CN115787486A - Construction method for prefabricating UHPC formwork core filling concrete pier - Google Patents

Abstract

A prefabricated UHPC (ultra high performance concrete) shuttering core-filling concrete pier is built on a bearing platform, a concrete pouring cavity is arranged in a shuttering, and a steel bar framework is arranged in the pouring cavity. The UHPC formwork is formed by connecting a plurality of prefabricated UHPC formwork sections, the upper end surface of the formwork section below the joint and the lower end surface of the formwork section above the joint are both provided with fibers which extend out, and the prefabricated UHPC formwork sections and the upper end surface of the upper formwork section are connected into a whole through ultra-high performance concrete slurry. During construction, a UHPC formwork section with fibers extending out of the end face is prefabricated firstly, a steel bar embedded in a bearing platform is lengthened to form a first section of a steel bar framework of the pier, one formwork section is sleeved on the steel bar framework, core filling concrete is poured, the steel bar is lengthened to form a new section of the steel bar framework, a new formwork section is installed, the joint of the two formwork sections is connected through ultra-high performance concrete slurry, and the core filling concrete is poured. The operation is thus circulated to form a pier. The formwork sections are convenient to transport, the vertical formwork does not need to be dismantled on site, the production efficiency is high, the formwork cost is saved, and the construction safety is improved.

Description

Construction method for prefabricating UHPC (ultra high performance concrete) formwork core-filling concrete pier

Technical Field

The invention relates to the technical field of building construction, in particular to a construction method for a prefabricated UHPC (ultra high Performance concrete) formwork core-filling concrete pier.

Background

With the continuous development of economy in China, the scale of basic construction such as bridges is continuously enlarged, higher requirements are put forward on the aspects of production quality, production efficiency, energy conservation, environmental protection and the like of bridge construction, and pier columns of bridge substructure structures are indispensable components in bridge construction.

The traditional cast-in-place pier stud is used for erecting a template, binding a reinforcement cage and pouring concrete on a construction site, and has the advantages of strong seismic resistance of a connecting node and good structural integrity, but has the following defects:

(1) The vertical template is required to be disassembled on site, the template requirement is large, the time consumption for the template disassembly is long, the turnover efficiency is low, and the construction period is long;

(2) The poured pier body concrete is common concrete, the tensile property, the durability and the like are relatively weak, the diseases such as pier body cracks, corrosion and the like can be generated when the design age is often not reached, and the later maintenance cost is high;

(3) All procedures of the cast-in-place pier column are operated on site, the component quality is restricted by factors such as the technical level of workers, weather conditions, the surrounding environment and the like, the standardized production cannot be realized, the production efficiency is low, the site pollution is large, and the method is not energy-saving and environment-friendly.

The whole prefabricated pier stud of tradition is for prefabricating whole pier stud in the mill, transports to hoist to the job site, pours connected node and forms bridge structures wholly, and its advantage is that industrialized production installation can be realized, nevertheless has following shortcoming:

(1) The fully-prefabricated pier stud, the capping beam, the bearing platform and other components are not integrally cast, and the connecting node is cast in situ, so that the connecting quality is difficult to ensure, the structural integrity is relatively poor, and the fully-prefabricated pier stud is not suitable for being used in a high-intensity area;

(2) The integral pier stud is prefabricated in a factory and then transported to the site, the weight of the pier stud is large, the transportation cost is high, and the site hoisting difficulty is large;

(3) The size and the length of the integrally prefabricated pier stud are fixed, the design is often customized, the assembly flexibility is poor, and the universality is low.

Disclosure of Invention

In order to solve the problems of rapid production of bridge pier columns, template saving, reduction of transportation cost and hoisting difficulty and improvement of production efficiency on the premise of ensuring good structural integrity, high safety, strong shock resistance and good durability of bridges in the background technology, the invention provides a construction method for prefabricating a UHPC (ultra high performance concrete) formwork core-filling concrete pier.

The technical problem to be solved by the invention is realized by adopting the following technical scheme: the surface layer of the concrete member is a prefabricated UHPC formwork, the UHPC formwork is formed by splicing UHPC formwork units, fibers extend from two opposite end surfaces of a joint, and after slurry poured into the joint is solidified, two adjacent UHPC formwork units are spliced.

The pier adopts the structure as above, and the UHPC formwork unit is a prefabricated UHPC formwork section; concrete is poured in a pouring cavity in the UHPC formwork, and a steel bar framework is arranged in the pouring cavity; the construction comprises the following steps:

s1: designing and manufacturing a UHPC formwork section with an end face provided with a protruding fiber according to the actual bridge attribute, and transporting the prefabricated UHPC formwork section to a construction site;

s2: lengthening the steel bars embedded in the bearing platform to form a first section steel bar framework of the pier:

s3: sleeving the first formwork section on the first section of the steel bar framework, positioning and fixing, and pouring the first section of core filling concrete;

s4: lengthening the steel bar framework to form a new section of steel bar framework:

s5: installing a new section of formwork section, pouring slurry into the joint of the two UHPC formwork sections, and connecting the two UHPC formwork sections after the slurry is solidified: s6: pouring new core filling concrete;

s7: if the pier does not reach the designed height, the cycle operation is started from step S4.

Preferably, the fibres are steel fibres and more than half of the protruding fibres have a protruding length of 30% to 70% of the length of an individual fibre.

Preferably, the slurry has the same formulation as UHPC, referred to as UHPC slurry, except that it does not contain steel fibres; or the slurry is epoxy structural adhesive.

Preferably, the distance from the upper surface of the core-filling concrete poured each time to the upper end surface of the UHPC formwork section at that time is 200 mm-1000 mm except the pier top concrete poured at the last time.

Preferably, a UHPC formwork is arranged inside the pier, and the pier is a hollow component.

Preferably, at least three supporting projections with the designed width of the seam are arranged on the bottom end surface of the UHPC mould shell section above the seam, and the top end surface of the UHPC mould shell section below the seam is provided with the same number of supporting areas distributed at corresponding positions; no fiber extends out of the supporting area; when UHPC form sections are connected, the upper support projections are supported on the lower support zones.

Preferably, the extended fibers of both end faces of the UHPC formwork section are arranged in rows, the direction of each row being along the normal of the UHPC formwork surface at the position; the fiber rows of the extending fibers on the top end surface of the UHPC formwork section below the seam and the fiber rows of the extending fibers on the bottom end surface of the UHPC formwork section above the seam are alternately inserted between the corresponding fiber rows of the other.

Preferably, said protruding fibers are flat; in the preparation stage of manufacturing the UHPC mould shell section, a plurality of fibers are glued together to manufacture a strip nail form, and the fibers are inserted into fiber positioning grooves of a base and a top cover of the UHPC mould shell section by adopting a nail gun; the fiber positioning grooves are filled with meltable polymers, and the polymers are softened by heating during the process of inserting fibers and removing the templates; after the polymer is cured, the surface of the polymer in the fiber positioning groove is flush with the groove edge of the fiber positioning groove.

Preferably, the fiber positioning slot in the base or the top cover is modular and is formed by splicing a plurality of detachable slot segments.

The invention has the beneficial effects that:

(1) The fiber-doped Ultra-High Performance Concrete (UHPC for short) is adopted to manufacture the disassembly-free template, and the Ultra-compactness of the UHPC can improve the impermeability of the pier, thereby improving the structural durability and prolonging the service life of the pier; the tensile strength and the high toughness of the UHPC exceeding 10MPa can improve the crack resistance and the seismic energy consumption capacity of the pier;

(2) The technical scheme of the invention can avoid or reduce the high-altitude operation amount in the construction process of the bridge pier and improve the construction safety;

(3) The standardized and modularized rapid production of the permanent bridge template can be realized, the template is saved, and the transportation cost and the hoisting difficulty are reduced;

(4) According to the invention, the adjacent UHPC formwork sections are connected at the joint, so that the welding operation at the conventional joint can be avoided, the workload at the contact part is small, the appearance of pier bodies is uniform, and the joint has enough connection strength, so that the whole formwork is integrated;

(5) At least three supporting convex blocks with the height being the designed width of the joint are arranged on the bottom end face of the UHPC formwork section above the joint of the adjacent UHPC formwork sections, and the top end face of the UHPC formwork section below the joint is provided with the same number of supporting areas distributed at corresponding positions, so that the positioning and the supporting of a new formwork section in construction are facilitated, and the construction is convenient;

(6) The straight fibers are adopted and are made into a strip nail form in advance, the fibers are inserted by the nail gun, the working efficiency of fiber insertion can be improved, and the fibers are inserted quickly and accurately under the coordination of other auxiliary positioning tools;

(7) Fusible polymer is filled in the fiber positioning groove, and is in a solid state in the manufacturing process of the UHPC mold shell section; during the preparation stage and the dismantling period of the UHPC mould shell section, the fiber positioning groove can be heated to soften the meltable polymer, so that the fiber can be conveniently inserted and pulled out, and the operation purpose that the fiber extends out of the end face of the UHPC mould shell section is conveniently realized.

Drawings

FIG. 1 is a schematic view of a circular prefabricated UHPC form section of example 1;

FIG. 2 is an enlarged partial view of A of FIG. 1;

FIG. 3 is a schematic view of the connection of two adjacent prefabricated UHPC shell segments above and below;

FIG. 4 is an enlarged partial view of B in FIG. 3;

FIG. 5 is a schematic top end view of the lower prefabricated UHPC mold shell section of FIG. 4;

FIG. 6 is a schematic cross-sectional view of a base ring for making a mold shell segment;

FIG. 7 is a schematic cross-sectional view of a template for making a mold shell segment;

FIG. 8 is a schematic view of a bearing platform and a first section of a steel reinforcement cage;

FIG. 9 is a schematic view of the structure after installation of the first prefabricated formwork section;

FIG. 10 is a schematic cross-sectional view of the initial shell section after core filling;

fig. 11 is a schematic structural view of the second section of the steel reinforcement cage after connection;

FIG. 12 is a schematic view of the second prefabricated form section after installation;

FIG. 13 is a schematic view of a seam treatment tool for a formwork section;

FIG. 14 is a schematic view of the structure of the first two shell sections after joining;

figure 15 is a schematic cross-sectional hoop view of the seam of figure 13;

figure 16 is a partial top schematic view of the base ring.

In the figure: 1-a first formwork section, 2-a supporting lug, 3-a supporting area, 4-chloroprene rubber, 5-a fiber positioning groove, 6-steel fiber, 7-an upper formwork section, 8-a lower formwork section, 9-a seam, 10-an air passage, 11-an outer formwork supporting area, 12-an inner formwork supporting area, 13-a base ring, 14-a top cover ring, 15-an outer formwork, 16-an inner formwork, 17-a bearing platform, 18-a first section of steel reinforcement framework, 19-core filling concrete, 20-a second section of steel reinforcement framework, 21-a second formwork section, 22-a hoop, 23-a suspension rope, 24-a rubber air bag, 25-an air pipe, 26-a steel plate strip, 27-a grout inlet hole and 28-a marking line.

Detailed Description

Example 1

The pier of this embodiment is double column type concrete pier, and the pier column is circular and uniform cross-section, and the external diameter 1800mm is high 20m. The construction adopts a prefabricated UHPC formwork as a permanent formwork, the core filling concrete is C40 conventional concrete, and a single UHPC formwork section is shown in figure 1 and figure 2. The outer diameter of the prefabricated UHPC mould shell section is 1800mm, the wall thickness is 40mm, and the height of the UHPC mould shell section is 2990mm. The seam width of two adjacent formwork sections is designed to be 10mm. Except the lowest mould shell section and the highest mould shell section, the end surfaces of two ends of each mould shell section are provided with steel fibers 6 which extend out, and the bottom end surface of each mould shell section is provided with three supporting convex blocks 2 with the height of 10mm, wherein the three supporting convex blocks are uniformly distributed along the circumference; correspondingly, on the top end face of the mould shell segment there are three bearing areas 3, three of which are also evenly distributed circumferentially. The supporting protrusions 2 have a thickness of 25mm and an inner surface on the inner surface of the formwork section, and are designed so that the supporting protrusions 2 are not visible from the outside after construction is completed, see fig. 5. The steel fibers 6 on the end faces of the die shell sections are arranged in rows, and the direction of each row passes through the center of a cross section of the pier. The fiber rows on the top and bottom of the shell sections are not perpendicular, and the fiber rows extending from the bottom of the top shell section 7 at the seam 9 between the top and bottom shell sections can be located in the gap between the fiber rows extending from the top of the bottom shell section 8, as shown in fig. 3 and 4. The steel fiber 6 is a straight fiber with a length of 18mm and a diameter of 0.4mm, the length of the exposed part is designed to be 8mm, and the length is 7mm to 9mm after considering the manufacturing error and is less than the width of the joint 9 by 10mm.

The specific construction process comprises the following steps:

s1: and manufacturing a prefabricated UHPC mold shell section with a protruding fiber at the end face of the prefabricated field according to the designed length of each mold shell section, and transporting the prefabricated UHPC mold shell section to a construction site. When the number of the formwork sections is too large, the formwork sections can be manufactured by a centrifugal method, and in the embodiment, a method of casting a vertical formwork in situ is adopted, as shown in fig. 6 and 7. The template comprises a base ring 13, a top cover ring 14, an outer mold 15 and an inner mold 16, wherein the outer mold 15 and the inner mold 16 are formed by assembling three blocks, and the side surfaces of the outer mold 15 and the inner mold 16, which are respectively provided with vertical seams, are inclined planes, so that the template is convenient to disassemble; the outer side of the outer mould 15 has a locking band in the height direction and likewise the inner side of the inner mould 16 has a circular support ring. The bottom end faces of the outer and inner dies 15, 16 are supported on the outer and inner die support areas 11, 12, respectively, of the base ring 13. Referring to the cross-sectional view of the base ring 13 shown in fig. 6, the fiber positioning groove 5 is formed between the outer mold supporting region 11 and the inner mold supporting region 12, the depth of the fiber positioning groove 5 is 12mm, and three annular air passages 10 are formed below the fiber positioning groove 5. The meltable polymer is selected from polyvinyl chloride, and its melting point is 50-80 deg.C; polychloroprene and chloroprene rubber can also be selected, and the melting points of the polychloroprene and the chloroprene rubber are both 43 ℃; the polycyclochloroethane may be selected to have a melting point of 66.2 ℃. The selection principle is mainly that the melting point is appropriate, the melting point is as low as possible under the condition that the temperature is higher than the daily temperature of a prefabricating field, and heating softening is convenient, and chloroprene rubber 4 is selected in the embodiment. In the preparation stage of manufacturing the UHPC mould shell section, a plurality of steel fibers 6 are glued together to be manufactured into a chain riveting mode, the steel fibers 6 are driven into fiber positioning grooves 5 of a base ring 13 and a top cover ring 14 by a nail gun, and steam is introduced into an air passage 10 in the process to soften chloroprene rubber 4; after the strength of the UHPC mould shell section meets the requirement, steam is introduced into the air passage 10 to soften the chloroprene rubber 4, and the mould is removed. In order to facilitate efficient insertion of the steel fibers 6, a marking line 28, see fig. 16, is formed in advance on the upper surface of the base ring 13 and the lower surface of the top cover ring 14, the inner end of the marking line 28 points to the center of the circle, the upper surface of the base ring 13 is marked with the positions of the supporting protrusions 2 at the same time, and the lower surface of the top cover ring 14 is marked with the positions of the supporting areas 3 at the same time. The supporting protrusions 2, which are prefabricated in advance, are placed in the designated positions in the fiber positioning grooves 5 and bonded with a little glue. After the polymer has solidified, the surface of the polymer of the fiber positioning slot 5 is flush with the outer mold support zone 11 and the inner mold support zone 12. In order to facilitate the separation of the polymer from the steel fibers 6 during the form removal, the surface of the fiber positioning groove 5 is covered with a thin polyethylene film before the steel fibers 6 are inserted and beaten. After the UHPC formwork section is demoulded, two end faces can be washed by high-pressure water to make the end faces rough.

S2: and (3) lengthening the steel bars pre-embedded in the bearing platform 17 to form a first section of steel reinforcement framework 18 of the pier, as shown in figure 8. The steel reinforcement framework comprises a vertical main reinforcement and a circumferential stirrup, and the stirrup is arranged on the outer side of the main reinforcement. A pit for installing the formwork section is reserved in the bearing platform 17.

S3: sleeving the first formwork section 1 on the first steel reinforcement framework 18, positioning and fixing, and referring to fig. 9; core concrete 19 is poured, see fig. 10.

S4: the reinforcement is lengthened to form a new length of the rebar skeleton, see fig. 11 (the new rebar skeleton in fig. 11 is a second length of the rebar skeleton 20).

S5: a new section of formwork section is installed and adjusted so that the bearing lugs 2 on its lower end face correspond to the bearing areas 3 of the lower formwork section, see fig. 12 (the new formwork section in fig. 12 is the second formwork section 21). Ultra-high concrete slurry without fibers (UHPC slurry for short) is poured into the joint 9 of two prefabricated UHPC mould shell sections, the two UHPC mould shell sections are connected after the UHPC slurry is solidified, and the effect schematic diagram of the joint 9 is shown in figure 14 after the joint operation is completed. Fig. 13 is a schematic view of a seam 9 treatment tool for formwork sections, the tool being shown in cross-section in fig. 15. Lowering a hoop 22 outside the formwork section by using a suspension rope 23; the hoop 22 is made of hard plastic, one side of the hoop is open, a rubber air bag 24 which surrounds the seam 9 for a circle is arranged in the hoop, and the air pipe 25 is connected with the rubber air bag 24. The rubber bladder 24 side facing the formwork is previously coated with industrial vaseline. Inside the formwork, a circle of steel strips 26 is adhered to the formwork section below the seam 9, and slurry inlet holes 27 are arranged on the steel strips 26. After the hoop 22 is lowered into position, the air is vented into the bladder 24 so that it is held tightly against the seam 9 for one revolution. UHPC grout is pressed into the joint through the grout inlet hole 27 until the UHPC grout rises to be close to the upper edge of the steel plate strip 26, and the filling in the joint 9 is ensured to be full.

S6: pouring new core concrete 19;

s7: if the pier does not reach the design height, the process is cycled from step S4.

And finally, finishing the construction work of the pier.

Example 2

This example is a modification of example 1, where the entire UHPC formwork is first spliced on site on the ground, and then the core-filling concrete is poured. The construction comprises the following steps:

s1: designing and manufacturing a UHPC formwork section with an end face provided with a stretched fiber according to the actual bridge attribute, and transporting the prefabricated UHPC formwork section to a construction site;

s2: the reinforcing steel bars pre-buried in the cushion cap 17 are lengthened to form a steel bar framework of the pier: in order to enhance the stability of the steel bar framework, a plurality of inclined supports can be arranged;

s3: sequentially ending and connecting all UHPC formwork sections of the pier, horizontally placing the UHPC formwork sections on a set support, wherein each UHPC formwork section has at least two support points;

s4: grouting slurry into the joint of two adjacent UHPC formwork sections, and connecting the UHPC formwork sections into an integral UHPC formwork after the slurry is solidified:

s5: hoisting the UHPC formwork, sleeving the UHPC formwork outside the steel bar framework, adjusting the position and the verticality of the UHPC formwork, and pouring connecting concrete between the UHPC formwork and the bearing platform 17:

s6: pouring core filling concrete;

s7: and constructing a pier top section.

It should be noted that the term "above" in the present invention does not have a vertical meaning in mathematics, and has an engineering meaning, and shall include "directly above" and "obliquely above"; similarly, "below" shall include "directly below" and "obliquely below". The pier in the invention is not a vertical pier which is straight up and straight down, and can be in an inclined shape, or the bottom of the pier can be a vertical section, and the upper part of the pier is provided with an inclined branch; in addition, the term "pier" herein also includes a portion extending vertically or branched to the bridge deck, such as a pylon in a cable-stayed bridge and a pylon in a suspension bridge, and also falls within the scope of the present invention.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make many possible variations and modifications to the disclosed solution, or modify equivalent embodiments using the teachings disclosed above, without departing from the scope of the solution. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence should fall within the protection scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.

Claims (10)

1. A prefabricated UHPC formwork concrete component is characterized in that: the surface layer of the concrete member is a prefabricated UHPC formwork, the UHPC formwork is formed by splicing UHPC formwork units, fibers extend out from two opposite end faces of a joint, and after slurry poured into the joint is solidified, two adjacent UHPC formwork units are spliced.

2. A construction method of a prefabricated UHPC formwork core-filled concrete pier, which adopts the structure of claim 1, characterized in that: the UHPC mould shell unit is a prefabricated UHPC mould shell section; concrete is poured in a pouring cavity in the UHPC formwork, and a steel bar framework is arranged in the pouring cavity; the construction comprises the following steps:

s1: designing and manufacturing a UHPC formwork section with an end face provided with a protruding fiber according to the actual bridge attribute, and transporting the prefabricated UHPC formwork section to a construction site;

s2: lengthening the steel bars embedded in the bearing platform to form a first section steel bar framework of the pier:

s3: sleeving a corresponding UHPC formwork section on a first section of steel bar framework, positioning and fixing, and pouring first section core filling concrete;

s4: lengthening the steel bar framework to form a new section of steel bar framework:

s5: installing a new section of UHPC mould shell section, pouring slurry into the joint of the two UHPC mould shell sections, and connecting the two UHPC mould shell sections after the slurry is solidified:

s6: pouring new core filling concrete;

s7: if the pier does not reach the designed height, the cycle operation is started from step S4.

3. The construction method of the prefabricated UHPC formwork core-filled concrete pier as claimed in claim 2, wherein: the fibers are steel fibers, and the protruding length of more than half of the protruding fibers is 30% to 70% of the length of a single fiber.

4. The construction method of the prefabricated UHPC formwork core-filled concrete pier as claimed in claim 2, wherein: the slurry was the same formulation as UHPC except that it contained no fiber; or the slurry is epoxy structural adhesive.

5. The construction method of the prefabricated UHPC formwork core-filled concrete pier as claimed in claim 2, wherein: apart from the pier top concrete poured at the last time, the distance from the upper surface of the core filling concrete poured at each time to the upper end surface of the UHPC formwork section at that time is 200-1000 mm.

6. The construction method of the prefabricated UHPC formwork core-filled concrete pier as claimed in claim 2, wherein: a UHPC formwork is arranged in the pier, and the pier is a hollow member.

7. The construction method of the prefabricated UHPC formwork core-filled concrete pier as claimed in claim 2, wherein: at least three supporting convex blocks with the height of the designed width of the joint are arranged on the bottom end surface of the UHPC mould shell section above the joint, and the top end surface of the UHPC mould shell section below the joint is provided with the same number of supporting areas which are distributed at corresponding positions; no fiber extends out of the supporting area; when the UHPC form sections are connected, the upper bearing projections bear against the lower bearing zones.

8. The construction method of the prefabricated UHPC formwork core-filled concrete pier as claimed in claim 2, wherein: the extended fibers of the two end faces of the UHPC formwork section are arranged in rows, and the direction of each row is along the normal of the surface of the UHPC formwork at the position; the fiber rows of the extending fibers on the top end face of the UHPC formwork section below the seam and the fiber rows of the extending fibers on the bottom end face of the UHPC formwork section above the seam are alternately inserted between the corresponding fiber rows of the other.

9. The construction method of the prefabricated UHPC formwork core-filled concrete pier according to claim 8, characterized in that: the protruding fibers are straight; in the preparation stage of manufacturing the UHPC mould shell section, a plurality of fibers are glued together to manufacture a standard strip nail form, and the fibers are inserted into fiber positioning grooves of a base and a top cover in a mould plate of the UHPC mould shell section by adopting a nail gun; the fiber positioning grooves are internally provided with hot-melt polymers, and the polymers are heated to be softened before the fibers are inserted and the templates are removed; after the polymer is cured, the surface of the polymer in the fiber positioning groove is flush with the groove edge of the fiber positioning groove.

10. The construction method of the prefabricated UHPC formwork core-filled concrete pier according to claim 9, wherein: the fiber positioning grooves in the base or the top cover are modularized and are formed by splicing a plurality of detachable groove sections.

Images