresponding dimensions, uses the flexibility better, and its is small in addition, convenient transportation and stack.
In some embodiments, the foundation treatment step includes backfilling the inside of a foundation pit of a bearing platform to be level with the top of the bearing platform through broken stones and yellow sands, and then paving a cement soil layer, a plant-mixed reclaimed water stable gravel layer, an anti-crack embedded extrusion type water stable gravel layer and an asphalt concrete layer on the top of the foundation pit in sequence.
In some embodiments, the asphalt concrete layer has a Sup-25 asphalt concrete layer, a Sup-20 asphalt concrete layer and an SMA-13 asphalt mixture layer laid on top of the anti-crack embedded squeeze-resistant water-stable gravel layer in sequence.
In some embodiments, a steel-plastic grille is laid at the bottom of the cement soil layer, and the steel-plastic composite geogrid is wrapped by high-strength steel wires through high-density polyethylene into a high-strength strip, so that the interlocking and meshing effects of a reinforced bearing surface can be effectively improved, the bearing capacity of a foundation can be greatly enhanced, the lateral displacement of the soil body can be effectively restrained, and the stability of the foundation can be enhanced; polyester cloth is laid between the cement soil layer and the plant-mixed recycled water-stable gravel layer, polyester cloth is laid between the asphalt concrete layer and the anti-crack embedded extrusion type water-stable gravel layer, and the polyester cloth is breathable and water-permeable polymer fiber cloth.
In some embodiments, the soil cement layer is laid with 3.5% soil cement or lime soil regrind.
In some embodiments, in the step of installing the box girder formwork and the reinforcing steel bars, the width of the bottom formwork is not less than the width of the bottom of the box girder, and two sides of the bottom formwork exceed the bottom girder respectively and change direction by at least 5cm.
In the concrete pouring step in some embodiments, when the web plate concrete is poured, direct blanking and layered pouring are adopted, the web plates on two sides are symmetrically and uniformly blanked during blanking so as to avoid uneven load on the template, the layered thickness of the concrete is 30cm, and an insertion type vibrator is used for vibrating; when the bottom plate concrete is poured, reserving concrete feed openings at the top of the inner mold along the longitudinal bridge direction at intervals of 4m, after the bottom plate is poured, timely filling the template at the feed openings, and reinforcing and bracing; and (5) compacting and leveling the concrete on the top surface of the box girder.
In some embodiments, when the insert vibrator vibrates, the vibrating rod of the insert vibrator moves into and out of the concrete of the lower layer by 5-10 cm, the moving distance of the vibrating rod is preferably 25-35 cm, and each time of vibration is 10-15 s.
In the step of erecting the bracket in some embodiments, the full hall disc buckle type scaffold can be erected manually, and the steel pipe bracket construction is erected by adopting a truck crane or a crawler crane to be matched with a vibration hammer; during the prepressing process after the full hall disc buckle type scaffold is built, settlement and displacement observation points are arranged on midspan, 1/4 span and pier top sections, 4 measuring points are respectively arranged on corners and flanges of a bottom plate of each section, a crane lifts sandbags in place, the sandbags are loaded in a grading manner, and after ballast data observation is finished, the sandbags are unloaded step by step and the observation points are retested.
In some embodiments, the bottom form, the side forms, and the flange plate form are all bamboo plywood.
Thus, various embodiments of the present invention have been described in detail. Some details well known in the art have not been described in order to avoid obscuring the concepts of the present invention. Those skilled in the art can now fully appreciate how to implement the teachings disclosed herein, in view of the foregoing description.
The above-mentioned embodiments only express some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. A construction method of a cast-in-place box girder is characterized by comprising the following steps:
foundation treatment, namely backfilling and rolling a bearing platform foundation pit layer by layer to ensure that the compaction degree of the foundation pit reaches over 90 percent, and hardening the foundation;
the method comprises the following steps of erecting a support, wherein a land cast-in-place beam support adopts full-hall disc buckling type scaffolds which are supported on a hardened foundation, the full-hall disc buckling type scaffolds are arranged along the bridge direction at intervals of 900mm, the cross sections are adjusted according to beam widths, width and pier body forms, and the full-hall disc buckling type scaffolds are pre-pressed according to 120% of load after being finished;
installing a box girder template and steel bars, sequentially completing the installation of a bottom template, a side template, a flange plate template and a box chamber template, and completing the installation of the steel bars and the prestressed pipelines of a bottom plate, a web plate and a diaphragm girder;
pouring concrete, wherein the concrete is intensively mixed by a mixing station and transported by a concrete tank truck, and a pump truck and a trailer pump directly distribute, pour and vibrate uniformly;
curing the concrete, namely immediately covering a plastic film on the top surface after the beam concrete is poured, and keeping the surface humidity of the concrete; and covering the geotextile after the formwork is removed, spraying water to keep the surface of the concrete moist, and maintaining for more than 14 days.
2. The cast-in-place box girder construction method according to claim 1, characterized in that: and in the step of foundation treatment, backfilling the interior of the foundation pit of the bearing platform to be flush with the top of the bearing platform through broken stones and yellow sands, and then paving a cement soil layer, a plant-mixed regenerated water-stabilized gravel layer, an anti-crack embedded extrusion type water-stabilized gravel layer and an asphalt concrete layer on the top of the foundation pit in sequence.
3. The cast-in-place box girder construction method according to claim 2, characterized in that: the asphalt concrete layer is provided with a Su-25 asphalt concrete layer, a Su-20 asphalt concrete layer and an SMA-13 asphalt mixture layer which are sequentially paved on the top of the anti-crack embedded and extruded type water-stable gravel layer.
4. A cast-in-place box girder construction method according to claim 3, wherein: the bottom of cement soil layer has been laid and has been moulded the grid, laid polyester cloth between cement soil layer and the plant-mixed regeneration water steady gravel layer, asphalt concrete layer with it inlays crowded type water steady gravel layer to resist has laid polyester cloth between the crack.
5. The cast-in-place box girder construction method according to claim 2, characterized in that: the cement soil layer is formed by paving 3.5% of cement soil or lime soil recycled materials.
6. The cast-in-place box girder construction method according to claim 1, characterized in that: in the step of installing the box girder template and the reinforcing steel bars, the width of the bottom template is not less than that of the bottom of the box girder, and two sides of the bottom template exceed the turning direction of the bottom girder respectively by at least 5cm.
7. The cast-in-place box girder construction method according to claim 1, characterized in that: in the step of pouring the concrete, the concrete is poured,
when the web plate concrete is poured, direct blanking and layered pouring are adopted, the web plates on two sides are symmetrically and uniformly blanked during blanking so as to avoid uneven load on the template, the layered thickness of the concrete is 30cm, and the inserted vibrator vibrates;
when the bottom plate is poured with concrete, reserving concrete feed openings at the top of the inner mold along the longitudinal bridge direction at intervals of 4m, after the bottom plate is poured, timely filling the template at the feed openings, and reinforcing and bracing;
and (5) compacting and leveling the concrete on the top surface of the box girder.
8. The cast-in-place box girder construction method according to claim 7, wherein: when the plug-in vibrator vibrates, the vibrating rod of the plug-in vibrator needs to enter and exit the lower layer concrete for 5-10 cm, the moving distance of the vibrating rod is preferably 25-35 cm, and each vibration lasts for 10-15 s.
9. The cast-in-place box girder construction method according to claim 1, characterized in that: the bottom template, the side templates and the flange plate templates are all bamboo plywood.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211333070.XA CN115652791A (en) | 2022-10-28 | 2022-10-28 | Cast-in-place box girder construction method |
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| CN202211333070.XA CN115652791A (en) | 2022-10-28 | 2022-10-28 | Cast-in-place box girder construction method |
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